Semantic Segmentation of Forest Stands of Pure Species as a Global Optimization Problem

NASA Astrophysics Data System (ADS)

Dechesne, C.; Mallet, C.; Le Bris, A.; Gouet-Brunet, V.

2017-05-01

Forest stand delineation is a fundamental task for forest management purposes, that is still mainly manually performed through visual inspection of geospatial (very) high spatial resolution images. Stand detection has been barely addressed in the literature which has mainly focused, in forested environments, on individual tree extraction and tree species classification. From a methodological point of view, stand detection can be considered as a semantic segmentation problem. It offers two advantages. First, one can retrieve the dominant tree species per segment. Secondly, one can benefit from existing low-level tree species label maps from the literature as a basis for high-level object extraction. Thus, the semantic segmentation issue becomes a regularization issue in a weakly structured environment and can be formulated in an energetical framework. This papers aims at investigating which regularization strategies of the literature are the most adapted to delineate and classify forest stands of pure species. Both airborne lidar point clouds and multispectral very high spatial resolution images are integrated for that purpose. The local methods (such as filtering and probabilistic relaxation) are not adapted for such problem since the increase of the classification accuracy is below 5%. The global methods, based on an energy model, tend to be more efficient with an accuracy gain up to 15%. The segmentation results using such models have an accuracy ranging from 96% to 99%.

Twenty-four years after theYellowstone Fires: Are postfire lodgepole pine stands converging in structure and function?

PubMed

Turner, Monica G; Whitby, Timothy G; Tinker, Daniel B; Romme, William H

2016-05-01

Disturbance and succession have long been of interest in ecology, but how landscape patterns of ecosystem structure and function evolve following large disturbances is poorly understood. After nearly 25 years, lodgepole pine (Pinus contorta var. latifolia) forests that regenerated after the 1988 Yellowstone Fires (Wyoming, USA) offer a prime opportunity to track the fate of disturbance-created heterogeneity in stand structure and function in a wilderness setting. In 2012, we resampled 72 permanent plots to ask (1) How have postfire stand structure and function changed between 11 and 24 yr postfire, and what variables explain these patterns and changes? (2) How has landscape-level (among-stand) variability in postfire stand structure and function changed between 11 and 24 yr postfire? We expected to see evidence of convergence beginning to emerge, but also that initial postfire stem density would still determine trajectories of biomass accumulation. After 24 yr, postfire lodgepole pine density remained very high (mean = 21,738 stems/ha, range = 0-344,067 stems/ha). Stem density increased in most plots between 11 and 24 yr postfire, but declined sharply where 11-yr-postfire stem density was > 72,000 stems/ha. Stems were small in high-density stands, but stand-level lodgepole pine leaf area, foliage biomass, and live aboveground biomass increased over time and with increasing stem density. After 24 yr, mean annual lodgepole pine aboveground net primary production (ANPP) was high (mean = 5 Mg · ha⁻¹ · yr⁻¹, range = 0-16.5 Mg · ha⁻¹ · yr⁻¹). Among stands, lodgepole pine ANPP increased with stem density, which explained 69% of the variation; another 8% of the variation was explained by environmental covariates. Early patterns of postfire lodgepole pine regeneration, which were contingent on prefire serotiny and fire severity, remained the dominant driver of stand structure and function. We observed mechanisms that would lead to convergence in stem density (structure) over time, but it was landscape variation in functional variables that declined substantially. Stand structure and function have not converged across the burned landscape, but our evidence suggests function will converge sooner than structure.

Last interglacial (MIS5e) sea-levels and uplift along the north-east Gulf of Aqaba

NASA Astrophysics Data System (ADS)

BAR (KOHN), N.; Stein, M.; Agnon, A.; Yehudai, M.; Lazar, B.; Shaked, Y.

2014-12-01

An uplifted flight of coral reef terraces, extending along the north-east margin of the Gulf of Aqaba (GOA), provides evidence for uplift rates and sea level high stands. GOA fills a narrow and deep tectonic depression lying along the southern sector of the Dead Sea Transform where it meets the Red Sea. This special configuration of the GOA and its latitude turn it into a dependable paleo-sea level monitor, sensitive only to global eustatic changes and local tectonic movements. A sequence of five uplifted coral reef terraces were mapped and characterized on basis of morphology and reef-facies, and their elevation above the present sea level was determined. The fossil reefs studied comprise fringing reefs, some with clear reef-structure that includes a reef flat and a shallow back lagoon. Most outcrops in the study area represent a transgressive sequence in which, during its highest stand, formed fringing reef terraces. We use U-Th ages of fossil corals samples found in growth position at various terraces. Corals from three uplifted reef terraces, R1, R2, and R3 were dated to the last interglacial period particularly to marine isotope stage (MIS) 5e. These ages were achieved from mainly calcitic corals (recrystallized in a freshwater phreatic environment). A few ages were derived from aragonite corals. The three terraces represent three sub-stages within MIS5e: R3 formed during a short standstill at ~130 ka BP; R2 formed during a long and steady standstill between ~128 to ~121 ka BP; and R1 represents a short standstill at ~117 ka BP. Assuming that terrace reef flats represent past sea level high stands, we calculated the coast average uplift rate and constrained the original terraces elevations. The reconstructed eustatic sea level variation during MIS 5e at GOA resembles observations from reef terraces in other locations. Combined, all indicate a significant sea-level rise from the MIS 6 low stand at ~134-130 ka and followed by a long and stable sea level high stand between ~128 to ~121 ka, representing a major reef building period. The long and stable sea level was followed by additional sea-level rise at ~118-116 ka that transgressed over the "stable reefs".

Distributing stand inventory data and maps over a wide area network

Treesearch

Thomas E. Burk

2000-01-01

High-speed networks connecting multiple levels of management are becoming commonplace among forest resources organizations. Such networks can be used to deliver timely spatial and aspatial data relevant to the management of stands to field personnel. A network infrastructure allows maintenance of cost-effective, centralized databases with the potential for updating by...

Estimation of the stand ages of tropical secondary forests after shifting cultivation based on the combination of WorldView-2 and time-series Landsat images

NASA Astrophysics Data System (ADS)

Fujiki, Shogoro; Okada, Kei-ichi; Nishio, Shogo; Kitayama, Kanehiro

2016-09-01

We developed a new method to estimate stand ages of secondary vegetation in the Bornean montane zone, where local people conduct traditional shifting cultivation and protected areas are surrounded by patches of recovering secondary vegetation of various ages. Identifying stand ages at the landscape level is critical to improve conservation policies. We combined a high-resolution satellite image (WorldView-2) with time-series Landsat images. We extracted stand ages (the time elapsed since the most recent slash and burn) from a change-detection analysis with Landsat time-series images and superimposed the derived stand ages on the segments classified by object-based image analysis using WorldView-2. We regarded stand ages as a response variable, and object-based metrics as independent variables, to develop regression models that explain stand ages. Subsequently, we classified the vegetation of the target area into six age units and one rubber plantation unit (1-3 yr, 3-5 yr, 5-7 yr, 7-30 yr, 30-50 yr, >50 yr and 'rubber plantation') using regression models and linear discriminant analyses. Validation demonstrated an accuracy of 84.3%. Our approach is particularly effective in classifying highly dynamic pioneer vegetation younger than 7 years into 2-yr intervals, suggesting that rapid changes in vegetation canopies can be detected with high accuracy. The combination of a spectral time-series analysis and object-based metrics based on high-resolution imagery enabled the classification of dynamic vegetation under intensive shifting cultivation and yielded an informative land cover map based on stand ages.

Semantic segmentation of forest stands of pure species combining airborne lidar data and very high resolution multispectral imagery

NASA Astrophysics Data System (ADS)

Dechesne, Clément; Mallet, Clément; Le Bris, Arnaud; Gouet-Brunet, Valérie

2017-04-01

Forest stands are the basic units for forest inventory and mapping. Stands are defined as large forested areas (e.g., ⩾ 2 ha) of homogeneous tree species composition and age. Their accurate delineation is usually performed by human operators through visual analysis of very high resolution (VHR) infra-red images. This task is tedious, highly time consuming, and should be automated for scalability and efficient updating purposes. In this paper, a method based on the fusion of airborne lidar data and VHR multispectral images is proposed for the automatic delineation of forest stands containing one dominant species (purity superior to 75%). This is the key preliminary task for forest land-cover database update. The multispectral images give information about the tree species whereas 3D lidar point clouds provide geometric information on the trees and allow their individual extraction. Multi-modal features are computed, both at pixel and object levels: the objects are individual trees extracted from lidar data. A supervised classification is then performed at the object level in order to coarsely discriminate the existing tree species in each area of interest. The classification results are further processed to obtain homogeneous areas with smooth borders by employing an energy minimum framework, where additional constraints are joined to form the energy function. The experimental results show that the proposed method provides very satisfactory results both in terms of stand labeling and delineation (overall accuracy ranges between 84 % and 99 %).

Sit-to-Stand Movement in Children with Cerebral Palsy: A Critical Review

ERIC Educational Resources Information Center

dos Santos, Adriana Neves; Pavao, Silvia Leticia; Rocha, Nelci Adriana Cicuto Ferreira

2011-01-01

Sit-to-stand (STS) movement is widely performed in daily life and an important pre requisite for acquisition of functional abilities. However, STS is a biomechanical demanding task which requires high levels of neuromuscular coordination, muscle strength and postural control. As children with cerebral palsy (CP) exhibit a series of impairments in…

Modeling the size-density relationship in direct-seeded slash pine stands

Treesearch

Quang V. Cao; Thomas J. Dean; V. Clark Baldwin

2000-01-01

The relationship between quadratic mean diameter and tree density appeared curvilinear on a log–log scale, based on data from direct-seeded slash pine (Pinus elliotti var. elliotti Engelm.) stands. The self-thinning trajectory followed a straight line for high tree density levels and then turned away from this line as tree density...

Patterns of NPP, GPP, respiration, and NEP during boreal forest succession

USGS Publications Warehouse

Goulden, M.L.; Mcmillan, A.M.S.; Winston, G.C.; Rocha, A.V.; Manies, K.L.; Harden, J.W.; Bond-Lamberty, B. P.

2011-01-01

We combined year-round eddy covariance with biometry and biomass harvests along a chronosequence of boreal forest stands that were 1, 6, 15, 23, 40, 74, and 154 years old to understand how ecosystem production and carbon stocks change during recovery from stand-replacing crown fire. Live biomass (Clive) was low in the 1 and 6 year old stands, and increased following a logistic pattern to high levels in the 74 and 154year old stands. Carbon stocks in the forest floor (Cforest floor) and coarse woody debris (CCWD) were comparatively high in the 1year old stand, reduced in the 6 through 40year old stands, and highest in the 74 and 154year old stands. Total net primary production (TNPP) was reduced in the 1 and 6year old stands, highest in the 23 through 74year old stands and somewhat reduced in the 154year old stand. The NPP decline at the 154year old stand was related to increased autotrophic respiration rather than decreased gross primary production (GPP). Net ecosystem production (NEP), calculated by integrated eddy covariance, indicated the 1 and 6 year old stands were losing carbon, the 15year old stand was gaining a small amount of carbon, the 23 and 74year old stands were gaining considerable carbon, and the 40 and 154year old stands were gaining modest amounts of carbon. The recovery from fire was rapid; a linear fit through the NEP observations at the 6 and 15year old stands indicated the transition from carbon source to sink occurred within 11-12 years. The NEP decline at the 154year old stand appears related to increased losses from Clive by tree mortality and possibly from Cforest floor by decomposition. Our findings support the idea that NPP, carbon production efficiency (NPP/GPP), NEP, and carbon storage efficiency (NEP/TNPP) all decrease in old boreal stands. ?? 2010 Blackwell Publishing Ltd.

Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG

NASA Astrophysics Data System (ADS)

Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

2016-01-01

Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG.

PubMed

Lyu, Lu; Niu, Dongmei; Xie, Haipeng; Cao, Ningtong; Zhang, Hong; Zhang, Yuhe; Liu, Peng; Gao, Yongli

2016-01-21

Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecular tilt angle about the substrate normal with the increasing film thickness.

Object-based class modelling for multi-scale riparian forest habitat mapping

NASA Astrophysics Data System (ADS)

Strasser, Thomas; Lang, Stefan

2015-05-01

Object-based class modelling allows for mapping complex, hierarchical habitat systems. The riparian zone, including forests, represents such a complex ecosystem. Forests within riparian zones are biologically high productive and characterized by a rich biodiversity; thus considered of high community interest with an imperative to be protected and regularly monitored. Satellite earth observation (EO) provides tools for capturing the current state of forest habitats such as forest composition including intermixture of non-native tree species. Here we present a semi-automated object based image analysis (OBIA) approach for the mapping of riparian forests by applying class modelling of habitats based on the European Nature Information System (EUNIS) habitat classifications and the European Habitats Directive (HabDir) Annex 1. A very high resolution (VHR) WorldView-2 satellite image provided the required spatial and spectral details for a multi-scale image segmentation and rule-base composition to generate a six-level hierarchical representation of riparian forest habitats. Thereby habitats were hierarchically represented within an image object hierarchy as forest stands, stands of homogenous tree species and single trees represented by sunlit tree crowns. 522 EUNIS level 3 (EUNIS-3) habitat patches with a mean patch size (MPS) of 12,349.64 m2 were modelled from 938 forest stand patches (MPS = 6868.20 m2) and 43,742 tree stand patches (MPS = 140.79 m2). The delineation quality of the modelled EUNIS-3 habitats (focal level) was quantitatively assessed to an expert-based visual interpretation showing a mean deviation of 11.71%.

Thorium-230 ages of corals and duration of the last interglacial sea-level high stand on Oahu, Hawaii

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

Szabo, B.J.; Ludwig, K.R.; Muhs, D.R.

1994-10-07

Thorium-230 ages of emergent marine deposits on Oahu, Hawaii, have a uniform distribution of ages from {approximately}114,000 to {approximately}131,000 years, indicating a duration for the last interglacial sea-level high stand of {approximately}17,000 years, in contrast to a duration of {approximately}8000 years inferred from the orbitally tuned marine oxygen isotope record. Sea level on Oahu rose to {>=}1 to 2 meters higher than present by 131,000 years ago or {approximately}6000 years earlier than inferred from the marine record. Although the latter record suggests a shift back to glacial conditions beginning at {approximately}119,000 years ago, the Oahu coral ages indicate a nearmore » present sea level until {approximately}114,000 years ago.« less

Postural strategy and trunk muscle activation during prolonged standing in chronic low back pain patients.

PubMed

Ringheim, Inge; Austein, Helene; Indahl, Aage; Roeleveld, Karin

2015-10-01

Prolonged standing has been associated with development and aggravation of low back pain (LBP). However, the underlying mechanisms are not well known. The aim of the present study was to investigate postural control and muscle activation during and as a result of prolonged standing in chronic LBP (cLBP) patients compared to healthy controls (HCs). Body weight shifts and trunk and hip muscle activity was measured during 15 min standing. Prior and after the standing trial, strength, postural sway, reposition error (RE), flexion relaxation ratio (FRR), and pain were assessed and after the prolonged standing, ratings of perceived exertion. During prolonged standing, the cLBP patients performed significantly more body weight shifts (p<.01) with more activated back and abdominal muscles (p=.01) and similar temporal variability in muscle activation compared to HCs, while the cLBP patients reported more pain and perceived exertion at the end of prolonged standing. Moreover, both groups had a similar change in strength, postural sway, RE and FRR from before to after prolonged standing, where changes in HC were towards pre-standing values of cLBP patients. Thus, despite a more variable postural strategy, the cLBP patients did not have higher muscle activation variability, but a general increased muscle activation level. This may indicate a reduced ability to individually deactivate trunk muscles. Plausibly, due to the increased variable postural strategy, the cLBP patients could compensate for the relatively high muscle activation level, resulting in normal variation in muscle activation and normal reduction in strength, RE and FRR after prolonged standing. Copyright © 2015 Elsevier B.V. All rights reserved.

Species composition and succession in yellow pine stands following southern pine beetle outbreaks in Tennessee-preliminary results

Treesearch

Christopher M. Oswalt; Sonja N. Oswalt; Jason R. Meade

2016-01-01

The southern pine beetle (Dendroctonus frontalis) is a bark beetle that is native to the Southern United States, including Tennessee. The beetle is periodically epidemic and can cause high levels of mortalityduring epidemic years, particularly in dense or aging pine (Pinus spp.) stands. An epidemic outbreak of the Southern pine...

Landscape genomics reveals altered genome wide diversity within revegetated stands of Eucalyptus microcarpa (Grey Box).

PubMed

Jordan, Rebecca; Dillon, Shannon K; Prober, Suzanne M; Hoffmann, Ary A

2016-12-01

In order to contribute to evolutionary resilience and adaptive potential in highly modified landscapes, revegetated areas should ideally reflect levels of genetic diversity within and across natural stands. Landscape genomic analyses enable such diversity patterns to be characterized at genome and chromosomal levels. Landscape-wide patterns of genomic diversity were assessed in Eucalyptus microcarpa, a dominant tree species widely used in revegetation in Southeastern Australia. Trees from small and large patches within large remnants, small isolated remnants and revegetation sites were assessed across the now highly fragmented distribution of this species using the DArTseq genomic approach. Genomic diversity was similar within all three types of remnant patches analysed, although often significantly but only slightly lower in revegetation sites compared with natural remnants. Differences in diversity between stand types varied across chromosomes. Genomic differentiation was higher between small, isolated remnants, and among revegetated sites compared with natural stands. We conclude that small remnants and revegetated sites of our E. microcarpa samples largely but not completely capture patterns in genomic diversity across the landscape. Genomic approaches provide a powerful tool for assessing restoration efforts across the landscape. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Long river profiles, tectonism, and eustasy: A guide to interpreting fluvial terraces

NASA Technical Reports Server (NTRS)

Merritts, Dorothy J.; Vincent, Kirk R.; Wohl, Ellen E.

1994-01-01

Along three rivers at the Mendocino triple junction, northern California, strath, cut, and fill terraces have formed in response to tectonic and eustatic processes. Detailed surveying and radiometric dating at multiple sites indicate that lower reaches of the rivers are dominated by the effects of oscillating sea level, primarily aggradation and formation of fill terraces during sea level high stands, alternating with deep incision during low stands. A eustasy-driven depositional wedge extends tens of kilometers upstream on all rivers (tapering to zero thickness). This distance is greater than expected from studies of the effects of check dams on much smaller streams elsewhere, due in part to the large size of these rivers. However, the change in gradient is nearly identical to other base level rise studies: the depositional gradient is about half that of the original channel. Middle to upper reaches of each river are dominated by the effects of long-term uplift, primarily lateral and vertical erosion and formation of steep, unpaired strath terraces exposed only upstream of the depositional wedge. Vertical incision at a rate similar to that of uplift has occurred even during the present sea level high stand along rivers with highest uplift rates. Strath terraces have steeper gradients than the modern channel bed and do not merge with marine terraces at the river mouth; consequently, they cannot be used to determine altitudes of sea level high stands. Strath formation is a continuous process of response to long-term uplift, and its occurrence varies spatially along a river depending on stream power, and hence position, upstream. Strath terraces are found only along certain parts of a coastal stream: upstream of the aggradational effects of oscillating sea level, and far enough downstream that stream power is in excess of that needed to transport the prevailing sediment load. For a given size river, the greater the uplift rate, the greater the rate of vertical incision and, consequently, the less the likelihood of strath terrace formation and preservation.

Orientation-dependent energy level alignment and film growth of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on HOPG

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

Lyu, Lu; Niu, Dongmei, E-mail: mayee@csu.edu.cnmailto; Xie, Haipeng

Combining ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, atomic force microscopy, and X-ray diffraction measurements, we performed a systematic investigation on the correlation of energy level alignment, film growth, and molecular orientation of 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) on highly oriented pyrolytic graphite. The molecules lie down in the first layer and then stand up from the second layer. The ionization potential shows a sharp decrease from the lying down region to the standing up region. When C8-BTBT molecules start standing up, unconventional energy level band-bending-like shifts are observed as the film thickness increases. These shifts are ascribed to gradual decreasing of the molecularmore » tilt angle about the substrate normal with the increasing film thickness.« less

Bark beetle-induced tree mortality alters stand energy budgets due to water budget changes

NASA Astrophysics Data System (ADS)

Reed, David E.; Ewers, Brent E.; Pendall, Elise; Frank, John; Kelly, Robert

2018-01-01

Insect outbreaks are major disturbances that affect a land area similar to that of forest fires across North America. The recent mountain pine bark beetle ( D endroctonus ponderosae) outbreak and its associated blue stain fungi ( Grosmannia clavigera) are impacting water partitioning processes of forests in the Rocky Mountain region as the spatially heterogeneous disturbance spreads across the landscape. Water cycling may dramatically change due to increasing spatial heterogeneity from uneven mortality. Water and energy storage within trees and soils may also decrease, due to hydraulic failure and mortality caused by blue stain fungi followed by shifts in the water budget. This forest disturbance was unique in comparison to fire or timber harvesting because water fluxes were altered before significant structural change occurred to the canopy. We investigated the impacts of bark beetles on lodgepole pine ( Pinus contorta) stand and ecosystem level hydrologic processes and the resulting vertical and horizontal spatial variability in energy storage. Bark beetle-impacted stands had on average 57 % higher soil moisture, 1.5 °C higher soil temperature, and 0.8 °C higher tree bole temperature over four growing seasons compared to unimpacted stands. Seasonal latent heat flux was highly correlated with soil moisture. Thus, high mortality levels led to an increase in ecosystem level Bowen ratio as sensible heat fluxes increased yearly and latent heat fluxes varied with soil moisture levels. Decline in canopy biomass (leaf, stem, and branch) was not seen, but ground-to-atmosphere longwave radiation flux increased, as the ground surface was a larger component of the longwave radiation. Variability in soil, latent, and sensible heat flux and radiation measurements increased during the disturbance. Accounting for stand level variability in water and energy fluxes will provide a method to quantify potential drivers of ecosystem processes and services as well as lead to greater confidence in measurements for all dynamic disturbances.

Engineers conduct key water test for A-3 stand

NASA Technical Reports Server (NTRS)

2009-01-01

Water cascades from the A-2 Test Stand at Stennis Space Center as engineers challenge the limits of the high-pressure water system as part of the preparation process for the A-3 Test Stand under construction. Jeff Henderson, test director for Stennis' A Complex, led a series of tests Nov. 16-20, flowing water simultaneously on the A-1 and A-2 stands, followed by the A-1 and B-1 stands, to determine if the high-pressure industrial water facility pumps and the existing pipe system can support the needs of the A-3 stand. The stand is being built to test rocket engines that will carry astronauts beyond low-Earth orbit and will need about 300,000 gallons of water per minute when operating, but the Stennis system never had been tested to that level. The recent tests were successful in showing the water facility pumps can operate at that capacity - reaching 318,000 gallons per minute in one instance. However, officials continue to analyze data to determine if the system can provide the necessary pressure at that capacity and if the delivery system piping is adequate. 'We just think if there's a problem, it's better to identify and address it now rather than when A-3 is finished and it has to be dealt with,' Henderson said.

Bat Response to Differing Fire Severity in Mixed-Conifer Forest California, USA

PubMed Central

Heady, Paul A.; Hayes, John P.; Frick, Winifred F.

2013-01-01

Wildlife response to natural disturbances such as fire is of conservation concern to managers, policy makers, and scientists, yet information is scant beyond a few well-studied groups (e.g., birds, small mammals). We examined the effects of wildfire severity on bats, a taxon of high conservation concern, at both the stand (<1 ha) and landscape scale in response to the 2002 McNally fire in the Sierra Nevada region of California, USA. One year after fire, we conducted surveys of echolocation activity at 14 survey locations, stratified in riparian and upland habitat, in mixed-conifer forest habitats spanning three levels of burn severity: unburned, moderate, and high. Bat activity in burned areas was either equivalent or higher than in unburned stands for all six phonic groups measured, with four groups having significantly greater activity in at least one burn severity level. Evidence of differentiation between fire severities was observed with some Myotis species having higher levels of activity in stands of high-severity burn. Larger-bodied bats, typically adapted to more open habitat, showed no response to fire. We found differential use of riparian and upland habitats among the phonic groups, yet no interaction of habitat type by fire severity was found. Extent of high-severity fire damage in the landscape had no effect on activity of bats in unburned sites suggesting no landscape effect of fire on foraging site selection and emphasizing stand-scale conditions driving bat activity. Results from this fire in mixed-conifer forests of California suggest that bats are resilient to landscape-scale fire and that some species are preferentially selecting burned areas for foraging, perhaps facilitated by reduced clutter and increased post-fire availability of prey and roosts. PMID:23483936

Sea-level history during the Last Interglacial complex on San Nicolas Island, California: implications for glacial isostatic adjustment processes, paleozoogeography and tectonics

USGS Publications Warehouse

Muhs, Daniel R.; Simmons, Kathleen R.; Schumann, R. Randall; Groves, Lindsey T.; Mitrovica, Jerry X.; Laurel, Deanna

2012-01-01

San Nicolas Island, California has one of the best records of fossiliferous Quaternary marine terraces in North America, with at least fourteen terraces rising to an elevation of ~270 m above present-day sea level. In our studies of the lowest terraces, we identified platforms at 38-36 m (terrace 2a), 33-28 m (terrace 2b), and 13-8 m (terrace 1). Uranium-series dating of solitary corals from these terraces yields three clusters of ages: ~120 ka on terrace 2a (marine isotope stage [MIS] 5.5), ~120 and ~100 ka on terrace 2b (MIS 5.5 and 5.3), and ~80 ka (MIS 5.1) on terrace 1. We conclude that corals on terrace 2b that date to ~120 ka were reworked from a formerly broader terrace 2a during the ~100 ka sea stand. Fossil faunas differ on the three terraces. Isolated fragments of terrace 2a have a fauna similar to that of modern waters surrounding San Nicolas Island. A mix of extralimital southern and extralimital northern species is found on terrace 2b, and extralimital northern species are on terrace 1. On terrace 2b, with its mixed faunas, extralimital southern species, indicating warmer than present waters, are interpreted to be from the ~120 ka high sea stand, reworked from terrace 2a. The extralimital northern species on terrace 2b, indicating cooler than present waters, are interpreted to be from the ~100 ka sea stand. The abundant extralimital northern species on terrace 1 indicate cooler than present waters at ~80 ka. Using the highest elevations of the ~120 ka platform of terrace 2a, and assuming a paleo-sea level of +6 m based on previous studies, San Nicolas Island has experienced late Quaternary uplift rates of ~0.25-0.27 m/ka. These uplift rates, along with shoreline angle elevations and ages of terrace 2b (~100 ka) and terrace 1 (~80 ka) yield relative (local) paleo-sea level elevations of +2 to +6 m for the ~100 ka sea stand and -11 to -12 m for the ~80 ka sea stand. These estimates are significantly higher than those reported for the ~100 ka and ~80 ka sea stands on New Guinea and Barbados. Numerical models of the glacial isostatic adjustment (GIA) process presented here demonstrate that these differences in the high stands are expected, given the variable geographic distances between the sites and the former Laurentide and Cordilleran ice sheets. Moreover, the numerical results show that the absolute and differential elevations of the observed high stands provide a potentially important constraint on ice volumes during this time interval and on Earth structure.

Doping of free-standing zinc-blende GaN layers grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Novikov, S. V.; Powell, R. E. L.; Staddon, C. R.; Kent, A. J.; Foxon, C. T.

2014-10-01

Currently there is high level of interest in developing of vertical device structures based on the group III nitrides. We have studied n- and p-doping of free-standing zinc-blende GaN grown by plasma-assisted molecular beam epitaxy (PA-MBE). Si was used as the n-dopant and Mg as the p-dopant for zinc-blende GaN. Controllable levels of doping with Si and Mg in free-standing zinc-blende GaN have been achieved by PA-MBE. The Si and Mg doping depth uniformity through the zinc-blende GaN layers have been confirmed by secondary ion mass spectrometry (SIMS). Controllable Si and Mg doping makes PA-MBE a promising method for the growth of conducting group III-nitrides bulk crystals.

When is pin cherry (Prunus pensylvanica L.) a problem in Allegheny hardwoods?

Treesearch

Todd E. Ristau; Stephen B. Horsley

2006-01-01

Pin cherry (Prunus pensylvanica L.) has important effects on early stand development when it occurs at high densities. We used data describing the first 15 years of stand development in eight clearcuts and used plots that had at least 25 black cherry or 100 desirable seedlings at age 3, as well as different levels of pin cherry stocking. Our findings...

Uranium-Series Ages of Marine Terrace Corals from the Pacific Coast of North America and Implications for Last-Interglacial Sea Level History

USGS Publications Warehouse

Muhs, D.R.; Kennedy, G.L.; Rockwell, T.K.

1994-01-01

Few of the marine terraces along the Pacific coast of North America have been dated using uranium-series techniques. Ten terrace sequences from southern Oregon to southern Baja California Sur have yielded fossil corals in quantities suitable for U-series dating by alpha spectrometry. U-series-dated terraces representing the ???80,000 yr sea-level high stand are identified in five areas (Bandon, Oregon; Point Arena, San Nicolas Island, and Point Loma, California; and Punta Banda, Baja California); terraces representing the ???125,000 yr sea-level high stand are identified in eight areas (Cayucos, San Luis Obispo Bay, San Nicolas Island, San Clemente Island, and Point Loma, California; Punta Bands and Isla Guadalupe, Baja California; and Cabo Pulmo, Baja California Sur). On San Nicolas Island, Point Loma, and Punta Bands, both the ???80,000 and the ???125,000 yr terraces are dated. Terraces that may represent the ???105,000 sea-level high stand are rarely preserved and none has yielded corals for U-series dating. Similarity of coral ages from midlatitude, erosional marine terraces with coral ages from emergent, constructional reefs on tropical coastlines suggests a common forcing mechanism, namely glacioeustatically controlled fluctuations in sea level superimposed on steady tectonic uplift. The low marine terrace dated at ???125,000 yr on Isla Guadalupe, Baja California, presumed to be tectonically stable, supports evidence from other localities for a +6-m sea level at that time. Data from the Pacific Coast and a compilation of data from other coasts indicate that sea levels at ???80,000 and ???105,000 yr may have been closer to present sea level (within a few meters) than previous studies have suggested.

