Functional diversity in gravitropic reaction among tropical seedlings in relation to ecological and developmental traits.

PubMed

Alméras, Tancrède; Derycke, Morgane; Jaouen, Gaëlle; Beauchêne, Jacques; Fournier, Mériem

2009-01-01

Gravitropism is necessary for plants to control the orientation of their axes while they grow in height. In woody plants, stem re-orientations are costly because they are achieved through diameter growth. The functional diversity of gravitropism was studied to check if the mechanisms involved and their efficiency may contribute to the differentiation of height growth strategies between forest tree species at the seedling stage. Seedlings of eight tropical species were grown tilted in a greenhouse, and their up-righting movement and diameter growth were measured over three months. Morphological, anatomical, and biomechanical traits were measured at the end of the survey. Curvature analysis was used to analyse the up-righting response along the stems. Variations in stem curvature depend on diameter growth, size effects, the increase in self-weight, and the efficiency of the gravitropic reaction. A biomechanical model was used to separate these contributions. Results showed that (i) gravitropic movements were based on a common mechanism associated to similar dynamic patterns, (ii) clear differences in efficiency (defined as the change in curvature achieved during an elementary diameter increment for a given stem diameter) existed between species, (iii) the equilibrium angle of the stem and the anatomical characters associated with the efficiency of the reaction also differed between species, and (iv) the differences in gravitropic reaction were related to the light requirements: heliophilic species, compared to more shade-tolerant species, had a larger efficiency and an equilibrium angle closer to vertical. This suggests that traits determining the gravitropic reaction are related to the strategy of light interception and may contribute to the differentiation of ecological strategies promoting the maintenance of biodiversity in tropical rainforests.

Effect of orifice length-diameter ratio on the coefficient of discharge of fuel-injection nozzles

NASA Technical Reports Server (NTRS)

Gelalles, A G; March, E T

1931-01-01

The variation of the coefficient of discharge with the length-diameter ratio of the orifice was determined for nozzles having single orifice 0.008 and 0.020 inch in diameter. Ratios from 0.5 to 10 were investigated at injection pressures from 500 to 5,000 pounds per square inch. The tests showed that, within the error of the observation, the coefficients were the same whether the nozzles were assembled at the end of a constant tube or in an automatic injection valve having a plain stem.

Measurements of stem diameter: implications for individual- and stand-level errors.

PubMed

Paul, Keryn I; Larmour, John S; Roxburgh, Stephen H; England, Jacqueline R; Davies, Micah J; Luck, Hamish D

2017-08-01

Stem diameter is one of the most common measurements made to assess the growth of woody vegetation, and the commercial and environmental benefits that it provides (e.g. wood or biomass products, carbon sequestration, landscape remediation). Yet inconsistency in its measurement is a continuing source of error in estimates of stand-scale measures such as basal area, biomass, and volume. Here we assessed errors in stem diameter measurement through repeated measurements of individual trees and shrubs of varying size and form (i.e. single- and multi-stemmed) across a range of contrasting stands, from complex mixed-species plantings to commercial single-species plantations. We compared a standard diameter tape with a Stepped Diameter Gauge (SDG) for time efficiency and measurement error. Measurement errors in diameter were slightly (but significantly) influenced by size and form of the tree or shrub, and stem height at which the measurement was made. Compared to standard tape measurement, the mean systematic error with SDG measurement was only -0.17 cm, but varied between -0.10 and -0.52 cm. Similarly, random error was relatively large, with standard deviations (and percentage coefficients of variation) averaging only 0.36 cm (and 3.8%), but varying between 0.14 and 0.61 cm (and 1.9 and 7.1%). However, at the stand scale, sampling errors (i.e. how well individual trees or shrubs selected for measurement of diameter represented the true stand population in terms of the average and distribution of diameter) generally had at least a tenfold greater influence on random errors in basal area estimates than errors in diameter measurements. This supports the use of diameter measurement tools that have high efficiency, such as the SDG. Use of the SDG almost halved the time required for measurements compared to the diameter tape. Based on these findings, recommendations include the following: (i) use of a tape to maximise accuracy when developing allometric models, or when monitoring relatively small changes in permanent sample plots (e.g. National Forest Inventories), noting that care is required in irregular-shaped, large-single-stemmed individuals, and (ii) use of a SDG to maximise efficiency when using inventory methods to assess basal area, and hence biomass or wood volume, at the stand scale (i.e. in studies of impacts of management or site quality) where there are budgetary constraints, noting the importance of sufficient sample sizes to ensure that the population sampled represents the true population.

Phenotypic plasticity of Vaccinium meridionale (Ericaceae) in wild populations of mountain forests in Colombia.

PubMed

Ligarreto, Gustavo A; Patiño, Maria del Pilar; Magnitskiy, Stanislav V

2011-06-01

Vaccinium meridionale is a promising crop for the Andean region of South America and is currently available only in the wild. Spontaneous populations of this plant are found across the Colombian mountains, but very few published records on this plant morphology are available. A zonification study of V. meridionale was conducted in four principal areas of a low mountain forest of Colombia (Provinces of Boyacá, Cundinamarca, Santander and Nariño) in 2007. A total of 20 populations and 100 plants of V. meridionale were individually characterized and surveyed, using a list of 26 characters of morphological variables (9 quantitative and 17 qualitative characters). Our results indicated that natural populations of V. meridionale might be found in the tropical forest under a highly heterogeneous climate and microclimate conditions, at different mountain regions between 2 357 and 3 168masl. The shrubs of V. meridionale exhibited a high level of intra-population variation in several quantitative (plant height, stem diameter) and qualitative (growth habit, ramification density, presence of anthocyanins in stems) morphological characters, suggesting an environmentally induced phenotypic plasticity. Plant height, stem diameter and foliar density were the most variable morphological traits, with coefficients of variation higher than 50%. However, several quantitative characters of its reproductive potential, such as berry dimensions, rachis length and number of flowers per inflorescence, resulted with low plasticity with coefficients of variation lower than 30.2%, indicating that these characters were genetically determined. The highest correlation coefficients (p < 0.05) resulted to be between fruit length and fruit width (0.90), leaf length and leaf width (0.78), plant height and stem diameter (0.60), and inflorescence length and flowers number per inflorescence (0.57). The results suggest that an important genetic resource exists for this species in the wild. Low variation in fruit size, which constitutes a target trait for plant breeders, could be useful for selection of cultivars of V. meridionale. The results of this study could also be applied in conservation programs aimed to protect these diverse populations in the mountain forests of Colombia.

Radial variation in sap velocity as a function of stem diameter and sapwood thickness in yellow-poplar trees.

PubMed

Wullschleger, Stan D.; King, Anthony W.

2000-04-01

Canopy transpiration and forest water use are frequently estimated as the product of sap velocity and cross-sectional sapwood area. Few studies, however, have considered whether radial variation in sap velocity and the proportion of sapwood active in water transport are significant sources of uncertainty in the extrapolation process. Therefore, radial profiles of sap velocity were examined as a function of stem diameter and sapwood thickness for yellow-poplar (Liriodendron tulipifera L.) trees growing on two adjacent watersheds in eastern Tennessee. The compensation heat pulse velocity technique was used to quantify sap velocity at four equal-area depths in 20 trees that ranged in stem diameter from 15 to 69 cm, and in sapwood thickness from 2.1 to 14.8 cm. Sap velocity was highly dependent on the depth of probe insertion into the sapwood. Rates of sap velocity were greatest for probes located in the two outer sapwood annuli (P1 and P2) and lowest for probes in closest proximity to the heartwood (P3 and P4). Relative sap velocities averaged 0.98 at P1, 0.66 at P2, 0.41 at P3 and 0.35 at P4. Tree-specific sap velocities measured at each of the four probe positions, divided by the maximum sap velocity measured (usually at P1 or P2), indicated that the fraction of sapwood functional in water transport (f(S)) varied between 0.49 and 0.96. There was no relationship between f(S) and sapwood thickness, or between f(S) and stem diameter. The fraction of functional sapwood averaged 0.66 +/- 0.13 for trees on which radial profiles were determined. No significant depth-related differences were observed for sapwood density, which averaged 469 kg m(-3) across all four probe positions. There was, however, a significant decline in sapwood water content between the two outer probe positions (1.04 versus 0.89 kg kg(-1)). This difference was not sufficient to account for the observed radial variation in sap velocity. A Monte-Carlo analysis indicated that the standard error in estimated mean f(S) declined rapidly with increasing sample size. At n = 10, the coefficient of variation in mean f(S) was 7% and at n = 15 it was slightly less than 5%. These observations indicate that radial variation in sap velocity is an important, albeit often overlooked, source of uncertainty in the scaling process. Failure to recognize that not all sapwood is functional in water transport will introduce systematic bias into estimates of both tree and stand water use. Future studies should devise sampling strategies for assessing radial variation in sap velocity and such strategies should be used to identify the magnitude of this variation in a range of non-, diffuse- and ring-porous trees.

[Effects of elevated ozone on Pinus armandii growth: a simulation study with open-top chamber].

PubMed

Liu, Chang-Fu; Liu, Chen; He, Xing-Yuan; Ruan, Ya-Nan; Xu, Sheng; Chen, Zhen-Ju; Peng, Jun-Jie; Li, Teng

2013-10-01

By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the growth 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 growth of P. armandii significantly, with the annual growth of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual growth of tree-ring width and the annual ring 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 growth (NDVI).

Relationships of tree height and diameter at breast height revisited: analyses of stem growth using 20-year data of an even-aged Chamaecyparis obtusa stand

PubMed Central

Sumida, Akihiro; Miyaura, Tomiyasu; Torii, Hitoshi

2013-01-01

Stem diameter at breast height (DBH) and tree height (H) are commonly used measures of tree growth. We examined patterns of height growth and diameter growth along a stem using a 20-year record of an even-aged hinoki cypress (Chamaecyparis obtusa (Siebold & Zucc.) Endl.) stand. In the region of the stem below the crown (except for the butt swell), diameter growth rates (ΔD) at different heights tended to increase slightly from breast height upwards. This increasing trend was pronounced in suppressed trees, but not as much as the variation in ΔD among individual trees. Hence, ΔD below the crown can be regarded as generally being represented by the DBH growth rate (ΔDBH) of a tree. Accordingly, the growth rate of the stem cross-sectional area increased along the stem upwards in suppressed trees, but decreased in dominant trees. The stem diameter just below the crown base (DCB), the square of which is an index of the amount of leaves on a tree, was an important factor affecting ΔDBH. DCB also had a strong positive relationship with crown length. Hence, long-term changes in the DCB of a tree were associated with long-term changes in crown length, determined by the balance between the height growth rate (ΔH) and the rising rate of the crown base (ΔHCB). Within the crown, ΔD's were generally greater than the rates below the crown. Even dying trees (ΔD ≈ 0 below the crown) maintained ΔD > 0 within the crown and ΔH > 0 until about 5 years before death. This growth within the crown may be related to the need to produce new leaves to compensate for leaves lost owing to the longevity of the lower crown. These results explain the different time trajectories in DBH–H relationships among individual trees, and also the long-term changes in the DBH–H relationships. The view that a rise in the crown base is strongly related to leaf turnover helps to interpret DBH–H relationships. PMID:23303367

Vertical gradients and seasonal variation in stem CO2 efflux within a Norway spruce stand.

PubMed

Tarvainen, Lasse; Räntfors, Mats; Wallin, Göran

2014-05-01

Stem CO2 efflux is known to vary seasonally and vertically along tree stems. However, annual tree- and stand-scale efflux estimates are commonly based on measurements made only a few times a year, during daytime and at breast height. In this study, the effect of these simplifying assumptions on annual efflux estimates and their influence on the estimates of the importance of stems in stand-scale carbon cycling are evaluated. In order to assess the strength of seasonal, diurnal and along-stem variability in CO2 efflux, half-hourly measurements were carried out at three heights on three mature Norway spruce (Picea abies (L.) Karst.) trees over a period of 3 years. Making the common assumption of breast height efflux rates being representative of the entire stem was found to result in underestimations of 10-17% in the annual tree-scale CO2 efflux. Upscaling using only daytime measurements from breast height increased the underestimation to 15-20%. Furthermore, the results show that the strength of the vertical gradient varies seasonally, being strongest in the early summer and non-existent during the cool months. The observed seasonality in the vertical CO2 efflux gradient could not be explained by variation in stem temperature, temperature response of the CO2 efflux (Q10), outer-bark permeability, CO2 transport in the xylem or CO2 release from the phloem. However, the estimated CO2 concentration immediately beneath the bark was considerably higher in the upper stem during the main period of diameter growth, coinciding with the strongest vertical efflux gradient. These results suggest that higher growth rates in the upper stem are the main cause for the observed vertical variation in the stem CO2 effluxes. Furthermore, the results indicate that accounting for the vertical efflux variation is essential for assessments of the importance of stems in stand-scale carbon cycling. © The Author 2014. Published by Oxford University Press. All rights reserved.

Comparing partial cutttng practices in central Appalachian hardwoods

Treesearch

G.W. Miller; H.C. Smith

1991-01-01

Variations of diameter-limit and perhaps single-tree selection harvesting are used to regenerate and manage central Appalachian hardwood sawtimber stands. In practice, these methods differ in terms of cut rules, control of stand structure, and cultural treatment of immature stems. Preliminary information is provided to compare the effect of two differing harvest...

Five willow varieties cultivated across diverse field environments reveal stem density variation associated with high tension wood abundance

PubMed Central

Berthod, Nicolas; Brereton, Nicholas J. B.; Pitre, Frédéric E.; Labrecque, Michel

2015-01-01

Sustainable and inexpensive production of biomass is necessary to make biofuel production feasible, but represents a challenge. Five short rotation coppice willow cultivars, selected for high biomass yield, were cultivated on sites at four diverse regions of Quebec in contrasting environments. Wood composition and anatomical traits were characterized. Tree height and stem diameter were measured to evaluate growth performance of the cultivars according to the diverse pedoclimatic conditions. Each cultivar showed very specific responses to its environment. While no significant variation in lignin content was observed between sites, there was variation between cultivars. Surprisingly, the pattern of substantial genotype variability in stem density was maintained across all sites. However, wood anatomy did differ between sites in a cultivar (producing high and low density wood), suggesting a probable response to an abiotic stress. Furthermore, twice as many cellulose-rich G-fibers, comprising over 50% of secondary xylem, were also found in the high density wood, a finding with potential to bring higher value to the lignocellulosic bioethanol industry. PMID:26583024

Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models.

PubMed

Johnson, Michelle O; Galbraith, David; Gloor, Manuel; De Deurwaerder, Hannes; Guimberteau, Matthieu; Rammig, Anja; Thonicke, Kirsten; Verbeeck, Hans; von Randow, Celso; Monteagudo, Abel; Phillips, Oliver L; Brienen, Roel J W; Feldpausch, Ted R; Lopez Gonzalez, Gabriela; Fauset, Sophie; Quesada, Carlos A; Christoffersen, Bradley; Ciais, Philippe; Sampaio, Gilvan; Kruijt, Bart; Meir, Patrick; Moorcroft, Paul; Zhang, Ke; Alvarez-Davila, Esteban; Alves de Oliveira, Atila; Amaral, Ieda; Andrade, Ana; Aragao, Luiz E O C; Araujo-Murakami, Alejandro; Arets, Eric J M M; Arroyo, Luzmila; Aymard, Gerardo A; Baraloto, Christopher; Barroso, Jocely; Bonal, Damien; Boot, Rene; Camargo, Jose; Chave, Jerome; Cogollo, Alvaro; Cornejo Valverde, Fernando; Lola da Costa, Antonio C; Di Fiore, Anthony; Ferreira, Leandro; Higuchi, Niro; Honorio, Euridice N; Killeen, Tim J; Laurance, Susan G; Laurance, William F; Licona, Juan; Lovejoy, Thomas; Malhi, Yadvinder; Marimon, Bia; Marimon, Ben Hur; Matos, Darley C L; Mendoza, Casimiro; Neill, David A; Pardo, Guido; Peña-Claros, Marielos; Pitman, Nigel C A; Poorter, Lourens; Prieto, Adriana; Ramirez-Angulo, Hirma; Roopsind, Anand; Rudas, Agustin; Salomao, Rafael P; Silveira, Marcos; Stropp, Juliana; Ter Steege, Hans; Terborgh, John; Thomas, Raquel; Toledo, Marisol; Torres-Lezama, Armando; van der Heijden, Geertje M F; Vasquez, Rodolfo; Guimarães Vieira, Ima Cèlia; Vilanova, Emilio; Vos, Vincent A; Baker, Timothy R

2016-12-01

Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs. © 2016 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Size of Douglas-fir trees in relation to distance from a mixed red alder - Douglas-fir stand

Treesearch

R.E. Miller; D.L. Reukema; T.A. Max

1993-01-01

Variation in diameter, height, and stem volume of 57-year-old Douglas-fir(Pseudotsuga menziesii var. menziesii (Mirb.) Franco) was related to distance of these trees from a 27 m wide strip in the same Douglas-fir plantation that had been interplanted with red alder (Alnus rubra Bong.). Within the...

Crown-Diameter Prediction Models for 87 Species of Stand-Grown Trees in the Eastern United States

Treesearch

William A. Bechtold

2003-01-01

The mean crown diameters of stand-grown trees were modeled as a function of stem diameter, live-crown ratio, stand basal area, latitude, longitude, elevation, and Hopkins bioclimatic index for 87 tree species in the eastern United States. Stem diameter was statistically significant in all models, and a quadratic term for stem diameter was required for some species....

Effect of Gamma Rays on Sophora davidii and Detection of DNA Polymorphism through ISSR Marker

PubMed Central

Wang, Puchang; Mo, Bentian; Luo, Tianqiong

2017-01-01

Sophora davidii (Franch.) Kom. ex Pavol is an important medicinal plant and a feeding scrub with ecological value. The effects of different gamma irradiation doses (20–140 Kr) on seed germination and seedling morphology were investigated in S. davidii, and intersimple sequence repeat (ISSR) markers were used to identify the DNA polymorphism among mutants. Significant variations were observed for seed germination, stem diameter, and number of branches per plant. The improved agronomic traits, such as stem diameter and number of branches per plant, were recorded at 80 Kr dose and 20 Kr dose for seed germination. ISSR analysis generated in total 183 scorable fragments, of which 94 (51.37%) were polymorphic. The percentage of polymorphism ranged from 14.29 to 93.33 with an average of 45.69%. Jaccard's coefficients of dissimilarity varied from 0.6885 to 1.000, indicative of the level of genetic variation among the mutants. The constructed dendrogram grouped the entities into five clusters. Consequently, it was concluded that gamma rays irradiation of seeds generates a sufficient number of induced mutations and that ISSR analysis offered a useful molecular marker for the identification of mutants. PMID:28612030

Evaluation of stem rot in 339 Bornean tree species: implications of size, taxonomy, and soil-related variation for aboveground biomass estimates

NASA Astrophysics Data System (ADS)

Heineman, K. D.; Russo, S. E.; Baillie, I. C.; Mamit, J. D.; Chai, P. P.-K.; Chai, L.; Hindley, E. W.; Lau, B.-T.; Tan, S.; Ashton, P. S.

2015-10-01

Fungal decay of heart wood creates hollows and areas of reduced wood density within the stems of living trees known as stem rot. Although stem rot is acknowledged as a source of error in forest aboveground biomass (AGB) estimates, there are few data sets available to evaluate the controls over stem rot infection and severity in tropical forests. Using legacy and recent data from 3180 drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of stem rot in a total of 339 tree species, and related variation in stem rot with tree size, wood density, taxonomy, and species' soil association, as well as edaphic conditions. Predicted stem rot frequency for a 50 cm tree was 53 % of felled, 39 % of drilled, and 28 % of cored stems, demonstrating differences among methods in rot detection ability. The percent stem volume infected by rot, or stem rot severity, ranged widely among trees with stem rot infection (0.1-82.8 %) and averaged 9 % across all trees felled. Tree taxonomy explained the greatest proportion of variance in both stem rot frequency and severity among the predictors evaluated in our models. Stem rot frequency, but not severity, increased sharply with tree diameter, ranging from 13 % in trees 10-30 cm DBH to 54 % in stems ≥ 50 cm DBH across all data sets. The frequency of stem rot increased significantly in soils with low pH and cation concentrations in topsoil, and stem rot was more common in tree species associated with dystrophic sandy soils than with nutrient-rich clays. When scaled to forest stands, the maximum percent of stem biomass lost to stem rot varied significantly with soil properties, and we estimate that stem rot reduces total forest AGB estimates by up to 7 % relative to what would be predicted assuming all stems are composed strictly of intact wood. This study demonstrates not only that stem rot is likely to be a significant source of error in forest AGB estimation, but also that it strongly covaries with tree size, taxonomy, habitat association, and soil resources, underscoring the need to account for tree community composition and edaphic variation in estimating carbon storage in tropical forests.

Largest-Crown- Width Prediction Models for 53 Species in the Western United States

Treesearch

William A. Bechtold

2004-01-01

The mean crown diameters of stand-grown trees 5.0-in. dbh and larger were modeled as a function of stem diameter, live-crown ratio, stand-level basal area, latitude, longitude, elevation, and Hopkins bioclimatic index for 53 tree species in the western United States. Stem diameter was statistically significant in all models, and a quadratic term for stem diameter was...

Elevational change in woody tissue CO2 efflux in a tropical mountain rain forest in southern Ecuador.

PubMed

Zach, Alexandra; Horna, Viviana; Leuschner, Christoph

2008-01-01

Much uncertainty exists about the magnitude of woody tissue respiration and its environmental control in highly diverse tropical moist forests. In a tropical mountain rain forest in southern Ecuador, we measured the apparent diurnal gas exchange of stems and coarse roots (diameter 1-4 cm) of trees from representative families along an elevational transect with plots at 1050, 1890 and 3050 m a.s.l. Mean air temperatures were 20.8, 17.2 and 10.6 degrees C, respectively. Stem and root CO(2) efflux of 13 to 21 trees per stand from dominant families were investigated with an open gas exchange system while stand microclimate was continuously monitored. Substantial variation in respiratory activity among and within species was found at all sites. Mean daily CO(2) release rates from stems declined 6.6-fold from 1.38 micromol m(-2) s(-1) at 1050 m to 0.21 micromol m(-2) s(-1) at 3050 m. Mean daily CO(2) release from coarse roots decreased from 0.35 to 0.20 micromol m(-2) s(-1) with altitude, but the differences were not significant. There was, thus, a remarkable shift from a high ratio of stem to coarse root respiration rates at the lowest elevation to an apparent equivalence of stem and coarse root CO(2) efflux rates at the highest elevation. We conclude that stem respiration, but not root respiration, greatly decreases with elevation in this transect, coinciding with a substantial decrease in relative stem diameter increment and a large increase in fine and coarse root biomass production with elevation.

Variations in xylem embolism susceptibility under drought between intact saplings of three walnut species.

PubMed

Knipfer, Thorsten; Barrios-Masias, Felipe H; Cuneo, Italo F; Bouda, Martin; Albuquerque, Caetano P; Brodersen, Craig R; Kluepfel, Daniel A; McElrone, Andrew J

2018-05-30

A germplasm collection containing varied Juglans genotypes holds potential to improve drought resistance of plant materials for commercial production. We used X-ray computed microtomography to evaluate stem xylem embolism susceptibility/repair in relation to vessel anatomical features (size, arrangement, connectivity and pit characteristics) in 2-year-old saplings of three Juglans species. In vivo analysis revealed interspecific variations in embolism susceptibility among Juglans microcarpa, J. hindsii (both native to arid habitats) and J. ailantifolia (native to mesic habitats). Stem xylem of J. microcarpa was more resistant to drought-induced embolism as compared with J. hindsii and J. ailantifolia (differences in embolism susceptibility among older and current year xylem were not detected in any species). Variations in most vessel anatomical traits were negligible among the three species; however, we detected substantial interspecific differences in intervessel pit characteristics. As compared with J. hindsii and J. ailantifolia, low embolism susceptibility in J. microcarpa was associated with smaller pit size in larger diameter vessels, a smaller area of the shared vessel wall occupied by pits, lower pit frequency and no changes in pit characteristics as vessel diameters increased. Changes in amount of embolized vessels following 40 days of re-watering were minor in intact saplings of all three species highlighting that an embolism repair mechanism did not contribute to drought recovery. In conclusion, our data indicate that interspecific variations in drought-induced embolism susceptibility are associated with species-specific pit characteristics, and these traits may provide a future target for breeding efforts aimed at selecting walnut germplasm with improved drought resistance.

[Stem sap flow and water consumption of Tamarix ramosissima in hinterland of Taklimakan Desert].

PubMed

Xu, Hao; Zhang, Xi-Ming; Yan, Hai-Long; Yao, Shi-Jun

2007-04-01

From April to November 2005, the stem sap flow and water consumption of Tamarix ramosissima in the hinterland of Taklimakan Desert was measured by Flow-32 System. The results showed that, in the extremely arid hinterland of Taklimakan Desert and under enough water supply, the average daily water consumption of T. ramosissima with a stem diameter of 3.5 cm and 2.0 cm was 6.322 kg and 1.179 kg, respectively in one growth season. The stem sap flow of T. ramosissima presented a single-peaked curve, with an obvious day and night variation rhythm and fluctuated with environment factors. Under enough water supply, the environmenal factors such as total radiation, wind speed and air temperature were the main factors affecting the stem sap flow, and the dynamics of stem sap flow could be predicted by the liner regression model based on total radiation and wind speed. Because of the extremely arid environment and enough water supply, T. ramosissima had a relatively higher stem sap flow rate and a great water consumption.

Post-veraison irreversible stem shrinkage in grapevine (Vitis vinifera) is caused by periderm formation.

PubMed

Van de Wal, Bart A E; Leroux, Olivier; Steppe, Kathy

2018-05-01

Grapevines are characterized by a period of irreversible stem shrinkage around the onset of ripening of the grape berries. Since this shrinkage is unrelated to meteorological conditions or drought, it is often suggested that it is caused by the increased sink strength of the grape berries during this period. However, no studies so far have experimentally investigated the mechanisms underlying this irreversible stem shrinkage. We therefore combined continuous measurements of stem diameter variations and histology of potted 2-year-old grapevines (Vitis vinifera L. 'Boskoop Glory'). Sink strength was altered by pruning all grape clusters (treatment P), while non-pruned grapevines served as control (treatment C). Unexpectedly, our results showed irreversible post-veraison stem shrinkage in both treatments, suggesting that the shrinkage is not linked to grape berry sink strength. Anatomical analysis indicated that the shrinkage is the result of the formation of successive concentric periderm layers, and the subsequent dehydration and compression of the older bark tissues, an anatomical feature that is characteristic of Vitis stems. Stem shrinkage is hence unrelated to grape berry development, in contrast to what has been previously suggested.

Posterior brain in fetuses with open spina bifida at 11 to 13 weeks.

PubMed

Lachmann, Robert; Chaoui, Rabih; Moratalla, Jose; Picciarelli, Gemma; Nicolaides, Kypros H

2011-01-01

To measure the changes in the posterior fossa in first-trimester fetuses with open spina bifida (OSB). The brain stem diameter and brain stem to occipital bone (BSOB) diameter were measured in stored images of the mid-sagittal view of the fetal face at 11(+0) to 13(+6) weeks from 30 fetuses with OSB and 1000 normal controls. In the control group, the brain stem and BSOB diameter increased significantly with crown-rump length (CRL) and the brain stem to BSOB ratio decreased. In the spina bifida group, the brain stem diameter was above the 95th percentile of the control group in 29 (96.7%) cases, the BSOB diameter was below the 5th percentile in 26 (86.7%) and the brain stem to BSOB ratio was above the 95th percentile in all cases. At 11 to 13 weeks the majority of fetuses with OSB have measurable abnormalities in the posterior brain.

50 CFR 665.165 - Size restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54 cm) from the... from any precious coral permit area must have attained either a minimum stem diameter of 1 inch (2.54...

50 CFR 665.265 - Size restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54 cm) from the... from any precious coral permit area must have attained either a minimum stem diameter of 1 inch (2.54...

Estimation of Tree Position and STEM Diameter Using Simultaneous Localization and Mapping with Data from a Backpack-Mounted Laser Scanner

NASA Astrophysics Data System (ADS)

Holmgren, J.; Tulldahl, H. M.; Nordlöf, J.; Nyström, M.; Olofsson, K.; Rydell, J.; Willén, E.

2017-10-01

A system was developed for automatic estimations of tree positions and stem diameters. The sensor trajectory was first estimated using a positioning system that consists of a low precision inertial measurement unit supported by image matching with data from a stereo-camera. The initial estimation of the sensor trajectory was then calibrated by adjustments of the sensor pose using the laser scanner data. Special features suitable for forest environments were used to solve the correspondence and matching problems. Tree stem diameters were estimated for stem sections using laser data from individual scanner rotations and were then used for calibration of the sensor pose. A segmentation algorithm was used to associate stem sections to individual tree stems. The stem diameter estimates of all stem sections associated to the same tree stem were then combined for estimation of stem diameter at breast height (DBH). The system was validated on four 20 m radius circular plots and manual measured trees were automatically linked to trees detected in laser data. The DBH could be estimated with a RMSE of 19 mm (6 %) and a bias of 8 mm (3 %). The calibrated sensor trajectory and the combined use of circle fits from individual scanner rotations made it possible to obtain reliable DBH estimates also with a low precision positioning system.

Role of tree size in moist tropical forest carbon cycling and water deficit responses.

PubMed

Meakem, Victoria; Tepley, Alan J; Gonzalez-Akre, Erika B; Herrmann, Valentine; Muller-Landau, Helene C; Wright, S Joseph; Hubbell, Stephen P; Condit, Richard; Anderson-Teixeira, Kristina J

2017-06-06

Drought disproportionately affects larger trees in tropical forests, but implications for forest composition and carbon (C) cycling in relation to dry season intensity remain poorly understood. In order to characterize how C cycling is shaped by tree size and drought adaptations and how these patterns relate to spatial and temporal variation in water deficit, we analyze data from three forest dynamics plots spanning a moisture gradient in Panama that have experienced El Niño droughts. At all sites, aboveground C cycle contributions peaked below 50-cm stem diameter, with stems ≥ 50 cm accounting for on average 59% of live aboveground biomass, 45% of woody productivity and 49% of woody mortality. The dominance of drought-avoidance strategies increased interactively with stem diameter and dry season intensity. Although size-related C cycle contributions did not vary systematically across the moisture gradient under nondrought conditions, woody mortality of larger trees was disproportionately elevated under El Niño drought stress. Thus, large (> 50 cm) stems, which strongly mediate but do not necessarily dominate C cycling, have drought adaptations that compensate for their more challenging hydraulic environment, particularly in drier climates. However, these adaptations do not fully buffer the effects of severe drought, and increased large tree mortality dominates ecosystem-level drought responses. © 2017 Smithsonian. Institute New Phytologist © 2017 New Phytologist Trust.

Direct uptake of canopy rainwater causes turgor-driven growth spurts in the mangrove Avicennia marina.

PubMed

Steppe, Kathy; Vandegehuchte, Maurits W; Van de Wal, Bart A E; Hoste, Pieter; Guyot, Adrien; Lovelock, Catherine E; Lockington, David A

2018-03-17

Mangrove forests depend on a dense structure of sufficiently large trees to fulfil their essential functions as providers of food and wood for animals and people, CO2 sinks and protection from storms. Growth of these forests is known to be dependent on the salinity of soil water, but the influence of foliar uptake of rainwater as a freshwater source, additional to soil water, has hardly been investigated. Under field conditions in Australia, stem diameter variation, sap flow and stem water potential of the grey mangrove (Avicennia marina (Forssk.) Vierh.) were simultaneously measured during alternating dry and rainy periods. We found that sap flow in A. marina was reversed, from canopy to roots, during and shortly after rainfall events. Simultaneously, stem diameters rapidly increased with growth rates up to 70 μm h-1, which is about 25-75 times the normal growth rate reported in temperate trees. A mechanistic tree model was applied to provide evidence that A. marina trees take up water through their leaves, and that this water contributes to turgor-driven stem growth. Our results indicate that direct uptake of freshwater by the canopy during rainfall supports mangrove tree growth and serve as a call to consider this water uptake pathway if we aspire to correctly assess influences of changing rainfall patterns on mangrove tree growth.

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis

PubMed Central

Georgiou, CS; Evangelou, KG; Theodorou, EG; Provatidis, CG; Megas, PD

2012-01-01

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed. PMID:23284597

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis.

PubMed

Georgiou, Cs; Evangelou, Kg; Theodorou, Eg; Provatidis, Cg; Megas, Pd

2012-01-01

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed.

Predicting performance for ecological restoration: A case study using Spartina altemiflora

USGS Publications Warehouse

Travis, S.E.; Grace, J.B.

2010-01-01

The success of population-based ecological restoration relies on the growth and reproductive performance of selected donor materials, whether consisting of whole plants or seed. Accurately predicting performance requires an understanding of a variety of underlying processes, particularly gene flow and selection, which can be measured, at least in part, using surrogates such as neutral marker genetic distances and simple latitudinal effects. Here we apply a structural equation modeling approach to understanding and predicting performance in a widespread salt marsh grass, Spartina alterniflora, commonly used for ecological restoration throughout its native range in North America. We collected source materials from throughout this range, consisting of eight clones each from 23 populations, for transplantation to a common garden site in coastal Louisiana and monitored their performance. We modeled performance as a latent process described by multiple indicator variables (e.g., clone diameter, stem number) and estimated direct and indirect influences of geographic and genetic distances on performance. Genetic distances were determined by comparison of neutral molecular markers with those from a local population at the common garden site. Geographic distance metrics included dispersal distance (the minimum distance over water between donor and experimental sites) and latitude. Model results indicate direct effects of genetic distance and latitude on performance variation among the donor sites. Standardized effect strengths indicate that performance was roughly twice as sensitive to variation in genetic distance as to latitudinal variation. Dispersal distance had an indirect influence on performance through effects on genetic distance, indicating a typical pattern of genetic isolation by distance. Latitude also had an indirect effect on genetic distance through its linear relationship with dispersal distance. Three performance indicators had significant loadings on performance alone (mean clone diameter, mean number of stems, mean number of inflorescences), while the performance indicators mean stem height and mean stem width were also influenced by latitude. We suggest that dispersal distance and latitude should provide an adequate means of predicting performance in future S. alterniflora restorations and propose a maximum sampling distance of 300 km (holding latitude constant) to avoid the sampling of inappropriate ecotypes. ?? 2010 by the Ecological Society of America.

Tree Circumference Dynamics in Four Forests Characterized Using Automated Dendrometer Bands

PubMed Central

McMahon, Sean M.; Detto, Matteo; Lutz, James A.; Davies, Stuart J.; Chang-Yang, Chia-Hao; Anderson-Teixeira, Kristina J.

2016-01-01

Stem diameter is one of the most commonly measured attributes of trees, forming the foundation of forest censuses and monitoring. Changes in tree stem circumference include both irreversible woody stem growth and reversible circumference changes related to water status, yet these fine-scale dynamics are rarely leveraged to understand forest ecophysiology and typically ignored in plot- or stand-scale estimates of tree growth and forest productivity. Here, we deployed automated dendrometer bands on 12–40 trees at four different forested sites—two temperate broadleaf deciduous, one temperate conifer, and one tropical broadleaf semi-deciduous—to understand how tree circumference varies on time scales of hours to months, how these dynamics relate to environmental conditions, and whether the structure of these variations might introduce substantive error into estimates of woody growth. Diurnal stem circumference dynamics measured over the bark commonly—but not consistently—exhibited daytime shrinkage attributable to transpiration-driven changes in stem water storage. The amplitude of this shrinkage was significantly correlated with climatic variables (daily temperature range, vapor pressure deficit, and radiation), sap flow and evapotranspiration. Diurnal variations were typically <0.5 mm circumference in amplitude and unlikely to be of concern to most studies of tree growth. Over time scales of multiple days, the bands captured circumference increases in response to rain events, likely driven by combinations of increased stem water storage and bark hydration. Particularly at the tropical site, these rain responses could be quite substantial, ranging up to 1.5 mm circumference expansion within 48 hours following a rain event. We conclude that over-bark measurements of stem circumference change sometimes correlate with but have limited potential for directly estimating daily transpiration, but that they can be valuable on time scales of days to weeks for characterizing changes in stem growth and hydration. PMID:28030646

Spatial Characteristics of Tree Diameter Distributions in a Temperate Old-Growth Forest

PubMed Central

Zhao, Xiuhai; von Gadow, Klaus

2013-01-01

This contribution identifies spatial characteristics of tree diameter in a temperate forest in north-eastern China, based on a fully censused observational study area covering 500×600 m. Mark correlation analysis with three null hypothesis models was used to determine departure from expectations at different neighborhood distances. Tree positions are clumped at all investigated scales in all 37 studied species, while the diameters of most species are spatially negatively correlated, especially at short distances. Interestingly, all three cases showing short-distance attraction of dbh marks are associated with light-demanding shrub species. The short-distance attraction of dbh marks indicates spatially aggregated cohorts of stems of similar size. The percentage of species showing significant dbh suppression peaked at a 4 m distance under the heterogeneous Poisson model. At scales exceeding the peak distance, the percentage of species showing significant dbh suppression decreases sharply with increasing distances. The evidence from this large observational study shows that some of the variation of the spatial characteristics of tree diameters is related variations of topography and soil chemistry. However, an obvious interpretation of this result is still lacking. Thus, removing competitors surrounding the target trees is an effective way to avoid neighboring competition effects reducing the growth of valuable target trees in forest management practice. PMID:23527066

Spatial characteristics of tree diameter distributions in a temperate old-growth forest.

PubMed

Zhang, Chunyu; Wei, Yanbo; Zhao, Xiuhai; von Gadow, Klaus

2013-01-01

This contribution identifies spatial characteristics of tree diameter in a temperate forest in north-eastern China, based on a fully censused observational study area covering 500×600 m. Mark correlation analysis with three null hypothesis models was used to determine departure from expectations at different neighborhood distances. Tree positions are clumped at all investigated scales in all 37 studied species, while the diameters of most species are spatially negatively correlated, especially at short distances. Interestingly, all three cases showing short-distance attraction of dbh marks are associated with light-demanding shrub species. The short-distance attraction of dbh marks indicates spatially aggregated cohorts of stems of similar size. The percentage of species showing significant dbh suppression peaked at a 4 m distance under the heterogeneous Poisson model. At scales exceeding the peak distance, the percentage of species showing significant dbh suppression decreases sharply with increasing distances. The evidence from this large observational study shows that some of the variation of the spatial characteristics of tree diameters is related variations of topography and soil chemistry. However, an obvious interpretation of this result is still lacking. Thus, removing competitors surrounding the target trees is an effective way to avoid neighboring competition effects reducing the growth of valuable target trees in forest management practice.

Cancer stem cells and cell size: A causal link?

PubMed

Li, Qiuhui; Rycaj, Kiera; Chen, Xin; Tang, Dean G

2015-12-01

The majority of normal animal cells are 10-20 μm in diameter. Many signaling mechanisms, notably PI3K/Akt/mTOR, Myc, and Hippo pathways, tightly control and coordinate cell growth, cell size, cell division, and cell number during homeostasis. These regulatory mechanisms are frequently deregulated during tumorigenesis resulting in wide variations in cell sizes and increased proliferation in cancer cells. Here, we first review the evidence that primitive stem cells in adult tissues are quiescent and generally smaller than their differentiated progeny, suggesting a correlation between small cell sizes with the stemness. Conversely, increased cell size positively correlates with differentiation phenotypes. We then discuss cancer stem cells (CSCs) and present some evidence that correlates cell sizes with CSC activity. Overall, a causal link between CSCs and cell size is relatively weak and remains to be rigorously assessed. In the future, optimizing methods for isolating cells based on size should help elucidate the connection between cancer cell size and CSC characteristics. Copyright © 2015 Elsevier Ltd. All rights reserved.

Becoming less tolerant with age: sugar maple, shade, and ontogeny.

PubMed

Sendall, Kerrie M; Lusk, Christopher H; Reich, Peter B

2015-12-01

Although shade tolerance is often assumed to be a fixed trait, recent work suggests ontogenetic changes in the light requirements of tree species. We determined the influence of gas exchange, biomass distribution, and self-shading on ontogenetic variation in the instantaneous aboveground carbon balance of Acer saccharum. We quantified the aboveground biomass distributions of 18 juveniles varying in height and growing in low light in a temperate forest understory in Minnesota, USA. Gas exchange rates of leaf and stem tissues were measured, and the crown architecture of each individual was quantified. The YPLANT program was used to estimate the self-shaded fraction of each crown and to model net leaf-level carbon gain. Leaf respiration and photosynthesis per gram of leaf tissue increased with plant size. In contrast, stem respiration rates per gram of stem tissue declined, reflecting a shift in the distribution of stem diameter sizes from smaller (with higher respiration) to larger diameter classes. However, these trends were outweighed by ontogenetic increases in self-shading (which reduces the net photosynthesis realized) and stem mass fraction (which increases the proportion of purely respiratory tissue) in terms of influence on net carbon exchange. As a result, net carbon gain per gram of aboveground plant tissue declined with increasing plant size, and the instantaneous aboveground light compensation point increased. When estimates of root respiration were included to model whole-plant carbon gain and light compensation points, relationships with plant size were even more pronounced. Our findings show how an interplay of gas exchange, self-shading, and biomass distribution shapes ontogenetic changes in shade tolerance.

Estimating root collar diameter growth for multi-stem western woodland tree species on remeasured forest inventory and analysis plots

Treesearch

Michael T. Thompson; Maggie. Toone

2012-01-01

Tree diameter growth models are widely used in many forestry applications, often to predict tree size at a future point in time. Also, there are instances where projections of past diameters are needed. An individual tree model has been developed to estimate diameter growth of multi-stem woodland tree species where the diameter is measured at root collar. The model was...

Effects of stem size on stem respiration and its flux components in yellow-poplar (Liriodendron tulipifera L.) trees.

PubMed

Fan, Hailan; McGuire, Mary Anne; Teskey, Robert O

2017-11-01

Carbon dioxide (CO2) released from respiring cells in the stems of trees (RS) can diffuse radially to the atmosphere (EA) or dissolve in xylem sap and move internally in the tree (FT). Previous studies have observed that EA decreases as stem or branch diameter increases, but the cause of this relationship has not been determined, nor has the relationship been confirmed between stem diameter and RS, which includes both EA and FT. In this study, for the first time the mass balance technique was used to estimate RS of stems of Liriodendron tulipifera L. trees of different diameters, ranging from 16 to 60 cm, growing on the same site. The magnitude of the component fluxes scaled with tree size. Among the five trees, the contribution of EA to RS decreased linearly with increasing stem diameter and sapwood area while the contribution of FT to RS increased linearly with stem diameter and sapwood area. For the smallest tree EA was 86% of RS but it was only 46% of RS in the largest tree. As tree size increased a greater proportion of respired CO2 dissolved in sap and remained within the tree. Due to increase in FT with tree size, we observed that trees of different sizes had the same RS even though they had different EA. This appears to explain why the EA of stems and branches decreases as their size increases. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

50 CFR 665.265 - Size restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.165 - Size restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.465 - Size restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.665 - Size restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... line measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch.... Live black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.665 - Size restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.265 - Size restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.465 - Size restrictions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.165 - Size restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.165 - Size restrictions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.265 - Size restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.265 - Size restrictions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.465 - Size restrictions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.165 - Size restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.665 - Size restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... line measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch.... Live black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.665 - Size restrictions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... line measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch.... Live black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.465 - Size restrictions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.465 - Size restrictions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch (2.54... black coral harvested from any precious coral permit area must have attained either a minimum stem...

50 CFR 665.665 - Size restrictions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... line measurement taken from its base to its most distal extremity. The stem diameter of a living coral specimen shall be determined by measuring the greatest diameter of the stem at a point no less than 1 inch.... Live black coral harvested from any precious coral permit area must have attained either a minimum stem...

Conditioning a segmented stem profile model for two diameter measurements

Treesearch

Raymond L. Czaplewski; Joe P. Mcclure

1988-01-01

The stem profile model of Max and Burkhart (1976) is conditioned for dbh and a second upper stem measurement. This model was applied to a loblolly pine data set using diameter outside bark at 5.3m (i.e., height of 17.3 foot Girard form class) as the second upper stem measurement, and then compared to the original, unconditioned model. Variance of residuals was reduced...

The potential of the tree water potential.

PubMed

Steppe, Kathy

2018-06-12

Non-invasive quantification of tree water potential is one of the grand challenges for assessing the fate of trees and forests in the coming decades. Tree water potential is a robust and direct indicator of tree water status and is preferably used to track how trees, forests and vegetation in general respond to changes in climate and drought. In this issue of Tree Physiology, Dietrich et al. (2018) predict the daily canopy water potential of mature temperate trees from tree water deficit derived from stem diameter variation measurements.

Factors affecting diurnal stem contraction in young Douglas-fir

Treesearch

Warren D. Devine; Constance Harrington

2011-01-01

Diurnal fluctuation in a tree's stem diameter is a function of daily growth and of the tree's water balance, as water is temporarily stored in the relatively elastic outer cambial and phloem tissues. On a very productive site in southwestern Washington, U.S.A we used recording dendrometers to monitor stem diameter fluctuations of Douglas-fir at plantation...

Survival and growth of black walnut families after 7 years in West Virginia

Treesearch

G. W. Wendel; Donald E. Dorn; Donald E. Dorn

1985-01-01

Average survival, 7-year stem diameter, and stem diameter growth differed significantly among 34 black walnut families planted in West Virginia. Average total height, height growth, and diameter at breast height were not significantly different among families. Families were from seed collected in West Virginia, Pennsylvania, North Carolina, and Tennessee. The 7-year...

Toward Reconciliation of STEM and SAXS Data from Ionomers by Investigating Gold Nanoparticles

NASA Astrophysics Data System (ADS)

Benetatos, Nicholas; Smith, Brian; Heiney, Paul; Winey, Karen

2005-03-01

We have recently pioneered the use of scanning transmission electron microscopy (STEM) for direct, model independent imaging of the nano-scale morphology of ionomers. To date, the sizes of ionic aggregates determined in STEM experiments are inconsistent with SAXS data interpreted by the Yarusso-Cooper model. To address this discrepancy we have investigated a pair of model nanoparticles (11 and 55 atom Au clusters) with both STEM and SAXS. Using this model system we have improved our method of measuring nanometer scale objects and evaluated the importance of STEM probe size and specimen thickness. While the size of the STEM probe was inconsequential, specimen thicker than 50 nm showed significant depreciation of image quality, which limits our ability to accurately measure particle size. SAXS was performed on dilute suspensions of nanoparticles and fit using a monodisperse, hard-sphere form factor model. For Au11, STEM finds a diameter of 1.3 nm + .14 and SAXS finds a diameter of 1.4 nm. Similarly, both STEM and SAXS determine a diameter of 1.7 nm for Au55. Analysis of these model systems have allowed us to evaluate several factors of potential importance in reconciling STEM and SAXS data from ionomers.

Tropical Rain Forest Structure, Tree Growth and Dynamics along a 2700-m Elevational Transect in Costa Rica

PubMed Central

Clark, David B.; Hurtado, Johanna; Saatchi, Sassan S.

2015-01-01

Rapid biological changes are expected to occur on tropical elevational gradients as species migrate upslope or go extinct in the face of global warming. We established a series of 9 1-ha plots in old-growth tropical rainforest in Costa Rica along a 2700 m relief elevational gradient to carry out long-term monitoring of tropical rain forest structure, dynamics and tree growth. Within each plot we mapped, identified, and annually measured diameter for all woody individuals with stem diameters >10 cm for periods of 3-10 years. Wood species diversity peaked at 400-600 m and decreased substantially at higher elevations. Basal area and stem number varied by less than two-fold, with the exception of the 2800 m cloud forest summit, where basal area and stem number were approximately double that of lower sites. Canopy gaps extending to the forest floor accounted for <3% of microsites at all elevations. Height of highest crowns and the coefficient of variation of crown height both decreased with increasing elevation. Rates of turnover of individuals and of stand basal area decreased with elevation, but rates of diameter growth and stand basal area showed no simple relation to elevation. We discuss issues encountered in the design and implementation of this network of plots, including biased sampling, missing key meteorological and biomass data, and strategies for improving species-level research. Taking full advantage of the major research potential of tropical forest elevational transects will require sustaining and extending ground based studies, incorporation of new remotely-sensed data and data-acquisition platforms, and new funding models to support decadal research on these rapidly-changing systems. PMID:25856163

Metasequoia glyptostroboides and its Utility in Paleoecological Reconstruction of Eocene High Latitude Forests

NASA Astrophysics Data System (ADS)

Williams, C. J.; LePage, B. A.; Vann, D. R.; Johnson, A. H.

2001-05-01

Abundant fossil plant remains are preserved in the Eocene-aged deposits of the Buchanan Lake formation on Axel Heiberg Island, Nunavut, Canada. Intact leaf litter, logs, and stumps preserved in situ as mummified remains present an opportunity to determine forest composition, structure, and productivity of a Taxodiaceae-dominated forest that once grew north of the Arctic Circle (paleolatitude 75-80° N). We excavated 37 tree stems for dimensional analysis from mudstone and channel-sand deposits. Stem length ranged from 1.0 m to 14.8 m (average = 3.2 m). Stem diameter ranged from less than 10 cm to greater than 75 cm (average = 32.2 cm). All stem wood was tentatively identified to genus as Metasequoia sp. The diameters and parabolic shape of the preserved tree trunks indicate that the Metasequoia were about 39 m tall across a wide range of diameters. The allometric relationships we derived for modern Metasequoia (n=70) allowed independent predictions of Metasequoia height given the stand density and stump diameters of the fossil forest. The two height estimates of 40 and 40.5 m match the results obtained from measurements of the Eocene trees. We used stump diameter data (n =107, diameter > 20 cm) and an uniform canopy height of 39 m to calculate parabolic stem volume and stem biomass for a 0.22 ha area of fossil forest. Stem volume equaled 2065 m3 ha-1 and stem biomass equaled 560 Mg ha-1 . In the Eocene forest, as determined from length of stems that were free of protruding branches and from 7 exhumed tree tops, the uppermost 9 m of the trees carried live branches with foliage. In living conifers, branch weights and the amount of foliage carried by branches are well correlated with branch diameters measured where the branch joins the main stem. To determine the biomass in branches and foliage in the Eocene forest, we used relationships derived from large modern Metasequoia. Based on the regression of branch weight v. branch diameter (r2 = 0.97) and foliar biomass v. branch diameter (r2 = 0.91) for living Metasequoia and branch diameters of the Eocene trees, branch biomass of the Eocene trees was estimated to be 28 Mg ha-1 dry weight and foliar biomass (and annual foliar production for this deciduous conifer) of fossil Metasequoia was estimated to be 3.5 Mg ha-1 dry weight. Total standing biomass of the fossil forest was estimated to be 591 Mg ha-1 dry weight. On a stand-average basis, the annual ring width of the trees we sampled equaled 1.3 mm. Based on this ring width our preliminary estimate for the aboveground net primary productivity (NPP) of these forests is 5.9 Mg ha-1yr^{-1}$ (foliage production plus wood production). Thus, these were high biomass forests with moderate productivity typical of modern cool temperate forests similar in stature and total biomass to the modern old-growth forests of the Pacific Northwest (USA).

Distribution of diameter growth rates & clear stem lengths as a basis for selecting superior phonotypes

Treesearch

George R., Jr. Trimble; Donald W. Seegrist; Donald W. Seegrist

1970-01-01

This paper presents the joint distribution of diameter growth and length of clear stem for northern red oak (Querczls rzlbra L.). These data could be used in an actual tree-selection program for this species.

An external heat pulse method for measurement of sap flow through fruit pedicels, leaf petioles and other small-diameter stems.

PubMed

Clearwater, Michael J; Luo, Zhiwei; Mazzeo, Mariarosaria; Dichio, Bartolomeo

2009-12-01

The external heat ratio method is described for measurement of low rates of sap flow in both directions through stems and other plant organs, including fruit pedicels, with diameters up to 5 mm and flows less than 2 g h(-1). Calibration was empirical, with heat pulse velocity (v(h)) compared to gravimetric measurements of sap flow. In the four stem types tested (Actinidia sp. fruit pedicels, Schefflera arboricola petioles, Pittosporum crassifolium stems and Fagus sylvatica stems), v(h) was linearly correlated with sap velocity (v(s)) up to a v(s) of approximately 0.007 cm s(-1), equivalent to a flow of 1.8 g h(-1) through a 3-mm-diameter stem. Minimum detectable v(s) was approximately 0.0001 cm s(-1), equivalent to 0.025 g h(-1) through a 3-mm-diameter stem. Sensitivity increased with bark removal. Girdling had no effect on short-term measurements of in vivo sap flow, suggesting that phloem flows were too low to be separated from xylem flows. Fluctuating ambient temperatures increased variability in outdoor sap flow measurements. However, a consistent diurnal time-course of fruit pedicel sap flow was obtained, with flows towards 75-day-old kiwifruit lagging behind evaporative demand and peaking at 0.3 g h(-1) in the late afternoon.

Digital terrestrial photogrammetric methods for tree stem analysis

Treesearch

Neil A. Clark; Randolph H. Wynne; Daniel L. Schmoldt; Matt Winn

2000-01-01

A digital camera was used to measure diameters at various heights along the stem on 20 red oak trees. Diameter at breast height ranged from 16 to over 60 cm, and height to a 10-cm top ranged from 12 to 20 m. The chi-square maximum anticipated error of geometric mean diameter estimates at the 95 percent confidence level was within ±4 cm for all heights when...

Drought stress and tree size determine stem CO2 efflux in a tropical forest.

PubMed

Rowland, Lucy; da Costa, Antonio C L; Oliveira, Alex A R; Oliveira, Rafael S; Bittencourt, Paulo L; Costa, Patricia B; Giles, Andre L; Sosa, Azul I; Coughlin, Ingrid; Godlee, John L; Vasconcelos, Steel S; Junior, João A S; Ferreira, Leandro V; Mencuccini, Maurizio; Meir, Patrick

2018-06-01

CO 2 efflux from stems (CO 2_stem ) accounts for a substantial fraction of tropical forest gross primary productivity, but the climate sensitivity of this flux remains poorly understood. We present a study of tropical forest CO 2_stem from 215 trees across wet and dry seasons, at the world's longest running tropical forest drought experiment site. We show a 27% increase in wet season CO 2_stem in the droughted forest relative to a control forest. This was driven by increasing CO 2_stem in trees 10-40 cm diameter. Furthermore, we show that drought increases the proportion of maintenance to growth respiration in trees > 20 cm diameter, including large increases in maintenance respiration in the largest droughted trees, > 40 cm diameter. However, we found no clear taxonomic influence on CO 2_stem and were unable to accurately predict how drought sensitivity altered ecosystem scale CO 2_stem , due to substantial uncertainty introduced by contrasting methods previously employed to scale CO 2_stem fluxes. Our findings indicate that under future scenarios of elevated drought, increases in CO 2_stem may augment carbon losses, weakening or potentially reversing the tropical forest carbon sink. However, due to substantial uncertainties in scaling CO 2_stem fluxes, stand-scale future estimates of changes in stem CO 2 emissions remain highly uncertain. © 2018 The Authors New Phytologist © 2018 New Phytologist Trust.

An assessment of the utility of a non-metric digital camera for measuring standing trees

Treesearch

Neil Clark; Randolph H. Wynne; Daniel L. Schmoldt; Matthew F. Winn

2000-01-01

Images acquired with a commercially available digital camera were used to make measurements on 20 red oak (Quercus spp.) stems. The ranges of diameter at breast height (DBH) and height to a 10 cm upper-stem diameter were 16-66 cm and 12-20 m, respectively. Camera stations located 3, 6, 9, 12, and 15 m from the stem were studied to determine the best distance to be...

Morphological indicators of stock quality and field performance of red oak (Quercus rubra L.) seedling underplanted in a central Ontario shelterwood

Treesearch

Daniel C. Dey; William C. Parker

1997-01-01

Initial stem diameter of bareroot red oak planting stock was a better morphological indicator of future height and diameter growth in a shelterwood underplanting than were initial shoot length and number of first-order lateral roots. Stem diameter near the root collar provides an integrated measure of the growth potential of red oak planting stock because of its strong...

Wood and bark specific gravity of small-diameter, pine-site hardwood in the south

Treesearch

F.G. Manwiller

1979-01-01

Ten small-diameter trees from each of the 22 species (220 trees) were sampled from throughout the southern United States. Mean SG was determined for stem wood and bark and the whole stem, for branch wood and bark and whole branches (to a minimum diameter of 0.05 in.), and for tree wood and bark and the whole tree. Significant differences were determined a) among the...

7 CFR 51.2934 - Diameter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom...

7 CFR 51.2934 - Diameter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom...

7 CFR 51.2934 - Diameter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom...

Comparison of standing volume estimates using optical dendrometers

Treesearch

Neil A. Clark; Stanley J. Zarnoch; Alexander Clark; Gregory A. Reams

2001-01-01

This study compared height and diameter measurements and volume estimates on 20 hardwood and 20 softwood stems using traditional optical dendrometers, an experimental camera instrument, and mechanical calipers. Multiple comparison tests showed significant differences among the means for lower stem diameters when the camera was used. There were no significant...

