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

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

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...

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 51.320 - 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...

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.

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.

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.

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....

Numerical Modeling of Surface and Volumetric Cooling using Optimal T- and Y-shaped Flow Channels

NASA Astrophysics Data System (ADS)

Kosaraju, Srinivas

2017-11-01

The layout of T- and V-shaped flow channel networks on a surface can be optimized for minimum pressure drop and pumping power. The results of the optimization are in the form of geometric parameters such as length and diameter ratios of the stem and branch sections. While these flow channels are optimized for minimum pressure drop, they can also be used for surface and volumetric cooling applications such as heat exchangers, air conditioning and electronics cooling. In this paper, an effort has been made to study the heat transfer characteristics of multiple T- and Y-shaped flow channel configurations using numerical simulations. All configurations are subjected to same input parameters and heat generation constraints. Comparisons are made with similar results published in literature.

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...

Tree-stem diameter fluctuates with the lunar tides and perhaps with geomagnetic activity.

PubMed

Barlow, Peter W; Mikulecký, Miroslav; Střeštík, Jaroslav

2010-11-01

Our initial objective has been to examine the suggestion of Zürcher et al. (Nature 392:665–666, 1998) that the naturally occurring variations in stem diameter of two experimental trees of Picea alba were related to near simultaneous variations in the lunisolar tidal acceleration. The relationship was positive: Lunar peaks were roughly synchronous with stem diameter peaks. To extend the investigation of this putative relationship, additional data on stem diameter variations from six other tree species were gathered from published literature. Sixteen sets of data were analysed retrospectively using graphical representations as well as cosinor analysis, statistical cross-correlation and cross-spectral analysis, together with estimated values of the lunisolar tidal acceleration corresponding to the sites, dates and times of collection of the biological data. Positive relationships were revealed between the daily variations of stem diameter and the variations of the lunisolar tidal acceleration. Although this relationship could be mediated by a 24.8-h lunar rhythm, the presence of a solar rhythm of 24.0 h could not be ruled out. Studies of transpiration in two of the observed trees indicated that although this variable was not linked to stem diameter variation, it might also be subject to lunisolar gravitational regulation. In three cases, the geomagnetic Thule index showed a weak but reciprocal relationship with stem diameter variation, as well as a positive relationship with the lunisolar tidal force. In conclusion, it seems that lunar gravity alone could influence stem diameter variation and that, under certain circumstances, additional regulation may come from the geomagnetic flux.

Understanding the effect of carbon status on stem diameter variations

PubMed Central

De Swaef, Tom; Driever, Steven M.; Van Meulebroek, Lieven; Vanhaecke, Lynn; Marcelis, Leo F. M.; Steppe, Kathy

2013-01-01

Background Carbon assimilation and leaf-to-fruit sugar transport are, along with plant water status, the driving mechanisms for fruit growth. An integrated comprehension of the plant water and carbon relationships is therefore essential to better understand water and dry matter accumulation. Variations in stem diameter result from an integrated response to plant water and carbon status and are as such a valuable source of information. Methods A mechanistic water flow and storage model was used to relate variations in stem diameter to phloem sugar loading and sugar concentration dynamics in tomato. The simulation results were compared with an independent model, simulating phloem sucrose loading at the leaf level based on photosynthesis and sugar metabolism kinetics and enabled a mechanistic interpretation of the ‘one common assimilate pool’ concept for tomato. Key Results Combining stem diameter variation measurements and mechanistic modelling allowed us to distinguish instantaneous dynamics in the plant water relations and gradual variations in plant carbon status. Additionally, the model combined with stem diameter measurements enabled prediction of dynamic variables which are difficult to measure in a continuous and non-destructive way, such as xylem water potential and phloem hydrostatic potential. Finally, dynamics in phloem sugar loading and sugar concentration were distilled from stem diameter variations. Conclusions Stem diameter variations, when used in mechanistic models, have great potential to continuously monitor and interpret plant water and carbon relations under natural growing conditions. PMID:23186836

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.

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.

Substrate Curvature Restricts Spreading and Induces Differentiation of Human Mesenchymal Stem Cells.

PubMed

Lee, Sang Joo; Yang, Shengyuan

2017-09-01

While cells attach, spread, migrate, proliferate, and differentiate in three-dimensional (3D) micromechanical environments, the mechanical factors of these environments influence the shapes, sizes, and adhesion forces of the cells. Here, the authors culture human mesenchymal stem cells (hMSCs) on a unique class of curvature-defined substrates, micro glass ball embedded polyacrylamide gels, prepared with an improved protocol, and investigate the spreading responses of the hMSCs on the glass balls to study the effects of substrate curvature on the spreading of hMSCs. The authors find that, among the used diameters of glass balls, the minimum diameter of a glass ball on which an hMSC can attach and spread is 500 μm. In contrast to the well-spread morphologies with randomly-multiple lamellipodia for the hMSCs growing on the flat glass plates, the morphologies of the hMSCs growing on the glass balls are almost uniformly spindle-shaped with two lamellipodia. The sensitivities of the attachment and spreading morphology of an hMSC to substrate curvature are very different from those of a fibroblast. The RT-PCR analysis reveals that the substrate curvature alone can induce adipogenesis of the hMSCs. These findings imply that substrate curvature has profound effects on stem cell behaviors, and detailed and in-depth studies on these effects and their underlying biophysical mechanisms are necessary. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Modelling reveals endogenous osmotic adaptation of storage tissue water potential as an important driver determining different stem diameter variation patterns in the mangrove species Avicennia marina and Rhizophora stylosa.

PubMed

Vandegehuchte, Maurits W; Guyot, Adrien; Hubeau, Michiel; De Swaef, Tom; Lockington, David A; Steppe, Kathy

2014-09-01

Stem diameter variations are mainly determined by the radial water transport between xylem and storage tissues. This radial transport results from the water potential difference between these tissues, which is influenced by both hydraulic and carbon related processes. Measurements have shown that when subjected to the same environmental conditions, the co-occurring mangrove species Avicennia marina and Rhizophora stylosa unexpectedly show a totally different pattern in daily stem diameter variation. Using in situ measurements of stem diameter variation, stem water potential and sap flow, a mechanistic flow and storage model based on the cohesion-tension theory was applied to assess the differences in osmotic storage water potential between Avicennia marina and Rhizophora stylosa. Both species, subjected to the same environmental conditions, showed a resembling daily pattern in simulated osmotic storage water potential. However, the osmotic storage water potential of R. stylosa started to decrease slightly after that of A. marina in the morning and increased again slightly later in the evening. This small shift in osmotic storage water potential likely underlaid the marked differences in daily stem diameter variation pattern between the two species. The results show that in addition to environmental dynamics, endogenous changes in the osmotic storage water potential must be taken into account in order to accurately predict stem diameter variations, and hence 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.

A miniature ultrasonic actuator-control system for plant stem diameter micro-variation measurements

USDA-ARS?s Scientific Manuscript database

Measurements of micro-variations in plant stem diameter are potentially useful to optimize irrigation decision support systems that are based on plant physiological responses. However, for this technology to be suitable for field applications, problems associated with stem softness and micro variati...

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...

Relationships between stem diameter, sapwood area, leaf area and transpiration in a young mountain ash forest.

PubMed

Vertessy, R A; Benyon, R G; O'Sullivan, S K; Gribben, P R

1995-09-01

We examined relationships between stem diameter, sapwood area, leaf area and transpiration in a 15-year-old mountain ash (Eucalyptus regnans F. Muell.) forest containing silver wattle (Acacia dealbata Link.) as a suppressed overstory species and mountain hickory (Acacia frigescens J.H. Willis) as an understory species. Stem diameter explained 93% of the variation in leaf area, 96% of the variation in sapwood area and 88% of the variation in mean daily spring transpiration in 19 mountain ash trees. In seven silver wattle trees, stem diameter explained 87% of the variation in sapwood area but was a poor predictor of the other variables. When transpiration measurements from individual trees were scaled up to a plot basis, using stem diameter values for 164 mountain ash trees and 124 silver wattle trees, mean daily spring transpiration rates of the two species were 2.3 and 0.6 mm day(-1), respectively. The leaf area index of the plot was estimated directly by destructive sampling, and indirectly with an LAI-2000 plant canopy analyzer and by hemispherical canopy photography. All three methods gave similar results.

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.

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...

Feasibility of utilizing small diameter southern pine for biomass in the Virginia Coastal Plain

Treesearch

Nathan C. Hanzelka; M. Chad Bolding; Scott M. Barrett; Jay Sullivan

2016-01-01

New or retrofitted wood-fired energy plants have increased demand for woody biomass in the stateof Virginia. Loblolly pine (Pinus taeda) commonly serves as a feedstock for these energy plants. Pulpwood conventionally requires a minimum diameter of 4 inches diameter at breast height (DBH) for merchantability, whereas a minimum merchantable diameter...

7 CFR 51.311 - Marking requirements.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS) United States Standards for Grades of Apples Marking Requirements § 51.311 Marking requirements... minimum diameter of apples packed in a closed container shall be indicated on the container. For apple... varieties, the minimum diameter and minimum weight of apples packed in a closed container shall be indicated...

7 CFR 51.311 - Marking requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS) United States Standards for Grades of Apples Marking Requirements § 51.311 Marking requirements... minimum diameter of apples packed in a closed container shall be indicated on the container. For apple... varieties, the minimum diameter and minimum weight of apples packed in a closed container shall be indicated...

7 CFR 51.311 - Marking requirements.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS) United States Standards for Grades of Apples Marking Requirements § 51.311 Marking requirements... minimum diameter of apples packed in a closed container shall be indicated on the container. For apple... varieties, the minimum diameter and minimum weight of apples packed in a closed container shall be indicated...

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...

Freezing resistance in Patagonian woody shrubs: the role of cell wall elasticity and stem vessel size.

PubMed

Zhang, Yong-Jiang; Bucci, Sandra J; Arias, Nadia S; Scholz, Fabian G; Hao, Guang-You; Cao, Kun-Fang; Goldstein, Guillermo

2016-08-01

Freezing resistance through avoidance or tolerance of extracellular ice nucleation is important for plant survival in habitats with frequent subzero temperatures. However, the role of cell walls in leaf freezing resistance and the coordination between leaf and stem physiological processes under subzero temperatures are not well understood. We studied leaf and stem responses to freezing temperatures, leaf and stem supercooling, leaf bulk elastic modulus and stem xylem vessel size of six Patagonian shrub species from two sites (plateau and low elevation sites) with different elevation and minimum temperatures. Ice seeding was initiated in the stem and quickly spread to leaves, but two species from the plateau site had barriers against rapid spread of ice. Shrubs with xylem vessels smaller in diameter had greater stem supercooling capacity, i.e., ice nucleated at lower subzero temperatures. Only one species with the lowest ice nucleation temperature among all species studied exhibited freezing avoidance by substantial supercooling, while the rest were able to tolerate extracellular freezing from -11.3 to -20 °C. Leaves of species with more rigid cell walls (higher bulk elastic modulus) could survive freezing to lower subzero temperatures, suggesting that rigid cell walls potentially reduce the degree of physical injury to cell membranes during the extracellular freezing and/or thaw processes. In conclusion, our results reveal the temporal-spatial ice spreading pattern (from stem to leaves) in Patagonian shrubs, and indicate the role of xylem vessel size in determining supercooling capacity and the role of cell wall elasticity in determining leaf tolerance of extracellular ice formation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Ontogenetic changes in size, allometry, and mechanical design of tropical rain forest trees.

PubMed

Sterck, F; Bongers, F

1998-02-01

Size, allometry, and mechanical design were measured for trees of three canopy species in a tropical rain forest in French Guiana. Mechanical design was expressed as the safety factor, using the elastic-stability model, and the wind resistance factor, using the constant-stress model. Changes with ontogeny were described as regressions using stem diameter as the independent variable, and they were compared between species. Height, crown size, and the wind resistance factor increased with ontogeny. The safety factor decreased to a minimum and then increased continuously in thicker trees. The crown width/height ratio did not change with ontogeny. Interspecific differences in allometry and mechanical design were related to the adult stature of the species, and not to shade tolerance. The short stature species (Vouacapoua americana) was less slender (height:DBH [stem diameter at 1.3 m] ratio) and had a higher crown width/height ratio than the tall stature species (Goupia glabra and Dicorynia guianensis). Vouacapoua had a higher safety factor, but a similar wind resistance factor. The safety factors of our study species were lower than those of two temperate tree species because of a higher slenderness. Differences in safety factors between tropical and temperate trees may result from unrealistic assumptions of the elastic-stability model, and may also be related to lower light levels and-or wind rates in the tropics.

49 CFR 179.300-6 - Thickness of plates.

Code of Federal Regulations, 2010 CFR

2010-10-01

....037 Where: d = inside diameter in inches; E = 1.0 welded joint efficiency; P = minimum required bursting pressure in psig; S = minimum tensile strength of plate material in p.s.i. as prescribed in § 179... −d 2) where: d = inside diameter in inches; D = outside diameter in inches; p = tank test pressure in...

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.

Diameter-Constrained Steiner Tree

NASA Astrophysics Data System (ADS)

Ding, Wei; Lin, Guohui; Xue, Guoliang

Given an edge-weighted undirected graph G = (V,E,c,w), where each edge e ∈ E has a cost c(e) and a weight w(e), a set S ⊆ V of terminals and a positive constant D 0, we seek a minimum cost Steiner tree where all terminals appear as leaves and its diameter is bounded by D 0. Note that the diameter of a tree represents the maximum weight of path connecting two different leaves in the tree. Such problem is called the minimum cost diameter-constrained Steiner tree problem. This problem is NP-hard even when the topology of Steiner tree is fixed. In present paper we focus on this restricted version and present a fully polynomial time approximation scheme (FPTAS) for computing a minimum cost diameter-constrained Steiner tree under a fixed topology.

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.

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...

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.

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.

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.

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

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...

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,...

Adverse Reactions to Metal on Metal Are Not Exclusive to Large Heads in Total Hip Arthroplasty.

PubMed

Lombardi, Adolph V; Berend, Keith R; Adams, Joanne B; Satterwhite, Keri L

2016-02-01

There is some suggestion that smaller diameter heads in metal-on-metal total hip arthroplasty (MoM THA) may be less prone to the adverse reactions to metal debris (ARMD) seen with large-diameter heads. We reviewed our population of patients with small head (≤ 32 mm) MoM THA to determine (1) the frequency of ARMD; (2) potential risk factors for ARMD in this population; and (3) the etiology of revision and Kaplan-Meier survivorship with revision for all causes. Small-diameter head MoM devices were used in 9% (347 of 3753) of primary THAs during the study period (January 1996 to March 2005). We generally used these implants in younger, more active, higher-demand patients. Three hundred hips (258 patients) had MoM THA using a titanium modular acetabular component with a cobalt-chromium tapered insert and were available for review with minimum 2-year followup (mean, 10 years; range, 2-19 years). Complete followup was available in 86% of hips (300 of 347). Clinical records and radiographs were reviewed to determine the frequency and etiology of revision. Kaplan-Meier survivorship analysis was performed. ARMD frequency was 5% (14 of 300 hips) and represented 70% (14 of 20) of revisions performed. Using multivariate analysis, no variable tested, including height, weight, body mass index, age, cup diameter, cup angle, use of screws, stem diameter, stem type, head diameter, preoperative clinical score, diagnosis, activity level, or sex, was significant as a risk factor for revision. Twenty hips have been revised: two for infection, four for aseptic loosening, and 14 for ARMD. Kaplan-Meier analysis revealed survival free of component revision for all causes was 95% at 10 years (95% confidence interval [CI], 91%-97%), 92% at 15 years (95% CI, 87%-95%), and 72% at 19 years (95% CI, 43%-90%), and survival free of component revision for aseptic causes was 96% at 10 years (95% CI, 92%-98%), 92% at 15 years (95% CI, 88%-95%), and 73% at 19 years (95% CI, 43%-90%). The late onset and devastating nature of metal-related failures is concerning with this small-diameter MoM device. Although the liner is modular, it cannot be exchanged and full acetabular revision is required. Patients with all MoM THA devices should be encouraged to return for clinical and radiographic followup, and clinicians should maintain a low threshold to perform a systematic evaluation. Symptomatic patients should undergo thorough investigation and vigilant observation for ARMD. Level IV, therapeutic 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...

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.

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Methods of Sampling and Calculation... where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated on the basis of count. (b) In all other...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Methods of Sampling and Calculation... where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated on the basis of count. (b) In all other...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Methods of Sampling and Calculation... where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated on the basis of count. (b) In all other...

7 CFR 51.1995 - U.S. No. 1.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Well formed; and, (2) Clean and bright. (3) Free from: (i) Blanks; and, (ii) Broken or split shells. (4... minimum diameter, minimum and maximum diameters, or in accordance with one of the size classifications in Table I. Table I Size classifications Maximum size—Will pass through a round opening of the following...

16 CFR 1512.6 - Requirements for steering system.

Code of Federal Regulations, 2014 CFR

2014-01-01

... stem insertion mark. Quill-type handlebar stems 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...

16 CFR 1512.6 - Requirements for steering system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... stem insertion mark. Quill-type handlebar stems 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...

16 CFR § 1512.6 - Requirements for steering system.

Code of Federal Regulations, 2013 CFR

2013-01-01

... stem insertion mark. Quill-type handlebar stems 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...

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.

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.

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...

CFD-DEM modeling the effect of column size and bed height on minimum fluidization velocity in micro fluidized beds with Geldart B particles

DOE PAGES

Xu, Yupeng; Li, Tingwen; Musser, Jordan; ...

2017-06-07

The fluidization behavior of Geldart B particles in micro fluidized beds is investigated numerically using Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) available in the open-source Multiphase Flow with Interphase eXchanges (MFIX) code. The effects of different bed inner diameters (D) of 8 mm, 12 mm, 16 mm and various initial static bed heights (H) were examined. It is found that both decreasing the column diameter and increasing the bed height in a micro fluidized bed increases the minimum fluidization velocity (Umf). The observed overshoot in pressure drop that occurs before the onset of fluidization decreases in magnitudemore » with increasing column diameter, however there is less sensitivity to bed height. Overall, the numerical results agree qualitatively with existing theoretical correlations and experimental studies. The simulations show that both column diameter and particle-wall friction contribute to the variation in minimum fluidization velocity. Finally, these two factors are coupled and hard to separate. The detailed influences of wall friction on minimum fluidization velocity are then investigated for a prescribed column diameter of 8 mm by varying the wall friction from 0 to 0.4.« less

CFD-DEM modeling the effect of column size and bed height on minimum fluidization velocity in micro fluidized beds with Geldart B particles

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

Xu, Yupeng; Li, Tingwen; Musser, Jordan

The fluidization behavior of Geldart B particles in micro fluidized beds is investigated numerically using Computational Fluid Dynamics coupled with Discrete Element Method (CFD-DEM) available in the open-source Multiphase Flow with Interphase eXchanges (MFIX) code. The effects of different bed inner diameters (D) of 8 mm, 12 mm, 16 mm and various initial static bed heights (H) were examined. It is found that both decreasing the column diameter and increasing the bed height in a micro fluidized bed increases the minimum fluidization velocity (Umf). The observed overshoot in pressure drop that occurs before the onset of fluidization decreases in magnitudemore » with increasing column diameter, however there is less sensitivity to bed height. Overall, the numerical results agree qualitatively with existing theoretical correlations and experimental studies. The simulations show that both column diameter and particle-wall friction contribute to the variation in minimum fluidization velocity. Finally, these two factors are coupled and hard to separate. The detailed influences of wall friction on minimum fluidization velocity are then investigated for a prescribed column diameter of 8 mm by varying the wall friction from 0 to 0.4.« less

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...