Forest structure and light regimes following moderate wind storms: implications for multi-cohort management.

PubMed

Hanson, Jacob J; Lorimer, Craig G

2007-07-01

Moderate-severity disturbances appear to be common throughout much of North America, but they have received relatively little detailed study compared to catastrophic disturbances and small gap dynamics. In this study, we examined the immediate impact of moderate-intensity wind storms on stand structure, opening sizes, and light regimes in three hemlock-hardwood forests of northeastern Wisconsin. These were compared to three stands managed by single-tree and group selection, the predominant forest management system for northern hardwoods in the region. Wind storms removed an average of 41% of the stand basal area, compared to 27% removed by uneven-aged harvests, but both disturbances removed trees from a wide range of size classes. The removal of nearly half of the large trees by wind in two old-growth stands caused partial retrogression to mature forest structure, which has been hypothesized to be a major disturbance pathway in the region. Wind storms resulted in residual stand conditions that were much more heterogeneous than in managed stands. Gap sizes ranged from less than 10 m2 up to 5000 m2 in wind-disturbed stands, whereas the largest opening observed in managed stands was only 200 m2. Wind-disturbed stands had, on average, double the available solar radiation at the forest floor compared to managed stands. Solar radiation levels were also more heterogeneous in wind-disturbed stands, with six times more variability at small scales (0.1225 ha) and 15 times more variability at the whole-stand level. Modification of uneven-aged management regimes to include occasional harvests of variable intensity and spatial pattern may help avoid the decline in species diversity that tends to occur after many decades of conventional uneven-aged management. At the same time, a multi-cohort system with these properties would retain a high degree of average crown cover, promote structural heterogeneity typical of old-growth forests, and maintain dominance by late-successional species.

Around Marshall

NASA Image and Video Library

2002-10-01

This is a ground level view of Test Stand 500 at the east test area of the Marshall Space Flight Center. Originally constructed in 1966, Test Stand 500 is a multipurpose, dual-position test facility. The stand was utilized to test liquid hydrogen/liquid oxygen turbopumps and combustion devices for the J-2 engine. One test position has a high superstructure with lines and tankage for testing liquid hydrogen and liquid oxygen turbopumps while the other position is adaptable to pressure-fed test programs such as turbo machinery bearings or seals. The facility was modified in 1980 to support Space Shuttle main engine (SSME) bearing testing.

Quantifying climate-growth relationships at the stand level in a mature mixed-species conifer forest.

PubMed

Teets, Aaron; Fraver, Shawn; Weiskittel, Aaron R; Hollinger, David Y

2018-03-11

A range of environmental factors regulate tree growth; however, climate is generally thought to most strongly influence year-to-year variability in growth. Numerous dendrochronological (tree-ring) studies have identified climate factors that influence year-to-year variability in growth for given tree species and location. However, traditional dendrochronology methods have limitations that prevent them from adequately assessing stand-level (as opposed to species-level) growth. We argue that stand-level growth analyses provide a more meaningful assessment of forest response to climate fluctuations, as well as the management options that may be employed to sustain forest productivity. Working in a mature, mixed-species stand at the Howland Research Forest of central Maine, USA, we used two alternatives to traditional dendrochronological analyses by (1) selecting trees for coring using a stratified (by size and species), random sampling method that ensures a representative sample of the stand, and (2) converting ring widths to biomass increments, which once summed, produced a representation of stand-level growth, while maintaining species identities or canopy position if needed. We then tested the relative influence of seasonal climate variables on year-to-year variability in the biomass increment using generalized least squares regression, while accounting for temporal autocorrelation. Our results indicate that stand-level growth responded most strongly to previous summer and current spring climate variables, resulting from a combination of individualistic climate responses occurring at the species- and canopy-position level. Our climate models were better fit to stand-level biomass increment than to species-level or canopy-position summaries. The relative growth responses (i.e., percent change) predicted from the most influential climate variables indicate stand-level growth varies less from to year-to-year than species-level or canopy-position growth responses. By assessing stand-level growth response to climate, we provide an alternative perspective on climate-growth relationships of forests, improving our understanding of forest growth dynamics under a fluctuating climate. © 2018 John Wiley & Sons Ltd.

Caspian sea-level changes during the last millennium: historical and geological evidence from the south Caspian Sea

NASA Astrophysics Data System (ADS)

Naderi Beni, A.; Lahijani, H.; Mousavi Harami, R.; Arpe, K.; Leroy, S. A. G.; Marriner, N.; Berberian, M.; Andrieu-Ponel, V.; Djamali, M.; Mahboubi, A.; Reimer, P. J.

2013-07-01

Historical literature may constitute a valuable source of information to reconstruct sea-level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a comprehensive literature review, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes and to compare the results with other geological and historical findings. The overall results indicate a high-stand during the Little Ice Age, up to -21 m (and extra rises due to manmade river avulsion), with a -28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at -26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin creates local changes in base level. These local base-level changes should be considered in any CSL reconstruction.

Caspian Sea level changes during the last millennium: historical and geological evidences from the south Caspian Sea

NASA Astrophysics Data System (ADS)

Naderi Beni, A.; Lahijani, H.; Mousavi Harami, R.; Arpe, K.; Leroy, S. A. G.; Marriner, N.; Berberian, M.; Andrieu-Ponel, V.; Djamali, M.; Mahboubi, A.

2013-03-01

Historical literature may constitute a valuable source of information to reconstruct sea level changes. Here, historical documents and geological records have been combined to reconstruct Caspian sea-level (CSL) changes during the last millennium. In addition to a literature survey, new data from two short sediment cores were obtained from the south-eastern Caspian coast to identify coastal change driven by water-level changes. Two articulated bivalve shells from the marine facies were radiocarbon dated and calibrated to establish a chronology and to compare them with historical findings. The overall results indicate a high-stand during the Little Ice Age, up to -19 m, with a -28 m low-stand during the Medieval Climate Anomaly, while presently the CSL stands at -26.5 m. A comparison of the CSL curve with other lake systems and proxy records suggests that the main sea-level oscillations are essentially paced by solar irradiance. Although the major controller of the long-term CSL changes is driven by climatological factors, the seismicity of the basin could create locally changes in base level. These local base-level changes should be considered in any CSL reconstruction.

Sea level high stand in Marine Isotope Stage 5e: evidence from coral terraces in Sumba Island, Indonesia

NASA Astrophysics Data System (ADS)

LU, Y.; Rigaud, S.; Leclerc, F.; Liu, X.; Chiang, H. W.; Djamil, Y. S.; Meilano, I.; Bijaksana, S.; Abidin, H. Z.; Tapponnier, P.; Wang, X.

2017-12-01

Uplifted coral reef terraces, possibly spanning the last one million years, are extensively exposed along the northern coast of Sumba Island, Indonesia. We collected a suite of fossil coral samples from the inner edges of terraces at Cape Laundi to study past sea level change, particularly that during the marine isotope stage 5e. These samples were dated by the high-precision U/Th disequilibrium dating methods. For those with δ234U-initial values beyond the range of 145±7‰[1,2] , the open-system model by Thompson et al. [3] was then applied to correct their ages. Only less than 20% of the samples could not derive reasonable ages after the correction, and their abnormally high δ234U-initial values (> 180‰) seem to suggest a limitation of open-system correction with the current model. After the correction of long-term uplift rate of 0.3 mm/kyr, we found that the relative sea level at Cape Laundi, Sumba was 7 m during MIS5e and then dropped to -20 m during the MIS5a and 5c. More importantly, our results indicate that sea level reached a high stand at 129±0.6 ka, supported by both U/Th dates on pristine corals and open-system model corrected ages. In line with the sea level reconstruction from western Australia, our results do not support a second and higher sea level during MIS5e. Moreover, there is no significant lead or lag between the timing of sea level high stand in Sumba and the peak of Northern Hemisphere summer insolation. 1. Robinson et al. (2004) Science. 305: 851-854 2. Cheng et al. (2013) Earth and Planetary Science Letters. 371-372: 82-91 3. Thompson et al. (2003) Earth and Planetary Science Letters. 210: 365-381

[Comparison of three stand-level biomass estimation methods].

PubMed

Dong, Li Hu; Li, Feng Ri

2016-12-01

At present, the forest biomass methods of regional scale attract most of attention of the researchers, and developing the stand-level biomass model is popular. Based on the forestry inventory data of larch plantation (Larix olgensis) in Jilin Province, we used non-linear seemly unrelated regression (NSUR) to estimate the parameters in two additive system of stand-level biomass equations, i.e., stand-level biomass equations including the stand variables and stand biomass equations including the biomass expansion factor (i.e., Model system 1 and Model system 2), listed the constant biomass expansion factor for larch plantation and compared the prediction accuracy of three stand-level biomass estimation methods. The results indicated that for two additive system of biomass equations, the adjusted coefficient of determination (R a 2 ) of the total and stem equations was more than 0.95, the root mean squared error (RMSE), the mean prediction error (MPE) and the mean absolute error (MAE) were smaller. The branch and foliage biomass equations were worse than total and stem biomass equations, and the adjusted coefficient of determination (R a 2 ) was less than 0.95. The prediction accuracy of a constant biomass expansion factor was relatively lower than the prediction accuracy of Model system 1 and Model system 2. Overall, although stand-level biomass equation including the biomass expansion factor belonged to the volume-derived biomass estimation method, and was different from the stand biomass equations including stand variables in essence, but the obtained prediction accuracy of the two methods was similar. The constant biomass expansion factor had the lower prediction accuracy, and was inappropriate. In addition, in order to make the model parameter estimation more effective, the established stand-level biomass equations should consider the additivity in a system of all tree component biomass and total biomass equations.

Tree diversity promotes insect herbivory in subtropical forests of south-east China.

PubMed

Schuldt, Andreas; Baruffol, Martin; Böhnke, Martin; Bruelheide, Helge; Härdtle, Werner; Lang, Anne C; Nadrowski, Karin; von Oheimb, Goddert; Voigt, Winfried; Zhou, Hongzhang; Assmann, Thorsten; Fridley, Jason

2010-07-01

1.Insect herbivory can strongly affect ecosystem processes, and its relationship with plant diversity is a central topic in biodiversity-functioning research. However, very little is known about this relationship from complex ecosystems dominated by long-lived individuals, such as forests, especially over gradients of high plant diversity.2.We analysed insect herbivory on saplings of 10 tree and shrub species across 27 forest stands differing in age and tree species richness in an extraordinarily diverse subtropical forest ecosystem in China. We tested whether plant species richness significantly influences folivory in these highly diverse forests or whether other factors play a more important role at such high levels of phytodiversity.3.Leaf damage was assessed on 58 297 leaves of 1284 saplings at the end of the rainy season in 2008, together with structural and abiotic stand characteristics.4.Species-specific mean damage of leaf area ranged from 3% to 16%. Herbivory increased with plant species richness even after accounting for potentially confounding effects of stand characteristics, of which stand age-related aspects most clearly covaried with herbivory. Intraspecific density dependence or other abiotic factors did not significantly influence overall herbivory across forest stands.5.Synthesis.The positive herbivory-plant diversity relationship indicates that effects related to hypotheses of resource concentration, according to which a reduction in damage by specialized herbivores might be expected as host plant concentration decreases with increasing plant diversity, do not seem to be major determinants for overall herbivory levels in our phytodiverse subtropical forest ecosystem. We discuss the potential role of host specificity of dominant herbivores, which are often expected to show a high degree of specialization in many (sub)tropical forests. In the forest system we studied, a much higher impact of polyphagous species than traditionally assumed might explain the observed patterns, as these species can profit from a broad dietary mix provided by high plant diversity. Further testing is needed to experimentally verify this assumption.

Mapping of past stand-level forest disturbances and estimation of time since disturbance using simulated spaceborne LiDAR data

NASA Astrophysics Data System (ADS)

Sanchez Lopez, N.; Hudak, A. T.; Boschetti, L.

2017-12-01

Explicit information on the location, the size or the time since disturbance (TSD) at the forest stand level complements field inventories, improves the monitoring of forest attributes and the estimation of biomass and carbon stocks. Even-aged stands display homogenous structural parameters that have often been used as a proxy of stand age. Consequently, performing object-oriented analysis on Light Detection and Ranging (LiDAR) data has potential to detect historical stand-replacing disturbances. Recent research has shown good results in the delineation of forest stands as well as in the prediction of disturbance occurrence and TSD using airborne LiDAR data. Nevertheless, the use of airborne LiDAR for systematic monitoring of forest stands is limited by the sporadic availability of data and its high cost compared to satellite instruments. NASA's forthcoming Global Ecosystem Dynamics Investigations (GEDI) mission will provide systematically data on the vertical structure of the vegetation, but its use presents some challenges compared to the common discrete-return airborne LiDAR. GEDI will be a waveform instrument, hence the summary metrics will be different to those obtained with airborne LiDAR, and the sampling configuration could limit the utility of the data, especially on heterogeneous landscapes. The potential use of GEDI data for forest characterization at the stand level would therefore depend on the predictive power of the GEDI footprint metrics, and on the density of point samples relative to forest stand size (i.e. the number of observation/footprints per stand).In this study, we assess the performance of simulated GEDI-derived metrics for stand characterization and estimation of TSD, and the point density needed to adequately identify forest stands, which translates - due to the fixed sampling configuration - into the minimum temporal interval needed to collect a sufficient number of points. The study area was located in the Clear Creek, Selway River, and Elk Creek watersheds ( 54,000 ha) within the Nez Perce-Clearwater National Forest in Idaho, where airborne LiDAR and reference maps on TSD were available. Simulated GEDI footprints and waveforms were obtained from airborne LiDAR point clouds and the results were compared to similar analysis performed with airborne LiDAR.

Influence of climate on the growth of quaking aspen (Populus tremuloides) in Colorado and southern Wyoming

Treesearch

M. M. Dudley; Jose Negron; N. A. Tisserat; W. D. Shepperd; W. R. Jacobi

2015-01-01

We analyzed a series of increment cores collected from 260 adult dominant or co-dominant quaking aspen (Populus tremuloides Michx.) trees from national forests across Colorado and southern Wyoming in 2009 and 2010. Half of the cores were collected from trees in stands with a high amount of crown dieback, and half were from lightly damaged stands. We define the level of...

Stand quality management of a water oak plantation in Louisiana: preliminary results following thinning

Treesearch

James S. Meadows; Daniel A., Jr. Skojac

2010-01-01

Stand quality management is a new guiding principle in which thinning prescriptions are based on tree quality rather than on residual stand density. We recently initiated a series of hardwood thinning studies to determine the effects of four stand quality management thinning prescriptions on both stand-level and individual-tree-level growth, quality, and value: (1) no...

A Holocene history of dune-mediated landscape change along the southeastern shore of Lake Superior

USGS Publications Warehouse

Loope, Walter L.; Fisher, Timothy G.; Jol, Harry M.; Anderton, John B.; Blewett, William L.

2004-01-01

Causal links that connect Holocene high stands of Lake Superior with dune building, stream damming and diversion and reservoir impoundment and infilling are inferred from a multidisciplinary investigation of a small watershed along the SE shore of Lake Superior. Radiocarbon ages of wood fragments from in-place stumps and soil O horizons, recovered from the bottom of 300-ha Grand Sable Lake, suggest that the near-shore inland lake was formed during multiple episodes of late Holocene dune damming of ancestral Sable Creek. Forest drownings at ~3000, 1530, and 300 cal. years BP are highly correlated with local soil burial events that occurred during high stands of Lake Superior. During these and earlier events, Sable Creek was diverted onto eastward-graded late Pleistocene meltwater terraces. Ground penetrating radar (GPR) reveals the early Holocene valley of Sable Creek (now filled) and its constituent sedimentary structures. Near-planar paleosols, identified with GPR, suggest two repeating modes of landscape evolution mediated by levels of Lake Superior. High lake stands drove stream damming, reservoir impoundment, and eolian infilling of impoundments. Falling Lake Superior levels brought decreased sand supply to dune dams and lowered stream base level. These latter factors promoted stream piracy, breaching of dune dams, and aerial exposure and forestation of infilled lakebeds. The bathymetry of Grand Sable Lake suggests that its shoreline configuration and depth varied in response to events of dune damming and subsequent dam breaching. The interrelated late Holocene events apparent in this study area suggest that variations in lake level have imposed complex hydrologic and geomorphic signatures on upper Great Lakes coasts.

Measuring Students' Physical Activity Levels: Validating SOFIT for Use with High-School Students

ERIC Educational Resources Information Center

van der Mars, Hans; Rowe, Paul J.; Schuldheisz, Joel M.; Fox, Susan

2004-01-01

This study was conducted to validate the System for Observing Fitness Instruction Time (SOFIT) for measuring physical activity levels of high-school students. Thirty-five students (21 girls and 14 boys from grades 9-12) completed a standardized protocol including lying, sitting, standing, walking, running, curl-ups, and push-ups. Heart rates and…

Long-term outcome after adjacent two-level anterior cervical discectomy and fusion using stand-alone plasmaphore-covered titanium cages.

PubMed

Marbacher, Serge; Hidalgo-Staub, Teresa; Kienzler, Jenny; Wüergler-Hauri, Carola; Landolt, Hans; Fandino, Javier

2015-05-01

Reports on long-term outcome of stand-alone contiguous two-level anterior cervical discectomy and fusion (ACDF) using stand-alone Plasmaphore-coated titanium cages (PCTCs) are rare, and data on follow-ups > 3 years are missing. To evaluate the long-term outcome of adjacent two-level microsurgical ACDF using stand-alone PCTC. A total of 33 consecutive patients presented with cervical degenerative disc disease (DDD) underwent contiguous two-level ACDF. Clinical long-term evaluation (mean: 61 ± 14 months) included documentation of neurologic deficits (motor deficits, sensory deficits, reflex status, and gait disturbance), neck pain, and radicular pain. Functional outcome was measured using the Odom criteria, patient-perceived outcome, and evaluation of work status. Radiographs were evaluated to assess intervertebral disc height, subsidence, level of fusion, sagittal balance, and implant position. Surgery was performed at levels C5-C6 and C6-C7 in 30 patients and at C4-C5 and C5-C6 in 3 (mean age: 50.1 ± 7.7 years). Symptoms and neurologic deficits improved as follows: neurologic deficits (pre: 100%; post: 36%), radicular pain (pre: 85%; post: 15%), and neck pain (pre: 94%; post: 33%). Excellent and good functional and subjective outcome was noted in 75%. Cage subsidence was found to be more prominent in the lower (52%) than the upper (36%) mobile cervical segment. Two-level fusion was documented in most patients (n = 29 [88%]). Kyphotic deformity occurred in two cases (n = 2 [6%]). Stand-alone contiguous two-level ACDF using PCPT proved to be effective, yielding good long-term clinical and functional outcomes. The relatively high rate of subsidence did not affect the good clinical and functional long-term outcome. Georg Thieme Verlag KG Stuttgart · New York.

Quaternary sea level high-stand deposits of the southeast U.S. Atlantic Coastal Plain: Age, distribution, and implications.

NASA Astrophysics Data System (ADS)

Poirier, R. K.; Cronin, T. M.; Ghaleb, B.; Portell, R.; Hillaire-Marcel, C.; Wehmiller, J. F.; Thompson, W. G.; Oches, E. A.; Willard, D. A.; Katz, M. E.

2015-12-01

Emerged Quaternary paleo-shorelines and marine deposits provide a more direct way to reconstruct and analyze sea-level variability than methods using oxygen isotope analyses of deep ocean benthic foraminifera. New Uranium-series dates on fossil corals (primarily Astrangia spp. and Septastrea spp.) combined with previously published dates have allowed us to constrain the age, elevation, and geographical distribution of marine sediments deposited in the United States Atlantic Coastal Plain (ACP) from Virginia to Florida during periods of past high relative sea level (SL). We present new dates from deposits (VA/NC: Tabb/Norfolk, Nassawadox, & Omar Formations; SC: Wando, Socastee, & Canepatch Formations; FL: Anastasia, Ft. Thompson, & Bermont Formations) representing interglacial high-stands during Marine Isotope Stages (MIS) 5, 7, 9, and 11. In addition, we incorporate stratigraphic, marine micropaleontologic, and palynologic records with our SL chronology to reconstruct a more complete history of middle-to-late Pleistocene interglacial climates of the ACP. Ultimately, these results will test modeled sea-level fingerprint studies based on various melting scenarios of the Greenland and/or Antarctic ice sheets.

Continuous monitoring bed-level dynamics on an intertidal flat: introducing novel stand-alone high-resolution SED-sensors

NASA Astrophysics Data System (ADS)

Hu, Zhan; Lenting, Walther; van der Wal, Daphne; Bouma, Tjeerd

2015-04-01

Tidal flat morphology is continuously shaped by hydrodynamic force, resulting in highly dynamic bed elevations. The knowledge of short-term bed-level changes is important both for understanding sediment transport processes as well as for assessing critical ecological processes such as e.g. vegetation recruitment chances on tidal flats. Due to the labour involved, manual discontinuous measurements lack the ability to continuously monitor bed-elevation changes. Existing methods for automated continuous monitoring of bed-level changes lack vertical accuracy (e.g., Photo-Electronic Erosion Pin sensor and resistive rod) or limited in spatial application by using expensive technology (e.g., acoustic bed level sensors). A method provides sufficient accuracy with a reasonable cost is needed. In light of this, a high-accuracy sensor (2 mm) for continuously measuring short-term Surface-Elevation Dynamics (SED-sensor) was developed. This SED-sensor makes use of photovoltaic cells and operates stand-alone using internal power supply and data logging system. The unit cost and the labour in deployments is therefore reduced, which facilitates monitoring with a number of units. In this study, the performance of a group of SED-sensors is tested against data obtained with precise manual measurements using traditional Sediment Erosion Bars (SEB). An excellent agreement between the two methods was obtained, indicating the accuracy and precision of the SED-sensors. Furthermore, to demonstrate how the SED-sensors can be used for measuring short-term bed-level dynamics, two SED-sensors were deployed for 1 month at two sites with contrasting wave exposure conditions. Daily bed-level changes were obtained including a severe storm erosion event. The difference in observed bed-level dynamics at both sites was statistically explained by their different hydrodynamic conditions. Thus, the stand-alone SED-sensor can be applied to monitor sediment surface dynamics with high vertical and temporal resolutions, which provides opportunities to pinpoint morphological responses to various forces in a number of environments (e.g. tidal flats, beaches, rivers and dunes).

The limited contribution of large trees to annual biomass production in an old-growth tropical forest.

PubMed

Ligot, Gauthier; Gourlet-Fleury, Sylvie; Ouédraogo, Dakis-Yaoba; Morin, Xavier; Bauwens, Sébastien; Baya, Fidele; Brostaux, Yves; Doucet, Jean-Louis; Fayolle, Adeline

2018-04-16

Although the importance of large trees regarding biodiversity and carbon stock in old-growth forests is undeniable, their annual contribution to biomass production and carbon uptake remains poorly studied at the stand level. To clarify the role of large trees in biomass production, we used data of tree growth, mortality, and recruitment monitored during 20 yr in 10 4-ha plots in a species-rich tropical forest (Central African Republic). Using a random block design, three different silvicultural treatments, control, logged, and logged + thinned, were applied in the 10 plots. Annual biomass gains and losses were analyzed in relation to the relative biomass abundance of large trees and by tree size classes using a spatial bootstrap procedure. Although large trees had high individual growth rates and constituted a substantial amount of biomass, stand-level biomass production decreased with the abundance of large trees in all treatments and plots. The contribution of large trees to annual stand-level biomass production appeared limited in comparison to that of small trees. This pattern did not only originate from differences in abundance of small vs. large trees or differences in initial biomass stocks among tree size classes, but also from a reduced relative growth rate of large trees and a relatively constant mortality rate among tree size classes. In a context in which large trees are increasingly gaining attention as being a valuable and a key structural characteristic of natural forests, the present study brought key insights to better gauge the relatively limited role of large trees in annual stand-level biomass production. In terms of carbon uptake, these results suggest, as already demonstrated, a low net carbon uptake of old-growth forests in comparison to that of logged forests. Tropical forests that reach a successional stage with relatively high density of large trees progressively cease to be carbon sinks as large trees contribute sparsely or even negatively to the carbon uptake at the stand level. © 2018 by the Ecological Society of America.

Transpiration in an oil palm landscape: effects of palm age

NASA Astrophysics Data System (ADS)

Röll, A.; Niu, F.; Meijide, A.; Hardanto, A.; Hendrayanto; Knohl, A.; Hölscher, D.

2015-10-01

Oil palm (Elaeis guineensis Jacq.) plantations cover large and continuously increasing areas of humid tropical lowlands. Landscapes dominated by oil palms usually consist of a mosaic of mono-cultural, homogeneous stands of varying age, which may be heterogeneous in their water use characteristics. However, studies on the water use characteristics of oil palms are still at an early stage and there is a lack of knowledge on how oil palm expansion will affect the major components of the hydrological cycle. To provide first insights into hydrological landscape-level consequences of oil palm cultivation, we derived transpiration rates of oil palms in stands of varying age, estimated the contribution of palm transpiration to evapotranspiration, and analyzed the influence of fluctuations in environmental variables on oil palm water use. We studied 15 two- to 25-year old stands in the lowlands of Jambi, Indonesia. A sap flux technique with an oil palm specific calibration and sampling scheme was used to derive leaf-, palm- and stand-level water use rates in all stands under comparable environmental conditions. Additionally, in a two- and a 12-year old stand, eddy covariance measurements were conducted to derive evapotranspiration rates. Water use rates per leaf and palm increased 5-fold from an age of 2 years to a stand age of approx. 10 years and then remained relatively constant. A similar trend was visible, but less pronounced, for estimated stand transpiration rates of oil palms; they varied 12-fold, from 0.2 mm day-1 in a 2-year old to 2.5 mm day-1 in a 12-year old stand, showing particularly high variability in transpiration rates among medium-aged stands. Comparing sap flux and eddy-covariance derived water fluxes suggests that transpiration contributed 8 % to evapotranspiration in the 2-year old stand and 53 % in the 12-year old stand, indicating variable and substantial additional sources of evaporation, e.g., from the soil, the ground vegetation and from trunk epiphytes. Diurnally, oil palm transpiration rates were characterized by an early peak between 10 and 11 a.m.; there was a pronounced hysteresis in the leaf water use response to changes in vapor pressure deficit for all palms of advanced age. On the day-to-day basis this resulted in a relatively low variability of oil palm water use regardless of fluctuations in vapor pressure deficit and radiation. We conclude that oil palm dominated landscapes show some spatial variations in (evapo)transpiration rates, e.g., due to varying age-structures, but that the temporal variability of oil palm transpiration is rather low. The stand transpiration of some of the studied oil palm stands was as high or even higher than values reported for different tropical forests, indicating a high water use of oil palms under yet to be explained site or management conditions. Our study provides first insights into the eco-hydrological characteristics of oil palms as well as a first estimate of oil palm water use across a gradient of plantation age. It sheds first light on some of the hydrological consequences of the continuing expansion of oil palm plantations.

Iterative development of Stand Up Australia: a multi-component intervention to reduce workplace sitting

PubMed Central

2014-01-01

Background Sitting, particularly in prolonged, unbroken bouts, is widespread within the office workplace, yet few interventions have addressed this newly-identified health risk behaviour. This paper describes the iterative development process and resulting intervention procedures for the Stand Up Australia research program focusing on a multi-component workplace intervention to reduce sitting time. Methods The development of Stand Up Australia followed three phases. 1) Conceptualisation: Stand Up Australia was based on social cognitive theory and social ecological model components. These were operationalised via a taxonomy of intervention strategies and designed to target multiple levels of influence including: organisational structures (e.g. via management consultation), the physical work environment (via provision of height-adjustable workstations), and individual employees (e.g. via face-to-face coaching). 2) Formative research: Intervention components were separately tested for their feasibility and acceptability. 3) Pilot studies: Stand Up Comcare tested the integrated intervention elements in a controlled pilot study examining efficacy, feasibility and acceptability. Stand Up UQ examined the additional value of the organisational- and individual-level components over height-adjustable workstations only in a three-arm controlled trial. In both pilot studies, office workers’ sitting time was measured objectively using activPAL3 devices and the intervention was refined based on qualitative feedback from managers and employees. Results Results and feedback from participants and managers involved in the intervention development phases suggest high efficacy, acceptance, and feasibility of all intervention components. The final version of the Stand Up Australia intervention includes strategies at the organisational (senior management consultation, representatives consultation workshop, team champions, staff information and brainstorming session with information booklet, and supportive emails from managers to staff), environmental (height-adjustable workstations), and individual level (face-to-face coaching session and telephone support). Stand Up Australia is currently being evaluated in the context of a cluster-randomised controlled trial at the Department of Human Services (DHS) in Melbourne, Australia. Conclusions Stand Up Australia is an evidence-guided and systematically developed workplace intervention targeting reductions in office workers’ sitting time. PMID:24559162

Canopy transpiration of pure and mixed forest stands with variable abundance of European beech

NASA Astrophysics Data System (ADS)

Gebauer, Tobias; Horna, Viviana; Leuschner, Christoph

2012-06-01

SummaryThe importance of tree species identity and diversity for biogeochemical cycles in forests is not well understood. In the past, forestry has widely converted mixed forests to pure stands while contemporary forest policy often prefers mixed stands again. However, the hydrological consequences of these changes remain unclear. We tested the hypotheses (i) that significant differences in water use per ground area exist among the tree species of temperate mixed forests and that these differences are more relevant for the amount of stand-level canopy transpiration (Ec) than putative complementarity effects of tree water use, and (ii) that the seasonal patterns of Ec in mixed stands are significantly influenced by the identity of the present tree species. We measured xylem sap flux during 2005 (average precipitation) and 2006 (relatively dry) synchronously in three nearby old-growth forest stands on similar soil differing in the abundance of European beech (pure beech stand, 3-species stand with 70% beech, 5-species stand with <10% beech). In summer 2005 with average rainfall, Ec was 50% higher in the beech-poor 5-species stand than in the two stands with moderate to high beech presence (158 vs. 97 and 101 mm yr-1); in the dry summer 2006, all stands converged toward similar Ec totals (128-139 mm yr-1). Species differences in Ec were large on a sapwood area basis, reflecting a considerable variation in hydraulic architecture and leaf conductance regulation among the co-existing species. Moreover, transpiration per crown projection area (ECA) also differed up to 5-fold among the different species in the mixed stands, probably reflecting contrasting sapwood/crown area ratios. We conclude that Ec is not principally higher in mixed forests than in pure beech stands. However, tree species-specific traits have an important influence on the height of Ec and affect its seasonal variation. Species with a relatively high ECA (notably Tilia) may exhaust soil water reserves early in summer, thereby increasing drought stress in dry years and possibly reducing ecosystem stability in mixed forests.