Comparison of Standing Volume Estimates Using Optical Dendrometers

Treesearch

Neil A. Clark; Stanley J. Zarnoch; Alexander Clark; Gregory A. Reams

2001-01-01

This study compared height and diameter measurements and volume estimates on 20 hardwood and 20 softwood stems using traditional optical dendrometers, an experimental camera instrument, and mechanical calipers. Multiple comparison tests showed significant differences among the means for lower stem diameters when the camera was used. There were no significant...

Dynamics of shearing force and its correlations with chemical compositions and in vitro dry matter digestibility of stylo (Stylosanthes guianensis) stem.

PubMed

Zi, Xuejuan; Li, Mao; Zhou, Hanlin; Tang, Jun; Cai, Yimin

2017-12-01

The study explored the dynamics of shearing force and its correlation with chemical compositions and in vitro dry matter digestibility (IVDMD) of stylo. The shearing force, diameter, linear density, chemical composition, and IVDMD of different height stylo stem were investigated. Linear regression analysis was done to determine the relationships between the shearing force and cut height, diameter, chemical composition, or IVDMD. The results showed that shearing force of stylo stem increased with plant height increasing and the crude protein (CP) content and IVDMD decreased but fiber content increased over time, resulting in decreased forage value. In addition, tall stem had greater shearing force than short stem. Moreover, shearing force is positively correlated with stem diameter, linear density and fiber fraction, but negatively correlated with CP content and IVDMD. Overall, shearing force is an indicator more direct, easier and faster to measure than chemical composition and digestibility for evaluation of forage nutritive value related to animal performance. Therefore, it can be used to evaluate the nutritive value of stylo.

Distinguishing the Biomass Allocation Variance Resulting from Ontogenetic Drift or Acclimation to Soil Texture

PubMed Central

Xie, Jiangbo; Tang, Lisong; Wang, Zhongyuan; Xu, Guiqing; Li, Yan

2012-01-01

In resource-poor environments, adjustment in plant biomass allocation implies a complex interplay between environmental signals and plant development rather than a delay in plant development alone. To understand how environmental factors influence biomass allocation or the developing phenotype, it is necessary to distinguish the biomass allocations resulting from environmental gradients or ontogenetic drift. Here, we compared the development trajectories of cotton plants (Gossypium herbaceum L.), which were grown in two contrasting soil textures during a 60-d period. Those results distinguished the biomass allocation pattern resulting from ontogenetic drift and the response to soil texture. The soil texture significantly changed the biomass allocation to leaves and roots, but not to stems. Soil texture also significantly changed the development trajectories of leaf and root traits, but did not change the scaling relationship between basal stem diameter and plant height. Results of nested ANOVAs of consecutive plant-size categories in both soil textures showed that soil gradients explained an average of 63.64–70.49% of the variation of biomass allocation to leaves and roots. Ontogenetic drift explained 77.47% of the variation in biomass allocation to stems. The results suggested that the environmental factors governed the biomass allocation to roots and leaves, and ontogenetic drift governed the biomass allocation to stems. The results demonstrated that biomass allocation to metabolically active organs (e.g., roots and leaves) was mainly governed by environmental factors, and that biomass allocation to metabolically non-active organs (e.g., stems) was mainly governed by ontogenetic drift. We concluded that differentiating the causes of development trajectories of plant traits was important to the understanding of plant response to environmental gradients. PMID:22911802

Fitting and Calibrating a Multilevel Mixed-Effects Stem Taper Model for Maritime Pine in NW Spain

PubMed Central

Arias-Rodil, Manuel; Castedo-Dorado, Fernando; Cámara-Obregón, Asunción; Diéguez-Aranda, Ulises

2015-01-01

Stem taper data are usually hierarchical (several measurements per tree, and several trees per plot), making application of a multilevel mixed-effects modelling approach essential. However, correlation between trees in the same plot/stand has often been ignored in previous studies. Fitting and calibration of a variable-exponent stem taper function were conducted using data from 420 trees felled in even-aged maritime pine (Pinus pinaster Ait.) stands in NW Spain. In the fitting step, the tree level explained much more variability than the plot level, and therefore calibration at plot level was omitted. Several stem heights were evaluated for measurement of the additional diameter needed for calibration at tree level. Calibration with an additional diameter measured at between 40 and 60% of total tree height showed the greatest improvement in volume and diameter predictions. If additional diameter measurement is not available, the fixed-effects model fitted by the ordinary least squares technique should be used. Finally, we also evaluated how the expansion of parameters with random effects affects the stem taper prediction, as we consider this a key question when applying the mixed-effects modelling approach to taper equations. The results showed that correlation between random effects should be taken into account when assessing the influence of random effects in stem taper prediction. PMID:26630156

Gravitropism in Higher Plant Shoots 1

PubMed Central

Sliwinski, Julianne E.; Salisbury, Frank B.

1984-01-01

Cross and longitudinal sections were prepared for light microscopy from vertical control plants (Xanthium strumarium L. Chicago strain), free-bending horizontal stems, plants restrained 48 hours in a horizontal position, and plants restrained 48 hours and then released, bending immediately about 130°. Top cells of free-bending stems shrink or elongate little; bottom cells continue to elongate. In restrained stems, bottom cells elongate some and increase in diameter; top cells elongate about as much but decrease in diameter. Upon release, bottom cells elongate more and decrease in diameter, while top cells shorten and increase in diameter, accounting for the bend. During restraint, bottom cells take up water while tissue pressures increase; top cells fail to take up water although tissue pressures are decreasing. Settling of amyloplasts was observed in cells of the starch sheath. Removal of different amounts of stem (Xanthium; Lycopersicon esculentum Miller, cv Bonny Best; Ricinus communis L. cv Yolo Wonder) showed that perception of gravity occurs in the bending (elongation) zone, although bending of fourth and fifth internodes from the top was less than in uncut controls. Uniform application of 1% indoleacetic acid in lanolin to cut stem surfaces partially restored bending. Reversing the gradient in tension/compression in horizontal stems (top under compression, bottom under tension) did not affect gravitropic bending. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 PMID:16663939

Species composition and structure of regenerated and remnant forest patches within an urban landscape

Treesearch

Wayne C. Zipperer

2002-01-01

Regenerated and remnant forest patches were inventoried in Syracuse, New York, USA to determine differences in structure, species composition, human disturbances, and landscape context. Patches had similar mean stem diameter, total stem density, and total basal areas, but differed with respect to diameter distribution, disturbance regime, landscape context, and...

5. VIEW OF INCLINED OUTLET GATE WHEEL, STEM AND STEM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW OF INCLINED OUTLET GATE WHEEL, STEM AND STEM GUIDE, (12' DIAMETER HARDESTY MODEL 112 CIRCULAR GATE), LOOKING NORTHEAST - High Mountain Dams in Bonneville Unit, Island Lake Dam, Wasatch National Forest, Kamas, Summit County, UT

7. VIEW OF UPRIGHT OUTLET GATE, WHEEL STEM AND STEM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW OF UPRIGHT OUTLET GATE, WHEEL STEM AND STEM GUIDE (14' DIAMETER CIRCULAR CALCO CAST IRON SLIDE GATE), LOOKING SOUTHEAST - High Mountain Dams in Bonneville Unit, Fire Lake Dam, Wasatch National Forest, Kamas, Summit County, UT

Forest structure and carbon dynamics in Amazonian tropical rain forests.

PubMed

Vieira, Simone; de Camargo, Plinio Barbosa; Selhorst, Diogo; da Silva, Roseana; Hutyra, Lucy; Chambers, Jeffrey Q; Brown, I Foster; Higuchi, Niro; dos Santos, Joaquim; Wofsy, Steven C; Trumbore, Susan E; Martinelli, Luiz Antonio

2004-08-01

Living trees constitute one of the major stocks of carbon in tropical forests. A better understanding of variations in the dynamics and structure of tropical forests is necessary for predicting the potential for these ecosystems to lose or store carbon, and for understanding how they recover from disturbance. Amazonian tropical forests occur over a vast area that encompasses differences in topography, climate, and geologic substrate. We observed large differences in forest structure, biomass, and tree growth rates in permanent plots situated in the eastern (near Santarém, Pará), central (near Manaus, Amazonas) and southwestern (near Rio Branco, Acre) Amazon, which differed in dry season length, as well as other factors. Forests at the two sites experiencing longer dry seasons, near Rio Branco and Santarém, had lower stem frequencies (460 and 466 ha(-1) respectively), less biodiversity (Shannon-Wiener diversity index), and smaller aboveground C stocks (140.6 and 122.1 Mg C ha(-1)) than the Manaus site (626 trees ha(-1), 180.1 Mg C ha(-1)), which had less seasonal variation in rainfall. The forests experiencing longer dry seasons also stored a greater proportion of the total biomass in trees with >50 cm diameter (41-45 vs 30% in Manaus). Rates of annual addition of C to living trees calculated from monthly dendrometer band measurements were 1.9 (Manaus), 2.8 (Santarém), and 2.6 (Rio Branco) Mg C ha(-1) year(-1). At all sites, trees in the 10-30 cm diameter class accounted for the highest proportion of annual growth (38, 55 and 56% in Manaus, Rio Branco and Santarém, respectively). Growth showed marked seasonality, with largest stem diameter increment in the wet season and smallest in the dry season, though this may be confounded by seasonal variation in wood water content. Year-to-year variations in C allocated to stem growth ranged from nearly zero in Rio Branco, to 0.8 Mg C ha(-1) year(-1) in Manaus (40% of annual mean) and 0.9 Mg C ha(-1) year(-1) (33% of annual mean) in Santarém, though this variability showed no significant relation with precipitation among years. Initial estimates of the C balance of live wood including recruitment and mortality as well as growth suggests that live wood biomass is at near steady-state in Manaus, but accumulating at about 1.5 Mg C ha(-1) at the other two sites. The causes of C imbalance in living wood pools in Santarém and Rio Branco sites are unknown, but may be related to previous disturbance at these sites. Based on size distribution and growth rate differences in the three sites, we predict that trees in the Manaus forest have greater mean age (approximately 240 years) than those of the other two forests (approximately 140 years).

Stem hydraulic capacitance decreases with drought stress: implications for modelling tree hydraulics in the Mediterranean oak Quercus ilex.

PubMed

Salomón, Roberto L; Limousin, Jean-Marc; Ourcival, Jean-Marc; Rodríguez-Calcerrada, Jesús; Steppe, Kathy

2017-08-01

Hydraulic modelling is a primary tool to predict plant performance in future drier scenarios. However, as most tree models are validated under non-stress conditions, they may fail when water becomes limiting. To simulate tree hydraulic functioning under moist and dry conditions, the current version of a water flow and storage mechanistic model was further developed by implementing equations that describe variation in xylem hydraulic resistance (R X ) and stem hydraulic capacitance (C S ) with predawn water potential (Ψ PD ). The model was applied in a Mediterranean forest experiencing intense summer drought, where six Quercus ilex trees were instrumented to monitor stem diameter variations and sap flow, concurrently with measurements of predawn and midday leaf water potential. Best model performance was observed when C S was allowed to decrease with decreasing Ψ PD . Hydraulic capacitance decreased from 62 to 25 kg m -3  MPa -1 across the growing season. In parallel, tree transpiration decreased to a greater extent than the capacitive water release and the contribution of stored water to transpiration increased from 2.0 to 5.1%. Our results demonstrate the importance of stored water and seasonality in C S for tree hydraulic functioning, and they suggest that C S should be considered to predict the drought response of trees with models. © 2017 John Wiley & Sons Ltd.

Walnut Twig Beetle (Coleoptera: Curculionidae: Scolytinae) Colonization of Eastern Black Walnut Nursery Trees

PubMed Central

Klingeman, William E.; Mayfield, Albert; Myers, Scott; Taylor, Adam

2017-01-01

Thousand cankers disease, caused by the invasive bark beetle Pityophthorus juglandis Blackman and an associated fungal pathogen Geosmithia morbida M.Kolařík, E. Freeland, C. Utley, N. Tisserat, currently threatens the health of eastern black walnut (Juglans nigra L.) in North America. Both the beetle and pathogen have expanded beyond their native range via transport of infested walnut wood. Geosmithia morbida can develop in seedlings following inoculation, but the ability of P. juglandis to colonize young, small diameter trees has not been investigated. This study assessed the beetle’s colonization behavior on J. nigra nursery trees. Beetles were caged directly onto the stems of walnut seedlings from five nursery sources representing a range of basal stem diameter classes. Seedlings were also exposed to P. juglandis in a limited choice, field-based experiment comparing pheromone-baited and unbaited stems. When beetles were caged directly onto stems, they probed and attempted to colonize seedlings across the range of diameters and across sources tested, including stems as small as 0.5 cm in diameter. In the field experiment, beetles only attempted to colonize seedlings that were baited with a pheromone lure and appeared to prefer (though not statistically significant) the larger diameter trees. Despite several successful penetrations into the phloem, there was no evidence of successful progeny development within the young trees in either experiment. Further investigation is recommended to better elucidate the risk nursery stock poses as a pathway for thousand cankers disease causal organisms. PMID:28973569

7 CFR 51.1174 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1174 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

7 CFR 51.1174 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Oranges and Tangelos Definitions § 51.1174 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

Dynamic relationship between the VOC emissions from a Scots pine stem and the tree water relations

NASA Astrophysics Data System (ADS)

Vanhatalo, Anni; Chan, Tommy; Aalto, Juho; Kolari, Pasi; Rissanen, Kaisa; Hakola, Hannele; Hölttä, Teemu; Bäck, Jaana

2013-04-01

The stems of coniferous trees contain huge storages of oleoresin. The composition of oleoresin depends on e.g. tree species, age, provenance, health status, and environmental conditions. Oleoresin is under pressure in the extensive network of resin ducts in wood and needles. It flows out from a mechanically damaged site to protect the tree by sealing the wounded site. Once in contact with air, volatile parts of oleoresin evaporate, and the residual compounds harden to make a solid protective seal over damaged tissues. The hardening time of the resin depends on evaporation rate of the volatiles which in turn depends on temperature. The storage is also toxic to herbivores and attracts predators that restrict the herbivore damage. Despite abundant knowledge on emissions of volatile isoprenoids from foliage, very little is known about their emissions from woody plant parts. We set up an experiment to measure emissions of isoprene and monoterpenes as well as two oxygenated VOCs, methanol and acetone, from a Scots pine (Pinus sylvestris) stem and branches. The measurements were started in early April and continued until mid-June, 2012. Simultaneously, we measured the dynamics of whole stem and xylem diameter changes, stem sap flow rate and foliage transpiration rate. These measurements were used to estimate A) pressure changes inside the living stem tissue and the water conducting xylem, B) the refilling of stem water stores after winter dehydration (the ratio of sap flow at the stem base to water loss by foliage), and C) the increase in tree water transport capacity (the ratio of maximum daily sap flow rate to the diurnal variation in xylem pressure) during spring due to winter embolism refilling and/or the temperature dependent root water uptake capacity. The results show that already very early in spring, significant VOC emissions from pine stem can be detected, and that they exhibit a diurnal cycle similar to that of ambient temperature. During the highest emission period a sudden decrease in stem diameter was observed, which we hypothesize could either indicate a decrease in the pressure of living cells in connection with stem VOC emissions, or result mechanically from exudation of oleoresin from the stem. We also found that the stem water stores and xylem water transport capacity increased during periods of VOC emissions, which indicates xylem embolism refilling during times of VOC emissions. A qualitative difference was found between VOC emissions from pine stem and thick branches, the stem emissions containing more sesquiterpenes. Most of the tree biomass is in the lower part of the stem, and as stem tissues are lacking green photosynthesizing tissue the emissions are supposed to be related to damage. Our results show that emissions from tree stems are connected to the tree water relations and that they are important during the period when the foliage still is rather inactive.

Optimizing lodgepole pine submerchantable log thermomechanical pulp

Treesearch

Gary C. Myers

2004-01-01

To restore and maintain ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. These stems are considered nonusable or underutilized (good, economical uses need to be developed). As of now, the most logical use for the small-diameter resource is pulp. In this study,...

7 CFR 51.783 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Grapefruit Definitions § 51.783 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end. ...

7 CFR 51.712 - Diameter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Standards for Grades of Oranges (Texas and States Other Than Florida, California, and Arizona) Definitions § 51.712 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

7 CFR 51.712 - Diameter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Standards for Grades of Oranges (Texas and States Other Than Florida, California, and Arizona) Definitions § 51.712 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

7 CFR 51.783 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Grapefruit Definitions § 51.783 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end. ...

7 CFR 51.1836 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Tangerines Definitions § 51.1836 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end. ...

7 CFR 51.1836 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Florida Tangerines Definitions § 51.1836 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end. ...

7 CFR 51.712 - Diameter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Standards for Grades of Oranges (Texas and States Other Than Florida, California, and Arizona) Definitions § 51.712 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem...

Diversity in global gene expression and morphology across a watercress (Nasturtium officinale R. Br.) germplasm collection: first steps to breeding

PubMed Central

Payne, Adrienne C.; Clarkson, Graham J.J.; Rothwell, Steve; Taylor, Gail

2015-01-01

Watercress (Nasturtium officinale R. Br.) is a nutrient intense, leafy crop that is consumed raw or in soups across the globe, but for which, currently no genomic resources or breeding programme exists. Promising morphological, biochemical and functional genomic variation was identified for the first time in a newly established watercress germplasm collection, consisting of 48 watercress accessions sourced from contrasting global locations. Stem length, stem diameter and anti-oxidant (AO) potential varied across the accessions. This variation was used to identify three extreme contrasting accessions for further analysis. Variation in global gene expression was investigated using an Affymetrix Arabidopsis ATH1 microarray gene chip, using the commercial control (C), an accession selected for dwarf phenotype with a high AO potential (dwarfAO, called ‘Boldrewood’) and one with high AO potential alone. A set of transcripts significantly differentially expressed between these three accessions, were identified, including transcripts involved in the regulation of growth and development and those involved in secondary metabolism. In particular, when differential gene expression was compared between C and dwarfAO, the dwarfAO was characterised by increased expression of genes encoding glucosinolates, which are known precursors of phenethyl isothiocyanate, linked to the anti-carcinogenic effects well-documented in watercress. This study provides the first analysis of natural variation across the watercress genome and has identified important underpinning information for future breeding for enhanced anti-carcinogenic properties and morphology traits in this nutrient-intense crop. PMID:26504575

7 CFR 51.2656 - Diameter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry. ...

7 CFR 51.1016 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Persian (Tahiti) Limes Definitions § 51.1016 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end of the...

7 CFR 51.2656 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the...

7 CFR 51.2656 - Diameter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry. ...

7 CFR 51.2656 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the...

7 CFR 51.2656 - Diameter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry. ...

7 CFR 51.1016 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Persian (Tahiti) Limes Definitions § 51.1016 Diameter. Diameter means the greatest dimension measured at right angles to a line from stem to blossom end of the...

Hydraulic conductivity and embolism in the mangrove tree Laguncularia racemosa.

PubMed

Ewers, Frank W; Lopez-Portillo, Jórge; Angeles, Guillermo; Fisher, Jack B

2004-09-01

We measured xylem pressure potentials, soil osmotic potentials, hydraulic conductivity and percent loss of conductivity (PLC) due to embolism, and made microscopic observations of perfused dye in the white mangrove tree, Laguncularia racemosa (L.) Gaertn. f., (1) to determine its vulnerability to air embolism compared with published results for the highly salt-tolerant red mangrove tree, Rhizophora mangle L., and (2) to identify possible relationships between air embolism, permanent blockage of vessels and stem diameter. Laguncularia racemosa was more vulnerable to embolism than reported for R. mangle, with 50 PLC at -3.4 MPa. Narrow stems (5-mm diameter) had higher PLC than larger stems (8.4- or 14-mm diameter) of the same plants. Basic fuchsin dye indicated that up to 89% of the vessels, especially in the narrow stems, had permanent blockage that could not be reversed by high pressure perfusion. Air embolism could lead to permanent vessel blockage and eventual stem mortality. Such vulnerability to embolism may restrict the growth of L. racemosa and limit its distribution to less salty areas of mangrove communities.

16 CFR 1512.6 - Requirements for steering system.

Code of Federal Regulations, 2010 CFR

2010-01-01

... stem insertion mark. The handlebar stem shall contain a permanent ring or mark which clearly indicates the minimum insertion depth of the handlebar stem into the fork assembly. The insertion mark shall not affect the structural integrity of the stem and shall not be less than 21/2 times the stem diameter from...

16 CFR 1512.6 - Requirements for steering system.

Code of Federal Regulations, 2011 CFR

2011-01-01

... stem insertion mark. The handlebar stem shall contain a permanent ring or mark which clearly indicates the minimum insertion depth of the handlebar stem into the fork assembly. The insertion mark shall not affect the structural integrity of the stem and shall not be less than 21/2 times the stem diameter from...

Reconstructing the Origin of Helianthus deserticola: Survival and Selection on the Desert Floor

PubMed Central

Gross, Briana L.; Kane, Nolan C.; Lexer, Christian; Ludwig, Fulco; Rosenthal, David M.; Donovan, Lisa A.; Rieseberg, Loren H.

2008-01-01

The diploid hybrid species Helianthus deserticola inhabits the desert floor, an extreme environment relative to its parental species Helianthus annuus and Helianthus petiolaris. Adaptation to the desert floor may have occurred via selection acting on transgressive, or extreme, traits in early hybrids between the parental species. We explored this possibility through a field experiment in the hybrid species’ native habitat using H. deserticola, H. annuus, H. petiolaris, and two populations of early-generation (BC2) hybrids between the parental species, which served as proxies for the ancestral genotype of the ancient hybrid species. Character expression was evaluated for each genotypic class. Helianthus deserticola was negatively transgressive for stem diameter, leaf area, and flowering date, and the latter two traits are likely to be advantageous in a desert environment. The BC2 hybrids contained a range of variation that overlapped these transgressive trait means, and an analysis of phenotypic selection revealed that some of the selective pressures on leaf size and flowering date, but not stem diameter, would move the BC2 population toward the H. deserticola phenotype. Thus, H. deserticola may have originated from habitat-mediated directional selection acting on hybrids between H. annuus and H. petiolaris in a desert environment. PMID:15278840

7 CFR 51.1359 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Pears for Canning Definitions § 51.1359 Diameter. Diameter means the greatest dimension of the pear taken at right angles to a line running from the stem to...

7 CFR 51.1359 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Pears for Canning Definitions § 51.1359 Diameter. Diameter means the greatest dimension of the pear taken at right angles to a line running from the stem to...

Proximal femoral anatomy and collared stems in hip arthroplasty: is a single collar size sufficient?

PubMed

Bonin, Nicolas; Gedouin, Jean-Emmanuel; Pibarot, Vincent; Bejui-Hughues, Jacques; Bothorel, Hugo; Saffarini, Mo; Batailler, Cécile

2017-10-03

Even if the benefits of collars are unclear, they remain widely used, in several femoral stem designs. This study aimed to determine whether collar size should be proportional to hip dimensions and morphology. The hypothesis was that the collar should be larger for greater stem sizes and for varus femoral necks. Computed Tomography scans of 204 healthy hips were digitally analysed and manually templated to determine principle dimensions, appropriate stem size and model, as well as cortical distance at the femoral calcar (ideal collar size). Univariable analysis revealed that cortical distance was moderately correlated with mediolateral offset (r = 0.572; p < 0.0001) and stem model (r = 0.520; p < 0.0001). Cortical distance was weakly correlated with head diameter (r = 0.399; p < 0.0001), stem size (r = 0.200; p = 0.017), and patient gender (r = 0.361; p < 0.0001). Multivariable analysis confirmed that stem model (p < 0.0001) and head diameter (p = 0.0162) are directly correlated to cortical distance. We found that cortical distance along the femoral calcar is directly correlated with the model of the stem implanted ('standard' or 'varus') and with the head diameter. This cortical distance indicates optimal collar size, which would grant maximum calcar coverage without prosthetic overhang. Collar size should be proportional to the size of the operated hip, and should be larger for 'varus' stem models than for 'standard' stem models.

Prediction and error of baldcypress stem volume from stump diameter

Treesearch

Bernard R. Parresol

1998-01-01

The need to estimate the volume of removals occurs for many reasons, such as in trespass cases, severance tax reports, and post-harvest assessments. A logarithmic model is presented for prediction of baldcypress total stem cubic foot volume using stump diameter as the independent variable. Because the error of prediction is as important as the volume estimate, the...

Evaluation of moisture reduction in small diameter trees after crushing

Treesearch

Donald L. Sirois; Cynthia L. Rawlins; Bryce J. Stokes

1991-01-01

Past studies have suggested that processing small diameter whole trees like those foumd on rights-of-way (ROWs) would help reduce transportion costs and increase energy value by lowering stem moisture content. Small stems were crushed by a roller crusher/splitter test bench machine and allowed dry under field conditions in Alabama. Tests were conducted in winter and...

Complex compatible taper and volume estimation systems for red and loblolly pine

Treesearch

John C. Byrne; David D. Reed

1986-01-01

Five equation systems are described which can be used to estimate upper stem diameter, total individual tree cubic-foot volume, and merchantable cubic-foot volumes to any merchantability imit (expressed in terms of diameter or height), both inside and outside bark. The equations provide consistent results since they are mathematically related and are fit using stem...

Calibration of the STEMS diameter growth model using FIA data

Treesearch

Veronica C. Lessard

2000-01-01

The diameter growth model used in STEMS, the Stand and Tree Evaluation and Modeling System, was originally calibrated using data from permanent growth plots in Minnesota, Wisconsin, and Michigan. Because the model has been applied in predicting growth using Forest Inventory and Analysis (FIA) data, it was appropriate to refit the model to FIA data. The model was...

Bark factors for Douglas-fir.

Treesearch

Floyd. Johnson

1966-01-01

Recent emphasis on the measurement of upper stem tree diameters with optical dendrometers has directed attention to procedures for converting these outside-bark diameters to inside-bark diameters. One procedure that has been used requires an assumption that the ratio of diameter inside bark to diameter outside bark (henceforth called bark factor) remains the same up...

7 CFR 51.907 - Diameter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.907 Diameter. Diameter means the greatest dimension of the berry taken at right angles to a line running from the stem to the...

7 CFR 51.907 - Diameter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.907 Diameter. Diameter means the greatest dimension of the berry taken at right angles to a line running from the stem to the...

7 CFR 51.907 - Diameter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Standards for Grades of Table Grapes (European or Vinifera Type) 1 Definitions § 51.907 Diameter. Diameter means the greatest dimension of the berry taken at right angles to a line running from the stem to the...

Cambial activity related to tree size in a mature silver-fir plantation.

PubMed

Rathgeber, Cyrille B K; Rossi, Sergio; Bontemps, Jean-Daniel

2011-09-01

Our knowledge about the influences of environmental factors on tree growth is principally based on the study of dominant trees. However, tree social status may influence intra-annual dynamics of growth, leading to differential responses to environmental conditions. The aim was to determine whether within-stand differences in stem diameters of trees belonging to different crown classes resulted from variations in the length of the growing period or in the rate of cell production. Cambial activity was monitored weekly in 2006 for three crown classes in a 40-year-old silver-fir (Abies alba) plantation near Nancy (France). Timings, duration and rate of tracheid production were assessed from anatomical observations of the developing xylem. Cambial activity started earlier, stopped later and lasted longer in dominant trees than in intermediate and suppressed ones. The onset of cambial activity was estimated to have taken 3 weeks to spread to 90 % of the trees in the stand, while the cessation needed 6 weeks. Cambial activity was more intense in dominant trees than in intermediate and suppressed ones. It was estimated that about 75 % of tree-ring width variability was attributable to the rate of cell production and only 25 % to its duration. Moreover, growth duration was correlated to tree height, while growth rate was better correlated to crown area. These results show that, in a closed conifer forest, stem diameter variations resulted principally from differences in the rate of xylem cell production rather than in its duration. Tree size interacts with environmental factors to control the timings, duration and rate of cambial activity through functional processes involving source-sink relationships principally, but also hormonal controls.

7 CFR 51.907 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Definitions § 51.907 Diameter. Diameter means the greatest dimension of the berry taken at right angles to a line running from the stem to the blossom end. [36 FR 9126, May 20, 1971. Redesignated at 42 FR 32514...

7 CFR 51.907 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Definitions § 51.907 Diameter. Diameter means the greatest dimension of the berry taken at right angles to a line running from the stem to the blossom end. [36 FR 9126, May 20, 1971. Redesignated at 42 FR 32514...

Aspen height, stem-girth and survivorship in an area of high ungulate use

USGS Publications Warehouse

Keigley, R.B.; Frisina, M.R.

2008-01-01

An increase in ungulate population size potentially exposes aspen suckers, saplings, and trees to increased use. This study examined how stem height and girth influenced the selection of stems by ungulates for browsing, rubbing, and gnawing, and reconstructed the history of ungulate use for the study area. Transects were run through each of three aspen clones growing in southwestern Montana to determine height, circumference, and the surface area from which bark was totally and partially removed by rubbing and gnawing. Stems 20-250 cm tall were browsed. Stems 2-13 cm diameter were preferentially selected for rubbing and gnawing. The area of totally removed bark on dead saplings was twice the area of removed bark on live stems of similar diameter, suggesting that bark removal played a major role in the death of some stems. Based on an analysis of stem height and age, ungulate browsing was inferred to have increased from a light-to-moderate level to an intense level in 1991. The depth of scars was used to date scarring events. An increase in rubbing and gnawing was determined to have occurred about 1985. We concluded that elk were primarily responsible for the observed impacts. The combined effect of rubbing, gnawing, and browsing affects a broader span of ages compared to the effect of browsing alone. If prescribed fire is used to rejuvenate aspen stands, the resulting young stems should be protected from heavy browsing, rubbing and gnawing until they reach about 13 cm diameter and have grown out of the browse zone.

Whole-tree harvesting of pines with taproot attached

Treesearch

P. Koch

1974-01-01

The taproot of a 15- to 3O-yearold slash pine, with lateral roots pruned away, weighs about 20% as much as the bark-free merchantable stem to a four-inch top (dry-weight basis). Maximum taproot diameter, a few inches below ground level, is 1.5 to two times stem diameter at breast height. Length in sandy loam soils is commonly three to five feet.

Evaluation of the Barr & Stroud FP15 and Criterion 400 laser dendrometers for measuring upper stem diameters and heights

Treesearch

Michael S. Williams; Kenneth L. Cormier; Ronald G. Briggs; Donald L. Martinez

1999-01-01

Calibrated Barr & Stroud FP15 and Criterion 400 laser dendrometers were tested for reliability in measuring upper stem diameters and heights under typical field conditions. Data were collected in the Black Hills National Forest, which covers parts of South Dakota and Wyoming in the United States. Mixed effects models were employed to account for differences between...

Comparing the STEMS and AFIS growth models with respect to the uncertainty of predictions

Treesearch

Ronald E. McRoberts; Margaret R. Holdaway; Veronica C. Lessard

2000-01-01

The uncertainty in 5-, 10-, and 20-year diameter growth predictions is estimated using Monte Carlo simulations for four Lake States tree species. Two sets of diameter growth models are used: recalibrations of the STEMS models using forest inventory and analysis data, and new growth models developed as a component of an annual forest inventory system for the North...

Estimating Pinus palustris tree diameter and stem volume from tree height, crown area and stand-level parameters

Treesearch

C.A. Gonzalez-Benecke; Salvador A. Gezan; Lisa J. Samuelson; Wendell P. Cropper; Daniel J. Leduc; Timothy A. Martin

2014-01-01

Accurate and efficient estimation of forest growth and live biomass is a critical element in assessing potential responses to forest management and environmental change. The objective of this study was to develop models to predict longleaf pine tree diameter at breast height (dbh) and merchantable stem volume (V) using data obtained from field measurements. We used...

D.b.h./crown diameter relationships in mixed Appalachian hardwood stands

Treesearch

Neil I. Lamson; Neil I. Lamson

1987-01-01

Linear regression formulae for predicting crown diameter as a function of stem diameter are presented for nine species found in 50- to 80-year-old mixed hardwood stands in north-central West Virginia. Generally, crown diameter was closely related to tolerance; more tolerant species had larger crowns.

A biophysical model of kiwifruit (Actinidia deliciosa) berry development

PubMed Central

Hall, Alistair J.

2013-01-01

A model of kiwifruit berry development is presented, building on the model of Fishman and Génard used for peach fruit. That model has been extended to incorporate a number of important features of kiwifruit growth. First, the kiwifruit berry is attached to the stem through a pedicel/receptacle complex which contributes significantly to the hydraulic resistance between the stem and the fruit, and this resistance changes considerably during the season. Second, much of the carbohydrate in kiwifruit berries is stored as starch until the fruit matures late in the season, when the starch hydrolyses to soluble sugars. This starch storage has a major effect on the osmotic potential of the fruit, so an existing model of kiwifruit starch dynamics was included in the model. Using previously published approaches, we also included elasticity and extended the modelling period to cover both the cell division and cell expansion phases of growth. The resulting model showed close simulation of field observations of fresh weight, dry matter, starch, and soluble solids in kiwifruit. Comparison with continuous measurements of fruit diameter confirmed that elasticity was needed to adequately simulate observed diurnal variation in fruit size. Sensitivity analyses suggested that the model is particularly sensitive to variation in inputs relating to water (stem water potential and the humidity of the air), and to parameters controlling cell expansion (cell wall extensibility). Some limitations in the model structure were identified, suggesting that a revised model including current apoplastic/symplastic concepts needs to be developed. PMID:24123250

A biophysical model of kiwifruit (Actinidia deliciosa) berry development.

PubMed

Hall, Alistair J; Minchin, Peter E H; Clearwater, Michael J; Génard, Michel

2013-12-01

A model of kiwifruit berry development is presented, building on the model of Fishman and Génard used for peach fruit. That model has been extended to incorporate a number of important features of kiwifruit growth. First, the kiwifruit berry is attached to the stem through a pedicel/receptacle complex which contributes significantly to the hydraulic resistance between the stem and the fruit, and this resistance changes considerably during the season. Second, much of the carbohydrate in kiwifruit berries is stored as starch until the fruit matures late in the season, when the starch hydrolyses to soluble sugars. This starch storage has a major effect on the osmotic potential of the fruit, so an existing model of kiwifruit starch dynamics was included in the model. Using previously published approaches, we also included elasticity and extended the modelling period to cover both the cell division and cell expansion phases of growth. The resulting model showed close simulation of field observations of fresh weight, dry matter, starch, and soluble solids in kiwifruit. Comparison with continuous measurements of fruit diameter confirmed that elasticity was needed to adequately simulate observed diurnal variation in fruit size. Sensitivity analyses suggested that the model is particularly sensitive to variation in inputs relating to water (stem water potential and the humidity of the air), and to parameters controlling cell expansion (cell wall extensibility). Some limitations in the model structure were identified, suggesting that a revised model including current apoplastic/symplastic concepts needs to be developed.

NaCl - Changes stem morphology, anatomy and phloem structure in Lucerne (Medicago sativa cv. Gabès): Comparison of upper and lower internodes.

PubMed

Nja, Riheb Ben; Merceron, Bruno; Faucher, Mireille; Fleurat-Lessard, Pierrette; Béré, Emile

2018-02-01

In M. sativa cv. Gabès plants treated with 150mM NaCl, the height of the stem is decreased and the internode number, length and diameter are reduced. This depressive effect on growth, but also on photosynthetic activity and water balance, is accompanied by structural changes. In the upper internodes, NaCl treatment increases cambium development, so that the vascular ring is initiated earlier than in controls. In the lower internodes, the number of lignified phloem fibers is increased by NaCl, and their wall thickness is augmented, compared to controls; in the phloem complex, the nacreous layer is enlarged, the number of internal wall ingrowths is increased, but companion cells are damaged. In the treated lower internodes, few vessels occur in the secondary xylem, which is by contrast rich in lignified fibers and in wide vessels grouped in the metaxylem area; protoxylem parenchyma and adjacent pith are also lignified. In addition, in treated lower internodes, starch grains are less abundant than in controls, and this variation might be related to the decrease of photosynthesis. When taken together, qualitative and quantitative results indicate that the saline stress has a marked morpho-anatomical impact on the M. sativa Gabès stem. In particular, variations of secondary derivative distribution, increased wall thickening, lignification of phloem and xylem fibers and damage in the phloem complex are NaCl-induced responses, and are more expressed in the lower than in the upper internodes. The reinforcement of the stem lignified vasculature is thus a positive response to stress, but it has a negative impact on the quality of the forage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stemness of spermatogonial stem cells encapsulated in alginate hydrogel during cryopreservation.

PubMed

Pirnia, A; Parivar, K; Hemadi, M; Yaghmaei, P; Gholami, M

2017-06-01

This study investigated the effect of spermatogonial stem cell encapsulated in alginate hydrogel during cryopreservation, as cells were protected against damage during cryopreservation within the hydrogel. Spermatogonial stem cells were isolated from the testes of Balb/c mice pups (6 days old), purified in laminin-coated dishes and CD90.1 microbeads, encapsulated in alginate hydrogel and then cryopreserved. After thawing, cell viability and Spermatogonial stem cell (SSC) colony diameter were evaluated. After RNA was isolated and cDNA was synthesised, the expression of stemness genes was considered using RT real-time PCR. Finally, spermatogonial stem cells labelled with BrdU were transplanted to busulfan azoospermic mouse models. Lin28a and Sall4 genes were significantly upregulated after cryopreservation in alginate hydrogel. However, cell viability was significantly decreased. The diameter of colonies consisting of spermatogonial stem cells freeze-thawed in alginate microbeads showed no significant difference with fresh spermatogonial stem cells and the control group. The injection of freeze-thawed spermatogonial stem cells encapsulated in alginate hydrogel resulted in spermatogenesis recovery. Alginate mimics the extracellular matrices (ECM) for spermatogonial stem cells; therefore, it can support stemness potential during the cell cryopreservation process and restart spermatogenesis after transplantation. © 2016 Blackwell Verlag GmbH.

30 CFR 75.1322 - Stemming boreholes

Code of Federal Regulations, 2010 CFR

2010-07-01

... water stemming bags shall be tamped to fill the entire cross sectional area of the borehole. (c... water stemming bag shall be within 1/4 of an inch of the diameter of the drill bit used to drill the borehole. (h) Water stemming bags shall be constructed of tear-resistant and flame-resistant material and...

7 CFR 52.3761 - Defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

... to the degree of freedom from harmless extraneous vegetable material, stems, and portions thereof... the stem-flower axis. A defect is a unit where the angle of these two axes exceeds 45 degrees. (5... pitted olive equal to or exceeding the area of a circle 5 mm in diameter. (12) Stem means a stem that...

7 CFR 52.3761 - Defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

... to the degree of freedom from harmless extraneous vegetable material, stems, and portions thereof... the stem-flower axis. A defect is a unit where the angle of these two axes exceeds 45 degrees. (5... pitted olive equal to or exceeding the area of a circle 5 mm in diameter. (12) Stem means a stem that...

Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts

NASA Astrophysics Data System (ADS)

Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

2016-01-01

We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices. Electronic supplementary information (ESI) available: Comparison between the Co monometallic catalyst system and the Co/Mo bimetallic catalyst system, the effect of CVD temperature on the G/D ratio, the effect of ethanol partial pressure on the morphology, diameter and quality of SWNT films, and Raman spectra of the Si/SiO2 substrate. See DOI: 10.1039/c5nr06007a

Retransformation bias in a stem profile model

Treesearch

Raymond L. Czaplewski; David Bruce

1990-01-01

An unbiased profile model, fit to diameter divided by diameter at breast height, overestimated volume of 5.3-m log sections by 0.5 to 3.5%. Another unbiased profile model, fit to squared diameter divided by squared diameter at breast height, underestimated bole diameters by 0.2 to 2.1%. These biases are caused by retransformation of the predicted dependent variable;...

Temperature variation and distribution of living cells within tree stems: implications for stem respiration modeling and scale-up.

PubMed

Stockfors, J

2000-09-01

Few studies have examined variation in respiration rates within trees, and even fewer studies have focused on variation caused by within-stem temperature differences. In this study, stem temperatures at 40 positions in the stem of one 30-year-old Norway spruce (Picea abies (L.) Karst.) were measured during 40 days between July 1994 and June 1995. The temperature data were used to simulate variations in respiration rate within the stem. The simulations assumed that the temperature-respiration relationship was constant (Q10 = 2) for all days and all stem positions. Total respiration for the whole stem was calculated by interpolating the temperature between the thermocouples and integrating the respiration rates in three dimensions. Total respiration rate of the stem was then compared to respiration rate scaled up from horizontal planes at the thermocouple heights (40, 140, 240 and 340 cm) on a surface area and on a sapwood volume basis. Simulations were made for three distributions of living cells in the stems: one with a constant 5% fraction of living cells, disregarding depth into the stem; one with a living cell fraction decreasing linearly with depth into the stem; and one with an exponentially decreasing fraction of living cells. Mean temperature variation within the stem was 3.7 degrees C, and was more than 10 degrees C for 8% of the time. The maximum measured temperature difference was 21.5 degrees C. The corresponding mean variation in respiration was 35% and was more than 50% for 24% of the time. Scaling up respiration rates from different heights between 40 and 240 cm to the whole stem produced an error of 2 to 58% for the whole year. For a single sunny day, the error was between 2 and 72%. Thus, within-stem variations in temperature may significantly affect the accuracy of scaling respiration data obtained from small samples to whole trees. A careful choice of chamber position and basis for scaling is necessary to minimize errors from variation in temperature.

Relationships of inside and outside bark diameters for young growth mixed-conifer species in the Sierra Nevada

Treesearch

K. Leroy Dolph

1984-01-01

The linear relationship of inside to outside bark diameter at breast height provides a basis for estimating diameter inside bark from diameter outside bark. Estimates of diameter inside bark and past diameter outside bark are useful in predicting growth and yield. During field seasons 1979-1982, data were obtained from stem analysis of 931 trees in young-growth stands...

A rapid decrease in temperature induces latewood formation in artificially reactivated cambium of conifer stems

PubMed Central

Begum, Shahanara; Nakaba, Satoshi; Yamagishi, Yusuke; Yamane, Kenichi; Islam, Md. Azharul; Oribe, Yuichiro; Ko, Jae-Heung; Jin, Hyun-O; Funada, Ryo

2012-01-01

Background and Aims Latewood formation in conifers occurs during the later part of the growing season, when the cell division activity of the cambium declines. Changes in temperature might be important for wood formation in trees. Therefore, the effects of a rapid decrease in temperature on cellular morphology of tracheids were investigated in localized heating-induced cambial reactivation in Cryptomeria japonica trees and in Abies firma seedlings. Methods Electric heating tape and heating ribbon were wrapped on the stems of C. japonica trees and A. firma seedlings. Heating was discontinued when 11 or 12 and eight or nine radial files of differentiating and differentiated tracheids had been produced in C. japonica and A. firma stems, respectively. Tracheid diameter, cell wall thickness, percentage of cell wall area and percentage of lumen area were determined by image analysis of transverse sections and scanning electron microscopy. Key Results Localized heating induced earlier cambial reactivation and xylem differentiation in stems of C. japonica and A. firma as compared with non-heated stems. One week after cessation of heating, there were no obvious changes in the dimensions of the differentiating tracheids in the samples from adult C. japonica. In contrast, tracheids with a smaller diameter were observed in A. firma seedlings after 1 week of cessation of heating. Two or three weeks after cessation of heating, tracheids with reduced diameters and thickened cell walls were found. The results showed that the rapid decrease in temperature produced slender tracheids with obvious thickening of cell walls that resembled latewood cells. Conclusions The results suggest that a localized decrease in temperature of stems induces changes in the diameter and cell wall thickness of differentiating tracheids, indicating that cambium and its derivatives can respond directly to changes in temperature. PMID:22843340

Stem demography and postfire recruitment of a resprouting serotinous conifer

USGS Publications Warehouse

Keeley, Jon E.; Keeley, Melanie B.; Bond, William J.

1999-01-01

The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4–9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionallyWiddring-tonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fires, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in theCupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait inWiddringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,’but also are intense enough to incinerate cone-bearing stems.

Stem demography and post-fire recruitment of a resprouting serotinous conifer

USGS Publications Warehouse

Keeley, J.E.; Keeley, M.B.; Bond, W.J.

1999-01-01

The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4 - 9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionally Widdringtonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fries, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in the Cupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait in Widdringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,' but also are intense enough to incinerate cone-bearing stems.

Variations in diameter measurements of Robusta Eucalyptus due to swelling and shrinking of bark

Treesearch

Robert E. Burgan

1971-01-01

Trunk diameters of Eucalyptus robusta trees shrink and swell as bark moisture content changes. Diameter variations from this cause as measured on six trees with a dial-gage dendrometer were less than 1 percent of trunk diameter. To compare this variation with the variation in d.b.h. measurements that can result from personal techiques of using a...

TH-CD-BRA-12: Impact of a Magnetic Field On the Response From a Plastic Scintillation Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Therriault-Proulx, F; Wen, Z; Ibbott, G

Purpose: To study the effect of a strong magnetic field on the scintillation and the stem effect from a plastic scintillation detector (PSD) and evaluate its accuracy to measure dose. Methods: A plastic scintillation detector and a bare plastic fiber were placed inside a magnet of adjustable field strength (B=0−1.5T) and irradiated by a 6-MV photon beam (Elekta Versa HD LINAC). The PSD was built in-house using a scintillating fiber (BCF-60, 3-mm long × 1-mm diameter) coupled to an optical fiber similar to the bare fiber (PMMA, 12-m long, 1-mm diameter). Light output spectra were acquired with a spectrometer. Intensitymore » and shape of the output spectra were compared as a function of the magnetic field strength. The bare fiber was used to study the behavior of the stem effect (composed of Cerenkov and fluorescence). The spectrometry setup allowed to perform a previously demonstrated hyperspectral stem-effect removal and calculated dose was studied as a function of the magnetic field strength. Results: Signal intensities were shown to increase with the magnetic field strength by up to 19% and 79% at 1.5T in comparison to the irradiation without a magnetic field, for respectively the PSD and the bare fiber. The light produced by Cerenkov effect in the optical fiber was shown to be the major component affected by the magnetic field. Effect of the magnetic field on the electrons trajectory may explain this behavior. Finally, accounting for the stem effect using the hyperspectral approach led to accuracy in dose measurement within 2.6%. Interestingly, variations in accuracy were negligible for values over 0.3T. Conclusion: Dependence of PSDs to magnetic field is mainly due to the Cerenkov light. When accounting for it, PSDs become a candidate of choice for both quality assurance and in vivo dosimetry of therapy under strong magnetic fields (e.g. for MRI-Linacs).« less

Seed production estimation for mountain big sagebrush (Artemisia tridentata ssp. vaseyana)

Treesearch

Melissa L. Landeen; Loreen Allphin; Stanley G. Kitchen; Steven L. Petersen

2017-01-01

Seed production is an essential component of postdisturbance recovery for mountain big sagebrush (Artemisia tridentata Nutt. ssp vaseyana [Rydb] Beetle; MBS). We tested a method for rapid estimation of MBS seed production using measurements of inflorescence morphology. We measured total stem length, stem length from first branchlet to stem tip, stem diameter, fresh...

Electron-beam broadening in amorphous carbon films in low-energy scanning transmission electron microscopy.

PubMed

Drees, H; Müller, E; Dries, M; Gerthsen, D

2018-02-01

Resolution in scanning transmission electron microscopy (STEM) is ultimately limited by the diameter of the electron beam. The electron beam diameter is not only determined by the properties of the condenser lens system but also by electron scattering in the specimen which leads to electron-beam broadening and degradation of the resolution with increasing specimen thickness. In this work we introduce a new method to measure electron-beam broadening which is based on STEM imaging with a multi-segmented STEM detector. We focus on STEM at low electron energies between 10 and 30 keV and use an amorphous carbon film with known thickness as test object. The experimental results are compared with calculated beam diameters using different analytical models and Monte-Carlo simulations. We find excellent agreement of the experimental data with the recently published model by Gauvin and Rudinsky [1] for small t/λ el (thickness to elastic mean free path) values which are considered in our study. Copyright © 2017 Elsevier B.V. All rights reserved.

[Effects of forest gap size on the growth and form quality of Taxus wallichina var. mairei in Cunninghamia lanceolata forests].

PubMed

Ou, Jian de; Wu, Zhi Zhuang; Luo, Ning

2016-10-01

In order to clarify the effects of forest gap size on the growth and stem form quality of Taxus wallichina var. mairei and effectiveness of the precious timbers cultivation, 25 sample plots in Cunninghamia lanceolata forest gaps were established in Mingxi County, Fujian Province, China to determine the indices of the growth, stem form and branching indices of T. wallichina var. mairei seedlings. The relationships between the gap size and growth, stem form and branching were investigated. The 25 sample plots were located at five microhabitats which were classified based on gap size as follows: Class1, 2, 3, 4 and 5, which had a gap size of 25-50 m 2 , 50-75 m 2 , 75-100 m 2 , 100-125 m 2 and 125-150 m 2 , respectively. The evaluation index system of precious timbers was built by using hierarchical analysis. The 5 classes of forest gaps were evaluated comprehensively by using the multiobjective decision making method. The results showed that gap size significantly affected 11 indices, i.e., height, DBH, crown width, forking rate, stem straightness, stem fullness, taperingness, diameter height ratio, height under living branch, interval between branches, and max-branch base diameter. Class1and 2 both significantly promoted the growth of height, DBH and crown width, and both significantly inhibited forking rate and taperingness, and improved stem straightness. Class2 significantly improved stem fullness and diameter height ratio. Class1and 2 significantly improved height under living branch and reduced max-branch base diameter. Class 1 significantly increased interval between branches. Class1and2 significantly improved the comprehensive evaluation score of precious timbers. This study suggested that controlled cutting intensity could be used to create forest gaps of 25-75 m 2 , which improved the precious timber cultivating process of T. wallichina var. mairei in C. lanceolata forests.

Thread gauge for measuring thread pitch diameters

DOEpatents

Brewster, A.L.

1985-11-19

A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts is disclosed. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade. 2 figs.

Thread gauge for measuring thread pitch diameters

DOEpatents

Brewster, Albert L.

1985-01-01

A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade.

Consistent, small effects of treefall disturbances on the composition and diversity of four Amazonian forests.

PubMed

Baker, Timothy R; Vela Díaz, Dilys M; Chama Moscoso, Victor; Navarro, Gilberto; Monteagudo, Abel; Pinto, Ruy; Cangani, Katia; Fyllas, Nikolaos M; Lopez Gonzalez, Gabriela; Laurance, William F; Lewis, Simon L; Lloyd, Jonathan; Ter Steege, Hans; Terborgh, John W; Phillips, Oliver L

2016-03-01

Understanding the resilience of moist tropical forests to treefall disturbance events is important for understanding the mechanisms that underlie species coexistence and for predicting the future composition of these ecosystems. Here, we test whether variation in the functional composition of Amazonian forests determines their resilience to disturbance.We studied the legacy of natural treefall disturbance events in four forests across Amazonia that differ substantially in functional composition. We compared the composition and diversity of all free-standing woody stems 2-10 cm diameter in previously disturbed and undisturbed 20 × 20 m subplots within 55, one-hectare, long-term forest inventory plots.Overall, stem number increased following disturbance, and species and functional composition shifted to favour light-wooded, small-seeded taxa. Alpha-diversity increased, but beta-diversity was unaffected by disturbance, in all four forests.Changes in response to disturbance in both functional composition and alpha-diversity were, however, small (2 - 4% depending on the parameter) and similar among forests. Synthesis . This study demonstrates that variation in the functional composition of Amazonian forests does not lead to large differences in the response of these forests to treefall disturbances, and overall, these events have a minor role in maintaining the diversity of these ecosystems.

Stability analysis of a high fibre yield and low lignin content "thick stem" mutant in tossa jute (Corchorus olitorius L.).

PubMed

Mandal, Aninda; Datta, Animesh K

2014-01-01

A "thick stem" mutant of Corchorus olitorius L. was induced at M2 (0.50%, 4 h, EMS) and the true breeding mutant is assessed across generations (M5 to M7) considering morphometric traits as well as SEM analysis of pollen grains and raw jute fibres, stem anatomy, cytogenetical attributes, and lignin content in relation to control. Furthermore, single fibre diameter and tensile strength are also analysed. The objective is to assess the stability of mutant for its effective exploration for raising a new plant type in tossa jute for commercial exploitation and efficient breeding. The mutant trait is monogenic recessive to normal. Results indicate that "thick stem" mutant is stable across generations (2n = 14) with distinctive high seed and fibre yield and significantly low lignin content. Stem anatomy of the mutant shows significant enhancement in fibre zone, number of fibre pyramids and fibre bundles per pyramid, and diameter of fibre cell in relation to control. Moreover, tensile strength of mutant fibre is significantly higher than control fibre and the trait is inversely related to fibre diameter. However the mutant is associated with low germination frequency, poor seed viability, and high pollen sterility, which may be eliminated through mutational approach followed by rigorous selection and efficient breeding.

Synthesis of subnanometer-diameter vertically aligned single-walled carbon nanotubes with copper-anchored cobalt catalysts.

PubMed

Cui, Kehang; Kumamoto, Akihito; Xiang, Rong; An, Hua; Wang, Benjamin; Inoue, Taiki; Chiashi, Shohei; Ikuhara, Yuichi; Maruyama, Shigeo

2016-01-21

We synthesize vertically aligned single-walled carbon nanotubes (VA-SWNTs) with subnanometer diameters on quartz (and SiO2/Si) substrates by alcohol CVD using Cu-anchored Co catalysts. The uniform VA-SWNTs with a nanotube diameter of 1 nm are synthesized at a CVD temperature of 800 °C and have a thickness of several tens of μm. The diameter of SWNTs was reduced to 0.75 nm at 650 °C with the G/D ratio maintained above 24. Scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (EDS-STEM) and high angle annular dark field (HAADF-STEM) imaging of the Co/Cu bimetallic catalyst system showed that Co catalysts were captured and anchored by adjacent Cu nanoparticles, and thus were prevented from coalescing into a larger size, which contributed to the small diameter of SWNTs. The correlation between the catalyst size and the SWNT diameter was experimentally clarified. The subnanometer-diameter and high-quality SWNTs are expected to pave the way to replace silicon for next-generation optoelectronic and photovoltaic devices.

Prediction and measurement of thermally induced cambial tissue necrosis in tree stems

Treesearch

Joshua L. Jones; Brent W. Webb; Bret W. Butler; Matthew B. Dickinson; Daniel Jimenez; James Reardon; Anthony S. Bova

2006-01-01

A model for fire-induced heating in tree stems is linked to a recently reported model for tissue necrosis. The combined model produces cambial tissue necrosis predictions in a tree stem as a function of heating rate, heating time, tree species, and stem diameter. Model accuracy is evaluated by comparison with experimental measurements in two hardwood and two softwood...

Development of volume equations using data obtained by upper stem dendrometry with Monte Carlo integration: preliminary results for eastern redcedar

Treesearch

Thomas B. Lynch; Rodney E. Will; Rider Reynolds

2013-01-01

Preliminary results are given for development of an eastern redcedar (Juniperus virginiana) cubic-volume equation based on measurements of redcedar sample tree stem volume using dendrometry with Monte Carlo integration. Monte Carlo integration techniques can be used to provide unbiased estimates of stem cubic-foot volume based on upper stem diameter...

Effect of the nanowire diameter on the linearity of the response of GaN-based heterostructured nanowire photodetectors.

PubMed

Spies, Maria; Polaczyński, Jakub; Ajay, Akhil; Kalita, Dipankar; Luong, Minh Anh; Lähnemann, Jonas; Gayral, Bruno; den Hertog, Martien I; Monroy, Eva

2018-06-22

Nanowire photodetectors are investigated because of their compatibility with flexible electronics, or for the implementation of on-chip optical interconnects. Such devices are characterized by ultrahigh photocurrent gain, but their photoresponse scales sublinearly with the optical power. Here, we present a study of single-nanowire photodetectors displaying a linear response to ultraviolet illumination. Their structure consists of a GaN nanowire incorporating an AlN/GaN/AlN heterostructure, which generates an internal electric field. The activity of the heterostructure is confirmed by the rectifying behavior of the current-voltage characteristics in the dark, as well as by the asymmetry of the photoresponse in magnitude and linearity. Under reverse bias (negative bias on the GaN cap segment), the detectors behave linearly with the impinging optical power when the nanowire diameter is below a certain threshold (≈80 nm), which corresponds to the total depletion of the nanowire stem due to the Fermi level pinning at the sidewalls. In the case of nanowires that are only partially depleted, their nonlinearity is explained by a nonlinear variation of the diameter of their central conducting channel under illumination.

Effect of the nanowire diameter on the linearity of the response of GaN-based heterostructured nanowire photodetectors

NASA Astrophysics Data System (ADS)

Spies, Maria; Polaczyński, Jakub; Ajay, Akhil; Kalita, Dipankar; Luong, Minh Anh; Lähnemann, Jonas; Gayral, Bruno; den Hertog, Martien I.; Monroy, Eva

2018-06-01

Nanowire photodetectors are investigated because of their compatibility with flexible electronics, or for the implementation of on-chip optical interconnects. Such devices are characterized by ultrahigh photocurrent gain, but their photoresponse scales sublinearly with the optical power. Here, we present a study of single-nanowire photodetectors displaying a linear response to ultraviolet illumination. Their structure consists of a GaN nanowire incorporating an AlN/GaN/AlN heterostructure, which generates an internal electric field. The activity of the heterostructure is confirmed by the rectifying behavior of the current–voltage characteristics in the dark, as well as by the asymmetry of the photoresponse in magnitude and linearity. Under reverse bias (negative bias on the GaN cap segment), the detectors behave linearly with the impinging optical power when the nanowire diameter is below a certain threshold (≈80 nm), which corresponds to the total depletion of the nanowire stem due to the Fermi level pinning at the sidewalls. In the case of nanowires that are only partially depleted, their nonlinearity is explained by a nonlinear variation of the diameter of their central conducting channel under illumination.