Key node selection in minimum-cost control of complex networks

NASA Astrophysics Data System (ADS)

Ding, Jie; Wen, Changyun; Li, Guoqi

2017-11-01

Finding the key node set that is connected with a given number of external control sources for driving complex networks from initial state to any predefined state with minimum cost, known as minimum-cost control problem, is critically important but remains largely open. By defining an importance index for each node, we propose revisited projected gradient method extension (R-PGME) in Monte-Carlo scenario to determine key node set. It is found that the importance index of a node is strongly correlated to occurrence rate of that node to be selected as a key node in Monte-Carlo realizations for three elementary topologies, Erdős-Rényi and scale-free networks. We also discover the distribution patterns of key nodes when the control cost reaches its minimum. Specifically, the importance indices of all nodes in an elementary stem show a quasi-periodic distribution with high peak values in the beginning and end of a quasi-period while they approach to a uniform distribution in an elementary cycle. We further point out that an elementary dilation can be regarded as two elementary stems whose lengths are the closest, and the importance indices in each stem present similar distribution as in an elementary stem. Our results provide a better understanding and deep insight of locating the key nodes in different topologies with minimum control cost.

Tree stem diameter variations and transpiration in Scots pine: an analysis using a dynamic sap flow model.

PubMed

Perämäki, M; Nikinmaa, E; Sevanto, S; Ilvesniemi, H; Siivola, E; Hari, P; Vesala, T

2001-08-01

A dynamic model for simulating water flow in a Scots pine (Pinus sylvestris L.) tree was developed. The model is based on the cohesion theory and the assumption that fluctuating water tension driven by transpiration, together with the elasticity of wood tissue, causes variations in the diameter of a tree stem and branches. The change in xylem diameter can be linked to water tension in accordance with Hookeâ s law. The model was tested against field measurements of the diurnal xylem diameter change at different heights in a 37-year-old Scots pine at Hyytiälä, southern Finland (61 degrees 51' N, 24 degrees 17' E, 181 m a.s.l.). Shoot transpiration and soil water potential were input data for the model. The biomechanical and hydraulic properties of wood and fine root hydraulic conductance were estimated from simulated and measured stem diameter changes during the course of 1 day. The estimated parameters attained values similar to literature values. The ratios of estimated parameters to literature values ranged from 0.5 to 0.9. The model predictions (stem diameters at several heights) were in close agreement with the measurements for a period of 6 days. The time lag between changes in transpiration rate and in sap flow rate at the base of the tree was about half an hour. The analysis showed that 40% of the resistance between the soil and the top of the tree was located in the rhizosphere. Modeling the water tension gradient and consequent woody diameter changes offer a convenient means of studying the link between wood hydraulic conductivity and control of transpiration.

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...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and... weigh ten pounds or less, or in any container where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated...

7 CFR 51.308 - Methods of sampling and calculation of percentages.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and... weigh ten pounds or less, or in any container where the minimum diameter of the smallest apple does not vary more than 1/2 inch from the minimum diameter of the largest apple, percentages shall be calculated...

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.

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.

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.

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

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;...

Measuring Biomass and Carbon Stock in Resprouting Woody Plants

PubMed Central

Matula, Radim; Damborská, Lenka; Nečasová, Monika; Geršl, Milan; Šrámek, Martin

2015-01-01

Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation. PMID:25719601

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.

Determination of Shapes of Boattail Bodies of Revolution for Minimum Wave Drag

NASA Technical Reports Server (NTRS)

Adams, Mac C.

1951-01-01

By use of an approximate equation for the wave drag of slender bodies of revolution in a supersonic flow field, the optimum shapes of certain boattail bodies are determined for minimum wave drag. The properties of three specific families of bodies are determined, the first family consisting of bodies having a given length and base area and a contour passing through a prescribed point between the nose and base, the second family having fixed length, base area, and maximum area, and the third family having given length, volume, and base area. The method presented is easily generalized to determine minimum-wave-drag profile shapes which have contours that must pass through any prescribed number of points. According to linearized theory, the optimum profiles are found to have infinite slope at the nose but zero radius of curvature so that the bodies appear to have pointed noses, a zero slope at the body base, and no variation of wave drag with Mach number. For those bodies having a specified intermediate.diameter (that is, location and magnitude given), the maximum body diameter is shown to be larger, in general, than the specified diameter. It is also shown that, for bodies having a specified maximum diameter, the location of the maximum diameter is not arbitrary but is determined from the ratio of base diameter to maximum diameter.

Classification of Kiwifruit Grades Based on Fruit Shape Using a Single Camera

PubMed Central

Fu, Longsheng; Sun, Shipeng; Li, Rui; Wang, Shaojin

2016-01-01

This study aims to demonstrate the feasibility for classifying kiwifruit into shape grades by adding a single camera to current Chinese sorting lines equipped with weight sensors. Image processing methods are employed to calculate fruit length, maximum diameter of the equatorial section, and projected area. A stepwise multiple linear regression method is applied to select significant variables for predicting minimum diameter of the equatorial section and volume and to establish corresponding estimation models. Results show that length, maximum diameter of the equatorial section and weight are selected to predict the minimum diameter of the equatorial section, with the coefficient of determination of only 0.82 when compared to manual measurements. Weight and length are then selected to estimate the volume, which is in good agreement with the measured one with the coefficient of determination of 0.98. Fruit classification based on the estimated minimum diameter of the equatorial section achieves a low success rate of 84.6%, which is significantly improved using a linear combination of the length/maximum diameter of the equatorial section and projected area/length ratios, reaching 98.3%. Thus, it is possible for Chinese kiwifruit sorting lines to reach international standards of grading kiwifruit on fruit shape classification by adding a single camera. PMID:27376292

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.

Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil

PubMed Central

Nunes, Matheus Henrique

2016-01-01

Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects. PMID:27187074

Artificial Intelligence Procedures for Tree Taper Estimation within a Complex Vegetation Mosaic in Brazil.

PubMed

Nunes, Matheus Henrique; Görgens, Eric Bastos

2016-01-01

Tree stem form in native tropical forests is very irregular, posing a challenge to establishing taper equations that can accurately predict the diameter at any height along the stem and subsequently merchantable volume. Artificial intelligence approaches can be useful techniques in minimizing estimation errors within complex variations of vegetation. We evaluated the performance of Random Forest® regression tree and Artificial Neural Network procedures in modelling stem taper. Diameters and volume outside bark were compared to a traditional taper-based equation across a tropical Brazilian savanna, a seasonal semi-deciduous forest and a rainforest. Neural network models were found to be more accurate than the traditional taper equation. Random forest showed trends in the residuals from the diameter prediction and provided the least precise and accurate estimations for all forest types. This study provides insights into the superiority of a neural network, which provided advantages regarding the handling of local effects.

[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.

Modeling the dynamics of pressure propagation and diameter variation in tree sapwood.

PubMed

Perämäki, Martti; Vesala, Timo; Nikinmaa, Eero

2005-09-01

A non-steady-state model of water tension propagation in tree stems was developed. The model is based on the cohesion theory and the assumption that fluctuating water tension driven by transpiration together with the elasticity of wood cause variations in the diameter of a tree stem. The change in xylem diameter can be linked to water tension in accordance with Hooke's law. The model was tested against field measurements of the diurnal change in xylem diameter at different heights in a 180-year-old Scots pine tree at Hyytiälä, southern Finland. Model predictions agreed well with measurements. The effect of tree dimensions on pressure propagation was examined with the model. The model outcomes were also consistent with results of several field measurements presented in the literature.

Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

PubMed

Huang, Jian-Guo; Stadt, Kenneth J; Dawson, Andria; Comeau, Philip G

2013-01-01

We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2)>0.67) to represent this complex variation in growth as a function of site, size and competition.

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.

Modelling Growth-Competition Relationships in Trembling Aspen and White Spruce Mixed Boreal Forests of Western Canada

PubMed Central

Huang, Jian-Guo; Stadt, Kenneth J.; Dawson, Andria; Comeau, Philip G.

2013-01-01

We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10–25 years for aspen and ≥25 for spruce. Our model demonstrated a remarkable capability (adjusted R2>0.67) to represent this complex variation in growth as a function of site, size and competition. PMID:24204891

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars

PubMed Central

Abarca, J.; Zaror, C.; Monardes, H.; Hermosilla, V.; Muñoz, C.; Cantin, M.

2015-01-01

SUMMARY Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3–5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24–0.33 mm in maxillary first molars and between 0.25–0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully. PMID:25937698

Morphology of the Physiological Apical Foramen in Maxillary and Mandibular First Molars.

PubMed

Abarca, J; Zaror, C; Monardes, H; Hermosilla, V; Muñoz, C; Cantin, M

2014-06-01

Information regarding the anatomy of the physiological apical foramen is limited. Knowing its diameter and shapes contributes to clinical work, specifically to the cleaning and shaping of the apical third. The aim of this ex vivo study was to determine the minimum and maximum diameters and shape of the physiological apical foramen in the roots of maxillary and mandibular first molars. A descriptive study was conducted on 89 recently extracted first molars. Roots 3-5 mm from the apex were sectioned and prepared for analysis at 40× magnification. The minimum and maximum diameters of each physiological foramen were measured using the program Motic Images plus 2.0 ML. The shape of the foramina, classified as round, oval or irregular, was determined by the difference between the maximum and minimum diameters. A total of 174 physiological foramina were analyzed. The average of the minimum and maximum diameters was between 0.24-0.33 mm in maxillary first molars and between 0.25-0.33 mm in mandibular first molars. In maxillary molars, the most common shape of the foramen was oval (50%), then irregular (32%), then round (18%). In mandibular molars, the oval shape was also the most frequent (59%), followed by irregular (23%) and round (18%). The findings of this study regarding the morphology of physiological apical foramina in first molars make it easier for the operator to choose the appropriately-sized instruments to perform endodontic therapy successfully.

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...

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...

A portable NMR sensor to measure dynamic changes in the amount of water in living stems or fruit and its potential to measure sap flow.

PubMed

Windt, Carel W; Blümler, Peter

2015-04-01

Nuclear magnetic resonance (NMR) and NMR imaging (magnetic resonance imaging) offer the possibility to quantitatively and non-invasively measure the presence and movement of water. Unfortunately, traditional NMR hardware is expensive, poorly suited for plants, and because of its bulk and complexity, not suitable for use in the field. But does it need to be? We here explore how novel, small-scale portable NMR devices can be used as a flow sensor to directly measure xylem sap flow in a poplar tree (Populus nigra L.), or in a dendrometer-like fashion to measure dynamic changes in the absolute water content of fruit or stems. For the latter purpose we monitored the diurnal pattern of growth, expansion and shrinkage in a model fruit (bean pod, Phaseolus vulgaris L.) and in the stem of an oak tree (Quercus robur L.). We compared changes in absolute stem water content, as measured by the NMR sensor, against stem diameter variations as measured by a set of conventional point dendrometers, to test how well the sensitivities of the two methods compare and to investigate how well diurnal changes in trunk absolute water content correlate with the concomitant diurnal variations in stem diameter. Our results confirm the existence of a strong correlation between the two parameters, but also suggest that dynamic changes in oak stem water content could be larger than is apparent on the basis of the stem diameter variation alone. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Electron microscopic quantification of collagen fibril diameters in the rabbit medial collateral ligament: a baseline for comparison.

PubMed

Frank, C; Bray, D; Rademaker, A; Chrusch, C; Sabiston, P; Bodie, D; Rangayyan, R

1989-01-01

To establish a normal baseline for comparison, thirty-one thousand collagen fibril diameters were measured in calibrated transmission electron (TEM) photomicrographs of normal rabbit medial collateral ligaments (MCL's). A new automated method of quantitation was used to compare statistically fibril minimum diameter distributions in one midsubstance location in both MCL's from six animals at 3 months of age (immature) and three animals at 10 months of age (mature). Pooled results demonstrate that rabbit MCL's have statistically different (p less than 0.001) mean minimum diameters at these two ages. Interanimal differences in mean fibril minimum diameters were also significant (p less than 0.001) and varied by 20% to 25% in both mature and immature animals. Finally, there were significant differences (p less than 0.001) in mean diameters and distributions from side-to-side in all animals. These mean left-to-right differences were less than 10% in all mature animals but as much as 62% in some immature animals. Statistical analysis of these data demonstrate that animal-to-animal comparisons using these protocols require a large number of animals with appropriate numbers of fibrils being measured to detect small intergroup differences. With experiments which compare left to right ligaments, far fewer animals are required to detect similarly small differences. These results demonstrate the necessity for rigorous control of sampling, an extensive normal baseline and statistically confirmed experimental designs in any TEM comparisons of collagen fibril diameters.

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.

Apparatus and method for classifying fuel pellets for nuclear reactor

DOEpatents

Wilks, Robert S.; Sternheim, Eliezer; Breakey, Gerald A.; Sturges, Jr., Robert H.; Taleff, Alexander; Castner, Raymond P.

1984-01-01

Control for the operation of a mechanical handling and gauging system for nuclear fuel pellets. The pellets are inspected for diameters, lengths, surface flaws and weights in successive stations. The control includes, a computer for commanding the operation of the system and its electronics and for storing and processing the complex data derived at the required high rate. In measuring the diameter, the computer enables the measurement of a calibration pellet, stores that calibration data and computes and stores diameter-correction factors and their addresses along a pellet. To each diameter measurement a correction factor is applied at the appropriate address. The computer commands verification that all critical parts of the system and control are set for inspection and that each pellet is positioned for inspection. During each cycle of inspection, the measurement operation proceeds normally irrespective of whether or not a pellet is present in each station. If a pellet is not positioned in a station, a measurement is recorded, but the recorded measurement indicates maloperation. In measuring diameter and length a light pattern including successive shadows of slices transverse for diameter or longitudinal for length are projected on a photodiode array. The light pattern is scanned electronically by a train of pulses. The pulses are counted during the scan of the lighted diodes. For evaluation of diameter the maximum diameter count and the number of slices for which the diameter exceeds a predetermined minimum is determined. For acceptance, the maximum must be less than a maximum level and the minimum must exceed a set number. For evaluation of length, the maximum length is determined. For acceptance, the length must be within maximum and minimum limits.

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.

Development of welded metal bellows having minimum effective diameter change

NASA Technical Reports Server (NTRS)

Henschel, J. K.; Stevens, J. B.; Harvey, A. C.; Howland, J. S.; Rhee, S. S.

1972-01-01

A program of analysis, design, and fabrication was conducted to develop welded metal bellows having a minimum change in effective diameter for cryogenic turbomachinery face seal applications. Linear analysis of the principle types of bellows provided identification of concepts capable of meeting basic operation requirements. For the 6-inch (.152 m) mean diameter, 1.5-inch free length bellows studied, nonlinear analysis showed that opposed and nested toroidal bellows plates stiffened by means of alternating stiffener rings were capable of maintaining constant effective diameter within 0.3% and 0.1% respectively under the operating conditions of interest. Changes in effective diameter were due principally to bellows axial deflection with pressure differential having a lesser influence. Fabrication problems associated with joining the thin bellows plates to the relatively heavy stiffener rings were encountered and precluded assembly and testing of a bellows core. Fabrication problems are summarized and recommended fabrication methods for future effort are presented.

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...

Sensitivity of 30-cm mercury bombardment ion thruster characteristics to accelerator grid design

NASA Technical Reports Server (NTRS)

Rawlin, V. K.

1978-01-01

The design of ion optics for bombardment thrusters strongly influences overall performance and lifetime. The operation of a 30 cm thruster with accelerator grid open area fractions ranging from 43 to 24 percent, was evaluated and compared with experimental and theoretical results. Ion optics properties measured included the beam current extraction capability, the minimum accelerator grid voltage to prevent backstreaming, ion beamlet diameter as a function of radial position on the grid and accelerator grid hole diameter, and the high energy, high angle ion beam edge location. Discharge chamber properties evaluated were propellant utilization efficiency, minimum discharge power per beam amp, and minimum discharge voltage.

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.

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.

Role of macular hole angle in macular hole closure.

PubMed

Chhablani, Jay; Khodani, Mitali; Hussein, Abdullah; Bondalapati, Sailaja; Rao, Harsha B; Narayanan, Raja; Sudhalkar, Aditya

2015-12-01

To evaluate correlation of various spectral-domain optical coherence tomography (SD-OCT) parameters including macular hole angle as well as various indices with anatomical and visual outcomes after idiopathic macular hole repair surgery. Retrospective study of 137 eyes of 137 patients who underwent idiopathic macular hole repair surgery between January 2008 and January 2014 was performed. Various qualitative parameters such as presence of vitreomacular traction, epiretinal membrane and cystic edges at the macular hole as well as quantitative parameters such as maximum diameter on the apex of the hole, minimum diameter between edges, nasal and temporal vertical height, longest base diameter and macular hole angle between the retinal edge and the retinal pigment epithelium were noted. Indices including hole form factor, Macular Hole Index (MHI), Diameter Hole Index and Tractional Hole Index (THI) were calculated. Univariate and multivariate regression analysis was performed separately for final visual acuity (VA) and type of closure as dependent variable in relation to SD-OCT parameters as independent variables. On multivariate regression only minimum diameter between edges (p≤0.01) and longest base diameter (p≤0.03) were correlated significantly with both, type 1 closure and final VA. Among the indices, significant correlation of MHI (p=0.009) was noted with type of closure and that of THI with final VA (p=0.017). Our study shows no significant correlation between macular hole angle and hole closure. Minimum diameter between the edges and longest diameter of the hole are best predictors of hole closure and postoperative VA. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

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.

7 CFR 51.1216 - Size requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) The numerical count or a count-size based on equivalent tray pack size designations or the minimum... numerical count is not shown the minimum diameter shall be plainly stamped, stenciled, or otherwise marked...

7 CFR 51.1216 - Size requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) The numerical count or a count-size based on equivalent tray pack size designations or the minimum... numerical count is not shown the minimum diameter shall be plainly stamped, stenciled, or otherwise marked...

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...

49 CFR Appendix G to Subchapter B... - Minimum Periodic Inspection Standards

Code of Federal Regulations, 2010 CFR

2010-10-01

... or broken cable strands. (b) Improper clamps or clamping. f. Saddle-Mounts. (1) Method of attachment... axle. (6) A tube-type radial tire without radial tube stem markings. These markings include a red band around the tube stem, the word “radial” embossed in metal stems, or the word “radial” molded in rubber...

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...

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,...

Computer Model for Sizing Rapid Transit Tunnel Diameters

DOT National Transportation Integrated Search

1976-01-01

A computer program was developed to assist the determination of minimum tunnel diameters for electrified rapid transit systems. Inputs include vehicle shape, walkway location, clearances, and track geometrics. The program written in FORTRAN IV calcul...

Selective control of small versus large diameter axons using infrared laser light (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lothet, Emilie H.; Shaw, Kendrick M.; Horn, Charles C.; Lu, Hui; Wang, Yves T.; Jansen, E. Duco; Chiel, Hillel J.; Jenkins, Michael W.

2016-03-01

Sensory information is conveyed to the central nervous system via small diameter unmyelinated fibers. In general, smaller diameter axons have slower conduction velocities. Selective control of such fibers could create new clinical treatments for chronic pain, nausea in response to chemo-therapeutic agents, or hypertension. Electrical stimulation can control axonal activity, but induced axonal current is proportional to cross-sectional area, so that large diameter fibers are affected first. Physiologically, however, synaptic inputs generally affect small diameter fibers before large diameter fibers (the size principle). A more physiological modality that first affected small diameter fibers could have fewer side effects (e.g., not recruiting motor axons). A novel mathematical analysis of the cable equation demonstrates that the minimum length along the axon for inducing block scales with the square root of axon diameter. This implies that the minimum length along an axon for inhibition will scale as the square root of axon diameter, so that lower radiant exposures of infrared light will selectively affect small diameter, slower conducting fibers before those of large diameter. This prediction was tested in identified neurons from the marine mollusk Aplysia californica. Radiant exposure to block a neuron with a slower conduction velocity (B43) was consistently lower than that needed to block a faster conduction velocity neuron (B3). Furthermore, in the vagus nerve of the musk shrew, lower radiant exposure blocked slow conducting fibers before blocking faster conducting fibers. Infrared light can selectively control smaller diameter fibers, suggesting many novel clinical treatments.