Credit WCT. Photographic copy of photograph, low level aerial view ...

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

Credit WCT. Photographic copy of photograph, low level aerial view of Test Stand "D," looking due south, after completion of Dd station installation in 1961. Note Test Stand "D" "neutralization pond" to immediate southeast of tower. A steel barrier north of and parallel to the Dd station separates fuel run tanks (on south side obscured from view) from oxidizer run tanks (on north side). Small Dj injector test stand is visible to the immediate left of oxidizer run tanks; it is oriented on a northeast/southwest diagonal to the Dd test station. The large tank to the north of the oxidizer run tanks (near center bottom of view) is an oxidizer storage tank for nitrogen tetroxide. Slender tanks to the northwest of the tower (lower right of view) contain high pressure nitrogen gas. A large vertical tank at the base of the tower contains distilled water for flushing propellant lines. (JPL negative no. 384-2997-B, 12 December 1961) - Jet Propulsion Laboratory Edwards Facility, Test Stand D, Edwards Air Force Base, Boron, Kern County, CA

Light-use efficiency of native and hybrid poplar genotypes at high levels of intracanopy competition

Treesearch

D. Scott Green; Eric L. Kruger; Glen R, Stanosz; J. G. Isebrands

2001-01-01

In southern Wisconsin, U.S.A., tree growth and associated canopy traits were compared among five native and hybrid genotypes of poplar (Populus spp.) in replicated, monoclonal stands planted at a 1 x 1 m spacing. The overall objective of this study was to assess clonal suitability to cultural conditions entailing high levels of intracanopy...

Inflight exercise affects stand test responses after space flight

NASA Technical Reports Server (NTRS)

Lee, S. M.; Moore, A. D. Jr; Fritsch-Yelle, J. M.; Greenisen, M. C.; Schneider, S. M.

1999-01-01

PURPOSE: The purpose of this study was to determine whether exercise performed by Space Shuttle crew members during short-duration space flights (9-16 d) affects the heart rate (HR) and blood pressure (BP) responses to standing within 2-4 h of landing. METHODS: Thirty crew members performed self-selected inflight exercise and maintained exercise logs to monitor their exercise intensity and duration. Two subjects participated in this investigation during two different flights. A 10-min stand test, preceded by at least 6 min of quiet supine rest, was completed 10-15 d before launch (PRE) and within 4 h of landing (POST). Based upon their inflight exercise records, subjects were grouped as either high (HIex: > or = 3 times/week, HR > or = 70% HRmax, > or = 20 min/session, N = 11), medium (MEDex: > or = 3 times/week, HR < 70% HRmax, > or = 20 min/session, N = 10), or low (LOex: < or = 3 times/week, HR and duration variable, N = 11) exercisers. HR and BP responses to standing were compared between groups (ANOVA, P < or = 0.05). RESULTS: There were no PRE differences between the groups in supine or standing HR and BP. Although POST supine HR was similar to PRE, all groups had an increased standing HR compared with PRE. The increase in HR upon standing was significantly greater after flight in the LOex group (36 +/- 5 bpm) compared with HIex or MEDex groups (25 +/- 1 bpm; 22 +/- 2 bpm). Similarly, the decrease in pulse pressure (PP) from supine to standing was unchanged after space flight in the MEDex and HIex groups but was significantly greater in the LOex group (PRE: -9 +/- 3; POST: -19 +/- 4 mm Hg). CONCLUSIONS: Thus, moderate to high levels of inflight exercise attenuated HR and PP responses to standing after space flight.

Effect of In-Flight Exercise and Extravehicular Activity on Postflight Stand Tests

NASA Technical Reports Server (NTRS)

Lee, Stuart M. C.; Moore, Alan D., Jr.; Fritsch-Yelle, Janice; Greenisen, Michael; Schneider, Suzanne M.; Foster, Philip P.

2000-01-01

The purpose of this study was to determine whether exercise performed by Space Shuttle crewmembers during short-duration spaceflights (9-16 days) affects the heart rate (HR) and blood pressure (BP) responses to standing within 2-4 hr of landing. Thirty crewmembers performed self-selected in-flight exercise and maintained exercise logs to monitor their exercise intensity and duration. A 10min stand test, preceded by at least 6 min of quiet supine rest, was completed 10- 15 d before launch (PRE) and within four hours of landing (POST). Based upon their in-flight exercise records, subjects were grouped as either high (HIex: = 3x/week, HR = 70% ,HRMax, = 20 min/session, n = 11), medium (MEDex: = 3x/week, HR = 70% HRmax, = 20 min/session, n = 10), or low (LOex: = 3x/week, HR and duration variable, n = 11) exercisers. HR and BP responses to standing were compared between groups (ANOVA, or analysis of variance, P < 0.05). There were no PRE differences between the groups in supine or standing HR and BP. Although POST supine HR was similar to PRE, all groups had an increased standing HR compared to PRE. The increase in HR upon standing was significantly greater after flight in the LOex group (36+/-5 bpm) compared to HIex or MEDex groups (25+/-1bpm; 22+/-2 bpm). Similarly, the decrease in pulse pressure (PP) from supine to standing was unchanged after spaceflight in the MEDex and HIex groups, but was significantly less in the LOex group (PRE: -9+/- 3, POST: -19+/- 4 mmHg). Thus, moderate to high levels of in-flight exercise attenuated HR and PP responses to standing after spaceflight compared.

An Interview with Stephen King.

ERIC Educational Resources Information Center

Janeczko, Paul

1980-01-01

The author of five best-selling novels, including "Carrie,""Salem's Lot,""The Shining,""The Stand," and "The Dead Zone," discusses the teaching of creative writing at high school and college levels. (DF)

Long-Term Trends In Loblolly Pine Productivity And Stand Characteristics In Response To Stand Density And Fertilization In The Western Gulf Region

Treesearch

M.A. Sword; J. L. Chambers; Z. Tang; T. J. Dean; J. C. Goelz

2002-01-01

Two levels each of fertilization and stand density were established to create four environments in a 7-year-old loblolly pine plantation on a N and P deficient western Gulf Coastal Plain site in Louisiana. Levels of fertilization were no fertilization and application of 120 lb N and 134 lb P/ac. Levels of stand density were the original stocking (1,210 trees/ac), and...

Stocking equations for regeneration in mixed oak stands

Treesearch

Songlin Fei; Kim C. Steiner; James C. Finley

2007-01-01

Regeneration stocking equations for mixed-oak stands were developed based on data collected from nearly 14,000 plots in the central Appalachians. Maximum stand density was identified by plotting aggregate height against number of seedlings per plot, and was used as the reference level of the average maximum stand density (100 percent stocking or A-level stocking)....

Early competition shapes maize whole-plant development in mixed stands

PubMed Central

Evers, Jochem B.

2014-01-01

Mixed cropping is practised widely in developing countries and is gaining increasing interest for sustainable agriculture in developed countries. Plants in intercrops grow differently from plants in single crops, due to interspecific plant interactions, but adaptive plant morphological responses to competition in mixed stands have not been studied in detail. Here the maize (Zea mays) response to mixed cultivation with wheat (Triticum aestivum) is described. Evidence is provided that early responses of maize to the modified light environment in mixed stands propagate throughout maize development, resulting in different phenotypes compared with pure stands. Photosynthetically active radiation (PAR), red:far-red ratio (R:FR), leaf development, and final organ sizes of maize grown in three cultivation systems were compared: pure maize, an intercrop with a small distance (25cm) between maize and wheat plants, and an intercop with a large distance (44cm) between the maize and the wheat. Compared with maize in pure stands, maize in the mixed stands had lower leaf and collar appearance rates, increased blade and sheath lengths at low ranks and smaller sizes at high ranks, increased blade elongation duration, and decreased R:FR and PAR at the plant base during early development. Effects were strongest in the treatment with a short distance between wheat and maize strips. The data suggest a feedback between leaf initiation and leaf emergence at the plant level and coordination between blade and sheath growth at the phytomer level. A conceptual model, based on coordination rules, is proposed to explain the development of the maize plant in pure and mixed stands. PMID:24307719

Development of prolonged standing strain index to quantify risk levels of standing jobs.

PubMed

Halim, Isa; Omar, Abdul Rahman

2012-01-01

Many occupations in industry such as metal stamping workers, electronics parts assembly operators, automotive industry welders, and lathe operators require working in a standing posture for a long time. Prolonged standing can contribute to discomfort and muscle fatigue particularly in the back and legs. This study developed the prolonged standing strain index (PSSI) to quantify the risk levels caused by standing jobs, and proposed recommendations to minimize the risk levels. Risk factors associated with standing jobs, such as working posture, muscles activity, standing duration, holding time, whole-body vibration, and indoor air quality, were the basis for developing the PSSI. All risk factors were assigned multipliers, and the PSSI was the product of those multipliers. Recommendations for improvement are based on the PSSI; however, extensive studies are required to validate their effectiveness. multipliers, and the PSSI was the product of those multipliers. Recommendations for improvement are based on the PSSI; however, extensive studies are required to validate their effectiveness.

Breeding season demography and movements of Eastern Towhees at the Savannah River Site, South Carolina

USGS Publications Warehouse

Krementz, D.G.; Powell, L.A.

2000-01-01

The Eastern Towhee (Pipilo erythrophthalmus) has undergone population declines across much of its range, especially in New England. Despite being a widespread and, at one time, a common species, relatively little is known about its natural history, ecology, or demographics. We conducted baseline research on Eastern Towhees at the Savannah River Site, South Carolina, in 1995 and 1996 to estimate breeding season survival rates, nest success rates, breeding densities, and daily movements. We also were interested in whether towhees had differences in survival and movement rates between young and mature managed pine stands. We found that survival rates during the breeding season of radio-marked towhees did not vary by sex or stand type. Daily nest success rates were very low [0.629 + 0.088 (SE)] as a result of high predation levels. Abundance estimates adjusted for sampling effort differed between years. In 1995, the abundance estimate was significantly lower in mature stands (7.1 + 0.47) than in-young stands (9.6 + 0.60) while in 1996, there was no different between mature stands (26.2 ? 5.67) and young stands (16.5 ? 3.39). Average daily movements by radio-marked towhees did not vary by sex or stand type. Movements among adjacent stands were common, and sometimes great distances.

Correlation between High Density Lipoprotein Cholesterol (HDL) Level and Aerobic Activity Level.

DTIC Science & Technology

1987-04-01

over a 40 day period for HDtJICholesteroll and Total Choleis- added with the "reverse" technique, This technique is only poai- tarot . The results are...Stand- tarot and Total Cholestero levels, it is beat that eet laoatr ard and a control Serum were each analyzed 10 times giving the * determinle its

Loss of genetic diversity as a consequence of selection in response to high pCO2.

PubMed

Lloyd, Melanie M; Makukhov, April D; Pespeni, Melissa H

2016-10-01

Standing genetic variation may allow for rapid evolutionary response to the geologically unprecedented changes in global conditions. However, there is little known about the consequences of such rapid evolutionary change. Here, we measure genetic responses to experimental low and high p CO 2 levels in purple sea urchin larvae, Strongylocentrotus purpuratus . We found greater loss of nucleotide diversity in high p CO 2 levels (18.61%; 900 μatm) compared to low p CO 2 levels (10.12%; 400 μatm). In the wild, this loss could limit the evolutionary capacity of future generations. In contrast, we found minimal evidence that purple sea urchin larvae physiologically respond to high p CO 2 through alternative splicing of transcripts (11 genes), despite a strong signal of alternative splicing between different developmental stages (1193 genes). However, in response to high p CO 2 , four of the 11 alternatively spliced transcripts encoded ribosomal proteins, suggesting the regulation of translation as a potential response mechanism. The results of this study indicate that while the purple urchin presently may have enough standing genetic variation in response to rapid environmental change, this reservoir of resilience is a finite resource and could quickly diminish.

Mathematics for the Student Scientist.

ERIC Educational Resources Information Center

Lauten, A. Darien; Lauten, Gary N.

1998-01-01

Describes the Earth Day-Forest Watch Program which introduces kindergarten through high school level students to field laboratory and satellite-data analysis methods for assessing the health of Eastern White Pine forest stands. (DDR)

Highly conductive and porous activated reduced graphene oxide films for high-power supercapacitors.

PubMed

Zhang, Li Li; Zhao, Xin; Stoller, Meryl D; Zhu, Yanwu; Ji, Hengxing; Murali, Shanthi; Wu, Yaping; Perales, Stephen; Clevenger, Brandon; Ruoff, Rodney S

2012-04-11

We present a novel method to prepare highly conductive, free-standing, and flexible porous carbon thin films by chemical activation of reduced graphene oxide paper. These flexible carbon thin films possess a very high specific surface area of 2400 m(2) g(-1) with a high in-plane electrical conductivity of 5880 S m(-1). This is the highest specific surface area for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films as electrodes demonstrated an excellent high-frequency response, an extremely low equivalent series resistance on the order of 0.1 ohm, and a high-power delivery of about 500 kW kg(-1). While higher frequency and power values for graphene materials have been reported, these are the highest values achieved while simultaneously maintaining excellent specific capacitances and energy densities of 120 F g(-1) and 26 W h kg(-1), respectively. In addition, these free-standing thin films provide a route to simplify the electrode-manufacturing process by eliminating conducting additives and binders. The synthetic process is also compatible with existing industrial level KOH activation processes and roll-to-roll thin-film fabrication technologies. © 2012 American Chemical Society

Birth Defects Diagnosis

MedlinePlus

... screen tests the levels of 4 proteins AFP (alpha-fetoprotein), hCG, estriol, and inhibin-A. Generally, the maternal ... which an amniocentesis tests. AFP AFP stands for alpha-fetoprotein, a protein the unborn baby produces. A high ...

Effect of Caregiver Driven Robot-Assisted In-Ward Training in Subacute Stroke Patients: A Case Series

PubMed Central

2018-01-01

Objective To evaluate the effect of caregiver driven robot-assisted in-ward training in subacute stroke patients. Methods A retrospective evaluation was performed for patients treated with caregiver driven robot-assisted in-ward training to retain gait function from June 2014 and December 2016. All patients received more than 2 weeks of caregiver driven robot-assisted in-ward training after undergoing conventional programs. The robot was used as a sitting device, a standing frame, or a high-walker depending on functional status of the patient. Patients were evaluated before and after robot training. Patient records were assessed by Korean version of Modified Barthel Index (K-MBI), Functional Independence Measure (FIM), and Functional Ambulation Category (FAC). Results Initially, patients used the robot as a sitting device (n=6), a standing frame (n=7), or a partial body-weight support high-walker (n=2). As patient functions were improved, usage level of the robot was changed to the next level. At the end of the treatment, the robot was used as a sitting device (n=1), a standing frame (n=6), or high-walker (n=8). Scores of K-MBI (Δ17.47±10.72) and FIM (Δ19.80±12.34) were improved in all patients. Conclusion Patients' usage level of the robot and functional scores were improved. Therefore, performing additional caregiver driven robot-assisted in-ward training is feasible and beneficial for subacute stroke patients. PMID:29765872

Effect of Caregiver Driven Robot-Assisted In-Ward Training in Subacute Stroke Patients: A Case Series.

PubMed

Kim, Sang Beom; Lee, Kyeong Woo; Lee, Jong Hwa; Lee, Sook Joung; Park, Jin Gee; Park, Joo Won

2018-04-01

To evaluate the effect of caregiver driven robot-assisted in-ward training in subacute stroke patients. A retrospective evaluation was performed for patients treated with caregiver driven robot-assisted in-ward training to retain gait function from June 2014 and December 2016. All patients received more than 2 weeks of caregiver driven robot-assisted in-ward training after undergoing conventional programs. The robot was used as a sitting device, a standing frame, or a high-walker depending on functional status of the patient. Patients were evaluated before and after robot training. Patient records were assessed by Korean version of Modified Barthel Index (K-MBI), Functional Independence Measure (FIM), and Functional Ambulation Category (FAC). Initially, patients used the robot as a sitting device (n=6), a standing frame (n=7), or a partial body-weight support high-walker (n=2). As patient functions were improved, usage level of the robot was changed to the next level. At the end of the treatment, the robot was used as a sitting device (n=1), a standing frame (n=6), or high-walker (n=8). Scores of K-MBI (Δ17.47±10.72) and FIM (Δ19.80±12.34) were improved in all patients. Patients' usage level of the robot and functional scores were improved. Therefore, performing additional caregiver driven robot-assisted in-ward training is feasible and beneficial for subacute stroke patients.

Chapter 5 - Tree Mortality

Treesearch

Mark J. Ambrose

2018-01-01

Tree mortality is a natural process in all forest ecosystems. High mortality can be an indicator of forest health problems. On aregional scale, high mortality levels may indicate widespread insect or disease impacts. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands. The approach...

Tree Mortality

Treesearch

Mark J. Ambrose

2012-01-01

Tree mortality is a natural process in all forest ecosystems. However, extremely high mortality also can be an indicator of forest health issues. On a regional scale, high mortality levels may indicate widespread insect or disease problems. High mortality may also occur if a large proportion of the forest in a particular region is made up of older, senescent stands....

Seismic tremor and gravity measurements at Inferno Crater Lake, Waimangu Geothermal Field, New Zealand

NASA Astrophysics Data System (ADS)

O'Brien, J. F.; Jolly, A. D.; Fournier, N.; Cole-Baker, J.; Hurst, T.; Roman, D. C.

2011-12-01

Volcanic crater lakes are often associated with active hydrothermal systems that induce cyclic behavior in the lake's level, temperature, and chemistry. Inferno Crater Lake, located in the Waimangu geothermal field within the Taupo Volcanic Zone (TVZ) on the North Island of New Zealand exhibits lake level fluctuations of >7m, and temperature fluctuations >40°C with a highly variable periodicity. Seismic and gravity monitoring of Inferno Lake was carried out from December, 2009 - March, 2010 and captured a full cycle of lake fluctuation. Results indicate that this cycle consisted of ~5 smaller fluctuations of ~3m in lake level followed by a larger fluctuation of ~7m. A broadband seismometer recorded strong seismic tremor in the hours leading up to each of the minor and major high stands in lake level. Spectral analysis of the tremor shows dominant frequencies in the range of ~10Hz and a fundamental harmonic frequency located in the 1Hz range. The 1Hz frequency band exhibits gliding spectral lines which increase in frequency at the end of each tremor period. Particle motion analysis of harmonic tremor waveforms indicate a ~100m upward migration of the source location from the onset of tremor until it ceases at the peak of each lake level high stand. Particle motions also indicate an azimuthal migration of the source by ~30° from the overflow outlet region of the lake toward the central vent location during the course of the tremor and lake level increase. Lake water temperature has a direct relationship with lake level and ranges between ~40°C - ~80°C. Gravity fluctuations were also continuously monitored using a Micro-g-LaCoste gPhone relative gravity meter with a 1Hz sampling rate and precision of 1 microgal. These data indicate a direct relationship between lake level and gravity showing a net increase of ~100 microgals between lake level low and high stands. A piezometer located beside the lake indicates an inflow of ground water into the subsoil during periods of lake level increase and outflow of groundwater during lake level decrease resulting in a ~0.5m overall change between high and low stands and suggests that groundwater flow underneath the gravity meter may be playing a significant role in observed gravity changes. Overall, the results are consistent with a hydrothermal system at Inferno Lake consisting of a one-phase liquid layer overlying a 2-phase liquid/gas layer. Heating from below initiates boiling at the boundary between the one- and two-phase regions, and may act as the source of harmonic tremor within the conduit system. The dynamic expansion and collapse of the two-phase layer may modify the resonator geometry and internal properties, producing the harmonic excitation and apparent source position migration. Further study of Inferno Lake's hydrothermal system will aid in understanding its complex nature and that of other volcanic lake-hydrothermal systems.

Heart rate variability in elite sprinters: effects of gender and body position.

PubMed

Abad, Cesar; Kobal, Ronaldo; Kitamura, Katia; Gil, Saulo; Pereira, Lucas; Loturco, Irineu; Nakamura, Fábio

2017-07-01

To describe the heart rate variability (HRV) of high-level sprinters in both the supine and standing positions, the HRV of 7 male (24 ± 6 years; 80 ± 8 kg and 182 ± 7 cm) and 11 female (27 ± 5 years; 61 ± 4 kg; 167 ± 5 cm) high-level Brazilian sprinters was measured in the standing and supine body positions in both the time and frequency domains. The heart rate (HR) and the time (SDNN, RMSSD) and frequency (LF; HF and LF:HF) domains of the HRV were assessed. Natural log-transformations (ln) of all HRV indices were log-transformed prior to analysis to reduce bias arising from non-uniformity of error. The Cohen's effect size and magnitude-based inference (MBI) were obtained for comparisons. The results suggest higher cardiac autonomic stress in the standing position than in the supine for both genders. With the exception of the lnSDNN that showed possibly MBI in female athletes, all other HRV indices presented a likely or almost certainly MBI. Male athletes demonstrated a higher lnSDNN in the supine body position (very likely MBI) and a higher HR in the standing position (very likely MBI) than females. In conclusion, elite sprinters (independent of the gender) present lower HRV in the standing position than in the supine position, but males present a more notable change in cardiac autonomic stress than female athletes. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Standing Height as a Prevention Measure for Overuse Injuries of the Back in Alpine Ski Racing: A Kinematic and Kinetic Study of Giant Slalom

PubMed Central

Spörri, Jörg; Kröll, Josef; Fasel, Benedikt; Aminian, Kamiar; Müller, Erich

2018-01-01

Background: In alpine ski racing, typical loading patterns of the back include a combined occurrence of spinal bending, torsion, and high peak loads. These factors are known to be associated with high spinal disc loading and have been suggested to be attributable to different types of spine deterioration. However, little is known about the effect of standing height (ie, the distance between the bottom of the running surface of the ski and the ski boot sole) on the aforementioned back loading patterns. Purpose: To investigate the effect of reduced standing height on the skier’s overall trunk kinematics and the acting ground-reaction forces in giant slalom (GS) from an overuse injury prevention perspective. Study Design: Controlled laboratory study. Methods: Seven European Cup–level athletes skied a total of 224 GS turns with 2 different pairs of skis varying in standing height. Their overall trunk movement (frontal bending, lateral bending, and torsion angles) was measured based on 2 inertial measurement units located at the sacrum and sternum. Pressure insoles were used to determine the total ground-reaction force. Results: During the turn phase in which the greatest spinal disc loading is expected to occur, significantly lower total ground-reaction forces were observed for skis with a decreased standing height. Simultaneously, the skier’s overall trunk movement (ie, frontal bending, lateral bending, and torsion angles) remained unwaveringly high. Conclusion: Standing height is a reasonable measure to reduce the skier’s overall back loading in GS. Yet, when compared with the effects achievable by increased gate offsets in slalom, for instance, the preventative benefits of decreased standing height seem to be rather small. Clinical Relevance: To reduce the magnitude of overall back loading in GS and to prevent overuse injuries of the back, decreasing standing height might be an efficient approach. Nevertheless, the clinical relevance of the current findings, as well as the effectiveness of the measure “reduced standing height,” must be verified by epidemiological studies before its preventative potential can be judged as conclusive. PMID:29344540

Testing the generality of above-ground biomass allometry across plant functional types at the continent scale.

PubMed

Paul, Keryn I; Roxburgh, Stephen H; Chave, Jerome; England, Jacqueline R; Zerihun, Ayalsew; Specht, Alison; Lewis, Tom; Bennett, Lauren T; Baker, Thomas G; Adams, Mark A; Huxtable, Dan; Montagu, Kelvin D; Falster, Daniel S; Feller, Mike; Sochacki, Stan; Ritson, Peter; Bastin, Gary; Bartle, John; Wildy, Dan; Hobbs, Trevor; Larmour, John; Waterworth, Rob; Stewart, Hugh T L; Jonson, Justin; Forrester, David I; Applegate, Grahame; Mendham, Daniel; Bradford, Matt; O'Grady, Anthony; Green, Daryl; Sudmeyer, Rob; Rance, Stan J; Turner, John; Barton, Craig; Wenk, Elizabeth H; Grove, Tim; Attiwill, Peter M; Pinkard, Elizabeth; Butler, Don; Brooksbank, Kim; Spencer, Beren; Snowdon, Peter; O'Brien, Nick; Battaglia, Michael; Cameron, David M; Hamilton, Steve; McAuthur, Geoff; Sinclair, Jenny

2016-06-01

Accurate ground-based estimation of the carbon stored in terrestrial ecosystems is critical to quantifying the global carbon budget. Allometric models provide cost-effective methods for biomass prediction. But do such models vary with ecoregion or plant functional type? We compiled 15 054 measurements of individual tree or shrub biomass from across Australia to examine the generality of allometric models for above-ground biomass prediction. This provided a robust case study because Australia includes ecoregions ranging from arid shrublands to tropical rainforests, and has a rich history of biomass research, particularly in planted forests. Regardless of ecoregion, for five broad categories of plant functional type (shrubs; multistemmed trees; trees of the genus Eucalyptus and closely related genera; other trees of high wood density; and other trees of low wood density), relationships between biomass and stem diameter were generic. Simple power-law models explained 84-95% of the variation in biomass, with little improvement in model performance when other plant variables (height, bole wood density), or site characteristics (climate, age, management) were included. Predictions of stand-based biomass from allometric models of varying levels of generalization (species-specific, plant functional type) were validated using whole-plot harvest data from 17 contrasting stands (range: 9-356 Mg ha(-1) ). Losses in efficiency of prediction were <1% if generalized models were used in place of species-specific models. Furthermore, application of generalized multispecies models did not introduce significant bias in biomass prediction in 92% of the 53 species tested. Further, overall efficiency of stand-level biomass prediction was 99%, with a mean absolute prediction error of only 13%. Hence, for cost-effective prediction of biomass across a wide range of stands, we recommend use of generic allometric models based on plant functional types. Development of new species-specific models is only warranted when gains in accuracy of stand-based predictions are relatively high (e.g. high-value monocultures). © 2015 John Wiley & Sons Ltd.

Longitudinal performance of a surgically implanted neuroprosthesis for lower-extremity exercise, standing, and transfers after spinal cord injury.

PubMed

Triolo, Ronald J; Bailey, Stephanie Nogan; Miller, Michael E; Rohde, Loretta M; Anderson, James S; Davis, John A; Abbas, James J; DiPonio, Lisa A; Forrest, George P; Gater, David R; Yang, Lynda J

2012-05-01

To investigate the longitudinal performance of a surgically implanted neuroprosthesis for lower-extremity exercise, standing, and transfers after spinal cord injury. Case series. Research or outpatient physical therapy departments of 4 academic hospitals. Subjects (N=15) with thoracic or low cervical level spinal cord injuries who had received the 8-channel neuroprosthesis for exercise and standing. After completing rehabilitation with the device, the subjects were discharged to unrestricted home use of the system. A series of assessments were performed before discharge and at a follow-up appointment approximately 1 year later. Neuroprosthesis usage, maximum standing time, body weight support, knee strength, knee fatigue index, electrode stability, and component survivability. Levels of maximum standing time, body weight support, knee strength, and knee fatigue index were not statistically different from discharge to follow-up (P>.05). Additionally, neuroprosthesis usage was consistent with subjects choosing to use the system on approximately half of the days during each monitoring period. Although the number of hours using the neuroprosthesis remained constant, subjects shifted their usage to more functional standing versus more maintenance exercise, suggesting that the subjects incorporated the neuroprosthesis into their lives. Safety and reliability of the system were demonstrated by electrode stability and a high component survivability rate (>90%). This group of 15 subjects is the largest cohort of implanted lower-extremity neuroprosthetic exercise and standing system users. The safety and efficiency data from this group, and acceptance of the neuroprosthesis as demonstrated by continued usage, indicate that future efforts toward commercialization of a similar device may be warranted. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Standing on a declining surface reduces transient prolonged standing induced low back pain development.