Nonlinear equations for predictiing diameter inside bark at breast height for young-growth red fir in California and southern Oregon

Treesearch

K. Leroy Dolph

1989-01-01

Inside bark diameters of young-growth red fir can be estimated from the relationship of inside bark diameter 10 outside bark diameter at breast height. Inside and outside bark diameter were obtained from stem analyses of 562 trees distributed across 56 sampling locations in the true fir forest type of California and southern Oregon. The resulting equation can predict...

Localized cooling of stems induces latewood formation and cambial dormancy during seasons of active cambium in conifers

PubMed Central

Begum, Shahanara; Kudo, Kayo; Matsuoka, Yugo; Nakaba, Satoshi; Yamagishi, Yusuke; Nabeshima, Eri; Rahman, Md Hasnat; Nugroho, Widyanto Dwi; Oribe, Yuichiro; Jin, Hyun-O; Funada, Ryo

2016-01-01

Background and Aims In temperate regions, trees undergo annual cycles of cambial growth, with periods of cambial activity and dormancy. Environmental factors might regulate the cambial growth, as well as the development of cambial derivatives. We investigated the effects of low temperature by localized cooling on cambial activity and latewood formation in two conifers, Chamaecyparis obtusa and Cryptomeria japonica. Methods A plastic rubber tube that contained cooled water was wrapped around a 30-cm-wide portion of the main stem of Chamaecyparis obtusa and Cryptomeria japonica trees during seasons of active cambium. Small blocks were collected from both cooled and non-cooled control portions of the stems for sequential observations of cambial activity and for anatomical measurements of cell morphology by light microscopy and image analysis. Key Results The effect of localized cooling was first observed on differentiating tracheids. Tracheids narrow in diameter and with significantly decreased cambial activity were evident 5 weeks after the start of cooling in these stems. Eight weeks after the start of cooling, tracheids with clearly diminished diameters and thickened cell walls were observed in these stems. Thus, localized low temperature induced narrow diameters and obvious thickening of secondary cell walls of tracheids, which were identified as latewood tracheids. Two months after the cessation of cooling, a false annual ring was observed and cambium became active again and produced new tracheids. In Cryptomeria japonica, cambial activity ceased earlier in locally cooled portions of stems than in non-cooled stems, indicating that the cambium had entered dormancy sooner in the cooled stems. Conclusions Artificial cooling of stems induced latewood formation and cessation of cambial activity, indicating that cambium and its derivatives can respond directly to changes in temperature. A decrease in the temperature of the stem is a critical factor in the control of cambial activity and xylem differentiation in trees. PMID:26703452

Localized cooling of stems induces latewood formation and cambial dormancy during seasons of active cambium in conifers.

PubMed

Begum, Shahanara; Kudo, Kayo; Matsuoka, Yugo; Nakaba, Satoshi; Yamagishi, Yusuke; Nabeshima, Eri; Rahman, Md Hasnat; Nugroho, Widyanto Dwi; Oribe, Yuichiro; Jin, Hyun-O; Funada, Ryo

2016-03-01

In temperate regions, trees undergo annual cycles of cambial growth, with periods of cambial activity and dormancy. Environmental factors might regulate the cambial growth, as well as the development of cambial derivatives. We investigated the effects of low temperature by localized cooling on cambial activity and latewood formation in two conifers, Chamaecyparis obtusa and Cryptomeria japonica. A plastic rubber tube that contained cooled water was wrapped around a 30-cm-wide portion of the main stem of Chamaecyparis obtusa and Cryptomeria japonica trees during seasons of active cambium. Small blocks were collected from both cooled and non-cooled control portions of the stems for sequential observations of cambial activity and for anatomical measurements of cell morphology by light microscopy and image analysis. The effect of localized cooling was first observed on differentiating tracheids. Tracheids narrow in diameter and with significantly decreased cambial activity were evident 5 weeks after the start of cooling in these stems. Eight weeks after the start of cooling, tracheids with clearly diminished diameters and thickened cell walls were observed in these stems. Thus, localized low temperature induced narrow diameters and obvious thickening of secondary cell walls of tracheids, which were identified as latewood tracheids. Two months after the cessation of cooling, a false annual ring was observed and cambium became active again and produced new tracheids. In Cryptomeria japonica, cambial activity ceased earlier in locally cooled portions of stems than in non-cooled stems, indicating that the cambium had entered dormancy sooner in the cooled stems. Artificial cooling of stems induced latewood formation and cessation of cambial activity, indicating that cambium and its derivatives can respond directly to changes in temperature. A decrease in the temperature of the stem is a critical factor in the control of cambial activity and xylem differentiation in trees. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evaluation of the maintenance of stemness, viability, and differentiation potential of gingiva-derived stem-cell spheroids.

PubMed

Lee, Sung-Il; Ko, Youngkyung; Park, Jun-Beom

2017-05-01

Gingiva-derived stem cells have been applied for tissue-engineering purposes and may be considered a favorable source of mesenchymal stem cells as harvesting stem cells from the mandible or maxilla may be performed with ease under local anesthesia. The present study was performed to fabricate stem-cell spheroids using concave microwells and to evaluate the maintenance of stemness, viability, and differentiation potential. Gingiva-derived stem cells were isolated, and the stem cells of 4×10 5 (group A) or 8×10 5 (group B) cells were seeded into polydimethylsiloxane-based, concave micromolds with 600 µm diameters. The morphology of the microspheres and the change of the diameters of the spheroids were evaluated. The viability of spheroids was qualitatively analyzed via Live/Dead kit assay. A cell viability analysis was performed on days 1, 3, 6, and 12 with Cell Counting Kit-8. The maintenance of stemness was evaluated with immunocytochemical staining using SSEA-4, TRA-1-60(R) (positive markers), and SSEA-1 (negative marker). Osteogenic, adipogenic, and chondrogenic differentiation potential was evaluated by incubating spheroids in osteogenic, adipogenic and chondrogenic induction medium, respectively. The gingiva-derived stem cells formed spheroids in the concave microwells. The diameters of the spheroids were larger in group A than in group B. The majority of cells in the spheroids emitted green fluorescence, indicating the presence of live cells at day 6. At day 12, the majority of cells in the spheroids emitted green fluorescence, and a small portion of red fluorescence was also noted, which indicated the presence of dead cells. The spheroids were positive for the stem-cell markers SSEA-4 and TRA-1-60(R) and were negative for SSEA-1, suggesting that these spheroids primarily contained undifferentiated human stem cells. Osteogenic, adipogenic, and chondrogenic differentiation was more evident with an increase of incubation time: Mineralized extracellular deposits were observed following Alizarin Red S staining at days 14 and 21; oil globules were increased at day 18 when compared with day 6; and Alcian blue staining was more evident at day 18 when compared with day 6. Within the limits of this study, stem-cell spheroids from gingival cells maintained the stemness, viability, and differentiation potential during the experimental periods. This method may be applied for a promising strategy for stem-cell therapy.

Stochasticity and Spatial Interaction Govern Stem Cell Differentiation Dynamics

NASA Astrophysics Data System (ADS)

Smith, Quinton; Stukalin, Evgeny; Kusuma, Sravanti; Gerecht, Sharon; Sun, Sean X.

2015-07-01

Stem cell differentiation underlies many fundamental processes such as development, tissue growth and regeneration, as well as disease progression. Understanding how stem cell differentiation is controlled in mixed cell populations is an important step in developing quantitative models of cell population dynamics. Here we focus on quantifying the role of cell-cell interactions in determining stem cell fate. Toward this, we monitor stem cell differentiation in adherent cultures on micropatterns and collect statistical cell fate data. Results show high cell fate variability and a bimodal probability distribution of stem cell fraction on small (80-140 μm diameter) micropatterns. On larger (225-500 μm diameter) micropatterns, the variability is also high but the distribution of the stem cell fraction becomes unimodal. Using a stochastic model, we analyze the differentiation dynamics and quantitatively determine the differentiation probability as a function of stem cell fraction. Results indicate that stem cells can interact and sense cellular composition in their immediate neighborhood and adjust their differentiation probability accordingly. Blocking epithelial cadherin (E-cadherin) can diminish this cell-cell contact mediated sensing. For larger micropatterns, cell motility adds a spatial dimension to the picture. Taken together, we find stochasticity and cell-cell interactions are important factors in determining cell fate in mixed cell populations.

Use of a Non-Metric Digital Camera for Tree Stem Evaluation

Treesearch

Neil Clark; Randolph H. Wynne; Daniel L. Schmoldt; Philip A. Araman; Matthew F. Winn

1998-01-01

We are investigating the use of a commercially-available solid-state matrix camera as a dendrometer for tree stem measurements. Thirty-two images of four hardwood stems were used to measure 54 diameters at various heights on the stems ranging from 1.4 m to 21 m. These measurements were compared to caliper measurements taken at the same heights. The percent inaccuracy...

Stand dynamics following gap-scale exogenous disturbance in a single cohort mixed species stand in Morgan County, Tennessee

Treesearch

Brian S. Hughett; Wayne K. Clatterbuck

2014-01-01

Differences in composition, structure, and growth under canopy gaps created by the mortality of a single stem were analyzed using analysis of variance under two scenarios, with stem removed or with stem left as a standing snag. There were no significant differences in composition and structure of large diameter residual stems within upper canopy strata. Some...

Evidence for xylem adaptations to drought in ancient Cordaites of the Carboniferous

NASA Astrophysics Data System (ADS)

Medeiros, J. S.; Hewins, C.; Serbet, R.; Taylor, T. N.; Taylor, E. L.; Ward, J. K.

2013-12-01

Ancient land plants faced the same challenges to growth and survival as modern land plants, including the need to resist xylem embolisms imposed by drought in order to main water supply to leaves. Cordaites, considered to be ancestors of the conifers, were some of the first trees on Earth and are often described as the most drought resistant plants in the North American landscape from the Late Missisipian (~320 MYA) to the early Permian (~250 MYA). Cordaites were common in both mires and dry uplands, however, suggesting considerable variation in drought tolerance, but neither the extent of this variation nor the particular xylem features associated with dryland habitats have been previously examined. We measured xylem anatomical traits including tracheid diameter (D) and wall thickness (t), for Cordaites roots and stems from three sites in Central North America: What Cheer IA, Sahara IL and Lewis Creek KY. From these data we calculated mechanical strength (t/b), which was used to estimate vulnerability to drought embolism (P50) based on comparisons with modern plants. In addition, we used the model of Wilson et al. (2008) to calculate the specific conductivity (Ksp), a measure of xylem water transport capacity. D and Ksp of Cordaites stems were similar to that typical of modern conifers but t/b tended to be lower. However, Cordaites exhibited significant variation in D, t, Ksp and t/b across sites. Stem P50 estimated from comparisons with modern plants ranged from approximately -4 at Lewis Creek to as low as -7 MPa at Sahara. We also found differences between stems and roots for Cordaites. Compared to stems, roots had larger D and higher Ksp, but lower t and t/b, resulting in a P50 ranging from approximately -2 to -4 MPa. In the roots of Sahara Cordaites, lower t/b in roots was a result of both significantly larger conduits and significantly thinner conduit walls compared to stems. Thus, hydraulic segmentation in Cordaites could have facilitated their survival in drier upland habitats, as root embolisms early on during drought could have hydraulically isolated the plant from drying soil. Our data suggest that Cordaites were similar in water transport properties but with low to moderate drought tolerance compared to modern conifers. Observation that Cordaites water transport properties varied across sites supports the idea that they were an ecological diverse plant group. Furthermore, Cordaites from Sahara exhibited a suite of traits typical of modern drought adapted plants, including: low D and Ksp combined with greater t, higher t/b and greater differentiation in t/b between roots and stems. Thus, we provide evidence from fossilized plants that associations between xylem features and habitat, as well as some modern drought adaptations, may be nearly as old as trees themselves.

Liana abundance, diversity, and distribution on Barro Colorado Island, Panama.

PubMed

Schnitzer, Stefan A; Mangan, Scott A; Dalling, James W; Baldeck, Claire A; Hubbell, Stephen P; Ledo, Alicia; Muller-Landau, Helene; Tobin, Michael F; Aguilar, Salomon; Brassfield, David; Hernandez, Andres; Lao, Suzanne; Perez, Rolando; Valdes, Oldemar; Yorke, Suzanne Rutishauser

2012-01-01

Lianas are a key component of tropical forests; however, most surveys are too small to accurately quantify liana community composition, diversity, abundance, and spatial distribution - critical components for measuring the contribution of lianas to forest processes. In 2007, we tagged, mapped, measured the diameter, and identified all lianas ≥1 cm rooted in a 50-ha plot on Barro Colorado Island, Panama (BCI). We calculated liana density, basal area, and species richness for both independently rooted lianas and all rooted liana stems (genets plus clones). We compared spatial aggregation patterns of liana and tree species, and among liana species that varied in the amount of clonal reproduction. We also tested whether liana and tree densities have increased on BCI compared to surveys conducted 30-years earlier. This study represents the most comprehensive spatially contiguous sampling of lianas ever conducted and, over the 50 ha area, we found 67,447 rooted liana stems comprising 162 species. Rooted lianas composed nearly 25% of the woody stems (trees and lianas), 35% of woody species richness, and 3% of woody basal area. Lianas were spatially aggregated within the 50-ha plot and the liana species with the highest proportion of clonal stems more spatially aggregated than the least clonal species, possibly indicating clonal stem recruitment following canopy disturbance. Over the past 30 years, liana density increased by 75% for stems ≥1 cm diameter and nearly 140% for stems ≥5 cm diameter, while tree density on BCI decreased 11.5%; a finding consistent with other neotropical forests. Our data confirm that lianas contribute substantially to tropical forest stem density and diversity, they have highly clumped distributions that appear to be driven by clonal stem recruitment into treefall gaps, and they are increasing relative to trees, thus indicating that lianas will play a greater role in the future dynamics of BCI and other neotropical forests.

Diversity of hydraulic traits in nine Cordia species growing in tropical forests with contrasting precipitation.

PubMed

Choat, Brendan; Sack, Lawren; Holbrook, N Michele

2007-01-01

Inter- and intraspecific variation in hydraulic traits was investigated in nine Cordia (Boraginaceae) species growing in three tropical rainforests differing in mean annual precipitation (MAP). Interspecific variation was examined for the different Cordia species found at each site, and intraspecific variation was studied in populations of the widespread species Cordia alliodora across the three sites. Strong intra- and interspecific variation were observed in vulnerability to drought-induced embolism. Species growing at drier sites were more resistant to embolism than those growing at moister sites; the same pattern was observed for populations of C. alliodora. By contrast, traits related to hydraulic capacity, including stem xylem vessel diameter, sapwood specific conductivity (K(s)) and leaf specific conductivity (K(L)), varied strongly but independently of MAP. For C. alliodora, xylem anatomy, K(s), K(L) and Huber value varied little across sites, with K(s) and K(L) being consistently high relative to other Cordia species. A constitutively high hydraulic capacity coupled with plastic or genotypic adjustment in vulnerability to embolism and leaf water relations would contribute to the ability of C. alliodora to establish and compete across a wide precipitation gradient.

Growth and wood/bark properties of Abies faxoniana seedlings as affected by elevated CO2.

PubMed

Qiao, Yun-Zhou; Zhang, Yuan-Bin; Wang, Kai-Yun; Wang, Qian; Tian, Qi-Zhuo

2008-03-01

Growth and wood and bark properties of Abies faxoniana seedlings after one year's exposure to elevated CO2 concentration (ambient + 350 (+/- 25) micromol/mol) under two planting densities (28 or 84 plants/m(2)) were investigated in closed-top chambers. Tree height, stem diameter and cross-sectional area, and total biomass were enhanced under elevated CO2 concentration, and reduced under high planting density. Most traits of stem bark were improved under elevated CO2 concentration and reduced under high planting density. Stem wood production was significantly increased in volume under elevated CO2 concentration under both densities, and the stem wood density decreased under elevated CO2 concentration and increased under high planting density. These results suggest that the response of stem wood and bark to elevated CO2 concentration is density dependent. This may be of great importance in a future CO2 enriched world in natural forests where plant density varies considerably. The results also show that the bark/wood ratio in diameter, stem cross-sectional area and dry weight are not proportionally affected by elevated CO2 concentration under the two contrasting planting densities. This indicates that the response magnitude of stem bark and stem wood to elevated CO2 concentration are different but their response directions are the same.

Machine vision system for measuring conifer seedling morphology

NASA Astrophysics Data System (ADS)

Rigney, Michael P.; Kranzler, Glenn A.

1995-01-01

A PC-based machine vision system providing rapid measurement of bare-root tree seedling morphological features has been designed. The system uses backlighting and a 2048-pixel line- scan camera to acquire images with transverse resolutions as high as 0.05 mm for precise measurement of stem diameter. Individual seedlings are manually loaded on a conveyor belt and inspected by the vision system in less than 0.25 seconds. Designed for quality control and morphological data acquisition by nursery personnel, the system provides a user-friendly, menu-driven graphical interface. The system automatically locates the seedling root collar and measures stem diameter, shoot height, sturdiness ratio, root mass length, projected shoot and root area, shoot-root area ratio, and percent fine roots. Sample statistics are computed for each measured feature. Measurements for each seedling may be stored for later analysis. Feature measurements may be compared with multi-class quality criteria to determine sample quality or to perform multi-class sorting. Statistical summary and classification reports may be printed to facilitate the communication of quality concerns with grading personnel. Tests were conducted at a commercial forest nursery to evaluate measurement precision. Four quality control personnel measured root collar diameter, stem height, and root mass length on each of 200 conifer seedlings. The same seedlings were inspected four times by the machine vision system. Machine stem diameter measurement precision was four times greater than that of manual measurements. Machine and manual measurements had comparable precision for shoot height and root mass length.

Genetic variation for susceptibility to storm-induced stem breakage in Solidago altissima: The role of stem height and morphology

NASA Astrophysics Data System (ADS)

Wise, Michael J.; Abrahamson, Warren G.

2010-07-01

While storms can have obvious ecological impacts on plants, plants' potential to respond evolutionarily to selection for increased resistance to storm damage has received little study. We took advantage of a thunderstorm with strong wind and hail to examine genetic variation for resistance to stem breakage in the herbaceous perennial Solidago altissima. The storm broke the apex of nearly 10% of 1883 marked ramets in a common-garden plot containing 26 genets of S. altissima. Plant genets varied 20-fold in resistance to breakage. Stem height was strongly correlated with resistance to breakage, with taller stems being significantly more susceptible. A stem's growth form (erect versus nodding) had no detectable effect on its resistance to breakage. Therefore, we rejected the hypothesis that a function of the nodding, or "candy-cane," morphology is protection of the apex from storm damage. The significant genetic variation in S. altissima for stem breakage suggests that this plant has the capacity to respond to selection imposed by storms - particularly through changes in mean stem height. Tradeoffs between breakage resistance and competition for light and pollinators may act to maintain a large amount of genetic variation in stem height.

Taper Functions for Predicting Product Volumes in Natural Shortleaf Pines

Treesearch

Robert M. Farrar; Paul A. Murphy

1987-01-01

Taper (stem-profile) functions are presented for natural shortleaf pine (Pinus echinata Mill.) trees growing in the West Gulf area. These functions, when integrated, permit the prediction of volume between any two heights on a stem and, conversely by iteration, the volume between any two diameters on a stem. Examples are given of use of the functions...

Dry Weight of Several Piedmont Hardwoods

Treesearch

Bobby G. Blackmon; Charles W. Ralston

1968-01-01

Forty-four sample hardwood trees felled on 24 plots were separated into three above-ground components- stem, branches, and leaves--and weighed for dry matter content. Tree, stand, and site variables were tested for significant relationships with dry weight of tree parts. Weight increase of stems was a logarithmic function ,of both stem diameter and height, whereas for...

A diameter growth model for single-stem growth forms for the interior west forest inventory and analysis’s region

Treesearch

Michael T. Thompson

2015-01-01

The Interior West Forest Inventory and Analysis Unit (IWFIA) will soon transition from a regional system to a national FIA system for compiling estimates of forest growth, removals, and mortality. The national system requires regional diameter-growth models to estimate diameters on trees in situations where the initial or terminal diameter is not known at the beginning...

Growth phenology of coast Douglas-fir seed sources planted in diverse environments.

PubMed

Gould, Peter J; Harrington, Constance A; St Clair, J Bradley

2012-12-01

The timing of periodic life cycle events in plants (phenology) is an important factor determining how species and populations will react to climate change. We evaluated annual patterns of basal-area and height growth of coast Douglas-fir (Pseudotusga menziesii var. menziesii (Mirb.) Franco) seedlings from four seed sources that were planted in four diverse environments as part of the Douglas-fir Seed-Source Movement Trial. Stem diameters and heights were measured periodically during the 2010 growing season on 16 open-pollinated families at each study installation. Stem diameters were measured on a subset of trees with electronic dendrometers during the 2010 and 2011 growing seasons. Trees from the four seed sources differed in phenology metrics that described the timing of basal-area and height-growth initiation, growth cessation and growth rates. Differences in the height-growth metrics were generally larger than differences in the basal-area growth metrics and differences among installations were larger than differences among seed sources, highlighting the importance of environmental signals on growth phenology. Variations in the height- and basal-area growth metrics were correlated with different aspects of the seed-source environments: precipitation in the case of height growth and minimum temperature in the case of basal-area growth. The detailed dendrometer measurements revealed differences in growth patterns between seed sources during distinct periods in the growing season. Our results indicate that multiple aspects of growth phenology should be considered along with other traits when evaluating adaptation of populations to future climates.

The Power of the Rhythm of Tree Stems

NASA Astrophysics Data System (ADS)

Steppe, K.

2015-12-01

On annual and monthly scales, a remarkable close relationship has been shown between net ecosystem productivity (NEP) measured by eddy covariance and stem diameter variations (SDV) measured with automated point dendrometers in a Swiss subalpine Norway spruce forest (Zweifel et al. 2010). Causality for the close NEP-SDV relationship is poorly understood, but radial stem growth has been suggested to play a crucial role. Despite its huge ecological implications, and being 'hot' in anatomical, ecophysiologial, and ecological disciplines, radial stem growth in trees remains poorly understood (Steppe et al. 2015). While high-resolution SDV mirror a source of tree physiological information, unambiguous interpretation of dendrometer readings is more complicated than it appears at first sight, with a great potential still waiting to be discovered (De Swaef et al. 2015, Zweifel 2015). Also an integrative framework to assess impacts of climate on stem growth is still lacking, although such a theory is very much needed to predict annual tree growth patterns as well as future production and carbon sequestration potential of forests (Steppe et al. 2015). In this keynote lecture, I will present the major fluxes and pools of water and carbon inside a stem segment of a tree. I will examine diel dynamics in radial stem growth from underlying water and carbon mechanisms under wet and dry conditions, distinguishing between known patterns and processes, and more speculative ones. Discussions will be based on observations in the different research disciplines, but also result from mechanistic plant models aiming at integration. Based on this, I will show missing pieces that might be critical to build an integrative theory to understand causes and consequences of tree stem growth. Addressing these key-missing pieces of information may help improving quantification of terrestrial ecosystem carbon uptake and storage. ReferencesDe Swaef et al. (2015) Tree Physiology (in press). Steppe et al. (2015) Trends in Plant Science 20: 335-343. Zweifel et al. (2010) New Phytologist 187: 819-830. Zweifel (2015) Plant, Cell & Environment (in press).

Lunar Rhythms In Forestry Traditions - Lunar-Correlated Phenomena In Tree Biology And Wood Properties

NASA Astrophysics Data System (ADS)

Zürcher, Ernst

For more than 2000 years, certain forestry practices and rules regarding tree felling have been carried out in observance to Moon cycles. A general review of the different types of rules followed (known in Europe and on other continents and stemming from both written sources and current practitioners) shows that special timber uses are mentioned in relation to a specific felling date which supposedly ensures advantageous wood properties. These empirical forestry traditions apply to a range of wood uses as diverse as building timber, shingles, wooden chimneys, fuel wood, resonance wood for harmony tables of violins, cheese-boxes, barrels and ploughs. In each of these cases, felling at the ``right date'' is thought to be an important factor to ensure the required properties of the product. Moreover, the rafting of timber used to be limited to certain days of the Moon cycle, when the water was supposed to carry the wood in the best way. The second part presents scientific studies concerned, on the one hand, with ``Moon phases'' factor. They deal with elements of tree biology such as germination and initial growth of tropical trees (where strong and systematic variations and their complicating aspects have been observed), insect attacks on trees and reversible fluctuations of stem diameters. On the other hand, some works concentrate on wood properties and the relation between wood and water. They deal with the durability of wood, with systematic density variations after kiln-drying and with variations in the compression strength of the corresponding samples. An overview tries to find a common link between empirical practices and the scientific results.

Improving estimation of tree carbon stocks by harvesting aboveground woody biomass within airborne LiDAR flight areas

NASA Astrophysics Data System (ADS)

Colgan, M.; Asner, G. P.; Swemmer, A. M.

2011-12-01

The accurate estimation of carbon stored in a tree is essential to accounting for the carbon emissions due to deforestation and degradation. Airborne LiDAR (Light Detection and Ranging) has been successful in estimating aboveground carbon density (ACD) by correlating airborne metrics, such as canopy height, to field-estimated biomass. This latter step is reliant on field allometry which is applied to forest inventory quantities, such as stem diameter and height, to predict the biomass of a given tree stem. Constructing such allometry is expensive, time consuming, and requires destructive sampling. Consequently, the sample sizes used to construct such allometry are often small, and the largest tree sampled is often much smaller than the largest in the forest population. The uncertainty resulting from these sampling errors can lead to severe biases when the allometry is applied to stems larger than those harvested to construct the allometry, which is then subsequently propagated to airborne ACD estimates. The Kruger National Park (KNP) mission of maintaining biodiversity coincides with preserving ecosystem carbon stocks. However, one hurdle to accurately quantifying carbon density in savannas is that small stems are typically harvested to construct woody biomass allometry, yet they are not representative of Kruger's distribution of biomass. Consequently, these equations inadequately capture large tree variation in sapwood/hardwood composition, root/shoot/leaf allocation, branch fall, and stem rot. This study eliminates the "middleman" of field allometry by directly measuring, or harvesting, tree biomass within the extent of airborne LiDAR. This enables comparisons of field and airborne ACD estimates, and also enables creation of new airborne algorithms to estimate biomass at the scale of individual trees. A field campaign was conducted at Pompey Silica Mine 5km outside Kruger National Park, South Africa, in Mar-Aug 2010 to harvest and weigh tree mass. Since harvesting of trees is not possible within KNP, this was a unique opportunity to fell trees already scheduled to be cleared for mining operations. The area was first flown by the Carnegie Airborne Observatory in early May, prior to harvest, to enable correlation of LiDAR-measured tree height and crown diameter to harvested tree mass. Results include over 4,000 harvested stems and 13 species-specific biomass equations, including seven Kruger woody species previously without allometry. We found existing biomass stem allometry over-estimates ACD in the field, whereas airborne estimates based on harvest data avoid this bias while maintaining similar precision to field-based estimates. Lastly, a new airborne algorithm estimating biomass at the tree-level reduced error from tree canopies "leaning" into field plots but whose stems are outside plot boundaries. These advances pave the way to better understanding of savanna and forest carbon density at landscape and regional scales.

[Effects of precipitation and interspecific competition on Quercus mongolica and pinus koraiensis seedlings growth].

PubMed

Wu, Jing-Lian; Wang, Miao; Lin, Fei; Hao, Zhan-Qing; Ji, Lan-Zhu; Liu, Ya-Qin

2009-02-01

Aiming at the variation of precipitation pattern caused by global warming, a field simulation experiment was conducted to study the effects of 30% increase (+W) and decrease (-W) of precipitation on the morphology, growth, and biomass partitioning of mono- and mixed cultured seedlings of Quercus mongolica and Pinus koraiensis, the two dominant tree species in temperate broad-leaved Korean pine mixed forest in Changbai Mountains. Comparing with monoculture, mixed culture increased the canopy width and main root length of Q. mongolica seedlings, but decreased the basal diameter, plant height, leaf number, and dry masses of root, stem, leaf and whole plant of P. koraiensis seedlings significantly. Treatment (-W) increased the stem/mass ratio while decreased the main root length of Q. mongolica seedlings, and decreased the main root length, leaf number, dry masses of leaf and whole plant, and leaf/mass ratio, while increased the stem/mass ratio of P. koraiensis seedlings significantly, compared with treatment CK. Treatment (+W) had no significant effect on these indices of the two species. At early growth stage, interspecific competition and precipitation pattern had significant effects on the morphology and growth of the seedlings, and the responses were much stronger for P. koraiensis than for Q. mongolica.

Long-term diameter growth for trees in the Cinnamon Bay Watershed

Treesearch

Peter L. Weaver

2009-01-01

From 1983 to 2008, the mean annual diameter growth (MAI) for 1,402 surviving stems of 62 species in the Cinnamon Bay watershed was 0.08¡À0.002 cm yr-1. Long-term MAI ranged from 0.02 cm yr-1 for Randia aculeata to 0.23 cm yr-1 for Inga laurina. Of the 30 species with ¡Ý8 surviving stems, eight averaged ¡Ý0.10 cm yr-1. Hurricane Hugo in 1989, Hurricane Marilyn in 1995,...

Stem phototropism of trees: a possible significant factor in determining stem inclination on forest slopes.

PubMed

Matsuzaki, Jun; Masumori, Masaya; Tange, Takeshi

2006-09-01

The main stems of trees on forest slopes incline down the slope to various extents that are characteristic of the species. The inclination has been explained as an active response to a horizontally asymmetrical light environment, but the contributing physiological mechanisms are unknown. The present study tested the hypothesis that stem phototropism, gravitropism, or a combination of the two determines the inclination of tree stems on forest slopes. Cryptomeria japonica, Pinus densiflora, Quercus myrsinaefolia and Q. serrata were studied. Measurements were made of stem inclination of mature trees on forest slopes in uniform plantations of each species, and changes in stem inclination of potted seedlings in response to illumination treatments (unilateral or overhead) and inclination treatments (artificially inclined or erect). Indices of phototropic and gravitropic responsiveness were evaluated for each species, calculated from the change in stem inclination in response to artificial inclination with unilateral or overhead illumination. Stem inclination on forest slopes varied significantly among species: Q. serrata inclined most in the down-slope direction, C. japonica inclined the least, and P. densiflora and Q. myrsinaefolia were intermediate. The change in stem inclination of seedlings in each treatment varied significantly among species. One-year-old stems of Q. serrata and 2-year-old stems of Q. myrsinaefolia bent toward the light source. Interspecific variation in the change in stem inclination in response to the unilateral illumination or that in the index of phototropic responsiveness was strongly correlated with the variation in stem inclination on forest slopes. The orientation of woody stems that have finished elongation can be actively controlled by phototropism. Interspecific variation in phototropic responsiveness of trees is a possible significant determinant of interspecific variation in stem inclination on forest slopes.

Stem Phototropism of Trees: A Possible Significant Factor in Determining Stem Inclination on Forest Slopes

PubMed Central

MATSUZAKI, JUN; MASUMORI, MASAYA; TANGE, TAKESHI

2006-01-01

• Background and Aims The main stems of trees on forest slopes incline down the slope to various extents that are characteristic of the species. The inclination has been explained as an active response to a horizontally asymmetrical light environment, but the contributing physiological mechanisms are unknown. The present study tested the hypothesis that stem phototropism, gravitropism, or a combination of the two determines the inclination of tree stems on forest slopes. • Methods Cryptomeria japonica, Pinus densiflora, Quercus myrsinaefolia and Q. serrata were studied. Measurements were made of stem inclination of mature trees on forest slopes in uniform plantations of each species, and changes in stem inclination of potted seedlings in response to illumination treatments (unilateral or overhead) and inclination treatments (artificially inclined or erect). Indices of phototropic and gravitropic responsiveness were evaluated for each species, calculated from the change in stem inclination in response to artificial inclination with unilateral or overhead illumination. • Key Results Stem inclination on forest slopes varied significantly among species: Q. serrata inclined most in the down-slope direction, C. japonica inclined the least, and P. densiflora and Q. myrsinaefolia were intermediate. The change in stem inclination of seedlings in each treatment varied significantly among species. One-year-old stems of Q. serrata and 2-year-old stems of Q. myrsinaefolia bent toward the light source. Interspecific variation in the change in stem inclination in response to the unilateral illumination or that in the index of phototropic responsiveness was strongly correlated with the variation in stem inclination on forest slopes. • Conclusions The orientation of woody stems that have finished elongation can be actively controlled by phototropism. Interspecific variation in phototropic responsiveness of trees is a possible significant determinant of interspecific variation in stem inclination on forest slopes. PMID:16790467

Impacts of environmental factors on the climbing behaviors of herbaceous stem-twiners.

PubMed

Hu, Liang; Chen, Youfang; Liu, Meicun

2017-11-01

The curvature of the helical trajectory formed by herbaceous stem-twiners has been hypothesized to be constant on uniformly sized cylindrical supports and remains constant on different supports varying in diameter. However, experimental studies on the constant curvature hypothesis have been very limited. Here, we tested the hypothesis in a series of experiments on five herbaceous stem-twiners ( Ipomoea triloba , Ipomoea nil , Phaseolus vulgaris , Vigna unguiculata, and Mikania micrantha ). We investigated how internode characteristics (curvature [β], diameter [ d ], and length [ L ]) and success rate (SR) of twining shoots would be affected by support thickness ( D ), temperature ( T ), illumination, and support inclination. The results showed that: (1) the SR of tested species decreased, but d increased with increasing support thickness. The β of the twining shoots on erect cylindrical poles was not constant, but it decreased with increasing d or support thickness. (2) The SR of tested species was not obviously reduced under low-temperature conditions, but their β was significantly higher and d significantly lower when temperature was more than 5°C lower. (3) The SR , d, and L of two tested Ipomoea species significantly declined, but β increased under 50% shading stress. (4) The curvatures of upper semicycles of I. triloba shoots on 45° inclined supports were not significantly different from curvatures of those shoots climb on erect supports, whereas the curvatures of lower semicycles were 40%-72% higher than curvatures of upper semicycles. Synthesis : Our study illustrates that stem curvatures of a certain herbaceous stem-twiners are not constant, but rather vary in response to external support, temperature, and illumination conditions. We speculate that herbaceous stem-twiners positively adapt to wide-diameter supports by thickening their stems and by reducing their twining curvatures. This insight helps us better understand climbing processes and dynamics of stem-twiners in forest communities and ecosystems.

The effects of age and environment on the expression of inbreeding depression in Eucalyptus globulus

PubMed Central

Costa e Silva, J; Hardner, C; Tilyard, P; Potts, B M

2011-01-01

Inbreeding adversely affects fitness traits in many plant and animal species, and the magnitude, stability and genetic basis of inbreeding depression (ID) will have short- and long-term evolutionary consequences. The effects of four degrees of inbreeding (selfing, f=50% full- and half-sib matings, f=25 and 12.5% and unrelated outcrosses, f=0%) on survival and growth of an island population of Eucalyptus globulus were studied at two sites for over 14 years. For selfs, ID in survival increased over time, reaching a maximum of 49% by age 14 years. However, their inbreeding depression for stem diameter remained relatively stable with age, and ranged from 28 to 36% across years and sites. ID for survival was markedly greater on the more productive site, possibly due to greater and earlier onset of inter-tree competition, but was similar on both sites for the diameter of survivors. The deleterious trait response to increasing inbreeding coefficients was linear for survival and diameter. Non-significant quadratic effects suggested that epistasis did not contribute considerably to the observed ID at the population level. Among- and within-family coefficients of variation for diameter increased with inbreeding degree, and the variance among the outcrossed families was significant only on the more productive site. The performance of self-families for diameter was highly stable between sites. This suggests that, for species with mixed mating systems, environmentally stable inbreeding effects in open-pollinated progenies may tend to mask the additive genotype-by-environment interaction for fitness traits and the adaptive response to the environment. PMID:21224873

The role of genetic and chemical variation of Pinus sylvestris seedlings in influencing slug herbivory.

PubMed

O'Reilly-Wapstra, Julianne M; Iason, Glenn R; Thoss, Vera

2007-05-01

This study investigated the genetic and chemical basis of resistance of Pinus sylvestris seedlings to herbivory by a generalist mollusc, Arion ater. Using feeding trials with captive animals, we examined selective herbivory by A. ater of young P. sylvestris seedlings of different genotypes and correlated preferences with seedling monoterpene levels. We also investigated the feeding responses of A. ater to artificial diets laced with two monoterpenes, Delta(3)-carene and alpha-pinene. Logistic regression indicated that two factors were the best predictors of whether seedlings in the trial would be consumed. Individual slug variation (replicates) was the most significant factor in the model; however, alpha-pinene concentration (also representing beta-pinene, Delta(3)-carene and total monoterpenes due to multicollinearity) of needles was also a significant factor. While A. ater did not select seedlings on the basis of family, seedlings not eaten were significantly higher in levels of alpha-pinene compared to seedlings that were consumed. We also demonstrated significant genetic variation in alpha-pinene concentration of seedlings between different families of P. sylvestris. Nitrogen and three morphological seedling characteristics (stem length, needle length and stem diameter) also showed significant genetic variation between P. sylvestris families. Artificial diets laced with high (5 mg g(-1) dry matter) quantities of either Delta(3)-carene or alpha-pinene, were eaten significantly less than control diets with no added monoterpenes, supporting the results of the seedling feeding trial. This study demonstrates that A. ater selectively feed on P. sylvestris seedlings and that this selection is based, in part, on the monoterpene concentration of seedlings. These results, coupled with significant genetic variation in alpha-pinene concentration of seedlings and evidence that slug herbivory is detrimental to P. sylvestris fitness, are discussed as possible evidence for A. ater as a selective force on the evolution of defensive chemistry in P. sylvestris.

Taper-based system for estimating stem volumes of upland oaks

Treesearch

Donald E. Hilt

1980-01-01

A taper-based system for estimating stem volumes is developed for Central States upland oaks. Inside bark diameters up the stem are predicted as a function of dbhib, total height, and powers and relative height. A Fortran IV computer program, OAKVOL, is used to predict cubic and board-foot volumes to any desired merchantable top dib. Volumes of...

Intensive management influence on Douglas-fir stem form, branch characteristics, and simulated product recovery

Treesearch

A.R. Weiskittel; R.A. Monserud; R. Rose; E.C. Turnblom; Douglas A. Maguire

2006-01-01

Intensive management may adversely affect lumber yield and quality by increasing knot size and creating a more conical stem form with a greater average rate of taper. This study was initiated to examine the impact of management on simulated lumber yield and quality. Stem diameter and branch size and location of 223 Pseudotsuga menziesii (Mirb.)...

Band-filling of solution-synthesized CdS nanowires.

PubMed

Puthussery, James; Lan, Aidong; Kosel, Thomas H; Kuno, Masaru

2008-02-01

The band edge optical characterization of solution-synthesized CdS nanowires (NWs) is described. Investigated wires are made through a solution-liquid-solid approach that entails the use of low-melting bimetallic catalyst particles to seed NW growth. Resulting diameters are approximately 14 nm, and lengths exceed 1 microm. Ensemble diameter distributions are approximately 13%, with corresponding intrawire diameter variations of approximately 5%. High-resolution transmission electron micrographs show that the wires are highly crystalline and have the wurtzite structure with growth along at least two directions: [0001] and [1010]. Band edge emission is observed with estimated quantum yields between approximately 0.05% and 1%. Complementary photoluminescence excitation spectra show structure consistent with the linear absorption. Carrier cooling dynamics are subsequently examined through ensemble lifetime and transient differential absorption measurements. The former reveals unexpectedly long band edge decays that extend beyond tens of nanoseconds. The latter indicates rapid intraband carrier cooling on time scales of 300-400 fs. Subsequent recovery at the band edge contains significant Auger contributions at high intensities which are usurped by other, possibly surface-related, carrier relaxation pathways at lower intensities. Furthermore, an unusual intensity-dependent transient broadening is seen, connected with these long decays. The effect likely stems from band-filling on the basis of an analysis of observed spectral shifts and line widths.

[Effects of different irrigations on the water physiological characteristics of Haloxylon ammodendron in Taklimakan Desert hinterland].

PubMed

Xie, Ting-ting; Zhang, Xi-ming; Liang, Shao-min; Shan, Li-shan; Yang, Xiao-lin; Hua, Yong-hui

2008-04-01

By using heat-balance stem flow gauge and press chamber, the water physiological characteristics of Haloxylon ammodendron under different irrigations in Taklimakan Desert hinterland were measured and analyzed. The results indicated that the diurnal variation curve of H. ammodendron stem sap flow varied with irrigations. When irrigated 35 and 24.5 kg x plant(-1) once time, the diurnal variation of stem sap flow changed in single peak curve and the variation extent was higher; while irrigated 14 kg x plant(-1) once time, the diurnal variation changed in two-peak curve and the variation extent was small. With the decrease of irrigations, the average daily sap flow rate and the daily water consumption of H. ammodendron decreased gradually, the dawn and postmeridian water potential also had a gradual decrease, and the correlations of stem sap flow with total radiation, air temperature, relative humidity, and wind speed enhanced. Under different irrigations, the correlation between stem sap flow rate and total radiation was always the best.

Effects of an acute dose of gamma radiation exposure on stem diameter growth, carbon gain, and biomass partitioning in Helianthus annuus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thiede, M.E.

1988-05-25

Nineteen-day-old dwarf sunflower plants (Helianthus annuus, variety NK894) received a variable dose (0-40 Gy) from a cobalt-60 gamma source. A very sensitive stem monitoring device, developed at Battelle's Pacific Northwest Laboratories, Richland, Washington was used to measure real-time changes in stem diameter. Exposure of plants caused a significant reduction in stem growth and root biomass. Doses as low as 5 Gy resulted in a significant increase in leaf density, suggesting that nonreversible morphological growth changes could be induced by very low doses of radiation. Carbohydrate analysis of 40-Gy irradiated plants demonstrated significantly more starch content in leaves and significantly lessmore » starch content in stems 18 days after exposure than did control plants. In contrast, the carbohydrate content in roots of 40-Gy irradiated plants were not significantly different from unirradiated plants 18 days after exposure. These results indicate that radiation either decreased phloem transport or reduced the availability of sugar reducing enzymes in irradiated plants. 44 refs., 12 figs.« less

Morphology, nurse plants, and minimum apical temperatures for young Carnegiea gigantea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobel, P.S.

1980-06-01

The northern limit of Carnegiea gigantea (Engelm.) Britton and Rose apparently depends on minimum apical temperatures. Diameters, apical spine coverage, and effects of nurse plants on incoming long-wave (infrared (ir)) radiation, all of which affect apical temperatures, were therefore determined for stems of C. gigantea up to 4 m tall at four sites along a north-south transect in Arizona. A simulation model indicated that the increase in diameter accompanying stem growth raised the minimum apical temperature more than 3 C. Thus, plants with the shortest stems would be expected to be the most vulnerable to freezing damage; indeed, freezing damagemore » on stems <0.5 m tall without nurse plants was fairly common at the colder sites. Nurse plants obstructed a greater portion of the sky for C. gigantea at the colder sites; e.g., the effective environmental temperature for ir radiation at such locations was raised more than 10 C for stems under 1 m tall. If the northern limit of C. gigantea reflects wintertime survival of juveniles, nurse plants could extend the range by offering some protection against freezing.« less

[Seedling index of Salvia miltiorrhiza and its simulation model].

PubMed

Huang, Shu-Hua; Xu, Fu-Li; Wang, Wei-Ling; Du, Jun-Bo; Ru, Mei; Wang, Jing; Cao, Xian-Yan

2012-10-01

Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings and seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling's health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) x plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling's quality. The coefficient of determination (R2) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors.

A computational algorithm addressing how vessel length might depend on vessel diameter

Treesearch

Jing Cai; Shuoxin Zhang; Melvin T. Tyree

2010-01-01

The objective of this method paper was to examine a computational algorithm that may reveal how vessel length might depend on vessel diameter within any given stem or species. The computational method requires the assumption that vessels remain approximately constant in diameter over their entire length. When this method is applied to three species or hybrids in the...

Growth reponses of eggplant and soybean seedlings to mechanical stress in greenhouse and outdoor environments

NASA Technical Reports Server (NTRS)

Latimer, J. G.; Pappas, T.; Mitchell, C. A.

1986-01-01

Eggplant (Solanum melongena L. var. esculentum 'Burpee's Black Beauty') and soybean [Glycine max (L.) Merr. 'Wells II'] seedlings were assigned to a greenhouse or a windless or windy outdoor environment. Plants within each environment received either periodic seismic (shaking) or thigmic (flexing or rubbing) treatment, or were left undisturbed. Productivity (dry weight) and dimensional (leaf area and stem length) growth parameters generally were reduced more by mechanical stress in the greenhouse (soybean) or outdoor-windless environment (eggplant) than in the outdoor windy environment. Outdoor exposure enhanced both stem and leaf specific weights, whereas mechanical stress enhanced only leaf specific weight. Although both forms of controlled mechanical stress tended to reduce node and internode diameters of soybean, outdoor exposure increased stem diameter.

Eucalyptus grandis Hill ex Maiden inoculated with Pisolithus microcarpus (UFSC-Pt116) in land subject to the sandy process in Southern Brazil

PubMed Central

de Souza, Eduardo Lorensi; Antoniolli, Zaida Inês; Machado, Rafael Goulart; Eckhardt, Daniel Pazzini; Dahmer, Sabrina de Fátima Barbosa

2014-01-01

Eucalypts is one of the main species used for commercial reforestation in the Rio Grande do Sul State, Brazil. This study aimed to evaluate the survival and early growth of eucalyptus trees in an area subject to sandy process after three years of growth. The Eucalyptus grandis seedlings were grown in a greenhouse, inoculated or not with the isolated ectomycorrhizal Pisolithus microcarpus (UFSC-Pt116), produced in peat or Entisol. After 120 days, the seedlings were transplanted to an area subject to the sandy process, in the São Francisco de Assis city, RS. The plants have been evaluated regarding survival, height, stem diameter, nitrogen, phosphorus and potassium levels and total phosphorus, inorganic phosphorus, organic phosphorus and wood production on different days after planting. The seedlings grown on the Entisol which was inoculated with the isolated UFSC-Pt116 presented higher survival rates, height, stem diameter, nitrogen concentration and wood production then non-inoculated seedlings. Inoculation with ectomycorrhizal fungi enhanced the production of E. grandis seedlings in survival rates, height, stem diameter. PMID:25763017

Harvesting Productionin Uneven-Aged Loblolly-Shortleaf Pine Stands:The Crossett Farm Forestry Forties

Treesearch

R. Kluender; B. Stokes; S. Woodfin

1992-01-01

Twostands managed using uneven-aged techniques werehar- vested aspar-t of a5-year entry schedule. Felling and skidding productivity varied significantly with average stem diameter and volume and was affected by diameter distribution of the removed material.

Tracheid diameter is the key trait determining the extent of freezing-induced embolism in conifers.

PubMed

Pittermann, Jarmila; Sperry, John

2003-09-01

We tested the hypotheses that freezing-induced embolism is related to conduit diameter, and that conifers and angiosperms with conduits of equivalent diameter will exhibit similar losses of hydraulic conductivity in response to freezing. We surveyed the freeze-thaw response of conifers with a broad range of tracheid diameters by subjecting wood segments (root, stem and trunk wood) to a freeze-thaw cycle at -0.5 MPa in a centrifuge. Embolism increased as mean tracheid diameter exceeded 30 microm. Tracheids with a critical diameter greater than 43 microm were calculated to embolize in response to freezing and thawing at a xylem pressure of -0.5 MPa. To confirm that freezing-induced embolism is a function of conduit air content, we air-saturated stems of Abies lasiocarpa (Hook.) Nutt. (mean conduit diameter 13.7 +/- 0.7 microm) by pressurizing them 1 to 60 times above atmospheric pressure, prior to freezing and thawing. The air saturation method simulated the effect of increased tracheid size because the degree of super-saturation is proportional to a tracheid volume holding an equivalent amount of dissolved air at ambient pressure. Embolism increased when the dissolved air content was equivalent to a mean tracheid diameter of 30 microm at ambient air pressure. Our centrifuge and air-saturation data show that conifers are as vulnerable to freeze-thaw embolism as angiosperms with equal conduit diameter. We suggest that the hydraulic conductivity of conifer wood is maximized by increasing tracheid diameters in locations where freezing is rare. Conversely, the narrowing of tracheid diameters protects against freezing-induced embolism in cold climates.

Incorporating additional tree and environmental variables in a lodgepole pine stem profile model

Treesearch

John C. Byrne

1993-01-01

A new variable-form segmented stem profile model is developed for lodgepole pine (Pinus contorta) trees from the northern Rocky Mountains of the United States. I improved estimates of stem diameter by predicting two of the model coefficients with linear equations using a measure of tree form, defined as a ratio of dbh and total height. Additional improvements were...

A comparison of two stem injection treatments applied to American beech in central West Virginia

Treesearch

Jeffrey D. Kochenderfer; Gary W. Miller; James N. Kochenderfer

2012-01-01

Efficacies for two herbicide stem injection treatments on American beech (Fagus grandifolia Ehrh.) and impacts to nontarget residual trees were evaluated in central West Virginia. The treatments consisted of hack-and-squirt injection of all beech stems ≥1.0 in. to 9.9 in. diameter at breast height (d.b.h.) with either imazapyr as Arsenal...

Styrax americanus Lam.

Treesearch

K.F Connor

2004-01-01

American snowbell, also known as mock orange or storax, is a deciduous shrub or small tree with a widely branched crown. It reaches 3 to 5 m in height, and the stems can reach 7.5 cm in diameter. While the bark on the stems is smooth and dark grey to brown, branches range in color from green to grey to red-brown. Young stems are pubescent, becoming glabrous with age....

Interspecific divergence in foliar nutrient dynamics and stem growth in a temperate forest in response to chronic nitrogen inputs

Treesearch

Jeffrey D. May; Sarah Beth Burdette; Frank S. Gilliam; Mary Beth Adams

2005-01-01

We studied the effects of excessive nitrogen (N) fertilization on foliar nutrient dynamics and stem growth in three important tree species in a mixed-deciduous forest. Stem diameter growth, foliar N concentrations, nitrogen-phosphorus (NIP) ratios, and nutrient resorption were determined for Acer rubrum L. (ACRU), Liriodendron tulipifera L. (LITU), and Prunas serotina...

Tolerance of Loblolly Pines to Fusiform Rust

Treesearch

Charles H. Walkinshaw; James P. Barnett

1995-01-01

Loblolly pines (Pinus taeda L.) that were 8 to 17 yr old tolerated one to three fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) galls in their stems.Families with four or more galls in their stems lost 2.5% or more of the trees by age 17.In living trees with less than four stem galls, diameter growth was comparable to...

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited

PubMed Central

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as ‘Milton’s Law of resource availability and allocation,’ have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for ‘Milton’s Law,’ since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning. PMID:25870769

Models of knot and stem development in black spruce trees indicate a shift in allocation priority to branches when growth is limited.

PubMed

Duchateau, Emmanuel; Auty, David; Mothe, Frédéric; Longuetaud, Fleur; Ung, Chhun Huor; Achim, Alexis

2015-01-01

The branch autonomy principle, which states that the growth of individual branches can be predicted from their morphology and position in the forest canopy irrespective of the characteristics of the tree, has been used to simplify models of branch growth in trees. However, observed changes in allocation priority within trees towards branches growing in light-favoured conditions, referred to as 'Milton's Law of resource availability and allocation,' have raised questions about the applicability of the branch autonomy principle. We present models linking knot ontogeny to the secondary growth of the main stem in black spruce (Picea mariana (Mill.) B.S.P.), which were used to assess the patterns of assimilate allocation over time, both within and between trees. Data describing the annual radial growth of 445 stem rings and the three-dimensional shape of 5,377 knots were extracted from optical scans and X-ray computed tomography images taken along the stems of 10 trees. Total knot to stem area increment ratios (KSR) were calculated for each year of growth, and statistical models were developed to describe the annual development of knot diameter and curvature as a function of stem radial increment, total tree height, stem diameter, and the position of knots along an annual growth unit. KSR varied as a function of tree age and of the height to diameter ratio of the stem, a variable indicative of the competitive status of the tree. Simulations of the development of an individual knot showed that an increase in the stem radial growth rate was associated with an increase in the initial growth of the knot, but also with a shorter lifespan. Our results provide support for 'Milton's Law,' since they indicate that allocation priority is given to locations where the potential return is the highest. The developed models provided realistic simulations of knot morphology within trees, which could be integrated into a functional-structural model of tree growth and above-ground resource partitioning.

Stem extension and mechanical stability of Xanthium canadense grown in an open or in a dense stand

PubMed Central

Watari, Ryoji; Nagashima, Hisae; Hirose, Tadaki

2014-01-01

Background and Aims Plants in open, uncrowded habitats typically have relatively short stems with many branches, whereas plants in crowded habitats grow taller and more slender at the expense of mechanical stability. There seems to be a trade-off between height growth and mechanical stability, and this study addresses how stand density influences stem extension and consequently plant safety margins against mechanical failure. Methods Xanthium canadense plants were grown either solitarily (S-plants) or in a dense stand (D-plants) until flowering. Internode dimensions and mechanical properties were measured at the metamer level, and the critical buckling height beyond which the plant elastically buckles under its own weight and the maximum lateral wind force the plant can withstand were calculated. Key Results Internodes were longer in D- than S-plants, but basal diameter did not differ significantly. Relative growth rates of internode length and diameter were negatively correlated to the volumetric solid fraction of the internode. Internode dry mass density was higher in S- than D-plants. Young's modulus of elasticity and the breaking stress were higher in lower metamers, and in D- than in S-plants. Within a stand, however, both moduli were positively related to dry mass density. The buckling safety factor, a ratio of critical buckling height to actual height, was higher in S- than in D-plants. D-plants were found to be approaching the limiting value 1. Lateral wind force resistance was higher in S- than in D-plants, and increased with growth in S-plants. Conclusions Critical buckling height increased with height growth due mainly to an increase in stem stiffness and diameter and a reduction in crown/stem mass ratio. Lateral wind force resistance was enhanced due to increased tissue strength and diameter. The increase in tissue stiffness and strength with height growth plays a crucial role in maintaining a safety margin against mechanical failure in herbaceous species that lack the capacity for secondary growth. PMID:24879768

Water transport through tall trees: A vertically-explicit, analytical model of xylem hydraulic conductance in stems.

PubMed

Couvreur, Valentin; Ledder, Glenn; Manzoni, Stefano; Way, Danielle A; Muller, Erik B; Russo, Sabrina E

2018-05-08

Trees grow by vertically extending their stems, so accurate stem hydraulic models are fundamental to understanding the hydraulic challenges faced by tall trees. Using a literature survey, we showed that many tree species exhibit continuous vertical variation in hydraulic traits. To examine the effects of this variation on hydraulic function, we developed a spatially-explicit, analytical water transport model for stems. Our model allows Huber ratio, stem-saturated conductivity, pressure at 50% loss of conductivity, leaf area, and transpiration rate to vary continuously along the hydraulic path. Predictions from our model differ from a matric flux potential model parameterized with uniform traits. Analyses show that cavitation is a whole-stem emergent property resulting from nonlinear pressure-conductivity feedbacks that, with gravity, cause impaired water transport to accumulate along the path. Because of the compounding effects of vertical trait variation on hydraulic function, growing proportionally more sapwood and building tapered xylem with height, as well as reducing xylem vulnerability only at branch tips while maintaining transport capacity at the stem base, can compensate for these effects. We therefore conclude that the adaptive significance of vertical variation in stem hydraulic traits is to allow trees to grow tall and tolerate operating near their hydraulic limits. This article is protected by copyright. All rights reserved.

Traits and trade-offs in whole-tree hydraulic architecture along the vertical axis of Eucalyptus grandis.

PubMed

Pfautsch, Sebastian; Aspinwall, Michael J; Drake, John E; Chacon-Doria, Larissa; Langelaan, Rob J A; Tissue, David T; Tjoelker, Mark G; Lens, Frederic

2018-01-25

Sapwood traits like vessel diameter and intervessel pit characteristics play key roles in maintaining hydraulic integrity of trees. Surprisingly little is known about how sapwood traits covary with tree height and how such trait-based variation could affect the efficiency of water transport in tall trees. This study presents a detailed analysis of structural and functional traits along the vertical axes of tall Eucalyptus grandis trees. To assess a wide range of anatomical and physiological traits, light and electron microscopy was used, as well as field measurements of tree architecture, water use, stem water potential and leaf area distribution. Strong apical dominance of water transport resulted in increased volumetric water supply per unit leaf area with tree height. This was realized by continued narrowing (from 250 to 20 µm) and an exponential increase in frequency (from 600 to 13 000 cm-2) of vessels towards the apex. The widest vessels were detected at least 4 m above the stem base, where they were associated with the thickest intervessel pit membranes. In addition, this study established the lower limit of pit membrane thickness in tall E. grandis at ~375 nm. This minimum thickness was maintained over a large distance in the upper stem, where vessel diameters continued to narrow. The analyses of xylem ultrastructure revealed complex, synchronized trait covariation and trade-offs with increasing height in E. grandis. Anatomical traits related to xylem vessels and those related to architecture of pit membranes were found to increase efficiency and apical dominance of water transport. This study underlines the importance of studying tree hydraulic functioning at organismal scale. Results presented here will improve understanding height-dependent structure-function patterns in tall trees. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Estimating past diameters of ponderosa pine in northern California

Treesearch

Robert F. Powers

1969-01-01

Past outside bark diameters (d.o.b.) of ponderosa pine in northern California can be estimated from the relation of bark thickness to stem diameter. An equation for estimating past d.o.b.'s has been developed. The relationship appears to be linear between 1 and 20 inches d.o.b. and differs from ratios reported for the species in other areas. Site quality and crown...