Nanohole and dot patterning processes on quartz substrate by R-θ electron beam lithography and nanoimprinting

NASA Astrophysics Data System (ADS)

Watanabe, Tsuyoshi; Taniguchi, Kazutake; Suzuki, Kouta; Iyama, Hiromasa; Kishimoto, Shuji; Sato, Takashi; Kobayashi, Hideo

2016-06-01

Fine hole and dot patterns with bit pitches (bp’s) of less than 40 nm were fabricated in the circular band area of a quartz substrate by R-θ electron beam lithography (EBL), reactive ion etching (RIE), and nanoimprinting. These patterning processes were studied to obtain minimum pitch sizes of hole and dot patterns without pattern collapse. The patterning on the circular band was aimed to apply these patterning processes to future high-density bit-patterned media (BPM) for hard disk drive (HDD) and permanent memory for the long life archiving of digital data. In hole patterning, a minimum-22-nm-bp and 8.2-nm-diameter pattern (1.3 Tbit/in.2) was obtained on a quartz substrate by optimizing the R-θ EBL and RIE processes. Dot patterns were replicated on another quartz substrate by nanoimprinting using a hole-patterned quartz substrate as a master mold followed by RIE. In dot patterning, a minimum-30-nm-bp and 18.5-nm-diameter pattern (0.7 Tbit/in.2) was obtained by introducing new descum conditions. It was observed that the minimum bp of successful patterning increased as the fabrication process proceeded, i.e., from 20 nm bp in the first EBL process to 30 nm bp in the last quartz dot patterning process. From the measured diameters of the patterns, it was revealed that pattern collapse was apt to occur when the value of average diameter plus 3 sigma of diameter was close to the bp. It was suggested that multiple fabrication processes caused the degradation of pattern quality; therefore, hole patterning is more suitable than dot patterning for future applications owing to the lower quality degradation by its simple fabrication process.

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 Feasibility of Two Screws Anterior Fixation for Type II Odontoid Fracture Among Arabs.

PubMed

Marwan, Yousef; Kombar, Osama Rabie; Al-Saeed, Osama; Aleidan, Aljarrah; Samir, Ahmed; Esmaeel, Ali

2016-06-01

Retrospective, cross-sectional study. To evaluate the feasibility of two screws anterior fixation of the odontoid process among Arab adults. Anterior screw fixation is the treatment of choice for type II odontoid fractures. In order to perform the procedure safely, the diameter of the odontoid process should be wide enough to allow for the placement of one or two screws. A retrospective review of 156 computed tomography scans of the cervical spine was done. The included patients were Arabs, adults (at least 18 years old), and had no evidence of upper cervical spine trauma, deformity, infection, tumor, or surgery. The minimum external transverse diameter (METD), minimum internal transverse diameter (MITD), minimum external anteroposterior diameter (MEAD), and minimum internal anteroposterior diameter (MIAD) of the odontoid process were measured. A P value of ≤0.05 was considered as the cutoff level of statistical significance. Our study included 94 (60.3%) males and 62 (39.7%) females. The mean age of the subjects was 37.8 ± 16.9 years (range 18-85). The mean values of the METD, MITD, MEAD, and MIAD were 8.7 ± 1.0 mm, 6.0 ± 1.1 mm, 10.3 ± 1.0 mm, and 7.4 ± 1.1 mm, respectively. Men had larger diameters compared to women. This was statistically significant for METD (P = 0.035) and MEAD (P < 0.001). The METD was <9.0 mm in 95 (60.9%) subjects, while the MITD was <8.0 mm in 153 (98.1%) subjects. These findings were not significantly different between males and females. Two screws anterior fixation of type II odontoid fracture is not feasible among the majority of Arabs. 3.

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.)...

Analysis of lumbar pedicle morphology in degenerative spines using multiplanar reconstruction computed tomography: what can be the reliable index for optimal pedicle screw diameter?

PubMed

Makino, Takahiro; Kaito, Takashi; Fujiwara, Hiroyasu; Yonenobu, Kazuo

2012-08-01

The measurement of transverse pedicle width is still recommended for selecting a screw diameter despite being weakly correlated with the minimum pedicle diameter, except in the upper lumbar spine. The purpose of this study was to reveal the difference between the minimum pedicle diameter and conventional transverse or sagittal pedicle width in degenerative lumbar spines. A total of 50 patients with degenerative lumbar disorders without spondylolysis or lumbar scoliosis of >10° who preoperatively underwent helical CT scans were included. The DICOM data of the scans were reconstructed by imaging software, and the transverse pedicle width (TPW), sagittal pedicle width (SPW), minimum pedicle diameter (MPD), and the cephalocaudal inclination of the pedicles were measured. The mean TPW/SPW/MPD values were 5.46/11.89/5.09 mm at L1, 5.76/10.44/5.39 mm at L2, 7.25/10.23/6.52 mm at L3, 9.01/9.36/6.83 mm at L4, and 12.86/8.95/7.36 mm at L5. There were significant differences between the TPW and MPD at L3, L4, and L5 (p < 0.01) and between the SPW and MPD at all levels (p < 0.01). The MPD was significantly smaller than the TPW and SPW at L3, L4, and L5. The actual measurements of the TPW were not appropriate for use as a direct index for the optimal pedicle screw diameter at these levels. Surgeons should be careful in determining pedicle screw diameter based on plain CT scans especially in the lower lumbar spine.

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

Laser engravings as reason for mechanical failure of titanium-alloyed total hip stems.

PubMed

Kluess, Daniel; Steinhauser, Erwin; Joseph, Micheal; Koch, Ursula; Ellenrieder, Martin; Mittelmeier, Wolfram; Bader, Rainer

2015-07-01

Two revisions of broken β-titanium total hip stems had to be performed in our hospital after 2 and 4 years in situ. Since both fractures were located at the level of a laser engraving, a failure analysis was conducted. Both retrieved hip stems were disinfected and collected in our retrieval database after patient's signed agreement. Each fragment was macroscopically photographed. Fracture surfaces were analyzed using scanning electron microscopy (SEM). Quantification of element content was conducted using energy dispersive X-ray (EDX) analysis. Both stems show fatigue fracture, as displayed by the lines of rest on the fracture surface. The origin of fracture was identified directly at the laser engraving of the company logo at both stems by means of SEM. The EDX analysis showed an oxygen level beneath the laser engraving about twice as high as in the substrate, causing material embrittlement. Laser engravings need to be reduced to a minimum of necessary information, and should be placed at locations with minimum mechanical load. Biomechanical analyses are recommended to identify less loaded areas in implant components to avoid such implant failures.

[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.

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

Menikoff, Ralph

Previously the SURFplus reactive burn model was calibrated for the TATB based explosive PBX 9502. The calibration was based on fitting Pop plot data, the failure diameter and the limiting detonation speed, and curvature effect data for small curvature. The model failure diameter is determined utilizing 2-D simulations of an unconfined rate stick to find the minimum diameter for which a detonation wave propagates. Here we examine the effect of mesh resolution on an unconfined rate stick with a diameter (10mm) slightly greater than the measured failure diameter (8 to 9 mm).

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.

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.

Studies of dished accelerator grids for 30-cm ion thrusters

NASA Technical Reports Server (NTRS)

Rawlin, V. K.

1973-01-01

Eighteen geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

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

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...

29 CFR 1917.121 - Spiral stairways.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 26.67 cm) in height; (3) Minimum loading capability shall be 100 pounds per square foot (4.79kN), and... shall be a minimum of 11/4 inches (3.18 cm) in outside diameter; and (5) Vertical clearance shall be at...

Fiber-optic annular detector array for large depth of field photoacoustic macroscopy.

PubMed

Bauer-Marschallinger, Johannes; Höllinger, Astrid; Jakoby, Bernhard; Burgholzer, Peter; Berer, Thomas

2017-03-01

We report on a novel imaging system for large depth of field photoacoustic scanning macroscopy. Instead of commonly used piezoelectric transducers, fiber-optic based ultrasound detection is applied. The optical fibers are shaped into rings and mainly receive ultrasonic signals stemming from the ring symmetry axes. Four concentric fiber-optic rings with varying diameters are used in order to increase the image quality. Imaging artifacts, originating from the off-axis sensitivity of the rings, are reduced by coherence weighting. We discuss the working principle of the system and present experimental results on tissue mimicking phantoms. The lateral resolution is estimated to be below 200 μm at a depth of 1.5 cm and below 230 μm at a depth of 4.5 cm. The minimum detectable pressure is in the order of 3 Pa. The introduced method has the potential to provide larger imaging depths than acoustic resolution photoacoustic microscopy and an imaging resolution similar to that of photoacoustic computed tomography.

Clinical and radiographic outcomes after total shoulder arthroplasty with an anatomic press-fit short stem.

PubMed

Szerlip, Benjamin W; Morris, Brent J; Laughlin, Mitzi S; Kilian, Christopher M; Edwards, T Bradley

2018-01-01

There is limited information assessing outcomes after total shoulder arthroplasty (TSA) with a press-fit short stem. The purpose of this study was to evaluate early clinical and radiographic outcomes and complications after TSA with an anatomic press-fit short stem. We identified 118 TSAs completed with press-fit short stem and minimum 2-year follow-up; 85 of these patients had a grit-blasted (GB) short stem placed, whereas 33 patients had short stems with proximal porous coating (PPC). Shoulder function scores, active mobility measurements, and radiographs were assessed. The average age at surgery was 66.7 years, with average follow-up of 3 years. Significant improvements were noted for all shoulder function scores and active mobility measurements from the preoperative state to final follow-up (P < .001). There was no stem loosening in any patients with minimum 2-year follow-up; however, 3 female patients with GB stems had gross loosening of their humeral components before 1 year, 2 requiring revision. Radiolucent lines around the humeral component were found in 5.9% without evidence of loosening. Osseous resorption at the medial cortex was noted in 9.3%. Of patients with PPC stems, no patients were observed to have radiolucent lines compared with 8.2% in the GB group (P = .09). TSAs with anatomic press-fit short stem showed significant clinical improvements from the preoperative state to final short-term follow-up, with few complications and minimal radiographic changes. Lack of PPC may contribute to early loosening in patients with poor bone quality. The authors now use a short stem with PPC. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

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.

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.

7 CFR 51.311 - Marking requirements.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Marking Requirements...), grade, and the numerical count or minimum diameter of apples packed in a closed container shall be indicated on the container. For apple lots utilizing the combined diameter/weight designations for Red...

7 CFR 51.311 - Marking requirements.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Marking Requirements...), grade, and the numerical count or minimum diameter of apples packed in a closed container shall be indicated on the container. For apple lots utilizing the combined diameter/weight designations for Red...

Optimal fractal tree-like microchannel networks with slip for laminar-flow-modified Murray's law.

PubMed

Jing, Dalei; Song, Shiyu; Pan, Yunlu; Wang, Xiaoming

2018-01-01

The fractal tree-like branched network is an effective channel design structure to reduce the hydraulic resistance as compared with the conventional parallel channel network. In order for a laminar flow to achieve minimum hydraulic resistance, it is believed that the optimal fractal tree-like channel network obeys the well-accepted Murray's law of β m = N -1/3 (β m is the optimal diameter ratio between the daughter channel and the parent channel and N is the branching number at every level), which is obtained under the assumption of no-slip conditions at the channel wall-liquid interface. However, at the microscale, the no-slip condition is not always reasonable; the slip condition should indeed be considered at some solid-liquid interfaces for the optimal design of the fractal tree-like channel network. The present work reinvestigates Murray's law for laminar flow in a fractal tree-like microchannel network considering slip condition. It is found that the slip increases the complexity of the optimal design of the fractal tree-like microchannel network to achieve the minimum hydraulic resistance. The optimal diameter ratio to achieve minimum hydraulic resistance is not only dependent on the branching number, as stated by Murray's law, but also dependent on the slip length, the level number, the length ratio between the daughter channel and the parent channel, and the diameter of the channel. The optimal diameter ratio decreases with the increasing slip length, the increasing level number and the increasing length ratio between the daughter channel and the parent channel, and decreases with decreasing channel diameter. These complicated relations were found to become relaxed and simplified to Murray's law when the ratio between the slip length and the diameter of the channel is small enough.

Echocolor Doppler morpho-functional study of the jugulo-subclavian confluence in chronic cerebro-spinal venous insufficiency and multiple sclerosis patients.

PubMed

Mandolesi, Sandro; d'Alessandro, Aldo; Desogus, Antonello Ignazio; Ciccone, Marco Matteo; Zito, Annapaola; Stammegna, Immacolata; Niglio, Tarcisio; Orsini, Augusto; Mandolesi, Dimitri; d'Alessandro, Alessandro; Revelli, Luca

2017-01-01

The aim of this work is to measure the mean diameter of the confluence jugulo- subclavian, the impact of different types of jugular confluences and the correlation between the types of confluences and the Valsalva maneuver (jugular reflux) in subjects with Chronic Cerebro-Spinal Venous Insufficiency (CCSVI) and Multiple Sclerosis. We investigated by Echo-Color-Doppler (ECD) 103 subjects (67 F 36M) of mean age 45 ± 12 years (a minimum of 22 to a maximum of 79 years, with a median of 44 and a modal value 42 years), mean EDSS of 4.7 and average disease duration of 12 years. The 103 right jugular veins investigated had an average diameter of 8.4 ± 2.4 mm (minimum 4.0, maximum 14.9 mm; median 7.9; modal value 7.6 mm). Three form types were found: 56 cylindrical, 29 conical and 18 funnel. Valsalva maneuver was positive in 30 patients. The 103 left jugular investigated had an average diameter of 8.9 ± 2.4 mm (minimum 2.8, maximum 14.4 mm; median of 8.8; modal value 8.7 mm). The form types were found: 42 cylindrical, 45 conical and 16 funnel. Valsalva maneuver was positive in 30 patients. The mean diameter of the jugular veins was 8.7 mm. Internal jugular veins with cylindrical morphology have a diameter smaller than other forms; this difference is statistically significant. The different morphology of the jugular vein confluence does not increase the possibility of a reflux because the positive Valsalva maneuvers are not statistically significant when compared to the various types. CCSVI, EchoColorDoppler Map, Jugulo-Subclavian Confluence Diameter.

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.

Preliminary phytochemical screening and in vitro anti-helicobacter pylori activity of extracts of the stem bark of Bridelia micrantha (Hochst., Baill., Euphorbiaceae).

PubMed

Okeleye, Benjamin I; Bessong, Pascal O; Ndip, Roland N

2011-07-25

Helicobacter pylori is a major risk factor for gastritis, ulcers and gastric cancer. This study was aimed to determine the antimicrobial activity of the stem bark of Bridelia. micrantha on H. pylori isolated in South Africa. Extracts and clarithromycin were tested against 31 clinical strains, including a standard strain (NCTC 11638) of H. pylori, by measuring the diameters of the corresponding inhibition zones, followed by determination of the Minimum Inhibitory Concentration (MIC) (using metronidazole, and amoxicillin as control antibiotics) and the rate of kill. Preliminary phytochemical screening was also done. Inhibition zone diameters which ranged from 0-23 mm were observed for all five of the extracts and 0-35 mm for clarithromycin. Marked susceptibility of strains (100%) was noted for the acetone extract (P < 0.05), followed by ethyl acetate extract (93.5%). The MIC₅₀ values ranged from 0.0048 to 0.156 mg/mL for the ethyl acetate extract and 0.0048 to 0.313 mg/mL for the acetone extract. The MIC₉₀ values ranged from 0.0048 to 2.5 mg/mL for the ethyl acetate extract and 0.078 to > 0.625 mg/mL for the acetone extract, respectively. Insignificant statistical difference in potency was observed when comparing the crude ethyl acetate extract to metronidazole and amoxicillin (P > 0.05). Complete killing of strain PE430C by the ethyl acetate extract was observed at 0.1 mg/mL (2 × MIC) and 0.2 mg/mL (4 × MIC) at 66 and 72 h. For strain PE369C, 100% killing was observed at 0.1 mg/mL (2 × MIC) in 66 and 72 h. The ethyl acetate extract could thus be a potential source of lead molecules for the design of new anti-Helicobacter pylori therapies as this study further confirmed the presence of phytochemicals including alkaloids, flavonoids, steroids, tannins and saponins.

Multitemporal observations of identical active dust devils on Mars with the High Resolution Stereo Camera (HRSC) and Mars Orbiter Camera (MOC)

NASA Astrophysics Data System (ADS)

Reiss, D.; Zanetti, M.; Neukum, G.

2011-09-01

Active dust devils were observed in Syria Planum in Mars Observer Camera - Wide Angle (MOC-WA) and High Resolution Stereo Camera (HRSC) imagery acquired on the same day with a time delay of ˜26 min. The unique operating technique of the HRSC allowed the measurement of the traverse velocities and directions of motion. Large dust devils observed in the HRSC image could be retraced to their counterparts in the earlier acquired MOC-WA image. Minimum lifetimes of three large (avg. ˜700 m in diameter) dust devils are ˜26 min, as inferred from retracing. For one of these large dust devil (˜820 m in diameter) it was possible to calculate a minimum lifetime of ˜74 min based on the measured horizontal speed and the length of its associated dust devil track. The comparison of our minimum lifetimes with previous published results of minimum and average lifetimes of small (˜19 m in diameter, avg. min. lifetime of ˜2.83 min) and medium (˜185 m in diameter, avg. min. lifetime of ˜13 min) dust devils imply that larger dust devils on Mars are active for much longer periods of time than smaller ones, as it is the case for terrestrial dust devils. Knowledge of martian dust devil lifetimes is an important parameter for the calculation of dust lifting rates. Estimates of the contribution of large dust devils (>300-1000 m in diameter) indicate that they may contribute, at least regionally, to ˜50% of dust entrainment by dust devils into the atmosphere compared to the dust devils <300 m in diameter given that the size-frequency distribution follows a power-law. Although large dust devils occur relatively rarely and the sediment fluxes are probably lower compared to smaller dust devils, their contribution to the background dust opacity by dust devils on Mars could be at least regionally large due to their longer lifetimes and ability of dust lifting into high atmospheric layers.

Absence of accelerated atherosclerotic disease progression after intracoronary infusion of bone marrow derived mononuclear cells in patients with acute myocardial infarction--angiographic and intravascular ultrasound--results from the TErapia Celular Aplicada al Miocardio Pilot study.