PubMed

Gallagher, Kaitlin M; Callaghan, Jack P

2016-09-01

While alternating standing position on a sloped surface has proven successful at reducing low back pain during standing, the purpose of this study was to evaluate standing solely on a declining surface to isolate the influence of the postural change. Seventeen participants performed two 75-min prolonged standing occupational simulations- level ground and declining surface. Fifty-three percent of participants (9/17) were categorized as pain developers during the level ground standing condition. For these same pain developers, their average maximum pain scores were 58% lower during sloped standing. All participants showed greater hip flexion, trunk-to-thigh angle flexion, and posterior translation of the trunk center of gravity when standing on the sloped surface. These postural changes could cause the muscles crossing the hip posteriorly to increase passive stiffness and assist with stabilizing the pelvis. This study stresses the importance of hip kinematics, not just lumbar spine posture, in reducing prolonged standing induced low back pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Careful logging, partial cutting and the protection of terrestrial and aquatic habitats

Treesearch

Daniel C. Dey

1994-01-01

Stand management activites influence (1) tree growth and quality; (2) stand structure, stocking and composition; (3) wildlife and aquatic habitat quality; and (4) long-term site productivity. The cumulative impacts of stand-level treatments affect ecosystem structure and function at the landscape level.

The distribution of lumbar intervertebral angles in upright standing and extension is related to low back pain developed during standing.

PubMed

Viggiani, Daniel; Gallagher, Kaitlin M; Sehl, Michael; Callaghan, Jack P

2017-11-01

Lumbar lordosis measures are poorly related to clinical low back pain, however using a controlled exposure such as prolonged standing to identify pain groups may clarify this relationship. The purpose of this study was to determine the distribution of lumbar intervertebral angles in asymptomatic persons who do (pain developers) and do not (non-pain developers) develop low back pain during standing. Sagittal plane lumbar spine radiographs of eight pain developers and eight non-pain developers were taken in three poses: upright standing, full extension and full flexion. Measures of vertebral end plate orientations from L1 to S1 were taken in each pose to compute: intervertebral angles, contribution of each level to the total curve, total lordosis, ranges of motion, relative pose positioning within the range of motion, vertebral shape, and lumbar spine recurve. Measures were compared between pain groups and lumbar levels. Pain group differences in intervertebral angles and level contributions were greatest in the full extension pose, with pain developers having greater contributions from higher lumbar levels and fewer contributions from lower levels than non-pain developers. Pain group differences in intervertebral angle distributions were less pronounced in upright standing and non-existent in full flexion. No other measures differentiated pain groups. Although participants had similar gross-lumbar spine curvature characteristics, non-pain developers have more curvature at lower levels in upright standing and full extension. These differences in regional vertebral kinematics may partially be responsible for standing-induced low back pain. Copyright © 2017 Elsevier Ltd. All rights reserved.

Relevance of genetics for conservation policies: the case of Minorcan cork oaks

PubMed Central

Lorenzo, Zaida; Burgarella, Concetta; de Heredia, Unai López; Lumaret, Roselyne; Petit, Rémy J.; Soto, Álvaro; Gil, Luis

2009-01-01

Background and Aims Marginal populations of widely distributed species can be of high conservation interest when they hold a significant or unique portion of the genetic diversity of the species. However, such genetic information is frequently lacking. Here the relevance of genetic surveys to develop efficient conservation strategies for such populations is illustrated using cork oak (Quercus suber) from Minorca (Balearic Islands, Spain) as a case study. Cork oak is highly endangered on the island, where no more than 67 individuals live in small, isolated stands in siliceous sites. As a consequence, it was recently granted protected status. Methods Two Bayesian clustering approaches were used to analyse the genetic structure of the Minorcan population, on the basis of nuclear microsatellite data. The different groups within the island were also compared with additional island and continental populations surrounding Minorca. Key Results Very high genetic diversity was found, with values comparable with those observed in continental parts of the species' range. Furthermore, the Minorcan oak stands were highly differentiated from one another and were genetically related to different continental populations of France and Spain. Conclusions The high levels of genetic diversity and inter-stands differentiation make Minorcan cork oak eligible for specific conservation efforts. The relationship of Minorcan stands to different continental populations in France and Spain probably reflects multiple colonization events. However, discrepancy between chloroplast DNA- and nuclear DNA-based groups does not support a simple scenario of recent introduction. Gene exchanges between neighbouring cork oak stands and with holm oak have created specific and exceptional genetic combinations. They also constitute a wide range of potential genetic resources for research on adaptation to new environmental conditions. Conservation guidelines that take into account these findings are provided. PMID:19671575

Collective hormonal profiles predict group performance.

PubMed

Akinola, Modupe; Page-Gould, Elizabeth; Mehta, Pranjal H; Lu, Jackson G

2016-08-30

Prior research has shown that an individual's hormonal profile can influence the individual's social standing within a group. We introduce a different construct-a collective hormonal profile-which describes a group's hormonal make-up. We test whether a group's collective hormonal profile is related to its performance. Analysis of 370 individuals randomly assigned to work in 74 groups of three to six individuals revealed that group-level concentrations of testosterone and cortisol interact to predict a group's standing across groups. Groups with a collective hormonal profile characterized by high testosterone and low cortisol exhibited the highest performance. These collective hormonal level results remained reliable when controlling for personality traits and group-level variability in hormones. These findings support the hypothesis that groups with a biological propensity toward status pursuit (high testosterone) coupled with reduced stress-axis activity (low cortisol) engage in profit-maximizing decision-making. The current work extends the dual-hormone hypothesis to the collective level and provides a neurobiological perspective on the factors that determine who rises to the top across, not just within, social hierarchies.

Collective hormonal profiles predict group performance

PubMed Central

Akinola, Modupe; Page-Gould, Elizabeth; Mehta, Pranjal H.; Lu, Jackson G.

2016-01-01

Prior research has shown that an individual’s hormonal profile can influence the individual’s social standing within a group. We introduce a different construct—a collective hormonal profile—which describes a group’s hormonal make-up. We test whether a group’s collective hormonal profile is related to its performance. Analysis of 370 individuals randomly assigned to work in 74 groups of three to six individuals revealed that group-level concentrations of testosterone and cortisol interact to predict a group’s standing across groups. Groups with a collective hormonal profile characterized by high testosterone and low cortisol exhibited the highest performance. These collective hormonal level results remained reliable when controlling for personality traits and group-level variability in hormones. These findings support the hypothesis that groups with a biological propensity toward status pursuit (high testosterone) coupled with reduced stress-axis activity (low cortisol) engage in profit-maximizing decision-making. The current work extends the dual-hormone hypothesis to the collective level and provides a neurobiological perspective on the factors that determine who rises to the top across, not just within, social hierarchies. PMID:27528679

[Anthropometrical profile of Brazilian junior volleyball players for different sports requirement levels].

PubMed

Fonseca-Toledo, Cláudio; Roquetti, Paula; Fernandes-Filho, José

2010-12-01

This study was aimed at investigating the anthropometrics characteristics of male Brazilian junior volleyball players, organised into 3 sports requirement groups: high qualification (HQ) formed by the national team, middle qualification (MQ) formed by athletes playing in the Brazilian national championships and low qualification (LQ) formed by players at school level. 101 athletes were observed, HQ (n=16), MQ (n=68) and LQ (n=17), aged 16.7 ± 0.5; 16.6 ± 0.5 and 16.2 ± 0.7 years, respectively. There following were evaluated: body mass, height, standing reach height, % body fat and Heath & Carter somatotype. The statistical analysis was descriptive and inferential, the Kruskal Wallis test being used for detecting differences between groups (p<0.05 significance) and Spearman correlation coefficient for establishing association between anthropometric characteristics and requirement levels, considering p<0,05 e p<0.01 to be significant and highly significant, respectively. Significant differences (p<0.05) were detected between athlete groups for body mass, height, standing reach height and ectomorphy. A "strong" correlation for height and "regular" correlation for standing reach height, body mass and ectomorphy were observed, according to players' height or classification. The results gave normative data for athletes which will allow coaches and physical instructors to use such information during training as a sports' selection instrument for young talented volleyball players.

6. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. ...

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

6. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. Looking south from north wall of terminal room. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Outbreak of Drepanopeziza fungus in aspen forests and variation in stand susceptibility: leaf functional traits, compensatory growth and phenology.

PubMed

Call, Anson C; St Clair, Samuel B

2017-09-01

In the spring of 2015, a severe outbreak of the necrotrophic pathogen Drepanopeziza (also known as Marssonina) spread across large portions of aspen (Populus tremuloides Michx.) forests in the western United States. Among adjacent stands, some were diseased and others were not. Drepanopeziza infection in diseased aspen stands stimulated compensatory growth of second-flush leaves at the top of the canopy. These patterns of infection provided an opportunity to characterize associations of pathogen infection and leaf functional traits. Eight pairs of adjacent healthy and diseased aspen stands were identified across a forest landscape in northern Utah. Average leaf surface area, specific leaf area (SLA), photosynthesis, starch concentration and defense chemistry expression (phenolic glycosides and condensed tannins) were measured on original, first-flush leaves in the lower portion of the tree canopy of healthy and diseased stands and compensatory, second-flush leaves produced in the canopy top of diseased stands. Only first-flush leaves of diseased stands showed high levels of Drepanopeziza infection. Leaf area of second-flush leaves of diseased stands was threefold larger than all other leaf types in healthy or diseased stands. Lower canopy leaves of healthy stands had the highest SLA. Photosynthesis was lowest in infected first-flush leaves, highest in second-flush leaves of diseased stands and intermediate in leaves of healthy stands. Foliar starch concentrations were lower in leaves of diseased stands than leaves from healthy stands. Condensed tannins were greater in second-flush leaves than first-flush leaves in both healthy and diseased stands. Phenolic glycoside concentrations were lowest in infected leaves of diseased stands. Diseased stands leafed out a week earlier in the spring than healthy stands, which may have exposed their emerging leaves to rainy conditions that promote Drepanopeziza infection. Compensatory leaf regrowth of diseased stands appears to offset some of the functional loss (i.e., photosynthetic capacity) of infected leaves. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Partners in Physics with Colorado School of Mines' Society of Physics Students

NASA Astrophysics Data System (ADS)

Moore, Shirley; Stilwell, Matthew; Boerner, Zach

2011-04-01

The Colorado School of Mines (CSM) Society of Physics Students (SPS) revitalized in 2008 and has since blown up with outreach activity, incorporating all age levels into our programs. In Spring 2010, CSM SPS launched a new program called Partners in Physics. Students from Golden High School came to CSM where they had a college-level lesson on standing waves and their applications. These students then joined volunteers from CSM in teaching local elementary school students about standing waves beginning with a science show. The CSM and high school students then helped the children to build make-and-take demonstrations incorporating waves. This year, rockets are the theme for Partners in Physics and we began with demonstrations with local middle school students. In Spring 2011, CSM SPS will be teaching elementary school students about projectile motion and model rockets along with these middle school students. Colorado School of Mines Department of Physics

Hydrological states and the resilience of deltaic forested wetlands

NASA Astrophysics Data System (ADS)

Keim, R.; Allen, S. T.

2017-12-01

The flooding regime constitutes a set of chronic disturbances that are largely responsible for ecosystem structure. However, disturbances do not always constitute stresses to plants that survive because of adaptations to flooded conditions. We examine baldcypress-water tupelo forested wetlands in the delta of the Mississippi River as a case study in mechanisms by which hydrologic change shapes wetland ecosystem change, supported by experimental evidence from remote sensing, tree-ring and other field studies, and meta-analysis across the literature. Decreased hydrologic variability caused by water control structures has reduced the frequency of flood events that increase growth of baldcypress and favor its establishment by reducing competition from other species. Hydrologic modifications that lead to semi-permanent, stagnant flooding constitute semi-permanent disturbance that prevents regeneration of any trees, reduces growth of established trees, and reduces stand density by causing mortality of some trees. However, baldcypress trees in low-density stands appear to be generally adapted for long-term survival in stagnant conditions. Thus, initial decreases in stand density after impoundment do not necessarily portend continued conversion away from forest because reduced inter-tree competition is a negative feedback on mortality. Overall, a natural hydrologic regime with high variability in riverine flooding favors denser stands with greater diversity of tree species, and the present, controlled hydrologic regime that has largely eliminated riverine flooding favors open stands. Sea-level rise will increase salinity that quickly leads to forest conversion to marsh, but will also increase stagnant, freshwater flooding further inland. These drivers of hydrologic change reduce carbon assimilation by forests, both by reduced stand-level productivity and decreased forested area.

Transpiration in an oil palm landscape: effects of palm age

NASA Astrophysics Data System (ADS)

Röll, A.; Niu, F.; Meijide, A.; Hardanto, A.; Hendrayanto; Knohl, A.; Hölscher, D.

2015-06-01

Oil palm (Elaeis guineensis Jacq.) plantations cover large and continuously increasing areas of humid tropical lowlands. Landscapes dominated by oil palms usually consist of a mosaic of mono-cultural, homogeneous stands of varying age, which may be heterogeneous in their water use characteristics. However, studies on the water use characteristics of oil palms are still at an early stage and there is a lack of knowledge on how oil palm expansion will affect the major components of the hydrological cycle. To provide first insights into hydrological landscape-level consequences of oil palm cultivation, we derived transpiration rates of oil palms in stands of varying age, estimated the contribution of palm transpiration to evapotranspiration, and analyzed the influence of fluctuations in environmental variables on oil palm water use. We studied 15 two- to 25 year old stands in the lowlands of Jambi, Indonesia. A sap flux technique with an oil palm specific calibration and sampling scheme was used to derive leaf-, palm- and stand-level water use rates in all stands under comparable environmental conditions. Additionally, in a two- and a 12 year old stand, eddy covariance measurements were conducted to derive evapotranspiration rates. Water use rates per leaf and palm increased 5-fold from an age of two years to a stand age of approx. 10 years and then remained relatively constant. A similar trend was visible, but less pronounced, for estimated stand transpiration rates of oil palms; they varied 12-fold, from 0.2 mm day-1 in a 2 year old to 2.5 mm day-1 in a 12 year old stand, showing particularly high variability in transpiration rates among medium-aged stands. Confronting sap flux and eddy-covariance derived water fluxes suggests that transpiration contributed 8 % to evapotranspiration in the 2 year old stand and 53 % in the 12 year old stand, indicating variable and substantial additional sources of evaporation, e.g. from the soil, the ground vegetation and from trunk epiphytes. Diurnally, oil palm transpiration rates were characterized by an early peak between 10 and 11 a.m.; there was a pronounced hysteresis in the leaf water use response to changes in vapor pressure deficit for all palms of advanced age. On the day-to-day basis this resulted in a relatively low variability of oil palm water use regardless of fluctuations in vapor pressure deficit and radiation. We conclude, that oil palm dominated landscapes show some spatial variations in (evapo)transpiration rates, e.g. due to varying age-structures, but that the temporal variability of oil palm transpiration is rather low. Stand transpiration rates of some studied oil palm stands compared to or even exceed values reported for different tropical forests, indicating a high water use of oil palms under certain site or management conditions. Our study provides first insights into the eco-hydrological characteristics of oil palms as well as a first estimate of oil palm water use across a gradient of plantation age. It sheds first light on some of the hydrological consequences of the continuing expansion of oil palm plantations.

Sapwood temperature gradients between lower stems and the crown do not influence estimates of stand-level stem CO(2) efflux.

PubMed

Bowman, William P; Turnbull, Matthew H; Tissue, David T; Whitehead, David; Griffin, Kevin L

2008-10-01

Temperature plays a critical role in the regulation of respiration rates and is often used to scale measurements of respiration to the stand-level and calculate annual respiratory fluxes. Previous studies have indicated that failure to consider temperature gradients between sun-exposed stems and branches in the crown and shaded lower stems may result in errors when deriving stand-level estimates of stem CO(2) efflux. We measured vertical gradients in sapwood temperature in a mature lowland podocarp rain forest in New Zealand to: (1) estimate the effects of within-stem temperature variation on the vertical distribution of stem CO(2) efflux; and (2) use these findings to estimate stand-level stem CO(2) efflux for this forest. Large within-stem gradients in sapwood temperature (1.6 +/- 0.1 to 6.0 +/- 0.5 degrees C) were observed. However, these gradients did not significantly influence the stand-level estimate of stem CO(2) efflux in this forest (536 +/- 42 mol CO(2) ha(-1) day(-1)) or the vertical distribution of stem CO(2) efflux, because of the opposing effects of daytime warming and nighttime cooling on CO(2) efflux in the canopy, and the small fraction of the woody biomass in the crowns of forest trees. Our findings suggest that detailed measurements of within-stand temperature gradients are unlikely to greatly improve the accuracy of tree- or stand-level estimates of stem CO(2) efflux.

7. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. ...

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

7. CABLE RACK, MEZZANINE LEVEL, INTERIOR OF TEST STAND 1A. Looking north from north end of the cable tunnel leading toward Control Center. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

High-efficiency particulate air filter test stand and aerosol generator for particle loading studies

NASA Astrophysics Data System (ADS)

Arunkumar, R.; Hogancamp, Kristina U.; Parsons, Michael S.; Rogers, Donna M.; Norton, Olin P.; Nagel, Brian A.; Alderman, Steven L.; Waggoner, Charles A.

2007-08-01

This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30×30×29cm3 nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5to12standardm3/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150°C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7standardm3/min, high mass concentrations (˜25mg/m3) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

High-efficiency particulate air filter test stand and aerosol generator for particle loading studies.

PubMed

Arunkumar, R; Hogancamp, Kristina U; Parsons, Michael S; Rogers, Donna M; Norton, Olin P; Nagel, Brian A; Alderman, Steven L; Waggoner, Charles A

2007-08-01

This manuscript describes the design, characterization, and operational range of a test stand and high-output aerosol generator developed to evaluate the performance of 30 x 30 x 29 cm(3) nuclear grade high-efficiency particulate air (HEPA) filters under variable, highly controlled conditions. The test stand system is operable at volumetric flow rates ranging from 1.5 to 12 standard m(3)/min. Relative humidity levels are controllable from 5%-90% and the temperature of the aerosol stream is variable from ambient to 150 degrees C. Test aerosols are produced through spray drying source material solutions that are introduced into a heated stainless steel evaporation chamber through an air-atomizing nozzle. Regulation of the particle size distribution of the aerosol challenge is achieved by varying source solution concentrations and through the use of a postgeneration cyclone. The aerosol generation system is unique in that it facilitates the testing of standard HEPA filters at and beyond rated media velocities by consistently providing, into a nominal flow of 7 standard m(3)/min, high mass concentrations (approximately 25 mg/m(3)) of dry aerosol streams having count mean diameters centered near the most penetrating particle size for HEPA filters (120-160 nm). Aerosol streams that have been generated and characterized include those derived from various concentrations of KCl, NaCl, and sucrose solutions. Additionally, a water insoluble aerosol stream in which the solid component is predominantly iron (III) has been produced. Multiple ports are available on the test stand for making simultaneous aerosol measurements upstream and downstream of the test filter. Types of filter performance related studies that can be performed using this test stand system include filter lifetime studies, filtering efficiency testing, media velocity testing, evaluations under high mass loading and high humidity conditions, and determination of the downstream particle size distributions.

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment.

PubMed

Oliveira, Steffan Edward Octávio; Costa, Cíntia Carol de Melo; de Souza, João Batista Freire; de Queiroz, João Paulo Araújo Fernandes; Maia, Alex Sandro Campos; Costa, Leonardo Lelis de Macedo

2014-12-01

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R S-W, W m(-2)), were recorded. The R S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R S-W remained below 500 W m(-2). The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m(-2), the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R S-W exceeded 700 W m(-2). The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R S-W were recorded (815 and 958 W m(-2), respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m(-2).

Tree Mortality

Treesearch

Mark J. Ambrose

2011-01-01

Tree mortality is a natural process in all forest ecosystems, but it can also be an indicator of forest health issues. On a regional scale, high-mortality levels may indicate widespread insect or disease problems. Regionally high mortality may also occur if a large proportion of the forests in an area are made up of older, senescent stands.

Seasonal Lateral Root Growth of Juvenile Loblolly Pine After Thinning and Fertilization on Gulf Coastal Plain Site

Treesearch

Mary Anne Sword; James D. Haywood; C. Dan Andries

1998-01-01

In 1989, two levels each of stand density and fertilization were factorially established in an 8-year-old loblolly pine plantation on a P-deficient site. Levels of stand density were nonthinned at 2,732 trees per hectare and thinned at 721 trees per hectare. Fertilizer levels were none or application of 150 kilograms P plus 135 kilograms N per hectare. In 1994, stand...

Detection of forest stand-level spatial structure in ectomycorrhizal fungal communities.

PubMed

Lilleskov, Erik A; Bruns, Thomas D; Horton, Thomas R; Taylor, D; Grogan, Paul

2004-08-01

Ectomycorrhizal fungal (EMF) communities are highly diverse at the stand level. To begin to understand what might lead to such diversity, and to improve sampling designs, we investigated the spatial structure of these communities. We used EMF community data from a number of studies carried out in seven mature and one recently fire-initiated forest stand. We applied various measures of spatial pattern to characterize distributions at EMF community and species levels: Mantel tests, Mantel correlograms, variance/mean and standardized variograms. Mantel tests indicated that in four of eight sites community similarity decreased with distance, whereas Mantel correlograms also found spatial autocorrelation in those four plus two additional sites. In all but one of these sites elevated similarity was evident only at relatively small spatial scales (< 2.6 m), whereas one exhibited a larger scale pattern ( approximately 25 m). Evenness of biomass distribution among cores varied widely among taxa. Standardized variograms indicated that most of the dominant taxa showed patchiness at a scale of less than 3 m, with a range from 0 to < or =17 m. These results have implications for both sampling scale and intensity to achieve maximum efficiency of community sampling. In the systems we examined, cores should be at least 3 m apart to achieve the greatest sampling efficiency for stand-level community analysis. In some cases even this spacing may result in reduced sampling efficiency arising from patterns of spatial autocorrelation. Interpretation of the causes and significance of these patterns requires information on the genetic identity of individuals in the communities.

Tsunami deposits at MIS Stages 5e and 9 on Oahu, Hawaii: implications for sea level at interglacial stages

NASA Astrophysics Data System (ADS)

McMurtry, G. M.; Campbell, J. F.; Fryer, G. J.; Tappin, D. R.; Fietzke, J.

2010-12-01

Sandy, basalt-coral conglomerates associated with both beachrock and coral reefs are found at high elevations on Oahu, Hawaii. They have been attributed to either brief, sea level high-stands or storms. The Kahe Point conglomerates are at 12.5 m elevation, whereas the main stage MIS-5e reef at this location has a maximum elevation of 8.2 m. They are loosely consolidated and poorly cemented, graded, poorly sorted, and with varying amounts of basalt and coral clasts ranging from cobble to boulder size. Coral in these deposits has been U-series dated by us at between 120-125 ka (n=5). Four distinct beds, with a gently seaward tilt, are recognized in a road cut section, with each bed composed of a few cm-thick topset bed of fine-grained, shelly, calcareous sand to silt. Similar high elevation conglomerates and 5e reefs are also described at Mokapu and Kaena Points on Oahu, indicating an island-wide deposit. Older coral clasts, dated at 130 to 142 ka (n=6; oldest by alpha spectrometry) found in association with the stage 5e corals suggest reworking and incorporation of older low-stand reef material. The coarse grain size of the conglomerates indicates deposition from a high-energy event; thus a high-stand source is ruled out. We also consider that the overall lithology and up to 0.5 m bed thickness not to be the result of storms; a series of high frequency storm events is considered unlikely. The weight of the evidence in our opinion clearly indicates deposition by a series of tsunami waves. If correct, this has implications for “probabilistic” models of sea level peaks at least 6.6 m higher than present at stage 5e that use such data in their models (e. g., Kopp et al., 2009), at least for Oahu. Within about 2 km of the Kahe deposit, in a road cut at Ko Olina, there is another markedly similar high-energy, sandy basalt-bearing coral conglomerate sequence at 21 to 25 m elevation. There are at least two distinct beds about one meter in thickness, both gently seaward tilting and with bed layer containing a few cm-thick topset of fine, shelly, calcareous sand to silt. The sediments are loosely consolidated and poorly cemented, graded, moderately sorted, with coral clasts ranging from pebble to boulder size, predominately cobble. Compared to the deposits at Kahe, those at Ko Olina are more heavily dominated by rounded coral clasts that are U-series dated at between 302-363 ka (n=5); broadly correlative with MIS stage 9. Previously described as a high-stand reef deposit, we suggest it is more likely to be a tsunami deposit too; perhaps considering its’ elevation, laid down from a mega-tsunami, if it was deposited prior to the MIS stage 9 high-stand at approximately 325 ka.

Added Value of Physical Performance Measures in Predicting Adverse Health-Related Events: Results from the Health, Aging, and Body Composition Study

PubMed Central

Cesari, Matteo; Kritchevsky, Stephen B; Newman, Anne B; Simonsick, Eleanor M; Harris, Tamara B; Penninx, Brenda W; Brach, Jennifer S; Tylavsky, Frances A; Satterfield, Suzanne; Bauer, Doug C; Rubin, Susan M; Visser, Marjolein; Pahor, Marco

2009-01-01

Objectives To determine how three different physical performance measures (PPM) combine for added utility in predicting adverse health events in elders. Design Prospective cohort study. Setting Health, Aging, and Body Composition Study. Participants 3,024 well-functioning older persons (mean age 73.6 years). Measurements Timed gait, repeated chair stands and balance (semi- and full-tandem, and single leg stands each held for 30 seconds) tests were administered at baseline. Usual gait speed was categorized to distinguish high and low risk participants using the previously established 1 m/sec cut-point. The same population-percentile (21.3%) was used to identify cut-points for repeated chair stands (17.05 sec) and balance (53 sec) tests. Cox proportional hazard analyses were performed to evaluate the added value of PPM in predicting mortality, hospitalization, and (severe) mobility limitation events over 6.9 years of follow-up. Results Risk estimates for developing adverse health-related events were similarly large for each of the three high risk groups considered separately. A greater number of PPM scores at the high risk level was associated with a greater risk of developing adverse health-related events. When all three PPMs were considered, having only one poor performance was sufficient to indicate a highly significant higher risk of (severe) lower extremity and mortality events. Conclusion Although gait speed is considered the most important predictor of adverse health events, these findings demonstrate that poor performance on other tests of lower extremity function are equally prognostic. This suggests that chair stand and standing balance performance may be adequate substitutes when gait speed is unavailable. PMID:19207142

Analysing Amazonian forest productivity using a new individual and trait-based model (TFS v.1)

NASA Astrophysics Data System (ADS)

Fyllas, N. M.; Gloor, E.; Mercado, L. M.; Sitch, S.; Quesada, C. A.; Domingues, T. F.; Galbraith, D. R.; Torre-Lezama, A.; Vilanova, E.; Ramírez-Angulo, H.; Higuchi, N.; Neill, D. A.; Silveira, M.; Ferreira, L.; Aymard C., G. A.; Malhi, Y.; Phillips, O. L.; Lloyd, J.

2014-07-01

Repeated long-term censuses have revealed large-scale spatial patterns in Amazon basin forest structure and dynamism, with some forests in the west of the basin having up to a twice as high rate of aboveground biomass production and tree recruitment as forests in the east. Possible causes for this variation could be the climatic and edaphic gradients across the basin and/or the spatial distribution of tree species composition. To help understand causes of this variation a new individual-based model of tropical forest growth, designed to take full advantage of the forest census data available from the Amazonian Forest Inventory Network (RAINFOR), has been developed. The model allows for within-stand variations in tree size distribution and key functional traits and between-stand differences in climate and soil physical and chemical properties. It runs at the stand level with four functional traits - leaf dry mass per area (Ma), leaf nitrogen (NL) and phosphorus (PL) content and wood density (DW) varying from tree to tree - in a way that replicates the observed continua found within each stand. We first applied the model to validate canopy-level water fluxes at three eddy covariance flux measurement sites. For all three sites the canopy-level water fluxes were adequately simulated. We then applied the model at seven plots, where intensive measurements of carbon allocation are available. Tree-by-tree multi-annual growth rates generally agreed well with observations for small trees, but with deviations identified for larger trees. At the stand level, simulations at 40 plots were used to explore the influence of climate and soil nutrient availability on the gross (ΠG) and net (ΠN) primary production rates as well as the carbon use efficiency (CU). Simulated ΠG, ΠN and CU were not associated with temperature. On the other hand, all three measures of stand level productivity were positively related to both mean annual precipitation and soil nutrient status. Sensitivity studies showed a clear importance of an accurate parameterisation of within- and between-stand trait variability on the fidelity of model predictions. For example, when functional tree diversity was not included in the model (i.e. with just a single plant functional type with mean basin-wide trait values) the predictive ability of the model was reduced. This was also the case when basin-wide (as opposed to site-specific) trait distributions were applied within each stand. We conclude that models of tropical forest carbon, energy and water cycling should strive to accurately represent observed variations in functionally important traits across the range of relevant scales.

Using stand-level optimization to reduce crown fire hazard

Treesearch

David H. Graetz; John Sessions; Steven L. Garman

2007-01-01

This study evaluated the ability to generate prescriptions for a wide variety of stands when the goal is to reduce crown fire potential. Forest managers charged with reducing crown fire potential while providing for commodity and ecological production have been hampered by the complexity of possible management options. A program called Stand-Level Optimization with...

Spatial variation of fuel loading within varying aged stands of chaparral

Treesearch

Kellie A. Uyeda; Douglas A. Stow; John F. O' Leary; Ian T. Schmidt; Philip J. Riggan

2016-01-01

Questions: How do stand-level biomass and percentage of deadmaterial in chaparral vary as a function of stand age? How do the landscape properties of aggregation index and patch size vary in each of the dominant species groups as a function of stand age? Location: Stands of 7-, 28-and 68-yr-old...

Changing stand structure and regional growth reductions in Georgia's natural pine stands

Treesearch

W.A. Bechtold; G.A. Ruark; F.T. Lloyd

1991-01-01

Forest Inventory and Analysis (FIA) data indicate reductions in the growth of naturally regenerated pines in Georgia between the two latest measurement periods (1961-1972 vs. 1972-1982). Analysis of Covariance was used to adjust stand-level basal area growth rates for differences between periods in stand age, stand density, site index, mortality, and hardwood...