Height-diameter equations for young-growth red fir in California and southern Oregon

Treesearch

K. Leroy Dolph

1989-01-01

Total tree height of young-growth red fir can be estimated from the relation of total tree height to diameter outside bark at breast height (DOB). Total tree heights and corresponding diameters were obtained from stem analyses of 562 trees distributed across 56 sampling locations in the true fir forest type of California and Oregon. The resulting equations can predict...

Biomass of singleleaf pinyon and Utah juniper

Treesearch

E. L. Miller; R. O. Meeuwig; J. D. Budy

1981-01-01

Biomass determinations in singleleaf pinyon (Pinus monophylla) - Utah juniper (Juniperus osteosperma) stands in Nevada indicate that stem diameter and average crown diameter are the tree measurements most highly correlated with ovendry weights. The equations and tables developed provide a means for estimating the total aboveground...

Seasonal dynamics of radial growth and stem water deficit in co-occurring saplings and mature conifers under drought: Canopy density affects water stress experienced by saplings

NASA Astrophysics Data System (ADS)

Oberhuber, Walter

2017-04-01

Size-mediated climate sensitivity of trees will affect forest structure, composition and productivity under a warmer and drier climate. Therefore, the influence of tree size (saplings vs. mature trees) and site conditions on radial stem growth and stem water deficit of Picea abies (dry-mesic site; canopy cover [CC]: 70 %) and Pinus sylvestris (xeric site; CC: 30 %) were evaluated in a drought-prone inner Alpine environment (c. 750 m a.s.l.). Stem radius variations (SRVs) of saplings (mean stem diameter [SDM]: 2.3 cm) and co-occurring mature trees (SDM: 24 cm) were continuously recorded by dendrometers during two years (n = 6 - 8 individuals per species and size class). Growth-detrended SRVs (SSRV), which represent reversible shrinkage and swelling of tissues outside the cambium and contribute most to stem water storage capacity, were calculated by removing the Gompertz-modeled daily growth from SRVs. Dendrometer records revealed that irrespective of tree size, radial growth in Pinus sylvestris occurred in April-May, whereas the main growing period of Picea abies was April-June and May-June in saplings and mature trees, respectively. Growth-detrended SRVs were approximately twice as large in Pinus sylvestris compared to Picea abies indicating more intense exploitation of stem water reserves at the xeric site. Linear relationships between SSRVs of mature trees vs. saplings and climate-SSRV relationships revealed greater use of stem water reserves by mature Picea abies compared to saplings. This suggests that the strikingly depressed radial growth of Picea abies saplings was primarily caused by reduced carbon availability beneath the dense canopy. In contrast, a tree size effect on the seasonal dynamics of radial growth, stem water deficit and climate-SSRV relationships was mostly lacking in Pinus sylvestris, indicating comparable water status in mature trees and saplings under an open canopy. Results of this study provide evidence that development of a buffered microclimate under dense canopy mitigates water stress experienced by saplings and favors tree recruitment at drought-prone sites. This study was funded by the Austrian Science Fund (FWF): P25643-B16 "Carbon allocation and growth of Scots pine".

Core drill's bit is replaceable without withdrawal of drill stem - A concept

NASA Technical Reports Server (NTRS)

Rushing, F. C.; Simon, A. B.

1970-01-01

Drill bit is divided into several sectors. When collapsed, the outside diameter is forced down the drill stem, when it reaches bottom the sectors are forced outward and form a cutting bit. A dulled bit is retracted by reversal of this procedure.

[Effects of Cuscuta australis parasitism on the growth, reproduction and defense of Solidago canadensis].

PubMed

Yang, Bei-fen; Du, Le-shan; Li, Jun-min

2015-11-01

In order to find out how parasitic Cuscuta australis influences the growth and reproduction of Solidago canadensis, the effects of the parasitism of C. australis on the morphological, growth and reproductive traits of S. canadensis were examined and the relationships between the biomass and the contents of the secondary metabolites were analyzed. The results showed that the parasitism significantly reduced the plant height, basal diameter, root length, root diameter, root biomass, stem biomass, leaf biomass, total biomass, number of inflorescences branches, axis length of inflorescence, and number of inflorescence. In particular, plant height, number of inflorescence and the stem biomass of parasitized S. canadensis were only 1/2, 1/5 and 1/8 of non-parasitized plants, respectively. There was no significant difference of plant height, root length, stem biomass and total biomass between plants parasitized with high and low intensities. But the basal diameter, root volume, leaf biomass, root biomass, the number of inflorescences branches, axis length of inflorescence and number of inflorescence of S. canadensis parasitized with high intensity were significantly lower than those of plants parasitized with low intensity. The parasitism of C. australis significantly increased the tannins content in the root and the flavonoids content in the stem of S. canadensis. The biomass of S. canadensis was significantly negatively correlated with the tannin content in the root and the flavonoids content in the stem. These results indicated that the parasitism of C. australis could inhibit the growth of S. canadensis by changing the resources allocation patterns as well as reducing the resources obtained by S. canadensis.

Variation of the pressure limits of flame propagation with tube diameter for propane-air mixtures

NASA Technical Reports Server (NTRS)

Belles, Frank E; Simon, Dorothy M

1951-01-01

An investigation was made of the variation of the pressure limits of flame propagation with tube diameter for quiescent propane with tube diameter for quiescent propane-air mixtures. Pressure limits were measured in glass tubes of six different inside diameters, with a precise apparatus. Critical diameters for flame propagation were calculated and the effect of pressure was determined. The critical diameters depended on the pressure to the -0.97 power for stoichiometric mixtures. The pressure dependence decreased with decreasing propane concentration. Critical diameters were related to quenching distance, flame speeds, and minimum ignition energy.

Morphology, surface temperatures, and northern limits of columnar cacti in the Sonoran Desert

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nobel, P.S.

1980-02-01

Interspecific morphological differences and intraspecific morphological changes with latitude were evaluated to help examine the distributional ranges of Carnegiea gigantea, Lemaireocereus thurberi, Lophocereus schottii, Pachycereus pecten-aboriginum, and P. pringlei in the Sonoran Desert (US and Mexico). A computer model, which predicted the average surface temperature of the stem within 1/sup 0/C of that measured hourly throughout a 24-h period, was particularly useful in studying the thermal relations of the stem apex, where the lowest surface temperature occurred. Simulated increases in stem diameter raised the minimum apical temperature for C. gigantea and may help account for the extension of its rangemore » to higher latitudes than the other species studied. However, diameter increases led to a slight decrease in minimum apical temperatures for Lophocereus schottii. The immature stems of L. schottii are morphologically distinct from the mature stems, which caused minimum apical temperatures to be 1.6/sup 0/C lower for the immature stems under given environmental conditions; thus, freezing damage to the immature stems could limit the northward extension of the range of this species. As the apical pubescence in the simulations was increased up to the normal amount (10 mm), the minimum apical temperature for the stem of C. gigantea increased 2.4/sup 0/C. Simulated increases in spine shading of the apexalso raised the minimum apical temperatures, again indicating the influence of morphological features on the temperature of the meristematic region.« less

Genetic evaluation of Jatropha curcas: an important oilseed for biodiesel production.

PubMed

Freitas, R G; Missio, R F; Matos, F S; Resende, M D V; Dias, L A S

2011-01-01

Jatropha curcas, internationally and locally known, respectively, as physic nut and pinhão manso, is a highly promising species for biodiesel production in Brazil and other countries in the tropics. It is rustic, grows in warm regions and is easily cultivated. These characteristics and high-quality oil yields from the seeds have made this plant a priority for biodiesel programs in Brazil. Consequently, this species merits genetic investigations aimed at improving yields. Some studies have detected genetic variability in accessions in Africa and Asia. We have made the first genetic evaluation of J. curcas collected from Brazil. Our objective was to quantify genetic diversity and to estimate genetic parameters for growth and production traits and seed oil content. We evaluated 75 J. curcas progenies collected from Brazil and three from Cambodia. The mean oil content in the seeds was 31%, ranging from 16 to 45%. No genetic correlation between growth traits and seed oil content was found. However, high coefficients of genetic variation were found for plant height, number of branches, height of branches, and stem diameter. The highest individual narrow-sense heritabilities were found for leaf length (0.35) and width (0.34), stem diameter (0.24) and height of branches (0.21). We used a clustering algorithm to genetically identify the closest and most distant progenies, to assist in the development of new cultivars. Geographical diversity did not necessarily represent the genetic diversity among the accessions collected. These results are important for the continuity of breeding programs, aimed at obtaining cultivars with high grain yield and high oil content in seeds.

The Sap Flow Dynamics and Response of Hedysarum scoparium to Environmental Factors in Semiarid Northwestern China.

PubMed

Deng, Jifeng; Ding, Guodong; Gao, Guanglei; Wu, Bin; Zhang, Yuqing; Qin, Shugao; Fan, Wenhui

2015-01-01

Hedysarum scoparium is an important, fast-growing and drought-resistant shrub that has been extensively used for grassland restoration and preventing desertification in semiarid regions of northwestern China. The primary objective of this study was to investigate the diurnal and seasonal variations in stem sap flow (Js) and its relation to environmental factors. The stem heat balance method was applied to plants that were approximately 17 years old (with diameters of 25, 16, 13, and 9 mm at ground level and heights of 3.1, 1.8, 1.7 and 1.4 m) and growing under natural conditions. The vertical soil temperature profile (ST), soil surface heat flux (SoilG), volumetric soil moisture content (SWC) and meteorological variables such as solar radiation (Rn), air temperature (Ta), vapour pressure deficit (VPD), wind speed (Ws) relative humidity (RH) and precipitation (P) were simultaneously measured at a meteorological station on site. Results indicated that Js varied regularly during the diurnal and seasonal term. The nocturnal Js was substantial, with a seasonal variation similar to the patterns of daytime Js. The magnitude of Js changed considerably between sunny and rainy days. Redundancy (RDA) and Kendall's tau analysis suggested that daily Js in large plants was more sensitive to environmental factors, and the variation in daily Js during the growing season could be described by a multiple linear regression against environmental variables including Ta, VPD, Ws, RH, ST, and SoilG. While the nocturnal Js in smaller plants was more sensitive to meteorological factors. Ta, VPD, and Ws were significantly correlated with nighttime Js. The hourly nighttime sap flow rate of H. scoparium corresponded closely to Ta and VPD following a non-linear pattern. The results of this study can be used to estimate the transpiration of H. scoparium.

[Spatial variation in diurnal courses of stem temperature of Betula platyphylla and Fraxinus mandshurica and its influencing factors].

PubMed

Li, Yu Ran; Wang, Xing Chang; Wang, Chuan Kuan; Liu, Fan; Zhang, Quan Zhi

2017-10-01

Plant temperature is an important parameter for estimating energy balance and vegetation respiration of forest ecosystem. To examine spatial variation in diurnal courses of stem temperatures (T s ) and its influencing factors, we measured the T s with copper constantan thermocouples at different depths, heights and azimuths within the stems of two broadleaved tree species with contrasting bark and wood properties, Betula platyphylla and Fraxinus mandshurica. The results showed that the monthly mean diurnal courses of the T s largely followed that of air temperature with a 'sinusoi dal' pattern, but the T s lagged behind the air temperature by 0 h at the stem surface to 4 h at 6 cm depth. The daily maximal values and ranges of the diurnal course of T s decreased gradually with increasing measuring depth across the stem and decreasing measuring height along the stem. The circumferential variation in T s was marginal, with slightly higher daily maximal values in the south and west directions during the daytime of the dormant season. Differences in thermal properties (i.e. , specific heat capacity and thermal conductivity) of both bark and wood tissue between the two species contributed to the inter specific variations in the radial variation in T s through influencing the heat exchange between the stem surface and ambient air as well as heat diffusion within the stem. The higher reflectance of the bark of B. platyphylla decreased the influence of solar radiation on T s . The stepwise regression showed that the diurnal courses of T s could be well predicted by the environmental factors (R 2 > 0.85) with an order of influence ranking as air temperature > water vapor pressure > net radiation > wind speed. It is necessary to take the radial, vertical and inter specific varia-tions in T s into account when estimating biomass heat storage and stem CO2 efflux.

Quantitative Evaluation of Brain Stem Atrophy Using Magnetic Resonance Imaging in Adult Patients with Alexander Disease.

PubMed

Yoshida, Tomokatsu; Yasuda, Rei; Mizuta, Ikuko; Nakagawa, Masanori; Mizuno, Toshiki

2017-01-01

Brain MRI in adult patients with Alexander disease (AxD) mainly shows atrophy in the medulla oblongata. However, currently there is no quantitative standard for assessing this atrophy. In this study, we quantitatively evaluated the brain stem of AxD patients with glial fibrillary acidic protein (GFAP) mutation using conventional MRI to evaluate its usefulness as an aid to diagnosing AxD in daily clinical practice. Nineteen AxD patients with GFAP mutation were compared with 14 patients negative for GFAP mutation in whom AxD was suspected due to "atrophy of the medulla oblongata." In the GFAP mutation-positive group, the sagittal diameter of the medulla oblongata, the ratio of the diameter of the medulla oblongata to that of the midbrain (MO/MB), and the ratio of the sagittal diameter of the medulla oblongata to that of the pons (MO/Po) were significantly smaller compared to those of the GFAP mutation-negative group (p < 0.01). The sensitivity and specificity of each parameter were 87.5 and 92.3%, 91.7 and 81.3%, and 88.2 and 100% with a sagittal diameter of the medulla oblongata <9.0 mm, MO/MB <0.60, and sagittal MO/Po <0.46, respectively. These parameters can provide very useful information to differentially diagnose AxD from other disorders associated with brain stem atrophy in adult patients. © 2017 S. Karger AG, Basel.

Influence of sewage sludge, as a substrate, in the plasticity of functional characteristics of plants.

PubMed

da Silva, Vicente Elício Porfiro Sales Gonçalves; Buarque, Patrícia Marques Carneiro; Ferreira, Wanessa Nepomuceno; Buarque, Hugo Leonardo de Brito; Silva, Maria Amanda Menezes

2018-04-24

This work aimed to evaluate the effect of sewage sludge application as fertilizer on the plasticity of functional characteristics of species commonly found in the Caatinga. The research was developed in the nursery of the Federal Institute of Education, Science and Technology of Ceará (IFCE), Quixadá campus, located in northeastern Brazil. Three treatments were applied: raw sludge, sanitized sludge, and no manipulation. In each treatment, five species were planted, each with five individuals, totaling 75 individuals, which were tagged, and 4 months after germination, they were destroyed to obtain dry matter content (TMSF) from leaf, stem (TMSC), fine root (TMSRF), and thick root (TMSRG); leaf area; height and diameter of the seedling; and length above and below the ground. The sanitized sludge was responsible for giving higher values for leaf area, height of the seedlings, and diameter and length of stem and root. However, the dry matter content of the fine roots was higher in the treatment without manipulation. At the community level, as TMSRG increased, TMSC also increased, the same occurred between TMSRG and TMSRF, TMSC and TMSRF, and stem length and leaf area. In the treatment without manipulation, there was a positive correlation between leaf area, height and plant diameter, and negative correlation between root length and plant diameter. Thus, it can be concluded that the use of sanitized sludge is a good tool to increase the availability of soil resources, conferring to individuals' greater dry matter content, greater leaf area, and higher height and diameter above the ground.

Disturbances of stem circumnutations evoked by wound-induced variation potentials in Helianthus annuus L.

PubMed

Stolarz, Maria; Dziubińska, Halina; Krupa, Maciej; Buda, Agnieszka; Trebacz, Kazimierz; Zawadzki, Tadeusz

2003-01-01

The relationship between evoked electrical activity and stem movements in three-week old sunflowers was demonstrated. Electrical potential changes (recorded by Ag/AgCl extracellular electrodes) and time-lapse images (from a top view camera) were recorded and analyzed. A heat stimulus applied to the tip of one of the second pair of leaves evoked a variation potential, transmitted basipetally along one side of the stem. After stimulation, disturbances of circumnutations occurred. They included: changes in the period, disorders in the elliptical shape, and, in some cases, reversion of direction (of movement). We suggest that asymmetrically propagated variation potential induces asymmetric stem shrinking and bending, which strongly disturbs circumnutations. Our results confirm the involvement of electrical potential changes in the mechanism of stem nutations.

Early radiological and functional outcomes for a cementless press-fit design modular femoral stem revision system.

PubMed

Hancock, Douglas S; Sharplin, Paul K; Larsen, Peter D; Phillips, Fredrick Ts

2018-05-01

To assess early radiological and functional outcomes of revision hip surgery with a cementless press-fit design femoral stem. A retrospective review of 48 consecutive revision total hip replacements using the RECLAIM revision hip system, between October 2012 and August 2015. Radiographic assessment was undertaken with serial anteroposterior (AP) X-rays of the pelvis. Risk factors for subsidence were evaluated. Prospective clinical follow up was performed on 21 patients to assess functional outcomes. Mean stem subsidence was 1.1 mm (95% confidence interval[CI]: 0.63-1.57). Median follow up of 12 months. An inverse relationship was observed between level of subsidence and femoral stem diameter r = -0.45, p = 0.001. Subsidence at the time of follow-up assessment was correlated with initial subsidence (correlation coefficient rho 0.69, p = 0.001). The mean Merle d'Aubigne score at the latest follow up was 14.2 (range 8-17). The mean OHS was 34.1 (range 15-48). Early radiological and functional outcomes for the RECLAIM revision system showed very low levels of subsidence and good functional outcomes. There was an association with smaller diameter femoral stems and greater levels of subsidence.

7 CFR 51.320 - Diameter.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined by...

7 CFR 51.320 - Diameter.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined by...

7 CFR 51.320 - Diameter.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined by...

Contrasting submergence tolerance in two species of stem-succulent halophytes is not determined by differences in stem internal oxygen dynamics.

PubMed

Konnerup, Dennis; Moir-Barnetson, Louis; Pedersen, Ole; Veneklaas, Erik J; Colmer, Timothy D

2015-02-01

Many stem-succulent halophytes experience regular or episodic flooding events, which may compromise gas exchange and reduce survival rates. This study assesses submergence tolerance, gas exchange and tissue oxygen (O2) status of two stem-succulent halophytes with different stem diameters and from different elevations of an inland marsh. Responses to complete submergence in terms of stem internal O2 dynamics, photosynthesis and respiration were studied for the two halophytic stem-succulents Tecticornia auriculata and T. medusa. Plants were submerged in a glasshouse experiment for 3, 6 and 12 d and O2 levels within stems were measured with microelectrodes. Photosynthesis by stems in air after de-submergence was also measured. Tecticornia medusa showed 100 % survival in all submergence durations whereas T. auriculata did not survive longer than 6 d of submergence. O2 profiles and time traces showed that when submerged in water at air-equilibrium, the thicker stems of T. medusa were severely hypoxic (close to anoxic) when in darkness, whereas the smaller diameter stems of T. auriculata were moderately hypoxic. During light periods, underwater photosynthesis increased the internal O2 concentrations in the succulent stems of both species. Stems of T. auriculata temporally retained a gas film when first submerged, whereas T. medusa did not. The lower O2 in T. medusa than in T. auriculata when submerged in darkness was largely attributed to a less permeable epidermis. The submergence sensitivity of T. auriculata was associated with swelling and rupturing of the succulent stem tissues, which did not occur in T. medusa. The higher submergence tolerance of T. medusa was not associated with better internal aeration of stems. Rather, this species has poor internal aeration of the succulent stems due to its less permeable epidermis; the low epidermal permeability might be related to resistance to swelling of succulent stem tissues when submerged. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ethnic variation in gender-STEM stereotypes and STEM participation: an intersectional approach.

PubMed

O'Brien, Laurie T; Blodorn, Alison; Adams, Glenn; Garcia, Donna M; Hammer, Elliott

2015-04-01

Stereotypes associating men and masculine traits with science, technology, engineering, and mathematics (STEM) fields are ubiquitous, but the relative strength of these stereotypes varies considerably across cultures. The present research applies an intersectional approach to understanding ethnic variation in gender-STEM stereotypes and STEM participation within an American university context. African American college women participated in STEM majors at higher rates than European American college women (Study 1, Study 2, and Study 4). Furthermore, African American women had weaker implicit gender-STEM stereotypes than European American women (Studies 2-4), and ethnic differences in implicit gender-STEM stereotypes partially mediated ethnic differences in STEM participation (Study 2 and Study 4). Although African American men had weaker implicit gender-STEM stereotypes than European American men (Study 4), ethnic differences between men in STEM participation were generally small (Study 1) or nonsignificant (Study 4). We discuss the implications of an intersectional approach for understanding the relationship between gender and STEM participation. (c) 2015 APA, all rights reserved).

Influence of tree size, taxonomy, and edaphic conditions on heart rot in mixed-dipterocarp Bornean rainforests: implications for aboveground biomass estimates

NASA Astrophysics Data System (ADS)

Heineman, K. D.; Russo, S. E.; Baillie, I. C.; Mamit, J. D.; Chai, P. P.-K.; Chai, L.; Hindley, E. W.; Lau, B.-T.; Tan, S.; Ashton, P. S.

2015-05-01

Fungal decay of heartwood creates hollows and areas of reduced wood density within the stems of living trees known as heart rot. Although heart rot is acknowledged as a source of error in forest aboveground biomass estimates, there are few datasets available to evaluate the environmental controls over heart rot infection and severity in tropical forests. Using legacy and recent data from drilled, felled, and cored stems in mixed dipterocarp forests in Sarawak, Malaysian Borneo, we quantified the frequency and severity of heart rot, and used generalized linear mixed effect models to characterize the association of heart rot with tree size, wood density, taxonomy, and edaphic conditions. Heart rot was detected in 55% of felled stems > 30 cm DBH, while the detection frequency was lower for stems of the same size evaluated by non-destructive drilling (45%) and coring (23%) methods. Heart rot severity, defined as the percent stem volume lost in infected stems, ranged widely from 0.1-82.8%. Tree taxonomy explained the greatest proportion of variance in heart rot frequency and severity among the fixed and random effects evaluated in our models. Heart rot frequency, but not severity, increased sharply with tree diameter, ranging from 56% infection across all datasets in stems > 50 cm DBH to 11% in trees 10-30 cm DBH. The frequency and severity of heart rot increased significantly in soils with low pH and cation concentrations in topsoil, and heart rot was more common in tree species associated with dystrophic sandy soils than with nutrient-rich clays. When scaled to forest stands, the percent of stem biomass lost to heart rot varied significantly with soil properties, and we estimate that 7% of the forest biomass is in some stage of heart rot decay. This study demonstrates not only that heart rot is a significant source of error in forest carbon estimates, but also that it strongly covaries with soil resources, underscoring the need to account for edaphic variation in estimating carbon storage in tropical forests.

Baseline study of morphometric traits of wild Capsicum annuum growing near two biosphere reserves in the Peninsula of Baja California for future conservation management.

PubMed

Murillo-Amador, Bernardo; Rueda-Puente, Edgar Omar; Troyo-Diéguez, Enrique; Córdoba-Matson, Miguel Víctor; Hernández-Montiel, Luis Guillermo; Nieto-Garibay, Alejandra

2015-05-10

Despite the ecological and socioeconomic importance of wild Capsicum annuum L., few investigations have been carried out to study basic characteristics. The peninsula of Baja California has a unique characteristic that it provides a high degree of isolation for the development of unique highly diverse endemic populations. The objective of this study was to evaluate for the first time the growth type, associated vegetation, morphometric traits in plants, in fruits and mineral content of roots, stems and leaves of three wild populations of Capsicum in Baja California, Mexico, near biosphere reserves. The results showed that the majority of plants of wild Capsicum annuum have a shrub growth type and were associated with communities consisting of 43 species of 20 families the most representative being Fabaceae, Cactaceae and Euphorbiaceae. Significant differences between populations were found in plant height, main stem diameter, beginning of canopy, leaf area, leaf average and maximum width, stems and roots dry weights. Coverage, leaf length and dry weight did not show differences. Potassium, sodium and zinc showed significant differences between populations in their roots, stems and leaves, while magnesium and manganese showed significant differences only in roots and stems, iron in stems and leaves, calcium in roots and leaves and phosphorus did not show differences. Average fruit weight, length, 100 fruits dry weight, 100 fruits pulp dry weight and pulp/seeds ratio showed significant differences between populations, while fruit number, average fruit fresh weight, peduncle length, fruit width, seeds per fruit and seed dry weight, did not show differences. We concluded that this study of traits of wild Capsicum, provides useful information of morphometric variation between wild populations that will be of value for future decision processes involved in the management and preservation of germplasm and genetic resources.

Improved attachment of mesenchymal stem cells on super-hydrophobic TiO2 nanotubes.

PubMed

Bauer, Sebastian; Park, Jung; von der Mark, Klaus; Schmuki, Patrik

2008-09-01

Self-organized layers of vertically orientated TiO(2) nanotubes providing defined diameters ranging from 15 up to 100nm were grown on titanium by anodic oxidation. These TiO(2) nanotube layers show super-hydrophilic behavior. After coating TiO(2) nanotube layers with a self-assembled monolayer (octadecylphosphonic acid) they showed a diameter-dependent wetting behavior ranging from hydrophobic (108+/-2 degrees ) up to super-hydrophobic (167+/-2 degrees ). Cell adhesion, spreading and growth of mesenchymal stem cells on the unmodified and modified nanotube layers were investigated and compared. We show that cell adhesion and proliferation are strongly affected in the super-hydrophobic range. Adsorption of extracellular matrix proteins as fibronectin, type I collagen and laminin, as well as bovine serum albumin, on the coated and uncoated surfaces showed a strong influence on wetting behavior and dependence on tube diameter.

Method and device for tensile testing of cable bundles

DOEpatents

Robertson, Lawrence M; Ardelean, Emil V; Goodding, James C; Babuska, Vit

2012-10-16

A standard tensile test device is improved to accurately measure the mechanical properties of stranded cables, ropes, and other composite structures wherein a witness is attached to the top and bottom mounting blocks holding the cable under test. The witness is comprised of two parts: a top and a bottom rod of similar diameter with the bottom rod having a smaller diameter stem on its upper end and the top rod having a hollow opening in its lower end into which the stem fits forming a witness joint. A small gap is present between the top rod and the larger diameter portion of the bottom rod. A standard extensometer is attached to the top and bottom rods of the witness spanning this small witness gap. When a force is applied to separate the mounting blocks, the gap in the witness expands the same length that the entire test specimen is stretched.

WRKY13 acts in stem development in Arabidopsis thaliana.

PubMed

Li, Wei; Tian, Zhaoxia; Yu, Diqiu

2015-07-01

Stems are important for plants to grow erectly. In stems, sclerenchyma cells must develop secondary cell walls to provide plants with physical support. The secondary cell walls are mainly composed of lignin, xylan and cellulose. Deficiency of overall stem development could cause weakened stems. Here we prove that WRKY13 acts in stem development. The wrky13 mutants take on a weaker stem phenotype. The number of sclerenchyma cells, stem diameter and the number of vascular bundles were reduced in wrky13 mutants. Lignin-synthesis-related genes were repressed in wrky13 mutants. Chromatin immunoprecipitation assays proved that WRKY13 could directly bind to the promoter of NST2. Taken together, we proposed that WRKY13 affected the overall development of stem. Identification of the role of WRKY13 may help to resolve agricultural problems caused by weaker stems. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Biomass Estimation for some Shrubs from Northeastern Minnesota

Treesearch

David F. Grigal; Lewis F. Ohmann

1977-01-01

Biomass prediction equations were developed for 23 northeastern Minnesota shrub species. The allowmetric function was used to predict leaf, current annual woody twig, stem, and total woody biomass (dry grass), using stem diameter class estimated to the nearest 0.25 cm class at 15 cm above ground level as the independent variable.

Estimating outside-bark stem volume to any top diameter for ash in Wisconsin

Treesearch

Paul F. Doruska; Timothy D. Hart

2010-01-01

The future of Wisconsin's estimated 742 million ash trees (5 million of which are in urban settings composing 20 percent of Wisconsin's urban forests) is being considered based on the presence of the emerald ash borer. Part of this discussion includes the stem volumes of these ash trees.

Feeling stretched or compressed? The multiple mechanosensitive responses of wood formation to bending.

PubMed

Roignant, Jeanne; Badel, Éric; Leblanc-Fournier, Nathalie; Brunel-Michac, Nicole; Ruelle, Julien; Moulia, Bruno; Decourteix, Mélanie

2018-05-11

Trees constantly experience wind, perceive resulting mechanical cues, and modify their growth and development accordingly. Previous studies have demonstrated that multiple bending treatments trigger ovalization of the stem and the formation of flexure wood in gymnosperms, but ovalization and flexure wood have rarely been studied in angiosperms, and none of the experiments conducted so far has used multidirectional bending treatments at controlled intensities. Assuming that bending involves tensile and compressive strain, we hypothesized that different local strains may generate specific growth and wood differentiation responses. Basal parts of young poplar stems were subjected to multiple transient controlled unidirectional bending treatments during 8 weeks, which enabled a distinction to be made between the wood formed under tensile or compressive flexural strains. This set-up enabled a local analysis of poplar stem responses to multiple stem bending treatments at growth, anatomical, biochemical and molecular levels. In response to multiple unidirectional bending treatments, poplar stems developed significant cross-sectional ovalization. At the tissue level, some aspects of wood differentiation were similarly modulated in the compressed and stretched zones (vessel frequency and diameter of fibres without a G-layer), whereas other anatomical traits (vessel diameter, G-layer formation, diameter of fibres with a G-layer and microfibril angle) and the expression of fasciclin-encoding genes were differentially modulated in the two zones. This work leads us to propose new terminologies to distinguish the 'flexure wood' produced in response to multiple bidirectional bending treatments from wood produced under transient tensile strain (tensile flexure wood; TFW) or under transient compressive strain (compressive flexure wood; CFW). By highlighting similarities and differences between tension wood and TFW and by demonstrating that plants could have the ability to discriminate positive strains from negative strains, this work provides new insight into the mechanisms of mechanosensitivity in plants.

Small-diameter trees used for chemithermomechanical pulps.

Treesearch

Gary C. Myers; R. James Barbour; Said M. Abubakr

1999-01-01

During the course of restoring and maintaining forest ecosystem health and function in the western interior of the United States, many small-diameter stems are removed from densely stocked stands. In general, these materials are considered nonusable or underutilized. Information on the properties of these resources is needed to help managers understand when timber...

Biomass utilization for bioenergy in the Western United States

Treesearch

D.L. Nicholls; R. Monserud; D. Dykstra

2008-01-01

Wildfires, hazardous fuel buildups, small-diameter timber, wildland-urban interface zones, biomass. These are some of the terms becoming familiar to communities throughout the Western United States after the record-breaking fire seasons of the past decade. Although small-diameter stems are generally expensive to remove and often have limited utilization options, the...

Individual tree diameter, height, and volume functions for longleaf pine

Treesearch

Carlos A. Gonzalez-Benecke; Salvador A. Gezan; Timothy A. Martin; Wendell P. Cropper; Lisa J. Samuelson; Daniel J. Leduc

2014-01-01

Currently, little information is available to estimate individual tree attributes for longleaf pine (Pinus palustris Mill.), an important tree species of the southeastern United States. The majority of available models are local, relying on stem diameter outside bark at breast height (dbh, cm) and not including stand-level parameters. We developed...

Multiparameter double hole contrast detail phantom: Ability to detect image displacement due to off position anode stem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pauzi, Nur Farahana; Majid, Zafri Azran Abdul; Sapuan, Abdul Halim

Contrast Detail phantom is a quality control tool to analyze the performance of imaging devices. Currently, its function is solely to evaluate the contrast detail characteristic of imaging system. It consists of drilled hole which gives effect to the penetration of x-ray beam divergence to pass through the base of each hole. This effect will lead to false appearance of image from its original location but it does not being visualized in the radiograph. In this study, a new design of Contrast Detail phantom’s hole which consists of double hole construction has been developed. It can detect the image displacementmore » which is due to off position of anode stem from its original location. The double hole differs from previous milled hole, whereby it consists of combination of different hole diameters. Small hole diameter (3 mm) is positioned on top of larger hole diameter (10 mm). The thickness of double hole acrylic blocks is 13 mm. Result revealed that Multiparameter Double Hole Contrast Detail phantom can visualize the shifted flaw image quality produced by x-ray machine due to improper position of the anode stem which is attached to rotor and stator. The effective focal spot of x-ray beam also has been shifted from the center of collimator as a result of off-position anode stem. As a conclusion, the new design of double hole Contrast Detail phantom able to measure those parameters in a well manner.« less

The hydraulic architecture of Juniperus communis L. ssp. communis: shrubs and trees compared.

PubMed

Beikircher, Barbara; Mayr, Stefan

2008-11-01

Juniperus communis ssp. communis can grow like a shrub or it can develop a tree-like habit. In this study, the hydraulic architecture of these contrasting growth forms was compared. We analysed the hydraulic efficiency (leaf-specific conductivity, k(l); specific conductivity, k(s); Huber value, HV) and the vulnerability to cavitation (the water potential corresponding to a 50% loss of conductivity, Psi(50)), as well as anatomical parameters [mean tracheid diameter, d; mean hydraulic diameter, d(h); cell wall reinforcement (t/b)(h)(2)] of shrub shoots, tree stems and tree branches. Shrub shoots were similar to tree branches (especially to lower branches) in growth form and conductivity (k(l) = 1.93 +/- 0.11 m(2) s(-1) MPa(-1) 10(-7), k(s) = 5.71 +/- 0.19 m(2) s(-1) MPa(-1) 10(-4)), but were similar to tree stems in their vulnerability to cavitation (Psi(50) = -5.81 +/- 0.08 MPa). Tree stems showed extraordinarily high k(l) and k(s) values, and HV increased from the base up. Stem xylem was more vulnerable to cavitation than branch xylem, where Psi(50) increased from lower (Psi(50) = -6.44 +/- 0.19 MPa) to upper branches (Psi(50) = -5.98 +/- 0.13 MPa). Conduit diameters were correlated with k(l) and k(s). Data indicate that differences in hydraulic architecture correspond to changes in growth form. In some aspects, the xylem hydraulics of tree-like Juniperus communis differs from that of other coniferous tree species.

Stem water transport and freeze-thaw xylem embolism in conifers and angiosperms in a Tasmanian treeline heath.

PubMed

Feild, Taylor S; Brodribb, Tim

2001-05-01

The effect of freezing on stem xylem hydraulic conductivity and leaf chlorophyll a fluorescence was measured in 12 tree and shrub species from a treeline heath in Tasmania, Australia. Reduction in stem hydraulic conductivity after a single freeze-thaw cycle was minimal in conifers and the vessel-less angiosperm species Tasmannia lanceolata (Winteraceae), whereas mean loss of conductivity in vessel-forming angiosperms fell in the range 17-83%. A positive linear relationship was observed between percentage loss of hydraulic conductivity by freeze-thaw and the average conduit diameter across all 12 species. This supports the hypothesis that large-diameter vascular conduits have a greater likelihood of freeze-thaw cavitation because larger bubbles are produced, which are more likely to expand under tension. Leaf frost tolerances, as measured by a 50% loss of maximum PSII quantum yield, varied from -6 to -13°C, indicating that these species were more frost-sensitive than plants from northern hemisphere temperate forest and treeline communities. There was no evidence of a relationship between frost tolerance of leaves and the resilience of stem water transport to freezing, suggesting that low temperature survival and the resistance of stem water transport to freezing are independently evolving traits. The results of this study bear on the ecological importance of stem freezing in the southern hemisphere treeline zones.

Ultra-minimally invasive local immune cell therapy and regenerative therapy by multi-piercing surgery for abdominal solid tumor: therapeutic simulation by natural orifice translumenal endoscopic surgery-assisted needlescopic surgery using 3-mm diameter robots.

PubMed

Ohdaira, Takeshi; Tsutsumi, Norifumi; Xu, Hao; Mori, Megumu; Uemura, Munenori; Ieiri, Satoshi; Hashizume, Makoto

2011-07-01

We have invented multi-piercing surgery (MPS) which could potentially solve the triangular formation loss and device clashing which occur in single-port surgery (SPS), as well as restricted visual field, organ damage by needle-type instruments, and impaired removal of a resected organ from the body which occur in needlescopic surgery (NS). MPS is natural orifice translumenal endoscopic surgery (NOTES)-assisted NS. We used 3-mm diameter robots as needle-type instruments for MPS to examine the possibility of local immune cell therapy and regenerative therapy using stem cells for pancreatic cancer. In MPS using two robots, the therapeutic cell suspension was injected into a target region of pancreas in two pigs. Both retention of a capsule of liquid cell suspension and invasive level were evaluated. Triangular formation could be ensured. The use of small-diameter robots allowed (1) the surgical separation of the pancreas and the retroperitoneum, and (2) the formation of the capsule containing the immune cell and stem cell suspension. The endoscope for NOTES provided a clear visual field and also assisted the removal of a resected organ from the body. The visual field of the endoscope could be oriented well by using an electromagnetic navigation system. MPS using small-diameter robots could potentially solve the issues inherent in SPS and NS and could allow minimally invasive local immune cell and stem cell therapy.

Sensitivity analysis of a coupled hydrodynamic-vegetation model using the effectively subsampled quadratures method (ESQM v5.2)

NASA Astrophysics Data System (ADS)

Kalra, Tarandeep S.; Aretxabaleta, Alfredo; Seshadri, Pranay; Ganju, Neil K.; Beudin, Alexis

2017-12-01

Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as the Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant stem density, height, and, to a lesser degree, diameter. Wave dissipation is mostly dependent on the variation in plant stem density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance to optimize efforts and reduce exploration of parameter space for future observational and modeling work.

Stem extension and mechanical stability of Xanthium canadense grown in an open or in a dense stand.

PubMed

Watari, Ryoji; Nagashima, Hisae; Hirose, Tadaki

2014-07-01

Plants in open, uncrowded habitats typically have relatively short stems with many branches, whereas plants in crowded habitats grow taller and more slender at the expense of mechanical stability. There seems to be a trade-off between height growth and mechanical stability, and this study addresses how stand density influences stem extension and consequently plant safety margins against mechanical failure. Xanthium canadense plants were grown either solitarily (S-plants) or in a dense stand (D-plants) until flowering. Internode dimensions and mechanical properties were measured at the metamer level, and the critical buckling height beyond which the plant elastically buckles under its own weight and the maximum lateral wind force the plant can withstand were calculated. Internodes were longer in D- than S-plants, but basal diameter did not differ significantly. Relative growth rates of internode length and diameter were negatively correlated to the volumetric solid fraction of the internode. Internode dry mass density was higher in S- than D-plants. Young's modulus of elasticity and the breaking stress were higher in lower metamers, and in D- than in S-plants. Within a stand, however, both moduli were positively related to dry mass density. The buckling safety factor, a ratio of critical buckling height to actual height, was higher in S- than in D-plants. D-plants were found to be approaching the limiting value 1. Lateral wind force resistance was higher in S- than in D-plants, and increased with growth in S-plants. Critical buckling height increased with height growth due mainly to an increase in stem stiffness and diameter and a reduction in crown/stem mass ratio. Lateral wind force resistance was enhanced due to increased tissue strength and diameter. The increase in tissue stiffness and strength with height growth plays a crucial role in maintaining a safety margin against mechanical failure in herbaceous species that lack the capacity for secondary growth. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Experimental tests of the effect of rotor diameter ratio and blade number to the cross-flow wind turbine performance

NASA Astrophysics Data System (ADS)

Susanto, Sandi; Tjahjana, Dominicus Danardono Dwi Prija; Santoso, Budi

2018-02-01

Cross-flow wind turbine is one of the alternative energy harvester for low wind speeds area. Several factors that influence the power coefficient of cross-flow wind turbine are the diameter ratio of blades and the number of blades. The aim of this study is to find out the influence of the number of blades and the diameter ratio on the performance of cross-flow wind turbine and to find out the best configuration between number of blades and diameter ratio of the turbine. The experimental test were conducted under several variation including diameter ratio between outer and inner diameter of the turbine and number of blades. The variation of turbine diameter ratio between inner and outer diameter consisted of 0.58, 0.63, 0.68 and 0.73 while the variations of the number of blades used was 16, 20 and 24. The experimental test were conducted under certain wind speed which are 3m/s until 4 m/s. The result showed that the configurations between 0.68 diameter ratio and 20 blade numbers is the best configurations that has power coefficient of 0.049 and moment coefficient of 0.185.

[Ultrasound measurement of fetal posterior fossa at 11 to 13⁺⁶ gestational weeks for screening open spina bifida].

PubMed

Qin, Feng-Zhen; Li, Sheng-Li; Wen, Hua-Xuan; Ouyang, Yu-Rong; Zheng, Qiong; Bi, Jing-Ru

2014-06-01

To establish the normal reference ranges of transabdominal ultrasound measurements of the posterior fossa structure in fetuses at 11 to 13⁺⁶ gestational weeks and explore their clinical value in screening open spina bifida (OSB). Between January, 2013 and September, 541 randomly selected normal fetuses underwent nuchal translucency at the gestational age 11 to 13⁺⁶ weeks. The parameters of the posterior fossa were measured in mid-sagittal view of the fetal face and the axial view of the transverse cerebellum insonated through the anterior fontanel by transabdominal ultrasound to establish the normal reference ranges. The measurements were obtained from 3 fetuses with OSB for comparison with the reference ranges. In normal fetuses, the parameters of the posterior fossa measured in the two views showed no significant differences (P>0.05). Two high echogenic lines were observed in normal fetuses, as compared with one in fetuses with OSB representing the posterior border of the brain stem and the anterior border of the fourth ventricle. The line between the posterior border of the fourth ventricle and the anterior border of the cisterna magna was not displayed in fetuses with OSB. The anteroposterior diameters of the brain stem, the fourth ventricle, and cisterna magna all increased in positive correlation with the crown-lump length in normal fetuses. In the 3 OSB fetuses, the anteroposterior diameter of the brain stem exceeded the 95th percentile and the anteroposterior diameter of fourth ventrical-cisterner magena was below the 5th percentile of the reference range for CRL; the brain stem to fourth ventrical-cisterner magena anteroposterior diameter ratio was increased to above 1. The established normal reference ranges of the parameters of fetal posterior fossa may provide assistance in early OSB detection. The absence of the posterior border of the fourth ventricle and the anterior border of the cisterna magna and a brainstem to fourth ventrical-cisterner magena anteroposterior diameter ratio greater than 1 can be indicative of OSB at 11 to 13⁺⁶ gestational weeks.

First-trimester sonographic findings associated with a Dandy-Walker malformation and inferior vermian hypoplasia.

PubMed

Bornstein, Eran; Goncalves Rodríguez, José Luis; Álvarez Pavón, Erika Carolina; Quiroga, Héctor; Or, Drorit; Divon, Michael Y

2013-10-01

We report 2 cases in which first-trimester measurements of the intracranial translucency and the brain stem-to-occipital bone diameter were markedly enlarged. This finding was thought to represent an abnormal fourth ventricle-cisterna magna complex. Subsequently, the diagnoses of a Dandy-Walker malformation with partial vermian agenesis in 1 case and inferior vermian hypoplasia in the other were established and confirmed by either postmortem autopsy or postnatal magnetic resonance imaging. These cases suggest that evaluation of the fourth ventricle-cisterna magna complex, by measuring the intracranial translucency or brain stem-to-occipital bone diameter may identify some cases with structural malformations of the cerebellum as early as the first trimester.

Phase rainbow refractometry for accurate droplet variation characterization.

PubMed

Wu, Yingchun; Promvongsa, Jantarat; Saengkaew, Sawitree; Wu, Xuecheng; Chen, Jia; Gréhan, Gérard

2016-10-15

We developed a one-dimensional phase rainbow refractometer for the accurate trans-dimensional measurements of droplet size on the micrometer scale as well as the tiny droplet diameter variations at the nanoscale. The dependence of the phase shift of the rainbow ripple structures on the droplet variations is revealed. The phase-shifting rainbow image is recorded by a telecentric one-dimensional rainbow imaging system. Experiments on the evaporating monodispersed droplet stream show that the phase rainbow refractometer can measure the tiny droplet diameter changes down to tens of nanometers. This one-dimensional phase rainbow refractometer is capable of measuring the droplet refractive index and diameter, as well as variations.

Predicting diameters inside bark for 10 important hardwood species

Treesearch

Donald E. Hilt; Everette D. Rast; Herman J. Bailey

1983-01-01

General models for predicting DIB/DOB ratios up the stem, applicable over wide geographic areas, have been developed for 10 important hardwood species. Results indicate that the ratios either decrease or remain constant up the stem. Methods for adjusting the general models to local conditions are presented. The prediction models can be used in conjunction with optical...

Use of three-point taper systems in timber cruising

Treesearch

James W. Flewelling; Richard L. Ernst; Lawrence M. Raynes

2000-01-01

Tree volumes and profiles are often estimated as functions of total height and DBH. Alternative estimators include form-class methods, importance sampling, the centroid method, and multi-point profile (taper) estimation systems; all of these require some measurement or estimate of upper stem diameters. The multi-point profile system discussed here allows for upper stem...

Felling and skidding productivity and harvesting cost in southern pine forests

Treesearch

R.A. Kluender; B.J. Stokes

1996-01-01

Sixteen stands were harvested at various levels of basal area removed (intensity). Chainsaw felling productivity was more sensitive to stem diameter than harvest intensity. Skidding productivity was highest when removing large trees at high intensity. Harvesting cost was more sensitive to stem size than harvest intensity, although harvest intensity was a very important...

Field trial of a tree injector in a weeding in West Virginia

Treesearch

Carter B. Gibbs

1963-01-01

In June 1960 a 5-acre plot of mixed hardwoods under intensive selection management on the Fernow Experimental Forest in West Virginia was weeded to eliminate poor-quality stems that were competing directly with desirable regeneration. Treatment was confined to stems in the 1- to 5-inch diameter (at breast height) classes.

Flail-Delimbing of Loblolly Pine - A Case Study

Treesearch

Bryce J. Stokes

1985-01-01

Flail-delimbing was tested in small-diameter loblolly pine. Most of the limbs left on the stems were less than 6 inches long. Over 75 percent of the delimbed stems had three or fewer remaining limbs. The cost was determined by comparing skidding-flailing with skidding only. The cost difference was approximately $6.00 per unit.

Methane Flux of Amazonian Peatland Ecosystems: Large Ecosystem Fluxes with Substantial Contribution from Palm (maritia Flexuosa) STEM Emissions

NASA Astrophysics Data System (ADS)

Van Haren, J. L. M.; Cadillo-Quiroz, H.

2015-12-01

Methane (CH4) emissions through plants have long been known in wetlands. However, most measurements have focused on stem tops and leaves. Recently, measurements at the lower parts of stems have shown that stem emissions can exceed soil CH4 emissions in Asian peatlands (Pangala et al. 2013). The addition of stem fluxes to soil fluxes for total ecosystem fluxes has the potential to bridge the discrepancy between modeled to measured and bottom-up to top-down flux estimates. Our measurements in peatlands of Peru show that especially Mauritia flexuosa, a palm species, can emit very large quantities of CH4, although most trees emitted at least some CH4. We used flexible stem chambers to adapt to stems of any size above 5cm in diameter. The chambers were sampled in closed loop with a Gasmet DX4015 for flux measurements, which lasted ~5 minutes after flushing with ambient air. We found that M. flexuosa stem fluxes decrease with height along the stem and were positively correlated with soil fluxes. Most likely CH4 is transported up the stem with the xylem water. Measured M. flexuosa stem fluxes below 1.5m averaged 11.2±1.5 mg-C m-2 h-1 (±95% CI) with a maximum of 123±3.5 mg-C m-2 h-1 (±SE), whereas soil fluxes averaged 6.7±1.7 mg-C m-2 h-1 (±95% CI) with a maximum of 31.6±0.4 mg-C m-2 h-1 (±SE). Significant CH4 fluxes were measured up to 5 m height along the stems. Combined with the high density of ~150 M. flexuosa individuals per hectare in these peatlands and the consistent diameter of ~30cm, the high flux rates add ~20% to the soil flux. With anywhere between 1 and 5 billion M. flexuosa stems across Amazon basin wetlands, stem fluxes from this palm species could represent a major addition to the overall Amazon basin CH4 flux.

Optimization of electrospun TSF nanofiber alignment and diameter to promote growth and migration of mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Qu, Jing; Zhou, Dandan; Xu, Xiaojing; Zhang, Feng; He, Lihong; Ye, Rong; Zhu, Ziyu; Zuo, Baoqi; Zhang, Huanxiang

2012-11-01

Silk fibroin scaffolds are a naturally derived biocompatible matrix with the potential for reconstructive surgical applications. In this study, tussah silk fibroin (TSF) nanofiber with different diameters (400 nm, 800 nm and 1200 nm) and alignment (random and aligned) were prepared by electrospinning, then the growth and migration of mesenchymal stem cells (MSCs) on these materials were further evaluated. CD90 immunofluorescence staining showed that fiber alignment exhibited a strong influence on the morphology of MSCs, indicating that the alignment of the scaffolds could determine the distribution of cells. Moreover, smaller diameter and aligned TSF scaffolds are more favorable to the growth of MSCs as compared with 800 nm and 1200 nm random TSF scaffolds. In addition, the increased migration speed and efficiency of MSCs induced by three-D TSF were verified, highlighting the guiding roles of TSF to the migrated MSCs. More importantly, 400 nm aligned TSF scaffolds dramatically improved cell migratory speed and further induced the most efficient migration of MSCs as compared with larger diameter TSF scaffolds. In conclusion, the data demonstrate that smaller diameter and aligned electrospun TSF represent valuable scaffolds for supporting and promoting MSCs growth and migration, thus raising the possibility of manipulating TSF scaffolds to enhance homing and therapeutic potential of MSCs in cellular therapy.

Performance of stem flow gauges in greenhouse and desert environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levitt, D.G.; Simpson, J.R.; Tipton, J.L.

1995-06-01

This study was conducted to evaluate the accuracy and general performance of a heat balance method for estimating transpirational sap flow through plant stems on two tree species in greenhouse and field experiments in Tucson, Arizona. Sap flow through 20-mm diameter stems of oak (Quercus virginiana `Heritage`) and mesquite (Prosopis alba `Colorado`.) trees in containers was measured using stem flow gauges and a precision balance, from January to October, 1991. Overall gauge accuracy, and the effects of gauge location on the tree stem, gauge ventilation, gauge insulation, sheath conductance factor (Ksh) selection method, and increased numbers of vertical thermocouple pairsmore » on gauge performance were evaluated.« less

Small-diameter trees used for chemithermomechanical pulps.

Treesearch

Gary C. Myers; R. James Barbour; Said M. AbuBakr

2003-01-01

To restore and maintain forest ecosystem health and function in the western interior of the United States, many small-diameter stems need to be removed from densely stocked stands. In general, these materials are underutilized. Information on the properties of these resources is needed to help forest managers understand when timber sales are a viable option to...

Profile models for estimating log end diameters in the Rocky Mountain Region

Treesearch

Raymond L. Czaplewski; Amy S. Brown; Raymond C. Walker

1989-01-01

The segmented polynomial stem profile model of Max and Burkhart was applied to seven tree species in the Rocky Mountain Region of the Forest Service. Errors were reduced over the entire data set by use of second-stage models that adjust for transformation bias and explained weak patterns in the residual diameter predictions.

Spacing trials using the Nelder Wheel

Treesearch

Walter B. Mark

1983-01-01

The Nelder Wheel is a single tree systematic experimental design. Its major application is for plantation spacing experiments. The design allows for the testing of a number of spacings in a small area. Data obtained is useful in determining the response of stem diameter and crown diameter to spacing. Data is not compatible with data from conventional plots unless...

Bark Thickness of 17-Year-Old Loblolly Pine Planted at Different Spacings

Treesearch

Donald P. Feduccia; William F. Mann

1975-01-01

Diameter at breast height was the only variable affecting double bark thickness at d.b.h. and midpoint of the merchantable stem for young loblolly pine planted at five initial spacings on plots with site indices of 77 to 111 feet. Bark thickness at the 4-inch top was not correlated with breast-height diameter.

The feasibility of remotely sensed data to estimate urban tree dimensions and biomass

Treesearch

Jun-Hak Lee; Yekang Ko; E. Gregory McPherson

2016-01-01

Accurately measuring the biophysical dimensions of urban trees, such as crown diameter, stem diameter, height, and biomass, is essential for quantifying their collective benefits as an urban forest. However, the cost of directly measuring thousands or millions of individual trees through field surveys can be prohibitive. Supplementing field surveys with remotely sensed...

Height-diameter allometry of tropical forest trees

Treesearch

T.R. Feldpausch; L. Banin; O.L. Phillips; T.R. Baker; S.L. Lewis; C.A. Quesada; K. Affum-Baffoe; E.J.M.M. Arets; N.J. Berry; M. Bird; E.S. Brondizio; P de Camargo; J. Chave; G. Djagbletey; T.F. Domingues; M. Drescher; P.M. Fearnside; M.B. Franca; N.M. Fyllas; G. Lopez-Gonzalez; A. Hladik; N. Higuchi; M.O. Hunter; Y. Iida; K.A. Salim; A.R. Kassim; M. Keller; J. Kemp; D.A. King; J.C. Lovett; B.S. Marimon; B.H. Marimon-Junior; E. Lenza; A.R. Marshall; D.J. Metcalfe; E.T.A. Mitchard; E.F. Moran; B.W. Nelson; R. Nilus; E.M. Nogueira; M. Palace; S. Patiño; K.S.-H. Peh; M.T. Raventos; J.M. Reitsma; G. Saiz; F. Schrodt; B. Sonke; H.E. Taedoumg; S. Tan; L. White; H. Woll; J. Lloyd

2011-01-01

Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical...

Effects of prescribed burning on ecophysiological, anatomical and stem hydraulic properties in Pinus pinea L.

PubMed

Battipaglia, Giovanna; Savi, Tadeja; Ascoli, Davide; Castagneri, Daniele; Esposito, Assunta; Mayr, Stefan; Nardini, Andrea

2016-08-01

Prescribed burning (PB) is a widespread management technique for wildfire hazard abatement. Understanding PB effects on tree ecophysiology is key to defining burn prescriptions aimed at reducing fire hazard in Mediterranean pine plantations, such as Pinus pinea L. stands. We assessed physiological responses of adult P. pinea trees to PB using a combination of dendroecological, anatomical, hydraulic and isotopic analyses. Tree-ring widths, xylem cell wall thickness, lumen area, hydraulic diameter and tree-ring δ(13)C and δ(18)O were measured in trees on burned and control sites. Vulnerability curves were elaborated to assess tree hydraulic efficiency or safety. Despite the relatively intense thermal treatment (the residence time of temperatures above 50 °C at the stem surface ranged between 242 and 2239 s), burned trees did not suffer mechanical damage to stems, nor significant reduction in radial growth. Moreover, the PB did not affect xylem structure and tree hydraulics. No variations in (13)C-derived water use efficiency were recorded. This confirmed the high resistance of P. pinea to surface fire at the stem base. However, burned trees showed consistently lower δ(18)O values in the PB year, as a likely consequence of reduced competition for water and nutrients due to the understory burning, which increased both photosynthetic activity and stomatal conductance. Our multi-approach analysis offers new perspectives on post-fire survival strategies of P. pinea in an environment where fires are predicted to increase in frequency and severity during the 21st century. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Surface topography during neural stem cell differentiation regulates cell migration and cell morphology.

PubMed

Czeisler, Catherine; Short, Aaron; Nelson, Tyler; Gygli, Patrick; Ortiz, Cristina; Catacutan, Fay Patsy; Stocker, Ben; Cronin, James; Lannutti, John; Winter, Jessica; Otero, José Javier

2016-12-01

We sought to determine the contribution of scaffold topography to the migration and morphology of neural stem cells by mimicking anatomical features of scaffolds found in vivo. We mimicked two types of central nervous system scaffolds encountered by neural stem cells during development in vitro by constructing different diameter electrospun polycaprolactone (PCL) fiber mats, a substrate that we have shown to be topographically similar to brain scaffolds. We compared the effects of large fibers (made to mimic blood vessel topography) with those of small-diameter fibers (made to mimic radial glial process topography) on the migration and differentiation of neural stem cells. Neural stem cells showed differential migratory and morphological reactions with laminin in different topographical contexts. We demonstrate, for the first time, that neural stem cell biological responses to laminin are dependent on topographical context. Large-fiber topography without laminin prevented cell migration, which was partially reversed by treatment with rock inhibitor. Cell morphology complexity assayed by fractal dimension was inhibited in nocodazole- and cytochalasin-D-treated neural precursor cells in large-fiber topography, but was not changed in small-fiber topography with these inhibitors. These data indicate that cell morphology has different requirements on cytoskeletal proteins dependent on the topographical environment encountered by the cell. We propose that the physical structure of distinct scaffolds induces unique signaling cascades that regulate migration and morphology in embryonic neural precursor cells. J. Comp. Neurol. 524:3485-3502, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Profitability of precommercially thinning oak stump sprouts

Treesearch

John P. Dwyer; Daniel C. Dey; William B. Kurtz

1993-01-01

Thinning oak stump sprouts to a single stem at an early age will increase diameter growth of the released stem. However, precommercial thinning represents a substantial investment which must be carried for many years before any returns are realized. We estimated the incremental gains in yield and the present net worth for five crop-tree release treatments of 5-year-old...