PubMed

Arnold, Roman; Villa, Adolfo; Gutiérrez, Hipólito; Sánchez, Pedro L; Gimeno, Federico; Fernández, Maria E; Gutiérrez, Oliver; Mota, Pedro; Sánchez, Ana; García-Frade, Javier; Fernández-Avilés, Francisco; San Román, Jose A

2010-06-01

We tried to evaluate a putative negative effect on coronary atherosclerosis in patients receiving intracoronary infusion of unfractionated bone marrow mononuclear cells (BMMC) following an acute ST-elevation myocardial infarction. Peripheral blood mononuclear cells or enriched CD133(+) BMMC have been associated with accelerated atherosclerosis of the distal segment of the infarct related artery (IRA). Thirty-seven patients with ST-elevation myocardial infarction from the TECAM pilot study underwent intracoronary infusion of autologous BMMC 9 +/- 3.1 days after onset of symptoms. We compared angiographic changes from baseline to 9 months of follow-up in the distal non-stented segment of the IRA, as well as in the contralateral coronary artery, with a matched control group. A subgroup of 15 treated patients underwent additional IVUS within the distal segment of the IRA. No difference between stem cell and control group were found regarding changes in minimum lumen diameter (0.006 +/- 0.42 vs 0.06 +/- 0.41 mm, P = ns) and the percentage of stenosis (-2.68 +/- 12.33% vs -1.78 +/- 8.75%, P = ns) at follow-up. Likewise, no differences were seen regarding changes in the contralateral artery (minimum lumen diameter -0.004 +/- 0.54 mm vs -0.06 +/- 0.35 mm, P = ns). In the intravascular ultrasound substudy, no changes were demonstrated comparing baseline versus follow-up in maximum area stenosis and plaque volume. In this pilot study, analysis of a subgroup of patients found that intracoronary injection of unfractionated BMMC in patients with acute ST-elevation myocardial infarction was not associated with accelerated atherosclerosis progression at mid term. Prospective, randomised studies in large cohorts with long-term angiographic and intravascular ultrasound follow-up are necessary to determine the safety of this therapy. Copyright 2010 Mosby, Inc. All rights reserved.

7 CFR 932.149 - Modified minimum quality requirements for specified styles of canned olives of the ripe type.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Fragments (Pitted Style Only) Not more than 1.3% average by count Major Stems Not more than 3 HEVM Not more... per 300 grams Major Stems Not more than 3 HEVM Not more than 2 units per sample Broken Pieces and End... Fragments Average of not more than 1 by count per 300 grams Major Stems Not more than 3 HEVM Not more than 2...

7 CFR 932.149 - Modified minimum quality requirements for specified styles of canned olives of the ripe type.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Fragments (Pitted Style Only) Not more than 1.3% average by count Major Stems Not more than 3 HEVM Not more... per 300 grams Major Stems Not more than 3 HEVM Not more than 2 units per sample Broken Pieces and End... Fragments Average of not more than 1 by count per 300 grams Major Stems Not more than 3 HEVM Not more than 2...

7 CFR 932.149 - Modified minimum quality requirements for specified styles of canned olives of the ripe type.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Fragments (Pitted Style Only) Not more than 1.3% average by count Major Stems Not more than 3 HEVM Not more... per 300 grams Major Stems Not more than 3 HEVM Not more than 2 units per sample Broken Pieces and End... Fragments Average of not more than 1 by count per 300 grams Major Stems Not more than 3 HEVM Not more than 2...

7 CFR 932.149 - Modified minimum quality requirements for specified styles of canned olives of the ripe type.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Fragments (Pitted Style Only) Not more than 1.3% average by count Major Stems Not more than 3 HEVM Not more... per 300 grams Major Stems Not more than 3 HEVM Not more than 2 units per sample Broken Pieces and End... Fragments Average of not more than 1 by count per 300 grams Major Stems Not more than 3 HEVM Not more than 2...

7 CFR 932.149 - Modified minimum quality requirements for specified styles of canned olives of the ripe type.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Fragments (Pitted Style Only) Not more than 1.3% average by count Major Stems Not more than 3 HEVM Not more... per 300 grams Major Stems Not more than 3 HEVM Not more than 2 units per sample Broken Pieces and End... Fragments Average of not more than 1 by count per 300 grams Major Stems Not more than 3 HEVM Not more than 2...

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.

Root resistance to cavitation is accurately measured using a centrifuge technique.

PubMed

Pratt, R B; MacKinnon, E D; Venturas, M D; Crous, C J; Jacobsen, A L

2015-02-01

Plants transport water under negative pressure and this makes their xylem vulnerable to cavitation. Among plant organs, root xylem is often highly vulnerable to cavitation due to water stress. The use of centrifuge methods to study organs, such as roots, that have long vessels are hypothesized to produce erroneous estimates of cavitation resistance due to the presence of open vessels through measured samples. The assumption that roots have long vessels may be premature since data for root vessel length are sparse; moreover, recent studies have not supported the existence of a long-vessel artifact for stems when a standard centrifuge technique was used. We examined resistance to cavitation estimated using a standard centrifuge technique and compared these values with native embolism measurements for roots of seven woody species grown in a common garden. For one species we also measured vulnerability using single-vessel air injection. We found excellent agreement between root native embolism and the levels of embolism measured using a centrifuge technique, and with air-seeding estimates from single-vessel injection. Estimates of cavitation resistance measured from centrifuge curves were biologically meaningful and were correlated with field minimum water potentials, vessel diameter (VD), maximum xylem-specific conductivity (Ksmax) and vessel length. Roots did not have unusually long vessels compared with stems; moreover, root vessel length was not correlated to VD or to the vessel length of stems. These results suggest that root cavitation resistance can be accurately and efficiently measured using a standard centrifuge method and that roots are highly vulnerable to cavitation. The role of root cavitation resistance in determining drought tolerance of woody species deserves further study, particularly in the context of climate change. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dendrochronological potential of the alpine shrub Rhododendron nivale on the south-eastern Tibetan Plateau.

PubMed

Liang, Eryuan; Eckstein, Dieter

2009-09-01

Shrubs and dwarf shrubs are wider spread on the Tibetan Plateau than trees and hence offer a unique opportunity to expand the present dendrochronological network into extreme environments beyond the survival limit of trees. Alpine shrublands on the Tibetan Plateau are characterized by rhododendron species. The dendrochronological potential of one alpine rhododendron species and its growth response to the extreme environment on the south-east Tibetan Plateau were investigated. Twenty stem discs of the alpine snowy rhododendron (Rhododendron nivale) were collected close to the tongue of the Zuoqiupu Glacier in south-east Tibet, China. The skeleton plot technique was used for inter-comparison between samples to detect the growth pattern of each stem section. The ring-width chronology was developed by fitting a negative exponential function or a straight line of any slope. Bootstrapping correlations were calculated between the standard chronology and monthly climate data. The wood of snowy rhododendron is diffuse-porous with evenly distributed small-diameter vessels. It has well-defined growth rings. Most stem sections can be visually and statistically cross-dated. The resulting 75-year-long standard ring-width chronology is highly correlated with a timberline fir chronology about 200 km apart, providing a high degree of confidence in the cross-dating. The climate/growth association of alpine snowy rhododendron and of this timberline fir is similar, reflecting an impact of monthly mean minimum temperatures in November of the previous year and in July during the year of ring formation. The alpine snowy rhododendron offers new research directions to investigate the environmental history of the Tibetan Plateau in those regions where up to now there was no chance of applying dendrochronology.

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.

Spatial variations in Eulemur fulvus rufus and Lepilemur mustelinus densities in Madagascar.

PubMed

Lehman, Shawn M

2007-01-01

I present data on variations in Eulemur fulvus rufus and Lepilemur mustelinus densities as well as tree characteristics (height, diameter and stem frequency) between edge and interior forest habitats in southeastern Madagascar. Line transect surveys were conducted from June 2003 to November 2005 in edge and interior forest habitats in the Vohibola III Classified Forest. Although E. f. rufus densities were significantly lower in edge habitats than in interior habitats, density estimates for L. mustelinus did not differ significantly between habitats. Trees in edge habitats were significantly shorter, had smaller diameters and had lower stem frequencies (for those >25 cm in diameter) than trees in interior habitats. Spatial characteristics of food abundance and quality may explain lemur density patterns in Vohibola III. Low E. f. rufus densities may reduce seed dispersal in edge habitats, which has important consequences for the long-term viability of forest ecosystems in Madagascar. Copyright (c) 2007 S. Karger AG, Basel.

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.

Re-Introduction of Transmembrane Serine Residues Reduce the Minimum Pore Diameter of Channelrhodopsin-2

PubMed Central

Richards, Ryan; Dempski, Robert E.

2012-01-01

Channelrhodopsin-2 (ChR2) is a microbial-type rhodopsin found in the green algae Chlamydomonas reinhardtii. Under physiological conditions, ChR2 is an inwardly rectifying cation channel that permeates a wide range of mono- and divalent cations. Although this protein shares a high sequence homology with other microbial-type rhodopsins, which are ion pumps, ChR2 is an ion channel. A sequence alignment of ChR2 with bacteriorhodopsin, a proton pump, reveals that ChR2 lacks specific motifs and residues, such as serine and threonine, known to contribute to non-covalent interactions within transmembrane domains. We hypothesized that reintroduction of the eight transmembrane serine residues present in bacteriorhodopsin, but not in ChR2, will restrict the conformational flexibility and reduce the pore diameter of ChR2. In this work, eight single serine mutations were created at homologous positions in ChR2. Additionally, an endogenous transmembrane serine was replaced with alanine. We measured kinetics, changes in reversal potential, and permeability ratios in different alkali metal solutions using two-electrode voltage clamp. Applying excluded volume theory, we calculated the minimum pore diameter of ChR2 constructs. An analysis of the results from our experiments show that reintroducing serine residues into the transmembrane domain of ChR2 can restrict the minimum pore diameter through inter- and intrahelical hydrogen bonds while the removal of a transmembrane serine results in a larger pore diameter. Therefore, multiple positions along the intracellular side of the transmembrane domains contribute to the cation permeability of ChR2. PMID:23185520

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.

Comparison of Hydroxyapatite-coated stems in total hip arthroplasty after a minimum 10-years follow-up.

PubMed

Gallo, J; Landor, I; Cechová, I; Jahoda, D

2008-10-01

PURPOSE OF THE STUDY Hydroxypatite coating (HAC) was introduced into total hip arthroplasty (THA) practice to improve the fixation interface between bone and prosthesis. To test this assumption however, long-term follow-up investigations are needed. In this study, we present data for two consecutive series of THA stems with HAC and a minimum ten-year follow-up. MATERIAL Overall, 249 patients (271 hips) were included in the study, of these 122 (135 hips) had Walter hip arthroplasty (WHA group) with a two-layered TiO2/HAC at the proximal part of the stem and 127 (136 hips) had ABG I prostheses (ABG I group) with a single-layered HAC at the proximal part of the stem. Mean length of follow-up was 11.4 years (0.8-13) and 9.8 years (4-12) in WHA and ABG I groups, respectively. Mean age at the time of surgery was 62 years (23-79) and 47 years (21-65) in WHA and ABG I groups, respectively. METHODS Probabilities of implant survival were estimated using the Kaplan-Meier method. Radiographic data were included to construct the worst-case scenario. Differences in survival curves were evaluated by Gehan's Wilcoxon test. Harris hip score was used to compare preoperative status with that of final follow-up. RESULTS The overall survival of WHA was significantly better than the ABG I (0.85 versus 0.66; p < 0.05). The main reason for a high revision rate in ABG I was periprosthetic osteolysis followed by aseptic loosening. With regard to stems, the survivorship curve for the Walter stem was significantly better than for the ABG I stem even when radiographic results were included (p = 0.0002). In the WHA group, two stems (1.5%) were revised due to sepsis, in contrast to thirty-one stems (23.5%) revised in the ABG I group due to osteolysis and aseptic loosening (p < 0.05). Significant improvement was achieved in both groups under study in terms of Harris hip score. DISCUSSION Data presented here appear surprising at first glance because the differences between the stems under study are only minor. The failure in ABG I was most probably caused by poor polyethylene quality and poor locking mechanism of polyethylene liner in the metallic shell. In addition, HAC used in ABG I prosthesis was not able to prevent the development of polyethylene disease stimulated by high wear rate. CONCLUSION This study revealed excellent survivorship for WHA stems after a minimum ten-year survival and significantly poorer survivorship for the ABG I stems.This may be explained at least particularly by combined two-layered HAC used in WHA stems which provide simultaneously endurable bone interlocking and effective barrier against expansion of polyethylene disease.

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.

Analysis of glycosylated flavonoids extracted from sweet-cherry stems, as antibacterial agents against pathogenic Escherichia coli isolates.

PubMed

Aires, Alfredo; Dias, Carla; Carvalho, Rosa; Saavedra, Maria José

2017-01-01

The aim of this study was to evaluate the bioactivity of flavonoids extracted from sweet-cherry stems which are often used by a traditional system of medicine to treat gastro-intestinal and urinary tract infections but lacking any consistent scientific evidence; moreover the information about the class of phenolics, their content and the potential bioactivity of such material is very scarce. Thus, in this context, we have set a research study in which we evaluated the profile and content of phenolics extracted from sweet-cherry stems through a conventional (70ºC and 20 min) and ultrasound assisted extraction (40 kHz, room temperature and 20 min). The extracts were phytochemically characterized by using an HPLC-DAD-UV/VIS system and assayed by an in vitro minimum inhibitory concentration (MIC) bioassay against Escherichia coli isolates. Simultaneously, the total antioxidant activities were measured using the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS •+ ) radical cation assay. Our results indicate that sweet-cherry stems have a high content of sakuranetin, ferulic acid, p-coumaric acid, p-coumaroylquinic acid, chlorogenic acid and its isomer neochlorogenic acid. Their average levels were highly affected by the extraction method used (p<0.001). The same trend was observed for total antioxidant activity and MIC values. The extracts produced with ultrasounds presented both, a higher total antioxidant activity and a lower minimum inhibitory concentration. Statistical analyses of our results showed a significant correlation (p<0.01) of total antioxidant activity and minimum inhibitory concentration with phenolics present in the extracts studied. Thus, we can conclude that cherry stems can be further exploited to purify compounds and produce coproducts with enhanced biologically added value for pharmaceutical industry.

Influence of different types of pulp treatment during isolation in the obtention of human dental pulp stem cells

PubMed Central

Viña-Almunia, Jose; Borras, Consuelo; Gambini, Juan; El Alamy, Marya; Viña, Jose

2016-01-01

Background Different methods have been used in order to isolate dental pulp stem cells. The aim of this study was to study the effect of different types of pulp treatment during isolation, under 3% O2 conditions, in the time needed and the efficacy for obtaining dental pulp stem cells. Material and Methods One hundred and twenty dental pulps were used to isolate dental pulp stem cells treating the pulp tissue during isolation using 9 different methods, using digestive, disgregation, or mechanical agents, or combining them. The cells were positive for CD133, Oct4, Nestin, Stro-1, CD34 markers, and negative for the hematopoietic cell marker CD-45, thus confirming the presence of mesenchymal stem cells. The efficacy of dental pulp stem cells obtention and the minimum time needed to obtain such cells comparing the 9 different methods was analyzed. Results Dental pulp stem cells were obtained from 97 of the 120 pulps used in the study, i.e. 80.8% of the cases. They were obtained with all the methods used except with mechanical fragmentation of the pulp, where no enzymatic digestion was performed. The minimum time needed to isolate dental pulp stem cells was 8 hours, digesting with 2mg/ml EDTA for 10 minutes, 4mg/ml of type I collagenase, 4mg/ml of type II dispase for 40 minutes, 13ng/ml of thermolysine for 40 minutes and sonicating the culture for one minute. Conclusions Dental pulp stem cells were obtained in 97 cases from a series of 120 pulps. The time for obtaining dental pulp stem cells was reduced maximally, without compromising the obtention of the cells, by combining digestive, disgregation, and mechanical agents. Key words:Dental pulp stem cells, mesenchymal stem cells, isolation method. PMID:26946201

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.

7 CFR 51.320 - Diameter.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., CERTIFICATION, AND STANDARDS) United States 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... dimension of the apple determined by passing the apple through a round opening in any position. U.S...

7 CFR 51.320 - Diameter.

Code of Federal Regulations, 2014 CFR

2014-01-01

..., CERTIFICATION, AND STANDARDS) United States 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... dimension of the apple determined by passing the apple through a round opening in any position. U.S...

7 CFR 51.1859 - Size.

Code of Federal Regulations, 2011 CFR

2011-01-01

... cherry tomatoes and Pyriforme type tomatoes commonly referred to as pear shaped tomatoes, and other... Standards for Fresh Tomatoes 1 Size § 51.1859 Size. (a) The size of tomatoes packed in any standard type... measurement for minimum diameter shall be the largest diameter of the tomato measured at right angles to a...

7 CFR 51.1859 - Size.

Code of Federal Regulations, 2010 CFR

2010-01-01

... cherry tomatoes and Pyriforme type tomatoes commonly referred to as pear shaped tomatoes, and other... Standards for Fresh Tomatoes 1 Size § 51.1859 Size. (a) The size of tomatoes packed in any standard type... measurement for minimum diameter shall be the largest diameter of the tomato measured at right angles to a...

7 CFR 51.2952 - Size specifications.

Code of Federal Regulations, 2011 CFR

2011-01-01

... specifications. Size shall be specified in accordance with the facts in terms of one of the following classifications: (a) Mammoth size. Mammoth size means walnuts of which not over 12 percent, by count, pass through... foregoing classifications, size of walnuts may be specified in terms of minimum diameter, or minimum and...

7 CFR 51.2952 - Size specifications.

Code of Federal Regulations, 2010 CFR

2010-01-01

... specifications. Size shall be specified in accordance with the facts in terms of one of the following classifications: (a) Mammoth size. Mammoth size means walnuts of which not over 12 percent, by count, pass through... foregoing classifications, size of walnuts may be specified in terms of minimum diameter, or minimum and...

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.

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.

The provision of clearances accuracy in piston - cylinder mating

NASA Astrophysics Data System (ADS)

Glukhov, V. I.; Shalay, V. V.

2017-08-01

The paper is aimed at increasing the quality of the pumping equipment in oil and gas industry. The main purpose of the study is to stabilize maximum values of productivity and durability of the pumping equipment based on the selective assembly of the cylinder-piston kinematic mating by optimization criterion. It is shown that the minimum clearance in the piston-cylinder mating is formed by maximum material dimensions. It is proved that maximum material dimensions are characterized by their own laws of distribution within the tolerance limits for the diameters of the cylinder internal mirror and the outer cylindrical surface of the piston. At that, their dispersion zones should be divided into size groups with a group tolerance equal to half the tolerance for the minimum clearance. The techniques for measuring the material dimensions - the smallest cylinder diameter and the largest piston diameter according to the envelope condition - are developed for sorting them into size groups. Reliable control of the dimensions precision ensures optimal minimum clearances of the piston-cylinder mating in all the size groups of the pumping equipment, necessary for increasing the equipment productivity and durability during the production, operation and repair processes.

[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.

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.

Standards for Technological Literacy and STEM Education Delivery through Career and Technical Education Programs

ERIC Educational Resources Information Center

Asunda, Paul A.

2012-01-01

At a minimum, employers rely on career and technical education (CTE) and workforce training systems to supply workers able to perform in their jobs. In CTE classes that seek to integrate science, technology, engineering, and mathematics (STEM) concepts, it falls to the instructors to design and sequence the learning experiences that will promote…

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.

An analytical investigation of a conceptual design for the station transverse boom rotary joint structure

NASA Technical Reports Server (NTRS)

Lake, M. S.; Bush, H. G.

1986-01-01

A study was conducted to define an annular ring, discrete roller assembly concept for the space station transverse boom rotary joint. The concept was analyzed using closed-form and finite element techniques, to size structural members for a range of joint diameters and to determine necessary equivalent stiffnesses for the roller assemblies. Also, a mass study of the system was conducted to determine its practicality, and maximum loads in the joint were identified. To obtain the optimum balance between high stiffness and low structural mass in the design of the rotary joint, it is necessary to maximize the diameter of the annular ring within operational constraints (i.e., shuttle cargo bay size). Further, a rotary joint designed with the largest possible ring diameter will result in minimum operational loads in both the roller assemblies and the transition truss members while also allowing minimum design stiffnesses for the roller assemblies.

Relationship between fluid bed aerosol generator operation and the aerosol produced

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

Carpenter, R.L.; Yerkes, K.