B-1 and B-3 Test Stands at NASA’s Plum Brook Station

NASA Image and Video Library

1966-09-21

Operation of the High Energy Rocket Engine Research Facility (B-1), left, and Nuclear Rocket Dynamics and Control Facility (B-3) at the National Aeronautics and Space Administration’s (NASA) Plum Brook Station in Sandusky, Ohio. The test stands were constructed in the early 1960s to test full-scale liquid hydrogen fuel systems in simulated altitude conditions. Over the next decade each stand was used for two major series of liquid hydrogen rocket tests: the Nuclear Engine for Rocket Vehicle Application (NERVA) and the Centaur second-stage rocket program. The different components of these rocket engines could be studied under flight conditions and adjusted without having to fire the engine. Once the preliminary studies were complete, the entire engine could be fired in larger facilities. The test stands were vertical towers with cryogenic fuel and steam ejector systems. B-1 was 135 feet tall, and B-3 was 210 feet tall. Each test stand had several levels, a test section, and ground floor shop areas. The test stands relied on an array of support buildings to conduct their tests, including a control building, steam exhaust system, and fuel storage and pumping facilities. A large steam-powered altitude exhaust system reduced the pressure at the exhaust nozzle exit of each test stand. This allowed B-1 and B-3 to test turbopump performance in conditions that matched the altitudes of space.

Chapter 13: Interannual Differences in Detections of Marbled Murrelets in Some Inland California Stands

Treesearch

C. John Ralph

1995-01-01

I compared the mean level of detections of Marbled Murrelets by month over five years at three inland sites in northern California. These areas all have relatively high levels of detections. There were no significant differences in mean detection levels year to year at any site, and for any month with the exception of April at one site. This lack of evidence for...

13C-isotopic fingerprint of Pinus pinaster Ait. and Pinus sylvestris L. wood related to the quality of standing tree mass in forests from NW Spain.

PubMed

Fernandez, Irene; González-Prieto, Serafin J; Cabaneiro, Ana

2005-01-01

Pine forest plantations of Pinus pinaster Ait. and P. sylvestris L. located in Galicia, NW Spain, were selected to study the 13C/12C-isotopic fingerprint in wood core samples in order to find possible relationships between the delta(13)C at natural abundance levels and the quality of the standing tree mass. For each pine species, 24 forests growing on acidic soils were studied: half developed over granite and half over schists. Two dominant trees from each plot, corresponding to all possible combinations of forest stands with high or low site index and with adults or young trees, were drilled at the basal part of trunks using a Pressler drill to obtain tree ring samples. The C-isotopic compositions of the litter and the soil organic matter from different soil depths were also determined and statistically significant correlations between these values and the 13C content of the wood were observed. Despite internal variations due to the influence of site index, tree age and parent material, the isotopic fingerprint of P. pinaster wood (mean value delta13C=-26.2+/-0.8 per thousand) significantly differed (P<0.001) from that of P. sylvestris (mean value delta13C=-24.6+/-0.7 per thousand). Relationships between the quality of the stand and the C-isotopic composition of the wood were observed, high quality stands having trees more 13C-depleted than low quality ones. A high correlation between wood delta13C and site index values for P. pinaster stands (r=-0.667, P<0.001) was found, this correlation being even clearer when only P. pinaster growing over schists (r=-0.833, P<0.001) are considered. Again, the correlation between the site index and the wood delta13C of young P. pinaster trees is higher when plots over granite or schists are separately considered. A similar fact occurs for adult P. sylvestris trees from schists stands, high quality specimens being 13C-depleted compared with low quality ones. On the other hand, 13C natural abundance of wood from P. sylvestris trees seems to be also strongly influenced by the underlying parent material, young trees from granite stands having a statistically higher 13C-isotopic composition (P<0.05) than young trees from schists stands. Copyright (c) 2005 John Wiley & Sons, Ltd.

Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners.

PubMed

Batterman, S; Du, L; Mentz, G; Mukherjee, B; Parker, E; Godwin, C; Chin, J-Y; O'Toole, A; Robins, T; Rowe, Z; Lewis, T

2012-06-01

This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84±27%, but dropped to 63±33% in subsequent seasons. In months when households were not visited, use averaged only 34±30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. Environmental tobacco smoke (ETS) increased particulate matter (PM) levels by about 14 μg/m3 and was often detected using ETS-specific tracers despite restrictions on smoking in the house as reported on questionnaires administered to caregivers. PM concentrations depended on season, filter usage, relative humidity, air exchange ratios, number of children, outdoor PM levels, sweeping/dusting, and presence of a central air conditioner (AC). Free-standing air filters can be an effective intervention that provides substantial reductions in PM concentrations if the filters are used. However, filter use was variable across the study population and declined over the study duration, and thus strategies are needed to encourage and maintain use of filters. The variability in filter use suggests that exposure misclassification is a potential problem in intervention studies using filters. The installation of a room AC in the bedroom, intended to limit air exchange ratios, along with an air filter, did not lower PM levels more than the filter alone. © 2011 John Wiley & Sons A/S.

A Linked Model for Simulating Stand Development and Growth Processes of Loblolly Pine

Treesearch

V. Clark Baldwin; Phillip M. Dougherty; Harold E. Burkhart

1998-01-01

Linking models of different scales (e.g., process, tree-stand-ecosystem) is essential for furthering our understanding of stand, climatic, and edaphic effects on tree growth and forest productivity. Moreover, linking existing models that differ in scale and levels of resolution quickly identifies knowledge gaps in information required to scale from one level to another...

Fuel treatment effects on modeled landscape level fire behavior in the northern Sierra Nevada

Treesearch

J.J. Moghaddas; B.M. Collins; K. Menning; E.E.Y. Moghaddas; S.L. Stephens

2010-01-01

Across the western United States, decades of fire exclusion combined with past management history have contributed to the current condition of extensive areas of high-density, shade-tolerant coniferous stands that are increasingly prone to high-severity fires. Here, we report the modeled effects of constructed defensible fuel profile zones and group selection...

Ponderosa pine forest restoration treatment longevity: Implications of regeneration on fire hazard

Treesearch

Wade T. Tinkham; Chad M. Hoffman; Seth A. Ex; Michael A. Battaglia; Jarred D. Saralecos

2016-01-01

Restoration of pine forests has become a priority for managers who are beginning to embrace ideas of highly heterogeneous forest structures that potentially encourages high levels of regeneration. This study utilizes stem-mapped stands to assess how simulated regeneration timing and magnitude influence longevity of reduced fire behavior by linking growth and...

Changing Schools: A Look at Student Mobility Trends in Chicago Public Schools Since 1995

ERIC Educational Resources Information Center

de la Torre, Marisa; Gwynne, Julia

2009-01-01

Student mobility has been a long-standing concern to educators and researchers because of the negative impact that changing schools can have on students, teachers, and schools. High levels of student mobility can create a sense of upheaval and constant change at the school level, and schools typically have few established practices in place to…

Design Notebook for Naval Air Defense Simulation (NADS). Special Programs.

DTIC Science & Technology

1982-09-15

provides high level decision making and coordination among the elements of the defending force. A more detailed description of the command center...loiter, cruise, normal intercept, and high speed intercept. Appropriate fuel consumption rates are used for each speed. When on CAP station the...Stand-Off Jammer Aircraft SW aircraft carry high power electronic transmitting equipment capable of jaimming radars and communication channels from

Using SO2 camera imagery and seismicity to examine degassing and gas accumulation at Kīlauea Volcano, May 2010

USGS Publications Warehouse

Nadeau, Patricia A; Werner, Cynthia A.; Waite, Gregory P.; Carn, Simon A; Brewer, Ian D; Elias, Tamar; Sutton, Andrew; Kern, Christoph

2015-01-01

SO2 camera measurements at Kīlauea Volcano, Hawaii, in May of 2010 captured two occurrences of lava lake rise and fall within the Halema'um'au Crater summit vent. During high lava stands we observed diminished SO2 emission rates and decreased seismic tremor. Similar events at Kīlauea have been described as the result of sporadic degassing following gas accumulation beneath a mostly impermeable lava lake surface. Incorporation of SO2 camera data into a multi-parameter dataset gives credence to the likelihood of shallow gas accumulation as the cause of these high stand events, with accumulated gas release upon lake-level drop compensating for the gas deficit reached during accumulation.

Verification of Spent Nuclear Fuel in Sealed Dry Storage Casks via Measurements of Cosmic-Ray Muon Scattering

NASA Astrophysics Data System (ADS)

Durham, J. M.; Poulson, D.; Bacon, J.; Chichester, D. L.; Guardincerri, E.; Morris, C. L.; Plaud-Ramos, K.; Schwendiman, W.; Tolman, J. D.; Winston, P.

2018-04-01

Most of the plutonium in the world resides inside spent nuclear reactor fuel rods. This high-level radioactive waste is commonly held in long-term storage within large, heavily shielded casks. Currently, international nuclear safeguards inspectors have no stand-alone method of verifying the amount of reactor fuel stored within a sealed cask. Here we demonstrate experimentally that measurements of the scattering angles of cosmic-ray muons, which pass through a storage cask, can be used to determine if spent fuel assemblies are missing without opening the cask. This application of technology and methods commonly used in high-energy particle physics provides a potential solution to this long-standing problem in international nuclear safeguards.

Stand quality management in a late-rotation, red oak-sweetgum stand in east Mississippi: preliminary results following thinning

Treesearch

James S. Meadows; Daniel A. Skojac

2012-01-01

Stand quality management is a new management strategy in which thinning prescriptions are based solely on tree quality rather than a quantitative level of residual stand density. As long as residual density falls within fairly broad limits, prescriptions are based on tree quality alone. We applied four thinning prescriptions based on stand quality management, along...

Electrospun N-Doped Porous Carbon Nanofibers Incorporated with NiO Nanoparticles as Free-Standing Film Electrodes for High-Performance Supercapacitors and CO2 Capture.

PubMed

Li, Qi; Guo, Jiangna; Xu, Dan; Guo, Jianqiang; Ou, Xu; Hu, Yin; Qi, Haojun; Yan, Feng

2018-04-01

Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition-metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle-dispersed electrospun N-doped porous CNF (NiO/PCNF) and as free-standing film electrode for high-performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N-doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free-standing NiO/PCNF electrodes show a high specific capacitance of 850 F g -1 at a current density of 1 A g -1 in 6 m KOH aqueous solution, good rate capability, as well as excellent long-term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO 2 uptake, and high-efficiency CO 2 electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high-performance supercapacitors and CO 2 electroreduction. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

FAST TRACK COMMUNICATION: An electromagnetically induced grating by microwave modulation

NASA Astrophysics Data System (ADS)

Xiao, Zhi-Hong; Shin, Sung Guk; Kim, Kisik

2010-08-01

We study the phenomenon of an electromagnetically induced phase grating in a double-dark state system of 87Rb atoms, the two closely placed lower fold levels of which are coupled by a weak microwave field. Owing to the existence of the weak microwave field, the efficiency of the phase grating is strikingly improved, and an efficiency of approximately 33% can be achieved. Under the action of the weak standing wave field, the high efficiency of the phase grating can be maintained by modulating the strength and detuning of the weak microwave field, increasing the strength of the standing wave field.

Benchmarking the Collocation Stand-Alone Library and Toolkit (CSALT)

NASA Technical Reports Server (NTRS)

Hughes, Steven; Knittel, Jeremy; Shoan, Wendy; Kim, Youngkwang; Conway, Claire; Conway, Darrel J.

2017-01-01

This paper describes the processes and results of Verification and Validation (VV) efforts for the Collocation Stand Alone Library and Toolkit (CSALT). We describe the test program and environments, the tools used for independent test data, and comparison results. The VV effort employs classical problems with known analytic solutions, solutions from other available software tools, and comparisons to benchmarking data available in the public literature. Presenting all test results are beyond the scope of a single paper. Here we present high-level test results for a broad range of problems, and detailed comparisons for selected problems.

Benchmarking the Collocation Stand-Alone Library and Toolkit (CSALT)

NASA Technical Reports Server (NTRS)

Hughes, Steven; Knittel, Jeremy; Shoan, Wendy (Compiler); Kim, Youngkwang; Conway, Claire (Compiler); Conway, Darrel

2017-01-01

This paper describes the processes and results of Verification and Validation (V&V) efforts for the Collocation Stand Alone Library and Toolkit (CSALT). We describe the test program and environments, the tools used for independent test data, and comparison results. The V&V effort employs classical problems with known analytic solutions, solutions from other available software tools, and comparisons to benchmarking data available in the public literature. Presenting all test results are beyond the scope of a single paper. Here we present high-level test results for a broad range of problems, and detailed comparisons for selected problems.

Are self-thinning constraints needed in a tree-specific mortality model?

Treesearch

Robert A. Monserud; Thomas Ledermann; Hubert Sterba

2005-01-01

Can a tree-specific mortality model elicit expected forest stand density dynamics without imposing stand-level constraints such as Reineke's maximum stand density index (SDImax) or the -3/2 power law of self-thinning? We examine this emergent properties question using the Austrian stand simulator PROGNAUS. This simulator was chosen...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2010 CFR

2010-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

Stand density relationships

Treesearch

John C. Tappeiner

2013-01-01

Th inning stands (managing their densities) aff ects the development of trees and understory plants as individuals, as well as stand-level characteristics like structure, microclimate, and stand growth, habitat for various species, and fuel and potential fi re severity. Th ese characteristics and the rate of changes are aff ected by thinning severity—the reduction in...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2013 CFR

2013-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2012 CFR

2012-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2014 CFR

2014-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

49 CFR 210.33 - Operation standards (switcher locomotives, load cell test stands, car coupling operations, and...

Code of Federal Regulations, 2011 CFR

2011-10-01

... cell test stands, car coupling operations, and retarders). 210.33 Section 210.33 Transportation Other... (switcher locomotives, load cell test stands, car coupling operations, and retarders). (a) Measurement on receiving property of the noise emission levels from switcher locomotives, load cell test stands, car...

Esthetics evaluation

Treesearch

Victor A. Rudis; James H. Gramann; Theresa A. Herrick

1994-01-01

An analysis of summer visual attributes and an overview of ongoing scenic quality research within selected shortleaf pine-hardwood stands in the Ouachita and Ozark National forests are presented.Within-stand visual attributes were reported prior to even-aged stand-level (Phase II) treatment for twelve 40-acre stands in the north, east, and south regions and for plot-...

Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners

PubMed Central

Batterman, S.; Du, L.; Mentz, G.; Mukherjee, B.; Parker, E.; Godwin, C.; Chin, J.-Y.; O'Toole, A.; Robins, T.; Rowe, Z.; Lewis, T.

2014-01-01

This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84 ± 27%, but dropped to 63 ± 33% in subsequent seasons. In months when households were not visited, use averaged only 34 ± 30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. PMID:22145709

Reinvasion of Hardwoods Following Eradication in an Unveven-Aged Pine Stand

Treesearch

M.D. Cain; D.A. Yaussy

1983-01-01

Study quantitatively describes the woody plant component that developed in an uneven-aged loblolly/shortleaf pine stand following hardwood eradication. Comparisons are made with four other stands managed at various intensity levels.

Spatial and thematic assessment of object-based forest stand delineation using an OFA-matrix

NASA Astrophysics Data System (ADS)

Hernando, A.; Tiede, D.; Albrecht, F.; Lang, S.

2012-10-01

The delineation and classification of forest stands is a crucial aspect of forest management. Object-based image analysis (OBIA) can be used to produce detailed maps of forest stands from either orthophotos or very high resolution satellite imagery. However, measures are then required for evaluating and quantifying both the spatial and thematic accuracy of the OBIA output. In this paper we present an approach for delineating forest stands and a new Object Fate Analysis (OFA) matrix for accuracy assessment. A two-level object-based orthophoto analysis was first carried out to delineate stands on the Dehesa Boyal public land in central Spain (Avila Province). Two structural features were first created for use in class modelling, enabling good differentiation between stands: a relational tree cover cluster feature, and an arithmetic ratio shadow/tree feature. We then extended the OFA comparison approach with an OFA-matrix to enable concurrent validation of thematic and spatial accuracies. Its diagonal shows the proportion of spatial and thematic coincidence between a reference data and the corresponding classification. New parameters for Spatial Thematic Loyalty (STL), Spatial Thematic Loyalty Overall (STLOVERALL) and Maximal Interfering Object (MIO) are introduced to summarise the OFA-matrix accuracy assessment. A stands map generated by OBIA (classification data) was compared with a map of the same area produced from photo interpretation and field data (reference data). In our example the OFA-matrix results indicate good spatial and thematic accuracies (>65%) for all stand classes except for the shrub stands (31.8%), and a good STLOVERALL (69.8%). The OFA-matrix has therefore been shown to be a valid tool for OBIA accuracy assessment.

Postural control during quiet bipedal standing in rats

PubMed Central

Sato, Yota; Fujiki, Soichiro; Sato, Yamato; Aoi, Shinya; Tsuchiya, Kazuo; Yanagihara, Dai

2017-01-01

The control of bipedal posture in humans is subject to non-ideal conditions such as delayed sensation and heartbeat noise. However, the controller achieves a high level of functionality by utilizing body dynamics dexterously. In order to elucidate the neural mechanism responsible for postural control, the present study made use of an experimental setup involving rats because they have more accessible neural structures. The experimental design requires rats to stand bipedally in order to obtain a water reward placed in a water supplier above them. Their motions can be measured in detail using a motion capture system and a force plate. Rats have the ability to stand bipedally for long durations (over 200 s), allowing for the construction of an experimental environment in which the steady standing motion of rats could be measured. The characteristics of the measured motion were evaluated based on aspects of the rats’ intersegmental coordination and power spectrum density (PSD). These characteristics were compared with those of the human bipedal posture. The intersegmental coordination of the standing rats included two components that were similar to that of standing humans: center of mass and trunk motion. The rats’ PSD showed a peak at approximately 1.8 Hz and the pattern of the PSD under the peak frequency was similar to that of the human PSD. However, the frequencies were five times higher in rats than in humans. Based on the analysis of the rats’ bipedal standing motion, there were some common characteristics between rat and human standing motions. Thus, using standing rats is expected to be a powerful tool to reveal the neural basis of postural control. PMID:29244818

Individual tree- versus stand-level approaches to thinning: is it a choice of one or the other, or a combination of both?

Treesearch

Christopher A. Nowak

1995-01-01

Thinning guidelines have existed for most eastern hardwood forests for 20 to 30 years. While these guidelines are presented in varying degrees of detail, they generally all contain recommendations on levels of residual stand density and stand structure, along with information on crop tree requirements. Recent attempts have been made to simplify thinning guidelines by...

Predicting breeding bird occurrence by stand- and microhabitat-scale features in even-aged stands in the Central Appalachians

USGS Publications Warehouse

McDermott, M.E.; Wood, P.B.; Miller, G.W.; Simpson, B.T.

2011-01-01

Spatial scale is an important consideration when managing forest wildlife habitat, and models can be used to improve our understanding of these habitats at relevant scales. Our objectives were to determine whether stand- or microhabitat-scale variables better predicted bird metrics (diversity, species presence, and abundance) and to examine breeding bird response to clearcut size and age in a highly forested landscape. In 2004-2007, vegetation data were collected from 62 even-aged stands that were 3.6-34.6. ha in size and harvested in 1963-1990 on the Monongahela National Forest, WV, USA. In 2005-2007, we also surveyed birds at vegetation plots. We used classification and regression trees to model breeding bird habitat use with a suite of stand and microhabitat variables. Among stand variables, elevation, stand age, and stand size were most commonly retained as important variables in guild and species models. Among microhabitat variables, medium-sized tree density and tree species diversity most commonly predicted bird presence or abundance. Early successional and generalist bird presence, abundance, and diversity were better predicted by microhabitat variables than stand variables. Thus, more intensive field sampling may be required to predict habitat use for these species, and management may be needed at a finer scale. Conversely, stand-level variables had greater utility in predicting late-successional species occurrence and abundance; thus management decisions and modeling at this scale may be suitable in areas with a uniform landscape, such as our study area. Our study suggests that late-successional breeding bird diversity can be maximized long-term by including harvests >10. ha in size into our study area and by increasing tree diversity. Some harvesting will need to be incorporated regularly, because after 15 years, the study stands did not provide habitat for most early successional breeding specialists. ?? 2010 Elsevier B.V.

Predicting plot basal area and tree density in mixed-conifer forest from lidar and Advanced Land Imager (ALI) data

Treesearch

Andrew T. Hudak; Jeffrey S. Evans; Michael J. Falkowski; Nicholas L. Crookston; Paul E. Gessler; Penelope Morgan; Alistair M. S. Smith

2005-01-01

Multispectral satellite imagery are appealing for their relatively low cost, and have demonstrated utility at the landscape level, but are typically limited at the stand level by coarse resolution and insensitivity to variation in vertical canopy structure. In contrast, lidar data are less affected by these difficulties, and provide high structural detail, but are less...

Suggested stocking levels for forest stands in northeastern Oregon and southeastern Washington.

Treesearch

P.H. Cochran; J.M. Geist; D.L. Clemens; Rodrick R. Clausnitzer; David C. Powell

1993-01-01

Catastrophes and manipulation of stocking levels are important determinants of stand development and the appearance of future forest landscapes. Managers need stocking level guides, particularly for sites incapable of supporting stocking levels presented in normal yield tables. Growth basal area (GBA) has been used by some managers in attempts to assess inherent...

Water and Energy Balances of Loblolly Pine Plantation Forests during a Full Stand Rotation

NASA Astrophysics Data System (ADS)

Sun, G.; Mitra, B.; Domec, J. C.; Gavazi, M.; Yang, Y.; Tian, S.; Zietlow, D.; McNulty, S.; King, J.; Noormets, A.

2017-12-01

Loblolly pine (Pinus taeda) plantations in the southern U.S. are well recognized for their ecosystem services in supplying clean and stable water and mitigating climate change through carbon sequestration and solar energy partitioning. Since 2004, we have monitored energy, water, and carbon fluxes in a chronosequence of three drained loblolly pine plantations using integrated methods that include eddy covariance, sap flux, watershed hydrometeorology, remote sensing, and process-based simulation modeling. Study sites were located on the eastern North Carolina coastal plain, representing highly productive ecosystems with high groundwater table, and designated in the Ameriflux network as NC1 (0-10 year old), NC2 (12-25 year old) and NC3 (0-3 years old). The 13-year study spanned a wide range of annual precipitation (900-1600 mm/yr) including two exceptionally dry years during 2007-2008. We found that the mature stand (NC2) had higher net radiation (Rn) flux due to its lower albedo (α =0.11-12), compared with the young stands (NC1, NC3) (α=0.15-0.18). Annually about 75%-80% of net radiation was converted to latent heat in the pine plantations. In general, the mature stand had higher latent heat flux (LE) (i.e. evapotranspiration (ET)) rates than the young stands, but ET rates were similar during wet years when the groundwater table was at or near the soil surface. During a historic drought period (i.e., 2007-2008), total stand annual ET exceeded precipitation, but decreased about 30% at NC2 when compared to a normal year (e.g., 2006). Field measurements and remote sensing-based modeling suggested that annual ET rates increased linearly from planting age (about 800 mm) to age 15 (about 1050 mm) and then stabilized as stand leaf area index leveled-off. Over a full stand rotation, approximately 70% (young stand) to 90% (mature stand) of precipitation was returned to the atmosphere through ET. We conclude that both climatic variability and canopy structure controlled the partitioning of precipitation and solar energy in pine forests. In addition, we conclude that accessible groundwater was important factor for stabilizing forest water and energy balances during a drought in the lower coastal ecosystems.

Thinning ponderosa pine (Pinus ponderosa) stands reduces mortality while maintaining stand productivity

Treesearch

Jianwei Zhang; Martin W. Ritchie; Douglas A. Maguire; William W. Oliver

2013-01-01

We analyzed 45-yr data collected from three ponderosa pine (Pinus ponderosa Lawson & C. Lawson) levels-of-growing-stock installations in Oregon (OR) and northern California (CA), USA, to determine the effect of stand density regimes on stand productivity and mortality. We found that periodic annual increment (PAI) of diameter, basal area (BA...

Are self-thinning contraints needed in a tree-specific mortality model.

Treesearch

Robert A. Monserud; Thomas Ledermann; Hubert Sterba

2005-01-01

Can a tree-specific mortality model elicit expected forest stand density dynamics without imposing stand-level constraints such as Reineke's maximum stand density index (SDI,) or the -312 power law of self-thinning? We examine this emergent properties question using the Austrian stand simulator PROGNAUS. This simulator was chosen specifically because it does not...

Tree stands, not guns, are the midwestern hunter's most dangerous weapon.

PubMed

Crockett, Andrew; Stawicki, Stanislaw P; Thomas, Yalaunda M; Jarvis, Amy M; Wang, Cecily F; Beery, Paul R; Whitmill, Melissa L; Lindsey, David E; Steinberg, Steven M; Cook, Charles H

2010-09-01

Although the prevailing stereotype is that most hunting injuries are gunshot wounds inflicted by intoxicated hunting buddies, our experience led us to hypothesize that falls comprise a significant proportion of hunting related injuries. Trauma databases of two Level I trauma centers in central Ohio were queried for all hunting related injuries during a 10-year period. One hundred and thirty patients were identified (90% male, mean age 41.0 years, range 17-76). Fifty per cent of injuries resulted from falls, whereas gunshot wounds accounted for 29 per cent. Most hunters were hunting deer and 92 per cent of falls were from tree stands. Alcohol was involved in only 2.3 per cent, and drugs of abuse in 4.6 per cent. Of gunshots, 58 per cent were self-inflicted, and 42 per cent were shot by another hunter. Tree stand falls were highly morbid, with 59 per cent of fall victims suffering spinal fractures, 47 per cent lower extremity fractures, 18 per cent upper extremity fractures, and 18 per cent closed head injuries. Surgery was required for 81 per cent of fall-related injuries, and 8.2 per cent of fall victims had permanent neurological deficits. In contrast to prevailing beliefs, in our geographic area tree-stand falls are the most common mechanism of hunting related injury requiring admission to a Level 1 trauma center.

How Do River Meanders Change with Sea Level Rise and Fall?

NASA Astrophysics Data System (ADS)

Scamardo, J. E.; Kim, W.

2016-12-01

River meander patterns are controlled by numerous factors, including variations in water discharge, sediment input, and base level. However, the effect of sea level rise and fall on meandering rivers has not been thoroughly quantified. This study examines geomorphic changes to meandering rivers as a result of sea level rise and fall. Twenty experimental runs using coarse-grained walnut shell sediment (D50= 500 microns) in a flume tank (2.4m x 0.6m x 0.1m) tested the optimal initial conditions for creating meandering rivers in a laboratory setting as well as variations in base level rise and fall rates. Geomorphic changes were recorded by camera images every 20 seconds for a duration of 4 hours per experiment. Seventeen experiments tested the effects of changes in initial base levels, water discharge between 200 and 400 mL/min, and sediment to water input ratios between 1:1000 and 1:250 while measuring sinuosity, channel geometry, and the timescale of the channel to reach a stable form. Sinuosity and channel activity increased with increasing water discharge, initial base level, and the sediment to water ratio to a point after which the activity decreased with increasing sediment input. Base-level change experiments used initial conditions of 400 mL/min, a 1:750 sediment to water input ratio, and a 6 cm initial base-level to induce river meanders for the initial 2 hours before base-level change occurred. Three separate experiments investigated the effects of increasing rates of sea level change: 0.07 cm/min, 0.1 cm/min, and 0.2 cm/min. Experimental sea level was decreased constantly from a high-stand of 6 cm to a low-stand of 2 cm back to the high-stand base-level in each experiment. The rates of change in the experiments scale roughly from central to glacial cycles. In all three experiments, sea level fall induced meander cut-off while sea level rise prompted greater rates of meander bend erosion and meander growth. Sinuosity increased by 12%, 13.5%, and 24%, respectively in the three experiments, with most sinuosity changes occurring in the downstream reach of the channel. These experiments could provide insight into long term effects of sea level change on modern meandering fluvial systems as well as provide a key to interpreting past fluvial changes in the stratigraphic record.

Thinning and Pruning Influence Glaze Damage in a Loblolly Pine Plantation

Treesearch

James D. Burton

1981-01-01

An old-field plantation was thinned and pruned at age 11 and again at age 14 to 4 basal area levels and 3 crown percent levels. A survey was made to determine how damage by an ice storm at age 15 was influenced by treatment. Severe damage was heaviest in the densest stands and in stands with the shortest crowns, while the percent of stand destroyed was least under the...

Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests.

PubMed

Nelson, Kellen N; Turner, Monica G; Romme, William H; Tinker, Daniel B

2016-12-01

Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m 3 (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires. © 2016 by the Ecological Society of America.

5 CFR 351.506 - Effective date of retention standing.

Code of Federal Regulations, 2010 CFR

2010-01-01

... from a competitive level in the order prescribed in § 351.601 is determined as of the date the employee is so released. (b) The retention standing of each employee retained in a competitive level as an...

5 CFR 351.506 - Effective date of retention standing.

Code of Federal Regulations, 2011 CFR

2011-01-01

... from a competitive level in the order prescribed in § 351.601 is determined as of the date the employee is so released. (b) The retention standing of each employee retained in a competitive level as an...