Growth Reponse of Loblolly Pine to Intermediate Treatment of Fire, Herbicide, and Fertilizer: Preliminary Results

Treesearch

L.M. Marino; B.P. Oswald; K.W. Farrish; H.M. Williams; Daniel R. Unger

2002-01-01

Crown area is an important factor in determining stem development. This study examined the changes in stem diameter per unit area of crown due to treatment with fire, herbicide, fertilizer, and tree-thinning practice. The experimental sites were mid-rotation loblolly pine (Pinus taeda) plantations that were thinned one year before treatment. Site 1...

Effect of simulated insect damage on growth and survival of northern red oak (Quercus rubra L.) seedlings

Treesearch

Susan L. Wright; Richard W. Hall; John W. Peacock

1989-01-01

Effects of simulated insect damage—artificial defoliation and root damage in combination with two levels of watering—were studied to determine the potential effect on northern red oak seedlings (Quercus rubra L.). Treatments and treatment combinations caused significant differences in stem diameter, percentage of stem dieback, and mortality....

Profitability of Precommericially Thinning Oak Stump Sprouts

Treesearch

John P. Dwyer; Daniel C. Dey; William B. Kurtz

1993-01-01

Thinning oak stump sprouts to a single stem at an early age will increase diameter growth of the released stem. However, percommercial thinning represents a substantial investment which must be carried for many years before any returns are realized. We estimated the incremental gains in yield and the present net worth for five crop-tree release treatments of 5-yr-old...

Modeling the effect of competition on tree diameter growth as applied in STEMS.

Treesearch

Margaret R. Holdaway

1984-01-01

The modifier function used in STEMS (Stand and Tree Evaluation and Modeling System) mathematically represents the effect that the surrounding forest community has on the growth of an individual tree. This paper 1) develops the most recent modifier function, 2) discusses its form, 3) reports the results of the analysis with biological considerations and 4) evaluates the...

A predictive nondestructive model for the covariation of tree height, diameter, and stem volume scaling relationships.

PubMed

Zhang, Zhongrui; Zhong, Quanlin; Niklas, Karl J; Cai, Liang; Yang, Yusheng; Cheng, Dongliang

2016-08-24

Metabolic scaling theory (MST) posits that the scaling exponents among plant height H, diameter D, and biomass M will covary across phyletically diverse species. However, the relationships between scaling exponents and normalization constants remain unclear. Therefore, we developed a predictive model for the covariation of H, D, and stem volume V scaling relationships and used data from Chinese fir (Cunninghamia lanceolata) in Jiangxi province, China to test it. As predicted by the model and supported by the data, normalization constants are positively correlated with their associated scaling exponents for D vs. V and H vs. V, whereas normalization constants are negatively correlated with the scaling exponents of H vs. D. The prediction model also yielded reliable estimations of V (mean absolute percentage error = 10.5 ± 0.32 SE across 12 model calibrated sites). These results (1) support a totally new covariation scaling model, (2) indicate that differences in stem volume scaling relationships at the intra-specific level are driven by anatomical or ecophysiological responses to site quality and/or management practices, and (3) provide an accurate non-destructive method for predicting Chinese fir stem volume.

Large Diameter Femoral Heads Impose Significant Alterations on the Strains Developed on Femoral Component and Bone: A Finite Element Analysis

PubMed Central

Theodorou, E.G; Provatidis, C.G; Babis, G.C; Georgiou, C.S; Megas, P.D

2011-01-01

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost’s law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used. PMID:21792381

Large diameter femoral heads impose significant alterations on the strains developed on femoral component and bone: a finite element analysis.

PubMed

Theodorou, E G; Provatidis, C G; Babis, G C; Georgiou, C S; Megas, P D

2011-01-01

Total Hip Arthroplasty aims at fully recreating a functional hip joint. Over the past years modular implant systems have become common practice and are widely used, due to the surgical options they provide. In addition Big Femoral Heads have also been implemented in the process, providing more flexibility for the surgeon. The current study aims at investigating the effects that femoral heads of bigger diameter may impose on the mechanical behavior of the bone-implant assembly. Using data acquired by Computed Tomographies and a Coordinate Measurement Machine, a cadaveric femur and a Profemur-E modular stem were fully digitized, leading to a three dimensional finite element model in ANSYS Workbench. Strains and stresses were then calculated, focusing on areas of clinical interest, based on Gruen zones: the calcar and the corresponding below the greater trochanter area in the proximal femur, the stem tip region and a profile line along linea aspera. The performed finite elements analysis revealed that the use of large diameter heads produces significant changes in strain development within the bone volume, especially in the lateral side. The application of Frost's law in bone remodeling, validated the hypothesis that for all diameters normal bone growth occurs. However, in the calcar area lower strain values were recorded, when comparing with the reference model featuring a 28mm femoral head. Along line aspera and for the stem tip area, higher values were recorded. Finally, stresses calculated on the modular neck revealed increased values, but without reaching the yield strength of the titanium alloy used.

Establishment and characterization of a unique 1 microm diameter liver-derived progenitor cell line.

PubMed

Aravalli, Rajagopal N; Behnan Sahin, M; Cressman, Erik N K; Steer, Clifford J

2010-01-01

Liver-derived progenitor cells (LDPCs) are recently identified novel stem/progenitor cells from healthy, unmanipulated adult rat livers. They are distinct from other known liver stem/progenitor cells such as the oval cells. In this study, we have generated a LDPC cell line RA1 by overexpressing the simian virus 40 (SV40) large T antigen (TAg) in primary LDPCs. This cell line was propagated continuously for 55 passages in culture, after which it became senescent. Interestingly, following transformation with SV40 TAg, LDPCs decreased in size significantly and the propagating cells measured 1 microm in diameter. RA1 cells proliferated in vitro with a doubling time of 5-7 days, and expressed cell surface markers of LDPCs. In this report, we describe the characterization of this novel progenitor cell line that might serve as a valuable model to study liver cell functions and stem cell origin of liver cancers. Copyright 2009 Elsevier Inc. All rights reserved.

The Importance of Large-Diameter Trees to Forest Structural Heterogeneity

PubMed Central

Lutz, James A.; Larson, Andrew J.; Freund, James A.; Swanson, Mark E.; Bible, Kenneth J.

2013-01-01

Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥1 cm dbh, all 1,966 snags ≥10 cm dbh, and all shrub patches ≥2 m2. Basal area of the 26 woody species was 62.18 m2/ha, of which 61.60 m2/ha was trees and 0.58 m2/ha was tall shrubs. Large-diameter trees (≥100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P≤0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses. PMID:24376579

The importance of large-diameter trees to forest structural heterogeneity.

PubMed

Lutz, James A; Larson, Andrew J; Freund, James A; Swanson, Mark E; Bible, Kenneth J

2013-01-01

Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥ 1 cm dbh, all 1,966 snags ≥ 10 cm dbh, and all shrub patches ≥ 2 m(2). Basal area of the 26 woody species was 62.18 m(2)/ha, of which 61.60 m(2)/ha was trees and 0.58 m(2)/ha was tall shrubs. Large-diameter trees (≥ 100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P ≤ 0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses.

Changes in wood density, wood anatomy and hydraulic properties of the xylem along the root-to-shoot flow path in tropical rainforest trees.

PubMed

Schuldt, Bernhard; Leuschner, Christoph; Brock, Nicolai; Horna, Viviana

2013-02-01

It is generally assumed that the largest vessels are occurring in the roots and that vessel diameters and the related hydraulic conductance in the xylem are decreasing acropetally from roots to leaves. With this study in five tree species of a perhumid tropical rainforest in Sulawesi (Indonesia), we searched for patterns in hydraulic architecture and axial conductivity along the flow path from small-diameter roots through strong roots and the trunk to distal sun-canopy twigs. Wood density differed by not more than 10% across the different flow path positions in a species, and branch and stem wood density were closely related in three of the five species. Other than wood density, the wood anatomical and xylem hydraulic traits varied in dependence on the position along the flow path, but were unrelated to wood density within a tree. In contrast to reports from conifers and certain dicotyledonous species, we found a hump-shaped variation in vessel diameter and sapwood area--specific conductivity along the flow path in all five species with a maximum in the trunk and strong roots and minima in both small roots and twigs; the vessel size depended on the diameter of the organ. This pattern might be an adaptation to the perhumid climate with a low risk of hydraulic failure. Despite a similar mean vessel diameter in small roots and twigs, the two distal organs, hydraulically weighted mean vessel diameters were on average 30% larger in small roots, resulting in ∼ 85% higher empirical and theoretical specific conductivities. Relative vessel lumen area in percent of sapwood area decreased linearly by 70% from roots to twigs, reflecting the increase in sclerenchymatic tissue and tracheids in acropetal direction in the xylem. Vessel size was more closely related to the organ diameter than to the distance along the root-to-shoot flow path. We conclude that (i) the five co-occurring tree species show convergent patterns in their hydraulic architecture despite different growth strategies, and (ii) the paradigm assuming continuous acropetal vessel tapering and decrease in specific conductance from fine roots towards distal twigs needs reconsideration.

Compatible taper equation for loblolly pine

Treesearch

J. P. McClure; R. L. Czaplewski

1986-01-01

Cao's compatible, segmented polynomial taper equation (Q. V. Cao, H. E. Burkhart, and T. A. Max. For. Sci. 26: 71-80. 1980) is fitted to a large loblolly pine data set from the southeastern United States. Equations are presented that predict diameter at a given height, height to a given top diameter, and volume below a given position on the main stem. All...

Effects of uneven-aged and diameter-limit management on West Virginia tree and wood quality

Treesearch

Michael C. Wiemann; Thomas M. Schuler; John E. Baumgras

2004-01-01

Uneven-aged and diameter-limit management were compared with an unmanaged control on the Fernow Experimental Forest near Parsons, West Virginia, to determine how treatment affects the quality of red oak (Quercus rubra L.), sugar maple (Acer saccharum Marsh.), and yellow-poplar (Liriodendron tulipifera L.). Periodic harvests slightly increased stem lean, which often...

Stem Profile for Southern Equations for Southern Tree Species

Treesearch

Alexander Clark; Ray A. Souter; Bryce E. Schlaegel

1991-01-01

Form-class segmented-profile equations for 58 southern tree species and species groups are presented.The profile equations are based on taper data for 13,469 trees sampled in natural stands in many locations across the South.The profile equations predict diameter at any given height, height to give diameter, and volume between two heights.Equation coefficients for use...

Seasonal and diel variation in xylem CO2 concentration and sap pH in sub-Mediterranean oak stems.

PubMed

Salomón, Roberto; Valbuena-Carabaña, María; Teskey, Robert; McGuire, Mary Anne; Aubrey, Doug; González-Doncel, Inés; Gil, Luis; Rodríguez-Calcerrada, Jesús

2016-04-01

Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*]. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Diel growth dynamics in tree stems: linking anatomy and ecophysiology.

PubMed

Steppe, Kathy; Sterck, Frank; Deslauriers, Annie

2015-06-01

Impacts of climate on stem growth in trees are studied in anatomical, ecophysiological, and ecological disciplines, but an integrative framework to assess those impacts remains lacking. In this opinion article, we argue that three research efforts are required to provide that integration. First, we need to identify the missing links in diel patterns in stem diameter and stem growth and relate those patterns to the underlying mechanisms that control water and carbon balance. Second, we should focus on the understudied mechanisms responsible for seasonal impacts on such diel patterns. Third, information on stem anatomy and ecophysiology should be integrated in the same experiments and mechanistic plant growth models to capture both diel and seasonal scales. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimizing Mechanical Alignment With Modular Stems in Revision TKA.

PubMed

Fleischman, Andrew N; Azboy, Ibrahim; Restrepo, Camilo; Maltenfort, Mitchell G; Parvizi, Javad

2017-09-01

Although mechanical alignment is critical for optimal function and long-term implant durability, the role of modular stems in achieving ideal alignment is unclear. We identified 319 revision total knee arthroplasty from 2003-2013, for which stem length, stem diameter, and stem fixation method were recorded prospectively. Three-dimensional canal-filling ratio, the product of canal-filling ratio at the stem tip in both the anteroposterior and lateral planes, and alignment were measured radiographically. Ideal alignment of the femur was considered to be 95° in the anteroposterior (AP) plane and from 1° of extension to 4° of flexion in the lateral plane, and ideal tibial alignment was considered to be 90° in the AP plane. Even after accounting for difference in stem size and canal-fill, ideal AP alignment was more reliably achieved with press-fit stems. Furthermore, increased engagement of the diaphysis and its anatomical axis with canal-filling stems facilitates accurate alignment. Copyright © 2017 Elsevier Inc. All rights reserved.

Trampling, defoliation and physiological integration affect growth, morphological and mechanical properties of a root-suckering clonal tree.

PubMed

Xu, Liang; Yu, Fei-Hai; van Drunen, Elles; Schieving, Feike; Dong, Ming; Anten, Niels P R

2012-04-01

Grazing is a complex process involving the simultaneous occurrence of both trampling and defoliation. Clonal plants are a common feature of heavily grazed ecosystems where large herbivores inflict the simultaneous pressures of trampling and defoliation on the vegetation. We test the hypothesis that physiological integration (resource sharing between interconnected ramets) may help plants to deal with the interactive effects of trampling and defoliation. In a field study, small and large ramets of the root-suckering clonal tree Populus simonii were subjected to two levels of trampling and defoliation, while connected or disconnected to other ramets. Plant responses were quantified via survival, growth, morphological and stem mechanical traits. Disconnection and trampling increased mortality, especially in small ramets. Trampling increased stem length, basal diameter, fibrous root mass, stem stiffness and resistance to deflection in connected ramets, but decreased them in disconnected ones. Trampling decreased vertical height more in disconnected than in connected ramets, and reduced stem mass in disconnected ramets but not in connected ramets. Defoliation reduced basal diameter, leaf mass, stem mass and leaf area ratio, but did not interact with trampling or disconnection. Although clonal integration did not influence defoliation response, it did alleviate the effects of trampling. We suggest that by facilitating resource transport between ramets, clonal integration compensates for trampling-induced damage to fine roots.

Origins and implications of pluripotent stem cell variability and heterogeneity

PubMed Central

Cahan, Patrick; Daley, George Q.

2014-01-01

Pluripotent stem cells constitute a platform to model disease and developmental processes and can potentially be used in regenerative medicine. However, not all pluripotent cell lines are equal in their capacity to differentiate into desired cell types in vitro. Genetic and epigenetic variations contribute to functional variability between cell lines and heterogeneity within clones. These genetic and epigenetic variations could ‘lock’ the pluripotency network resulting in residual pluripotent cells or alter the signalling response of developmental pathways leading to lineage bias. The molecular contributors to functional variability and heterogeneity in both embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are only beginning to emerge, yet they are crucial to the future of the stem cell field. PMID:23673969

Forced convection and flow boiling with and without enhancement devices for top-side-heated horizontal channels

NASA Technical Reports Server (NTRS)

Boyd, Ronald D., Sr.; Turknett, Jerry C.

1989-01-01

The effect of enhancement devices on flow boiling heat transfer in coolant channels, which are heated either from the top side or uniformly was studied. Studies are completed of the variations in the local (axial and circumferential) and mean heat transfer coefficients in horizontal, top-heated coolant channels with smooth walls and internal heat transfer enhancement devices. The working fluid is freon-11. The objectives are to: (1) examine the variations in both the mean and local (axial and circumferential) heat transfer coefficients for a circular coolant channel with either smooth walls or with both a twisted tape and spiral finned walls; (2) examine the effect of channel diameter (and the length-to-diameter aspect ratio) variations for the smooth wall channel; and (3) develop and improved data reduction analysis. The case of the top-heated, horizontal flow channel with smooth wall (1.37 cm inside diameter, and 122 cm heated length) was completed. The data were reduced using a preliminary analysis based on the heated hydraulic diameter. Preliminary examination of the local heat transfer coefficient variations indicated that there are significant axial and circumferential variations. However, it appears that the circumferential variation is more significant than the axial ones. In some cases, the circumferential variations were as much as a factor of ten. The axial variations rarely exceeded a factor of three.

Ethanol synthesis and aerobic respiration in the laboratory by leader segments of Douglas-fir seedlings from winter and spring.

PubMed

Joseph, Gladwin; Kelsey, Rick G

2004-05-01

Stem segments from terminal leaders of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, seedlings were sampled in mid-December when cambial cells were dormant. The residual, debudded leaders were resampled again in early May when the cambium was metabolically active. May stems had higher constitutive ethanol concentrations than December stems. This was not the result of cambial hypoxia generated by rapid spring respiration rates, because when aerobic respiration was stimulated by incubating the stems in air at 30 degrees C ethanol production was induced in December, but not in May. Rapid respiration rates at 30 degrees C may have depleted O(2) supplies and induced ethanol production in December stems because dormant, thick-walled cambial cells may be less permeable to CO(2) and O(2), compared with metabolically active, thin-walled cambial cells in May. December stem segments incubated in a N(2) atmosphere at 30 degrees C synthesized 1.8 times more ethanol than segments from May, most likely because spring growth had reduced the soluble sugars available for fermentation. CO(2) efflux from May stems (after 5.5 h of incubation at 30 degrees C) was equal to December stems per unit volume, but greater than December stems per unit surface area. N(2)-induced ethanol concentrations were positively related with CO(2) efflux per unit volume, indicating that rapidly respiring leaders can maintain rapid fermentation rates, provided soluble sugars are readily available. N(2)-induced ethanol and CO(2) efflux per unit volume declined with increasing leader diameter in both seasons, whereas there were no relationships between CO(2) efflux per unit surface area and diameter. Cambium physiology and phenology influence the induction of fermentation and concentrations of ethanol produced in terminal leaders of Douglas-fir, and probably other conifers as well. This needs to be considered when comparing fermentation among species, or comparing individuals from different seasons, or disparate ages within a species.

Simulating the effects of climatic variation on stem carbon accumulation of a ponderosa pine stand: comparison with annual growth increment data.

PubMed

Hunt, E R; Martin, F C; Running, S W

1991-01-01

Simulation models of ecosystem processes may be necessary to separate the long-term effects of climate change on forest productivity from the effects of year-to-year variations in climate. The objective of this study was to compare simulated annual stem growth with measured annual stem growth from 1930 to 1982 for a uniform stand of ponderosa pine (Pinus ponderosa Dougl.) in Montana, USA. The model, FOREST-BGC, was used to simulate growth assuming leaf area index (LAI) was either constant or increasing. The measured stem annual growth increased exponentially over time; the differences between the simulated and measured stem carbon accumulations were not large. Growth trends were removed from both the measured and simulated annual increments of stem carbon to enhance the year-to-year variations in growth resulting from climate. The detrended increments from the increasing LAI simulation fit the detrended increments of the stand data over time with an R(2) of 0.47; the R(2) increased to 0.65 when the previous year's simulated detrended increment was included with the current year's simulated increment to account for autocorrelation. Stepwise multiple linear regression of the detrended increments of the stand data versus monthly meteorological variables had an R(2) of 0.37, and the R(2) increased to 0.47 when the previous year's meteorological data were included to account for autocorrelation. Thus, FOREST-BGC was more sensitive to the effects of year-to-year climate variation on annual stem growth than were multiple linear regression models.

Response to crop-tree release by 7-year-old stems of yellow-poplar and black cherry

Treesearch

G.R. Jr. Trimble; G.R. Jr. Trimble

1973-01-01

Five years after crop-tree release of yellow-poplar and black cherry sterns in a 7-year-old stand of Appalachian hardwoods, measurements indicated that released trees were but slightly superior to control trees in height, diameter, and crown position. Sprout regrowth of cut tree stems and grapevines had largely nullified the effects of release. Indications are that for...

Mechanical site preparation and oust XP effects on stem biomass in three-year-old nuttall oak seedlings planted on a former agricultural field

Treesearch

Andrew B. Self; Andrew W. Ezell; Dennis Rowe; Emily B. Schultz; John D. Hodges

2015-01-01

Mechanical site preparation is frequently proposed to alleviate problematic soil conditions when afforesting retired agricultural fields. Without management of soil problems, any seedlings planted in these areas may exhibit poor growth and survival. Seeding height and groundline diameter are often used to evaluate effects of site preparation methods, but stem biomass...

Growth and Development of Thinned Versus Unthinned Yellow-Poplar Sprout Clumps

Treesearch

Donald E. Beck

1977-01-01

Yellow-poplar stump sprouts are capable of very rapid growth and often dominate stands on good sites following harvest cutting. Thinning to one stem per stump at 6 years of age did not affect either height or diameter growth over the succeeding 18 years. The untreated clumps thinned themselves to an average of two stems per clump during the same time period. Thinning...

Effects of Measurement Errors on Individual Tree Stem Volume Estimates for the Austrian National Forest Inventory

Treesearch

Ambros Berger; Thomas Gschwantner; Ronald E. McRoberts; Klemens Schadauer

2014-01-01

National forest inventories typically estimate individual tree volumes using models that rely on measurements of predictor variables such as tree height and diameter, both of which are subject to measurement error. The aim of this study was to quantify the impacts of these measurement errors on the uncertainty of the model-based tree stem volume estimates. The impacts...

Fiber lengths in stems and branches of small hardwoods on southern pine sites

Treesearch

F. G. Manwiller

1974-01-01

The 22 species selected for analysis comprise over 95 percent of the hardwood volume occurring on pine sites. Ten trees 6 inch. in diameter at breast height (DBH) of each species were taken from throughout that portion of the species' range occurring in the South. Pie-shaped wedges, removed at 48-inch intervals along the stem and each branch, were combined within...

Fiber lengths in stems and brances of small hardwoods on southern pine sites

Treesearch

Floyd G. Manwiller

1974-01-01

The 22 species selected for analysis comprise over 95 percent of the hardwood volume occurring on pine sites. Ten trees 6 inches in diameter at breast height (DBH) of each species were taken from throughout that portion of the spcies' range occurring in the South. Pie-shaped wedges, removed at 48-inch intervals along the stem and each branch, were combined within...

Relative maxima of diameter and basal area

Treesearch

Thomas B. Lynch; Difei Zhang

2012-01-01

It has often been observed that maximum dbh growth occurs at an earlier age than maximum individual tree basal area growth. This can be deduced from the geometry of the tree stem, by observing that a dbh increment at a given radius will be associated with a larger basal area increment than an equal dbh increment occurring at a shorter radius from the stem center. Thus...

Efficacy of generic allometric equations for estimating biomass: a test in Japanese natural forests.

PubMed

Ishihara, Masae I; Utsugi, Hajime; Tanouchi, Hiroyuki; Aiba, Masahiro; Kurokawa, Hiroko; Onoda, Yusuke; Nagano, Masahiro; Umehara, Toru; Ando, Makoto; Miyata, Rie; Hiura, Tsutom

2015-07-01

Accurate estimation of tree and forest biomass is key to evaluating forest ecosystem functions and the global carbon cycle. Allometric equations that estimate tree biomass from a set of predictors, such as stem diameter and tree height, are commonly used. Most allometric equations are site specific, usually developed from a small number of trees harvested in a small area, and are either species specific or ignore interspecific differences in allometry. Due to lack of site-specific allometries, local equations are often applied to sites for which they were not originally developed (foreign sites), sometimes leading to large errors in biomass estimates. In this study, we developed generic allometric equations for aboveground biomass and component (stem, branch, leaf, and root) biomass using large, compiled data sets of 1203 harvested trees belonging to 102 species (60 deciduous angiosperm, 32 evergreen angiosperm, and 10 evergreen gymnosperm species) from 70 boreal, temperate, and subtropical natural forests in Japan. The best generic equations provided better biomass estimates than did local equations that were applied to foreign sites. The best generic equations included explanatory variables that represent interspecific differences in allometry in addition to stem diameter, reducing error by 4-12% compared to the generic equations that did not include the interspecific difference. Different explanatory variables were selected for different components. For aboveground and stem biomass, the best generic equations had species-specific wood specific gravity as an explanatory variable. For branch, leaf, and root biomass, the best equations had functional types (deciduous angiosperm, evergreen angiosperm, and evergreen gymnosperm) instead of functional traits (wood specific gravity or leaf mass per area), suggesting importance of other traits in addition to these traits, such as canopy and root architecture. Inclusion of tree height in addition to stem diameter improved the performance of the generic equation only for stem biomass and had no apparent effect on aboveground, branch, leaf, and root biomass at the site level. The development of a generic allometric equation taking account of interspecific differences is an effective approach for accurately estimating aboveground and component biomass in boreal, temperate, and subtropical natural forests.

Comparative characterization of stromal vascular cells derived from three types of vascular wall and adipose tissue.

PubMed

Yang, Santsun; Eto, Hitomi; Kato, Harunosuke; Doi, Kentaro; Kuno, Shinichiro; Kinoshita, Kahori; Ma, Hsu; Tsai, Chi-Han; Chou, Wan-Ting; Yoshimura, Kotaro

2013-12-01

Multipotent stem/progenitor cells localize perivascularly in many organs and vessel walls. These tissue-resident stem/progenitor cells differentiate into vascular endothelial cells, pericytes, and other mesenchymal lineages, and participate in physiological maintenance and repair of vasculatures. In this study, we characterized stromal vascular cells obtained through the explant culture method from three different vessel walls in humans: arterial wall (ART; >500 μm in diameter), venous wall (VN; >500 μm in diameter), and small vessels in adipose tissue (SV; arterioles and venules, <100 μm in diameter). These were examined for functionality and compared with adipose-derived stem/stromal cells (ASCs). All stromal vascular cells of different origins presented fibroblast-like morphology and we could not visually discriminate one population from another. Flow cytometry showed that the cultured population heterogeneously expressed a variety of surface antigens associated with stem/progenitor cells, but CD105 was expressed by most cells in all groups, suggesting that the cells generally shared the characteristics of mesenchymal stem cells. Our histological and flow cytometric data suggested that the main population of vessel wall-derived stromal vascular cells were CD34(+)/CD31(-) and came from the tunica adventitia and areola tissue surrounding the adventitia. CD271 (p75NTR) was expressed by the vasa vasorum in the VN adventitia and by a limited population in the adventitia of SV. All three populations differentiated into multiple lineages as did ASCs. ART cells induced the largest quantity of calcium formation in the osteogenic medium, whereas ASCs showed the greatest adipogenic differentiation. SV and VN stromal cells had greater potency for network formation than did ART stromal cells. In conclusion, the three stromal vascular populations exhibited differential functional properties. Our results have clinical implications for vascular diseases such as arterial wall calcification and possible applications to regenerative therapies involving each vessel wall-resident stromal population.

Oriental bittersweet (Celastrus orbiculatus): Spreading by fire

USGS Publications Warehouse

Pavlovic, Noel B.; Leicht-Young, Stacey A.; Grundel, Ralph

2016-01-01

In many forest ecosystems, fire is critical in maintaining indigenous plant communities, but can either promote or arrest the spread of invasive species depending on their regeneration niche and resprouting ability. We examined the effects of cutting and burning treatments on the vegetative response (cover, stem density) and root resources of Oriental bittersweet (Celastrus orbiculatus), a liana invasive to North America that was introduced from East Asia. Treatments were control, spring cut, spring burn, spring cut & burn, summer cut, fall cut, fall burn, fall cut & burn, and fall herbicide. Cover was reduced the greatest by herbicide and summer cutting treatments, but increased more in the second year on moraine soils than on sandy soils. Burning and cutting & burning combined resulted in a resprout density four times greater than stem density prior to treatment for stems <2.5 mm diameter than cutting alone. For stems, across all diameter classes, there was a more than 100% increase in stem density with burning and almost a 300% increase in stem density with cutting & burning in the spring. Density of resprouts and root-suckers, and survival increased with increasing stem size. While cutting of C. orbiculatus during the growing season (summer) reduced total nonstructural carbohydrates by 50% below early growing season levels and 75% below dormant season levels, burning did not significantly reduce total nonstructural carbohydrates. Thus, Oriental bittersweet is quite responsive to burning as a disturbance and resprouting and root-suckering creates additional opportunities for growth and attainment of the forest canopy. The positive response of Oriental bittersweet to burning has important implications for management of invasive lianas in fire-dependent forest landscapes.

Experimental and Analytical Determination of the Motion of Hydraulically Operated Valve Stems in Oil Engine Injection Systems

NASA Technical Reports Server (NTRS)

Gelalles, A G; Rothrock, A M

1930-01-01

This research on the pressure variations in the injection system of the N.A.C.A. Spray Photography Equipment and on the effects of these variations on the motion of the timing valve stem was undertaken in connection with the study of fuel injection systems for high-speed oil engines. The methods of analysis of the pressure variations and the general equation for the motion of the spring-loaded stem for the timing valve are applicable to a spring-loaded automatic injection valve, and in general to all hydraulically operated valves. A sample calculation for a spring-loaded automatic injection valve is included.

Testicular germ line cell identification, isolation, and transplantation in two North American catfish species.

PubMed

Shang, Mei; Su, Baofeng; Perera, Dayan A; Alsaqufi, Ahmed; Lipke, Elizabeth A; Cek, Sehriban; Dunn, David A; Qin, Zhenkui; Peatman, Eric; Dunham, Rex A

2018-04-01

Our aim was to transplant blue catfish germ line stem cells into blastulae of triploid channel catfish embryos to produce interspecific xenogenic catfish. The morphological structure of the gonads of blue catfish (Ictalurus furcatus) in ~ 90- to 100-day-old juveniles, two-year-old juveniles, and mature adults was studied histologically. Both oogonia (12-15 μm, diameter with distinct nucleus 7-8 μm diameter) and spermatogonia (12-15 μm, with distinct nucleus 6-7.5 μm diameter) were found in all ages of fish. The percentage of germ line stem cells was higher in younger blue catfish of both sexes. After the testicular tissue was trypsinized, a discontinuous density gradient centrifugation was performed using 70, 45, and 35% Percoll to enrich the percentage of spermatogonial stem cells (SSCs). Four distinct cell bands were generated after the centrifugation. It was estimated that 50% of the total cells in the top band were type A spermatogonia (diameter 12-15 μm) and type B spermatogonia (diameter 10-11 μm). Germ cells were confirmed with expression of vasa. Blastula-stage embryos of channel catfish (I. punctatus) were injected with freshly dissociated blue catfish testicular germ cells as donor cells for transplantation. Seventeen days after the transplantation, 33.3% of the triploid channel catfish fry were determined to be xenogenic catfish. This transplantation technique was efficient, and these xenogenic channel catfish need to be grown to maturity to verify their reproductive capacity and to verify that for the first time SSCs injected into blastulae were able to migrate to the genital ridge and colonize. These results open the possibility of artificially producing xenogenic channel catfish males that can produce blue catfish sperm and mate with normal channel catfish females naturally. The progeny would be all C × B hybrid catfish, and the efficiency of hybrid catfish production could be improved tremendously in the catfish industry.

Development of top heights and corresponding diameters in high-elevation noble fir plantations

Treesearch

Robert O. Curtis

2015-01-01

Height and diameter growth of noble fir (Abies procera Rehd.) trees included in the largest 40 stems per acre were compared in a study that included five precommercial thinning spacings plus no thinning, in each of eight replications, at elevations from 2,200 to 4,100 feet in the western Cascade Mountains of Washington and Oregon. Height growth rates were not affected...

Ground-layer plant community responses to even-age and uneven-age silvicultural treatments in Wisconsin northern hardwood forests

Treesearch

Cristel C. Kern; Brian J. Palik; Terry F. Strong

2006-01-01

We evaluated ground-layer plant diversity and community composition in northern hardwood forests among uncut controls and stands managed with even-age or uneven-age silvicultural systems. Even-age treatments included diameter-limit cuttings (20-cm diameter at 30-cm stem height) in 1952 and shelterwood removals in 1964. Uneven-age treatments included three intensities...

The redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae) uses stem silhouette diameter as a visual host-finding cue

Treesearch

Albert (Bud) Mayfield; Cavell Brownie

2013-01-01

The redbay ambrosia beetle (Syleborus glabratus Eichhoff) is an invasive pest and vector of the pathogen that causes laurel wilt disease in Lauraceous tree species in the eastern United States. This insect uses olfactory cues during host finding, but use of visual cues by X. Glabratus has not been previously investigated and may help explain diameter...

Modeling Caribbean tree stem diameters from tree height and crown width measurements

Treesearch

Thomas Brandeis; KaDonna Randolph; Mike Strub

2009-01-01

Regression models to predict diameter at breast height (DBH) as a function of tree height and maximum crown radius were developed for Caribbean forests based on data collected by the U.S. Forest Service in the Commonwealth of Puerto Rico and Territory of the U.S. Virgin Islands. The model predicting DBH from tree height fit reasonably well (R2 = 0.7110), with...

Diameter-limit harvesting: effects of residual trees on regeneration dynamics in Appalachian hardwoods

Treesearch

Travis DeLuca; Mary Ann Fajvan; Gary Miller

2009-01-01

Ten-years after diameter-limit harvesting in an Appalachian hardwood stand, the height, dbh, and basal area of sapling regeneration was inversely related to the degree of "overtopping" of residual trees. Black cherry and red maple were the most abundant saplings with 416.5 ± 25.7 and 152.9 ± 16.8 stems per acre, respectively. Models of black...

Genotype and elevation influence Spartina alterniflora colonization and growth in a created salt marsh

USGS Publications Warehouse

Proffitt, C.E.; Travis, S.E.; Edwards, K.R.

2003-01-01

Colonization, growth, and clonal morphology differ with genotype and are influenced by elevation. Local adaptation of Spartina alterniflora to environmental conditions may lead to dominance by different suites of genotypes in different locations within a marsh. In a constructed marsh, we found reduced colonization in terms of density of clones with increasing distance from edge in a 200-ha mudflat created in 1996; however, growth in diameter was not different among three 100-m-long zones that differed in distance from site edge. Distance from edge was confounded by elevation in this comparison of natural colonization. The rate of clonal expansion in diameter was 3.1 m/yr, and clonal growth was linear over the 28 mo of the study. The area dominated by S. alterniflora in the three distance zones increased concomitantly with clonal growth. However, the lower initial clonal densities and colonization by other plant species resulted in reduced overall dominance by S. alterniflora in the two more-interior locations. Seedling recruitment was an important component of S. alterniflora colonization at all elevations and distances from edge two years after site creation. Seedlings were spatially very patchy and tended to occur near clones that probably produced them. A field experiment revealed that S. alterniflora height and total stem length varied with genotype, while stem density and flowering stem density did not. Differences between edge and center of clonal patches also occurred for some response variables, and there were also significant interactions with genotype. Differences between edge and center are interpreted as differences in clone morphology. Elevation differences over distances of a few meters influenced total stem length and flowering stem density but not other response variables. Clones that were larger in diameter also tended to have greater stem heights and total stem lengths. A number of plant morphological measures were found to vary significantly among the five genotypes and had broad-sense heritabilities ranging up to 0.71. These results indicate that S. alterniflora populations developing on new substrata colonize broadly, but growth and reproduction vary with genotype and are influenced by changes in elevation (range: 11.8 cm), and probably other environmental factors, over relatively small distances. Differences in growth and clone morphology of different genets, and the frequent occurrence of seedlings throughout the site, underscore the importance of genetic variability in natural and created populations.

Sheep manure vermicompost supplemented with a native diazotrophic bacteria and mycorrhizas for maize cultivation.

PubMed

Gutiérrez-Miceli, F A; Moguel-Zamudio, B; Abud-Archila, M; Gutiérrez-Oliva, V F; Dendooven, L

2008-10-01

An orthogonal experimental design L9 (3(4)) with 10 repetitions was used to investigate the effect of Glomus claroideum (0, 1 or 2g(-1) plant), G. fasciculatum (0, 1 or 2g plant(-1)), native diazotrophic bacteria (0, 10(3) and 10(5) UFC ml(-1)) and sheep manure vermicompost (0%, 5% and 10% v/v) on maize plant growth, N and P in leaves and mycorrhization percent. Vermicompost explained most of the variation found for leaf number, wet weight, stem height, and diameter. Both mycorrhizas increased the plant wet weight but G. fasciculatum the most. Mycorrhization increased the P content, but not the N content. Mycorrhizal colonization increased when diazotrophic bacteria and vermicompost were added. It was found that weight of maize plants cultivated in peat moss amended with vermicompost increased when supplemented with G. fasciculatum and diazotrophic bacteria.

Quantitative Variation of Flavonoids and Diterpenes in Leaves and Stems of Cistus ladanifer L. at Different Ages.

PubMed

Valares Masa, Cristina; Sosa Díaz, Teresa; Alías Gallego, Juan Carlos; Chaves Lobón, Natividad

2016-02-27

The compounds derived from secondary metabolism in plants perform a variety of ecological functions, providing the plant with resistance to biotic and abiotic factors. The basal levels of these metabolites for each organ, tissue or cell type depend on the development stage of the plant and they may be modified as a response to biotic and/or abiotic stress. As a consequence, the resistance state of a plant may vary in space and time. The secondary metabolites of Cistus ladanifer have been quantified in leaves and stems throughout autumn, winter, spring and summer, and at different ages of the plant. This study shows that there are significant differences between young leaves, mature leaves and stems, and between individuals of different ages. Young leaves show significantly greater synthesis of flavonoids and diterpenes than mature leaves and stems, with a clear seasonal variation, and the differences between leaves at different growth stages and stems is maintained during the quantified seasons. With respect to age, specimens under one year of age secreted significantly lower amounts of compounds. The variation in the composition of secondary metabolites between different parts of the plant, the season and the variations in age may determine the interactions of Cistus ladanifer with the biotic and abiotic factors to which it is exposed.

Needle and stem wood production in Scots pine (Pinus sylvestris) trees of different age, size and competitive status.

PubMed

Vanninen, Petteri; Mäkelä, Annikki

2000-04-01

We studied effects of tree age, size and competitive status on foliage and stem production of 43 Scots pine (Pinus sylvestris L.) trees in southern Finland. The tree attributes related to competition included foliage density, crown ratio and height/diameter ratio. Needle mass was considered to be the primary cause of growth through photosynthesis. Both stem growth and foliage growth were strongly correlated with foliage mass. Consequently, differences in growth allocation between needles and stem wood in trees of different age, size, or position were small. However, increasing relative height increased the sum of stem growth and foliage growth per unit foliage mass, indicating an effect of available light. Suppressed trees seemed to allocate more growth to stem wood than dominant trees, and their stem growth per unit foliage mass was larger. Similarly, trees in dense stands allocated more growth to stem wood than trees in sparse stands. The results conformed to the pipe model theory but seemed to contradict the priority principle of allocation.

Morphologic and morphometric studies of impact craters in the northern plains of Mars

NASA Technical Reports Server (NTRS)

Barlow, N. G.

1993-01-01

Fresh impact craters in the northern plains of Mars display a variety of morphologic and morphometric properties. Ejecta morphologies range from radial to fluidized, interior features include central peaks and central pits, fluidized morphologies display a range of sinuosities, and depth-diameter ratios are being measured to determine regional variations. Studies of the martian northern plains over the past five years have concentrated in three areas: (1) determining correlations of ejecta morphologies with crater diameter, latitude, and underlying terrain; (2) determining variations in fluidized ejecta blanket sinuosity across the planet; and (3) measurement of depth-diameter ratios and determination of regional variations in this ratio.

An individual-based growth and competition model for coastal redwood forest restoration

USGS Publications Warehouse

van Mantgem, Phillip J.; Das, Adrian J.

2014-01-01

Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.

Structure of the Epiphyte Community in a Tropical Montane Forest in SW China

PubMed Central

Zhao, Mingxu; Geekiyanage, Nalaka; Xu, Jianchu; Khin, Myo Myo; Nurdiana, Dian Ridwan; Paudel, Ekananda; Harrison, Rhett Daniel

2015-01-01

Vascular epiphytes are an understudied and particularly important component of tropical forest ecosystems. However, owing to the difficulties of access, little is known about the properties of epiphyte-host tree communities and the factors structuring them, especially in Asia. We investigated factors structuring the vascular epiphyte-host community and its network properties in a tropical montane forest in Xishuangbanna, SW China. Vascular epiphytes were surveyed in six plots located in mature forests. Six host and four micro-site environmental factors were investigated. Epiphyte diversity was strongly correlated with host size (DBH, diameter at breast height), while within hosts the highest epiphyte diversity was in the middle canopy and epiphyte diversity was significantly higher in sites with canopy soil or a moss mat than on bare bark. DBH, elevation and stem height explained 22% of the total variation in the epiphyte species assemblage among hosts, and DBH was the most important factor which alone explained 6% of the variation. Within hosts, 51% of the variation in epiphyte assemblage composition was explained by canopy position and substrate, and the most important single factor was substrate which accounted for 16% of the variation. Analysis of network properties indicated that the epiphyte host community was highly nested, with a low level of epiphyte specialization, and an almost even interaction strength between epiphytes and host trees. Together, these results indicate that large trees harbor a substantial proportion of the epiphyte community in this forest. PMID:25856457

Variations in the size of focal nodular hyperplasia on magnetic resonance imaging.

PubMed

Ramírez-Fuentes, C; Martí-Bonmatí, L; Torregrosa, A; Del Val, A; Martínez, C

2013-01-01

To evaluate the changes in the size of focal nodular hyperplasia (FNH) during long-term magnetic resonance imaging (MRI) follow-up. We reviewed 44 FNHs in 30 patients studied with MRI with at least two MRI studies at least 12 months apart. We measured the largest diameter of the lesion (inmm) in contrast-enhanced axial images and calculated the percentage of variation as the difference between the maximum diameter in the follow-up and the maximum diameter in the initial study. We defined significant variation in size as variation greater than 20%. We also analyzed predisposing hormonal factors. The mean interval between the two imaging studies was 35±2 months (range: 12-94). Most lesions (80%) remained stable during follow-up. Only 9 of the 44 lesions (20%) showed a significant variation in diameter: 7 (16%) decreased in size and 2 (4%) increased, with variations that reached the double of the initial size. The change in size was not related to pregnancy, menopause, or the use of birth control pills or corticoids. Changes in the size of FNHs during follow-up are relatively common and should not lead to a change in the diagnosis. These variations in size seem to be independent of hormonal factors that are considered to predispose. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

Variations in the sonographic measurement techniques of BI-RADS 3 breast masses.

PubMed

Francisco, Juliana; Jales, Rodrigo Menezes; de Oliveira, André Desuó Bueno; Arguello, Carlos Henrique Francisco; Derchain, Sophie

2017-06-01

To evaluate the differences in sonographic (US) distance and volume measurements from different sonologists and identify the optimal parameters to avoid clinically relevant variations in the measurement of BI-RADS 3 breast masses. For this cross-sectional study with prospectively collected data, four physicians with various levels of experience in US, herein called sonologists, performed distance and volume US measurements of 80 masses classified as BI-RADS 3. The Cochran Q test was used to compare the matched sets of rates of clinically relevant variability between all pairs of sonologists' measurements. There were clinically relevant differences between sonologists in the measurements of the longest diameter (range, 17.5-43.7%, p = 0.003), the longest diameter perpendicular to the previous one (anteroposterior diameter) (17.5-33.7%, p = 0.06), the third diameter orthogonal to the plane defined by the previous two (transverse diameter) (28.7-55%, p = 0.001), and at least two of those three diameters (18.7-38.7%, p = 0.015). The smallest clinically relevant differences were observed with volume measurements (range of differences, 6.2-13.7%, p = 0.51). Volume measurement technique was associated with the least variations, whereas distance measurements, which are used routinely, were associated with unacceptable rates of clinically relevant variations. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:252-260, 2017. © 2017 Wiley Periodicals, Inc.

Wood and bark moisture contents of small-diameter hardwoods growing on southern pine sites

Treesearch

F.G. Manwiller

1975-01-01

Ten 6-inch trees from throughout the South were sampled from each of 22 species, of which 11 were oaks. Ranking of species remained constant regardless of whether moisture contents were determined for the entire tree, the stem with bark, branches with bark, or stem- and branchwood without bark. For ashes and hickory, the range among these various components was 46 to...

Rooting stem cuttings of northern red oak (Quercus rubra L.) utilizing hedged stump sprouts formed on recently felled trees

Treesearch

Matthew H. Gocke; Daniel J. Robinson

2010-01-01

The ability to root stem cuttings collected from hedged stump sprouts formed on recently felled trees was evaluated for 26 codominant northern red oak (Quercus rubra L.) trees growing in Durham County, NC. Sprouting occurred, the same year as felling, on 23 of the 26 tree stumps and sprout number was significantly and positively correlated with stump diameter. The...

Wood and bark moisture contents of small-diameter hardwoods growing on southern pine sites

Treesearch

Floyd G. Manwiller

1975-01-01

Ten 6-inch trees from throughout the south were sampled from each of 22 species, of which 11 were oaks. Ranking of species remained constant regardless of whether moisture contents were determined for the entire tree, the stem with bark, branches with bark, or stem- and branchwood without bark. For ashes and hickory, the range among these various components was 46 to...

Developing equations for estimating tree component biomass for naturally regenerated shorteaf pine in southeast Oklahoma with application to biomass partitioning in thinned and unthinned stands

Treesearch

Nabin Gyawali; Thomas B. Lynch; Rodney E. Will

2013-01-01

Traditionally, the main focus of forest production has usually been to maximize allocation of biomass to merchantable stem wood. But the assessment of biomass partitioning in stands is needed to address management concerns such as stem production and allocation, carbon sequestration, wildland fire, whole tree harvesting, etc. Thinning mainly increases the bole diameter...

Changes in forest floor and soil nutrients in a mixed oak forest 33 years after stem only and whole-tree harvest

Treesearch

D.W. Johnson; C.C. Trettin; D.E. Todd

2016-01-01

Vegetation, forest floor, and soils were resampled at a mixed oak site in eastern Tennessee that had been subjected to stem only (SOH), whole-tree harvest (WTH), and no harvest (REF) 33 years previously. Although differences between harvest treatments were not statistically significant (P < 0.05), average diameter, height, basal...

Impact of intra- versus inter-annual snow depth variation on water relations and photosynthesis for two Great Basin Desert shrubs.

PubMed

Loik, Michael E; Griffith, Alden B; Alpert, Holly; Concilio, Amy L; Wade, Catherine E; Martinson, Sharon J

2015-06-01

Snowfall provides the majority of soil water in certain ecosystems of North America. We tested the hypothesis that snow depth variation affects soil water content, which in turn drives water potential (Ψ) and photosynthesis, over 10 years for two widespread shrubs of the western USA. Stem Ψ (Ψ stem) and photosynthetic gas exchange [stomatal conductance to water vapor (g s), and CO2 assimilation (A)] were measured in mid-June each year from 2004 to 2013 for Artemisia tridentata var. vaseyana (Asteraceae) and Purshia tridentata (Rosaceae). Snow fences were used to create increased or decreased snow depth plots. Snow depth on +snow plots was about twice that of ambient plots in most years, and 20 % lower on -snow plots, consistent with several down-scaled climate model projections. Maximal soil water content at 40- and 100-cm depths was correlated with February snow depth. For both species, multivariate ANOVA (MANOVA) showed that Ψ stem, g s, and A were significantly affected by intra-annual variation in snow depth. Within years, MANOVA showed that only A was significantly affected by spatial snow depth treatments for A. tridentata, and Ψ stem was significantly affected by snow depth for P. tridentata. Results show that stem water relations and photosynthetic gas exchange for these two cold desert shrub species in mid-June were more affected by inter-annual variation in snow depth by comparison to within-year spatial variation in snow depth. The results highlight the potential importance of changes in inter-annual variation in snowfall for future shrub photosynthesis in the western Great Basin Desert.

Dissecting variation in biomass conversion factors across China's forests: implications for biomass and carbon accounting.

PubMed

Luo, Yunjian; Zhang, Xiaoquan; Wang, Xiaoke; Ren, Yin

2014-01-01

Biomass conversion factors (BCFs, defined as the ratios of tree components (i.e. stem, branch, foliage and root), as well as aboveground and whole biomass of trees to growing stock volume, Mg m-3) are considered as important parameters in large-scale forest biomass carbon estimation. To date, knowledge of possible sources of the variation in BCFs is still limited at large scales. Using our compiled forest biomass dataset of China, we presented forest type-specific values of BCFs, and examined the variation in BCFs in relation to forest type, stand development and environmental factors (climate and soil fertility). BCFs exhibited remarkable variation across forest types, and also were significantly related to stand development (especially growing stock volume). BCFs (except Stem BCF) had significant relationships with mean annual temperature (MAT) and mean annual precipitation (MAP) (P<0.001). Climatic data (MAT and MAP) collectively explained 10.0-25.0% of the variation in BCFs (except Stem BCFs). Moreover, stronger climatic effects were found on BCFs for functional components (i.e. branch, foliage and root) than BCFs for combined components (i.e. aboveground section and whole trees). A general trend for BCFs was observed to decrease and then increase from low to high soil fertility. When qualitative soil fertility and climatic data (MAT and MAP) were combined, they explained 14.1-29.7% of the variation in in BCFs (except Stem BCFs), adding only 4.1-4.9% than climatic data used. Therefore, to reduce the uncertainty induced by BCFs in forest carbon estimates, we should apply values of BCFs for a specified forest type, and also consider climatic and edaphic effects, especially climatic effect, in developing predictive models of BCFs (except Stem BCF).

Dissecting Variation in Biomass Conversion Factors across China’s Forests: Implications for Biomass and Carbon Accounting

PubMed Central

Wang, Xiaoke; Ren, Yin

2014-01-01

Biomass conversion factors (BCFs, defined as the ratios of tree components (i.e. stem, branch, foliage and root), as well as aboveground and whole biomass of trees to growing stock volume, Mg m−3) are considered as important parameters in large-scale forest biomass carbon estimation. To date, knowledge of possible sources of the variation in BCFs is still limited at large scales. Using our compiled forest biomass dataset of China, we presented forest type-specific values of BCFs, and examined the variation in BCFs in relation to forest type, stand development and environmental factors (climate and soil fertility). BCFs exhibited remarkable variation across forest types, and also were significantly related to stand development (especially growing stock volume). BCFs (except Stem BCF) had significant relationships with mean annual temperature (MAT) and mean annual precipitation (MAP) (P<0.001). Climatic data (MAT and MAP) collectively explained 10.0–25.0% of the variation in BCFs (except Stem BCFs). Moreover, stronger climatic effects were found on BCFs for functional components (i.e. branch, foliage and root) than BCFs for combined components (i.e. aboveground section and whole trees). A general trend for BCFs was observed to decrease and then increase from low to high soil fertility. When qualitative soil fertility and climatic data (MAT and MAP) were combined, they explained 14.1–29.7% of the variation in in BCFs (except Stem BCFs), adding only 4.1–4.9% than climatic data used. Therefore, to reduce the uncertainty induced by BCFs in forest carbon estimates, we should apply values of BCFs for a specified forest type, and also consider climatic and edaphic effects, especially climatic effect, in developing predictive models of BCFs (except Stem BCF). PMID:24728222

Crown characteristics of several coniferous tree species: relations between weight of crown, branchwood and foliage and stem diameter

Treesearch

Theodore G Storey; Wallace L. Fons; F.M. Sauer

1955-01-01

Prediction of wind breakage and uprooting in tree stands requires information on weight of dry crown, branchwood, and foliage. This information has not been published. An experimental program started in 1951 has led to a number of generalized relations by which these crown characteristics can be determined with good accuracy over a wide range of tree diameters, species...

Measurement of oxygen tension within mesenchymal stem cell spheroids.

PubMed

Murphy, Kaitlin C; Hung, Ben P; Browne-Bourne, Stephen; Zhou, Dejie; Yeung, Jessica; Genetos, Damian C; Leach, J Kent

2017-02-01

Spheroids formed of mesenchymal stem cells (MSCs) exhibit increased cell survival and trophic factor secretion compared with dissociated MSCs, making them therapeutically advantageous for cell therapy. Presently, there is no consensus for the mechanism of action. Many hypothesize that spheroid formation potentiates cell function by generating a hypoxic core within spheroids of sufficiently large diameters. The purpose of this study was to experimentally determine whether a hypoxic core is generated in MSC spheroids by measuring oxygen tension in aggregates of increasing diameter and correlating oxygen tension values with cell function. MSC spheroids were formed with 15 000, 30 000 or 60 000 cells per spheroid, resulting in radii of 176 ± 8 µm, 251 ± 12 µm and 353 ± 18 µm, respectively. Oxygen tension values coupled with mathematical modelling revealed a gradient that varied less than 10% from the outer diameter within the largest spheroids. Despite the modest radial variance in oxygen tension, cellular metabolism from spheroids significantly decreased as the number of cells and resultant spheroid size increased. This may be due to adaptive reductions in matrix deposition and packing density with increases in spheroid diameter, enabling spheroids to avoid the formation of a hypoxic core. Overall, these data provide evidence that the enhanced function of MSC spheroids is not oxygen mediated. © 2017 The Author(s).

Effects of trampling on morphological and mechanical traits of dryland shrub species do not depend on water availability.

PubMed

Xu, Liang; Freitas, Sofia M A; Yu, Fei-Hai; Dong, Ming; Anten, Niels P R; Werger, Marinus J A

2013-01-01

In semiarid drylands water shortage and trampling by large herbivores are two factors limiting plant growth and distribution. Trampling can strongly affect plant performance, but little is known about responses of morphological and mechanical traits of woody plants to trampling and their possible interaction with water availability. Seedlings of four shrubs (Caragana intermedia, Cynanchum komarovi, Hedysarum laeve and Hippophae rhamnoides) common in the semiarid Mu Us Sandland were grown at 4% and 10% soil water content and exposed to either simulated trampling or not. Growth, morphological and mechanical traits were measured. Trampling decreased vertical height and increased basal diameter and stem resistance to bending and rupture (as indicated by the increased minimum bend and break force) in all species. Increasing water availability increased biomass, stem length, basal diameter, leaf thickness and rigidity of stems in all species except C. komarovii. However, there were no interactive effects of trampling and water content on any of these traits among species except for minimum bend force and the ratio between stem resistance to rupture and bending. Overall shrub species have a high degree of trampling resistance by morphological and mechanical modifications, and the effects of trampling do not depend on water availability. However, the increasing water availability can also affect trade-off between stem strength and flexibility caused by trampling, which differs among species. Water plays an important role not only in growth but also in trampling adaptation in drylands.

Pathological and immunohistochemical study of lethal primary brain stem injuries

PubMed Central

2012-01-01

Background Many of the deaths that occur shortly after injury or in hospitals are caused by mild trauma. Slight morphological changes are often found in the brain stems of these patients during autopsy. The purpose of this study is to investigate the histopathological changes involved in primary brain stem injuries (PBSI) and their diagnostic significance. Methods A total of 65 patients who had died of PBSI and other conditions were randomly selected. They were divided into 2 groups, an injury group (25 cases) and a control group (20 cases). Slides of each patient’s midbrain, pons, and medulla oblongata were prepared and stained with HE, argentaffin, and immunohistochemical agents (GFAP, NF, amyloid-ß, MBP). Under low power (×100) and NF staining, the diameter of the thickest longitudinal axon was measured at its widest point. Ten such diameters were collected for each part of the brain (midbrain, pons, and medulla oblongata). Data were recorded and analyzed statistically. Results Brain stem contusions, astrocyte activity, edema, and pathological changes in the neurons were visibly different in the injury and control groups (P < 0.05). Characteristic changes occurred in the neural axons, axon diameter varied from axon to axon and even over different segments of one axon, and several pathological phenomena were observed. These included segmental thickening and curving, wave-like processing, disarrangement, and irregular swelling. A few axons ruptured and intumesced into retraction balls. Immunohistochemical MBP staining showed enlargement and curving of spaces between the myelin sheaths and axons in certain areas. The myelin sheaths lining the surfaces of the axons were in some cases incomplete and even exfoliated, and segmentation disappeared. These pathological changes increased in severity over time (P < 0.05). Conclusions These histopathological changes may prove beneficial to the pathological diagnosis of PBSI during autopsy. The measurement of axon diameters provides a referent quantitative index for the diagnosis of the specific causes of death involved in PBSI. Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1345298818712204 PMID:22613041

WEXFORD containment data report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stubbs, T.; Heinle, R.

The WEXFORD event was detonated in hole U2cr of the Nevada Test Site. A plan view map of the local region of hole U2cr showing the surface projections of the faults and the local drill holes is given. The device had a depth-of-burial of 314 m in the Tunnel Beds tuff of Area 2, about 120 m above the standing water level (SWL). Stemming of the 2.44 m diameter emplacement hole followed the plan. A log of the stemming operations was maintained by Holmes and Narver. Detonation time was 07:45 PDT on August 30, 1984 and about 26 minutes latermore » the chimney collapsed to the surface leaving a small, off-center crater which grew, over several days, until it took on a cookie cutter form encompassing the emplacement hole and having a mean diameter of about 35 m. An interior, highly asymmetric crater had a mean diameter of about 12 m. No functioning monitors detected radiation arrivals in the emplacement hole above a depth of 130 m and the WEXFORD containment was considered successful.« less

Multiple loci and genetic interactions involving flowering time genes regulate stem branching among natural variants of Arabidopsis.