1980-12-01

The relationships between bed operation in a fluid bed aerosol generator and aerosol output were studied. A two-inch diameter fluid bed aerosol generator (FBG) was constructed using stainless steel powder as a fluidizing medium. Fly ash from coal combustion was aerosolized and the influence of FBG operating parameters on aerosol mass median aerodynamic diameter (MMAD), geometric standard deviation (sigma/sub g/) and concentration was examined. In an effort to extend observations on large fluid beds to small beds using fine bed particles, minimum fluidizing velocities and elutriation constant were computed. Although FBG minimum fluidizing velocity agreed well with calculations, FBG elutriationmore » constant did not. The results of this study show that the properties of aerosols produced by a FBG depend on fluid bed height and air flow through the bed after the minimum fluidizing velocity is exceeded.« less

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...

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2014 CFR

2014-04-01

... drain piping for each toilet shall be vented by a 11/2 inch minimum diameter vent or rectangular vent of..., connected to the toilet drain by one of the following methods: (i) A 11/2 inch diameter (min.) individual vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280...

7 CFR 51.2113 - Size requirements.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of range in count of whole almond kernels per ounce or in terms of minimum, or minimum and maximum diameter. When a range in count is specified, the whole kernels shall be fairly uniform in size, and the average count per ounce shall be within the range specified. Doubles and broken kernels shall not be used...

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.

Factors affecting minimum push and pull forces of manual carts.

PubMed

Al-Eisawi, K W; Kerk, C J; Congleton, J J; Amendola, A A; Jenkins, O C; Gaines, W

1999-06-01

The minimum forces needed to manually push or pull a 4-wheel cart of differing weights with similar wheel sizes from a stationary state were measured on four floor materials under different conditions of wheel width, diameter, and orientation. Cart load was increased from 0 to 181.4 kg in increments of 36.3 kg. The floor materials were smooth concrete, tile, asphalt, and industrial carpet. Two wheel widths were tested: 25 and 38 mm. Wheel diameters were 51, 102, and 153 mm. Wheel orientation was tested at four levels: F0R0 (all four wheels aligned in the forward direction), F0R90 (the two front wheels, the wheels furthest from the cart handle, aligned in the forward direction and the two rear wheels, the wheels closest to the cart handle, aligned at 90 degrees to the forward direction), F90R0 (the two front wheels aligned at 90 degrees to the forward direction and the two rear wheels aligned in the forward direction), and F90R90 (all four wheels aligned at 90 degrees to the forward direction). Wheel width did not have a significant effect on the minimum push/pull forces. The minimum push/pull forces were linearly proportional to cart weight, and inversely proportional to wheel diameter. The coefficients of rolling friction were estimated as 2.2, 2.4, 3.3, and 4.5 mm for hard rubber wheels rolling on smooth concrete, tile, asphalt, and industrial carpet floors, respectively. The effect of wheel orientation was not consistent over the tested conditions, but, in general, the smallest minimum push/pull forces were measured with all four wheels aligned in the forward direction, whereas the largest minimum push/pull forces were measured when all four wheels were aligned at 90 degrees to the forward direction. There was no significant difference between the push and pull forces when all four wheels were aligned in the forward direction.

Neutral lipids and phospholipids in Scots pine (Pinus sylvestris) sapwood and heartwood.

PubMed

Piispanen, R; Saranpää, P

2002-06-01

Variations in the concentration and composition of triacylglycerols, free fatty acids and phospholipids were analyzed in Scots pine (Pinus sylvestris L.) trees at five sites. Disks were taken at breast height or at a height of 4 m from the stems of 81 trees differing in diameter and growth rate. The mean concentration of triacylglycerols in sapwood was 26 mg g(-1) dry mass; however, variation among trees was large (16-51 mg g(dm)(-1)). The concentration of triacylglycerols was slightly larger at 4 m height in the stem than at breast height. Concentrations of triacylglycerols did not differ between the sapwood of young and small-diameter stems (DBH < 12 cm) and the sapwood of old stems (DBH > 36 cm). Concentrations of free fatty acids were negligible in the outer sapwood, but ranged between 5 and 18 mg g(dm)(-1) in the heartwood. The most abundant fatty acids of triacylglycerols were oleic (18:1), linoleic (18:2omega6, 18:2Delta5,9), linolenic (pinolenic, 18:3Delta5,9,12 and 18:3omega3) and eicosatrienoic acid (20:3Delta5,11,14 and 20:3omega6). The concentration of linoleic acid comprised 39-46% of the triacylglycerol fatty acids and the concentration was higher in the slow-growing stem from northern Finland than in the stems from southern Finland. Major phospholipids were detected only in sapwood, and only traces of lipid phosphorus were detected in heartwood.

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.

Heat Transfer Processes Linking Fire Behavior and Tree Mortality

NASA Astrophysics Data System (ADS)

Michaletz, S. T.; Johnson, E. A.

2004-12-01

Traditional methods for predicting post-fire tree mortality employ statistical models which neglect the processes linking fire behavior to physiological mortality mechanisms. Here we present a physical process approach which predicts tree mortality by linking fireline intensity with lateral (vascular cambium) and apical (vegetative bud) meristem necrosis. We use a linefire plume model with independently validated conduction and lumped capacitance heat transfer analyses to predict lethal meristem temperatures in tree stems, branches, and buds. These models show that meristem necrosis in large diameter (Bi ≥ 0.3) stems/branches is governed by meristem height, bark thickness, and bark water content, while meristem necrosis in small diameter (Bi < 0.3) branches/buds is governed by meristem height, branch/bud size, branch/bud water content, and foliage architecture. To investigate effects of interspecfic variation in these properties, we compare model results for Picea glauca (Moench) Voss and Pinus contorta Loudon var. latifolia Engelm. at fireline intensities from 50 to 3000 kWm-1. Parameters are obtained from allometric models which relate stem/branch diameter to bark thickness and height, as well as bark and bud water content data collected in the southern Canadian Rocky Mountains. Variation in foliage architecture is quantified using forced convection heat transfer coefficients measured in a laminar flow wind tunnel at Re from 100 to 2000, typical for branches/buds in a linefire plume. Results indicate that in unfoliated stems/branches, P. glauca meristems are more protected due to thicker bark, whereas in foliated branches/buds, P. contorta meristems are more protected due to larger bud size and foliage architecture.

Managing white and Lutz spruce stands in south-central Alaska for increased resistance to spruce beetle.

Treesearch

J.S. Hard; E.H. Holsten

1985-01-01

Thinning is recommended for maintaining vigorous tree growth to minimize losses caused by spruce beetles (Dendroctonus rufipenni Kirby) and windthrow in residual stands of spruce in south-central Alaska. The anatomy of conifer stems, the variation in stem diameter growth, and the variability of tree response to wounding are discussed to explain why...

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.

Intraoperative Assessment of Esophagogastric Junction Distensibility During Laparoscopic Heller Myotomy.

PubMed

DeHaan, Reece K; Frelich, Matthew J; Gould, Jon C

2016-04-01

We sought to characterize the changes in esophagogastric junction (EGJ) distensibility during Heller Myotomy with Dor fundoplication using the EndoFLIP device. Intraoperative distensibility measurements on 14 patients undergoing Heller myotomy with Dor fundoplication were conducted over an 18-month period. Minimum esophageal diameter, cross-sectional areas, and distensibility index were measured at 30 and 40 mL catheter volumes before myotomy, postmyotomy, and following Dor fundoplication. Distensibility index is defined as the narrowest cross-sectional area divided by the corresponding pressure expressed in mm/mm Hg. Heller myotomy was found to lead to significant changes in the distensibility characteristics of the EGJ. Minimum esophageal diameter and EGJ distensibility increased significantly with Heller myotomy.

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...

[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).

Method for estimating potential tree-grade distributions for northeastern forest species

Treesearch

Daniel A. Yaussy; Daniel A. Yaussy

1993-01-01

Generalized logistic regression was used to distribute trees into four potential tree grades for 20 northeastern species groups. The potential tree grade is defined as the tree grade based on the length and amount of clear cuttings and defects only, disregarding minimum grading diameter. The algorithms described use site index and tree diameter as the predictive...

Small-diameter roundwood, strong-post W-beam guardrail systems

Treesearch

David Kretschmann; Ronald Faller; John Reid; Jason Hascall; Dean Sicking; John Rohde

2006-01-01

Round guardrail posts may provide an important value-added option for small-diameter thinnings. Such posts require minimum processing and are believed to have higher strength for the equivalent rectangular volume. The resulting value-added product may bring a higher return compared to lumber. The obstacles to immediate utilization of ponderosa pine and Douglas-fir...

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.

Angiographic predictors of 3-year patency of bypass grafts implanted on the right coronary artery system: a prospective randomized comparison of gastroepiploic artery, saphenous vein, and right internal thoracic artery grafts.

PubMed

Glineur, David; D'hoore, William; de Kerchove, Laurent; Noirhomme, Philippe; Price, Joel; Hanet, Claude; El Khoury, Gebrine

2011-11-01

Saphenous vein, in situ right gastroepiploic artery, and right internal thoracic artery grafts are routinely used to revascularize the right coronary artery. Little is known about the predictive value of objective preoperative angiographic parameters on midterm graft patency. We prospectively enrolled 210 consecutive patients undergoing coronary revascularization. Revascularization of the right coronary artery was randomly performed with the saphenous vein grafts in 81 patients and the right gastroepiploic artery in 92 patients. During the same study period, 37 patients received right coronary artery revascularization with the right internal thoracic artery used in a Y-composite fashion. All patients underwent a protocol-driven coronary angiogram 3 years after surgery. Preoperative angiographic parameters included minimum lumen diameter percent stenosis measured by quantitative angiography. A graft was considered "not functional" with patency scores of 0 to 2 and "functional" with patency scores of 3 or 4. Angiographic follow-up was 100% complete. A significant difference in the distribution of flow patterns was observed in the 3 groups. In multivariate analysis, the use of a saphenous vein graft was associated with superior graft functionality compared with the other conduits (odds ratio, 6.1; 95% confidence interval, 2.4-15). Graft function was negatively influenced by the minimum lumen diameter (odds ratio, 0.11; confidence interval, 0.05-0.25). In the right gastroepiploic artery and right internal thoracic artery groups, the proportion of functional grafts was higher when the minimum lumen diameter was below a threshold value in the third minimum lumen diameter quartile (0.64-1.30 mm). Preoperative angiography predicts graft patency in the right gastroepiploic artery and right internal thoracic artery, whereas the flow pattern in saphenous vein grafts is significantly less influenced by quantitative angiographic parameters. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

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.

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.

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.

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...

The impact of annual and seasonal rainfall patterns on growth and phenology of emergent tree species in Southeastern Amazonia, Brazil

Treesearch

James Grogan; Mark Schulze

2012-01-01

Understanding tree growth in response to rainfall distribution is critical to predicting forest and species population responses to climate change. We investigated inter-annual and seasonal variation in stem diameter by three emergent tree species in a seasonally dry tropical forest in southeast Pará, Brazil. Annual diameter growth rates by Swietenia macrophylla...

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.

Investigating the use of small-diameter softwood as guardrail posts: static test results

Treesearch

David E. Kretschmann; Ron Faller; Jason Hascall; John Reid; Dean Sicking; John Rohde; Dick Shilts; Tim Nelson

2007-01-01

Round guardrail posts may provide an important value added option for small-diameter thinnings. Such posts require minimum processing and have been shown to have higher strength compared to the equivalent rectangular volume. The resulting value-added product may bring a higher return compared to lumber. The obstacles to immediate utilization of ponderosa pine and...

Magnetic levitation of condensed hydrogen

NASA Technical Reports Server (NTRS)

Paine, C. G.; Seidel, G. M.

1991-01-01

Liquid and solid molecular hydrogen has been levitated using a pair of small superconducting solenoids. The hydrogen samples, up to 3 mm in dimension, were trapped in a magnetic potential having either a discrete minimum or a minimum in the form of a ring 1 cm in diameter. The hydrogen could be moved about in the magnetic trap by applying an electric field.

50 CFR 223.207 - Approved TEDs.

Code of Federal Regulations, 2010 CFR

2010-10-01

... with a minimum outside diameter of 1 inch (2.54 cm) and a minimum wall thickness of 1/8 inch (0.32 cm... the TED frame minus 4 inches (10.2 cm) on both sides of the grid, when measured as a straight line... opening cannot be narrower than the outside width of the grid minus 4 inches (10.2 cm) on both sides of...

46 CFR 160.062-5 - Markings.

Code of Federal Regulations, 2013 CFR

2013-10-01

...″ stainless steel tag of a minimum thickness of 0.032 inches. This tag shall be permanently attached to a hydraulic release with a single stainless steel link made of wire 3/16″ in diameter. This link shall provide... of manufacture with a 2″ by 31/2″ stainless steel tag of a minimum thickness of 0.032 inch. This tag...

46 CFR 160.062-5 - Markings.

Code of Federal Regulations, 2014 CFR

2014-10-01

...″ stainless steel tag of a minimum thickness of 0.032 inches. This tag shall be permanently attached to a hydraulic release with a single stainless steel link made of wire 3/16″ in diameter. This link shall provide... of manufacture with a 2″ by 31/2″ stainless steel tag of a minimum thickness of 0.032 inch. This tag...

46 CFR 160.062-5 - Markings.

Code of Federal Regulations, 2012 CFR

2012-10-01

...″ stainless steel tag of a minimum thickness of 0.032 inches. This tag shall be permanently attached to a hydraulic release with a single stainless steel link made of wire 3/16″ in diameter. This link shall provide... of manufacture with a 2″ by 31/2″ stainless steel tag of a minimum thickness of 0.032 inch. This tag...

Experimental Investigation of Minimum Quantity Lubrication in Meso-scale Milling with Varying Tool Diameter

NASA Astrophysics Data System (ADS)

Yusof, M. Q. M.; Harun, H. N. S. B.; Bahar, R.

2018-01-01

Minimum quantity lubrication (MQL) is a method that uses a very small amount of liquid to reduce friction between cutting tool and work piece during machining. The implementation of MQL machining has become a viable alternative to flood cooling machining and dry machining. The overall performance has been evaluated during meso-scale milling of mild steel using different diameter milling cutters. Experiments have been conducted under two different lubrication condition: dry and MQL with variable cutting parameters. The tool wear and its surface roughness, machined surfaces microstructure and surface roughness were observed for both conditions. It was found from the results that MQL produced better results compared to dry machining. The 0.5 mm tool has been selected as the most optimum tool diameter to be used with the lowest surface roughness as well as the least flank wear generation. For the workpiece, it was observed that the cutting temperature possesses crucial effect on the microstructure and the surface roughness of the machined surface and bigger diameter tool actually resulted in higher surface roughness. The poor conductivity of the cutting tool may be one of reasons behind.

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.

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...

Vacancy Mediated Mechanism of Nitrogen Substitution in Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Menon, Madhu; Sadanadan, Bindu; Rao, Apparao M.

2003-01-01

Nitrogen substitution reaction in a graphene sheet and carbon nanotubes of different diameter are investigated using the generalized tight-binding molecular dynamics method. The formation of a vacancy in curved graphene sheet or a carbon nanotube is found to cause a curvature dependent local reconstruction of the surface. Our simulations and analysis show that vacancy mediated N substitution (rather than N chemisorption) is favored on the surface of nanotubes with diameter larger than 8 nm. This predicted value of the critical minimum diameter for N incorporation is confirmed by experimental results presented.

Thermal Interference Fit Anode Assembly for Cathodic Protection

DTIC Science & Technology

2018-02-22

than an inside diameter of the cylindrical anode, is subject to the low temperature for a minimum of six hours and preferably twenty- four hours to...degrees Fahrenheit after a minimum of six hours and preferably twenty-four hours. The anode 10 is immediately fused to the mounting bolt 20 by hand...degrees Fahrenheit after a minimum of six hours and preferably twenty-four hours. The anode is then hand pressed onto the mounting bolt to bottom out on the non-anodized face in order to form a single fused assembly.

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).

A diameter growth model for the SRS FIA

Treesearch

David Gartner

2015-01-01

Changes in the national Forest Inventory and Analysis (FIA) processing system required the Southern Research Station’s FIA unit to create a diameter growth model to estimate the growth of trees that could not be measured at both ends of a measurement interval. Examples of such trees are trees that have died or been harvested, and trees that grow over the minimum...

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

Comparison of intravascular ultrasound to contrast-enhanced 64-slice computed tomography to assess the significance of angiographically ambiguous coronary narrowings.

PubMed

Okabe, Teruo; Weigold, Wm Guy; Mintz, Gary S; Roswell, Robert; Joshi, Subodh; Lee, Sung Yun; Lee, Bongryeol; Steinberg, Daniel H; Roy, Probal; Slottow, Tina L Pinto; Smith, Kimberly; Torguson, Rebecca; Xue, Zhenyi; Satler, Lowell F; Kent, Kenneth M; Pichard, Augusto D; Weissman, Neil J; Lindsay, Joseph; Waksman, Ron

2008-10-15

The efficacy of contrast-enhanced multislice computed tomography (MSCT) for assessment of ambiguous lesions is unknown. We compared both quantitative coronary angiography (QCA) and MSCT to the gold standard for a significant stenosis-minimum luminal area (MLA) by intravascular ultrasound (IVUS)-in 51 patients (64 +/- 10 years old, 19 men) with 69 angiographically ambiguous, nonleft main lesions. The MSCT was performed 17 +/- 18 days before IVUS analysis. Overall diameter stenosis by QCAwas 51.0 +/- 9.8%; 39 of 51 patients (76%) eventually underwent revascularization (38 by percutaneous coronary intervention and 1 by coronary artery bypass graft). By univariate analysis, minimum luminal diameter, MLA, lumen visibility by MSCT, and minimum luminal diameter by QCA were significant predictors of MLA by IVUS

Fatigue acceptance test limit criterion for larger diameter rolled thread fasteners

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

Kephart, A.R.

1997-05-01

This document describes a fatigue lifetime acceptance test criterion by which studs having rolled threads, larger than 1.0 inches in diameter, can be assured to meet minimum quality attributes associated with a controlled rolling process. This criterion is derived from a stress dependent, room temperature air fatigue database for test studs having a 0.625 inch diameter threads of Alloys X-750 HTH and direct aged 625. Anticipated fatigue lives of larger threads are based on thread root elastic stress concentration factors which increase with increasing thread diameters. Over the thread size range of interest, a 30% increase in notch stress ismore » equivalent to a factor of five (5X) reduction in fatigue life. The resulting diameter dependent fatigue acceptance criterion is normalized to the aerospace rolled thread acceptance standards for a 1.0 inch diameter, 0.125 inch pitch, Unified National thread with a controlled Root radius (UNR). Testing was conducted at a stress of 50% of the minimum specified material ultimate strength, 80 Ksi, and at a stress ratio (R) of 0.10. Limited test data for fastener diameters of 1.00 to 2.25 inches are compared to the acceptance criterion. Sensitivity of fatigue life of threads to test nut geometry variables was also shown to be dependent on notch stress conditions. Bearing surface concavity of the compression nuts and thread flank contact mismatch conditions can significantly affect the fastener fatigue life. Without improved controls these conditions could potentially provide misleading acceptance data. Alternate test nut geometry features are described and implemented in the rolled thread stud specification, MIL-DTL-24789(SH), to mitigate the potential effects on fatigue acceptance data.« less

Preliminary phytochemical screening and in vitro anti-Helicobacter pylori activity of acetone and aqueous extracts of the stem bark of Sclerocarya birrea (Anacardiaceae).