Quasi free-standing epitaxial graphene fabrication on 3C-SiC/Si(111)

NASA Astrophysics Data System (ADS)

Amjadipour, Mojtaba; Tadich, Anton; Boeckl, John J.; Lipton-Duffin, Josh; MacLeod, Jennifer; Iacopi, Francesca; Motta, Nunzio

2018-04-01

Growing graphene on SiC thin films on Si is a cheaper alternative to the growth on bulk SiC, and for this reason it has been recently intensively investigated. Here we study the effect of hydrogen intercalation on epitaxial graphene obtained by high temperature annealing on 3C-SiC/Si(111) in ultra-high vacuum. By using a combination of core-level photoelectron spectroscopy, low energy electron diffraction, and near-edge x-ray absorption fine structure (NEXAFS) we find that hydrogen saturates the Si atoms at the topmost layer of the substrate, leading to free-standing graphene on 3C-SiC/Si(111). The intercalated hydrogen fully desorbs after heating the sample at 850 °C and the buffer layer appears again, similar to what has been reported for bulk SiC. However, the NEXAFS analysis sheds new light on the effect of hydrogen intercalation, showing an improvement of graphene’s flatness after annealing in atomic H at 600 °C. These results provide new insight into free-standing graphene fabrication on SiC/Si thin films.

Relationship between lower extremity isometric muscle strength and standing balance in patients with multiple sclerosis.

PubMed

Citaker, Seyit; Guclu-Gunduz, Arzu; Yazici, Gokhan; Bayraktar, Deniz; Nazliel, Bijen; Irkec, Ceyla

2013-01-01

Muscle strength and standing balance decrease in patients with Multiple Sclerosis (MS). The aim of the present study was to investigate the relationship between the lower extremity isometric muscle strength and standing balance in patients with MS. Forty-seven patients with MS and 10 healthy volunteers were included. Neurological disability level was assessed using Expanded Disability Status Scale (EDSS). Isometric strength of seven lower extremity muscles (hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor) was assessed using hand-held dynamometer. Duration of static one-leg standing balance was measured using digital chronometer. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength, and duration of one-leg standing balance were decreased in patients with MS when compared with controls (p < 0.05). All assessed lower extremity isometric muscle strength and EDSS level was related duration of one-leg standing balance in patients with MS. All assessed lower extremity isometric muscle strength (except ankle dorsal flexor) was related with EDSS. Hip flexor-extensor-abductor-adductor, knee flexor-extensor, and ankle dorsal flexor isometric muscle strength decreases in ambulatory MS patients. Lower extremity muscle weakness and neurological disability level are related with imbalance in MS population. Hip and knee region muscles weakness increases the neurological disability level. For the better balance and decrease neurological disability level whole lower extremity muscle strengthening should be included in rehabilitation programs.

Verification of Spent Nuclear Fuel in Sealed Dry Storage Casks via Measurements of Cosmic-Ray Muon Scattering

DOE PAGES

Durham, J. M.; Poulson, D.; Bacon, J.; ...

2018-04-10

Most of the plutonium in the world resides inside spent nuclear reactor fuel rods. This high-level radioactive waste is commonly held in long-term storage within large, heavily shielded casks. Currently, international nuclear safeguards inspectors have no stand-alone method of verifying the amount of reactor fuel stored within a sealed cask. In this paper, we demonstrate experimentally that measurements of the scattering angles of cosmic-ray muons, which pass through a storage cask, can be used to determine if spent fuel assemblies are missing without opening the cask. Finally, this application of technology and methods commonly used in high-energy particle physics providesmore » a potential solution to this long-standing problem in international nuclear safeguards.« less

Verification of Spent Nuclear Fuel in Sealed Dry Storage Casks via Measurements of Cosmic-Ray Muon Scattering

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

Durham, J. M.; Poulson, D.; Bacon, J.

Most of the plutonium in the world resides inside spent nuclear reactor fuel rods. This high-level radioactive waste is commonly held in long-term storage within large, heavily shielded casks. Currently, international nuclear safeguards inspectors have no stand-alone method of verifying the amount of reactor fuel stored within a sealed cask. In this paper, we demonstrate experimentally that measurements of the scattering angles of cosmic-ray muons, which pass through a storage cask, can be used to determine if spent fuel assemblies are missing without opening the cask. Finally, this application of technology and methods commonly used in high-energy particle physics providesmore » a potential solution to this long-standing problem in international nuclear safeguards.« less

Influence of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing.

PubMed

Karimi, Zanyar; Allahyari, Teimour; Azghani, Mahmood Reza; Khalkhali, Hamidreza

2016-03-01

The present study was an attempt to investigate the effect of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing. Ten healthy subjects were recruited to stand for 2 h in three footwear conditions: barefoot, flat-bottomed shoe and unstable shoe. During standing, lower leg discomfort and EMG activity of medial gastrocnemius (MG) and tibialis anterior (TA) muscles were continuously monitored. Changes in lower leg volume over standing time also were measured. Lower leg discomfort rating reduced significantly while subjects standing on unstable shoe compared to the flat-bottomed shoe and barefoot condition. For lower leg volume, less changes also were observed with unstable shoe. The activity level and variation of right MG muscle was greater with unstable shoe compared to the other footwear conditions; however regarding the left MG muscle, significant difference was found between unstable shoe and flat-bottomed shoe only for activity level. Furthermore no significant differences were observed for the activity level and variation of TA muscles (right/left) among all footwear conditions. The findings suggested that prolonged standing with unstable footwear produces changes in lower leg muscles activity and leads to less volume changes. Perceived discomfort also was lower for this type of footwear and this might mean that unstable footwear can be used as ergonomic solution for employees whose work requires prolonged standing. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Effects of thinning on drought vulnerability and climate response in north temperate forest ecosystems

USGS Publications Warehouse

D’Amato, Anthony W.; Bradford, John B.; Fraver, Shawn; Palik, Brian J.

2013-01-01

Reducing tree densities through silvicultural thinning has been widely advocated as a strategy for enhancing resistance and resilience to drought, yet few empirical evaluations of this approach exist. We examined detailed dendrochronological data from a long-term (>50 yrs) replicated thinning experiment to determine if density reductions conferred greater resistance and/or resilience to droughts, assessed by the magnitude of stand-level growth reductions. Our results suggest that thinning generally enhanced drought resistance and resilience; however, this relationship showed a pronounced reversal over time in stands maintained at lower tree densities. Specifically, lower-density stands exhibited greater resistance and resilience at younger ages (49 years), yet exhibited lower resistance and resilience at older ages (76 years), relative to higher-density stands. We attribute this reversal to significantly greater tree sizes attained within the lower-density stands through stand development, which in turn increased tree-level water demand during the later droughts. Results from response-function analyses indicate that thinning altered growth-climate relationships, such that higher-density stands were more sensitive to growing-season precipitation relative to lower-density stands. These results confirm the potential of density management to moderate drought impacts on growth, and they highlight the importance of accounting for stand structure when predicting climate-change impacts to forest systems.

Effects of thinning on drought vulnerability and climate response in north temperate forest ecosystems.

PubMed

D'Amato, Anthony W; Bradford, John B; Fraver, Shawn; Palik, Brian J

2013-12-01

Reducing tree densities through silvicultural thinning has been widely advocated as a strategy for enhancing resistance and resilience to drought, yet few empirical evaluations of this approach exist. We examined detailed dendrochronological data from a long-term (> 50 years) replicated thinning experiment to determine if density reductions conferred greater resistance and/or resilience to droughts, assessed by the magnitude of stand-level growth reductions. Our results suggest that thinning generally enhanced drought resistance and resilience; however, this relationship showed a pronounced reversal over time in stands maintained at lower tree densities. Specifically, lower-density stands exhibited greater resistance and resilience at younger ages (49 years), yet exhibited lower resistance and resilience at older ages (76 years), relative to higher-density stands. We attribute this reversal to significantly greater tree sizes attained within the lower-density stands through stand development, which in turn increased tree-level water demand during the later droughts. Results from response-function analyses indicate that thinning altered growth-climate relationships, such that higher-density stands were more sensitive to growing-season precipitation relative to lower-density stands. These results confirm the potential of density management to moderate drought impacts on growth, and they highlight the importance of accounting for stand structure when predicting climate-change impacts to forests.

Magnetic resonance studies of the Mg acceptor in thick free-standing and thin-film GaN

NASA Astrophysics Data System (ADS)

Zvanut, Mary Ellen

Mg, the only effective p-type dopant for the nitrides, substitutes for Ga and forms an acceptor with a defect level of about 0.16 eV. The magnetic resonance of such a center should be highly anisotropic, yet early work employing both optically detected magnetic resonance (ODMR) and electron paramagnetic resonance (EPR) spectroscopies revealed a defect with a nearly isotropic g-tensor. The results were attributed to crystal fields caused by compensation and/or strain typical of the heteroepitaxially grown films. The theory was supported by observation of the expected highly anisotropic ODMR signature in homoepitaxially grown films in which dislocation-induced non-uniform strain and compensation are reduced. The talk will review EPR measurements of thin films and describe new work which takes advantage of the recently available thick free-standing GaN:Mg substrates grown by hydride vapor phase epitaxy (HVPE) and high nitrogen pressure solution growth (HNPS). Interestingly, the films and HVPE substrates exhibit characteristically different types of EPR signals, and no EPR response could be induced in the HNPS substrates, with or without illumination. In the heteroepitaxial films, a curious angular dependent line-shape is observed in addition to the nearly isotropic g-tensor characteristic of the Mg-related acceptor. On the other hand, the free-standing HVPE crystals reveal a clear signature of a highly anisotropic shallow acceptor center. Comparison with SIMS measurements implies a direct relation to the Mg impurity, and frequency-dependent EPR studies demonstrate the influence of the anisotropic crystal fields. Overall, the measurements of the thick free-standing crystals show that the Mg acceptor is strongly affected by the local environment. The ODMR was performed by Evan Glaser, NRL and the free-standing Mg-doped HVPE crystals were grown by Jacob Leach, Kyma Tech. The work at UAB is supported by NSF Grant No. DMR-1308446.

Initial soil respiration response to biomass harvesting and green-tree retention in aspen-dominated forests of the Great Lakes region

USGS Publications Warehouse

Kurth, Valerie J.; Bradford, John B.; Slesak, Robert A.; D'Amato, Anthony W.

2014-01-01

Contemporary forest management practices are increasingly designed to optimize novel objectives, such as maximizing biomass feedstocks and/or maintaining ecological legacies, but many uncertainties exist regarding how these practices influence forest carbon (C) cycling. We examined the responses of soil respiration (Rs) to biomass harvesting and green-tree retention in an effort to empirically assess their impacts on C cycling. We measured Rs and soil microclimatic variables over four growing seasons following implementation of these management practices using a fully replicated, operational-scale experiment in aspen-dominated forests in northern Minnesota. Treatments included three levels of biomass removal within harvested areas: whole-tree harvest (no slash deliberately retained), 20% slash retained, and stem-only harvest (all slash retained), and two levels of green-tree retention: 0.1 ha aggregate or none. The relative amount of biomass removed had a negligible effect on Rs in harvested areas, but treatment effects were probably obscured by heterogeneous slash configurations and rapid post-harvest regeneration of aspen in all of the treatments. Discrete measurements of Rs and soil temperature within green-tree aggregates were not discernible from surrounding harvested areas or unharvested control stands until the fourth year following harvest, when Rs was higher in unharvested controls than in aggregates and harvested stands. Growing season estimates of Rs showed that unharvested control stands had higher Rs than both harvested stands and aggregates in the first and third years following harvest. Our results suggest that retention of larger forest aggregates may be necessary to maintain ecosystem-level responses similar to those in unharvested stands. Moreover, they highlight the innate complexity of operational-scale research and suggest that the initial impacts of biomass harvest on Rs may be indiscernible from traditional harvest in systems where incidental breakage is high.

Early forest dynamics in stand-replacing fire patches in the northern Sierra Nevada, California, USA

Treesearch

Brandon M. Collins; Gary B. Roller

2013-01-01

There is considerable concern over the occurrence of stand-replacing fire in forest types historically associated with low- to moderate-severity fire. The concern is largely over whether contemporary levels of stand-replacing fire are outside the historical range of variability, and what natural forest recovery is in these forest types following stand-replacing fire....

Red maple development in mixed hardwood stands in West Virginia

Treesearch

Brian Tift

1997-01-01

Recent evidence has shown that red maple (Acer rubrum) may become a more prominent species in eastern mixed hardwood stands. This study will examine the strategies used by red maple to reach dominant and codominant canopy positions on two different stands (one mesic and one drier). Stand level data such as dbh, height, crown class, height class, and...

Accelerating development with fertilization in a young natural Piedmont mixed hardwood pine stand

Treesearch

B. J. Berenguer; M. H. Gocke; J. L. Schuler; E. Treasure; D. J. Robison

2010-01-01

A rising two-year-old even-aged naturally regenerated upland Piedmont mixed hardwood-pine stand was broadcast fertilized with N, N + P, and N + P + K to evaluate stand level responses to fertility treatments. There were significant positive stand responses in self thinning and mean stem size measured two growing seasons after fertilizer applications. Findings suggest...

Response of ground-dwelling spider assemblages to prescribed fire following stand structure manipulation in the southern Cascade Range

Treesearch

Nancy E. Gillette; Richard S. Vetter; Sylvia R. Mori; Carline R. Rudolph; Dessa R. Welty

2008-01-01

We assessed spider (Arachnida: Araneae) responses to prescribed fire following stand s tructure treatments in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) stands in the Cascade Range of California. Stands were logged or left untreated to create three levels of structural diversity. We logged one treatment to minimize old-growth...

The influence of tree stands and a noise barrier on near-roadway air quality

EPA Science Inventory

Prediction of air pollution exposure levels of people living near or commuting on roadways is still very problematic due to the highly localized nature of traffic intensity, fleet composition, and extremely complex air flow patterns in urban areas. Both modelling and field studie...

In situ visualization for large-scale combustion simulations.

PubMed

Yu, Hongfeng; Wang, Chaoli; Grout, Ray W; Chen, Jacqueline H; Ma, Kwan-Liu

2010-01-01

As scientific supercomputing moves toward petascale and exascale levels, in situ visualization stands out as a scalable way for scientists to view the data their simulations generate. This full picture is crucial particularly for capturing and understanding highly intermittent transient phenomena, such as ignition and extinction events in turbulent combustion.

The impact of volunteer rice infestation on rice yield and grain quality

USDA-ARS?s Scientific Manuscript database

Volunteer rice (Oryza sativa L.) is a crop stand which emerges from shattered seeds of the previous crop. When present at sufficiently high levels, it can potentially affect the commercial market value of cultivated rice products, especially if it produces kernels with quality, uniformity, or size ...

A multivariate mixed model system for wood specific gravity and moisture content of planted loblolly pine stands in the southern United States

Treesearch

Finto Antony; Laurence R. Schimleck; Alex Clark; Richard F. Daniels

2012-01-01

Specific gravity (SG) and moisture content (MC) both have a strong influence on the quantity and quality of wood fiber. We proposed a multivariate mixed model system to model the two properties simultaneously. Disk SG and MC at different height levels were measured from 3 trees in 135 stands across the natural range of loblolly pine and the stand level values were used...

Using landscape-level forest monitoring data to draw a representative picture of an iconic subalpine tree species

Treesearch

Sara A. Goeking; Deborah K. Izlar

2015-01-01

Whitebark pine (Pinus albicaulis) is an ecologically important species in high-altitude, mid-latitude areas of western North America due to the habitat and food source it provides for many wildlife species. Recent concerns about the long-term viability of whitebark pine stands have arisen in the face of high mortality due to a combination of fire...

Litter Decomposition in Low and High Mortality Northern Red Oak Stands on Extremely Acidic Southwestern Pennsylvania Soils

Treesearch

Michael C. Demchik; William E. Sharpe

2004-01-01

Previous research has shown that decomposition of organic matter is slower in soils with high levels of soil acidity and available aluminum (Al). The objective of this experiment was to determine if differences in decomposition rates of northern red oak leaves occurred between extremely acidic and less acidic sites that also differed in oak mortality. Leaf litter from...

[Post-logging organic matter recovery in forest ecosystems of eastern Baikal region].

PubMed

Vedrova, E F; Mukhortova, L V; Ivanov, V V; Krivobokov, L V; Boloneva, M V

2010-01-01

The dynamics of organic matter accumulated in the soil and main vegetation elements was analyzed for post-logging forest ecosystem succession series in eastern Baikal region. The phytomass was found to allocate up 63 and 50% of carbon in undisturbed Scots pine and fir stands, respectively. The post-logging phytomass contribution to the total carbon pool appeared to decrease down to 16% in Scots pine and 6% in fir stands. In Scots pine stands, carbon storage was determined to account for almost 70% of the initial carbon 60 years after logging. In 50- to 55-year-old fir stands, carbon recovered its initial pool only by 10%. Soil carbon recorded in recently logged Scots pine and fir sites appeared to be 5 and 16 times that accumulated in the phytomass, respectively. The ratio between phytomass carbon and soil organic matter recovered back to the prelogging level in Scots pine stands by the age of 50-60 years. While phytomass carbon also increased in fir stand of the same age, it did not reach the level of the control stand.

Standing wave contributions to the linear interference effect in stratosphere-troposphere coupling

NASA Astrophysics Data System (ADS)

Watt-Meyer, Oliver; Kushner, Paul

2014-05-01

A body of literature by Hayashi and others [Hayashi 1973, 1977, 1979; Pratt, 1976] developed a decomposition of the wavenumber-frequency spectrum into standing and travelling waves. These techniques directly decompose the power spectrum—that is, the amplitudes squared—into standing and travelling parts. This, incorrectly, does not allow for a term representing the covariance between these waves. We propose a simple decomposition based on the 2D Fourier transform which allows one to directly compute the variance of the standing and travelling waves, as well as the covariance between them. Applying this decomposition to geopotential height anomalies in the Northern Hemisphere winter, we show the dominance of standing waves for planetary wavenumbers 1 through 3, especially in the stratosphere, and that wave-1 anomalies have a significant westward travelling component in the high-latitude (60N to 80N) troposphere. Variations in the relative zonal phasing between a wave anomaly and the background climatological wave pattern—the "linear interference" effect—are known to explain a large part of the planetary wave driving of the polar stratosphere in both hemispheres. While the linear interference effect is robust across observations, models of varying degrees of complexity, and in response to various types of perturbations, it is not well understood dynamically. We use the above-described decomposition into standing and travelling waves to investigate the drivers of linear interference. We find that the linear part of the wave activity flux is primarily driven by the standing waves, at all vertical levels. This can be understood by noting that the longitudinal positions of the antinodes of the standing waves are typically close to being aligned with the maximum and minimum of the background climatology. We discuss implications for predictability of wave activity flux, and hence polar vortex strength variability.

High-voltage terminal test of a test stand for a 1-MV electrostatic accelerator

NASA Astrophysics Data System (ADS)

Park, Sae-Hoon; Kim, Yu-Seok

2015-10-01

The Korea Multipurpose Accelerator Complex has been developing a 300-kV test stand for a 1-MV electrostatic accelerator ion source. The ion source and accelerating tube will be installed in a high-pressure vessel. The ion source in the high-pressure vessel is required to have a high reliability. The test stand has been proposed and developed to confirm the stable operating conditions of the ion source. The ion source will be tested at the test stand to verify the long-time operating conditions. The test stand comprises a 300-kV high-voltage terminal, a battery for the ion-source power, a 60-Hz inverter, 200-MHz radio-frequency power supply, a 5-kV extraction power supply, a 300-kV accelerating tube, and a vacuum system. The results of the 300-kV high-voltage terminal tests are presented in this paper.

Stand-replacing wildfires increase nitrification for decades in southwestern ponderosa pine forests.

PubMed

Kurth, Valerie J; Hart, Stephen C; Ross, Christopher S; Kaye, Jason P; Fulé, Peter Z

2014-05-01

Stand-replacing wildfires are a novel disturbance within ponderosa pine (Pinus ponderosa) forests of the southwestern United States, and they can convert forests to grasslands or shrublands for decades. While most research shows that soil inorganic N pools and fluxes return to pre-fire levels within a few years, we wondered if vegetation conversion (ponderosa pine to bunchgrass) following stand-replacing fires might be accompanied by a long-term shift in N cycling processes. Using a 34-year stand-replacing wildfire chronosequence with paired, adjacent unburned patches, we examined the long-term dynamics of net and gross nitrogen (N) transformations. We hypothesized that N availability in burned patches would become more similar to those in unburned patches over time after fire as these areas become re-vegetated. Burned patches had higher net and gross nitrification rates than unburned patches (P < 0.01 for both), and nitrification accounted for a greater proportion of N mineralization in burned patches for both net (P < 0.01) and gross (P < 0.04) N transformation measurements. However, trends with time-after-fire were not observed for any other variables. Our findings contrast with previous work, which suggested that high nitrification rates are a short-term response to disturbance. Furthermore, high nitrification rates at our site were not simply correlated with the presence of herbaceous vegetation. Instead, we suggest that stand-replacing wildfire triggers a shift in N cycling that is maintained for at least three decades by various factors, including a shift from a woody to an herbaceous ecosystem and the presence of fire-deposited charcoal.

Forest Stands Selected by Foraging Red-Cockaded Woodpeckers

Treesearch

Robert G. Hooper; Richard F. Harlow

1986-01-01

Selection of forest stands by 18 clans of foraging red-cockaded woodpeckers was studied in their year-round home ranges. The foraging use of 276 stands relative to their availability within the home ranges was compared to several stand characteristics. Selection among stands with similar characteristics was highly vairable and red-cockadeds foraged in stands with a...

Custom Gradient Compression Stockings May Prevent Orthostatic Intolerance in Astronauts After Space Flight

NASA Technical Reports Server (NTRS)

Stenger, Michael B.; Lee, Stuart M. C.; Westby, Christian M.; Platts, Steven H.

2010-01-01

Orthostatic intolerance after space flight is still an issue for astronauts as no in-flight countermeasure has been 100% effective. NASA astronauts currently wear an inflatable anti-gravity suit (AGS) during re-entry, but this device is uncomfortable and loses effectiveness upon egress from the Shuttle. We recently determined that thigh-high, gradient compression stockings were comfortable and effective after space flight, though to a lesser degree than the AGS. We also recently showed that addition of splanchnic compression to this thigh-high compression stocking paradigm improved orthostatic tolerance to a level similar to the AGS, in a ground based model. Purpose: The purpose of this study was to evaluate a new, three-piece breast-high gradient compression garment as a countermeasure to post-space flight orthostatic intolerance. Methods: Eight U.S. astronauts have volunteered for this experiment and were individually fitted for a three-piece, breast-high compression garment to provide 55 mmHg compression at the ankle which decreased to approximately 20 mmHg at the top of the leg and provides 15 mmHg over the abdomen. Orthostatic testing occurred 30 days pre-flight (w/o garment) and 2 hours after flight (w/ garment) on landing day. Blood pressure (BP), Heart Rate (HR) and Stroke Volume (SV) were acquired for 2 minutes while the subject lay prone and then for 3.5 minutes after the subject stands up. To date, two astronauts have completed pre- and post-space flight testing. Data are mean SD. Results: BP [pre (prone to stand): 137+/-1.6 to 129+/-2.5; post: 130+/-2.4 to 122+/-1.6 mmHg] and SV [pre (prone to stand): 61+/-1.6 to 38+/-0.2; post: 58+/-6.4 to 37+/-6.0 ml] decreased with standing, but no differences were seen post-flight w/ compression garments compared to pre-flight w/o garments. HR [pre (prone to stand): 66+/-1.6 to 74+/-3.0, post: 67+/-5.6 to 78+/-6.8 bpm] increased with standing, but no differences were seen pre- to post-flight. Conclusion: After space flight, blood pressure and stroke volume are normally decreased and heart rate is usually elevated to compensate. In this small group of subjects, breast-high gradient compression stockings seem to have prevented these negative effects of spaceflight.

Nocturnal diastolic blood pressure decline is associated with higher 25-hydroxyvitamin D level and standing plasma renin activity in a hypertensive population.

PubMed

Zhang, Mingchen; Xu, Xinjuan; Liu, Haiming; Li, Haixia; Zhang, Junshi; Gao, Min

2017-01-01

Patients with nondipper hypertension are known to carry a high risk of cardiovascular complications. Vitamin D deficiency is associated with hypertension. Because vitamin D deficiency activates the renin-angiotensin-aldosterone system (RAAS), we hypothesized that this vitamin would interact with the RAAS to influence blood pressure (BP) in nondipper hypertensive patients. We performed a cross-sectional analysis of 1,007 outpatients with hypertension (HTN). Dipper and nondipper patterns were detected, and the two groups were matched for clinical, laboratory, 25-hydroxyvitamin D (25OHD) levels, and ambulatory blood pressure recording. Plasma renin activity (PRA), angiotensin II, and plasma aldosterone concentration (PAC) were assessed in 174 patients treated with calcium channel blockers or no medication. The mean 25OHD concentration in the entire study population was 12.3ng/dL, and the prevalence of vitamin D deficiency was 87.0%. Dipper and nondipper HTN were noted in 187 patients (24.6%) and 573 patients (75.4%). 25OHD levels were similar between nondipper and dipper HTN groups. Forward stepwise logistic regression analysis showed that BMI and age were independent predictors of nondipper HTN. Neither 25OHD levels nor RAAS components were included in the model. In correlation analyses, nocturnal decline of diastolic BP was positively associated with 25OHD levels and standing PRA (r = 0.152 p = 0.045, r = 0.165 p = 0.038, respectively). The present study showed that vitamin D deficiency was astonishingly prevalent in hypertensive subjects residing in Xinjiang, China. There may be a weakly association of nocturnal DBP decline with 25OHD levels and standing PRA levels. We found no association between vitamin D deficiency and nondipper HTN.

Disturbance affects short-term facilitation, but not long-term saturation, of exotic plant invasion in New Zealand forest

PubMed Central

Spence, Laura A.; Ross, Joshua V.; Wiser, Susan K.; Allen, Robert B.; Coomes, David A.

2011-01-01

We investigate the spread of an exotic herb, Hieracium lepidulum, into a New Zealand Nothofagus forest with the aim of understanding how stand-development of tree populations, propagule pressure and invader persistence, affect invasion across the landscape and within communities. Using data repeatedly collected over 35 years, from 250 locations, we parametrize continuous-time Markov chain models and use these models to examine future projections of the invasion under a range of hypothetical scenarios. We found that the probability of invasion into a stand was relatively high following canopy disturbance and that local abundance of Hieracium was promoted by minor disturbances. However, model predictions extrapolated 45 years into the future show that neither the rate of landscape-level invasion, nor local population growth of Hieracium, was affected much by changing the frequency of canopy disturbance events. Instead, invasion levels were strongly affected by the ability of Hieracium to persist in the understorey following forest canopy closure, and by propagule supply from streams, forest edges and plants already established within the stand. Our results show that disturbance frequency has surprisingly little influence on the long-term trajectory of invasion, while invader persistence strongly determines invasion patterns. PMID:20980298

Effects of Dwarf Mistletoe on Stand Structure of Lodgepole Pine Forests 21-28 Years Post-Mountain Pine Beetle Epidemic in Central Oregon

PubMed Central

Agne, Michelle C.; Shaw, David C.; Woolley, Travis J.; Queijeiro-Bolaños, Mónica E.

2014-01-01

Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum) also influences stand structure and occurs frequently in post-mountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although they co-occur frequently on the landscape. The aim of this study is to investigate the stand structure of lodgepole pine forests 21–28 years after a mountain pine beetle epidemic with varying levels of dwarf mistletoe infection in the Deschutes National Forest in central Oregon. We compared stand density, stand basal area, canopy volume, proportion of the stand in dominant/codominant, intermediate, and suppressed cohorts, average height and average diameter of each cohort, across the range of dwarf mistletoe ratings to address differences in stand structure. We found strong evidence of a decrease in canopy volume, suppressed cohort height, and dominant/codominant cohort diameter with increasing stand-level dwarf mistletoe rating. There was strong evidence that as dwarf mistletoe rating increases, proportion of the stand in the dominant/codominant cohort decreases while proportion of the stand in the suppressed cohort increases. Structural differences associated with variable dwarf mistletoe severity create heterogeneity in this forest type and may have a significant influence on stand productivity and the resistance and resilience of these stands to future biotic and abiotic disturbances. Our findings show that it is imperative to incorporate dwarf mistletoe when studying stand productivity and ecosystem recovery processes in lodgepole pine forests because of its potential to influence stand structure. PMID:25221963

Enhanced oxidative stress in workers with a standing occupation

PubMed Central

Flore, R; Gerardino, L; Santoliquido, A; Pola, R; Flex, A; Di, C; Pola, P; Tondi, P

2004-01-01

Aims and Methods: To evaluate venous pressure of the lower limbs and reactive oxygen species (ROS) before and after work in 62 workers with a standing occupation (surgery room nurses) and 65 outpatient department nurses who can walk during their working time. Results: After work, a statistically significant increase of venous pressure of the lower limbs levels was observed in both the study group and controls. Standing workers showed significantly higher mean levels of ROS after work. PMID:15150396

Extent of Pleistocene lakes in the western Great Basin

USGS Publications Warehouse

Reheis, Marith C.