PubMed

Huang, Xueqing; Ding, Jia; Effgen, Sigi; Turck, Franziska; Koornneef, Maarten

2013-08-01

Shoot branching is a major determinant of plant architecture. Genetic variants for reduced stem branching in the axils of cauline leaves of Arabidopsis were found in some natural accessions and also at low frequency in the progeny of multiparent crosses. Detailed genetic analysis using segregating populations derived from backcrosses with the parental lines and bulked segregant analysis was used to identify the allelic variation controlling reduced stem branching. Eight quantitative trait loci (QTLs) contributing to natural variation for reduced stem branching were identified (REDUCED STEM BRANCHING 1-8 (RSB1-8)). Genetic analysis showed that RSB6 and RSB7, corresponding to flowering time genes FLOWERING LOCUS C (FLC) and FRIGIDA (FRI), epistatically regulate stem branching. Furthermore, FLOWERING LOCUS T (FT), which corresponds to RSB8 as demonstrated by fine-mapping, transgenic complementation and expression analysis, caused pleiotropic effects not only on flowering time, but, in the specific background of active FRI and FLC alleles, also on the RSB trait. The consequence of allelic variation only expressed in late-flowering genotypes revealed novel and thus far unsuspected roles of several genes well characterized for their roles in flowering time control. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Response of Organ Structure and Physiology to Autotetraploidization in Early Development of Energy Willow Salix viminalis.

PubMed

Dudits, Dénes; Török, Katalin; Cseri, András; Paul, Kenny; Nagy, Anna V; Nagy, Bettina; Sass, László; Ferenc, Györgyi; Vankova, Radomira; Dobrev, Petre; Vass, Imre; Ayaydin, Ferhan

2016-03-01

The biomass productivity of the energy willow Salix viminalis as a short-rotation woody crop depends on organ structure and functions that are under the control of genome size. Colchicine treatment of axillary buds resulted in a set of autotetraploid S. viminalis var. Energo genotypes (polyploid Energo [PP-E]; 2n = 4x = 76) with variation in the green pixel-based shoot surface area. In cases where increased shoot biomass was observed, it was primarily derived from larger leaf size and wider stem diameter. Autotetraploidy slowed primary growth and increased shoot diameter (a parameter of secondary growth). The duplicated genome size enlarged bark and wood layers in twigs sampled in the field. The PP-E plants developed wider leaves with thicker midrib and enlarged palisade parenchyma cells. Autotetraploid leaves contained significantly increased amounts of active gibberellins, cytokinins, salicylic acid, and jasmonate compared with diploid individuals. Greater net photosynthetic CO2 uptake was detected in leaves of PP-E plants with increased chlorophyll and carotenoid contents. Improved photosynthetic functions in tetraploids were also shown by more efficient electron transport rates of photosystems I and II. Autotetraploidization increased the biomass of the root system of PP-E plants relative to diploids. Sections of tetraploid roots showed thickening with enlarged cortex cells. Elevated amounts of indole acetic acid, active cytokinins, active gibberellin, and salicylic acid were detected in the root tips of these plants. The presented variation in traits of tetraploid willow genotypes provides a basis to use autopolyploidization as a chromosome engineering technique to alter the organ development of energy plants in order to improve biomass productivity. © 2016 American Society of Plant Biologists. All Rights Reserved.

Response of Organ Structure and Physiology to Autotetraploidization in Early Development of Energy Willow Salix viminalis1

PubMed Central

Dudits, Dénes; Török, Katalin; Cseri, András; Paul, Kenny; Nagy, Bettina; Sass, László; Ferenc, Györgyi; Vankova, Radomira; Dobrev, Petre; Vass, Imre; Ayaydin, Ferhan

2016-01-01

The biomass productivity of the energy willow Salix viminalis as a short-rotation woody crop depends on organ structure and functions that are under the control of genome size. Colchicine treatment of axillary buds resulted in a set of autotetraploid S. viminalis var. Energo genotypes (polyploid Energo [PP-E]; 2n = 4x = 76) with variation in the green pixel-based shoot surface area. In cases where increased shoot biomass was observed, it was primarily derived from larger leaf size and wider stem diameter. Autotetraploidy slowed primary growth and increased shoot diameter (a parameter of secondary growth). The duplicated genome size enlarged bark and wood layers in twigs sampled in the field. The PP-E plants developed wider leaves with thicker midrib and enlarged palisade parenchyma cells. Autotetraploid leaves contained significantly increased amounts of active gibberellins, cytokinins, salicylic acid, and jasmonate compared with diploid individuals. Greater net photosynthetic CO2 uptake was detected in leaves of PP-E plants with increased chlorophyll and carotenoid contents. Improved photosynthetic functions in tetraploids were also shown by more efficient electron transport rates of photosystems I and II. Autotetraploidization increased the biomass of the root system of PP-E plants relative to diploids. Sections of tetraploid roots showed thickening with enlarged cortex cells. Elevated amounts of indole acetic acid, active cytokinins, active gibberellin, and salicylic acid were detected in the root tips of these plants. The presented variation in traits of tetraploid willow genotypes provides a basis to use autopolyploidization as a chromosome engineering technique to alter the organ development of energy plants in order to improve biomass productivity. PMID:26729798

Assessing the Potential of Low-Cost 3D Cameras for the Rapid Measurement of Plant Woody Structure

PubMed Central

Nock, Charles A; Taugourdeau, Olivier; Delagrange, Sylvain; Messier, Christian

2013-01-01

Detailed 3D plant architectural data have numerous applications in plant science, but many existing approaches for 3D data collection are time-consuming and/or require costly equipment. Recently, there has been rapid growth in the availability of low-cost, 3D cameras and related open source software applications. 3D cameras may provide measurements of key components of plant architecture such as stem diameters and lengths, however, few tests of 3D cameras for the measurement of plant architecture have been conducted. Here, we measured Salix branch segments ranging from 2–13 mm in diameter with an Asus Xtion camera to quantify the limits and accuracy of branch diameter measurement with a 3D camera. By scanning at a variety of distances we also quantified the effect of scanning distance. In addition, we also test the sensitivity of the program KinFu for continuous 3D object scanning and modeling as well as other similar software to accurately record stem diameters and capture plant form (<3 m in height). Given its ability to accurately capture the diameter of branches >6 mm, Asus Xtion may provide a novel method for the collection of 3D data on the branching architecture of woody plants. Improvements in camera measurement accuracy and available software are likely to further improve the utility of 3D cameras for plant sciences in the future. PMID:24287538

The Role of Aspirational Experiences and Behaviors in Cultivating Momentum for Transfer Access in STEM: Variations across Gender and Race

ERIC Educational Resources Information Center

Wang, Xueli; Lee, Seo Young; Prevost, Amy

2017-01-01

Objective: Although upward transfer in science, technology, engineering, and mathematics (STEM) fields represents a prominent national policy concern, community college students' aspirations for transfer in STEM are often impeded, resulting in lower transfer rates. This study investigated four aspects of community college STEM students'…

7 CFR 51.1565 - Internal defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., Internal Discoloration, Vascular Browning, Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5... Discoloration (Heat Necrosis) Not more than the equivalent of 3 scattered spots 1/8 inch in diameter in a potato...

7 CFR 51.1565 - Internal defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., Internal Discoloration, Vascular Browning, Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5... Discoloration (Heat Necrosis) Not more than the equivalent of 3 scattered spots 1/8 inch in diameter in a potato...

The woody biomass resource of Tennessee, 1989

Treesearch

James F. Rosson

1993-01-01

Tabulates fresh and dry biomass estimates of major trees in Tennessee by forest type, ownership, species, stand basal area, tree class, diameter, and height. Information is presented for total tree, stem, and crown components.

7 CFR 923.10 - Size.

Code of Federal Regulations, 2010 CFR

2010-01-01

... IN WASHINGTON Order Regulating Handling Definitions § 923.10 Size. Size means the greatest diameter, measured through the center of the cherry, at right angles to a line running from the stem to the blossom...

7 CFR 923.10 - Size.

Code of Federal Regulations, 2012 CFR

2012-01-01

... IN WASHINGTON Order Regulating Handling Definitions § 923.10 Size. Size means the greatest diameter, measured through the center of the cherry, at right angles to a line running from the stem to the blossom...

7 CFR 922.10 - Size.

Code of Federal Regulations, 2010 CFR

2010-01-01

... WASHINGTON Order Regulating Handling Definitions § 922.10 Size. Size means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom end, or...

7 CFR 922.10 - Size.

Code of Federal Regulations, 2013 CFR

2013-01-01

... WASHINGTON Order Regulating Handling Definitions § 922.10 Size. Size means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom end, or...

7 CFR 922.10 - Size.

Code of Federal Regulations, 2012 CFR

2012-01-01

... WASHINGTON Order Regulating Handling Definitions § 922.10 Size. Size means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom end, or...

7 CFR 923.10 - Size.

Code of Federal Regulations, 2013 CFR

2013-01-01

... IN WASHINGTON Order Regulating Handling Definitions § 923.10 Size. Size means the greatest diameter, measured through the center of the cherry, at right angles to a line running from the stem to the blossom...

7 CFR 922.10 - Size.

Code of Federal Regulations, 2014 CFR

2014-01-01

... WASHINGTON Order Regulating Handling Definitions § 922.10 Size. Size means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom end, or...

7 CFR 922.10 - Size.

Code of Federal Regulations, 2011 CFR

2011-01-01

... WASHINGTON Order Regulating Handling Definitions § 922.10 Size. Size means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the blossom end, or...

7 CFR 923.10 - Size.

Code of Federal Regulations, 2011 CFR

2011-01-01

... IN WASHINGTON Order Regulating Handling Definitions § 923.10 Size. Size means the greatest diameter, measured through the center of the cherry, at right angles to a line running from the stem to the blossom...

7 CFR 923.10 - Size.

Code of Federal Regulations, 2014 CFR

2014-01-01

... IN WASHINGTON Order Regulating Handling Definitions § 923.10 Size. Size means the greatest diameter, measured through the center of the cherry, at right angles to a line running from the stem to the blossom...

The woody biomass resource of Louisiana, 1991

Treesearch

James F. Rosson

1993-01-01

Tabulates fresh and dry biomass estimates of major trees in Louisiana by forest type, ownership, species, stand basal area, tree class, diameter, and height. Information is presented for total tree, stem, and crown components.

Ecological effects of pipeline construction through deciduous forested wetlands, Midland County, Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zellmer, S.D.; Rastorfer, J.R.; Van Dyke, G.D.

Implementation of recent federal and state regulations promulgated to protect wetlands makes information on effects of gas pipeline rights-of-way (ROWs) in wetlands essential to the gas pipeline industry. This study is designed to record vegetational changes induced by the construction of a large-diameter gas pipeline through deciduous forested wetlands. Two second-growth forested wetland sites mapped as Lenawee soils, one mature and one subjected to recent selective logging, were selected in Midland County, Michigan. Changes in the adjacent forest and successional development on the ROW are being documented. Cover-class estimates are being made for understory and ROW plant species using 1more » {times}1-m quadrats. Counts are also being made for all woody species with stems < 2 cm in diameter at breast height (dbh) in the same plots used for cover-class estimates. Individual stem diameters and species counts are being recorded for all woody understory and overstory plants with stems {ge}2 cm dbh in 10 {times} 10-m plots. Although analyses of the data have not been completed, preliminary analyses indicate that some destruction of vegetation at the ROW forest edge may have been avoidable during pipeline construction. Rapid regrowth of many native wetland plant species on the ROW occurred because remnants of native vegetation and soil-bearing propagules of existing species survived on the ROW after pipeline construction and seeding operations. 91 refs., 11 figs., 3 tabs.« less

Diurnal and seasonal changes in stem increment and water use by yellow poplar trees in response to environmental stress.

PubMed

McLaughlin, Samuel B; Wullschleger, Stan D; Nosal, Miloslav

2003-11-01

To evaluate indicators of whole-tree physiological responses to climate stress, we determined seasonal, daily and diurnal patterns of growth and water use in 10 yellow poplar (Liriodendron tulipifera L.) trees in a stand recently released from competition. Precise measurements of stem increment and sap flow made with automated electronic dendrometers and thermal dissipation probes, respectively, indicated close temporal linkages between water use and patterns of stem shrinkage and swelling during daily cycles of water depletion and recharge of extensible outer-stem tissues. These cycles also determined net daily basal area increment. Multivariate regression models based on a 123-day data series showed that daily diameter increments were related negatively to vapor pressure deficit (VPD), but positively to precipitation and temperature. The same model form with slight changes in coefficients yielded coefficients of determination of about 0.62 (0.57-0.66) across data subsets that included widely variable growth rates and VPDs. Model R2 was improved to 0.75 by using 3-day running mean daily growth data. Rapid recovery of stem diameter growth following short-term, diurnal reductions in VPD indicated that water stored in extensible stem tissues was part of a fast recharge system that limited hydration changes in the cambial zone during periods of water stress. There were substantial differences in the seasonal dynamics of growth among individual trees, and analyses indicated that faster-growing trees were more positively affected by precipitation, solar irradiance and temperature and more negatively affected by high VPD than slower-growing trees. There were no negative effects of ozone on daily growth rates in a year of low ozone concentrations.

Nursery Cultural Practices and Morphological Attributes of Longleaf Pine Bare-Root Stock as Indicators of Early Field Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glyndon E. Hatchell, Research Forester, Retired Institute for Mycorrhizal Research and Development Athens, Georgia and H. David Muse, Professor Department of Mathematics University of North Alabama Florence, Alabama

1990-02-01

A large study of morphological attributes of longleaf pine nursery stock at the Savannah River site of the various attributes measured, only number of lateral roots and seedling diameters were related to performance. Lateral root pruning in the nursery also improved performance. Both survival and growth during the first two years were strongly correlated with larger stem diameter and larger root system development.

Influence of crown class, diameter, and sprout rank on red maple (Acer rubrum L.) development during forest succession in Connecticut

Treesearch

Jeffery S. Ward; George R. Stephens

1993-01-01

Crown class, stem diameter, and sprout rank of 2067 red maples on medium quality sites were measured at 10-yr intervals between 1927-1987. Nominal stand age was 25 yrs in 1927. There was a progressive increase in the probability of an individual red maple ascending into the upper canopy and persisting in the upper canopy from suppressed through dominant crown classes...

Using induced pluripotent stem cells to explore genetic and epigenetic variation associated with Alzheimer's disease.

PubMed

Imm, Jennifer; Kerrigan, Talitha L; Jeffries, Aaron; Lunnon, Katie

2017-11-01

It is thought that both genetic and epigenetic variation play a role in Alzheimer's disease initiation and progression. With the advent of somatic cell reprogramming into induced pluripotent stem cells it is now possible to generate patient-derived cells that are able to more accurately model and recapitulate disease. Furthermore, by combining this with recent advances in (epi)genome editing technologies, it is possible to begin to examine the functional consequence of previously nominated genetic variants and infer epigenetic causality from recently identified epigenetic variants. In this review, we explore the role of genetic and epigenetic variation in Alzheimer's disease and how the functional relevance of nominated loci can be investigated using induced pluripotent stem cells and (epi)genome editing techniques.

Statistical variability study of random dopant fluctuation on gate-all-around inversion-mode silicon nanowire field-effect transistors

NASA Astrophysics Data System (ADS)

Yoon, Jun-Sik; Rim, Taiuk; Kim, Jungsik; Kim, Kihyun; Baek, Chang-Ki; Jeong, Yoon-Ha

2015-03-01

Random dopant fluctuation effects of gate-all-around inversion-mode silicon nanowire field-effect transistors (FETs) with different diameters and extension lengths are investigated. The nanowire FETs with smaller diameter and longer extension length reduce average values and variations of subthreshold swing and drain-induced barrier lowering, thus improving short channel immunity. Relative variations of the drain currents increase as the diameter decreases because of decreased current drivability from narrower channel cross-sections. Absolute variations of the drain currents decrease critically as the extension length increases due to decreasing the number of arsenic dopants penetrating into the channel region. To understand variability origins of the drain currents, variations of source/drain series resistance and low-field mobility are investigated. All these two parameters affect the variations of the drain currents concurrently. The nanowire FETs having extension lengths sufficient to prevent dopant penetration into the channel regions and maintaining relatively large cross-sections are suggested to achieve suitable short channel immunity and small variations of the drain currents.

Bias of cylinder diameter estimation from ground-based laser scanners with different beam widths: A simulation study

NASA Astrophysics Data System (ADS)

Forsman, Mona; Börlin, Niclas; Olofsson, Kenneth; Reese, Heather; Holmgren, Johan

2018-01-01

In this study we have investigated why diameters of tree stems, which are approximately cylindrical, are often overestimated by mobile laser scanning. This paper analyzes the physical processes when using ground-based laser scanning that may contribute to a bias when estimating cylinder diameters using circle-fit methods. A laser scanner simulator was implemented and used to evaluate various properties, such as distance, cylinder diameter, and beam width of a laser scanner-cylinder system to find critical conditions. The simulation results suggest that a positive bias of the diameter estimation is expected. Furthermore, the bias follows a quadratic function of one parameter - the relative footprint, i.e., the fraction of the cylinder width illuminated by the laser beam. The quadratic signature opens up a possibility to construct a compensation model for the bias.

High endemism and stem density distinguish New Caledonian from other high-diversity rainforests in the Southwest Pacific.

PubMed

Ibanez, Thomas; Blanchard, E; Hequet, V; Keppel, G; Laidlaw, M; Pouteau, R; Vandrot, H; Birnbaum, P

2018-01-25

The biodiversity hotspot of New Caledonia is globally renowned for the diversity and endemism of its flora. New Caledonia's tropical rainforests have been reported to have higher stem densities, higher concentrations of relictual lineages and higher endemism than other rainforests. This study investigates whether these aspects differ in New Caledonian rainforests compared to other high-diversity rainforests in the Southwest Pacific. Plants (with a diameter at breast height ≥10 cm) were surveyed in nine 1-ha rainforest plots across the main island of New Caledonia and compared with 14 1-ha plots in high-diversity rainforests of the Southwest Pacific (in Australia, Fiji, Papua New Guinea and the Solomon Islands). This facilitated a comparison of stem densities, taxonomic composition and diversity, and species turnover among plots and countries. The study inventoried 11 280 stems belonging to 335 species (93 species ha-1 on average) in New Caledonia. In comparison with other rainforests in the Southwest Pacific, New Caledonian rainforests exhibited higher stem density (1253 stems ha-1 on average) including abundant palms and tree ferns, with the high abundance of the latter being unparalleled outside New Caledonia. In all plots, the density of relictual species was ≥10 % for both stems and species, with no discernible differences among countries. Species endemism, reaching 89 % on average, was significantly higher in New Caledonia. Overall, species turnover increased with geographical distance, but not among New Caledonian plots. High stem density, high endemism and a high abundance of tree ferns with stem diameters ≥10 cm are therefore unique characteristics of New Caledonian rainforests. High endemism and high spatial species turnover imply that the current system consisting of a few protected areas is inadequate, and that the spatial distribution of plant species needs to be considered to adequately protect the exceptional flora of New Caledonian rainforests. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Recruitment variation of crappies in response to hydrology of Tennessee reservoirs

USGS Publications Warehouse

Sammons, S.M.; Bettoli, P.W.; Isermann, D.A.; Churchill, T.N.

2002-01-01

Black crappies Pomoxis nigromaculatus and white crappies P. annularis were sampled to index recruitment in seven Tennessee reservoirs (four main-stem and three tributary storage impoundments). Crappie recruitment in tributary storage impoundments appeared to be consistently higher in years of high discharge during the prespawn period (1 January-31 March). A similar relation was found in one main-stem impoundment; however, crappie recruitment in two main-stem impoundments was inversely related to discharge during the spawning period (1 April-30 May), and little recruitment variation was found in the fourth main-stem impoundment. In general, reservoir hydrology appeared to have a stronger effect on crappie recruitment in tributary storage impoundments than in main-stem impoundments, possibly because recruitment was more variable in tributary systems. Thus, it is likely that crappie populations will rarely have strong year-classes simultaneously over a wide geographic area or even within a single watershed.

7 CFR 51.3416 - Classification of defects.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5% waste 10% waste. Occurring entirely... discoloration (Heat Necrosis) Not more than the equivalent of 3 scattered spots 1/8 inch in diameter in a potato...

7 CFR 51.3416 - Classification of defects.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5% waste 10% waste. Occurring entirely... discoloration (Heat Necrosis) Not more than the equivalent of 3 scattered spots 1/8 inch in diameter in a potato...

Monitoring of vegetation response to elk population and habitat management in Rocky Mountain National Park, 2008–14

USGS Publications Warehouse

Zeigenfuss, Linda C.; Johnson, Therese L.

2015-12-17

Increases in the number of small-diameter, tree-sized (stems greater than 2.5 meter height) aspen stems were observed but only inside fences that excluded ungulates. In unfenced areas, stand structure was stagnant, with many medium- and large-diameter (older) stems and no replacement of small-diameter stems. By 2013, aspen saplings (stems less than or equal to 2.5 meter height) were recruiting on 29 percent of sampled sites, an increase from 13 percent of sites at baseline, but this was mainly due to growth inside fences. Upland herbaceous offtake dropped below baseline levels (61 percent) on both core and noncore winter range in 2010–14. Less than 10 percent of the upland areas had intense herbivory (greater than 85 percent offtake), and less than 30 percent of the landscape had offtake greater than 70 percent after 2009. Offtake levels in 2013 and 2014 indicated an increase in grazing pressure on upland sites compared to 2010–12 levels, but this change may have been in response to loss of large patches of both herbaceous and woody forage in Moraine Park following the 2012 Fern Lake Fire. Winter willow offtake remained steady from 2009 to 2014, and although there were no substantial increases in offtake, there were also no consistent declines. Winter-range willow offtake was below the baseline level of 35 percent only in 2013 and 2014. Willow heights have stayed at or above baseline levels of 0.9 meter. Average heights of willow increased compared to baseline measures within fenced habitat on the core winter range and on noncore (all unfenced) winter range. Willow cover increased at least 75 percent compared to baseline within core winter-range fenced areas and roughly 25 percent in noncore winter range. Overall, during the first 5 years of implementation, the EVMP at Rocky Mountain National Park seems to be making steady progress toward the vegetation objectives set out by the EVMP. Habitat fencing has been the most effective means of improving aspen and willow habitat conditions.

(15)N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods.

PubMed

van der Sleen, Peter; Vlam, Mart; Groenendijk, Peter; Anten, Niels P R; Bongers, Frans; Bunyavejchewin, Sarayudh; Hietz, Peter; Pons, Thijs L; Zuidema, Pieter A

2015-01-01

Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated (15)N abundance (δ(15)N) in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of (15)N-depleted nitrate from the soil, following anthropogenic nitrogen deposition over the last decades. To find further evidence for altered nitrogen cycling in tropical forests, we measured long-term δ(15)N values in trees from Bolivia, Cameroon, and Thailand. We used two different sampling methods. In the first, wood samples were taken in a conventional way: from the pith to the bark across the stem of 28 large trees (the "radial" method). In the second, δ(15)N values were compared across a fixed diameter (the "fixed-diameter" method). We sampled 400 trees that differed widely in size, but measured δ(15)N in the stem around the same diameter (20 cm dbh) in all trees. As a result, the growth rings formed around this diameter differed in age and allowed a comparison of δ(15)N values over time with an explicit control for potential size-effects on δ(15)N values. We found a significant increase of tree-ring δ(15)N across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring δ(15)N values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of δ(15)N values within trees reflect tree ontogeny (size development). However, for the trees from Cameroon and Thailand, a low statistical power in the fixed-diameter method prevents to conclude this with high certainty. For the trees from Bolivia, statistical power in the fixed-diameter method was high, showing that the temporal trend in tree-ring δ(15)N values in the radial method is primarily caused by tree ontogeny and unlikely by a change in nitrogen cycling. We therefore stress to account for tree size before tree-ring δ(15)N values can be properly interpreted.

Historical early stem development of northern white-cedar (Thuja occidentalis L.) in Maine

Treesearch

Philip V. Hofmeyer; Laura S. Kenefic; Robert S. Seymour

2010-01-01

We used stem analysis to quantify early height and diameter growth rates of 80 northern white-cedar trees (17.4-55.0 cm dbh) harvested in 2005 and 2006 in central and northern Maine. It took an average of 42 years (range, 9-86 years) for sampled trees to grow from stump height to sapling size, 96 years to grow to pole size (range, 28-171), 140 years to grow to...

Status and Trend of Cottonwood Forests Along the Missouri River

DTIC Science & Technology

2010-03-03

Woody stem density (#/ha) in the shrub layer was estimated by counting all individual shrubs , saplings, and woody vines found within the sampling... shrubs (or saplings and woody vines ) that intercepted the vertical plane of the plot centerline above 1 m off the ground. We noted the total distance...tree measured had a liana ( woody vine ) growing on its trunk. Because many or most of the cottonwoods in sapling and pole stands had stem diameters

Development of Paper Products from Dried Sweetpotato Stems and Peanut Shells

NASA Technical Reports Server (NTRS)

McConnell, R.; Smith, R.; Jones, G.; Lu, J. Y.

1998-01-01

One of the goals of NASA's Advanced Life Support Program (ALS) for sustaining human life in space is to achieve a closed system in plant production and usage. That all inedible plant parts should be recycled or used in some way. A Tuskegee University team researching sweetpotato and peanut for ALS has developed paper products from dried sweet-potato stems and peanut shells. In this study, the sweet-potato stems and peanut shells were soaked separately in water for 48 hours. After 48 hours, researchers manually separated the pulp and the unusable parts. To form the paper, 160 g of pulp and water mixture was poured through a 15.1 cm (diameter) filtration funnel and the pulp was trapped on 15 cm (diameter) filter paper. The filter paper and pulp were dried in an air oven, and the filter paper was removed, An examination under a scanning electron microscope showed that the sweet-potato paper was composed of "fibers", whereas the peanut shell paper was composed of "blocks". Results of physical testing showed that the sweet-potato stem paper was stronger than the peanut shell paper. It is anticipated that there may be other uses of these products such as writing paper, bags and packaging material. Because of its biodegradability, it can be incorporated into the resource recycling system at the end of its use.

Magnitude of cement-device interfacial stresses with and without tibial stemming: impact of BMI.

PubMed

Gopalakrishnan, Ananthkrishnan; Hedley, Anthony Keith; Kester, Mark A

2011-03-01

Patients expect their total knee arthroplasty to relieve pain and to be long lasting. With patients becoming more active, weighing more, and living longer, this expectation becomes increasingly more difficult to fulfill. Patients who are obese and active put greater loads on their implants and may have a greater risk of failure. Although much attention has been paid to decreasing polyethylene wear, a major cause of implant failure, very little research focus has been directed to elucidate other measures to reduce failure, such as the efficacy of prophylactic stemming of the tibial tray. This study explored whether additional mechanical support for tibial base plates would help reduce bone cement stresses in heavy patients, who, like patients with a high activity level, put added stress on their implants. A tibial base plate with a 12-mm-diameter x 50-mm-long stem was compared with the same tibial base plate with a 15-mm-diameter x 20-mm-long end cap using finite element analysis. The results indicate that the tibial base plate with a prophylactic stem significantly reduced compressive and shear stresses on the cement-device interface and therefore may help to reduce the possibility of tibial loosening in these at-risk patients. Further, such studies will aid the surgeon in educating patients and in selecting the appropriate implant strategy.

How trees allocate carbon for optimal growth: insight from a game-theoretic model.

PubMed

Fu, Liyong; Sun, Lidan; Han, Hao; Jiang, Libo; Zhu, Sheng; Ye, Meixia; Tang, Shouzheng; Huang, Minren; Wu, Rongling

2017-02-01

How trees allocate photosynthetic products to primary height growth and secondary radial growth reflects their capacity to best use environmental resources. Despite substantial efforts to explore tree height-diameter relationship empirically and through theoretical modeling, our understanding of the biological mechanisms that govern this phenomenon is still limited. By thinking of stem woody biomass production as an ecological system of apical and lateral growth components, we implement game theory to model and discern how these two components cooperate symbiotically with each other or compete for resources to determine the size of a tree stem. This resulting allometry game theory is further embedded within a genetic mapping and association paradigm, allowing the genetic loci mediating the carbon allocation of stemwood growth to be characterized and mapped throughout the genome. Allometry game theory was validated by analyzing a mapping data of stem height and diameter growth over perennial seasons in a poplar tree. Several key quantitative trait loci were found to interpret the process and pattern of stemwood growth through regulating the ecological interactions of stem apical and lateral growth. The application of allometry game theory enables the prediction of the situations in which the cooperation, competition or altruism is an optimal decision of a tree to fully use the environmental resources it owns. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Implication of femoral stem on performance of articular surface replacement (ASR) XL total hip arthroplasty.

PubMed

Cip, Johannes; von Strempel, Archibald; Bach, Christian; Luegmair, Matthias; Benesch, Thomas; Martin, Arno

2014-11-01

Taper junctions of large diameter metal-on-metal femoral heads and femoral stems were described as metal ion generator due to accelerated wear and corrosion. However, literature about the Articular Surface Replacement (ASR) total hip arthroplasty (THA) invariably deals with stems manufactured by DePuy Orthopedics (Warsaw, IN, USA). Nothing is known whether different stems with common 12/14 mm tapers affect failure rate or ion release. 99 ASR THA (88 patients) implanted with CoxaFit or ARGE Geradschaft stems (K-Implant, Hannover, Germany) were retrospectively analyzed. After a mean follow-up of 3.5 years revision rate was 24.5%, mostly due to adverse reaction to metal debris (ARMD). CT scan revealed component loosening in 10.3% and pseudotumoral lesions in 12.6%. Elevated ion concentrations (>7 μg/l) were found in 38.6%. Copyright © 2014 Elsevier Inc. All rights reserved.

Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA

USGS Publications Warehouse

van Wagtendonk, J.W.; Moore, P.E.

2010-01-01

Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m-2 year-1 in small diameter mountain hemlock stands to ???300 g m-2 year-1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m-2 year-1 for small diameter stands of Jeffrey pine to 126.9 g m-2 year-1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to estimate fuel treatment longevity, assist in determining fuel model transitions, and predict future changes in fuel bed characteristics.

Biophysical modelling of intra-ring variations in tracheid features and wood density of Pinus pinaster trees exposed to seasonal droughts.

PubMed

Wilkinson, Sarah; Ogée, Jérôme; Domec, Jean-Christophe; Rayment, Mark; Wingate, Lisa

2015-03-01

Process-based models that link seasonally varying environmental signals to morphological features within tree rings are essential tools to predict tree growth response and commercially important wood quality traits under future climate scenarios. This study evaluated model portrayal of radial growth and wood anatomy observations within a mature maritime pine (Pinus pinaster (L.) Aït.) stand exposed to seasonal droughts. Intra-annual variations in tracheid anatomy and wood density were identified through image analysis and X-ray densitometry on stem cores covering the growth period 1999-2010. A cambial growth model was integrated with modelled plant water status and sugar availability from the soil-plant-atmosphere transfer model MuSICA to generate estimates of cell number, cell volume, cell mass and wood density on a weekly time step. The model successfully predicted inter-annual variations in cell number, ring width and maximum wood density. The model was also able to predict the occurrence of special anatomical features such as intra-annual density fluctuations (IADFs) in growth rings. Since cell wall thickness remained surprisingly constant within and between growth rings, variations in wood density were primarily the result of variations in lumen diameter, both in the model and anatomical data. In the model, changes in plant water status were identified as the main driver of the IADFs through a direct effect on cell volume. The anatomy data also revealed that a trade-off existed between hydraulic safety and hydraulic efficiency. Although a simplified description of cambial physiology is presented, this integrated modelling approach shows potential value for identifying universal patterns of tree-ring growth and anatomical features over a broad climatic gradient. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Adjusting the Stems Regional Forest Growth Model to Improve Local Predictions

Treesearch

W. Brad Smith

1983-01-01

A simple procedure using double sampling is described for adjusting growth in the STEMS regional forest growth model to compensate for subregional variations. Predictive accuracy of the STEMS model (a distance-independent, individual tree growth model for Lake States forests) was improved by using this procedure

Probing plasmon resonances of individual aluminum nanoparticles

NASA Astrophysics Data System (ADS)

Wei, Zhongxia; Mao, Peng; Cao, Lu; Song, Fengqi

2018-01-01

The plasmon resonances of individual aluminum nanoparticles are investigated by electron energy-loss spectroscopy (EELS) in scanning transmission electron microscope (STEM). Surface plasmon mode and bulk plasmon mode of Al nanoparticles are clearly characterized in the EEL spectra. Discrete dipole approximation (DDA) calculations show that as the particle diameter increases from 20 nm to 100 nm, the plasmon resonance shifts to lower energy and higher mode of surface plasmon arises when the diameter reaches 60 nm and larger.

[Are Higher Prices for Larger Femoral Heads in Total Hip Arthroplasty Justified from the Perspective of Health Care Economics? An Analysis of Costs and Effects in Germany].

PubMed

Grunert, R; Schleifenbaum, S; Möbius, R; Sommer, G; Zajonz, D; Hammer, N; Prietzel, T

2017-02-01

Background: In total hip arthroplasty (THA), femoral head diameter has not been regarded as a key parameter which should be restored when reconstructing joint biomechanics and geometry. Apart from the controversial discussion on the advantages and disadvantages of using larger diameter heads, their higher cost is another important reason that they have only been used to a limited extent. The goal of this study was to analyse the price structure of prosthetic heads in comparison to other components used in THA. A large group of patients with hip endoprostheses were evaluated with respect to the implanted socket diameter and thus the theoretically attainable head diameter. Materials and Methods: The relative prices of various THA components (cups, inserts, stems and ball heads) distributed by two leading German manufacturers were determined and analysed. Special attention was paid to different sizes and varieties in a series of components. A large patient population treated with THA was evaluated with respect to the implanted cup diameter and therefore the theoretically attainable head diameter. Results: The pricing analysis of the THA components of two manufacturers showed identical prices for cups, inserts and stems in a series. In contrast to this, the prices for prosthetic heads with a diameter of 36-44 mm were 11-50 % higher than for 28 mm heads. Identical prices for larger heads were the exception. The distribution of the head diameter in 2719 THA cases showed significant differences between the actually implanted and the theoretically attainable heads. Conclusion: There are proven advantages in using larger diameter ball heads in THA and the remaining problems can be solved. It is therefore desirable to correct the current pricing practice of charging higher prices for larger components. Instead, identical prices should be charged for all head diameters in a series, as is currently established practice for all other THA components. Thus when reconstructing biomechanics and joint geometry in THA, it should be possible to recover not only leg length, femoral offset and antetorsion of the femoral neck, but also to approximately restore the diameter of the femoral head and thereby optimise the functional outcome. Georg Thieme Verlag KG Stuttgart · New York.

Novel population of small tumour-initiating stem cells in the ovaries of women with borderline ovarian cancer

PubMed Central

Virant-Klun, Irma; Stimpfel, Martin

2016-01-01

Small stem cells with diameters of up to 5 μm previously isolated from adult human ovaries indicated pluripotency and germinal lineage, especially primordial germ cells, and developed into primitive oocyte-like cells in vitro. Here, we show that a comparable population of small stem cells can be found in the ovarian tissue of women with borderline ovarian cancer, which, in contrast to small stem cells in “healthy” ovaries, formed spontaneous tumour-like structures and expressed some markers related to pluripotency and germinal lineage. The gene expression profile of these small putative cancer stem cells differed from similar cells sorted from “healthy” ovaries by 132 upregulated and 97 downregulated genes, including some important forkhead box and homeobox genes related to transcription regulation, developmental processes, embryogenesis, and ovarian cancer. These putative cancer stem cells are suggested to be a novel population of ovarian tumour-initiating cells in humans. PMID:27703207

Trait coordination, mechanical behaviour and growth form plasticity of Amborella trichopoda under variation in canopy openness

PubMed Central

Trueba, Santiago; Isnard, Sandrine; Barthélémy, Daniel; Olson, Mark E.

2016-01-01

Understanding the distribution of traits across the angiosperm phylogeny helps map the nested hierarchy of features that characterize key nodes. Finding that Amborella is sister to the rest of the angiosperms has raised the question of whether it shares certain key functional trait characteristics, and plastic responses apparently widespread within the angiosperms at large. With this in mind, we test the hypothesis that local canopy openness induces plastic responses. We used this variation in morphological and functional traits to estimate the pervasiveness of trait scaling and leaf and stem economics. We studied the architecture of Amborella and how it varies under different degrees of canopy openness. We analyzed the coordination of 12 leaf and stem structural and functional traits, and the association of this covariation with differing morphologies. The Amborella habit is made up of a series of sympodial modules that vary in size and branching pattern under different canopy openness. Amborella stems vary from self-supporting to semi-scandent. Changes in stem elongation and leaf size in Amborella produce distinct morphologies under different light environments. Correlations were found between most leaf and stem functional traits. Stem tissue rigidity decreased with increasing canopy openness. Despite substantial modulation of leaf size and leaf mass per area by light availability, branches in different light environments had similar leaf area-stem size scaling. The sympodial growth observed in Amborella could point to an angiosperm synapomorphy. Our study provides evidence of intraspecific coordination between leaf and stem economic spectra. Trait variation along these spectra is likely adaptive under different light environments and is consistent with these plastic responses having been present in the angiosperm common ancestor. PMID:27672131

Geographic and phenotypic variation in heartwood and essential-oil characters in natural populations of Santalum austrocaledonicum in Vanuatu.

PubMed

Page, Tony; Southwell, Ian; Russell, Mike; Tate, Hanington; Tungon, Joseph; Sam, Chanel; Dickinson, Geoff; Robson, Ken; Leakey, Roger R B

2010-08-01

Phenotypic variation in heartwood and essential-oil characters of Santalum austrocaledonicum was assessed across eleven populations on seven islands of Vanuatu. Trees differed significantly in their percentage heartwood cross-sectional area and this varied independently of stem diameter. The concentrations of the four major essential-oil constituents (alpha-santalol, beta-santalol, (Z)-beta-curcumen-12-ol, and cis-nuciferol) of alcohol-extracted heartwood exhibited at least tenfold and continuous tree-to-tree variation. Commercially important components alpha- and beta-santalol found in individual trees ranged from 0.8-47% and 0-24.1%, respectively, across all populations, and significant (P<0.05) differences for each were found between individual populations. The Erromango population was unique in that the mean concentrations of its monocyclic ((Z)-beta-curcumen-12-ol and cis-nuciferol) sesquiterpenes exceeded those of its bi- and tricyclic (alpha- and beta-santalol) sesquiterpenes. Heartwood colour varied between trees and spanned 65 colour categories, but no identifiable relationships were found between heartwood colour and alpha- and beta-santalol, although a weak relationship was evident between colour saturation and total oil concentration. These results indicate that the heartwood colour is not a reliable predictive trait for oil quality. The results of this study highlight the knowledge gaps in fundamental understanding of heartwood biology in Santalum genus. The intraspecific variation in heartwood cross-sectional area, oil concentration, and oil quality traits is of considerable importance to the domestication of sandalwood and present opportunities for the development of highly superior S. austrocaledonicum cultivars that conform to the industry's International Standards used for S. album.

7 CFR 51.1913 - Serious damage.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Soft ripe tomatoes or tomatoes affected by the soft rot. (b) Fresh holes or cuts, or any holes or cuts... adjacent to the stem scar and more than 1/4 inch in diameter. (h) Fruit actually infested with worms. ...

7 CFR 51.1913 - Serious damage.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Soft ripe tomatoes or tomatoes affected by the soft rot. (b) Fresh holes or cuts, or any holes or cuts... adjacent to the stem scar and more than 1/4 inch in diameter. (h) Fruit actually infested with worms. ...

Trunnionosis: Does Head Size Affect Fretting and Corrosion in Total Hip Arthroplasty?

PubMed

Del Balso, Christopher; Teeter, Matthew G; Tan, Sok Chuen; Howard, James L; Lanting, Brent A

2016-10-01

Wear and tribocorrosion at the modular head-neck taper interface may be a cause of failure in metal-on-polyethylene total hip arthroplasty (THA). The present investigation endeavored to elucidate the effect of femoral head diameter on fretting and corrosion in retrieved head-neck tapers. A retrieval analysis of THA prostheses in vivo for a minimum of 1 year was performed. Twenty-three femoral heads of 32-mm diameter were matched with 28-mm heads based on time in vivo and head length (-3 mm to +8 mm). All included implants featured a single taper design from a single manufacturer. Fretting and corrosion damage scoring was performed for each implant under stereomicroscopic visualization. Head diameter was observed to affect fretting (P = .01), with 32-mm femoral heads exhibiting greater total fretting scores than 28-mm heads. Fretting damage was greatest (P = .01) in the central concentric zone of the femoral head bore tapers, regardless of head diameter, length, or stem offset. No significant effect on total corrosion scores was observed for any head or stem variable. Retrieved implant total corrosion scores were positively correlated (ρ = 0.51, P < .001) with implantation time. Increased femoral head diameter in THA may produce greater fretting damage owing to and increased head-neck moment arm. There is no associated increase in corrosion with 28-mm and 32-mm heads of this taper design. The longer a THA prosthesis is implanted, the greater the risk of damage due to corrosion. Copyright © 2016 Elsevier Inc. All rights reserved.

[Effects of acid rain stress on Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth].

PubMed

Yin, Xiu-Min; Yu, Shu-Quan; Jiang, Hong; Liu, Mei-Hu

2010-06-01

A pot experiment was conducted to study the Eleocarpus glabripetalus seedlings leaf chlorophyll fluorescence characteristics and growth in different seasons under simulated acid rain stress (heavy, pH = 2. 5; moderate, pH = 4.0; and control, pH = 5.6). In the same treatments, the leaf relative chlorophyll content (SPAD), maximum PS II photochemical efficiency (F(v)/F(m)), actual PSII photochemical quantum yield (phi(PS II)), plant height, and stem diameter in different seasons were all in the order of October > July > April > January. In the same seasons, all the parameters were in the order of heavy acid rain > moderate acid rain > control. The interactions between different acid rain stress and seasons showed significant effects on the SPAD, F(v)/F(m), plant height, and stem diameter, but lesser effects on phi(PS II), qp and qN.

Detonation re-initiation in a concentric tube arrangement for C_2H_2/O_2/Ar mixtures

NASA Astrophysics Data System (ADS)

Wu, Y.; Lee, J. H. S.; Weng, C.

2017-05-01

Re-initiation of detonation in a concentric tube arrangement where a detonation exiting from a small diameter inner tube to a large diameter outer tube has been investigated. The outer tube diameter D is 50.8 mm and inner tube diameters d are 38, 25.4, and 12.7 mm giving diameter ratios D/d=1.34, 2, and 4. Stoichiometric C_2H_2-O_2 mixtures with argon dilution of 0, 25, 50, and 70% are used in the present study. Velocity measurements are made using photodiodes, and smoked foils downstream of the exit of the inner tube are also used to record the re-initiation process. Upon exit from the inner tube, the detonation suffers an abrupt decrease in velocity and at critical conditions, the velocity downstream of the exit is of the order of 50% of the Chapman-Jouguet velocity. It is found that re-initiation generally occurs within 10 tube diameters downstream of the exit. If re-initiation is not successful, the detonation continues to propagate at a low velocity for distances of the order of 30 tube diameters without any indication of flame acceleration of deflagration-to-detonation transition (DDT). Thus, the re-initiation process is clearly defined and distinct from the usual DDT in a smooth tube. The critical d/λ value ratio in the concentric tube is significantly lower than the usual unconfined case of d/λ =13 where λ is the detonation cell size. Thus, it is a result of re-initiation at the Mach stem of the reflected shock from the wall of the outer concentric tube. If re-initiation is not successful upon the first reflection, then subsequent multiple reflections at the tube axis and wall of the outer tube can also result in re-initiation. However, this is only observed for undiluted mixtures. For high-argon-diluted mixtures, re-initiation only occurs at the Mach stem of the first reflection.

Donor Dependent Variations in Hematopoietic Differentiation among Embryonic and Induced Pluripotent Stem Cell Lines

PubMed Central

Féraud, Olivier; Valogne, Yannick; Melkus, Michael W.; Zhang, Yanyan; Oudrhiri, Noufissa; Haddad, Rima; Daury, Aurélie; Rocher, Corinne; Larbi, Aniya; Duquesnoy, Philippe; Divers, Dominique; Gobbo, Emilie; Brunet de la Grange, Philippe; Louache, Fawzia; Bennaceur-Griscelli, Annelise; Mitjavila-Garcia, Maria Teresa

2016-01-01

Hematopoiesis generated from human embryonic stem cells (ES) and induced pluripotent stem cells (iPS) are unprecedented resources for cell therapy. We compared hematopoietic differentiation potentials from ES and iPS cell lines originated from various donors and derived them using integrative and non-integrative vectors. Significant differences in differentiation toward hematopoietic lineage were observed among ES and iPS. The ability of engraftment of iPS or ES-derived cells in NOG mice varied among the lines with low levels of chimerism. iPS generated from ES cell-derived mesenchymal stem cells (MSC) reproduce a similar hematopoietic outcome compared to their parental ES cell line. We were not able to identify any specific hematopoietic transcription factors that allow to distinguish between good versus poor hematopoiesis in undifferentiated ES or iPS cell lines. There is a relatively unpredictable variation in hematopoietic differentiation between ES and iPS cell lines that could not be predicted based on phenotype or gene expression of the undifferentiated cells. These results demonstrate the influence of genetic background in variation of hematopoietic potential rather than the reprogramming process. PMID:26938212

Label-free screening of niche-to-niche variation in satellite stem cells using functionalized pores

NASA Astrophysics Data System (ADS)

Chapman, Matthew R.; Balakrishnan, Karthik; Conboy, Michael J.; Mohanty, Swomitra; Jabart, Eric; Huang, Haiyan; Hack, James; Conboy, Irina M.; Sohn, Lydia L.

2012-02-01

Combinations of surface markers are currently used to identify muscle satellite cells. Using pores functionalized with specific antibodies and measuring the transit time of cells passing through these pores, we discovered remarkable heterogeneity in the expression of these markers in muscle (satellite) stem cells that reside in different single myofibers. Microniche-specific variation in stem cells of the same organ has not been previously described, as bulk analysis does not discriminate between separate myofibers or even separate hind-leg muscle groups. We found a significant population of Sca-1+ satellite cells that form myotubes, thereby demonstrating the myogenic potential of Sca-1+ cells, which are currently excluded in bulk sorting. Finally, using our label-free pore screening technique, we have been able to quantify directly surface expression of Notch1 without activation of the Notch pathway. We show for the first time Notch1-expression heterogeneity in unactivated satellite cells. The discovery of fiber-to-fiber variations prompts new research into the reasons for such diversity in muscle stem cells.

Effect of Pellet Size of Defoliation and Estimated Kill of Small Stems Treated with Hexazinone

Treesearch

J.L. Michael

1981-01-01

Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,2,5-triaine-2,4,(1H,2H)-dione] was tested in the 2, 1, and 0.5 cc size uellet (10% ai) against very small stems [average height, 1.97m; average ground line diameter (GLD), 2 cm] of water oak, Quercus nigra L., at 1.12 and 2.24 kg/ha on a sandy loam soil. First year defoliation of water oak by...

Scale dependence of disease impacts on quaking aspen (Populus tremuloides) mortality in the southwestern United States

USGS Publications Warehouse

Bell, David M.; Bradford, John B.; Lauenroth, William K.

2015-01-01

By examining variation in disease prevalence, mortality of healthy trees, and mortality of diseased trees, we showed that the role of disease in aspen tree mortality depended on the scale of inference. For variation among individuals in diameter, disease tended to expose intermediate-size trees experiencing moderate risk to greater risk. For spatial variation in summer temperature, disease exposed lower risk populations to greater mortality probabilities, but the magnitude of this exposure depended on summer precipitation. Furthermore, the importance of diameter and slenderness in mediating responses to climate supports the increasing emphasis on trait variation in studies of ecological responses to global change.

Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papi, M.; Paoletti, P.; Geraghty, B.

We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research.

The woody biomass resource of East Oklahoma, 1993

Treesearch

James F. Rosson

1993-01-01

Tables are presented for fresh and dry biomass estimates of major trees in east Oklahoma by forest type, ownership, species, stand basal area, tree class, diameter, and height. Information for total tree, stem, and crown components is included.

7 CFR 927.5 - Size.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Regulating Handling Definitions § 927.5 Size. Size means the number of pears which can be packed in a 44... diameter of the pear taken at right angles to a line running from the stem to the blossom end, or such...

7 CFR 927.5 - Size.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Regulating Handling Definitions § 927.5 Size. Size means the number of pears which can be packed in a 44... diameter of the pear taken at right angles to a line running from the stem to the blossom end, or such...

7 CFR 927.5 - Size.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Regulating Handling Definitions § 927.5 Size. Size means the number of pears which can be packed in a 44... diameter of the pear taken at right angles to a line running from the stem to the blossom end, or such...

7 CFR 927.5 - Size.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Regulating Handling Definitions § 927.5 Size. Size means the number of pears which can be packed in a 44... diameter of the pear taken at right angles to a line running from the stem to the blossom end, or such...

7 CFR 927.5 - Size.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Regulating Handling Definitions § 927.5 Size. Size means the number of pears which can be packed in a 44... diameter of the pear taken at right angles to a line running from the stem to the blossom end, or such...

Effects of shoot inversion on stem structure in Pharbitis nil

NASA Technical Reports Server (NTRS)

Prasad, T. K.; Sack, F. D.; Cline, M. G.

1988-01-01

The effects of shoot inversion on stem structure over 72 hr were investigated in Pharbitis nil by analyzing cell number, cell length, and the cross sectional areas of cells, tissues, and regions. An increase in stem diameter can be attributed to an increase in both cell number and cross sectional area of pith (primarily) and vascular tissue (secondarily). Qualitative observations of cell wall thickness in the light microscope did not reveal any significant effects of shoot inversion on this parameter. The inhibition of shoot elongation was accompanied by a significant decrease in cell length in the pith. The results are generally consistent with an ethylene effect on cell dimensions, especially in the pith.

Whole-tree transpiration and water-use partitioning between Eucalyptus nitens and Acacia dealbata weeds in a short-rotation plantation in northeastern Tasmania.

PubMed

Hunt, Mark A.; Beadle, Christopher L.

1998-01-01

Whole-tree water use in 4- and 8-year-old plantations of Eucalyptus nitens Deane and Maiden (ex Maiden) in the presence and absence of Acacia dealbata Link. weeds was estimated by the heat pulse velocity technique during a six-week summer period. Maximum sap velocities were recorded between 5 and 15 mm under the cambium for both eucalypt and acacia trees, and marked radial and axial variations in sap velocity were observed. The latter source of variation was most pronounced in mixed stands where crowns were asymmetrical. Mean daily sap flux ranged from 1.4 to 103.6 l day(-1) for eucalypts and from < 0.1 to 8.4 l day(-1) for acacias. Stem diameter explained 98% of the variation in sapwood area for E. nitens and 89% for A. dealbata, and was determined to be a suitable parameter for scaling water use from the tree to stand level. Plot transpiration varied from 1.4 to 2.8 mm day(-1) in mixed 8-year-old plots and was 0.85 mm day(-1) in a mixed 4-year-old plot. The degree of A. dealbata infestation was associated with absolute plot water use and regression models predicted that, in the absence of acacia competition, plot water use for the 8-year-old stand would approach 5-6 mm day(-1) during the growing season.

Widening of xylem conduits in a conifer tree depends on the longer time of cell expansion downwards along the stem

PubMed Central

Anfodillo, Tommaso; Deslauriers, Annie; Menardi, Roberto; Tedoldi, Laura; Petit, Giai; Rossi, Sergio

2012-01-01

The diameter of vascular conduits increases towards the stem base. It has been suggested that this profile is an efficient anatomical feature for reducing the hydraulic resistance when trees grow taller. However, the mechanism that controls the cell diameter along the plant is not fully understood. The timing of cell differentiation along the stem was investigated. Cambial activity and cell differentiation were investigated in a Picea abies tree (11.5 m in height) collecting microsamples at nine different heights (from 1 to 9 m) along the stem with a 4 d time interval. Wood sections (8–12 μm thick) were stained and observed under a light microscope with polarized light to differentiate the developing xylem cells. Cell wall lignification was detected using cresyl violet acetate. The first enlarging cells appeared almost simultaneously along the tree axis indicating that cambium activation is not height-dependent. A significant increase in the duration of the cell expansion phase was observed towards the tree base: at 9 m from the ground, xylem cells expanded for 7 d, at 6 m for 14 d, and at 3 m for 19 d. The duration of the expansion phase is positively correlated with the lumen area of the tracheids (r2=0.68, P < 0.01) at the same height. By contrast, thickness of the cell wall of the earlywood did not show any trend with height. The lumen area of the conduits down the stem appeared linearly dependent on time during which differentiating cells remained in the expansion phase. However, the inductive signal of such long-distance patterned differentiation remains to be identified. PMID:22016427

Widening of xylem conduits in a conifer tree depends on the longer time of cell expansion downwards along the stem.

PubMed

Anfodillo, Tommaso; Deslauriers, Annie; Menardi, Roberto; Tedoldi, Laura; Petit, Giai; Rossi, Sergio

2012-01-01

The diameter of vascular conduits increases towards the stem base. It has been suggested that this profile is an efficient anatomical feature for reducing the hydraulic resistance when trees grow taller. However, the mechanism that controls the cell diameter along the plant is not fully understood. The timing of cell differentiation along the stem was investigated. Cambial activity and cell differentiation were investigated in a Picea abies tree (11.5 m in height) collecting microsamples at nine different heights (from 1 to 9 m) along the stem with a 4 d time interval. Wood sections (8-12 μm thick) were stained and observed under a light microscope with polarized light to differentiate the developing xylem cells. Cell wall lignification was detected using cresyl violet acetate. The first enlarging cells appeared almost simultaneously along the tree axis indicating that cambium activation is not height-dependent. A significant increase in the duration of the cell expansion phase was observed towards the tree base: at 9 m from the ground, xylem cells expanded for 7 d, at 6 m for 14 d, and at 3 m for 19 d. The duration of the expansion phase is positively correlated with the lumen area of the tracheids (r(2)=0.68, P < 0.01) at the same height. By contrast, thickness of the cell wall of the earlywood did not show any trend with height. The lumen area of the conduits down the stem appeared linearly dependent on time during which differentiating cells remained in the expansion phase. However, the inductive signal of such long-distance patterned differentiation remains to be identified.

Interplanting woody nurse crops promotes differential growth of black walnut saplings

Treesearch

J. O. Dawson; J. W. Van Sambeek

1993-01-01

Interplanting black walnut (Juglans nigra) with four different nitrogen fixing, woody nurse crops (Alnus glutinosa, Elaeagnus umbellata, E. angustifolia or Caragana arborescens) increased annual walnut height and stem diameter (dbh) growth overall by as much as 50% and...

A transmission electron microscopy study of CoFe2O4 ferrite nanoparticles in silica aerogel matrix using HREM and STEM imaging and EDX spectroscopy and EELS.

PubMed

Falqui, Andrea; Corrias, Anna; Wang, Peng; Snoeck, Etienne; Mountjoy, Gavin

2010-04-01

Magnetic nanocomposite materials consisting of 5 and 10 wt% CoFe2O4 nanoparticles in a silica aerogel matrix have been synthesized by the sol-gel method. For the CoFe2O4-10wt% sample, bright-field scanning transmission electron microscopy (BF STEM) and high-resolution transmission electron microscopy (HREM) images showed distinct, rounded CoFe2O4 nanoparticles, with typical diameters of roughly 8 nm. For the CoFe2O4-5wt% sample, BF STEM images and energy dispersive X-ray (EDX) measurements showed CoFe2O4 nanoparticles with diameters of roughly 3 +/- 1 nm. EDX measurements indicate that all nanoparticles consist of stoichiometric CoFe2O4, and electron energy-loss spectroscopy measurements from lines crossing nanoparticles in the CoFe2O4-10wt% sample show a uniform composition within nanoparticles, with a precision of at best than +/-0.5 nm in analysis position. BF STEM images obtained for the CoFe2O4-10wt% sample showed many "needle-like" nanostructures that typically have a length of 10 nm and a width of 1 nm, and frequently appear to be attached to nanoparticles. These needle-like nanostructures are observed to contain layers with interlayer spacing 0.33 +/- 0.1 nm, which could be consistent with Co silicate hydroxide, a known precursor phase in these nanocomposite materials.

Elucidation of the genetic basis of variation for stem strength characteristics in bread wheat by Associative Transcriptomics.

PubMed

Miller, Charlotte N; Harper, Andrea L; Trick, Martin; Werner, Peter; Waldron, Keith; Bancroft, Ian

2016-07-16

The current approach to reducing the tendency for wheat grown under high fertilizer conditions to collapse (lodge) under the weight of its grain is based on reducing stem height via the introduction of Rht genes. However, these reduce the yield of straw (itself an important commodity) and introduce other undesirable characteristics. Identification of alternative height-control loci is therefore of key interest. In addition, the improvement of stem mechanical strength provides a further way through which lodging can be reduced. To investigate the prospects for genetic alternatives to Rht, we assessed variation for plant height and stem strength properties in a training genetic diversity panel of 100 wheat accessions fixed for Rht. Using mRNAseq data derived from RNA purified from leaves, functional genotypes were developed for the panel comprising 42,066 Single Nucleotide Polymorphism (SNP) markers and 94,060 Gene Expression Markers (GEMs). In the first application in wheat of the recently-developed method of Associative Transcriptomics, we identified associations between trait variation and both SNPs and GEMs. Analysis of marker-trait associations revealed candidates for the causative genes underlying the trait variation, implicating xylan acetylation and the COP9 signalosome as contributing to stem strength and auxin in the control of the observed variation for plant height. Predictive capabilities of key markers for stem strength were validated using a test genetic diversity panel of 30 further wheat accessions. This work illustrates the power of Associative Transcriptomics for the exploration of complex traits of high agronomic importance in wheat. The careful selection of genotypes included in the analysis, allowed for high resolution mapping of novel trait-controlling loci in this staple crop. The use of Gene Expression markers coupled with the more traditional sequence-based markers, provides the power required to understand the biological context of the marker-trait associations observed. This not only adds to the wealth of knowledge that we strive to accumulate regarding gene function and plant adaptation, but also provides breeders with the information required to make more informed decisions regarding the potential consequences of incorporating the use of particular markers into future breeding programmes.