PubMed

Njume, Collise; Afolayan, Anthony J; Ndip, Roland N

2011-04-01

Helicobacter pylori antibiotic resistance and other problems associated with combination therapy have generated a considerable interest in the search for alternative therapeutic agents. In order to identify novel sources of such agents, the antimicrobial activity of five solvent extracts of the stem bark of Sclerocarya birrea was investigated against 30 clinical strains of H. pylori and a reference strain NCTC 11638 using standard microbiological techniques. Metronidazole and amoxicillin were included in these experiments as positive control antibiotics. The active phytocomponents were detected by TLC and indirect bioautography. All the extracts exhibited anti-H. pylori activity with zone diameters of inhibition between 0 and 21 mm. The acetone and aqueous extracts showed potent anti-H. pylori activity with minimum inhibitory concentration (MIC(90)) values ranging from 0.06-2.50 mg/mL, whereas those for the control antibiotics ranged from 0.001-5.0 mg/mL. The acetone extract was highly bactericidal at 1.2 mg/mL with complete elimination of the organisms within 18 h. The activity of both acetone and aqueous extracts was better than metronidazole (p<0.05). Most of the active phytocomponents were located in the acetone extract; R(f)≤0.62 with >90% inhibition. These results demonstrate that the acetone and aqueous extracts of S. birrea may contain compounds with therapeutic activity; therefore, they may represent potential sources of new anti-H. pylori regimen. Copyright © 2011 IMSS. Published by Elsevier Inc. All rights reserved.

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

Ridge sowing of sunflower (Helianthus annuus L.) in a minimum till system improves the productivity, oil quality, and profitability on a sandy loam soil under an arid climate.

PubMed

Sher, Ahmad; Suleman, Muhammad; Qayyum, Abdul; Sattar, Abdul; Wasaya, Allah; Ijaz, Muhammad; Nawaz, Ahmad

2018-04-01

Sunflower (Helianthus annuus L.) is a major oilseed crop grown for its edible oil across the globe including Pakistan. In Pakistan, the production of edible oil is less than the required quantity; the situation is being worsened with the increasing population. Thus, there is dire need to grow those sunflower genotypes which perform better under a given set of agronomic practices. In this 2-year study, we compared four sunflower genotypes, viz., Armoni, Kundi, Sinji, and S-278 for their yield potential, oil contents, fatty acid composition, and profitability under three sowing methods, viz., bed sowing, line sowing, and ridge sowing and two tillage system, viz., plow till and minimum till. Among the sunflower genotypes, the genotype Armoni produced the highest plant height, number of leaves, head diameter, 1000-achene weight, and achene yield; the oil contents and oleic acid were the highest in genotype Sinji. Among the sowing methods, the highest number of leaves per plant, head diameter, number of achenes per head, achene yield, and oil contents were recorded in ridge sowing. Among the tillage systems, the highest head diameter 16. 2 cm, 1000-achene weight (57.2 g), achene yield (1.8 t ha -1 ), oil contents (35.2%), and oleic acid (15.2%) were recorded in minimum till sunflower. The highest net benefits and benefit to cost ratio were recorded in minimum till ridge sown Armoni genotype. In conclusion, the genotype Armoni should be grown on ridges to achieve the highest achene yield, oil contents, and net profitability.

Low-Current, Xenon Orificed Hollow Cathode Performance for In-Space Applications

NASA Technical Reports Server (NTRS)

Domonkos, Matthew T.; Patterson, Michael J.; Gallimore, Alec D.

2002-01-01

An experimental investigation of the operating characteristics of 3.2-mm diameter orificed hollow cathodes was conducted to examine low current and low flow rate operation. Cathode power was minimized with an orifice aspect ratio of approximately one and the use of an enclosed keeper. Cathode flow rate requirements were proportional to orifice diameter and the inverse of the orifice length. The minimum power consumption in diode mode was 10-W, and the minimum mass flow rate required for spot-mode emission was approximately 0.08-mg/s. Cathode temperature profiles were obtained using an imaging radiometer and conduction was found to be the dominant heat transfer mechanism from the cathode tube. Orifice plate temperatures were found to be weakly dependent upon the flow rate and strongly dependent upon the current.

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...

Annular ring zoom system using two positive axicons

NASA Astrophysics Data System (ADS)

Dickey, Fred M.; Conner, Jacob D.

2011-10-01

The production of an annular ring of light with a variable diameter has applications in laser material processing and machining, particle manipulation, and corneal surgery. This can readily be accomplished using a positive and negative axicon pair. However, negative axicons are very expensive and difficult to obtain with small diameters. In this paper, we present a design of an annular ring zoom system using two positive axicons. One axicon is placed a distance before a primary lens that is greater than some prescribed minimum, and the second axicon is placed after the primary lens. The position of the second axicon determines the ring diameter. The ring diameter can be zoomed from some maximum design size to a zero diameter ring (spot). Experimental results from a developmental system will be presented.

Estimation of merchantable bole volume and biomass above sawlog top in the National Forest inventory of the United States

Treesearch

Grant M. Domke; Christopher M. Oswalt; Christopher W. Woodall; Jeffery A. Turner

2013-01-01

Emerging markets for small-diameter roundwood along with a renewed interest in forest biomass for energy have created a need for estimates of merchantable biomass above the minimum sawlog top diameter for timber species in the national forest inventory of the United States. The Forest Inventory and Analysis (FIA) program of the USDA Forest Service recently adopted the...

Nonlifting wing-body combinations with certain geometric restraints having minimum wave drag at low supersonic speeds

NASA Technical Reports Server (NTRS)

Lomax, Harvard

1957-01-01

Several variational problems involving optimum wing and body combinations having minimum wave drag for different kinds of geometrical restraints are analyzed. Particular attention is paid to the effect on the wave drag of shortening the fuselage and, for slender axially symmetric bodies, the effect of fixing the fuselage diameter at several points or even of fixing whole portions of its shape.

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

Vertical variations in wood CO2 efflux for live emergent trees in a Bornean tropical rainforest.

PubMed

Katayama, Ayumi; Kume, Tomonori; Komatsu, Hikaru; Ohashi, Mizue; Matsumoto, Kazuho; Ichihashi, Ryuji; Kumagai, Tomo'omi; Otsuki, Kyoichi

2014-05-01

Difficult access to 40-m-tall emergent trees in tropical rainforests has resulted in a lack of data related to vertical variations in wood CO2 efflux, even though significant variations in wood CO2 efflux are an important source of errors when estimating whole-tree total wood CO2 efflux. This study aimed to clarify vertical variations in wood CO2 efflux for emergent trees and to document the impact of the variations on the whole-tree estimates of stem and branch CO2 efflux. First, we measured wood CO2 efflux and factors related to tree morphology and environment for seven live emergent trees of two dipterocarp species at four to seven heights of up to ∼ 40 m for each tree using ladders and a crane. No systematic tendencies in vertical variations were observed for all the trees. Wood CO2 efflux was not affected by stem and air temperature, stem diameter, stem height or stem growth. The ratios of wood CO2 efflux at the treetop to that at breast height were larger in emergent trees with relatively smaller diameters at breast height. Second, we compared whole-tree stem CO2 efflux estimates using vertical measurements with those based on solely breast height measurements. We found similar whole-tree stem CO2 efflux estimates regardless of the patterns of vertical variations in CO2 efflux because the surface area in the canopy, where wood CO2 efflux often differed from that at breast height, was very small compared with that at low stem heights, resulting in little effect of the vertical variations on the estimate. Additionally, whole-tree branch CO2 efflux estimates using measured wood CO2 efflux in the canopy were considerably different from those measured using only breast height measurements. Uncertainties in wood CO2 efflux in the canopy did not cause any bias in stem CO2 efflux scaling, but affected branch CO2 efflux. © The Author 2014. Published by Oxford University Press. All rights reserved.

Theoretical and empirical evidence for the relationship between stem diameter variations and the water status of mature temperate trees

NASA Astrophysics Data System (ADS)

Dietrich, Lars; Zweifel, Roman; Kahmen, Ansgar

2017-04-01

Assessing a trees' water status is essential to evaluate its water status during drought. In particular for mature trees it is extremely difficult to monitor the water status throughout the growing season because of the difficulty of canopy access. Daily variations of stem diameter (SDV) are discussed to provide a powerful alternative in measuring a trees' water status. SDV have been shown to incorporate both radial growth and the diurnal shrinkage and swelling of bark tissue, which is caused by daytime transpiration and nighttime refilling, respectively. During dry periods, bark tissue that is depleted in water cannot entirely refill at night resulting in a progressive overall shrinkage of the tree's stem diameter often called tree water deficit (TWD). Comprehensive comparisons of SDV-based values for TWD and reliable values of stem water potential are yet missing for mature trees. As such, TWD has not yet been fully established as a simple and continuous proxy for a trees' water status. Using a canopy crane situated in Northern Switzerland, we calculated TWD based on SDV for six Central European forest tree species during one moist (2014) and one exceptionally dry (2015) growing season and compared these values to the trees' branch water potential. We found a tight relationship between branch water potential and TWD in all six species. We further employed four different mathematical approaches to calculate TWD and tested what approach yielded the best relationship with water potential. Most approaches resulted in significant relationships (p < 0.001) for the different species. However, one TWD variable showed the highest explanatory power (R2) across the six species and both years (up to 86 % explained variation). Intriguingly, this variable does not account for radial growth during periods of shrinkage in its calculation indicating that plastic growth is impeded in such times. The relationship between TWD and stem water potential can best be explained by logistic functions. We propose that, based on such a function, TWD can be employed to estimate stem water potential of trees for an entire growing season. We conclude from our data that TWD is tightly correlated to the stem water potential of mature tree species and can, thus, be used to describe continuous seasonal variations in a tree's water status. Because of its relatively easy application and deployment, there is high potential for this method to play a major role in future investigations of tree water relations.

Correlations of catalytic combustor performance parameters

NASA Technical Reports Server (NTRS)

Bulzan, D. L.

1978-01-01

Correlations for combustion efficiency percentage drop and the minimum required adiabatic reaction temperature necessary to meet emissions goals of 13.6 g CO/kg fuel and 1.64 g HC/kg fuel are presented. Combustion efficiency was found to be a function of the cell density, cell circumference, reactor length, reference velocity, and adiabatic reaction temperature. The percentage pressure drop at an adiabatic reaction temperature of 1450 K was found to be proportional to the reference velocity to the 1.5 power and to the reactor length. It is inversely proportional to the pressure, cell hydraulic diameter, and fractional open area. The minimum required adiabatic reaction temperature was found to increase with reference velocity and decrease with cell circumference, cell density and reactor length. A catalyst factor was introduced into the correlations to account for differences between catalysts. Combustion efficiency, the percentage pressure drop, and the minimum required adiabatic reaction temperature were found to be a function of the catalyst factor. The data was from a 12 cm-diameter test rig with noble metal reactors using propane fuel at an inlet temperature of 800 K.

The minimum record time for PIV measurement in a vessel agitated by a Rushton turbine

NASA Astrophysics Data System (ADS)

Šulc, Radek; Ditl, Pavel; Fořt, Ivan; Jašíkova, Darina; Kotek, Michal; Kopecký, Václav; Kysela, Bohuš

In PIV studies published in the literature focusing on the investigation of the flow field in an agitated vessel the record time is ranging from the tenths and the units of seconds. The aim of this work was to determine minimum record time for PIV measurement in a vessel agitated by a Rushton turbine that is necessary to obtain relevant results of velocity field. The velocity fields were measured in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a Rushton turbine 133 mm in diameter using 2-D Time Resolved Particle Image Velocimetry in the impeller Reynolds number range from 50 000 to 189 000. This Re range secures the fully-developed turbulent flow of agitated liquid. Three liquids of different viscosities were used as the agitated liquid. On the basis of the analysis of the radial and axial components of the mean- and fluctuation velocities measured outside the impeller region it was found that dimensionless minimum record time is independent of impeller Reynolds number and is equalled N.tRmin = 103 ± 19.

Collector Size or Range Independence of SNR in Fixed-Focus Remote Raman Spectrometry.

PubMed

Hirschfeld, T

1974-07-01

When sensitivity allows, remote Raman spectrometers can be operated at a fixed focus with purely electronic (easily multiplexable) range gating. To keep the background small, the system etendue must be minimized. For a maximum range larger than the hyperfocal one, this is done by focusing the system at roughly twice the minimum range at which etendue matching is still required. Under these conditions the etendue varies as the fourth power of the collector diameter, causing the background shot noise to vary as its square. As the signal also varies with the same power, and background noise is usually limiting in this type instrument, the SNR becomes independent of the collector size. Below this minimum etendue-matched range, the transmission at the limiting aperture grows with the square of the range, canceling the inverse square loss of signal with range. The SNR is thus range independent below the minimum etendue matched range and collector size independent above it, with the location of transition being determined by the system etendue and collector diameter. The range of validity of these outrageousstatements is discussed.

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

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.

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.

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.

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.

Tree water status and growth of saplings and mature Norway spruce (Picea abies) at a dry distribution limit

PubMed Central

Oberhuber, Walter; Hammerle, Albin; Kofler, Werner

2015-01-01

We evaluated the size effect on stem water status and growth in Norway spruce (Picea abies (L.) Karst.) occurring at the edge of its natural range in a dry inner Alpine environment (750 m asl, Tyrol, Austria). Intra-annual dynamics of stem water deficit (ΔW), maximum daily shrinkage (MDS), and radial growth (RG) were compared among saplings (stem diameter/height: 2.2 cm/93 cm; n = 7) and mature adult trees (25 cm/12.7 m; n = 6) during 2014. ΔW, MDS, and RG were extracted from stem diameter variations, which were continuously recorded by automatic dendrometers and the influence of environmental drivers was evaluated by applying moving correlation analysis (MCA). Additionally, we used Morlet wavelet analysis to assess the differences in cyclic radial stem variations between saplings and mature trees. Results indicate that saplings and mature trees were experiencing water limitation throughout the growing season. However, saplings exhibited a more strained stem water status and higher sensitivity to environmental conditions than mature trees. Hence, the significantly lower radial increments in saplings (0.16 ± 0.03 mm) compared to mature trees (0.54 ± 0.14 mm) is related to more constrained water status in the former, affecting the rate and duration of RG. The wavelet analysis consistently revealed more distinct diurnal stem variations in saplings compared to mature trees. Intra-annual RG was most closely related to climate variables that influence transpiration, i.e., vapor pressure deficit, relative air humidity, and air temperature. MCA, however, showed pronounced instability of climate–growth relationships, which masked missing temporal or significant correlations when the entire study period (April–October) was considered. We conclude that an increase in evaporative demand will impair regeneration and long-term stability of drought-prone inner Alpine Norway spruce forests. PMID:26442019

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.

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.

ANTIBACTERIAL ACTIVITY OF DRACONTOMELON DAO EXTRACTS ON METHICILLIN-RESISTANT S. AUREUS (MRSA) AND E. COLI MULTIPLE DRUG RESISTANCE (MDR).

PubMed

Yuniati, Yuniati; Hasanah, Nurul; Ismail, Sjarif; Anitasari, Silvia; Paramita, Swandari

2018-01-01

Staphylococcus aureus , methicillin-resistant and Escherichia coli , multidrug-resistant included in the list of antibiotic-resistant priority pathogens from WHO. As multidrug-resistant bacteria problem is increasing, it is necessary to probe new sources for identifying antimicrobial compounds. Medicinal plants represent a rich source of antimicrobial agents. One of the potential plants for further examined as antibacterial is Dracontomelon dao (Blanco) Merr. & Rolfe. The present study designed to find the antibacterial activity of D. dao stem bark extracts on Methicillin-resistant S. aureus (MRSA) and E. coli Multiple Drug Resistance (MDR), followed by determined secondary metabolites with antibacterial activity and determined the value of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration). D. dao stem bark extracted using 60% ethanol. Disc diffusion test methods used to find the antibacterial activity, following by microdilution methods to find the value of MIC and MBC. Secondary metabolites with antibacterial activity determined by bioautography using TLC (thin layer chromatography) methods. D. dao stem bark extracts are sensitive to MSSA, MRSA and E.coli MDR bacteria. The inhibition zone is 16.0 mm in MSSA, 11.7 mm in MRSA and 10.7 mm in E. coli MDR. The entire MBC/MIC ratios for MSSA, MRSA and E.coli MDR is lower than 4. The ratio showed bactericidal effects of D. dao stem bark extracts. In TLC results, colorless bands found to be secondary metabolites with antibacterial activity. D. dao stem bark extracts are potential to develop as antibacterial agent especially against MRSA and E. coli MDR strain.

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

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. ...

[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.

Diameter modulation of vertically aligned single-walled carbon nanotubes.

PubMed

Xiang, Rong; Einarsson, Erik; Murakami, Yoichi; Shiomi, Junichiro; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2012-08-28

We demonstrate wide-range diameter modulation of vertically aligned single-walled carbon nanotubes (SWNTs) using a wet chemistry prepared catalyst. In order to ensure compatibility to electronic applications, the current minimum mean diameter of 2 nm for vertically aligned SWNTs is challenged. The mean diameter is decreased to about 1.4 nm by reducing Co catalyst concentrations to 1/100 or by increasing Mo catalyst concentrations by five times. We also propose a novel spectral analysis method that allows one to distinguish absorbance contributions from the upper, middle, and lower parts of a nanotube array. We use this method to quantitatively characterize the slight diameter change observed along the array height. On the basis of further investigation of the array and catalyst particles, we conclude that catalyst aggregation-rather than Ostwald ripening-dominates the growth of metal particles.

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.

Antioxidant and antibacterial activity of Thai medicinal plant (Capparis micracantha)

NASA Astrophysics Data System (ADS)

Laoprom, Nonglak; Sangprom, Araya; Chaisri, Patcharaporn

2018-04-01

This work aims to study the antioxidants capacity, Total phenolic content and antibacterial activity of Thai medicinal plant for the treatment of dermatitis-related inflammations, Capparis micracantha. Crude extract from stem of Thai medicinal plant was extracted with hexane, ethyl acetate, methanol and water. The antioxidant activities (IC50) was evaluated with 1,1-diphenyl-1-princylhydrazyl (DPPH) radical scavenging assay. Total phenolic content (TPC) was determined by using Folin-Ciocalteu method. Bacterial activities was tested with four human pathogenic bacteria; Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Stapylococcus epidermidis by using agar diffusion assay. Minimum Inhibition Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were also determined by broth dilution method. For antioxidant activity, the methanol fraction from stem extract showed the highest activity with an IC50 of 2.4 mg/ml. Water extraction was the high TPC with 10,136.9 mg GAE/g dry weight. Methanol and water extraction showed the remarkable inhibition of bacterial growth was shown against L. monocytogenes and S. aureus. In addition, ethyl acetate, methanol and water fraction from stem extract against S. epidermidis. The present finding suggests that the extract of C. micracantha could be used to discover bioactive natural products that may serve as pharmaceutical products.

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.

[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.

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...

The Role of Social Support on the Relationship between Gender and Career Progression in STEM Academia

DTIC Science & Technology

2015-03-26

sciences. According to the article, gender stereotyping was still an issue for women in STEM while treatment in other fields improved. The authors...Minimum Maximum Sum Mean Std. Deviation Gender DV (1= Male ) .00 1.00 50.00 .7692 .42460 Google Scholar Articles 0 192 2658 42.87 38.863 Years...Predictors: (Constant), Gender DV (1= Male ) Dependent Variable: Rank Results of analysis supported the hypothesis that gender is a predictor of the

7 CFR 457.173 - Florida Avocado crop insurance provisions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... a diameter of at least four inches. Crop year. A period beginning with the date insurance attaches... season after set out; and (2) Produced the minimum production per acre as specified in the Special...

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...

Corneal Epithelium Thickness Profile in 614 Normal Chinese Children Aged 7-15 Years Old.