1999-01-01

During the Pliocene to middle Pleistocene, pluvial lakes in the western Great Basin repeatedly rose to levels much higher than those of the well-documented late Pleistocene pluvial lakes, and some presently isolated basins were connected. Sedimentologic, geomorphic, and chronologic evidence at sites shown on the map indicates that Lakes Lahontan and Columbus-Rennie were as much as 70 m higher in the early-middle Pleistocene than during their late Pleistocene high stands. Lake Lahontan at its 1400-m shoreline level would submerge present-day Reno, Carson City, and Battle Mountain, and would flood other now-dry basins. To the east, Lakes Jonathan (new name), Diamond, Newark, and Hubbs also reached high stands during the early-middle(?) Pleistocene that were 25-40 m above their late Pleistocene shorelines; at these very high levels, the lakes became temporarily or permanently tributary to the Humboldt River and hence to Lake Lahontan. Such a temporary connection could have permitted fish to migrate from the Humboldt River southward into the presently isolated Newark Valley and from Lake Lahontan into Fairview Valley. The timing of drainage integration also provides suggested maximum ages for fish to populate the basins of Lake Diamond and Lake Jonathan. Reconstructing and dating these lake levels also has important implications for paleoclimate, tectonics, and drainage evolution in the western Great Basin. For example, shorelines in several basins form a stair-step sequence downward with time from the highest levels, thought to have formed at about 650 ka, to the lowest, formed during the late Pleistocene. This descending sequence indicates progressive drying of pluvial periods, possibly caused by uplift of the Sierra Nevada and other western ranges relative to the western Great Basin. However, these effects cannot account for the extremely high lake levels during the early middle Pleistocene; rather, these high levels were probably due to a combination of increased effective moisture and changes in the size of the Lahontan drainage basin.

Skyline logging productivity under alternative harvesting prescriptions and levels of utilization in larch-fir stands

Treesearch

Rulon B. Gardner

1980-01-01

Larch-fir stands in northwest Montana were experimentally logged to determine the influence of increasingly intensive levels of utilization upon rates of yarding production, under three different silvicultural prescriptions. Variables influencing rate of production were also identified.

Spine and Spinal Cord Injuries After Falls From Tree Stands During the Wisconsin Deer Hunting Season.

PubMed

Hamilton, Kimberly; Rocque, Brandon; Brooks, Nathaniel

2017-11-01

Deer hunting is popular in much of the United States. In Wisconsin, use of tree stands for hunting is common. Spine surgeons at a Level 1 Trauma Center observed a high incidence of spine and spinal cord injury due to falls from tree stands while hunting. This study's purpose is to systematically characterize and classify those injuries. We reviewed the University of Wisconsin Hospital and Clinics' trauma database for tree stand-related injuries from 1999 to 2013. We collected and analyzed data pertaining to hunters' demographics, comorbidities, type and mechanism of injury, injury severity, and management. We identified 117 patients evaluated after a tree stand fall. Sixty-five (ages 16-76) suffered spine fractures that occurred at all levels, from occipital condyle to sacrum, with thoracolumbar compression and burst fractures being most common. Fractures occurred in the following locations: cranio-cervical junction (8.7%), cervical spine (7.6%), cervical-thoracic junction (6.5%), thoracic spine (32.6%), thoracolumbar junction (33.7%), and lumbar spine (10.9%). Twenty-one patients (32%) experienced a single spinal fracture; 44 patients (68%) suffered multiple spinal fractures. Twenty-five patients (38%) required surgical fixation; 19 patients experienced loss of neurologic function: 5 complete spinal cord injuries (SCI), 5 incomplete SCI, 2 central cord syndromes, and 8 radiculopathies. Two mortalities, both of cardiopulmonary etiology, were noted-one in a patient without a spine fracture and the other in a patient with a complete spinal cord injury at T4. The majority of spine fractures are treated nonoperatively. However, enough patients require surgical intervention that consultation with a neurosurgical or orthopedic spine surgeon is prudent. It is more common to have multiple spine fractures from a tree stand fall, therefore, it is recommended that if 1 fracture is identified the entire spine be evaluated for additional fractures. For safety, it is recommended that hunters wear and use safety harnesses appropriately. Additionally, keeping the height of the tree stand at 10 feet or less is associated with a lower likelihood of spinal cord injury. Further study is needed to determine additional interventions such as education that might reduce the injury frequency in this population.

Changes in leaf area, nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient.

PubMed

Oikawa, Shimpei; Ainsworth, Elizabeth A

2016-08-01

Influences of ozone (O3) on light-saturated rates of photosynthesis in crop leaves have been well documented. To increase our understanding of O3 effects on individual- or stand level productivity, a mechanistic understanding of factors determining canopy photosynthesis is necessary. We used a canopy model to scale photosynthesis from leaf to canopy, and analyzed the importance of canopy structural and leaf ecophysiological characteristics in determining canopy photosynthesis in soybean stands exposed to 9 concentrations of [O3] (37-116 ppb; 9-h mean). Light intensity and N content peaked in upper canopy layers, and sharply decreased through the lower canopy. Plant leaf area decreased with increasing [O3] allowing for greater light intensity to reach lower canopy levels. At the leaf level, light-saturated photosynthesis decreased and dark respiration increased with increasing [O3]. These data were used to calculate daily net canopy photosynthesis (Pc). Pc decreased with increasing [O3] with an average decrease of 10% for an increase in [O3] of 10 ppb, and which was similar to changes in above-ground dry mass production of the stands. Absolute daily net photosynthesis of lower layers was very low and thus the decrease in photosynthesis in the lower canopy caused by elevated [O3] had only minor significance for total canopy photosynthesis. Sensitivity analyses revealed that the decrease in Pc was associated with changes in leaf ecophysiology but not with decrease in leaf area. The soybean stands were very crowded, the leaves were highly mutually shaded, and sufficient light for positive carbon balance did not penetrate to lower canopy leaves, even under elevated [O3]. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pulling Rank: Military Rank Affects Hormone Levels and Fairness in an Allocation Experiment.

PubMed

Siart, Benjamin; Pflüger, Lena S; Wallner, Bernard

2016-01-01

Status within social hierarchies has great effects on the lives of socially organized mammals. Its effects on human behavior and related physiology, however, is relatively little studied. The present study investigated the impact of military rank on fairness and behavior in relation to salivary cortisol (C) and testosterone (T) levels in male soldiers. For this purpose 180 members of the Austrian Armed Forces belonging to two distinct rank groups participated in two variations of a computer-based guard duty allocation experiment. The rank groups were (1) warrant officers (high rank, HR) and (2) enlisted men (low rank, LR). One soldier from each rank group participated in every experiment. At the beginning of the experiment, one participant was assigned to start standing guard and the other participant at rest. The participant who started at rest could choose if and when to relieve his fellow soldier and therefore had control over the experiment. In order to trigger perception of unfair behavior, an additional experiment was conducted which was manipulated by the experimenter. In the manipulated version both soldiers started in the standing guard position and were never relieved, believing that their opponent was at rest , not relieving them. Our aim was to test whether unfair behavior causes a physiological reaction. Saliva samples for hormone analysis were collected at regular intervals throughout the experiment. We found that in the un-manipulated setup high-ranking soldiers spent less time standing guard than lower ranking individuals. Rank was a significant predictor for C but not for T levels during the experiment. C levels in the HR group were higher than in the LR group. C levels were also elevated in the manipulated experiment compared to the un-manipulated experiment, especially in LR. We assume that the elevated C levels in HR were caused by HR feeling their status challenged by the situation of having to negotiate with an individual of lower military rank. This would be in line with the observation that unequally shared duty favored HR in most cases. We conclude that social status, in the form of military rank affects fairness behavior in social interaction and endocrine levels.

Pulling Rank: Military Rank Affects Hormone Levels and Fairness in an Allocation Experiment

PubMed Central

Siart, Benjamin; Pflüger, Lena S.; Wallner, Bernard

2016-01-01

Status within social hierarchies has great effects on the lives of socially organized mammals. Its effects on human behavior and related physiology, however, is relatively little studied. The present study investigated the impact of military rank on fairness and behavior in relation to salivary cortisol (C) and testosterone (T) levels in male soldiers. For this purpose 180 members of the Austrian Armed Forces belonging to two distinct rank groups participated in two variations of a computer-based guard duty allocation experiment. The rank groups were (1) warrant officers (high rank, HR) and (2) enlisted men (low rank, LR). One soldier from each rank group participated in every experiment. At the beginning of the experiment, one participant was assigned to start standing guard and the other participant at rest. The participant who started at rest could choose if and when to relieve his fellow soldier and therefore had control over the experiment. In order to trigger perception of unfair behavior, an additional experiment was conducted which was manipulated by the experimenter. In the manipulated version both soldiers started in the standing guard position and were never relieved, believing that their opponent was at rest, not relieving them. Our aim was to test whether unfair behavior causes a physiological reaction. Saliva samples for hormone analysis were collected at regular intervals throughout the experiment. We found that in the un-manipulated setup high-ranking soldiers spent less time standing guard than lower ranking individuals. Rank was a significant predictor for C but not for T levels during the experiment. C levels in the HR group were higher than in the LR group. C levels were also elevated in the manipulated experiment compared to the un-manipulated experiment, especially in LR. We assume that the elevated C levels in HR were caused by HR feeling their status challenged by the situation of having to negotiate with an individual of lower military rank. This would be in line with the observation that unequally shared duty favored HR in most cases. We conclude that social status, in the form of military rank affects fairness behavior in social interaction and endocrine levels. PMID:27891109

Mixed-effects models for estimating stand volume by means of small footprint airborne laser scanner data.

Treesearch

J. Breidenbach; E. Kublin; R. McGaughey; H.-E. Andersen; S. Reutebuch

2008-01-01

For this study, hierarchical data sets--in that several sample plots are located within a stand--were analyzed for study sites in the USA and Germany. The German data had an additional hierarchy as the stands are located within four distinct public forests. Fixed-effects models and mixed-effects models with a random intercept on the stand level were fit to each data...

Respiration from the organ level to the stand

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

Sprugel, D.G.; Ryan, M.G.; Brooks, J.R.

1995-07-01

The status of efforts to estimate respiration of conifers varies sharply from one tissue to another. There have been numerous measurements of foliage respiration in conifers, but relatively few measurements of within-stand variation in reference to parameters that might be used for scaling. However, a number of logical models for scaling have been proposed (e.g., light, age, or N) and general directions for future research seem well established. There are far fewer measurements of woody-tissue respiration that might be useful for scaling, but some consensus seems to have developed that the use of sapwood biomass and growth rates as indicesmore » may provide the key to scaling woody-tissue respiration up to the stand level. Root respiration is still bogged down by a plurality of methods, each of which seems to have some serious disadvantages, so that even the nature of within-stand variation is poorly known. Successful and believable scaling of root respiration from tissue-specific measurements to the stand level seems to be far in the future. Finally, proxy measurements such as litterfall and N concentration can and have been used to estimate respiration for whole stands without measuring tissue-specific rates at all, but all of these techniques require assumptions that need further testing before they will be generally accepted.« less

An analytical model of stand dynamics as a function of tree growth, mortality and recruitment: the shade tolerance-stand structure hypothesis revisited.

PubMed

Zavala, Miguel A; Angulo, Oscar; Bravo de la Parra, Rafael; López-Marcos, Juan C

2007-02-07

Light competition and interspecific differences in shade tolerance are considered key determinants of forest stand structure and dynamics. Specifically two main stand diameter distribution types as a function of shade tolerance have been proposed based on empirical observations. All-aged stands of shade tolerant species tend to have steeply descending, monotonic diameter distributions (inverse J-shaped curves). Shade intolerant species in contrast typically exhibit normal (unimodal) tree diameter distributions due to high mortality rates of smaller suppressed trees. In this study we explore the generality of this hypothesis which implies a causal relationship between light competition or shade tolerance and stand structure. For this purpose we formulate a partial differential equation system of stand dynamics as a function of individual tree growth, recruitment and mortality which allows us to explore possible individual-based mechanisms--e.g. light competition-underlying observed patterns of stand structure--e.g. unimodal or inverse J-shaped equilibrium diameter curves. We find that contrary to expectations interspecific differences in growth patterns can result alone in any of the two diameter distributions types observed in the field. In particular, slow growing species can present unimodal equilibrium curves even in the absence of light competition. Moreover, light competition and shade intolerance evaluated both at the tree growth and mortality stages did not have a significant impact on stand structure that tended to converge systematically towards an inverse J-shaped curves for most tree growth scenarios. Realistic transient stand dynamics for even aged stands of shade intolerant species (unimodal curves) were only obtained when recruitment was completely suppressed, providing further evidence on the critical role played by juvenile stages of tree development (e.g. the sampling stage) on final forest structure and composition. The results also point out the relevance of partial differential equations systems as a tool for exploring the individual-level mechanisms underpinning forest structure, particularly in relation to more complex forest simulation models that are more difficult to analyze and to interpret from a biological point of view.

N2-fixation dynamics during ecosystem recovery in longleaf pine savannas

NASA Astrophysics Data System (ADS)

Tierney, J. A.

2016-12-01

Biological nitrogen fixation (BNF) can alleviate nitrogen (N) deficiencies that inhibit ecosystem recovery. BNF may be particularly important in ecosystems recovering from land-use change and perturbations from fire, as these disturbances can exacerbate N limitation. Here, we investigated how BNF dynamics change throughout ecosystem development in restored longleaf pine savannas, and how BNF responds to fire. We conducted this study in 59 1-ha plots of longleaf pine distributed across gradients of stand age and fire frequency at two sites in the southeastern US. We determined BNF contributions by three functional groups of N2-fixers (herbaceous legumes, biological soil crusts, and asymbiotic N2-fixing bacteria) by quantifying their abundances, assessing nitrogenase activity, and scaling these estimates up to the plot-level. To determine aboveground N demands, we measured tree growth using diameter increments and allometric equations paired with tissue-specific N concentrations. We fit linear models to evaluate the effects of stand age and time since fire on BNF and N demands throughout stand development, and performed separate analyses on mature stands to determine how fire return interval affects BNF. We observed distinct temporal patterns of N2-fixation across stand development among the three groups of N2 fixers. N2-fixation by legumes and asymbiotic bacteria remained low until stands reached maturity, while N2-fixation by biological soil crusts (BSCs) was high in juvenile stands and decreased with stand age. These patterns suggest a compensatory shift in the importance of these functional groups throughout stand development such that contributions from BSCs are critical for meeting N demands when disturbances may hinder the establishment of legumes and asymbiotic bacteria. N2-fixation by BSCs and asymbiotic bacteria throughout stand development was not affected by time since fire, but legume abundance increased the year following fire, suggesting a recovery mechanism provided by this group. Our findings suggest that BSCs are the most important source of new N in the early phases of ecosystem restoration. In contrast, legumes appear to be critical in mature longleaf pine stands that burn frequently, and particularly for supplying new N in the year following a fire event.

A combination of clinical balance measures and FRAX® to improve identification of high-risk fallers.

PubMed

Najafi, David A; Dahlberg, Leif E; Hansson, Eva Ekvall

2016-05-03

The FRAX® algorithm quantifies a patient's 10-year probability of a hip or major osteoporotic fracture without taking an individual's balance into account. Balance measures assess the functional ability of an individual and the FRAX® algorithm is a model that integrates the individual patients clinical risk factors [not balance] and bone mineral density. Thus, clinical balance measures capture aspects that the FRAX® algorithm does not, and vice versa. It is therefore possible that combining FRAX® and clinical balance measures can improve the identification of patients at high fall risk and thereby high fracture risk. Our study aim was to explore whether there is an association between clinical balance measures and fracture prediction obtained from FRAX®. A cross-sectional study design was used where post hoc was performed on a dataset of 82 participants (54 to 89 years of age, mean age 71.4, 77 female), with a fall-related wrist-fracture between 2008 and 2012. Balance was measured by tandem stance, standing one leg, walking in the figure of eight, walking heel to toe on a line, walking as fast as possible for 30 m and five times sit to stand balance measures [tandem stance and standing one leg measured first with open and then with closed eyes] and each one analyzed for bivariate relations with the 10-year probability values for hip and major osteoporotic fractures as calculated by FRAX® using Spearman's rank correlation test. Individuals with high FRAX® values had poor outcome in balance measures; however the significance level of the correlation differed between tests. Standing one leg eyes closed had strongest correlation to FRAX® (0.610 p = < 0.01) and Five times sit to stand was the only test that did not correlate with FRAX® (0.013). This study showed that there is an association between clinical balance measures and FRAX®. Hence, the use of clinical balance measures and FRAX® in combination, might improve the identification of individuals with high risk of falls and thereby following fractures. Results enable healthcare providers to optimize treatment and prevention of fall-related fractures. The study has been registered in Clinical Trials.gov, registration number NCT00988572 .

Chapter 9: Marking and assessing forest heterogeneity

Treesearch

M. North; J. Sherlock

2012-01-01

Marking guidelines commonly use stocking level, crown class, and species preferences to meet management objectives. Traditionally, these guidelines were applied across the extent of the stand. Current marking guidelines are more flexible, responding to within-stand variability with different stocking level, crown class, and species preference guidelines in...

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

Bonachea, Dan; Hargrove, P.

GASNet is a language-independent, low-level networking layer that provides network-independent, high-performance communication primitives tailored for implementing parallel global address space SPMD languages and libraries such as UPC, UPC++, Co-Array Fortran, Legion, Chapel, and many others. The interface is primarily intended as a compilation target and for use by runtime library writers (as opposed to end users), and the primary goals are high performance, interface portability, and expressiveness. GASNet stands for "Global-Address Space Networking".

Total carbon and nitrogen in mineral soil after 26 years of prescribed fire: Long Valley and Fort Valley Experimental Forests

Treesearch

Daniel G. Neary; Sally M. Haase; Steven T. Overby

2008-01-01

Prescribed fire was introduced to high density ponderosa pine stands at Fort Valley and Long Valley Experimental Forests in 1976. This paper reports on mineral soil total carbon (C) and nitrogen (N) at Long Valley. Total soil C and N levels were highly variable and exhibited an increasing, but inconsistent, concentration trend related to burn interval. Total N ranged...

Factors associated with the decline disease of sugar maple on the Allegheny Plateau

Treesearch

Stephen B. Horsley; Robert P. Long; Scott W. Bailey; Richard A. Hallett; Thomas J. Hall

2000-01-01

Mortality of sugar maple (Acer saccharum Marsh.) has reached unusually high levels across northern Pennsylvania since the early to mid-1980s. We evaluated the influence of glaciation, topographic position, foliage chemistry, defoliation history, and stand characteristics (species composition, structure, density) on the health of sugar maple in 43...

Are U.S Students Ready to Compete?: The Latest on Each State's International Standing

ERIC Educational Resources Information Center

Peterson, Paul E.; Lastra-Anadon, Carlos Xabel; Hanushek, Eric A.; Woessmann, Ludger

2011-01-01

At a time of persistent unemployment, especially among the less skilled, many wonder whether American schools are adequately preparing students for the 21st-century global economy. Despite high unemployment rates, firms are experiencing shortages of educated workers, outsourcing professional-level work to workers abroad, and competing for the…

OPPORTUNITIES IN NITROGEN MANAGEMENT RESEARCH; IMPROVING APPLICATIONS FOR PROVEN TECHNOLOGIES AND IDENTIFYING NEW TOOLS FOR MANAGING NITROGEN FLUX AND INPUT IN ECOSYSTEMS

EPA Science Inventory

The presence and distribution of undesirable quantities of bioavailable nitrogenous compounds in the environment are issues of long-standing concern. Importantly for us today, deleterious effects associated with high levels of nitrogen in the ecosystem are becoming everyday news...

Managing ecosystems for forest health: An approach and the effects on uses and values

Treesearch

Chadwick D. Oliver; Dennis E. Ferguson; Alan E. Harvey; Herbert S. Malany; John M. Mandzak; Robert W. Mutch

1994-01-01

Forest health is most appropriately based on the scientific paradigm of dynamic, constantly changing forest ecosystems. Many forests in the Inland West now support high levels of insect infestations, disease epidemics, fire susceptibilities, and imbalances in stand structures and habitats because of natural processes and past management practices. Impending,...

The Baccalaureate in the California Community College: Current Challenges & Future Prospects

ERIC Educational Resources Information Center

Gándara, Patricia; Cuellar, Marcela

2016-01-01

Concerns over the United States' global standing have spurred a national focus on improving postsecondary attainment. At the same time, many sectors of the economy find they have difficulty recruiting highly trained individuals to fill the good jobs that exist; jobs like nursing, respiratory care, dental hygiene, and various mid-level management…

Implementing a High School Level Geospatial Technologies and Spatial Thinking Course

ERIC Educational Resources Information Center

Nielsen, Curtis P.; Oberle, Alex; Sugumaran, Ramanathan

2011-01-01

Understanding geospatial technologies (GSTs) and spatial thinking is increasingly vital to contemporary life including common activities and hobbies; learning in science, mathematics, and social science; and employment within fields as diverse as engineering, health, business, and planning. As such, there is a need for a stand-alone K-12…

Wood and understory production under a range of ponderosa pine stocking levels, Black Hills, South Dakota

Treesearch

Daniel W. Uresk; Carleton B. Edminster; Kieth E. Severson

2000-01-01

Stemwood and understory production (kg ha-1) were estimated during 3 nonconsecutive years on 5 growing stock levels of ponderosa pine including clearcuts and unthinned stands. Stemwood production was consistently greater at mid- and higher pine stocking levels, and understory production was greater in stands with less pine; however, there were no...

Water potential in ponderosa pine stands of different growing-stock levels

Treesearch

J. M. Schmid; S. A. Mata; R. K. Watkins; M. R. Kaufmann

1991-01-01

Water potential was measured in five ponderosa pine (Pinus ponderosa Laws.) in each of four stands of different growing-stock levels at two locations in the Black Hills of South Dakota. Mean water potentials at dawn and midday varied significantly among growing-stock levels at one location, but differences were not consistent. Mean dawn and midday water potentials...

The effect of knee extensor open kinetic chain resistance training in the ACL-injured knee.

PubMed

Barcellona, Massimo G; Morrissey, Matthew C; Milligan, Peter; Clinton, Melissa; Amis, Andrew A

2015-11-01

To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee. Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12). The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups. Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles. Randomised controlled trial, Level II.

Predicting the Probability of Stand Disturbance

Treesearch

Gregory A. Reams; Joseph M. McCollum

1999-01-01

Forest managers are often interested in identifying and scheduling future stand treatment opportunities. One of the greatest management opportunities is presented following major stand level disturbances that result from natural or anthropogenic forces. Remeasurement data from the Forest Inventory and Analysis (FIA) permanent plot system are used to fit a set of...

Estimating Value Contribution of Tree and Stand Condition

Treesearch

R. Joss Hanna; Richard P. Thompson; Douglas D. Piirto; Jay E. Noel

1997-01-01

Key issues in encouraging forest management at the interface level in the oak woodlands are fire abatement, stand improvement, infection reduction, and hazard tree removal. The development of effective management prescriptions for stand improvement and economic returns provide guidance for homeowners, appraisers, and realtors. The purpose of this research project was...

Patch to landscape patterns in post fire recruitment of a serotinous conifer

USGS Publications Warehouse

Ne'eman, Gidi; Fotheringham, C.J.; Keeley, J.E.

1999-01-01

Obligate seeding species are highly specialized to fire disturbance and many conifers such as cypress, which are adapted to high intensity stand-replacing fires, have canopy seed banks stored in serotinous cones. Resilience of these trees to fire disturbance is a function of disturbance frequency and one focus of this study was to determine the effect of patch age on postfire recruitment. A second focus was to determine the extent to which fire induced a landscape level change in the location of the forest boundary. Prior to a fire in 1994, a large Cupressus sargentii forest was a mosaic landscape of different aged patches of nearly pure cypress bordered by chaparral. Patches less than 60 years of age were relatively dense with roughly one tree every 1-2 m2 but older patches had thinned to one tree every 3-15 m2. Older trees had substantially greater canopy cone crops but the stand level seed bank size was not significantly correlated with stand age. Fire-dependent obligate seeding species are sensitive to fire return interval because of potential changes in the size of seed banks - facing both a potential 'immaturity risk' and a 'senescence risk'. At our site, C. sargentii regeneration was substantial in stands as young as 20 years, suggesting that fire return interval would need to be shorter than this to pose any significant risk. Reduced seedling recruitment in stands nearly 100 years of age may indicate risk from senescence is greater, however, even the lowest density seedling recruitment was many times greater than the density of mature forests - thus this cypress would appear to be resilient to a wide range of fire return intervals. Changes in landscape patterning of forest and chaparral are unlikely except after fire. Factors that inhibit tree establishment within the shrubland, as well as factors that affect shrub establishment within the forest border likely affect the 'permeability' of this ecotone. After the 1994 fire this boundary appeared to be stable in that cypress recruited best within the shadow of burned canopies and cypress were weak invaders of adjacent shrublands.

Stand density, stand structure, and species composition in transition oak stands of northwestern Pennsylvania

Treesearch

S.L. Stout

1991-01-01

Transition stands, those containing species associated with both the northern hardwood and oak-hickory forest types, are important to forest diversity in northwestern Pennsylvania. These stands have high value for a variety of forest uses, including timber production, wildlife habitat, and aesthetics. Diameter distributions are characteristically stratified by species...

Groundwater Availability Alters Soil-plant Nutrient Cycling in a Stand of Invasive, N-fixing Phreatophytes

NASA Astrophysics Data System (ADS)

Dudley, B. D.; Miyazawa, Y.; Hughes, F.; Ostertag, R.; Kettwich, S. K.; MacKenzie, R.; Dulaiova, H.; Waters, C. A.; Bishop, J.; Giambelluca, T. W.

2013-12-01

N-fixing phreatophytic trees are common in arid and semi-arid regions worldwide, and can play significant roles in modifying hydrology and soil-plant nutrient cycling where they are present. In light of reductions in groundwater levels in many arid regions we estimated annual transpiration rates at a stand level, and alterations to C, N and P accretion in soils as a function of groundwater depth in a ca.120 year old stand of Prosopis pallida along an elevation gradient in coastal leeward Hawaii. We measured sapflow and stand level sapwood area to quantify transpiration, and calculated groundwater transpiration rates using P. pallida stem water δ18O values. By measuring soil resistivity, we were able to compare the volume of groundwater transpired by these trees to groundwater depth across the stand. We examined nutrient deposition and accretion in soils in lowland areas of the stand with accessible shallow groundwater, compared to upland areas with no groundwater access, as indicated by stem water δ18O values. Resistivity results suggested that groundwater was at a height close to sea level throughout the stand. Transpiration was around 1900 m3 ha-1 year-1 in the areas of the stand closest to the sea (where groundwater was at around 1-4 m below ground level) and decreased to around a tenth of that volume where groundwater was not accessible. Litterfall rates over the course of the year studied were 17 times greater at lowland sites, but this litterfall contributed ca. 24 times the N, and 35 times the P of upland sites. Thus, groundwater access contributed to the total mass of nitrogen and phosphorus deposited in the form of litter through higher litter quantity and quality. Total N content of soils was 4.7 times greater and inorganic N pools were eight times higher at lowland plots. These results suggest that groundwater depth can have strong effects on soil-plant nutrient cycling, so that reductions in the availability of shallow groundwater are likely to impact soil nutrient availability in arid regions.

Recommended Practices in Thrust Measurements

NASA Technical Reports Server (NTRS)

Polk, James E.; Pancotti, Anthony; Haag, Thomas; King, Scott; Walker, Mitchell; Blakely, Joseph; Ziemer, John

2013-01-01

Accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and one of the most difficult measurements to make. The American Institute of Aeronautics and Astronautics has started an initiative to develop standards for many important measurement processes in electric propulsion, including thrust measurements. This paper summarizes recommended practices for the design, calibration, and operation of pendulum thrust stands, which are widely recognized as the best approach for measuring micro N- to mN-level thrust and micro Ns-level impulse bits. The fundamentals of pendulum thrust stand operation are reviewed, along with its implementation in hanging pendulum, inverted pendulum, and torsional balance configurations. Methods of calibration and recommendations for calibration processes are presented. Sources of error are identified and methods for data processing and uncertainty analysis are discussed. This review is intended to be the first step toward a recommended practices document to help the community produce high quality thrust measurements.

AmeriFlux US-PFa Park Falls/WLEF

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

Desai, Ankur

This is the AmeriFlux version of the carbon flux data for the site US-PFa Park Falls/WLEF. Site Description - The flux footprint encompasses a highly heterogeneous landscape of upland forests and wetlands (forested and nonforested). The forests are mainly deciduous but also include substantial coniferous coverage. The upland/lowland variability occurs on spatial scales of a few hundred meters. This heterogeneous landscape is further complicated by a nonuniform, small scale mosaic of thinning and clearcutting of the forest. At larger scales (1 km or greater) the forest cover mosaic is quite homogeneous for many kilometers. The site was chosen not formore » study of a simple stand, but for upscaling experiments. The daytime fetch of flux measurements from the 396m level is on the order of 5-10 km, yielding a flux footprint roughly 100x the area of a typical stand-level flux tower. AC power (tower is a TV transmitter).« less

Vigour in West African Dwarf kids within the first 24 h post-partum.

PubMed

Abdul-Rahman, I I; Bernard, A

2017-03-01

One hundred and fifty West African Dwarf (WAD) kids were tested at the National Goats Breeding Station to determine the effects of some neonatal factors on their vigour levels within the first 24 h post-partum. The kids were also tested to establish the relationship between maternal weight, rectal temperature, times of first standing and sucking, sucking period and vigour. The distance covered (in meters) by a kid towards its mother during a 5-min test period was considered as vigour trait. Vigour levels increased significantly (p < 0.05) with increasing age within the first 24 h post-partum. Kids born to second parity mothers had higher (p < 0.05) vigour than those born to first parity mothers. Similarly, high birth weight kids had higher (p < 0.05) vigour levels than low birth weight kids. Weak positive and negative correlations (p < 0.05), respectively, were found between vigour and rectal temperature, and vigour and the time of first successfully standing. However, there was moderate positive correlation (p < 0.01) between vigour and sucking period. The time it took for the newborn kid to stand up for the first time also correlated weakly and negatively (p < 0.01) with the duration of sucking by the newborn within the first 5 min of accessing the teat. Vigour within the first 24 h post-partum in WAD kids increased with increasing age, parity and birth weight and might be responsible for the earlier and longer sucking time and periods, respectively, in high birth weight kids and those dropped by multiparous does.