Twenty-four years after theYellowstone Fires: Are postfire lodgepole pine stands converging in structure and function?

PubMed

Turner, Monica G; Whitby, Timothy G; Tinker, Daniel B; Romme, William H

2016-05-01

Disturbance and succession have long been of interest in ecology, but how landscape patterns of ecosystem structure and function evolve following large disturbances is poorly understood. After nearly 25 years, lodgepole pine (Pinus contorta var. latifolia) forests that regenerated after the 1988 Yellowstone Fires (Wyoming, USA) offer a prime opportunity to track the fate of disturbance-created heterogeneity in stand structure and function in a wilderness setting. In 2012, we resampled 72 permanent plots to ask (1) How have postfire stand structure and function changed between 11 and 24 yr postfire, and what variables explain these patterns and changes? (2) How has landscape-level (among-stand) variability in postfire stand structure and function changed between 11 and 24 yr postfire? We expected to see evidence of convergence beginning to emerge, but also that initial postfire stem density would still determine trajectories of biomass accumulation. After 24 yr, postfire lodgepole pine density remained very high (mean = 21,738 stems/ha, range = 0-344,067 stems/ha). Stem density increased in most plots between 11 and 24 yr postfire, but declined sharply where 11-yr-postfire stem density was > 72,000 stems/ha. Stems were small in high-density stands, but stand-level lodgepole pine leaf area, foliage biomass, and live aboveground biomass increased over time and with increasing stem density. After 24 yr, mean annual lodgepole pine aboveground net primary production (ANPP) was high (mean = 5 Mg · ha⁻¹ · yr⁻¹, range = 0-16.5 Mg · ha⁻¹ · yr⁻¹). Among stands, lodgepole pine ANPP increased with stem density, which explained 69% of the variation; another 8% of the variation was explained by environmental covariates. Early patterns of postfire lodgepole pine regeneration, which were contingent on prefire serotiny and fire severity, remained the dominant driver of stand structure and function. We observed mechanisms that would lead to convergence in stem density (structure) over time, but it was landscape variation in functional variables that declined substantially. Stand structure and function have not converged across the burned landscape, but our evidence suggests function will converge sooner than structure.

Exploring the regulatory role of isocitrate dehydrogenase mutant protein on glioma stem cell proliferation.

PubMed

Lu, H-C; Ma, J; Zhuang, Z; Qiu, F; Cheng, H-L; Shi, J-X

2016-08-01

Glioma is the most lethal form of cancer that originates mostly from the brain and less frequently from the spine. Glioma is characterized by abnormal regulation of glial cell differentiation. The severity of the glioma was found to be relaxed in isocitrate dehydrogenase 1 (IDH1) mutant. The present study focused on histological discrimination and regulation of cancer stem cell between IDH1 mutant and in non-IDH1 mutant glioma tissue. Histology, immunohistochemistry and Western blotting techniques are used to analyze the glioma nature and variation in glioma stem cells that differ between IDH1 mutant and in non-IDH1 mutant glioma tissue. The aggressive form of non-IDH1 mutant glioma shows abnormal cellular histological variation with prominent larger nucleus along with abnormal clustering of cells. The longer survival form of IDH1 mutant glioma has a control over glioma stem cell proliferation. Immunohistochemistry with stem cell markers, CD133 and EGFRvIII are used to demonstrate that the IDH1 mutant glioma shows limited dependence on cancer stem cells and it shows marked apoptotic signals in TUNEL assay to regulate abnormal cells. The non-IDH1 mutant glioma failed to regulate misbehaving cells and it promotes cancer stem cell proliferation. Our finding supports that the IDH1 mutant glioma has a regulatory role in glioma stem cells and their survival.

Fast and Robust STEM Reconstruction in Complex Environments Using Terrestrial Laser Scanning

NASA Astrophysics Data System (ADS)

Wang, D.; Hollaus, M.; Puttonen, E.; Pfeifer, N.

2016-06-01

Terrestrial Laser Scanning (TLS) is an effective tool in forest research and management. However, accurate estimation of tree parameters still remains challenging in complex forests. In this paper, we present a novel algorithm for stem modeling in complex environments. This method does not require accurate delineation of stem points from the original point cloud. The stem reconstruction features a self-adaptive cylinder growing scheme. This algorithm is tested for a landslide region in the federal state of Vorarlberg, Austria. The algorithm results are compared with field reference data, which show that our algorithm is able to accurately retrieve the diameter at breast height (DBH) with a root mean square error (RMSE) of ~1.9 cm. This algorithm is further facilitated by applying an advanced sampling technique. Different sampling rates are applied and tested. It is found that a sampling rate of 7.5% is already able to retain the stem fitting quality and simultaneously reduce the computation time significantly by ~88%.

Coordination between leaf and stem traits related to leaf carbon gain and hydraulics across 32 drought-tolerant angiosperms.

PubMed

Ishida, Atsushi; Nakano, Takashi; Yazaki, Kenichi; Matsuki, Sawako; Koike, Nobuya; Lauenstein, Diego L; Shimizu, Michiru; Yamashita, Naoko

2008-05-01

We examined 15 traits in leaves and stems related to leaf C economy and water use for 32 co-existing angiosperms at ridge sites with shallow soil in the Bonin Islands. Across species, stem density was positively correlated to leaf mass per area (LMA), leaf lifespan (LLS), and total phenolics and condensed tannins per unit leaf N (N-based), and negatively correlated to leaf osmotic potential and saturated water content in leaves. LMA and LLS were negatively correlated to photosynthetic parameters, such as area-, mass-, and N-based assimilation rates. Although stem density and leaf osmotic potential were not associated with photosynthetic parameters, they were associated with some parameters of the leaf C economy, such as LMA and LLS. In the principal component (PCA) analysis, the first three axes accounted for 74.4% of total variation. Axis 1, which explained 41.8% of the total variation, was well associated with parameters for leaf C and N economy. Similarly, axis 2, which explained 22.3% of the total variation, was associated with parameters for water use. Axis 3, which explained 10.3% of the total variation, was associated with chemical defense within leaves. Axes 1 and 2 separated functional types relatively well, i.e., creeping trees, ruderal trees, other woody plants, C(3) shrubs and forbs, palms, and CAM plants, indicating that plant functional types were characterized by similar attributes of traits related to leaf C and N economy and water use. In addition, when the plot was extended by two unrelated traits, leaf mass-based assimilation rates and stem density, it also separated these functional types. These data indicate that differences in the functional types with contrasting plant strategies can be attributed to functional integration among leaf C economy, hydraulics, and leaf longevity, and that both leaf mass-based assimilation rates and stem density are key factors reflecting the different functions of plant species.

Gravitropism in Higher Plant Shoots 1

PubMed Central

Mueller, Wesley J.; Salisbury, Frank B.; Blotter, P. Thomas

1984-01-01

Dimensional changes during gravitropic bending of cocklebur (Xanthium strumarium L.) dicot stems were measured using techniques of stereo photogrammetry. The differential growth is from an increased growth rate on the bottom of the stem and a stopping or contraction of the top. Contraction of the top was especially evident upon release and immediate bending of horizontal stems that had been restrained between stiff wires for 36 hours. The energy for this could have been stored in both the top and bottom, since the bottom elongated, and the top contracted. Forces developed during bending were measured by fastening a stem tip to the end of a bar with attached strain gauges and recording electrical output from the strain gauges. Restrained mature cocklebur stems continued to accumulate potential energy for bending for about 120 hours, after which the recorded force reached a maximum. Pressures within castor bean (Ricinus communis L.) stems were also measured with 3.5-millimeter diameter pressure transducers. As expected, the pressure on the bottom of the restrained plants increased with time; pressures decreased in vertical controls, tops of restrained stems, and bottoms of free-bending stems. Pressures increased in tops of free-bending stems. When restrained plants were released, pressure on the bottom decreased and pressure on the top increased. Results suggest a possible role for cell contraction in the top of stems bending upward in response to gravity. Images Fig. 5 Fig. 11 PMID:16663987

Black-backed woodpecker habitat suitability mapping using conifer snag basal area estimated from airborne laser scanning

NASA Astrophysics Data System (ADS)

Casas Planes, Á.; Garcia, M.; Siegel, R.; Koltunov, A.; Ramirez, C.; Ustin, S.

2015-12-01

Occupancy and habitat suitability models for snag-dependent wildlife species are commonly defined as a function of snag basal area. Although critical for predicting or assessing habitat suitability, spatially distributed estimates of snag basal area are not generally available across landscapes at spatial scales relevant for conservation planning. This study evaluates the use of airborne laser scanning (ALS) to 1) identify individual conifer snags and map their basal area across a recently burned forest, and 2) map habitat suitability for a wildlife species known to be dependent on snag basal area, specifically the black-backed woodpecker (Picoides arcticus). This study focuses on the Rim Fire, a megafire that took place in 2013 in the Sierra Nevada Mountains of California, creating large patches of medium- and high-severity burned forest. We use forest inventory plots, single-tree ALS-derived metrics and Gaussian processes classification and regression to identify conifer snags and estimate their stem diameter and basal area. Then, we use the results to map habitat suitability for the black-backed woodpecker using thresholds for conifer basal area from a previously published habitat suitability model. Local maxima detection and watershed segmentation algorithms resulted in 75% detection of trees with stem diameter larger than 30 cm. Snags are identified with an overall accuracy of 91.8 % and conifer snags are identified with an overall accuracy of 84.8 %. Finally, Gaussian process regression reliably estimated stem diameter (R2 = 0.8) using height and crown area. This work provides a fast and efficient methodology to characterize the extent of a burned forest at the tree level and a critical tool for early wildlife assessment in post-fire forest management and biodiversity conservation.

In vitro evaluation of the human gingival fibroblast/gingival mesenchymal stem cell dynamics through perforated guided tissue membranes: cell migration, proliferation and membrane stiffness assay.

PubMed

Gamal, A Y; Al-Berry, N N; Hassan, A A; Rashed, L A; Iacono, V J

2017-06-01

Migration of gingival fibroblasts/gingival mesenchymal stem cells through macro-perforated barrier membranes may allow them to participate positively in periodontal regeneration. The optimal guided tissue membrane perforation diameter that could favor maximum cell migration into the defect area and at the same time act as an occlusive barrier for gingival epithelium and its associated gingival extracellular matrix component is not yet identified. Cultured human gingival fibroblasts/gingival mesenchymal stem cells were placed in the upper chambers of 12-well collagen-coated polytetrafluoroethylene transwells, which were manually perforated with 0.2, 0.4 and 0.7 mm sized pores. The lower chambers of the transwells received blood clot as an attraction medium. The number of cells that have migrated to the lower chambers was calculated. Proliferation of these cells was evaluated using MTT assay. Scanning electron microscopy images were obtained for the lower surfaces of the transwell membranes. Perforated bovine collagen membranes (Tutopatch ® ) were subjected to mechanical testing to determine the tensile strength and modulus of elasticity. Group 3 (0.7 mm) showed significantly higher values for cell migration and proliferation. All groups showed a small degree of extracellular matrix migration through membrane perforations. Scanning electron microscopy evaluation revealed variable numbers of cells in fibrin matrices located mainly around the pore edges. There were non-significant differences between groups regarding mechanical properties. The present study demonstrated that macro-membrane perforations of 0.2, 0.4 and 0.7 mm are suitable pore diameters that could maintain membrane stiffness and allow for cellular migration. However, these membrane perforation diameters did not allow for total gingival connective tissue isolation. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Norway maple displays greater seasonal growth and phenotypic plasticity to light than native sugar maple.

PubMed

Paquette, Alain; Fontaine, Bastien; Berninger, Frank; Dubois, Karine; Lechowicz, Martin J; Messier, Christian; Posada, Juan M; Valladares, Fernando; Brisson, Jacques

2012-11-01

Norway maple (Acer platanoides L), which is among the most invasive tree species in forests of eastern North America, is associated with reduced regeneration of the related native species, sugar maple (Acer saccharum Marsh) and other native flora. To identify traits conferring an advantage to Norway maple, we grew both species through an entire growing season under simulated light regimes mimicking a closed forest understorey vs. a canopy disturbance (gap). Dynamic shade-houses providing a succession of high-intensity direct-light events between longer periods of low, diffuse light were used to simulate the light regimes. We assessed seedling height growth three times in the season, as well as stem diameter, maximum photosynthetic capacity, biomass allocation above- and below-ground, seasonal phenology and phenotypic plasticity. Given the north European provenance of Norway maple, we also investigated the possibility that its growth in North America might be increased by delayed fall senescence. We found that Norway maple had significantly greater photosynthetic capacity in both light regimes and grew larger in stem diameter than sugar maple. The differences in below- and above-ground biomass, stem diameter, height and maximum photosynthesis were especially important in the simulated gap where Norway maple continued extension growth during the late fall. In the gap regime sugar maple had a significantly higher root : shoot ratio that could confer an advantage in the deepest shade of closed understorey and under water stress or browsing pressure. Norway maple is especially invasive following canopy disturbance where the opposite (low root : shoot ratio) could confer a competitive advantage. Considering the effects of global change in extending the potential growing season, we anticipate that the invasiveness of Norway maple will increase in the future.

Coefficients of discharge of fuel-injection nozzles for compression-ignition engines

NASA Technical Reports Server (NTRS)

Gelalles, A G

1932-01-01

This report presents the results of an investigation to determine the coefficients of discharge of nozzles with small, round orifices of the size used with high-speed compression-ignition engines. The injection pressures and chamber back pressures employed were comparable to those existing in compression-ignition engines during injection. The construction of the nozzles was varied to determine the effect of the nozzle design on the coefficient. Tests were also made with nozzles assembled in an automatic injection valve, both with a plain and with a helically grooved stem. It was found that a smooth passage before the orifice is requisite for high flow efficiency. A beveled leading edge before the orifice gave a higher coefficient of discharge than a rounded edge. The results with the nozzles assembled in an automatic injection valve having a plain stem duplicated those with the nozzles assembled at the end of a straight tube of constant diameter. Lower coefficients were obtained with the nozzles assembled in an injection valve having a helically grooved stem. When the coefficients of nozzles of any one geometrical shape were plotted against values of corresponding Reynold's numbers for the orifice diameters and rates of flow tested, it was found that experimental points were distributed along a single curve.

Management of Atriplex nummularia Lindl. in a salt affected soil in a semi arid region of Brazil.

PubMed

de Souza, Edivan Rodrigues; Freire, Maria Betânia Galvão dos Santos; de Melo, Diego Vandeval Maranhão; Montenegro, Abelardo de Antônio Assunção

2014-01-01

This study aims to investigate the behavior of Atriplex nummularia under field conditions, including its growth, periodic cuttings, salt extraction, and soil chemical properties monitored for 16 months. Three treatments were evaluated: soil cultivated with Atriplex pruned at 6 and 12 months after transplanting (MAT); soil cultivated with plants that were harvested only at the end of the experiment (16 MAT); and a control (uncultivated soil) with four replications. Soil samplings were taken at 0, 6, 12, and 16 MAT. The samples were taken at depths of 0-20, 20-40, 40-60, and 60-80 cm. Biometric variables for growth were monitored monthly. The shoot was divided into leaves, thin stems (< or = 3 mm diameter), and thick stems (> 3 mm diameter) to determine its content of Ca, Mg, Na, K, and Cl. We concluded that pruning regime for Atriplex was efficient mainly because it stimulated regrowth of less lignified material (leaves and stems < or = 3 mm). We found that elements extracted by plant tissue can be quantified accurately, making them valuable indicators of the efficiency of the recovery process. The use of the Atriplex is recommended because the the possibility of revegetating areas inhospitable to most species used in conventional farming.

An Application of System Dynamics Analysis to Ecosystem Management at the Poinsett Weapons Range, Shaw AFB SC

DTIC Science & Technology

1997-12-01

younger trees with thinner sapwood and greater heartwood diameter than other trees in the area . The RCW requires approximately 6 inches in diameter...and management areas and have explored applications of system dynamics modeling at the graduate level. The attached application addresses specific...Population Sensitivity to Birth Rate 62 10. RCW Population with Variation of Relatedness Entity 64 11. RCW Population with Variation of Foraging Area

Fire induced reproductive mechanisms of a Symphoricarpos (Caprifoliaceae) shrub after dormant season burning.

PubMed

Scasta, John Derek; Engle, David M; Harr, Ryan N; Debinski, Diane M

2014-12-01

Symphoricarpos, a genus of the Caprifoliaceae family, consists of about 15 species of clonal deciduous shrubs in North America and 1 species endemic to China. In North American tallgrass prairie, Symphoricarpos orbiculatus (buckbrush) is the dominant shrub often forming large colonies via sexual and asexual reproductive mechanisms. Symphoricarpos shrubs, in particular S. orbiculatus, use a unique sexual reproductive mechanism known as layering where vertical stems droop and the tips root upon contact with the soil. Because of conflicting societal values of S. orbiculatus for conservation and agriculture and the current attempt to restore historical fire regimes, there is a need for basic research on the biological response of S. orbiculatus to anthropogenic burning regimes. From 2007 through 2013 we applied prescribed fires in the late dormant season on grazed pastures in the Grand River Grasslands of Iowa. From 2011 to 2013, we measured how S. orbiculatus basal resprouting and layering stems were affected by patchy fires on grazed pastures, complete pasture fires on grazed pastures or fire exclusion without grazing for more than three years. We measured ramet height, ramet canopy diameter, stems per ramet, ramets per 100 m 2 , and probability of new layering stems 120 days after fire. Height in burned plots was lower than unburned plots but S. orbiculatus reached ~ 84% of pre-burn height 120 days after fire. Stems per ramet were 2x greater in the most recently burned plots due to basal re-sprouting. Canopy diameter and density of ramets was not affected by time since fire, but burned pastures had marginally lower densities than plots excluded from fire (P = 0.07). Fire triggered new layering stems and no new layering stems were found in plots excluded from fire. The mechanisms of both basal sprouting and aerial layering after fire suggest S. orbiculatus is tolerant to dormant season fires. Furthermore, dormant season fires, regardless if they were patchy fires or complete pasture fires, did not result in mortality of S. orbiculatus. Dormant season fires can reduce S. orbiculatus structural dominance and maintain lower ramet densities but also trigger basal resprouting and layering.

Regulation of water flux through tropical forest canopy trees: do universal rules apply?

PubMed

Meinzer, F C; Goldstein, G; Andrade, J L

2001-01-01

Tropical moist forests are notable for their richness in tree species. The presence of such a diverse tree flora presents potential problems for scaling up estimates of water use from individual trees to entire stands and for drawing generalizations about physiological regulation of water use in tropical trees. We measured sapwood area or sap flow, or both, in 27 co-occurring canopy species in a Panamanian forest to determine the extent to which relationships between tree size, sapwood area and sap flow were species-specific, or whether they were constrained by universal functional relationships between tree size, conducting xylem area, and water use. For the 24 species in which active xylem area was estimated over a range of size classes, diameter at breast height (DBH) accounted for 98% of the variation in sapwood area and 67% of the variation in sapwood depth when data for all species were combined. The DBH alone also accounted for > or = 90% of the variation in both maximum and total daily sap flux density in the outermost 2 cm of sapwood for all species taken together. Maximum sap flux density measured near the base of the tree occurred at about 1,400 h in the largest trees and 1,130 h in the smallest trees studied, and DBH accounted for 93% of the variation in the time of day at which maximum sap flow occurred. The shared relationship between tree size and time of maximum sap flow at the base of the tree suggests that a common relationship between diurnal stem water storage capacity and tree size existed. These results are consistent with a recent hypothesis that allometric scaling of plant vascular systems, and therefore water use, is universal.

15N in tree rings as a bio-indicator of changing nitrogen cycling in tropical forests: an evaluation at three sites using two sampling methods

PubMed Central

van der Sleen, Peter; Vlam, Mart; Groenendijk, Peter; Anten, Niels P. R.; Bongers, Frans; Bunyavejchewin, Sarayudh; Hietz, Peter; Pons, Thijs L.; Zuidema, Pieter A.

2015-01-01

Anthropogenic nitrogen deposition is currently causing a more than twofold increase of reactive nitrogen input over large areas in the tropics. Elevated 15N abundance (δ15N) in the growth rings of some tropical trees has been hypothesized to reflect an increased leaching of 15N-depleted nitrate from the soil, following anthropogenic nitrogen deposition over the last decades. To find further evidence for altered nitrogen cycling in tropical forests, we measured long-term δ15N values in trees from Bolivia, Cameroon, and Thailand. We used two different sampling methods. In the first, wood samples were taken in a conventional way: from the pith to the bark across the stem of 28 large trees (the “radial” method). In the second, δ15N values were compared across a fixed diameter (the “fixed-diameter” method). We sampled 400 trees that differed widely in size, but measured δ15N in the stem around the same diameter (20 cm dbh) in all trees. As a result, the growth rings formed around this diameter differed in age and allowed a comparison of δ15N values over time with an explicit control for potential size-effects on δ15N values. We found a significant increase of tree-ring δ15N across the stem radius of large trees from Bolivia and Cameroon, but no change in tree-ring δ15N values over time was found in any of the study sites when controlling for tree size. This suggests that radial trends of δ15N values within trees reflect tree ontogeny (size development). However, for the trees from Cameroon and Thailand, a low statistical power in the fixed-diameter method prevents to conclude this with high certainty. For the trees from Bolivia, statistical power in the fixed-diameter method was high, showing that the temporal trend in tree-ring δ15N values in the radial method is primarily caused by tree ontogeny and unlikely by a change in nitrogen cycling. We therefore stress to account for tree size before tree-ring δ15N values can be properly interpreted. PMID:25914707

Stem cell-extracellular vesicles as drug delivery systems: New frontiers for silk/curcumin nanoparticles.

PubMed

Perteghella, Sara; Crivelli, Barbara; Catenacci, Laura; Sorrenti, Milena; Bruni, Giovanna; Necchi, Vittorio; Vigani, Barbara; Sorlini, Marzio; Torre, Maria Luisa; Chlapanidas, Theodora

2017-03-30

The aim of this work was to develop a novel carrier-in-carrier system based on stem cell-extracellular vesicles loaded of silk/curcumin nanoparticles by endogenous technique. Silk nanoparticles were produced by desolvation method and curcumin has been selected as drug model because of its limited water solubility and poor bioavailability. Nanoparticles were stable, with spherical geometry, 100nm in average diameter and the drug content reached about 30%. Cellular uptake studies, performed on mesenchymal stem cells (MSCs), showed the accumulation of nanoparticles in the cytosol around the nuclear membrane, without cytotoxic effects. Finally, MSCs were able to release extracellular vesicles entrapping silk/curcumin nanoparticles. This combined biological-technological approach represents a novel class of nanosystems, combining beneficial effects of both regenerative cell therapies and pharmaceutical nanomedicine, avoiding the use of viable replicating stem cells. Copyright © 2017 Elsevier B.V. All rights reserved.

Additive Manufacturing of Patient-Customizable Scaffolds for Tubular Tissues Using the Melt-Drawing Method.

PubMed

Tan, Yu Jun; Tan, Xipeng; Yeong, Wai Yee; Tor, Shu Beng

2016-11-03

Polymeric fibrous scaffolds for guiding cell growth are designed to be potentially used for the tissue engineering (TE) of tubular organs including esophagi, blood vessels, tracheas, etc. Tubular scaffolds were fabricated via melt-drawing of highly elastic poly(l-lactide-co-ε-caprolactone) (PLC) fibers layer-by-layer on a cylindrical mandrel. The diameter and length of the scaffolds are customizable via 3D printing of the mandrel. Thickness of the scaffolds was varied by changing the number of layers of the melt-drawing process. The morphology and tensile properties of the PLC fibers were investigated. The fibers were highly aligned with a uniform diameter. Their diameters and tensile properties were tunable by varying the melt-drawing speeds. These tailorable topographies and tensile properties show that the additive-based scaffold fabrication technique is customizable at the micro- and macro-scale for different tubular tissues. The merits of these scaffolds in TE were further shown by the finding that myoblast and fibroblast cells seeded onto the scaffolds in vitro showed appropriate cell proliferation and distribution. Human mesenchymal stem cells (hMSCs) differentiated to smooth muscle lineage on the microfibrous scaffolds in the absence of soluble induction factors, showing cellular shape modulation and scaffold elasticity may encourage the myogenic differentiation of stem cells.

Effects of climate variables on intra-annual stem radial increment in Pinus cembra (L.) along the alpine treeline ecotone

PubMed Central

GRUBER, Andreas; ZIMMERMANN, Jolanda; WIESER, Gerhard; OBERHUBER, Walter

2011-01-01

Within the alpine treeline ecotone tree growth is increasingly restricted by extreme climate conditions. Although intra-annual stem growth recorded by dendrometers can be linked to climate, stem diameter increments in slow-growing subalpine trees are masked by changes in tree water status. We tested the hypothesis that intra-annual radial stem growth in Pinus cembra is influenced by different climate variables along the treeline ecotone in the Austrian Alps. Dendrometer traces were compared with dynamics of xylem cell development to date onset of cambial activity and radial stem growth in spring. Daily fluctuations in stem radius reflected changes in tree water status throughout the treeline ecotone. Extracted daily radial increments were significantly correlated with air temperature at the timberline and treeline only, where budburst, cambial activity and enlargement of first tracheids also occurred quite similarly. A close relationship was detected between radial increment and number of enlarging tracheids throughout the treeline ecotone. We conclude that (i) the relationship between climate and radial stem growth within the treeline ecotone is dependent on a close coupling to atmospheric climate conditions and (ii) initiation of cambial activity and radial growth in spring can be distinguished from stem re-hydration by histological analysis. PMID:21423861

Effects of climate variables on intra-annual stem radial increment in Pinus cembra (L.) along the alpine treeline ecotone.

PubMed

Gruber, Andreas; Zimmermann, Jolanda; Wieser, Gerhard; Oberhuber, Walter

2009-08-01

Within the alpine treeline ecotone tree growth is increasingly restricted by extreme climate conditions. Although intra-annual stem growth recorded by dendrometers can be linked to climate, stem diameter increments in slow-growing subalpine trees are masked by changes in tree water status.We tested the hypothesis that intra-annual radial stem growth in Pinus cembra is influenced by different climate variables along the treeline ecotone in the Austrian Alps. Dendrometer traces were compared with dynamics of xylem cell development to date onset of cambial activity and radial stem growth in spring.Daily fluctuations in stem radius reflected changes in tree water status throughout the treeline ecotone. Extracted daily radial increments were significantly correlated with air temperature at the timberline and treeline only, where budburst, cambial activity and enlargement of first tracheids also occurred quite similarly. A close relationship was detected between radial increment and number of enlarging tracheids throughout the treeline ecotone.We conclude that (i) the relationship between climate and radial stem growth within the treeline ecotone is dependent on a close coupling to atmospheric climate conditions and (ii) initiation of cambial activity and radial growth in spring can be distinguished from stem re-hydration by histological analysis.

Fine structures of embryonic discs of in vivo post-hatching porcine blastocysts at the pre-primitive streak stage.

PubMed

Xia, P; Liu, Z; Qin, P

2011-04-01

To date, reports about the ultrastructure of porcine embryonic discs have not shown details of the primitive streak. The main objective of this study was to examine the ultrastructure of interior and exterior embryonic discs in porcine in vivo blastocysts with diameters of 1, 3 and 9 mm using scanning electron microscopy and transmission electron microscopy. For the first time, we revealed the ultrastructure of the unusual group of cells in the pre-primitive streak area of embryonic discs. The cells were 1-2 μm in diameter, had high electron density and contained abundant, free ribosomes and endoplasmic reticulum. These primitive streak cells could represent original embryonic stem cells or represent a stem cell niche. The results also showed three types of cells on the exterior surface of the embryonic discs. Moreover, our results provided morphological evidence of condensed nuclei in the smooth cells on the surface of the embryonic disc. © 2010 Blackwell Verlag GmbH.

Relationships between root diameter, root length and root branching along lateral roots in adult, field-grown maize

PubMed Central

Wu, Qian; Pagès, Loïc; Wu, Jie

2016-01-01

Background and Aims Root diameter, especially apical diameter, plays an important role in root development and function. The variation in diameter between roots, and along roots, affects root structure and thus the root system’s overall foraging performance. However, the effect of diameter variation on root elongation, branching and topological connections has not been examined systematically in a population of high-order roots, nor along the roots, especially for mature plants grown in the field. Methods A method combining both excavation and analysis was applied to extract and quantify root architectural traits of adult, field-grown maize plants. The relationships between root diameter and other root architectural characteristics are analysed for two maize cultivars. Key Results The basal diameter of the lateral roots (orders 1–3) was highly variable. Basal diameter was partly determined by the diameter of the bearing segment. Basal diameter defined a potential root length, but the lengths of most roots fell far short of this. This was explained partly by differences in the pattern of diameter change along roots. Diameter tended to decrease along most roots, with the steepness of the gradient of decrease depending on basal diameter. The longest roots were those that maintained (or sometimes increased) their diameters during elongation. The branching density (cm–1) of laterals was also determined by the diameter of the bearing segment. However, the location of this bearing segment along the mother root was also involved – intermediate positions were associated with higher densities of laterals. Conclusions The method used here allows us to obtain very detailed records of the geometry and topology of a complex root system. Basal diameter and the pattern of diameter change along a root were associated with its final length. These relationships are especially useful in simulations of root elongation and branching in source–sink models. PMID:26744490

Analysis of Femoral Components of Cemented Total Hip Arthroplasty

NASA Astrophysics Data System (ADS)

Singh, Shantanu; Harsha, A. P.

2016-10-01

There have been continuous on-going revisions in design of prosthesis in Total Hip Arthroplasty (THA) to improve the endurance of hip replacement. In the present work, Finite Element Analysis was performed on cemented THA with CoCrMo trapezoidal, CoCrMo circular, Ti6Al4V trapezoidal and Ti6Al4V circular stem. It was observed that cross section and material of femoral stem proved to be critical parameters for stress distribution in femoral components, distribution of interfacial stress and micro movements. In the first part of analysis, designs were investigated for micro movements and stress developed, for different stem materials. Later part of the analysis focused on investigations with respect to different stem cross sections. Femoral stem made of Titanium alloy (Ti6Al4V) resulted in larger debonding of stem at cement-stem interface and increased stress within the cement mantle in contrast to chromium alloy (CoCrMo) stem. Thus, CoCrMo proved to be a better choice for cemented THA. Comparison between CoCrMo femoral stem of trapezium and circular cross section showed that trapezoidal stem experiences lesser sliding and debonding at interfaces than circular cross section stem. Also, trapezium cross section generated lower peak stress in femoral stem and cortical femur. In present study, femur head with diameter of 36 mm was considered for the analysis in order to avoid dislocation of the stem. Also, metallic femur head was coupled with cross linked polyethylene liner as it experiences negligible wear compared to conventional polyethylene liner and unlike metallic liner it is non carcinogenic.

Evolution of wood anatomical characters in Nepenthes and close relatives of Caryophyllales.

PubMed

Schwallier, Rachel; Gravendeel, Barbara; de Boer, Hugo; Nylinder, Stephan; van Heuven, Bertie Joan; Sieder, Anton; Sumail, Sukaibin; van Vugt, Rogier; Lens, Frederic

2017-05-01

Nepenthes attracts wide attention with its spectacularly shaped carnivorous pitchers, cultural value and horticultural curiosity. Despite the plant's iconic fascination, surprisingly little anatomical detail is known about the genus beyond its modified leaf tip traps. Here, the wood anatomical diversity of Nepenthes is explored. This diversity is further assessed with a phylogenetic framework to investigate whether the wood characters within the genus are relevant from an evolutionary or ecological perspective, or rather depend on differences in developmental stages, growth habits, substrates or precipitation. Observations were performed using light microscopy and scanning electron microscopy. Ancestral states of selected wood and pith characters were reconstructed using an existing molecular phylogeny for Nepenthes and a broader Caryophyllales framework. Pairwise comparisons were assessed for possible relationships between wood anatomy and developmental stages, growth habits, substrates and ecology. Wood anatomy of Nepenthes is diffuse porous, with mainly solitary vessels showing simple, bordered perforation plates and alternate intervessel pits, fibres with distinctly bordered pits (occasionally septate), apotracheal axial parenchyma and co-occurring uni- and multiseriate rays often including silica bodies. Precipitation and growth habit (stem length) are linked with vessel density and multiseriate ray height, while soil type correlates with vessel diameter, vessel element length and maximum ray width. For Caryophyllales as a whole, silica grains, successive cambia and bordered perforation plates are the result of convergent evolution. Peculiar helical sculpturing patterns within various cell types occur uniquely within the insectivorous clade of non-core Caryophyllales. The wood anatomical variation in Nepenthes displays variation for some characters dependent on soil type, precipitation and stem length, but is largely conservative. The helical-banded fibre-sclereids that mainly occur idioblastically in pith and cortex are synapomorphic for Nepenthes , while other typical Nepenthes characters evolved convergently in different Caryophyllales lineages. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Elevated Genetic Diversity in an F2:6 Population of Quinoa (Chenopodium quinoa) Developed through an Inter-ecotype Cross

PubMed Central

Benlhabib, Ouafae; Boujartani, Noura; Maughan, Peter J.; Jacobsen, Sven E.; Jellen, Eric N.

2016-01-01

Quinoa (Chenopodium quinoa) is a seed crop of the Andean highlands and Araucanian coastal regions of South America that has recently expanded in use and production beyond its native range. This is largely due to its superb nutritional value, consisting of protein that is rich in essential amino acids along with vitamins and minerals. Quinoa also presents a remarkable degree of tolerance to saline conditions, drought, and frost. The present study involved 72 F2:6 recombinant-inbred lines and parents developed through hybridization between highland (0654) and coastal (NL-6) germplasm groups. The purpose was to characterize the quinoa germplasm developed, to assess the discriminating potential of 21 agro-morpho-phenological traits, and to evaluate the extent of genetic variability recovered through selfing. A vast amount of genetic variation was detected among the 72 lines evaluated for quantitative and qualitative traits. Impressive transgressive segregation was measured for seed yield (22.42 g/plant), while plant height and maturity had higher heritabilities (73 and 89%, respectively). Other notable characters segregating in the population included panicle and stem color, panicle form, and resistance to downy mildew. In the Principal Component analysis, the first axis explained 74% of the total variation and was correlated to plant height, panicle size, stem diameter, biomass, mildew reaction, maturation, and seed yield; those traits are relevant discriminatory characters. Yield correlated positively with panicle length and biomass. Unweighted Pair Group Method with Arithmetic Mean-based cluster analysis identified three groups: one consisting of late, mildew-resistant, high-yielding lines; one having semi-late lines with intermediate yield and mildew susceptibility; and a third cluster consisting of early to semi-late accessions with low yield and mildew susceptibility. This study highlighted the extended diversity regenerated among the 72 accessions and helped to identify potentially adapted quinoa genotypes for production in the Moroccan coastal environment. PMID:27582753

Evolution of wood anatomical characters in Nepenthes and close relatives of Caryophyllales

PubMed Central

Gravendeel, Barbara; de Boer, Hugo; Nylinder, Stephan; van Heuven, Bertie Joan; Sieder, Anton; Sumail, Sukaibin; van Vugt, Rogier; Lens, Frederic

2017-01-01

Abstract Background and Aims Nepenthes attracts wide attention with its spectacularly shaped carnivorous pitchers, cultural value and horticultural curiosity. Despite the plant’s iconic fascination, surprisingly little anatomical detail is known about the genus beyond its modified leaf tip traps. Here, the wood anatomical diversity of Nepenthes is explored. This diversity is further assessed with a phylogenetic framework to investigate whether the wood characters within the genus are relevant from an evolutionary or ecological perspective, or rather depend on differences in developmental stages, growth habits, substrates or precipitation. Methods Observations were performed using light microscopy and scanning electron microscopy. Ancestral states of selected wood and pith characters were reconstructed using an existing molecular phylogeny for Nepenthes and a broader Caryophyllales framework. Pairwise comparisons were assessed for possible relationships between wood anatomy and developmental stages, growth habits, substrates and ecology. Key Results Wood anatomy of Nepenthes is diffuse porous, with mainly solitary vessels showing simple, bordered perforation plates and alternate intervessel pits, fibres with distinctly bordered pits (occasionally septate), apotracheal axial parenchyma and co-occurring uni- and multiseriate rays often including silica bodies. Precipitation and growth habit (stem length) are linked with vessel density and multiseriate ray height, while soil type correlates with vessel diameter, vessel element length and maximum ray width. For Caryophyllales as a whole, silica grains, successive cambia and bordered perforation plates are the result of convergent evolution. Peculiar helical sculpturing patterns within various cell types occur uniquely within the insectivorous clade of non-core Caryophyllales. Conclusions The wood anatomical variation in Nepenthes displays variation for some characters dependent on soil type, precipitation and stem length, but is largely conservative. The helical-banded fibre-sclereids that mainly occur idioblastically in pith and cortex are synapomorphic for Nepenthes, while other typical Nepenthes characters evolved convergently in different Caryophyllales lineages. PMID:28387789

The special features of tree ring gas chronologies

NASA Astrophysics Data System (ADS)

Ageev, Boris G.; Gruzdev, Aleksandr N.; Sapozhnikova, Valeria A.

2015-11-01

Stem wood is known to contain significant amounts of gases. However, literature data on the functional role of the gases are lacking. The results of our experiments show that porous wood structure is capable of annual accumulation (sorption) of the stem gas components that include H2O vapor and plant cell-respired CO2. This allows for development of additional chronologies to be used for gaining a deeper insight into the behavior of the stem gases. An analysis of the vacuum-extracted wood tree ring CO2 and H2O has revealed that the CO2 and H2O chronologies are associated with interannual variations in the total pressure of the gas components in the tree rings and are characterized by short-period cycles independent of tree age and by long-period variations with tree age. Our investigations led us to propose a procedure for using the CO2 content as a marker of year-to-year variations in the total pressure of the residual gas components found in wood tree rings.

Revision hip arthroplasty with an extensively 
porous-coated stem - excellent long-term 
results also in severe femoral bone stock loss.

PubMed

Thomsen, Per B; Jensen, Niels J F; Kampmann, Jens; Bæk Hansen, Torben

2013-01-01

During the last 25 years uncemented hip stem revision relying on diaphyseal fixation has shown improving clinical results and stem survival. The purpose of this study was to present the long-term results of hip revision with the SOLUTION stem (DePuy, Warsaw Indiana).
Ninety-three consecutive SOLUTION hip stem revisions in 84 patients with a mean age of 69 years (range 33-86 years) were reviewed. Of these, clinical and radiographic follow-up examination by an independent observer was possible in 36 hips/29 patients after mean 14 years (range 10-18 years). Stem re-revision was documented by our own files and by the Danish Hip Arthroplasty Registry. 
Stem re-revision had been performed in two hips for aseptic loosening, one due to deep infection and in one patient due to stem fracture. The 18 years cumulative survival, free of re-revision for any reason was calculated as 94.4% (88.9-99.8)% and for aseptic loosening to 97.6% (94.3-100%). Intraoperative complications were frequent with incidence of shaft fractures (14/93) and perforations (9/93) showing a significant learning curve. Mean Harris Hip Score was 85 (range 53-99). Osseointegration was seen in 34/36 stems with two stems fibrous fixated. Stress shielding was significant associated with stem diameters ≥15 mm. Severe preoperative bone deficiency had no negative bearing on stem survival and no significant influence on osseointegration of the stem or on Harris Hip Score. 
 Femoral stem revision with an extensively porous-coated monoblock chrome-cobalt stem seems to be a reliable and reproducible technique resulting in excellent long-term survivorship and clinical outcome. It can be used in femurs with deficient bone stock.

Assessment of the Effect of Blast Hole Diameter on the Number of Oversize Boulders Using ANN Model

NASA Astrophysics Data System (ADS)

Dhekne, Prakash; Pradhan, Manoj; Jade, Ravi Krishnarao

2016-04-01

Now-a-days, blasts are planned using large diameter blast holes. The loading density (kg/m) and subsequently the energy available for the breakage of the rockmass increase with the diameter. The in-hole velocity of detonation (VoD) of non-ideal explosive also boosts up with the increase in diameter till the optimum diameter is reached. The increase in the energy content and in-hole VoD cause a sizable effect on the rock fragmentation. The effect can be assessed by counting the number of oversize boulders. This paper explains as to how the technique of artificial neural network modeling was used to predict the number of oversize boulders resulting from ANFO and SME blasts with blast holes of different diameters. The results from ANFO blasts indicated that there was no significant variation in the number of oversize boulders with the diameter whereas a perceptible variation was noticed in case of SME blasts with the change in the diameter. The change in the number of oversize boulders in ANFO blasts was negligible because mean energy factor remained almost same even when the diameter of the blast holes was altered. The decrease in the number of oversize boulders in SME blasts was on account of increase in mean energy factor when the blast hole diameter was increased. The increase in the in-hole VoD due to increase in the diameter of the hole was not found to have an effect on the generation of oversize boulders as this increase was not substantial both in SME and ANFO blasts.

Single-cell sequencing in stem cell biology.

PubMed

Wen, Lu; Tang, Fuchou

2016-04-15

Cell-to-cell variation and heterogeneity are fundamental and intrinsic characteristics of stem cell populations, but these differences are masked when bulk cells are used for omic analysis. Single-cell sequencing technologies serve as powerful tools to dissect cellular heterogeneity comprehensively and to identify distinct phenotypic cell types, even within a 'homogeneous' stem cell population. These technologies, including single-cell genome, epigenome, and transcriptome sequencing technologies, have been developing rapidly in recent years. The application of these methods to different types of stem cells, including pluripotent stem cells and tissue-specific stem cells, has led to exciting new findings in the stem cell field. In this review, we discuss the recent progress as well as future perspectives in the methodologies and applications of single-cell omic sequencing technologies.

Comparison of Stem Map Developed from Crown Geometry Allometry Linked Census Data to Airborne and Terrestrial Lidar at Harvard Forest, MA

NASA Astrophysics Data System (ADS)

Sullivan, F.; Palace, M. W.; Ducey, M. J.; David, O.; Cook, B. D.; Lepine, L. C.

2014-12-01

Harvard Forest in Petersham, MA, USA is the location of one of the temperate forest plots established by the Center for Tropical Forest Science (CTFS) as a joint effort with Harvard Forest and the Smithsonian Institute's Forest Global Earth Observatory (ForestGEO) to characterize ecosystem processes and forest dynamics. Census of a 35 ha plot on Prospect Hill was completed during the winter of 2014 by researchers at Harvard Forest. Census data were collected according to CTFS protocol; measured variables included species, stem diameter, and relative X-Y locations. Airborne lidar data were collected over the censused plot using the high spatial resolution Goddard LiDAR, Hyperspectral, and Thermal sensor package (G-LiHT) during June 2012. As part of a separate study, 39 variable radius plots (VRPs) were randomly located and sampled within and throughout the Prospect Hill CTFS/ForestGEO plot during September and October 2013. On VRPs, biometric properties of trees were sampled, including species, stem diameter, total height, crown base height, crown radii, and relative location to plot centers using a 20 Basal Area Factor prism. In addition, a terrestrial-based lidar scanner was used to collect one lidar scan at plot center for 38 of the 39 VRPs. Leveraging allometric equations of crown geometry and tree height developed from 374 trees and 16 different species sampled on 39 VRPs, a 3-dimensional stem map will be created using the Harvard Forest ForestGEO Prospect Hill census. Vertical and horizontal structure of 3d field-based stem maps will be compared to terrestrial and airborne lidar scan data. Furthermore, to assess the quality of allometric equations, a 2d canopy height raster of the field-based stem map will be compared to a G-LiHT derived canopy height model for the 35 ha census plot. Our automated crown delineation methods will be applied to the 2d representation of the census stem map and the G-LiHT canopy height model. For future work related to this study, high quality field-based stem maps with species and crown geometry information will allow for better comparisons and interpretations of individual tree spectra from the G-LiHT hyperspectral sensor as estimated by automated crown delineation of the G-LiHT lidar canopy height model.

Micropropagation of Gerbera (Gerbera jamesonii Bolus).

PubMed

Minerva, Ghani; Kumar, Surinder

2013-01-01

Gerbera (Gerbera jamesonii Bolus) is one of the most popular ornamental flowers worldwide and used both as cut flower and potted plant. Some of them show excellent agronomic characters such as color, floral diameter, stem length, and vigor, which make this plant of commercial importance. Conventionally, multiplication is done through seeds or rhizome cuttings. Rapid multiplication of elite cultivars of Gerbera, with improved agronomic traits, has been achieved by using both direct and indirect tissue culture methods. Direct shoot regeneration was accomplished from stem apices on MS medium supplemented with 1 mg/L 6-benzyladenine (BA) and 1 mg/L kinetin. Indirect shoot induction succeeded from callus differentiation has been achieved on MS medium containing 2 mg/L 2,4-dichlorophenoxyacetic acid, 0.5 mg/L indole-3-acetic acid, and 2 mg/L BA. The in vitro shoots, 4-5 cm long, were rooted by quick dipping the shoot bases for 3-5 s in 2,000 mg/L indole-3-butyric acid solution followed by transfer to the pots containing farmyard manure, soil, and sand (1:1:1 by volume). Initially, in vitro plantlets were covered with glass jars to maintain a high relative humidity (85-90%). As soon as new shoot growth begins, relative humidity is decreased by exposing them to the open environmental conditions prior transferring to the glasshouse. Indirect shoot regeneration increased the frequency of somaclonal variations. The selected somaclones were used in developing new and novel cultivars.

Performance Testing of Thermal Cutting Systems for Sweet Pepper Harvesting Robot in Greenhouse Horticulture

NASA Astrophysics Data System (ADS)

Bachche, Shivaji; Oka, Koichi

2013-03-01

This paper proposes design of end-effector and prototype of thermal cutting system for harvesting sweet peppers. The design consists of two parallel gripper bars mounted on a frame connected by specially designed notch plate and operated by servo motor. Based on voltage and current, two different types of thermal cutting system prototypes; electric arc and temperature arc respectively were developed and tested for performance. In electric arc, a special electric device was developed to obtain high voltage to perform cutting operation. At higher voltage, electrodes generate thermal arc which helps to cut stem of sweet pepper. In temperature arc, nichrome wire was mounted between two electrodes and current was provided directly to electrodes which results in generation of high temperature arc between two electrodes that help to perform cutting operation. In both prototypes, diameters of basic elements were varied and the effect of this variation on cutting operation was investigated. The temperature arc thermal system was found significantly suitable for cutting operation than electric arc thermal system. In temperature arc thermal cutting system, 0.5 mm nichrome wire shows significant results by accomplishing harvesting operation in 1.5 seconds. Also, thermal cutting system found suitable to increase shelf life of fruits by avoiding virus and fungal transformation during cutting process and sealing the fruit stem. The harvested sweet peppers by thermal cutting system can be preserved at normal room temperature for more than 15 days without any contamination.

Whole exome sequencing to estimate alloreactivity potential between donors and recipients in stem cell transplantation

PubMed Central

Sampson, Juliana K.; Sheth, Nihar U.; Koparde, Vishal N.; Scalora, Allison F.; Serrano, Myrna G.; Lee, Vladimir; Roberts, Catherine H.; Jameson-Lee, Max; Ferreira-Gonzalez, Andrea; Manjili, Masoud H.; Buck, Gregory A.; Neale, Michael C.; Toor, Amir A.

2016-01-01

Summary Whole exome sequencing (WES) was performed on stem cell transplant donor-recipient (D-R) pairs to determine the extent of potential antigenic variation at a molecular level. In a small cohort of D-R pairs, a high frequency of sequence variation was observed between the donor and recipient exomes independent of human leucocyte antigen (HLA) matching. Nonsynonymous, nonconservative single nucleotide polymorphisms were approximately twice as frequent in HLA-matched unrelated, compared with related D-R pairs. When mapped to individual chromosomes, these polymorphic nucleotides were uniformly distributed across the entire exome. In conclusion, WES reveals extensive nucleotide sequence variation in the exomes of HLA-matched donors and recipients. PMID:24749631

7 CFR 51.3416 - Classification of defects.

Code of Federal Regulations, 2011 CFR

2011-01-01

... ring Internal Black Spot, Internal Discoloration, Vascular Browning, Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5% waste 10% waste. Occurring entirely within the vascular ring Hollow Heart or... diameter in a 10 ounce potato. 1 Internal Brown Spot and similar discoloration (Heat Necrosis) Not more...

7 CFR 51.3416 - Classification of defects.

Code of Federal Regulations, 2012 CFR

2012-01-01

... ring Internal Black Spot, Internal Discoloration, Vascular Browning, Fusarium Wilt, Net Necrosis, Other Necrosis, Stem End Browning 5% waste 10% waste. Occurring entirely within the vascular ring Hollow Heart or... diameter in a 10 ounce potato. 1 Internal Brown Spot and similar discoloration (Heat Necrosis) Not more...

Regeneration dynamics during oak decline with prescribed fire in the Boston Mountains of Arkansas

Treesearch

Martin A. Spetich

2013-01-01

Northern red oak (Quercus rubra L.) seedlings were inventoried in 2000 and again in 2005 to better understand survival of advance regeneration during oak decline. In 2000, basal stem diameter was measured and recorded for 861 individually tagged seedlings that were

System among the Two-Stems.

ERIC Educational Resources Information Center

Murphy, David T.

1984-01-01

Proposes a variation of the two-stem system of analyzing the Russian verb. The need for greater organization and systematization is stressed, as well as an increased focus on the great regularity of the Russian verb, and the relative simplicity of Russian verbal morphology. (SL)

Wood properties and trunk allometry of co-occurring rainforest canopy trees in a cyclone-prone environment.

PubMed

Read, Jennifer; Evans, Robert; Sanson, Gordon D; Kerr, Stuart; Jaffré, Tanguy

2011-11-01

New Caledonia commonly experiences cyclones, so trees there are expected to have enhanced wood traits and trunk allometry that confer resistance to wind damage. We ask whether there is evidence of a trade-off between these traits and growth rate among species. Wood traits, including density, microfibril angle (MFA), and modulus of elasticity (MOE), ratio of tree height to stem diameter, and growth rate were investigated in mature trees of 15 co-occurring canopy species in a New Caledonian rainforest. In contrast to some studies, wood density did not correlate negatively with growth increment. Among angiosperms, wood density and MOE correlated positively with diameter-adjusted tree height, and MOE correlated positively with stem-diameter growth increment. Tall slender trees achieved high stiffness with high efficiency with respect to wood density, in part by low MFA, and with a higher diameter growth increment but a lower buckling safety factor. However, some tree species of a similar niche differed in whole-tree resistance to wind damage and achieved wood stiffness in different ways. There was no evidence of a growth-safety trade-off in these trees. In forests that regularly experience cyclones, there may be stronger selection for high wood density and/or stiffness in fast-growing trees of the upper canopy, with the potential growth trade-off amortized by access to the upper canopy and by other plant traits. Furthermore, decreasing wood density does not necessarily decrease resistance to wind damage, resistance being influenced by other characteristics including cell-level traits (e.g., MFA) and whole-plant architecture.

Cambial variations of Piper (Piperaceae) in Taiwan.

PubMed

Yang, Sheng-Zehn; Chen, Po-Hao

2017-12-01

Cambial variations in lianas of Piperaceae in Taiwan have not been studied previously. The stem anatomy of seven Piper species from Taiwan was examined to document cambial variations and better distinguish the species when leaves are absent. A key for the seven species is provided, based on the internal stem anatomy. The seven Piper species climb via adventitious roots, and in cross section, the stems were generally eccentric and oblate, although a transversely elliptic stem was found in P. kadsura (Choisy) Ohwi and P. sintenense Hatus. A cambial variant with secondary growth of external primary vascular bundles and xylem in plates was observed in all species except Piper betle L., which developed another cambium variant with xylem furrowed deeply by parenchyma proliferation. The sclerenchymatous ring surrounding the medullary vascular bundles was always continuous except in P. betle, where it was discontinuous. Mucilage canals varied from absent to present in the center of the pith, or present in the pith and inner cortex. Different sizes of vessels dispersed throughout the stem were ring or diffuse porous. The numbers of medullary and peripheral vascular bundles were distinctive and the widths of rays were noticeably different in each species. Differences in the growth rate of the medullary vascular bundles produced two development types of vascular bundles, although in both types, the peripheral vascular bundles gradually lengthen and become separated from each other by wide rays. We documented the internal stem anatomy of six previously unstudied species of Piper, including three endemic species, P. kwashoense Hayata, P. sintenense, and P. taiwanense Lin and Lu, and found that P. betle had deeply furrowed xylem, which had not been reported for the species before. The descriptions and photographs of seven Piper species will also provide a basis for further morphological studies.

Glenoid version and size: does gender, ethnicity, or body size play a role?

PubMed

Piponov, Hristo Ivanov; Savin, David; Shah, Neal; Esposito, Domenic; Schwartz, Brian; Moretti, Vincent; Goldberg, Benjamin

2016-11-01

Variations in glenoid morphology among patients of different gender, body habitus, and ethnicity have been of interest for surgeons. Understanding these anatomical variations is a critical step in restoring normal glenohumeral structure during shoulder reconstruction surgery. Retrospective review of 108 patient shoulder CT scans was performed and glenoid version, AP diameter and height were measured. Statistical multiple regression models were used to investigate the ability of gender and ethnicity to predict glenoid AP diameter, height, and version independently of patient weight and height. The mean glenoid AP diameter was 24.7 ± 3.5, the mean glenoid height was 31.7 ± 3.7, and the mean glenoid version was 0.05 ± 9.05. According to our regression models, males would be expected to exhibit 8.4° more glenoid retroversion than females (p = 0.003) and have 2.9 mm larger glenoid height compared to females (p = 0.002). The predicted male glenoid AP diameter was 3.4 mm higher than that in females (p < 0.001). Hispanics demonstrated 6.4° more glenoid anteversion compared to African-Americans (p = 0.04). Asians exhibited 4.1 mm smaller glenoid AP diameters than African-Americans (p = 0.002). An increase of 25 kg in patient weight resulted in 1 mm increase in AP diameter (p = 0.01). Gender is the strongest independent predictor of glenoid size and version. Males exhibited a larger size and more retroverted glenoid. Patient height was found to be predictive of glenoid size only in patients of the same gender. Although variations in glenoid size and version are observed among ethnicities, larger sample size ethnic groups will be necessary to explore the precise relations. Surgeons should consider gender and ethnic variations in the pre-operative planning and surgical restoration of the native glenohumeral relationship. Anatomic Study.

Wood Anatomy and Insect Defoliator Systems: Is there an anatomical response to sustained feeding by the western spruce budworm (Choristoneura occidentalis) on Douglas-fir (Pseudotusga menziesii)?

NASA Astrophysics Data System (ADS)

Axelson, Jodi; Gärtner, Holger; Alfaro, René; Smith, Dan

2013-04-01

The western spruce budworm (Choristoneura occidentalis Freeman) is the most widespread and destructive defoliator of coniferous forests in western North America, and has a long-term coexistence with its primary host tree, Douglas-fir (Pseudotsuga menziesii Franco). Western spruce budworm (WSB) outbreaks usually last for several years, and cause reductions in annual growth, stem defects, and regeneration delays. In British Columbia, the WSB is the second most damaging insect after the mountain pine beetle, and sustained and/or severe defoliation can result in the mortality of host trees. Numerous studies have used tree rings to reconstruct WSB outbreaks across long temporal scales, to evaluate losses in stand productivity, and examine isotope ratios. Although some studies have looked at the impacts of artificial defoliation on balsam fir in eastern North America, there has been no prior research on how WSB outbreaks affect the anatomical structure of the stem as described by intra-annual wood density and potential cell size variations. The objective of this study was to anatomically examine the response of Douglas-fir to sustained WSB outbreaks in two regions of southern British Columbia. We hypothesize that the anatomical intra-annual characteristics of the tree rings, such as cell wall thickness, latewood cell size, and/or lumen area changes during sustained WSB outbreaks. To test this hypothesis we sampled four permanent sample plots in coastal and dry interior sites, which had annually resolved defoliation data collected over a 7-12 year period. At each site diameter-at-breast height (cm), height (m), and crown position were recorded and three increment cores were extracted from 25 trees. Increment cores were prepared to permit anatomical and x-ray density analyses. For each tree, a 15µm thick micro section was cut from the radial plane. Digital images of the micro sections were captured and processed. In each annual ring, features such as cell lumen area (µm2), cell wall thickness (µm), lumen diameter (µm), and total cell width (µm) were measured. Preliminary results indicate that earlywood parameters remain quite stable during WSB outbreak, while latewood parameters such as secondary cell wall thickness and cell length undergo step shifts at the beginning and end of outbreaks. These parameters, tree-level data, and annual defoliation data will further be tested to determine if changes in stem wood anatomy during WSB outbreaks were statistically significant.