PubMed

Ma, Yingyan; He, Xiangui; Zhu, Xiaofeng; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-03-23

The purpose of the study is to describe the values and distribution of corneal epithelium thickness (CET) in normal Chinese school-aged children, and to explore associated factors with CET. CET maps were measured by Fourier-domain optical coherence tomography (FD-OCT) in normal Chinese children aged 7 to 15 years old from two randomly selected schools in Shanghai, China. Children with normal intraocular pressure were further examined for cycloplegic autorefraction, corneal curvature radius (CCR) and axial length. Central (2-mm diameter area), para-central (2- to 5-mm diameter area), and peripheral (5- to 6-mm diameter area) CET in the superior, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal cornea; minimum, maximum, range, and standard deviation of CET within the 5-mm diameter area were recorded. The CET was thinner in the superior than in the inferior and was thinner in the temporal than in the nasal. The maximum CET was located in the inferior zone, and the minimum CET was in the superior zone. A thicker central CET was associated with male gender (p = 0.009) and older age (p = 0.037) but not with CCR (p = 0.061), axial length (p = 0.253), or refraction (p = 0.351) in the multiple regression analyses. CCR, age, and gender were correlated with para-central and peripheral CET.

Pulse height response of an optical particle counter to monodisperse aerosols

NASA Technical Reports Server (NTRS)

Wilmoth, R. G.; Grice, S. S.; Cuda, V.

1976-01-01

The pulse height response of a right angle scattering optical particle counter has been investigated using monodisperse aerosols of polystyrene latex spheres, di-octyl phthalate and methylene blue. The results confirm previous measurements for the variation of mean pulse height as a function of particle diameter and show good agreement with the relative response predicted by Mie scattering theory. Measured cumulative pulse height distributions were found to fit reasonably well to a log normal distribution with a minimum geometric standard deviation of about 1.4 for particle diameters greater than about 2 micrometers. The geometric standard deviation was found to increase significantly with decreasing particle diameter.

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.

Predictive variables for the biological behaviour of basal cell carcinoma of the face: relevance of morphometry of the nuclei.

PubMed

Appel, T; Bierhoff, E; Appel, K; von Lindern, J-J; Bergé, S; Niederhagen, B

2003-06-01

We did a morphometric analysis of 130 histological sections of basal cell carcinoma (BCC) of the face to find out whether morphometric variables in the structure of the nuclei of BCC cells could serve as predictors of the biological behaviour. We considered the following variables: maximum and minimum diameters, perimeter, nuclear area and five form factors that characterise and quantify the shape of a structure (axis ratio, shape factor, nuclear contour index, nuclear roundness and circumference ratio). We did a statistical analysis of primary and recurring tumours and four histology-based groups (multifocal superficial BCCs, nodular BCCs, sclerosing BCCs and miscellaneous forms) using a two-sided t test for independent samples. Multifocal superficial BCCs showed significantly smaller values for the directly measured variables (maximum and minimum diameters, perimeter and nuclear area). Morphometry could not distinguish between primary and recurring tumours.

Red blood cell generation by three-dimensional aggregate cultivation of late erythroblasts.

PubMed

Lee, EunMi; Han, So Yeon; Choi, Hye Sook; Chun, Bokhwan; Hwang, Byunghee; Baek, Eun Jung

2015-02-01

Stem cell-derived erythroid cells hold great potential for the treatment of blood-loss anemia and for erythropoiesis research; however, cultures using conventional flat plates or bioreactors have failed to show promising results. By mimicking the in vivo bone marrow (BM) environment in which most erythroid cells are physically aggregated, we show that a three-dimensional (3D) aggregate culture system facilitates erythroid cell maturation and red blood cell (RBC) production more effectively than two-dimensional high-density cell cultivation. Late erythroblasts (polychromatic or orthochromatic erythroblasts) were differentiated from cord blood CD34(+) cells over 15 days and then allowed to form tight aggregates at a minimum density of 1×10(7) cells/mL for 2-3 days. To scale up the cell culture and to make the media supply efficient throughout the cell aggregates, several macroporous microcarriers and porous scaffolds were applied to the 3D culture system. In comparison to control culture conditions, erythroid cells in 3D aggregates were significantly more differentiated toward RBCs with significantly reduced nuclear dysplasia. When 3D culture was performed inside macroporous microcarriers, the cell culture scale was increased and cells exhibited enhanced differentiation and enucleation. Microcarriers with a pore diameter of approximately 400 μm produced more mature cells than those with a smaller pore diameter. In addition, this aggregate culture method minimized the culture space and media volume required. In conclusion, a 3D aggregate culture system can be used to generate transfusable human erythrocytes at the terminal maturation stage, mimicking the in vivo BM microenvironment. Porous structures can efficiently maximize the culture scale, enabling large-scale production of RBCs. These results enhance our understanding of the importance of physical contact among late erythroblasts for their final maturation into RBCs.

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.

Fog : a review of the literature pertaining to highway problems and possible solutions.

DOT National Transportation Integrated Search

1972-01-01

1. Fogs are significant contributors to multiple car accidents that often result in fatalities. 2. Systems that adequately abate fogs or lighting systems that provide minimum visibility requirements have not evolved. 3. Most abatement techniques stem...

Fraudsters operate and officialdom turns a blind eye: a proposal for controlling stem cell therapy in China.

PubMed

Jiang, Li; Dong, Bing He

2016-09-01

Stem cell tourism-the flow of patients from home countries to destination countries to obtain stem cell treatment-is a growing business in China. Many concerns have been raised regarding fraudsters that operate unsafe stem cell therapies and an officialdom that turns a blind eye to the questionable technology. The Chinese regulatory approach to stem cell research is based on Guidelines and Administrative Measures, rather than legislation, and may have no binding force on certain institutions, such as military hospitals. There is no liability and traceability system and no visible set of penalties for non-compliance in the stem cell legal framework. In addition to the lack of safety and efficacy systems in the regulations, no specific expert authority has been established to monitor stem cell therapy to date. Recognizing the global nature of stem cell tourism, this article argues that resolving stem cell tourism issues may require not only the Chinese government but also an international mechanism for transparency and ethical oversight. A stringent set of international regulations that govern stem cell therapies can encourage China to improve stem cell regulation and enforcement to fulfill its obligations. Through an international consensus, a minimum standard for clinical stem cell research and a central enforcement system will be provided. As a result, rogue clinics that conduct unauthorized stem cell therapies can be penalized, and countries that are reluctant to implement the reconciled regulations should be sanctioned.

Numerical Optimization of the Position in Femoral Head of Proximal Locking Screws of Proximal Femoral Nail System; Biomechanical Study.

PubMed

Konya, Mehmet Nuri; Verim, Özgür

2017-09-29

Proximal femoral fracture rates are increasing due to osteoporosis and traffic accidents. Proximal femoral nails are routinely used in the treatment of these fractures in the proximal femur. To compare various combinations and to determine the ideal proximal lag screw position in pertrochanteric fractures (Arbeitsgemeinschaft für Osteosynthesefragen classification 31-A1) of the femur by using optimized finite element analysis. Biomechanical study. Computed tomography images of patients' right femurs were processed with Mimics. Afterwards a solid femur model was created with SolidWorks 2015 and transferred to ANSYS Workbench 16.0 for response surface optimization analysis which was carried out according to anterior-posterior (-10°0) and posterior-anterior directions of the femur neck significantly increased these stresses. The most suitable position of the proximal lag screw was confirmed as the middle of the femoral neck by using optimized finite element analysis.

Green synthesis of gold and silver nanoparticles from Cannabis sativa (industrial hemp) and their capacity for biofilm inhibition

PubMed Central

Singh, Priyanka; Pandit, Santosh; Garnæs, Jørgen; Tunjic, Sanja; Mokkapati, Venkata RSS; Sultan, Abida; Thygesen, Anders; Mackevica, Aiga; Mateiu, Ramona Valentina; Daugaard, Anders Egede; Baun, Anders; Mijakovic, Ivan

2018-01-01

Background Cannabis sativa (hemp) is a source of various biologically active compounds, for instance, cannabinoids, terpenes and phenolic compounds, which exhibit antibacterial, antifungal, anti-inflammatory and anticancer properties. With the purpose of expanding the auxiliary application of C. sativa in the field of bio-nanotechnology, we explored the plant for green and efficient synthesis of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). Methods and results The nanoparticles were synthesized by utilizing an aqueous extract of C. sativa stem separated into two different fractions (cortex and core [xylem part]) without any additional reducing, stabilizing and capping agents. In the synthesis of AuNPs using the cortex enriched in bast fibers, fiber-AuNPs (F-AuNPs) were achieved. When using the core part of the stem, which is enriched with phenolic compounds such as alkaloids and cannabinoids, core-AuNPs (C-AuNPs) and core-AgNPs (C-AgNPs) were formed. Synthesized nanoparticles were character-ized by UV–visible analysis, transmission electron microscopy, atomic force microscopy, dynamic light scattering, Fourier transform infrared, and matrix-assisted laser desorption/ionization time-of-flight. In addition, the stable nature of nanoparticles has been shown by thermogravimetric analysis and inductively coupled plasma mass spectrometry (ICP-MS). Finally, the AgNPs were explored for the inhibition of Pseudomonas aeruginosa and Escherichia coli biofilms. Conclusion The synthesized nanoparticles were crystalline with an average diameter between 12 and 18 nm for F-AuNPs and C-AuNPs and in the range of 20–40 nm for C-AgNPs. ICP-MS analysis revealed concentrations of synthesized nanoparticles as 0.7, 4.5 and 3.6 mg/mL for F-AuNPs, C-AuNPs and C-AgNPs, respectively. Fourier transform infrared spectroscopy revealed the presence of flavonoids, cannabinoids, terpenes and phenols on the nanoparticle surface, which could be responsible for reducing the salts to nanoparticles and further stabilizing them. In addition, the stable nature of synthesized nanoparticles has been shown by thermogravimetric analysis and ICP-MS. Finally, the AgNPs were explored for the inhibition of P. aeruginosa and E. coli biofilms. The nanoparticles exhibited minimum inhibitory concentration values of 6.25 and 5 µg/mL and minimum bactericidal concentration values of 12.5 and 25 µg/mL against P. aeruginosa and E. coli, respectively.

Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground Water Quality and Remediation Progress at DoD Sites for Perchlorate and Explosives Compounds

DTIC Science & Technology

2010-09-01

Regulatory Council LRL Laboratory reporting level LDPE Low-density polyethylene MDL Minimum detection limit MNA Monitored natural attenuation...consists of a tubular-shaped bag made of flexible low-density polyethylene ( LDPE ) (Vroblesky, 2001a, 2001b). The LDPE tube is heat-sealed on one end...be constructed from small- diameter LDPE tubing that fits into small-diameter wells. These polyethylene diffusion bag (PDB) samplers have been

Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground-Water Quality and Remediation Progress at DoD Site: Perchlorate and Ordnance Compounds

DTIC Science & Technology

2011-10-01

Regulatory Council LDPE low-density polyethylene MDL minimum detection limit NAVFAC ESC Naval Facilities Engineering Command Engineering Service...membrane sampler design consists of a tubular-shaped bag made of flexible low-density polyethylene ( LDPE ) (Vroblesky, 2001a, 2001b). The LDPE tube is...requirements, and can be constructed from small-diameter LDPE tubing that fits into small- 4 diameter wells. These polyethylene diffusion bag

Demonstration and Validation of a Regenerated Cellulose Dialysis Membrane Diffusion Sampler for Monitoring Ground-Water Quality and Remediation Progress at DoD Sites

DTIC Science & Technology

2010-04-01

LDPE low-density polyethylene LF low-flow purging LRL laboratory reporting level MDL minimum detection limit MNA monitored natural attenuation...shaped bag made of flexible low-density polyethylene ( LDPE ) (Vroblesky, 2001a, 2001b). The LDPE tube is heat-sealed on one end, filled with high...from small- diameter LDPE tubing that fits into small-diameter wells. These PDB samplers have been shown to be useful only for collection of VOCs

100 mm diameter rod laser amplifiers made of different Nd:glasses

NASA Astrophysics Data System (ADS)

Shaykin, A. A.; Kuzmin, A. A.; Shaikin, I. A.; Potemkin, A. K.; Arbuzov, V. I.; Hu, Lili; Wen, Lei; Khazanov, Е A.

2018-03-01

We measured the dependence of the weak signal gain of 100 mm diameter rod amplifiers on pump energy and transverse coordinates for four neodymium glass grades. The highest gain was obtained in N31-05 (China), and the highest radial gain uniformity in KGSS-0180 glass (Russia). The data obtained enable the optimal glass grade to be chosen for each specific problem by finding a compromise between maximum output energy and minimum distortion of beam profile.

Low loss fusion splicing polarization-maintaining photonic crystal fiber and conventional polarization-maintaining fiber

NASA Astrophysics Data System (ADS)

Zuoming, Sun; Ningfang, Song; Jing, Jin; Jingming, Song; Pan, Ma

2012-12-01

An efficient and simple method of fusion splicing of a Polarization-Maintaining Photonic Crystal Fiber (PM-PCF) and a conventional Polarization-Maintaining Fiber (PMF) with a low loss of 0.65 dB in experiment is reported. The minimum bending diameter of the joint can reach 2 cm. Theoretical calculation of the splicing loss based on mode field diameters (MFDs) mismatch of the two kinds of fibers is given. All parameters affected the splicing loss were studied.

Microdisk Injection Lasers for the 1.27-μm Spectral Range

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

Kryzhanovskaya, N. V.; Maximov, M. V.; Blokhin, S. A.

2016-03-15

Microdisk injection lasers on GaAs substrates, with a minimum diameter of 15 μm and an active region based on InAs/InGaAs quantum dots, are fabricated. The lasers operate in the continuous-wave mode at room temperature without external cooling. The lasing wavelength is around 1.27 μm at a minimum threshold current of 1.6 mA. The specific thermal resistance is estimated to be 5 × 10–3 °C cm{sup 2}/W.

49 CFR 230.99 - Tender truck axles.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Tenders Running Gear § 230.99 Tender truck axles. The minimum diameters of axles for various axle loads... wheel seat (in inches) Minimumdiameter of center (in inches) 50000 51/2 73/8 67/16 38000 5 63/4 57/8...

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%.

Determination of the manning coefficient from measured bed roughness in natural channels

USGS Publications Warehouse

Limerinos, John Thomas

1970-01-01

This report presents the results of a study to test the hypothesis that basic values of the Manning roughness coefficient of stream channels may be related to (1) some characteristic size of the streambed particles and to (2) the distribution of particle size. These two elements involving particle size can be combined into a single element by weighting characteristic particle sizes. The investigation was confined to channels with coarse bed material to avoid the complication of bed-form roughness that is associated with alluvial channels composed of fine bed material. Fifty current-meter measurements of discharge and appropriate field surveys were made at 11 sites on California streams for the purpose of computing the roughness coefficient, n, by the Manning formula. The test sites were selected to give a wide range in average size of bed material, and the discharge measurements and surveys were made at such times as to provide data covering a suitable range in stream depth. The sites selected were relatively free of the extraneous flow-retarding effects associated with irregular channel conformation and streambank vegetation. The characteristic bed-particle sizes used in the analyses were the 16,- 50,- and 84-percentile sizes as obtained from a cumulative frequency distribution of the diameters of randomly sampled surficial bed material. Separate distributions were computed for the minimum and intermediate values of the three diameters of a particle. The minimum diameters of the streambed particles were used in the study because a particle at rest on the bed invariably has its minimum diameter in the vertical position; this diameter is, therefore, the most representative measure of roughness height. The intermediate diameter was also studied because this is the diameter most easily measurable-either by sieve analysis or by photographic techniques--and--because it is the diameter that had been used in previous studies by other investigators. No significant difference in reliability was found between the results obtained using minimum diameters and those obtained using intermediate diameters. In analyzing the field data, the roughness parameter, n/R1/6 (where R is hydraulic radius), was related to relative smoothness, R/d (where d is a characteristic, or weighted characteristic, particle size). The parameter n/R1/6, rather than n, was used because it is directly proportional to the square root of the Darcy-Weisbach friction factor, f, which is more widely used in theoretical studies of hydraulic friction. If the transformation of n/R1/6 to vf is made, the relations obtained in this study are of a form that is identical with that of the theoretical friction equation obtained by several investigators and that derived from field data by Leopold and Wolman (1957). The constants in the equation vary, of course, with the characteristic particle size used. The relations best fitting the field data for this study were obtained by using either a characteristic particle diameter equal to the 84-percentile size (d84, the size equal to, or exceeding, that of 84 percent of the streambed particles), or a diameter obtained by weighting three characteristic particle sizes (dw, the size obtained by assigning a weight of 0.1 to d16 , a weight of 0.3 to d50 , and a weight of 0.6 to d84). The use of d84 alone gave slightly better results than the use of dw, and, in addition, the use of d84 alone is attractive from a standpoint of simplicity. It is difficult, however, to rationalize the use of d84 alone because of the implication that the distribution of sizes is irrelevant, and it matters not at all whether 84 percent of the bed material is sand or whether it is large cobbles, as long as 16 percent of the material is of greater size. Consequently, the author recommends the use of dw rather than d84 , although there was no unanimity of opinion on this recommendation among his colleagues who reviewed this paper. The reader is free to

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

Morphometric and mechanical characteristics of Equisetum hyemale stem enhance its vibration.

PubMed

Zajączkowska, Urszula; Kucharski, Stanisław; Nowak, Zdzisław; Grabowska, Kamila

2017-04-01

The order of the internodes, and their geometry and mechanical characteristics influence the capability of the Equisetum stem to vibrate, potentially stimulating spore liberation at the optimum stress setting along the stem. Equisetum hyemale L. plants represent a special example of cellular solid construction with mechanical stability achieved by a high second moment of area and relatively high resistance against local buckling. We proposed the hypothesis that the order of E. hyemale L. stem internodes, their geometry and mechanical characteristics influence the capability of the stem to vibrate, stimulating spore liberation at the minimum stress setting value along the stem. An analysis of apex vibration was done based on videos presenting the behavior of an Equisetum clump filmed in a wind tunnel and also as a result of excitation by bending the stem by 20°. We compared these data with the vibrations of stems of the same size but deprived of the three topmost internodes. Also, we created a finite element model (FEM), upon which we have based the 'natural' stem vibration as a copy of the real object, 'random' with reshuffled internodes and 'uniform', created as one tube with the characters averaged from all internodes. The natural internode arrangement influences the frequency and amplitude of the apex vibration, maintaining an equal stress distribution in the stem, which may influence the capability for efficient spore spreading.

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.

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

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.

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.

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

Flow and criticality in the open cycle gas core.

NASA Technical Reports Server (NTRS)

Kunze, J. F.; Lofthouse, J. H.

1971-01-01

A series of flowing gas experiments using air, argon, and freon has been conducted in Idaho. The purpose is to study methods of obtaining flow patterns which would create maximum possible system reactivity consistent with an acceptably low uranium to coolant-gas loss ratio. These have been conducted on both ?two-dimensional' and truly three-dimensional spherical configurations of diameters 18 to 42 inches. The larger diameter is that proposed for a minimum cost flowing gas critical experiment, and the size extremes make extrapolations to the large 6 and 8 foot diameter configurations more reliable. Results show that large enough inner gas (fuel) volume fractions can be achieved to attain criticality.

Using a slightly tapered optical fiber to attract and transport microparticles.

PubMed

Sheu, Fang-Wen; Wu, Hong-Yu; Chen, Sy-Hann

2010-03-15

We exploit a fiber puller to transform a telecom single-mode optical fiber with a 125 microm diameter into a symmetric and unbroken slightly tapered optical fiber with a 50 microm diameter at the minimum waist. When the laser light is launched into the optical fiber, we can observe that, due to the evanescent wave of the slightly tapered fiber, the nearby polystyrene microparticles with 10 microm diameters will be attracted onto the fiber surface and roll separately in the direction of light propagation. We have also simulated and compared the optical propulsion effects on the microparticles when the laser light is launched into a slightly tapered fiber and a heavily tapered (subwavelength) fiber, respectively.