Laser-induced retinal injury thresholds: variation with retinal irradiated area

NASA Astrophysics Data System (ADS)

Lund, David J.; Schulmeister, Karl; Seiser, Bernhard; Edthofer, Florian

2005-04-01

The retinal injury threshold for exposure to a laser source varies as a function of the irradiated area on the retina. Currently accepted guidelines for the safe use of lasers provide that the MPE will increase as the diameter of the irradiated area for retinal diameters between 25 mm and 1700 mm, based on the ED50 data available in the late 1970s. Recent studies by Zuclich and Lund produced data showing that the ED50 for ns-duration exposures at 532 nm and ms duration exposures at 590 nm varied as the square of the diameter of the irradiated area on the retina. This paper will discuss efforts to resolve the disagreement between the new data and the earlier data though an analysis of all accessible data relating the retinal injury threshold to the diameter of the incident beam on the retina and through simulations using computer models of laser-induced injury. The results show that the retinal radiant exposure required to produce retinal injury is a function of both exposure duration and retinal irradiance diameter and that the current guidelines for irradiance diameter dependence do not accurately reflect the variation of the threshold data.

Mean Normal Portal Vein Diameter Using Sonography among Clients Coming to Radiology Department of Jimma University Hospital, Southwest Ethiopia.

PubMed

Geleto, Gemechu; Getnet, Wondim; Tewelde, Tsegaye

2016-05-01

Mean portal vein diameter is considered as the best indicator for portal hypertension. However, the cutoff point differs from study to study (above 10-15 mm) despite the existence of normal mean portal vein diameter between 10-15 mm in different settings.This implies the existence of limited evidence on normal portal vein diameter for all populations in all countries prior to setting the cutoff points. Therefore, the aim of this study was sonographic assessment of normal mean portal vein diameter among patients referred to The Department of Radiology in Jimma University Hospital. A facility based cross-sectional study was conducted from November to December 2014 at Jimma University Hospital on a total of 195 clients. Data about portal vein diameter for eligible clients were collected by radiologists using Sonography. Data were edited manually, entered and analyzed using SPSS version 16. Data were collected from a total of 195 participants. Among these, 121(62.1%) were males and the median age of the participants was 35 years. The study revealed a normal mean portal vein diameter of 10.6 mm ±1.8 SD with a respirophasic variation of 25.6%. Likewise, the normal mean portal vein diameter seemed to have varied significantly by age and sex. The study revealed a normal mean portal vein diameter ranging below 13 mm. Hence, decisions made in clinical settings should base on these findings. Besides, there is a need for large scale study to determine portal vein diameter variation by age and sex, controlling other confounders.

The structure of the stem endodermis in etiolated pea seedlings

NASA Technical Reports Server (NTRS)

Sack, F. D.

1987-01-01

Differentiation of the endodermis was examined in third internodes of etiolated Pisum sativum L. cv. Alaska seedlings. The endodermis in young internodes contains large, sedimented amyloplasts; in older internodes, a casparian strip differentiates and the endodermis becomes depleted of starch except for the proximal region of the stem, which retains sedimented amyloplasts and remains graviresponsive. Sedimentation occurs in the hook but does not occur consistently until cells reach the base of the hook, where the axis becomes vertical, rapid cell elongation starts, and amyloplast diameter increases substantially. Contact between endoplasmic reticulum and amyloplasts was observed. Endoplasmic reticulum is not distributed polarly with respect to gravity. No symplastic or apoplastic blockages exist in the endodermis at the level of the stem where lateral gradients may be established during tropic curvature.

Total Hip Arthroplasty Using a Polished Tapered Cemented Stem in Hereditary Multiple Exostosis

PubMed Central

Kanda, Akio; Kaneko, Kazuo; Obayashi, Osamu; Mogami, Atsuhiko

2016-01-01

A 61-year-old Japanese man underwent right total hip arthroplasty for hereditary multiple exostosis. At first presentation, he had suffered from coxalgia for a long time. On radiographic images, there was a gigantic femoral head, increased shaft angle, and large diameter of the femoral neck. He had also developed coxarthrosis and severe pain of the hip joint. The transformation of the proximal femur bone causes difficulty in setting a cementless total hip prosthesis. Therefore, total hip arthroplasty using a cemented polished tapered stem was performed via a direct lateral approach. Using a cemented polished tapered stem allowed us to deal with the femoral bone transformation and bone substance defectiveness due to exostosis and also minimized the invasiveness of the operation. PMID:27127668

Impact of retrotransposons in pluripotent stem cells.

PubMed

Tanaka, Yoshiaki; Chung, Leeyup; Park, In-Hyun

2012-12-01

Retrotransposons, which constitute approximately 40% of the human genome, have the capacity to 'jump' across the genome. Their mobility contributes to oncogenesis, evolution, and genomic plasticity of the host genome. Induced pluripotent stem cells as well as embryonic stem cells are more susceptible than differentiated cells to genomic aberrations including insertion, deletion and duplication. Recent studies have revealed specific behaviors of retrotransposons in pluripotent cells. Here, we review recent progress in understanding retrotransposons and provide a perspective on the relationship between retrotransposons and genomic variation in pluripotent stem cells.

Nanotopography Promotes Pancreatic Differentiation of Human Embryonic Stem Cells and Induced Pluripotent Stem Cells.

PubMed

Kim, Jong Hyun; Kim, Hyung Woo; Cha, Kyoung Je; Han, Jiyou; Jang, Yu Jin; Kim, Dong Sung; Kim, Jong-Hoon

2016-03-22

Although previous studies suggest that nanotopographical features influence properties and behaviors of stem cells, only a few studies have attempted to derive clinically useful somatic cells from human pluripotent stem cells using nanopatterned surfaces. In the present study, we report that polystyrene nanopore-patterned surfaces significantly promote the pancreatic differentiation of human embryonic and induced pluripotent stem cells. We compared different diameters of nanopores and showed that 200 nm nanopore-patterned surfaces highly upregulated the expression of PDX1, a critical transcription factor for pancreatic development, leading to an approximately 3-fold increase in the percentage of differentiating PDX1(+) pancreatic progenitors compared with control flat surfaces. Furthermore, in the presence of biochemical factors, 200 nm nanopore-patterned surfaces profoundly enhanced the derivation of pancreatic endocrine cells producing insulin, glucagon, or somatostatin. We also demonstrate that nanopore-patterned surface-induced upregulation of PDX1 is associated with downregulation of TAZ, suggesting the potential role of TAZ in nanopore-patterned surface-mediated mechanotransduction. Our study suggests that appropriate cytokine treatments combined with nanotopographical stimulation could be a powerful tool for deriving a high purity of desired cells from human pluripotent stem cells.

Shrub Nesting of the Red-Eyed Vireo in Relation to Structure of Aspen Forests

Treesearch

William J. Jr Mattson

1979-01-01

Nests were built in five species of high shrubs in four trembling aspen forests of northern Minnesoa. Nest densities ranged between 0.5 and 3.0 per acre and were positively related to the abundance3 of large (>1.2-cm diameter) shrub stems.

Intertree competition in uneven-aged ponderosa pine stands

Treesearch

C.W. Woodall; C.E. Fiedler; K.S. Milner

2003-01-01

Intertree competition indices and effects were examined in 14 uneven-aged ponderosa pine (Pinus ponderosa var. scopulorum Engelm.) stands in eastern Montana. Location, height, diameter at breast height (DBH), basal area increment, crown ratio, and sapwood area were determined for each tree (DBH >3.8 cm) on one stem-mapped plot...

Restoring southern Ontario forests by managing succession in conifer plantations

Treesearch

William C. Parker; Ken A. Elliott; Daniel C. Dey; Eric Boysen

2008-01-01

Thinning and underplanting of conifer plantations to promote natural succession in southern Ontario's forests for restoration purposes was examined in a young red pine (Pinus resinosa Ait.) plantation. Eleven years after application of five thinning treatments, seedling diameter, height, and stem volume of planted white ash (Fraxinus...

Tree height and tropical forest biomass estimation

Treesearch

M.O. Hunter; M. Keller; D. Vitoria; D.C. Morton

2013-01-01

Tropical forests account for approximately half of above-ground carbon stored in global vegetation. However, uncertainties in tropical forest carbon stocks remain high because it is costly and laborious to quantify standing carbon stocks. Carbon stocks of tropical forests are determined using allometric relations between tree stem diameter and height and biomass....

Transpiration characteristics of a rubber plantation in central Cambodia.

PubMed

Kobayashi, Nakako; Kumagai, Tomo'omi; Miyazawa, Yoshiyuki; Matsumoto, Kazuho; Tateishi, Makiko; Lim, Tiva K; Mudd, Ryan G; Ziegler, Alan D; Giambelluca, Thomas W; Yin, Song

2014-03-01

The rapid and widespread expansion of rubber plantations in Southeast Asia necessitates a greater understanding of tree physiology and the impacts of water consumption on local hydrology. Sap flow measurements were used to study the intra- and inter-annual variations in transpiration rate (Et) in a rubber stand in the low-elevation plain of central Cambodia. Mean stand sap flux density (JS) indicates that rubber trees actively transpire in the rainy season, but become inactive in the dry season. A sharp, brief drop in JS occurred simultaneously with leaf shedding in the middle of the dry season in January. Although the annual maxima of JS were approximately the same in the two study years, the maximum daily stand Et of ∼2.0 mm day(-1) in 2010 increased to ∼2.4 mm day(-1) in 2011. Canopy-level stomatal response was well explained by changes in solar radiation, vapor pressure deficit, soil moisture availability, leaf area, and stem diameter. Rubber trees had a relatively small potential to transpire at the beginning of the study period, compared with average diffuse-porous species. After 2 years of growth in stem diameter, transpiration potential was comparable to other species. The sensitivity of canopy conductance (gc) to atmospheric drought indicates isohydric behavior of rubber trees. Modeling also predicted a relatively small sensitivity of gc to the soil moisture deficit and a rapid decrease in gc under extreme drought conditions. However, annual observations suggest the possibility of a change in leaf characteristics with tree maturity and/or initiation of latex tapping. The estimated annual stand Et was 469 mm year(-1) in 2010, increasing to 658 mm year(-1) in 2011. Diagnostic analysis using the derived gc model showed that inter-annual change in stand Et in the rapidly growing young rubber stand was determined mainly by tree growth rate, not by differences in air and soil variables in the surrounding environment. Future research should focus on the potentially broad applicability of the relationship between Et and tree size as well as environmental factors at stands different in terms of clonal type and age.

Photosynthetic, hydraulic and biomechanical responses of Juglans californica shoots to wildfire.

PubMed

Utsumi, Yasuhiro; Bobich, Edward G; Ewers, Frank W

2010-10-01

Leaf gas exchange and stem xylem hydraulic and mechanical properties were studied for unburned adults and resprouting burned Juglans californica (southern California black walnut) trees 1 year after a fire to explore possible trade-offs between mechanical and hydraulic properties of plants. The CO(2) uptake rates and stomatal conductance were 2-3 times greater for resprouting trees than for unburned adults. Both predawn and midday water potentials were more negative for unburned adult trees, indicating that the stems were experiencing greater water stress than the stems of resprouting trees. In addition, the xylem specific conductivity was similar in the two growth forms, even though the stems of resprouting trees were less vulnerable to water-stress-induced embolism than similar diameter, but older, stems of adult trees. The reduced vulnerability may have been due to less cavitation fatigue in stems of resprouts. The modulus of elasticity, modulus of rupture and xylem density were all greater for resprouts, indicating that resprouts have greater mechanical strength than do adult trees. The data suggest that there is no trade-off between stem mechanical strength and shoot hydraulic and photosynthetic efficiency in resprouts, which may have implications for the success of this species in the fire-prone plant communities of southern California.

Effects of umbilical cord blood stem cells on healing factors for diabetic foot injuries.

PubMed

Çil, N; Oğuz, E O; Mete, E; Çetinkaya, A; Mete, G A

2017-01-01

The use of stem or progenitor cells from bone marrow, or peripheral or umbilical cord blood is becoming more common for treatment of diabetic foot problems. These cells promote neovascularization by angiogenic factors and they promote epithelium formation by stimulating cell replication and migration under certain pathological conditions. We investigated the role of CD34 + stem cells from human umbilical cord blood in wound healing using a rat model. Rats were randomly divided into a control group and two groups with diabetes induced by a single dose of 55 mg/kg intraperitoneal streptozocin. Scarred areas 5 mm in diameter were created on the feet of all rats. The diabetic rats constituted the diabetes control group and a diabetes + stem cell group with local injection into the wound site of 0.5 × 106 CD34 + stem cells from human umbilical cord blood. The newly formed skin in the foot wounds following CD34 + stem cell treatment showed significantly improvement by immunohistochemistry and TUNEL staining, and were closer to the wound healing of the control group than the untreated diabetic animals. The increase in FGF expression that accompanied the local injection of CD34 + stem cells indicates that FGF stimulation helped prevent apoptosis. Our findings suggest a promising new treatment approach to diabetic wound healing.

The effect of stem surface treatment and material on pistoning of ulnar components in linked cemented elbow prostheses.

PubMed

Hosein, Yara K; King, Graham J W; Dunning, Cynthia E

2013-09-01

The ulnar component of a total elbow replacement can fail by "pistoning." Stem surface treatments have improved stability at the stem-cement interface but with varied success. This study investigated the role of surface treatment and stem substrate material on implant stability under axial loading. Sixty circular stems (diameter, 8 mm) made of cobalt chrome (n = 30) or titanium (n = 30) had different surfaces: smooth, sintered beads, and plasma spray. The surface treatment length was either 10 mm or 20 mm. Stems were potted in bone cement, allowed to cure for 24 hours, and tested in a materials testing machine under a compressive staircase loading protocol. Failure was defined as 2 mm of push-out or completion of the protocol. Two-way analyses of variance compared the effects of surface treatment and substrate material on interface strength and motion. Significant interactions were found between surface treatment and substrate material for both interface strength and motion (P < .05). For titanium, the 20-mm beaded stems had greater interface strength than all other stems (P < .05) and had less motion than the 10-mm plasma-spray and smooth stems (P < .05). For cobalt chrome, the 20-mm beaded stems showed greater interface strength (P < .05) and similar motion (P > .05) to the 20-mm plasma-spray stems (P < .05), which outperformed all other stems (P < .05). Mechanisms of catastrophic failure varied: smooth stems debonded at the stem-cement interface, beaded stems experienced debonding of the beads from the stem, and plasma-spray stems showed loss of frictional force between the surface treatment and cement. Stem surface treatment can enhance ulnar component stability but is dependent on substrate material. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Life-history perspective of adaptive radiation in desmognathine salamanders

Treesearch

Richard C. Bruce

1996-01-01

This study investigates interspecific variation in age at first reproduction, fecundity, and body size in multispecies assemblages of desmognathine salamanders. The hypotheses tested are that interspecific differences in body size among desmognathines stem proximately from variation in age at first reproduction and that variation in the latter trait is positively...

Conduit grinding apparatus

DOEpatents

Nachbar, Henry D.; Korytkowski, Alfred S.

1991-01-01

A grinding apparatus for grinding the interior portion of a valve stem receiving area of a valve. The apparatus comprises a faceplate, a plurality of cams mounted to an interior face of the faceplate, a locking bolt to lock the faceplate at a predetermined position on the valve, a movable grinder and a guide tube for positioning an optical viewer proximate the area to be grinded. The apparatus can either be rotated about the valve for grinding an area of the inner diameter of a valve stem receiving area or locked at a predetermined position to grind a specific point in the receiving area.

Geotechnical Implications for the use of Alfalfa in Experimental Studies of Alluvial-Channel Morphology and Planform

NASA Astrophysics Data System (ADS)

Pollen, N.; Simon, A.

2006-12-01

Research on the interactions between vegetation and channel flow dynamics has shown that vegetation is an important control on river morphology and planform. Increased vegetation density is commonly linked to a decrease in bank erosion and lateral migration rates. Roots add to bank strength through the production of a reinforced soil-root matrix, and vegetation can also act to increase bank stability through its hydrological effects, including canopy interception, and removal of soil water through evapotranspiration. Flow dynamics are also affected by vegetation, with a number of studies showing a linkage between vegetation density and width- depth-velocity relations and bank roughness. To evaluate the effects of vegetation on channel morphology and planform, several experimental studies in flumes have used alfalfa sprouts (Medicago sativa) to seed the bed and banks of experimental channels. In such studies, the effects of vegetation are accounted for by qualitatively increasing the resistance of the bank material to lateral erosion. However, the material properties of alfalfa roots and stems, and the actual increase in resistance provided to the banks under different densities of alfalfa have thus far been ignored. To quantify this added erosion resistance, alfalfa sprouts were grown for 7 to 21 days, in sand with a d50 of 0.23 mm. At regular intervals, roots and stems were tested to measure tensile strength and forces required for pullout. Results of the tensile-strength measurements display the typical non-linear decrease of tensile strength (in MPa) with increasing root diameter but the curve is shifted to the left (weaker for a given diameter) of other riparian species. However, to calculate the increase in bank cohesion due to alfalfa roots, it is necessary to also account for the number of roots, and the distribution of different root diameters. The number of roots was calculated for a range of stem densities (0 to 10 stems/cm2), assuming a single, un-branching root per stem. Values for the additional cohesion provided by the alfalfa roots were calculated using the root- reinforcement model, RipRoot, producing values of 0 to 11.8 kPa. These results provide a means of quantifying the additional bank resistance provided to experimental channels under different stem/root densities. Cohesion values obtained in this way were successfully related to studies of braiding intensity published by others. The geometric properties of alfalfa scale up from experiments in flumes to approximate young trees on a floodplain. However, soil properties such as cohesion cannot be scaled. As such, the cohesion values due to roots calculated here represent the actual magnitude of reinforcement provided, rather than a scaled value.

Thigmomorphogenesis: anatomical, morphological and mechanical analysis of genetically different sibs of Pinus taeda in response to mechanical perturbation.

PubMed

Telewski, F W; Jaffe, M J

1986-01-01

Twenty-three open pollinated families (half-sibs) and four controlled pollinated families (full-sibs) of Pinus taeda L. (loblolly pine) were grown in a greenhouse and analyzed for changes induced by mechanical perturbation (MP). These changes included inhibition of stem and needle elongation, bracing of branch nodes, and increased radial growth in the direction of the MP. Inhibition of stem elongation was the least variable feature measured. Leaf extension and stem diameter were highly variable between half-sibs. MP induced increased drag in greenhouse grown P. taeda in wind-tunnel tests. In P. taeda, MP induced decreased flexibility and increased elasticity and plasticity of the stem. The increased radial growth of the stems overrode the increase in elasticity, resulting in an overall decrease in flexibility. MP trees had a higher rupture point than non-MP controls. Increased radial growth is a result of more rapid cell divisions of the vascular cambium, resulting in increased numbers of tracheids. The decreased leader growth is partly due to a decreased tracheid length in response to MP.

Thigmomorphogenesis: anatomical, morphological and mechanical analysis of genetically different sibs of Pinus taeda in response to mechanical perturbation

NASA Technical Reports Server (NTRS)

Telewski, F. W.; Jaffe, M. J.

1986-01-01

Twenty-three open pollinated families (half-sibs) and four controlled pollinated families (full-sibs) of Pinus taeda L. (loblolly pine) were grown in a greenhouse and analyzed for changes induced by mechanical perturbation (MP). These changes included inhibition of stem and needle elongation, bracing of branch nodes, and increased radial growth in the direction of the MP. Inhibition of stem elongation was the least variable feature measured. Leaf extension and stem diameter were highly variable between half-sibs. MP induced increased drag in greenhouse grown P. taeda in wind-tunnel tests. In P. taeda, MP induced decreased flexibility and increased elasticity and plasticity of the stem. The increased radial growth of the stems overrode the increase in elasticity, resulting in an overall decrease in flexibility. MP trees had a higher rupture point than non-MP controls. Increased radial growth is a result of more rapid cell divisions of the vascular cambium, resulting in increased numbers of tracheids. The decreased leader growth is partly due to a decreased tracheid length in response to MP.

[Comparison of different harvest ways of Dendrobium officinale].

PubMed

Wang, Yang; Zhu, Yan; Si, Jin-Ping; Liu, Jing-Jing; Zhu, Yu-Qiu; Liu, Xiu-Juan

2015-03-01

To standardize the harvest ways of Dendrobium officinale and improve the quality and yield of D. officinale, a field experiment was carried out to study the effect of two kinds of harvest ways, which were keeping some of the axial shoot and harvesting all of the shoot by the end of the year. Then, the agronomic traits and yield were measured and the contents of polysaccharides and extractum were determined. The results showed that the harvest ways significantly affected the growth of D. officinale. Keeping some of the axial shoot could significantly improved the number of sprout, stem length, internode number and the internodal length, which also triggered increase the weight of fresh stems, leaves and the total of them and dry stems in per unit area, but it could not promote the stem diameter and the polysaccharide content in stems. Keeping some of the axial shoot moderately was conducive to the improvement of the production of medicinal materials in the process of harvesting by promoting the germination and growth of new buds, and to ensure the polysaccharide content by regulating the illumination and the density of cultivation.

Effects of Inflorescence Stem Structure and Cell Wall Components on the Mechanical Strength of Inflorescence Stem in Herbaceous Peony

PubMed Central

Zhao, Daqiu; Han, Chenxia; Tao, Jun; Wang, Jing; Hao, Zhaojun; Geng, Qingping; Du, Bei

2012-01-01

Herbaceous peony (Paeonia lactiflora Pall.) is a traditional famous flower, but its poor inflorescence stem quality seriously constrains the development of the cut flower. Mechanical strength is an important characteristic of stems, which not only affects plant lodging, but also plays an important role in stem bend or break. In this paper, the mechanical strength, morphological indices and microstructure of P. lactiflora development inflorescence stems were measured and observed. The results showed that the mechanical strength of inflorescence stems gradually increased, and that the diameter of inflorescence stem was a direct indicator in estimating mechanical strength. Simultaneously, with the development of inflorescence stem, the number of vascular bundles increased, the vascular bundle was arranged more densely, the sclerenchyma cell wall thickened, and the proportion of vascular bundle and pith also increased. On this basis, cellulose and lignin contents were determined, PlCesA3, PlCesA6 and PlCCoAOMT were isolated and their expression patterns were examined including PlPAL. The results showed that cellulose was not strictly correlated with the mechanical strength of inflorescence stem, and lignin had a significant impact on it. In addition, PlCesA3 and PlCesA6 were not key members in cellulose synthesis of P. lactiflora and their functions were also different, but PlPAL and PlCCoAOMT regulated the lignin synthesis of P. lactiflora. These data indicated that PlPAL and PlCCoAOMT could be applied to improve the mechanical strength of P. lactiflora inflorescence stem in genetic engineering. PMID:22606025

Effects of inflorescence stem structure and cell wall components on the mechanical strength of inflorescence stem in herbaceous peony.

PubMed

Zhao, Daqiu; Han, Chenxia; Tao, Jun; Wang, Jing; Hao, Zhaojun; Geng, Qingping; Du, Bei

2012-01-01

Herbaceous peony (Paeonia lactiflora Pall.) is a traditional famous flower, but its poor inflorescence stem quality seriously constrains the development of the cut flower. Mechanical strength is an important characteristic of stems, which not only affects plant lodging, but also plays an important role in stem bend or break. In this paper, the mechanical strength, morphological indices and microstructure of P. lactiflora development inflorescence stems were measured and observed. The results showed that the mechanical strength of inflorescence stems gradually increased, and that the diameter of inflorescence stem was a direct indicator in estimating mechanical strength. Simultaneously, with the development of inflorescence stem, the number of vascular bundles increased, the vascular bundle was arranged more densely, the sclerenchyma cell wall thickened, and the proportion of vascular bundle and pith also increased. On this basis, cellulose and lignin contents were determined, PlCesA3, PlCesA6 and PlCCoAOMT were isolated and their expression patterns were examined including PlPAL. The results showed that cellulose was not strictly correlated with the mechanical strength of inflorescence stem, and lignin had a significant impact on it. In addition, PlCesA3 and PlCesA6 were not key members in cellulose synthesis of P. lactiflora and their functions were also different, but PlPAL and PlCCoAOMT regulated the lignin synthesis of P. lactiflora. These data indicated that PlPAL and PlCCoAOMT could be applied to improve the mechanical strength of P. lactiflora inflorescence stem in genetic engineering.

Variations the diameter tip of electrode on the resistance spot welding using electrode Cu on worksheet Fe

NASA Astrophysics Data System (ADS)

Baskoro, A. S.; Sugeng, S.; Sifa, Agus; Badruzzaman; Endramawan, Tito

2018-04-01

Resistance Spot Weld (RSW) is a welding technology which plays an important role that is often used in industry in large manufacturing industries, especially in the automotive sector, some of the parameters are affecting the welding process that give impact in the weld quality, diameter tip important impact on the resistance spot welding, This study can be categorized as experimental study by using Electrode material such as Cu and Fe Worksheet Materials, with a material thickness of 1 mm,0,8 mm, and 0,6 mm on each worksheet, and the large diameter of tip electrode (5√t) depend on the thickness of worksheet. Testing the material in the electrode and the worksheet by testing the composition and tensile test, and the hardness of the material used are to know the material used certainly. The result of the welding process was done by using the parameters voltage of 8KV, with a duty cycle of 50% using a variation of the time 8s-10s, and variations the electrode tip diameter that are affected by the thickness of the worksheet 5\\sqrt{t}, plate thickness used 1 mm, 0,8 mm and 0,6 mm, so that the electrodes was used to a thickness of 1 mm diameter tip electrode 5 mm, thickness 0,8 mm with an electrode tip diameter 4,5 mm and a thickness 0,6 mm with an electrode diameter of 4 mm, with current welding parameter 8kVA, and variations in holding time 10s, 9s and 8s 50% duty cycle, then testing welds with the standard shear test refers ASTM A370-2012 with more results to a thickness of 0,6 has the ability to withstand greater load on the holding time 8s and 9s, 10s, to a thickness 0,8 mm and 1 mm shear test results demonstrate the ability to withstand loads on the holding time of 10s and 9s have a greater ability than 8s on worksheet that has thickness 1 mm at a holding time of 10s, and then Maximum shear test averaging of 36,41 N at a worksheet with a thickness of 0,8 mm (diameter tip 4,5 mm) at a holding time of 8s and a mean minimum shear stress of 23,73 N at worksheet that has thickness 0,6 mm (diameter tip 4 mm).

Effects of phyllotaxy on biomechanical properties of stems of Cercis occidentalis (Fabaceae).

PubMed

Caringella, Marissa A; Bergman, Brett A; Stanfield, Ryan C; Ewers, Madeleine M; Bobich, Edward G; Ewers, Frank W

2014-01-01

Phyllotaxy, the arrangement of leaves on a stem, may impact the mechanical properties of woody stems several years after the leaves have been shed. We explored mechanical properties of a plant with alternate distichous phyllotaxy, with a row of leaves produced on each side of the stem, to determine whether the nodes behave as spring-like joints. Flexural stiffness of 1 cm diameter woody stems was measured in four directions with an Instron mechanical testing system; the xylem of the stems was then cut into node (former leaf junction) and nonnode segments for measurement of xylem density. Stems had 20% greater flexural stiffness in the plane perpendicular to the original leaf placement than in the parallel plane. The xylem in the node region was more flexible, but it had significantly greater tissue density than adjacent regions, contradicting the usual correlation between wood density and stiffness. Nodes can behave as spring-like joints in woody plants. For plagiotropic shoots, distichous phyllotaxy results in stems that resist up-and-down bending more than lateral back-and-forth movement. Thus, they may more effectively absorb applied loads from fruits, animals, wind, rain, and snow and resist stresses due to gravity without cracking and breaking. Under windy conditions, nodes may improve damping by absorbing vibrational energy and thus reducing oscillation damage. The effect of plant nodes also has biomimetic design implications for architects and material engineers.

Profile based image analysis for identification of chopped biomass stem nodes and internodes

USDA-ARS?s Scientific Manuscript database

Because of their significant variation in chemical composition, segregation of chopped biomass into nodes and internodes helps in efficient utilization of these feedstocks. Stem internodes having low ash content are a better feedstock for bioenergy and biofuel applications than nodes. However, separ...

Whole exome sequencing to estimate alloreactivity potential between donors and recipients in stem cell transplantation.

PubMed

Sampson, Juliana K; Sheth, Nihar U; Koparde, Vishal N; Scalora, Allison F; Serrano, Myrna G; Lee, Vladimir; Roberts, Catherine H; Jameson-Lee, Max; Ferreira-Gonzalez, Andrea; Manjili, Masoud H; Buck, Gregory A; Neale, Michael C; Toor, Amir A

2014-08-01

Whole exome sequencing (WES) was performed on stem cell transplant donor-recipient (D-R) pairs to determine the extent of potential antigenic variation at a molecular level. In a small cohort of D-R pairs, a high frequency of sequence variation was observed between the donor and recipient exomes independent of human leucocyte antigen (HLA) matching. Nonsynonymous, nonconservative single nucleotide polymorphisms were approximately twice as frequent in HLA-matched unrelated, compared with related D-R pairs. When mapped to individual chromosomes, these polymorphic nucleotides were uniformly distributed across the entire exome. In conclusion, WES reveals extensive nucleotide sequence variation in the exomes of HLA-matched donors and recipients. © 2014 John Wiley & Sons Ltd.

Concave Pit-Containing Scaffold Surfaces Improve Stem Cell-Derived Osteoblast Performance and Lead to Significant Bone Tissue Formation

PubMed Central

Cusella-De Angelis, Maria Gabriella; Laino, Gregorio; Piattelli, Adriano; Pacifici, Maurizio; De Rosa, Alfredo; Papaccio, Gianpaolo

2007-01-01

Background Scaffold surface features are thought to be important regulators of stem cell performance and endurance in tissue engineering applications, but details about these fundamental aspects of stem cell biology remain largely unclear. Methodology and Findings In the present study, smooth clinical-grade lactide-coglyolic acid 85:15 (PLGA) scaffolds were carved as membranes and treated with NMP (N-metil-pyrrolidone) to create controlled subtractive pits or microcavities. Scanning electron and confocal microscopy revealed that the NMP-treated membranes contained: (i) large microcavities of 80–120 µm in diameter and 40–100 µm in depth, which we termed primary; and (ii) smaller microcavities of 10–20 µm in diameter and 3–10 µm in depth located within the primary cavities, which we termed secondary. We asked whether a microcavity-rich scaffold had distinct bone-forming capabilities compared to a smooth one. To do so, mesenchymal stem cells derived from human dental pulp were seeded onto the two types of scaffold and monitored over time for cytoarchitectural characteristics, differentiation status and production of important factors, including bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF). We found that the microcavity-rich scaffold enhanced cell adhesion: the cells created intimate contact with secondary microcavities and were polarized. These cytological responses were not seen with the smooth-surface scaffold. Moreover, cells on the microcavity-rich scaffold released larger amounts of BMP-2 and VEGF into the culture medium and expressed higher alkaline phosphatase activity. When this type of scaffold was transplanted into rats, superior bone formation was elicited compared to cells seeded on the smooth scaffold. Conclusion In conclusion, surface microcavities appear to support a more vigorous osteogenic response of stem cells and should be used in the design of therapeutic substrates to improve bone repair and bioengineering applications in the future. PMID:17551577

A model of heat transfer in sapwood and implications for sap flux density measurements using thermal dissipation probes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wullschleger, Stan D; Childs, Kenneth W; King, Anthony Wayne

2011-01-01

A variety of thermal approaches are used to estimate sap flux density in stems of woody plants. Models have proven valuable tools for interpreting the behavior of heat pulse, heat balance, and heat field deformation techniques, but have seldom been used to describe heat transfer dynamics for the heat dissipation method. Therefore, to better understand the behavior of heat dissipation probes, a model was developed that takes into account the thermal properties of wood, the physical dimensions and thermal characteristics of the probes, and the conductive and convective heat transfer that occurs due to water flow in the sapwood. Probesmore » were simulated as aluminum tubes 20 mm in length and 2 mm in diameter, whereas sapwood, heartwood, and bark each had a density and water fraction that determined their thermal properties. Base simulations assumed a constant sap flux density with sapwood depth and no wounding or physical disruption of xylem beyond the 2 mm diameter hole drilled for probe installation. Simulations across a range of sap flux densities showed that the dimensionless quantity k defined as ( Tm T)/ T where Tm is the temperature differential ( T) between the heated and unheated probe under zero flow conditions was dependent on the thermal conductivity of the sapwood. The relationship between sap flux density and k was also sensitive to radial gradients in sap flux density and to xylem disruption near the probe. Monte Carlo analysis in which 1000 simulations were conducted while simultaneously varying thermal conductivity and wound diameter revealed that sap flux density and k showed considerable departure from the original calibration equation used with this technique. The departure was greatest for abrupt patterns of radial variation typical of ring-porous species. Depending on the specific combination of thermal conductivity and wound diameter, use of the original calibration equation resulted in an 81% under- to 48% over-estimation of sap flux density at modest flux rates. Future studies should verify these simulations and assess their utility in estimating sap flux density for this widely used technique.« less

A numerical study of zone-melting process for the thermoelectric material of Bi2Te3

NASA Astrophysics Data System (ADS)

Chen, W. C.; Wu, Y. C.; Hwang, W. S.; Hsieh, H. L.; Huang, J. Y.; Huang, T. K.

2015-06-01

In this study, a numerical model has been established by employing a commercial software; ProCAST, to simulate the variation/distribution of temperature and the subsequent microstructure of Bi2Te3 fabricated by zone-melting technique. Then an experiment is conducted to measure the temperature variation/distribution during the zone-melting process to validate the numerical system. Also, the effects of processing parameters on crystallization microstructure such as moving speed and temperature of heater are numerically evaluated. In the experiment, the Bi2Te3 powder are filled into a 30mm diameter quartz cylinder and the heater is set to 800°C with a moving speed 12.5 mm/hr. A thermocouple is inserted in the Bi2Te3 powder to measure the temperature variation/distribution of the zone-melting process. The temperature variation/distribution measured by experiment is compared to the results of numerical simulation. The results show that our model and the experiment are well matched. Then the model is used to evaluate the crystal formation for Bi2Te3 with a 30mm diameter process. It's found that when the moving speed is slower than 17.5 mm/hr, columnar crystal is obtained. In the end, we use this model to predict the crystal formation of zone-melting process for Bi2Te3 with a 45 mm diameter. The results show that it is difficult to grow columnar crystal when the diameter comes to 45mm.

Silk fibroin scaffolds with inverse opal structure for bone tissue engineering

PubMed Central

Sommer, Marianne R.; Vetsch, Jolanda R.; Leemann, Jessica; Müller, Ralph

2016-01-01

Abstract How scaffold porosity, pore diameter and geometry influence cellular behavior is‐although heavily researched ‐ merely understood, especially in 3D. This is mainly caused by a lack of suitable, reproducible scaffold fabrication methods, with processes such as gas foaming, lyophilization or particulate leaching still being the standard. Here we propose a method to generate highly porous silk fibroin scaffolds with monodisperse spherical pores, namely inverse opals, and study their effect on cell behavior. These silk fibroin inverse opal scaffolds were compared to salt‐leached silk fibroin scaffolds in terms of human mesenchymal stem cell response upon osteogenic differentiation signals. While cell number remained similar on both scaffold types, extracellular matrix mineralization nearly doubled on the newly developed scaffolds, suggesting a positive effect on cell differentiation. By using the very same material with comparable average pore diameters, this increase in mineral content can be attributed to either the differences in pore diameter distribution or the pore geometry. Although the exact mechanisms leading to enhanced mineralization in inverse opals are not yet fully understood, our results indicate that control over pore geometry alone can have a major impact on the bioactivity of a scaffold toward stem cell differentiation into bone tissue. © 2016 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2074–2084, 2017. PMID:27407014

Stability Analysis of a High Fibre Yield and Low Lignin Content “Thick Stem” Mutant in Tossa Jute (Corchorus olitorius L.)

PubMed Central

Mandal, Aninda; Datta, Animesh K.

2014-01-01

A “thick stem” mutant of Corchorus olitorius L. was induced at M2 (0.50%, 4 h, EMS) and the true breeding mutant is assessed across generations (M5 to M7) considering morphometric traits as well as SEM analysis of pollen grains and raw jute fibres, stem anatomy, cytogenetical attributes, and lignin content in relation to control. Furthermore, single fibre diameter and tensile strength are also analysed. The objective is to assess the stability of mutant for its effective exploration for raising a new plant type in tossa jute for commercial exploitation and efficient breeding. The mutant trait is monogenic recessive to normal. Results indicate that “thick stem” mutant is stable across generations (2n = 14) with distinctive high seed and fibre yield and significantly low lignin content. Stem anatomy of the mutant shows significant enhancement in fibre zone, number of fibre pyramids and fibre bundles per pyramid, and diameter of fibre cell in relation to control. Moreover, tensile strength of mutant fibre is significantly higher than control fibre and the trait is inversely related to fibre diameter. However the mutant is associated with low germination frequency, poor seed viability, and high pollen sterility, which may be eliminated through mutational approach followed by rigorous selection and efficient breeding. PMID:24860822

Variation in energy sorghum hybrid TX08001 biomass composition and lignin chemistry during development under irrigated and non-irrigated field conditions

PubMed Central

Olson, Sara N.; Ritter, Kimberley B.; Herb, Dustin W.; Karlen, Steven D.; Lu, Fachuang; Ralph, John; Rooney, William L.; Mullet, John E.

2018-01-01

This study was conducted to document the extent and basis of compositional variation of shoot biomass of the energy Sorghum bicolor hybrid TX08001 during development under field conditions. TX08001 is capable of accumulating ~40 Mg/ha of dry biomass under good growing conditions and this genotype allocates ~80% of its shoot biomass to stems. After 150 days of growth TX08001 stems had a fresh/dry weight ratio of ~3:1 and soluble biomass accounted for ~30% of stem biomass. A panel of diverse energy sorghum genotypes varied ~6-fold in the ratio of stem structural to soluble biomass after 150 days of growth. Near-infrared spectroscopic analysis (NIRS) showed that TX08001 leaves accumulated higher levels of protein, water extractives and ash compared to stems, which have higher sugar, cellulose, and lignin contents. TX08001 stem sucrose content varied during development, whereas the composition of TX08001 stem cell walls, which consisted of ~45–49% cellulose, ~27–30% xylan, and ~15–18% lignin, remained constant after 90 days post emergence until the end of the growing season (180 days). TX08001 and Della stem syringyl (S)/guaiacyl (G) (0.53–0.58) and ferulic acid (FA)/para-coumaric acid (pCA) ratios were similar whereas ratios of pCA/(S+G) differed between these genotypes. Additionally, an analysis of irrigated versus non-irrigated TX08001 revealed that non-irrigated hybrids exhibited a 50% reduction in total cell wall biomass, an ~2-fold increase in stem sugars, and an ~25% increase in water extractives relative to irrigated hybrids. This study provides a baseline of information to help guide further optimization of energy sorghum composition for various end-uses. PMID:29684037

A discrete element modelling approach for block impacts on trees

NASA Astrophysics Data System (ADS)

Toe, David; Bourrier, Franck; Olmedo, Ignatio; Berger, Frederic

2015-04-01

These past few year rockfall models explicitly accounting for block shape, especially those using the Discrete Element Method (DEM), have shown a good ability to predict rockfall trajectories. Integrating forest effects into those models still remain challenging. This study aims at using a DEM approach to model impacts of blocks on trees and identify the key parameters controlling the block kinematics after the impact on a tree. A DEM impact model of a block on a tree was developed and validated using laboratory experiments. Then, key parameters were assessed using a global sensitivity analyse. Modelling the impact of a block on a tree using DEM allows taking into account large displacements, material non-linearities and contacts between the block and the tree. Tree stems are represented by flexible cylinders model as plastic beams sustaining normal, shearing, bending, and twisting loading. Root soil interactions are modelled using a rotation stiffness acting on the bending moment at the bottom of the tree and a limit bending moment to account for tree overturning. The crown is taken into account using an additional mass distribute uniformly on the upper part of the tree. The block is represented by a sphere. The contact model between the block and the stem consists of an elastic frictional model. The DEM model was validated using laboratory impact tests carried out on 41 fresh beech (Fagus Sylvatica) stems. Each stem was 1,3 m long with a diameter between 3 to 7 cm. Wood stems were clamped on a rigid structure and impacted by a 149 kg charpy pendulum. Finally an intensive simulation campaign of blocks impacting trees was done to identify the input parameters controlling the block kinematics after the impact on a tree. 20 input parameters were considered in the DEM simulation model : 12 parameters were related to the tree and 8 parameters to the block. The results highlight that the impact velocity, the stem diameter, and the block volume are the three input parameters that control the block kinematics after impact.

Analysis of phytochemical variations in dioecious Tinospora cordifolia stems using HPLC/QTOF MS/MS and UPLC/QqQLIT -MS/MS.

PubMed

Bajpai, Vikas; Singh, Awantika; Chandra, Preeti; Negi, M P S; Kumar, Nikhil; Kumar, Brijesh

2016-01-01

The stem of dioecious Tinospora cordifolia (Menispermaceae) is a commonly used traditional Ayurvedic medicine in India having several therapeutic properties. To develop and validate LC-MS methods for the identification and simultaneous quantitation of various secondary metabolites and to study metabolomic variations in the stem of male and female plants. Ethanolic extract of stems were analysed by HPLC/ESI-QTOF-MS/MS for rapid screening of bioactive phytochemicals. High resolution MS and MS/MS in positive ESI mode were used for structural investigation of secondary metabolites. An UPLC/ESI-QqQ(LIT) -MS/MS method in MRM mode was developed and validated for the simultaneous quantitation of five bioactive alkaloids. Identification and characterisation of 36 metabolites including alkaloids, sesquiterpenes and phytoecdysteroids were performed using LC-MS and MS/MS techniques. The bioactive alkaloids such as jatrorrhizine, magnoflorine, isocorydine, palmatine and tetrahydropalmatine were successfully quantified in male and female plants. The mean abundances of magnoflorine jatrorrhizine, and oblongine were significantly (P < 0.05) higher in male plants while mean abundances of tetrahydropalmatine, norcoclaurine, and reticuline were significantly (P < 0.05) higher in female plants. Phytochemicals in the stem of male and female Tinospora cordifolia showed significant qualitative and quantitative variations. LC-MS and MS/MS methods can be used to differentiate between male and female plants based on their chemical profiles and quantities of the marker bioactive alkaloids. This chemical composition difference was also evident during vegetative stage when there were no male and female flowers. Copyright © 2015 John Wiley & Sons, Ltd.

Nanofabrication by advanced electron microscopy using intense and focused beam∗.

PubMed

Furuya, Kazuo

2008-01-01

The nanogrowth and nanofabrication of solid substances using an intense and focused electron beam are reviewed in terms of the application of scanning and transmission electron microscopy (SEM, TEM and STEM) to control the size, position and structure of nanomaterials. The first example discussed is the growth of freestanding nanotrees on insulator substrates by TEM. The growth process of the nanotrees was observed in situ and analyzed by high-resolution TEM (HRTEM) and was mainly controlled by the intensity of the electron beam. The second example is position- and size-controlled nanofabrication by STEM using a focused electron beam. The diameters of the nanostructures grown ranged from 4 to 20 nm depending on the size of the electron beam. Magnetic nanostructures were also obtained using an iron-containing precursor gas, Fe(CO) 5 . The freestanding iron nanoantennas were examined by electron holography. The magnetic field was observed to leak from the nanostructure body which appeared to act as a 'nanomagnet'. The third example described is the effect of a vacuum on the size and growth process of fabricated nanodots containing W in an ultrahigh-vacuum field-emission TEM (UHV-FE-TEM). The size of the dots can be controlled by changing the dose of electrons and the partial pressure of the precursor. The smallest particle size obtained was about 1.5 nm in diameter, which is the smallest size reported using this method. Finally, the importance of a smaller probe and a higher electron-beam current with atomic resolution is emphasized and an attempt to develop an ultrahigh-vacuum spherical aberration corrected STEM (Cs-corrected STEM) at NIMS is reported.

Nanofabrication by advanced electron microscopy using intense and focused beam∗

PubMed Central

Furuya, Kazuo

2008-01-01

The nanogrowth and nanofabrication of solid substances using an intense and focused electron beam are reviewed in terms of the application of scanning and transmission electron microscopy (SEM, TEM and STEM) to control the size, position and structure of nanomaterials. The first example discussed is the growth of freestanding nanotrees on insulator substrates by TEM. The growth process of the nanotrees was observed in situ and analyzed by high-resolution TEM (HRTEM) and was mainly controlled by the intensity of the electron beam. The second example is position- and size-controlled nanofabrication by STEM using a focused electron beam. The diameters of the nanostructures grown ranged from 4 to 20 nm depending on the size of the electron beam. Magnetic nanostructures were also obtained using an iron-containing precursor gas, Fe(CO)5. The freestanding iron nanoantennas were examined by electron holography. The magnetic field was observed to leak from the nanostructure body which appeared to act as a ‘nanomagnet’. The third example described is the effect of a vacuum on the size and growth process of fabricated nanodots containing W in an ultrahigh-vacuum field-emission TEM (UHV-FE-TEM). The size of the dots can be controlled by changing the dose of electrons and the partial pressure of the precursor. The smallest particle size obtained was about 1.5 nm in diameter, which is the smallest size reported using this method. Finally, the importance of a smaller probe and a higher electron-beam current with atomic resolution is emphasized and an attempt to develop an ultrahigh-vacuum spherical aberration corrected STEM (Cs-corrected STEM) at NIMS is reported. PMID:27877936

Efficacy of Systemic Insecticides for Control of the Invasive Goldspotted Oak Borer (Coleoptera: Buprestidae) in California.

PubMed

Coleman, Tom W; Smith, Sheri L; Jones, Michael I; Graves, Andrew D; Strom, Brian L

2017-10-01

From 2009 to 2013, we tested four systemic insecticide formulations and five application methods against the invasive goldspotted oak borer, Agrilus auroguttatus Schaeffer (Coleoptera: Buprestidae), in California. The insecticides were evaluated in three experiments: 1) 2009 remedial applications of emamectin benzoate (stem-injection) and imidacloprid (stem-injection and soil-injection); 2) 2009-2012 emamectin benzoate and imidacloprid initially applied at different times during the dormant season with varying injection technologies; and 3) 2013 dinotefuran applied to several tree diameter size classes. Adult leaf-feeding bioassays were used to assess the impact of systemic treatments against A. auroguttatus, whereas enzyme-linked immunosorbent assays determined the quantity of the active ingredient of insecticide residues in foliage. Imidacloprid (experiment 1) persisted at elevated levels in foliage of coast live oak, Quercus agrifolia Née, for 1.5 yr following stem injections. Stem injections of emamectin benzoate (experiment 2) sometimes significantly decreased survival in adults fed foliage from treated Q. agrifolia, and both the emamectin benzoate and imidacloprid treatments reduced adult feeding in some trials. Imidacloprid residues in Q. agrifolia and California black oak, Quercus kelloggii Newb., foliage remained at elevated levels (>10 µg/g) ∼2 yr postapplication. In 2013 (experiment 3), dinotefuran residues were highest in foliage collections 2 wk postapplication and greatest in smaller diameter oaks, but insecticide treatment had no effect on survival or frass production by adults fed foliage from treated trees. Systemic injections of emamectin benzoate and imidacloprid applied during the dormant season to uninfested or lightly infested oaks can reduce adult A. auroguttatus survival and maturation feeding. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Characterization of Seasonally Dependent Emergent Vegetation Variables for Coastal Impact Models

NASA Astrophysics Data System (ADS)

Stellern, C.; Grossman, E.; Linneman, S. R.; Fuller, R.

2015-12-01

Emergent wetland vegetation has been shown to mitigate coastal inundation and erosion hazards by reducing wave energy through friction (Shepard et al., 2011), although its use in coastal protection planning is limited because predictive models require improved vegetation data. We isolated biophysical characteristics (biomass, stem density, rigidity, etc.) of plants using horizontal digital photographs (Side-On Photos) in conjunction with remote sensing and physical surveys. We studied the dominant salt-marsh species/assemblages in Port Susan Bay of Washington State, a vulnerable estuary that has experienced up to 1 kilometer of marsh retreat since the mid-1960s. We measured plant height, stem diameter, stem density (area available for flow) from fall to early spring (August 2014 through April 2015) using Side-On Photography and digital image processing techniques. Metrics from Side-On Photography were highly correlated to physical lab measurements. Vegetation rigidity was measured in-situ with a handheld digital scale with respect to measurement height and bending angle. Plant elasticity showed a strong correlation to stem diameter in two dominant bulrush species. We employed remote sensing supervised classifications techniques (Maximum-Likelihood and Decision Tree Classifiers) to hyperspectral imagery to map the spatial extent of vegetation assemblages with an overall accuracy of 86.7%. Combining these methods enabled us to extrapolate and validate vegetation characteristics across the study area and to estimate species-specific friction coefficients for input to cross-shore wave models. On-going studies include sensitivity analyses of wave models to seasonally-dependent vegetation parameters in the nearshore and ultimately wave impacts along the coast. By accounting for site-specific and spatiotemporal variability in vegetation data, we inform scientific understanding of the interactions of vegetation, waves, and sediment processes.

Selection and phenotypic characterization of a core collection of Brachypodium distachyon inbred lines.

PubMed

Tyler, Ludmila; Fangel, Jonatan U; Fagerström, Alexandra Dotson; Steinwand, Michael A; Raab, Theodore K; Willats, William Gt; Vogel, John P

2014-01-14

The model grass Brachypodium distachyon is increasingly used to study various aspects of grass biology. A large and genotypically diverse collection of B. distachyon germplasm has been assembled by the research community. The natural variation in this collection can serve as a powerful experimental tool for many areas of inquiry, including investigating biomass traits. We surveyed the phenotypic diversity in a large collection of inbred lines and then selected a core collection of lines for more detailed analysis with an emphasis on traits relevant to the use of grasses as biofuel and grain crops. Phenotypic characters examined included plant height, growth habit, stem density, flowering time, and seed weight. We also surveyed differences in cell wall composition using near infrared spectroscopy (NIR) and comprehensive microarray polymer profiling (CoMPP). In all cases, we observed extensive natural variation including a two-fold variation in stem density, four-fold variation in ferulic acid bound to hemicellulose, and 1.7-fold variation in seed mass. These characterizations can provide the criteria for selecting diverse lines for future investigations of the genetic basis of the observed phenotypic variation.

Genetic analysis of QTL for eye cross and eye diameter in common carp (Cyprinus carpio L.) using microsatellites and SNPs.

PubMed

Jin, S B; Zhang, X F; Lu, J G; Fu, H T; Jia, Z Y; Sun, X W

2015-04-17

A group of 107 F1 hybrid common carp was used to construct a linkage map using JoinMap 4.0. A total of 4877 microsatellite and single nucleotide polymorphism (SNP) markers isolated from a genomic library (978 microsatellite and 3899 SNP markers) were assigned to construct the genetic map, which comprised 50 linkage groups. The total length of the linkage map for the common carp was 4775.90 cM with an average distance between markers of 0.98 cM. Ten quantitative trait loci (QTL) were associated with eye diameter, corresponding to 10.5-57.2% of the total phenotypic variation. Twenty QTL were related to eye cross, contributing to 10.8-36.9% of the total phenotypic variation. Two QTL for eye diameter and four QTL for eye cross each accounted for more than 20% of the total phenotypic variation and were considered to be major QTL. One growth factor related to eye diameter was observed on LG10 of the common carp genome, and three growth factors related to eye cross were observed on LG10, LG35, and LG44 of the common carp genome. The significant positive relationship of eye cross and eye diameter with other commercial traits suggests that eye diameter and eye cross can be used to assist in indirect selection for many commercial traits, particularly body weight. Thus, the growth factor for eye cross may also contribute to the growth of body weight, implying that aggregate breeding could have multiple effects. These findings provide information for future genetic studies and breeding of common carp.

Effect of sex and rearing system on the quality and mineral content of fiber from raeini cashmere goats

PubMed Central

2012-01-01

The aim of this study was to compare the quality characteristics and mineral content of the fiber from male and female cashmere goats raised under different management systems. Male and female Raeini cashmere goats (<1.5 years of age, n = 48) were selected from flocks raised at a government breeding station or raised commercially under either rural or nomadic conditions. The staple length, cashmere fiber diameter, coefficient of variation for fiber diameter, percentage of cashmere in a fleece, percentage of guard hair in a fleece and cashmere tenacity averaged 4.6 ±0.1 cm, 18.0 ±0.1 μm, 20.9 ± 0.4%, 66.1 ± 1.5%, 33.8 ± 1.5% and 1.8 ± 0.2 gf/tex, respectively. The sulfur, copper and zinc content of the cashmere averaged 2.8 ± 0.1%, 0.00065 ± 0.00002% and 0.01276 ± 0.00025%, respectively. Rearing method significantly affected staple length, coefficient of variation of fiber diameter, cashmere tenacity and copper content. Males had a higher coefficient of variation of fiber diameter and cashmere tenacity than females (P < 0.05). PMID:22958733

Stemflow: A literature review and the challenges ahead

NASA Astrophysics Data System (ADS)

José, Návar

2013-04-01

Stemflow is the rainfall portion that flows down to the ground via trunks or stems. It is a localized point source input of precipitation and solutes at the stem base, creating islands of soil moisture and fertility. It accounts on average for less than 5% of the gross rainfall but maximum figures can reach 3.5%, 11.3%, and 19% in tropical, temperate and semi-arid plant communities, respectively. However, recent research has shown these statistics could be twice as large in overstocked semi-arid, subtropical and temperate forest stands. Tree and shrub species funnel different stemflow depths and canopy features; diameter at breast height, top height, canopy area and volume, branch number and position; bark smoothness, etc. are the most frequent independent variables employed to explain the large intrinsic variation. The funneling ratio evaluates the hydro-pedological importance; calculated by the division of stemflow volume by the stem base area and by the rainfall depth. Statistics quite often show funneling ratios >> 1. Assessments of the stemflow infiltration area quite frequently show the islands of soil moisture are at least twice as large as the soil depth wetted by rainfall in the open and calculations are in agreement with several visual observations. Empirical evaluations quite often also show the potential contribution of stemflow to groundwater recharge and streamflow generation. However, assessments of the infiltration area and depth quite frequently deviate from visual observations conducted by dying pathways, showing roots are the most frequent sources of stemflow transport within soils. Should this be the case for most trees, then the number of roots and their position within the soil profile would help to better forecast the stemflow (rootflow) infiltration depth and the potential triggering of other hydrological processes. Current mathematical approaches challenge future research on stemflow and rootflow to better understand the hydro-eco-pedological importance of point source inputs of plant communities.

Selecting superior yellow birch trees; a preliminary guide.

Treesearch

Knud E. Clausen; Richard M. Godman

1967-01-01

Describes procedures to follow and characteristics to consider in selecting superior yellow birch trees. The first selection should be on the basis of tree quality. Characteristics to consider are as follows: for the stem--straightness, roundness, taper grain, self-pruning, and absence of defects; for the crown--apical dominance, branch angle, and branch diameter;...

Taper equation and volume tables for plantation-grown red alder.

Treesearch

Andrew A. Bluhm; Sean M. Garber; David E. Hibbs

2007-01-01

A taper equation and associated tables are presented for red alder (Alnus rubra Bong.) trees grown in plantations. The data were gathered from variable-density experimental plantations throughout the Pacific Northwest. Diameter inside bark along the stem was fitted to a variable exponent model form by using generalized nonlinear least squares and a...

Leaf, woody, and root biomass of Populus irrigated with landfill leachate

Treesearch

Jill A. Zalesny; Ronald S., Jr. Zalesny; D.R. Coyle; R.B. Hall

2007-01-01

Poplar (Populus spp.) trees can be utilized for ecological leachate disposal when applied as an irrigation source for managed tree systems. Our objective was to evaluate differences in tree height, diameter, volume, and biomass of leaf, stem, branch, and root tissues of Populus trees after two seasons of irrigation with municipal...

Forest Stand Canopy Structure Attribute Estimation from High Resolution Digital Airborne Imagery

Treesearch

Demetrios Gatziolis

2006-01-01

A study of forest stand canopy variable assessment using digital, airborne, multispectral imagery is presented. Variable estimation involves stem density, canopy closure, and mean crown diameter, and it is based on quantification of spatial autocorrelation among pixel digital numbers (DN) using variogram analysis and an alternative, non-parametric approach known as...

A review of past research on dendrometers

Treesearch

Neil Clark; Randolph H. Wynne; Daniel L. Schmoldt

2000-01-01

The purpose of a dendrometer is to measure tree diameter. Contact and noncontact dendrometers accomplish this task by collecting different metrics, including girth or distance between tangent points on a tree stem. Many dendrometers have been developed in the last quarter century and many have been retired. This article summarizes instrument developments and...

Whitebark pine diameter growth response to removal of competition

Treesearch

Robert E. Keane; Kathy L. Gray; Laura J. Dickinson

2007-01-01

Silvicultural cutting treatments may be needed to restore whitebark pine (Pinus albicaulis) forests, but little is known of the response of this species to removal of competition through prescribed burning or silvicultural cuttings. We analyzed stem cross-sections from 48 whitebark pine trees in Montana around which most of the competing vegetation...

30 CFR 816.68 - Use of explosives: Records of blasting operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (f) Type of material blasted. (g) Sketches of the blast pattern including number of holes, burden, spacing, decks, and delay pattern. (h) Diameter and depth of holes. (i) Types of explosives used. (j...-millisecond period. (l) Initiation system. (m) Type and length of stemming. (n) Mats or other protections used...