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.

Chemical compositions and antibacterial activity of the leaf and stem oils of Piper porphyrophyllum (Lindl.) N.E. Br.

PubMed Central

Salleh, Wan Mohd Nuzul Hakimi Wan; Ahmad, Farediah; Sirat, Hasnah Mohd; Yen, Khong Heng

2012-01-01

The essential oils obtained by hydrodistillation from the fresh leaf and stem of Piper porphyrophyllum N.E. Br. were analyzed by GC and GC/MS. Thirty four constituents were identified in the leaf oil, while thirty eight constituents were identified in the stems oil. The most abundant components in the leaf oil included bicyclogermacrene (14.7 %), α-copaene (13.2 %) and β-phellandrene (9.5 %) while sabinene (15.5 %), bicyclogermacrene (12.3 %) and α-copaene (8.1 %) were the main constituents in the stem oil. The evaluation of antibacterial activity by using micro-dilution method revealed that both oils were moderately active against all the Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis) and Gram-negative bacteria (Pseudomonas aeruginosa, Pseudomonas putida and Escherichia coli) with minimum inhibitory concentration (MIC) values in the range 125-1000 µg/ml. PMID:27418915

Early follow-up of a custom non-fluted diaphyseal press-fit tumour prosthesis.

PubMed

O'Donnell, Patrick W; Griffin, Anthony M; Eward, William C; Sternheim, Amir; Wunder, Jay S; Ferguson, Peter C

2014-01-01

The objective of this study was to evaluate the early results of a custom non-fluted diaphyseal press-fit stem for use with the global modular replacement system (GMRS) tumour prosthesis and the early complications associated with this implant. A total of 53 patients (54 implants) were identified from a prospective database where a custom non-fluted diaphyseal press-fit stem was used as part of the reconstruction of the limb. All patients had a minimum of 22 months of follow-up. The rates of stem revision for any reason were calculated. The median follow-up was 36 months (range 22-85 months). Aseptic loosening was not observed in any patient. At early term follow-up, an uncemented non-fluted stem used with the GMRS tumour endoprosthesis provides a stable bone-prosthesis interface with no evidence of aseptic loosening.

Development and Use of Fluorescent Probes for Detection, Enumeration and Identification of Naturally-Occurring Marine Viruses.

DTIC Science & Technology

1992-05-31

Samples were preserved (27) stemmed from a loss in titer that occurred when viruses in 1% glutaraldehyde before application to carbon-coated were added to...counting a minimum of 100 VLPs from 5 random fields at a magnification of 10,000 x. For most applications counting a minimum of 20 fields containing at...biological applications , Vol. 4, Hayat, M.A., editor, Van Nostrom Reinhold, N.Y., 1974, pp 79-104. 15. Proctor, L.M., and Fuhrman, J.A., Viral mortality

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.

High resolution miniaturized stepper ultrasonic motor using differential composite motion.

PubMed

Chu, Xiangcheng; Xing, Zengping; Li, Longtu; Gui, Zhilun

2004-03-01

Experiments show that there is a limited minimum stepped angle in ultrasonic motors (USM). The research on the minimum angle of stepper USM with 15 mm in diameter and wobbling mode is being carried out. This paper presents a novel way to decrease the minimum stepped angle of USM based on the principle of differential composite motion (DCM), i.e. clockwise and counterclockwise rotation. The prototype was fabricated and experiments proved that this method is useful and also keeps a high torque for a large stepped angle. The stator of the prototype is steel, and rotor is fiberglass, antifriction material or steel. The prototype can operate well over 150 h with a 5 kHz wide frequency band. The minimum stepped angle is 46" using a coventional method while 12" using DCM method proposed in this paper.

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.

Area and volume ratios for prediction of visual outcome in idiopathic macular hole.

PubMed

Geng, Xing-Yun; Wu, Hui-Qun; Jiang, Jie-Hui; Jiang, Kui; Zhu, Jun; Xu, Yi; Dong, Jian-Cheng; Yan, Zhuang-Zhi

2017-01-01

To predict the visual outcome in patients undergoing macular hole surgery by two novel three-dimensional morphological parameters on optical coherence tomography (OCT): area ratio factor (ARF) and volume ratio factor (VRF). A clinical case series was conducted, including 54 eyes of 54 patients with an idiopathic macular hole (IMH). Each patient had an OCT examination before and after surgery. Morphological parameters of the macular hole, such as minimum diameter, base diameter, and height were measured. Then, the macular hole index (MHI), tractional hole index (THI), and hole form factor (HFF) were calculated. Meanwhile, novel postoperative macular hole (MH) factors, ARF and VRF were calculated by three-dimensional morphology. Bivariate correlations were performed to acquire asymptotic significance values between the steady best corrected visual acuity (BCVA) after surgery and 2D/3D arguments of MH by the Pearson method with two-tailed test. All significant factors were analyzed by the receiver operating characteristic (ROC) curve analysis of SPSS software which were responsible for vision recovery. ROC curves analyses were performed to further discuss the different parameters on the prediction of visual outcome. The mean and standard deviation values of patients' age, symptoms duration, and follow-up time were 64.8±8.9y (range: 28-81), 18.6±11.5d (range: 2-60), and 11.4±0.4mo (range: 6-24), respectively. Steady-post-BCVA analyzed with bivariate correlations was found to be significantly correlated with base diameter ( r =0.521, P <0.001), minimum diameter ( r =0.514, P <0.001), MHI ( r =-0.531, P <0.001), THI ( r =-0.386, P =0.004), HFF ( r =-0.508, P <0.001), and ARF ( r =-0.532, P <0.001). Other characteristic parameters such as age, duration of surgery, height, diameter hole index, and VRF were not statistically significant with steady-post-BCVA. According to area under the curve (AUC) values, values of ARF, MHI, HFF, minimum diameter, THI, and base diameter are 0.806, 0.772, 0.750, 0.705, 0.690, and 0.686, respectively. However, Steady-post-BCVA analysis with bivariate correlations for VRF was no statistical significance. Results of ROC curve analysis indicated that the MHI value, HFF, and ARF was greater than 0.427, 1.027 and 1.558 respectively which could correlate with better visual acuity. Compared with MHI and HFF, ARF could effectively express three-dimensional characteristics of macular hole and achieve better sensitivity and specificity. Thus, ARF could be the most effective parameter to predict the visual outcome in macular hole surgery.

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.

Monitoring of Freezing Dynamics in Trees: A Simple Phase Shift Causes Complexity1[OPEN

PubMed Central

Charra-Vaskou, Katline

2017-01-01

During winter, trees have to cope with harsh conditions, including extreme freeze-thaw stress. This study focused on ice nucleation and propagation, related water shifts and xylem cavitation, as well as cell damage and was based on in situ monitoring of xylem (thermocouples) and surface temperatures (infrared imaging), ultrasonic emissions, and dendrometer analysis. Field experiments during late winter on Picea abies growing at the alpine timberline revealed three distinct freezing patterns: (1) from the top of the tree toward the base, (2) from thin branches toward the main stem’s top and base, and (3) from the base toward the top. Infrared imaging showed freezing within branches from their base toward distal parts. Such complex freezing causes dynamic and heterogenous patterns in water potential and probably in cavitation. This study highlights the interaction between environmental conditions upon freezing and thawing and demonstrates the enormous complexity of freezing processes in trees. Diameter shrinkage, which indicated water fluxes within the stem, and acoustic emission analysis, which indicated cavitation events near the ice front upon freezing, were both related to minimum temperature and, upon thawing, related to vapor pressure deficit and soil temperature. These complex patterns, emphasizing the common mechanisms between frost and drought stress, shed new light on winter tree physiology. PMID:28242655

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.

Strand displacement amplification for ultrasensitive detection of human pluripotent stem cells.

PubMed

Wu, Wei; Mao, Yiping; Zhao, Shiming; Lu, Xuewen; Liang, Xingguo; Zeng, Lingwen

2015-06-30

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), provide a powerful model system for studies of cellular identity and early mammalian development, which hold great promise for regenerative medicine. It is necessary to develop a convenient method to discriminate hPSCs from other cells in clinics and basic research. Herein, a simple and reliable biosensor for stem cell detection was established. In this biosensor system, stage-specific embryonic antigen-3 (SSEA-3) and stage-specific embryonic antigen-4 (SSEA-4) were used to mark human pluripotent stem cells (hPSCs). Antibody specific for SSEA-3 was coated onto magnetic beads for hPSCs enrichment, and antibody specific for SSEA-4 was conjugated with carboxyl-modified tDNA sequence which was used as template for strand displacement amplification (SDA). The amplified single strand DNA (ssDNA) was detected with a lateral flow biosensor (LFB). This biosensor is capable of detecting a minimum of 19 human embryonic stem cells by a strip reader and 100 human embryonic stem cells by the naked eye within 80min. This approach has also shown excellent specificity to distinguish hPSCs from other types of cells, showing that it is promising for specific and handy detection of human pluripotent stem cells. Copyright © 2015 Elsevier B.V. All rights reserved.

A stocking guide for eastern white pine

Treesearch

James S. Philbrook; James P. Barrett; William B. Leak

1973-01-01

A stocking chart for eastern white pine is presented and described. The chart shows basal areas and numbers of trees by mean stand diameter, representing the upper limit in stocking for practical management (A curve) and minimum stocking for full site utilization (B curve).

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

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.

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.

Gas-driven pump for ground-water samples

USGS Publications Warehouse

Signor, Donald C.

1978-01-01

Observation wells installed for artificial-recharge research and other wells used in different ground-water programs are frequently cased with small-diameter steel pipe. To obtain samples from these small-diameter wells in order to monitor water quality, and to calibrate solute-transport models, a small-diameter pump with unique operating characteristics is required that causes a minimum alternation of samples during field sampling. A small-diameter gas-driven pump was designed and built to obtain water samples from wells of two-inch diameter or larger. The pump is a double-piston type with the following characteristics: (1) The water sample is isolated from the operating gas, (2) no source of electricity is ncessary, (3) operation is continuous, (4) use of compressed gas is efficient, and (5) operation is reliable over extended periods of time. Principles of operation, actual operation techniques, gas-use analyses and operating experience are described. Complete working drawings and a component list are included. Recent modifications and pump construction for high-pressure applications also are described. (Woodard-USGS)

Design and fabrication of a boron reinforced intertank skirt

NASA Technical Reports Server (NTRS)

Henshaw, J.; Roy, P. A.; Pylypetz, P.

1974-01-01

Analytical and experimental studies were performed to evaluate the structural efficiency of a boron reinforced shell, where the medium of reinforcement consists of hollow aluminum extrusions infiltrated with boron epoxy. Studies were completed for the design of a one-half scale minimum weight shell using boron reinforced stringers and boron reinforced rings. Parametric and iterative studies were completed for the design of minimum weight stringers, rings, shells without rings and shells with rings. Computer studies were completed for the final evaluation of a minimum weight shell using highly buckled minimum gage skin. The detail design is described of a practical minimum weight test shell which demonstrates a weight savings of 30% as compared to an all aluminum longitudinal stiffened shell. Sub-element tests were conducted on representative segments of the compression surface at maximum stress and also on segments of the load transfer joint. A 10 foot long, 77 inch diameter shell was fabricated from the design and delivered for further testing.

Sex determination from the radius and ulna in a modern South African sample.

PubMed

Barrier, I L O; L'Abbé, E N

2008-07-18

With a large number of unidentified skeletal remains found in South Africa, the development of population specific osteometric standards is imperative. Forensic anthropologists need to have access to a variety of techniques to establish accurate demographic profiles from complete, fragmentary and/or commingled remains. No research has been done on the forearm of African samples, even though these bones have been shown to exhibit sexual dimorphism. The purpose of this paper is to develop discriminant function formulae to determine sex from the radius and ulna in a South African population. The sample consisted of 200 male and 200 female skeletons from the Pretoria Bone (University of Pretoria) and Raymond A. Dart (Witwatersrand University) collections. Sixteen standard anthropometric measurements were taken from the radius (9) and ulna (7) and subjected to stepwise and direct discriminant function analysis. Distal breadth, minimum mid-shaft diameter and maximum head diameter were the best discriminators of sex for the radius, while minimum mid-shaft diameter and olecranon breadth were selected for the ulna. Classification accuracy for the forearm ranged from 76 to 86%. The radius and ulna can be considered moderate discriminators for determining sex in a South African group. However, it is advised that these formulae are used in conjunction with additional methods to determine sex.

Dust Cloud Modeling and Propagation Effects for Radar and Communications Codes

DTIC Science & Technology

1978-11-01

particles can be described by a power law probabi 1it Y d i st r i ut i on with a power exponent of 4. Four is a typical value for dust particlIs from...loose unconsolidated soils such as desert alluviun, blust ,eera ted from a nuclear cratering explosion in rock and cohes ive soil s haN pO,,e r exponent ...da p = power law exponent amin = minimum particle diameter in the distribution (cm) a = maximum particle diameter in the distribution (cm).max The log

Study of solid rocket motors for a space shuttle booster. Appendix C: Recovery and reuse 120-inch diameter solid rocket motor boosters

NASA Technical Reports Server (NTRS)

1972-01-01

A baseline for a space shuttle configuration utilizing four parallel-burn 120-in. diameter SRMS is presented. Topics discussed include parachute system sequence, recovery system development profile, parachute container, and segment and closure recovery operations. A cost analysis for recovery of the SRM stage is presented. It is concluded that from the standpoint of minimum cost and development, parachutes are the best means of achieving SRM recovery. Major SRM components can be reused safely.

Applications Of Measurement Techniques To Develop Small-Diameter, Undersea Fiber Optic Cables

NASA Astrophysics Data System (ADS)

Kamikawa, Neil T.; Nakagawa, Arthur T.

1984-12-01

Attenuation, strain, and optical time domain reflectometer (OTDR) measurement techniques were applied successfully in the development of a minimum-diameter, electro-optic sea floor cable. Temperature and pressure models for excess attenuation in polymer coated, graded-index fibers were investigated analytically and experimentally using these techniques in the laboratory. The results were used to select a suitable fiber for the cable. Measurements also were performed on these cables during predeployment and sea-trial testing to verify laboratory results. Application of the measurement techniques and results are summarized in this paper.

Steiner trees and spanning trees in six-pin soap films

NASA Astrophysics Data System (ADS)

Dutta, Prasun; Khastgir, S. Pratik; Roy, Anushree

2010-02-01

The problem of finding minimum (local as well as absolute) path lengths joining given points (or terminals) on a plane is known as the Steiner problem. The Steiner problem arises in finding the minimum total road length joining several towns and cities. We study the Steiner tree problem using six-pin soap films. Experimentally, we observe spanning trees as well as Steiner trees partly by varying the pin diameter. We propose a possibly exact expression for the length of a spanning tree or a Steiner tree, which fails mysteriously in certain cases.

Testing and Improving Theories of Radiative Transfer for Determining the Mineralogy of Planetary Surfaces

NASA Astrophysics Data System (ADS)

Gudmundsson, E.; Ehlmann, B. L.; Mustard, J. F.; Hiroi, T.; Poulet, F.

2012-12-01

Two radiative transfer theories, the Hapke and Shkuratov models, have been used to estimate the mineralogic composition of laboratory mixtures of anhydrous mafic minerals from reflected near-infrared light, accurately modeling abundances to within 10%. For this project, we tested the efficacy of the Hapke model for determining the composition of mixtures (weight fraction, particle diameter) containing hydrous minerals, including phyllosilicates. Modal mineral abundances for some binary mixtures were modeled to +/-10% of actual values, but other mixtures showed higher inaccuracies (up to 25%). Consequently, a sensitivity analysis of selected input and model parameters was performed. We first examined the shape of the model's error function (RMS error between modeled and measured spectra) over a large range of endmember weight fractions and particle diameters and found that there was a single global minimum for each mixture (rather than local minima). The minimum was sensitive to modeled particle diameter but comparatively insensitive to modeled endmember weight fraction. Derivation of the endmembers' k optical constant spectra using the Hapke model showed differences with the Shkuratov-derived optical constants originally used. Model runs with different sets of optical constants suggest that slight differences in the optical constants used significantly affect the accuracy of model predictions. Even for mixtures where abundance was modeled correctly, particle diameter agreed inconsistently with sieved particle sizes and varied greatly for individual mix within suite. Particle diameter was highly sensitive to the optical constants, possibly indicating that changes in modeled path length (proportional to particle diameter) compensate for changes in the k optical constant. Alternatively, it may not be appropriate to model path length and particle diameter with the same proportionality for all materials. Across mixtures, RMS error increased in proportion to the fraction of the darker endmember. Analyses are ongoing and further studies will investigate the effect of sample hydration, permitted variability in particle size, assumed photometric functions and use of different wavelength ranges on model results. Such studies will advance understanding of how to best apply radiative transfer modeling to geologically complex planetary surfaces. Corresponding authors: eyjolfur88@gmail.com, ehlmann@caltech.edu

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

7 CFR 51.2836 - Size classifications.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 2 2012-01-01 2012-01-01 false Size classifications. 51.2836 Section 51.2836...) Size Classifications § 51.2836 Size classifications. The size of onions may be specified in accordance with one of the following classifications. Size designation Minimum diameter Inches Millimeters Maximum...

7 CFR 51.2836 - Size classifications.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Size classifications. 51.2836 Section 51.2836...) Size Classifications § 51.2836 Size classifications. The size of onions may be specified in accordance with one of the following classifications. Size designation Minimum diameter Inches Millimeters Maximum...

7 CFR 51.2836 - Size classifications.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 2 2011-01-01 2011-01-01 false Size classifications. 51.2836 Section 51.2836...) Size Classifications § 51.2836 Size classifications. The size of onions may be specified in accordance with one of the following classifications. Size designation Minimum diameter Inches Millimeters Maximum...

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....

The Atacama Compact Array: An Overview

NASA Astrophysics Data System (ADS)

Iguchi, S.; Wilson, T. L.

2010-01-01

When completed, ALMA will comprise a 12-meter diameter antennas array (12-m Array) of a minimum of fifty antennas, and the ACA (Atacama Compact Array), composed of four 12-meter diameter antennas and twelve 7-meter diameter antennas. Out of the fifty antennas of the 12-m Array, one-half are provided by the North American partners of ALMA, the other half by the European partners. The sixteen antennas that will comprise the ACA are provided by the East Asian Partners of ALMA. In the last issue of the ALMA Science Newsletter, we outlined the testing of the prototype ALMA 12-meter diameter antennas and the procurement process for these antennas. In that article, only a short account was given of the antennas for the Atacama Compact Array (ACA). In the following we give an overview of the ACA, starting with an introduction to imaging using interferometers.

Variable diameter CO₂ laser ring-cutting system adapted to a zoom microscope for applications on polymer tapes.

PubMed

Förster, Erik; Bohnert, Patrick; Kraus, Matthias; Kilper, Roland; Müller, Ute; Buchmann, Martin; Brunner, Robert

2016-11-20

This paper presents the conception and implementation of a variable diameter ring-cutting system for a CO₂ laser with a working wavelength of 10.6 μm. The laser-cutting system is adapted to an observation zoom microscope for combined use and is applicable for the extraction of small circular areas from polymer films, such as forensic adhesive tapes in a single shot. As an important characteristic for our application, the variable diameter ring-cutting system provides telecentricity in the target area. Ring diameters are continuously tunable between 500 μm and 2 mm. A minimum width of less than 20 μm was found for the ring profile edge. The basic characteristics of the system, including telecentricity, were experimentally evaluated and demonstrated by cutting experiments on different polymer tapes and further exemplary samples.

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.