Predicted effects of prescribed burning and harvesting on forest recovery and sustainability in southwest Georgia, USA.

PubMed

Garten, Charles T

2006-12-01

A model-based analysis of the effect of prescribed burning and forest thinning or clear-cutting on stand recovery and sustainability was conducted at Fort Benning, GA, in the southeastern USA. Two experiments were performed with the model. In the first experiment, forest recovery from degraded soils was predicted for 100 years with or without prescribed burning. In the second experiment simulations began with 100 years of predicted stand growth, then forest sustainability was predicted for an additional 100 years under different combinations of prescribed burning and forest harvesting. Three levels of fire intensity (low, medium, and high), that corresponded to 17%, 33%, and 50% consumption of the forest floor C stock by fire, were evaluated at 1-, 2-, and 3-year fire return intervals. Relative to the control (no fire), prescribed burning with a 2- or 3-year return interval caused only a small reduction in predicted steady state soil C stocks (< or =25%) and had no effect on steady state tree wood biomass, regardless of fire intensity. Annual high intensity burns did adversely impact forest recovery and sustainability (after harvesting) on less sandy soils, but not on more sandy soils that had greater N availability. Higher intensity and frequency of ground fires increased the chance that tree biomass would not return to pre-harvest levels. Soil N limitation was indicated as the cause of unsustainable forests when prescribed burns were too frequent or too intense to permit stand recovery.

Southern pine beetle in loblolly pine: simulating within stand interactions using the process model SPBLOBTHIN

Treesearch

Brian Strom; J. R. Meeker; J. Bishir; James Roberds; X. Wan

2016-01-01

Pine stand density is a key determinant of damage resulting from attacks by the southern pine beetle (SPB, Dendroctonus frontalis Zimm.). High-density stands of maturing loblolly pine (Pinus taeda L.) are at high risk for losses to SPB, and reducing stand density is the primary tool available to forest managers for preventing and mitigating damage. Field studies are...

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

PubMed

Stevens, Jens T; Safford, Hugh D; North, Malcolm P; Fried, Jeremy S; Gray, Andrew N; Brown, Peter M; Dolanc, Christopher R; Dobrowski, Solomon Z; Falk, Donald A; Farris, Calvin A; Franklin, Jerry F; Fulé, Peter Z; Hagmann, R Keala; Knapp, Eric E; Miller, Jay D; Smith, Douglas F; Swetnam, Thomas W; Taylor, Alan H

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data.

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America

PubMed Central

Stevens, Jens T.; Safford, Hugh D.; North, Malcolm P.; Fried, Jeremy S.; Gray, Andrew N.; Brown, Peter M.; Dolanc, Christopher R.; Dobrowski, Solomon Z.; Falk, Donald A.; Farris, Calvin A.; Franklin, Jerry F.; Fulé, Peter Z.; Hagmann, R. Keala; Knapp, Eric E.; Miller, Jay D.; Smith, Douglas F.; Swetnam, Thomas W.; Taylor, Alan H.

2016-01-01

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the “stand age” variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical “mixed-severity” fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data. PMID:27196621

Conserving old-growth forest diversity in disturbance-prone landscapes.

PubMed

Spies, Thomas A; Hemstrom, Miles A; Youngblood, Andrew; Hummel, Susan

2006-04-01

A decade after its creation, the Northwest Forest Plan is contributing to the conservation of old-growth forests on federal land. However the success and outlook for the plan are questionable in the dry provinces, where losses of old growth to wildfire have been relatively high and risks of further loss remain. We summarize the state of knowledge of old-growth forests in the plan area, identify challenges to conserve them, and suggest some conservation approaches that might better meet the goals of the plan. Historically, old-growth forests in these provinces ranged from open, patchy stands, maintained by frequent low-severity fire, to a mosaic of dense and open stands maintained by mixed-severity fires. Old-growth structure and composition were spatially heterogeneous, varied strongly with topography and elevation, and were shaped by a complex disturbance regime of fire, insects, and disease. With fire suppression and cutting of large pines (Pinus spp.) and Douglas-firs (Pseudotsuga menziesii [Mirbel] Franco), old-growth diversity has declined and dense understories have developed across large areas. Challenges to conserving these forests include a lack of definitions needed for planning of fire-dependent old-growth stands and landscapes, and conflicts in conservation goals that can be resolved only at the landscape level. Fire suppression has increased the area of the dense, older forest favored by Northern Spotted Owls (Strix occidentalis caurina) but increased the probability of high-severity fire. The plan allows for fuel reduction in late-successional reserves; fuel treatments, however apparently have not happened at a high enough rate or been applied in a landscape-level approach. Landscape-level strategies are needed that prioritize fuel treatments by vegetation zones, develop shaded fuel breaks in strategic positions, and thin and apply prescribed fire to reduce ladder fuels around remaining old trees. Evaluations of the current and alternative strategies are needed to determine whether the current reserve-matrix approach is the best strategy to meet plan goals in these dynamic landscapes.

Highly stocked coniferous stands on the Olympic Peninsula: chemical composition and implications for harvest strategy.

Treesearch

Susan N. Little; Dale R. Waddell

1987-01-01

This report presents an assessment of macronutrients and their distribution within highly stocked, stagnant stands of mixed conifers on the Quilcene Ranger District, Olympic National Forest, northwest Washington. These stands consisted of predominantly three species: western hemlock (Tsuga heterophylla (Raf.) Sarg.), coast Douglas-fir (...

Developing silvicultural systems based on partial cutting in western hemlock–Sitka spruce stands of southeast Alaska.

Treesearch

Robert L. Deal; J.C. Tappeiner; Paul E. Hennon

2002-01-01

The effects of partial cutting on species composition, stand structure and growth, tree size distribution, and tree disease and mortality were evaluated on 73 plots in 18 stands that were harvested 12–96 years ago in southeast Alaska. Partially-cut stands had diverse and highly complex stand structures similar to uncut stands. Sitka spruce was maintained in mixed...

Ten-Year Performance of Eastern White Pine - under a Crop Tree Release Regime on an Outwash Site

Treesearch

Kenneth M. Desmarais; William B. Leak; William B. Leak

2005-01-01

A young stand of eastern white pine aged 38-40 years received a crop tree release cutting reducing stocking to 100 tree/ac. This stocking level reflects the number of sterms per acre that would be contained in a well stocked mature stand at final harvest (20-in. quadratic mean stand diameter). The stand then was monitored for growth and value change. Stems that grew...

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands - III. Natural Stands Cutover 15 Years Previously but Unmanaged

Treesearch

James B. Baker; Michael G. Shelton

1998-01-01

Plots in an unmanaged loblolly-shortleaf pine (Pinus taeda L.-P. echinata Mill.) stand that had been cutover 15 yr previously were established to represent five stocking levels: 10, 20, 30, 40, and 50%. The stand was on a good site (site indexLob = 90 ft at 50 yr) and had uneven-aged character. Two competition control treatments (none and individual tree release using...

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands - IV. Natural and Planted Seedling/Sapling Stands

Treesearch

James B. Baker; Michael G. Shelton

1998-01-01

A 3- to 6 yr-old naturally regenerated, even-aged loblollypine (Pinus taeda L.) stand and a 5- yr-old loblolly pine plantation on good sites (SIbb = 85 to 90 ft at 50 yr ) were cut to density levels of 50, 90, 180,270, and 360 seedlings and/or saplings/ac. Two pine release treatments (none and individual tree release with a herbicide) were applied to the natural stand...

Impacts of abrupt climate changes in the Levant from Last Glacial Dead Sea levels

NASA Astrophysics Data System (ADS)

Torfstein, Adi; Goldstein, Steven L.; Stein, Mordechai; Enzel, Yehouda

2013-06-01

A new, detailed lake level curve for Lake Lisan (the Last Glacial Dead Sea) reveals a high frequency of abrupt fluctuations during Marine Isotope Stage 3 (MIS3) compared to the relatively high stand characterizing MIS2, and the significantly lower Holocene lake. The lake level fluctuations reflect the hydrological conditions in the large watershed of the lake, which in turn reflects the hydro-climatic conditions in the central Levant region. The new curve shows that the fluctuations coincide on millennial timescales with temperature variations recorded in Greenland. Four patterns of correlation are observed through the last ice age: (1) maximum lake elevations were reached during MIS2, the coldest interval; (2) abrupt lake level drops to the lowest elevations coincided with the occurrence of Heinrich (H) events; (3) the lake returned to higher-stand conditions along with warming in Greenland that followed H-events; (4) significant lake level fluctuations coincided with virtually every Greenland stadial-interstadial cycle. Over glacial-interglacial time-scales, Northern Hemisphere glacial cooling induces extreme wetness in the Levant, with high lake levels reaching ˜160 m below mean sea level (mbmsl), approximately 240 m above typical Holocene levels of ˜400 mbmsl. These orbital time-scale shifts are driven by expansions of the European ice sheet, which deflect westerly storm tracks southward to the Eastern Mediterranean, resulting in increased sea-air temperature gradients that invoke increased cyclogenesis, and enhanced moisture delivery to the Levant. The millennial-scale lake level drops associated with Greenland stadials are most extreme during Heinrich stadials and reflect abrupt cooling of the Eastern Mediterranean atmosphere and sea-surface, which weaken the cyclogenic rain engine and cause extreme Levant droughts. During the recovery from the effect of Heinrich stadials, the regional climate configuration resumed typical glacial conditions, with enhanced Levant precipitation and a rise in Lake Lisan levels. Similar cyclicity in the transfer of moisture to the Levant affected lake levels during all of the non-Heinrich stadial-interstadial cycles.

Monitoring forest land from high altitude and from space

NASA Technical Reports Server (NTRS)

1971-01-01

Forest inventory, forest stress, and standardization and calibration studies are presented. These include microscale photointerpretation of forest and nonforest land classes, multiseasonal film densities for automated forest and nonforest land classification, trend and spread of bark beetle infestations from 1968 through 1971, aerial photography for determining optimum levels of stand density to reduce such infestations, use of airborne spectrometers and multispectral scanners for previsual detection of Ponderosa pine trees under stress from insects and diseases, establishment of an earth resources technology satellite test site in the Black Hills and the identification of natural resolution targets, detection of root disease impact on forest stands by sequential orbital and suborbital multispectral photography, and calibration of color aerial photography.

Conservation value of low-productivity forests measured as the amount and diversity of dead wood and saproxylic beetles.

PubMed

Hämäläinen, Aino; Strengbom, Joachim; Ranius, Thomas

2018-06-01

In many managed landscapes, low-productivity land comprises most of the remaining relatively untouched areas, and is often over-represented within protected areas. The relationship between the productivity and conservational value of a site is poorly known; however, it has been hypothesized that biodiversity increases with productivity due to higher resource abundance or heterogeneity, and that the species communities of low-productivity land are a nested subset of communities from more productive land. We tested these hypotheses for dead-wood-dependent beetles by comparing their species richness and composition, as well as the amount and diversity of dead wood, between low-productivity (potential forest growth <1 m 3 ·ha -1 ·yr -1 ) and high-productivity Scots pine-dominated stands in Sweden. We included four stand types: stands situated on (1) thin soils and (2) mires (both low-productivity), (3) managed stands, and (4) unmanaged stands set aside for conservation purposes (both high-productivity). Beetle species richness and number of red-listed species were highest in the high-productivity set-asides. Species richness was positively correlated with the volume and diversity of dead wood, but volume appeared to be a better predictor than diversity for the higher species richness in set-asides. Beetle species composition was similar among stand types, and the assemblages in low-productivity stands were largely subsets of those in high-productivity set-asides. However, 11% of all species and 40% of red-listed species only occurred in high-productivity stands, while no species were unique to low-productivity stands. We conclude that low-productivity forests are less valuable for conservation than high-productivity forest land. Given the generally similar species composition among stand types, a comparable conservational effect could be obtained by setting aside a larger area of low-productivity forest in comparison to the high-productivity. In terms of dead wood volumes, 1.8-3.6 ha of low-productivity forest has the same value as 1 ha of unmanaged high-productivity forest. This figure can be used to estimate the conservation value of low-productivity forests; however, as high-productivity forests harbored some unique species, they are not completely exchangeable. © 2018 The Authors. Ecological Applications published by Wiley Periodicals, Inc. on behalf of Ecological Society of America.

Positive edge effects on forest-interior cryptogams in clear-cuts.

PubMed

Caruso, Alexandro; Rudolphi, Jörgen; Rydin, Håkan

2011-01-01

Biological edge effects are often assessed in high quality focal habitats that are negatively influenced by human-modified low quality matrix habitats. A deeper understanding of the possibilities for positive edge effects in matrix habitats bordering focal habitats (e.g. spillover effects) is, however, essential for enhancing landscape-level resilience to human alterations. We surveyed epixylic (dead wood inhabiting) forest-interior cryptogams (lichens, bryophytes, and fungi) associated with mature old-growth forests in 30 young managed Swedish boreal forest stands bordering a mature forest of high conservation value. In each young stand we registered species occurrences on coarse dead wood in transects 0-50 m from the border between stand types. We quantified the effect of distance from the mature forest on the occurrence of forest-interior species in the young stands, while accounting for local environment and propagule sources. For comparison we also surveyed epixylic open-habitat (associated with open forests) and generalist cryptogams. Species composition of epixylic cryptogams in young stands differed with distance from the mature forest: the frequency of occurrence of forest-interior species decreased with increasing distance whereas it increased for open-habitat species. Generalists were unaffected by distance. Epixylic, boreal forest-interior cryptogams do occur in matrix habitats such as clear-cuts. In addition, they are associated with the matrix edge because of a favourable microclimate closer to the mature forest on southern matrix edges. Retention and creation of dead wood in clear-cuts along the edges to focal habitats is a feasible way to enhance the long-term persistence of epixylic habitat specialists in fragmented landscapes. The proposed management measures should be performed in the whole stand as it matures, since microclimatic edge effects diminish as the matrix habitat matures. We argue that management that aims to increase habitat quality in matrix habitats bordering focal habitats should increase the probability of long-term persistence of habitat specialists.

Biomass, production and woody detritus in an old coast redwood (Sequoia sempervirens) forest

USGS Publications Warehouse

Busing, R.T.; Fujimori, T.

2005-01-01

We examined aboveground biomass dynamics, aboveground net primary production (ANPP), and woody detritus input in an old Sequoia sempervirens stand over a three-decade period. Our estimates of aboveground biomass ranged from 3300 to 5800 Mg ha-1. Stem biomass estimates ranged from 3000 to 5200 Mg ha-1. Stem biomass declined 7% over the study interval. Biomass dynamics were patchy, with marked declines in recent tree-fall patches <0.05 ha in size. Larger tree-fall patches approaching 0.2 ha in size were observed outside the study plot. Our estimates of ANPP ranged from 6 to 14 Mg ha -1yr-1. Estimates of 7 to 10 Mg ha-1yr -1 were considered to be relatively accurate. Thus, our estimates based on long-term data corroborated the findings of earlier short-term studies. ANPP of old, pure stands of Sequoia was not above average for temperate forests. Even though production was potentially high on a per stem basis, it was moderate at the stand level. We obtained values of 797 m3 ha -1 and 262 Mg ha-1 for coarse woody detritus volume and mass, respectively. Fine woody detritus volume and mass were estimated at 16 m3 ha-1 and 5 Mg ha-1, respectively. Standing dead trees (or snags) comprised 7% of the total coarse detritus volume and 8% of the total mass. Coarse detritus input averaged 5.7 to 6.9 Mg ha -1yr-1. Assuming steady-state input and pool of coarse detritus, we obtained a decay rate constant of 0.022 to 0.026. The old-growth stand of Sequoia studied had extremely high biomass, but ANPP was moderate and the amount of woody detritus was not exceptionally large. Biomass accretion and loss were not rapid in this stand partly because of the slow population dynamics and low canopy turnover rate of Sequoia at the old-growth stage. Nomenclature: Hickman (1993). ?? Springer 2005.

Positive Edge Effects on Forest-Interior Cryptogams in Clear-Cuts

PubMed Central

Caruso, Alexandro; Rudolphi, Jörgen; Rydin, Håkan

2011-01-01

Biological edge effects are often assessed in high quality focal habitats that are negatively influenced by human-modified low quality matrix habitats. A deeper understanding of the possibilities for positive edge effects in matrix habitats bordering focal habitats (e.g. spillover effects) is, however, essential for enhancing landscape-level resilience to human alterations. We surveyed epixylic (dead wood inhabiting) forest-interior cryptogams (lichens, bryophytes, and fungi) associated with mature old-growth forests in 30 young managed Swedish boreal forest stands bordering a mature forest of high conservation value. In each young stand we registered species occurrences on coarse dead wood in transects 0–50 m from the border between stand types. We quantified the effect of distance from the mature forest on the occurrence of forest-interior species in the young stands, while accounting for local environment and propagule sources. For comparison we also surveyed epixylic open-habitat (associated with open forests) and generalist cryptogams. Species composition of epixylic cryptogams in young stands differed with distance from the mature forest: the frequency of occurrence of forest-interior species decreased with increasing distance whereas it increased for open-habitat species. Generalists were unaffected by distance. Epixylic, boreal forest-interior cryptogams do occur in matrix habitats such as clear-cuts. In addition, they are associated with the matrix edge because of a favourable microclimate closer to the mature forest on southern matrix edges. Retention and creation of dead wood in clear-cuts along the edges to focal habitats is a feasible way to enhance the long-term persistence of epixylic habitat specialists in fragmented landscapes. The proposed management measures should be performed in the whole stand as it matures, since microclimatic edge effects diminish as the matrix habitat matures. We argue that management that aims to increase habitat quality in matrix habitats bordering focal habitats should increase the probability of long-term persistence of habitat specialists. PMID:22114728

Nesting ecology of boreal forest birds following a massive outbreak of spruce beetles

USGS Publications Warehouse

Matsuoka, S.M.; Handel, C.M.

2007-01-01

We studied breeding dark-eyed juncos (Junco hyemalis), yellow-rumped warblers (Dendroica coronata), and spruce-nesting birds from 1997 to 1998 among forests with different levels of spruce (Picea spp.) mortality following an outbreak of spruce beetles (Dendroctonus rufipennis) in Alaska, USA. We identified species using live and beetle-killed spruce for nest sites and monitored nests to determine how the outbreak influenced avian habitat selection and reproduction. We tested predictions that 1) nesting success of ground-nesting juncos would increase with spruce mortality due to proliferation of understory vegetation available to conceal nests from predators, 2) nesting success of canopy-nesting warblers would decrease with spruce mortality due to fewer live spruce in which to conceal nests, and 3) both species would alter nest-site selection in response to disturbance. Juncos did not benefit from changes in understory vegetation; nesting success in highly disturbed stands (46%) was comparable to that in undisturbed habitats throughout their range. In stands with low spruce mortality, nesting success of juncos was low (5%) and corresponded with high densities of red squirrels (Tamiasciurus hudsonicus). Yellow-rumped warblers nested exclusively in spruce, but success did not vary with spruce mortality. As disturbance increased, nesting warblers switched from selecting forest patches with high densities of live white spruce (Picea glauca) to patches with beetle-killed spruce. Warblers also placed nests in large-diameter live or beetle-killed spruce, depending on which was more abundant in the stand, with no differences in nesting success. Five of the 12 other species of spruce-nesting birds also used beetle-killed spruce as nest sites. Because beetle-killed spruce can remain standing for >50 years, even highly disturbed stands provide an important breeding resource for boreal forest birds. We recommend that boreal forest managers preserve uncut blocks of infested forest within managed forest landscapes and practice partial harvest of beetle-killed spruce rather than commercial clear-cutting of infested stands in order to sustain breeding bird populations until natural reforestation occurs. Because breeding densities do not always reflect fitness, assessing impacts of a massive natural disturbance should include measuring impacts of changes in vegetation on both reproductive success and predator–prey dynamics.

Evaluation of the airborne imaging spectrometer for remote sensing of forest stand conditions

NASA Technical Reports Server (NTRS)

Olson, Charles E., Jr.

1986-01-01

Five pairs of plots were established in forest stands with one of each pair trenched and covered to prevent precipitation from reaching the tree roots. High winds and falling limbs destroyed the covers on three of the plots. The two remaining plots were in a red pine plantation and in a natural stand of sugar maple. Trees in both plots developed levels of moisture stress more than nine bars higher than control trees on the dates of overflights with the Airborne Imaging Spectrometer (AIS) and the Collins' Airborne Spectroradiometer (CAS). Hemispherical reflectance from stressed and control trees was measured with a Beckman DK2A spectrophotometer. On the day of the AIS overflight, stressed maple foliage was less reflective than the control from 1000 to 1300 nm, but more reflective at wavelengths longer than 1300 nm. Pine foliage was less reflective than the control from 1000 to 1600 nm, but the difference was small at wavelengths longer than 1350 nm. AIS data collected showed brightness values for both maple and pine to be lower than for the controls from 1000 to 1300 nm. CAS data were used to determine the gain in species identification accuracy obtainable with high spectral resolution data.

Thinning and burning result in low-level invasion by nonnative plants but neutral effects on natives.

PubMed

Nelson, Cara R; Halpern, Charles B; Agee, James K

2008-04-01

Many historically fire-adapted forests are now highly susceptible to damage from insects, pathogens, and stand-replacing fires. As a result, managers are employing treatments to reduce fuel loadings and to restore the structure, species, and processes that characterized these forests prior to widespread fire suppression, logging, and grazing. However, the consequences of these activities for understory plant communities are not well understood. We examined the effects of thinning and prescribed fire on plant composition and diversity in Pinus ponderosa forests of eastern Washington (USA). Data on abundance and richness of native and nonnative plants were collected in 70 stands in the Colville, Okanogan, and Wenatchee National Forests. Stands represented one of four treatments: thinning, burning, thinning followed by burning, or control; treatments had been conducted 3-19 years before sampling. Multi-response permutation procedures revealed no significant effect of thinning or burning on understory plant composition. Similarly, there were no significant differences among treatments in cover or richness of native plants. In contrast, nonnative plants showed small, but highly significant, increases in cover and richness in response to both thinning and burning. In the combined treatment, cover of nonnative plants averaged 2% (5% of total plant cover) but did not exceed 7% (16% of total cover) at any site. Cover and richness of nonnative herbs showed small increases with intensity of disturbance and time since treatment. Nonnative plants were significantly less abundant in treated stands than on adjacent roadsides or skid trails, and cover within these potential source areas explained little of the variation in abundance within treated stands. Although thinning and burning may promote invasion of nonnative plants in these forests, our data suggest that their abundance is limited and relatively stable on most sites.

A-3 Test Stand

NASA Image and Video Library

2012-06-08

A tethered Stennis Space Center employee climbs an A-3 Test Stand ladder June 8, 2012, against the backdrop of the A-2 and B-1/B-2 stands. The new A-3 Test Stand will enable simulated high-altitude testing of next-generation rocket engines.

A-3 Test Stand

NASA Image and Video Library

2012-06-08

A tethered Stennis Space Center employee climbs an A-3 Test Stand ladded June 8, 2012, against the backdrop of the A-2 and B-1/B-2 stands. The new A-3 Test Stand will enable simulated high-altitude testing of next-generation rocket engines.

Enforcement of College Trustees' Fiduciary Duties: Students and the Problem of Standing

ERIC Educational Resources Information Center

Berry, Charles R.; Buchwald, Gerald J.

1974-01-01

In most states only the attorney general has standing to challenge the propriety of fiduciary decisions made by university trustees. Analyzes this rule and demonstrates that the present level of attorney general enforcement is inadequate. It is argued that certain representative student groups should also be accorded standing. (Editor/PG)

Characteristics of gaps and natural regeneration in mature longleaf pine flatwoods ecosystems

Treesearch

Jennifer L. Gagnon; Eric J. Jokela; W.K. Moser; Dudley A. Huber

2004-01-01

Developing uneven-aged structure in mature stands of longleaf pine requires scientifically based silvicultural systems that are reliable, productive and sustainable. Understanding seedling responses to varying levels of site resource availability within forest gaps is essential for effectively converting even-aged stands to uneven-aged stands. A project was initiated...

Functional groups show distinct differences in nitrogen cycling during early stand development: implications for forest management.

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

Aubrey, Doug, P.; Coyle, David, R. Coleman, Mark, D.

2011-08-26

Nutrient acquisition of forest stands is controlled by soil resource availability and belowground production, but tree species are rarely compared in this regard. Here, we examine ecological and management implications of nitrogen (N) dynamics during early forest stand development in productive commercial tree species with narrow (Populus deltoides Bartr. and Platanus occidentalis L.) and broad (Liquidambar styraciflua L. and Pinus taeda L.) site requirements while grown with a range of nutrient and water resources. We constructed N budgets by measuring N concentration ([N]) and N content (N{sub C}) of above- and belowground perennial and ephemeral tissues, determined N uptake (N{submore » UP}), and calculated N use efficiency (NUE). Forest stands regulated [N] within species-specific operating ranges without clear temporal or treatment patterns, thus demonstrating equilibrium between tissue [N] and biomass accumulation. Forest stand N{sub C} and N{sub UP} increased with stand development and paralleled treatment patterns of biomass accumulation, suggesting productivity is tightly linked to N{sub UP}. Inclusion of above- and belowground ephemeral tissue turnover in N{sub UP} calculations demonstrated that maximum N demand for narrow-sites adapted species exceeded 200 kg N ha{sup -1} year{sup -1} while demand for broad-site adapted species was below this level. NUE was species dependent but not consistently influenced by N availability, suggesting relationships between NUE and resource availability were species dependent. Based on early stand development, species with broad site adaptability are favored for woody cropping systems because they maintain high above- and belowground productivity with minimal fertilization requirements due to higher NUE than narrow site adapted species.« less

Megatsunami Generation From Giant Submarine Landslides on Oceanic Islands: New Insights Gained From the Hawaii Evidence and Modeling

NASA Astrophysics Data System (ADS)

McMurtry, G. M.; Tappin, D. R.; Fryer, G. J.; Watts, P.

2003-12-01

High-elevation marine gravels on the Hawaiian islands of Lanai and Molokai either mark uplifted shorelines or are deposits from massive tsunamis. The subsidence history of those islands has been too ambiguous to differentiate these causes, leading to controversy over the deposit's origins and to confusion over the impacts, or even the existence of megatsunamis generated from giant submarine landslides (GSL) mapped offshore. U-series ages of these deposits that correlate with sealevel high stands have added to the confusion. Landslide tsunami simulations have now advanced to the point where the tsunamigenic potential of GSLs can be affirmed. We show that megatsunamis are a sufficient explanation for the observed pattern of debris height of calcareous marine deposits on the southeast Hawaiian islands. Further, our tsunami simulations, using the Alika GSL as example, can be used to reduce the considerable uncertainty in subsidence history of the different Hawaiian islands. Modeled runups of 800 m occurred directly landward of the Alika 2 slide on west Hawaii and were up to 300 m on west Lanai, in agreement with previous deposit estimates there (Moore & Moore, 1984, 1988). Recently, we rediscovered calcareous marine deposits on Kohala volcano on Hawaii island, where continuous subsidence is well established from its stairway of submerged reefs. On Kohala, we found a marine fossiliferous basalt boulder conglomerate from 1.5 to 61 m above present sea level exposed at the coast and up to 1 km inland. U-series dates of corals from the deposit are approximately the same age, 100 to 120 ka, as the giant Alika 2 landslide from nearby Mauna Loa volcano, directly dated using sediment stratigraphy (McMurtry et al., 1999). The present depth of the 120-ka shoreline implies that the deposit was left by a tsunami whose runup at 6 km inland exceeded 490 m. For the late Pleistocene, large volcanic failures and exposed marine deposits both correlate foremost with sea level high stands, and in particular with the onset of interglacial conditions that are reflected in Hawaii by the apex ages of the low-stand fringing reefs. We show that such large volcanic failures inevitably generate megatsunamis, and we conclude that persistent climate effects during sea level high stands eventually unleash large volcanic failures and megatsunamis amongst the Hawaiian islands and perhaps all volcanically active oceanic islands, with invariable propagation toward the continental coasts.

Army Officer Counseling Training for Commanders: Participant Manual

DTIC Science & Technology

2011-04-01

but also create high levels of stress , burnout , and frustration. o Even social events may be perceived as burdensome because they take away from... level of security is not always present in private-sector jobs . o Educational opportunities stand out as the most attractive benefit the Army offers...and one or more silent observers. If you are an observer, your role will be to take notes on the counselor‟s performance and provide feedback at the

Microscopic Optical Characterization of Free Standing III-Nitride Substrates, ZnO Bulk Crystals, and III-V Structures for Non-Linear Optics. Part 2

DTIC Science & Technology

2010-05-18

strong radiation hardness of ZnO. Positron annihilation studies have revealed the presence of Zn vacancies under high energy electron irradiation, as...SUPPLEMENTARY NOTES 14. ABSTRACT CL study of ammonothermal GaN crystals. Preliminary results on ammonothermal AlGaN crystals show a clear...prevalence of deep level luminescence Study of the luminescence spectral characteristics. Optimization of the excitonic emission vs deep level emission

Forest lepidopteran communities are more resilient to shelterwood harvests compared to more intensive logging regimes.

PubMed

Summerville, Keith S

2013-07-01

A common measure of ecosystem resilience is the time course to recovery for a system that has been previously disturbed. The goal of this study was to assess whether forest lepidopteran communities displayed three different forms of resilience following experimental timber harvest. Specifically, I examined whether moth species assemblages returned to pre-logging composition (compositional resilience), species richness (structural resilience), and guild diversity (functional resilience) after forest management. Lepidoptera were sampled from 16 forest stands managed with one of four harvest treatments: no logging, clear-cutting, shelterwood harvests, and group selection harvests. Moths were sampled from all forest stands one year prior to harvest in 2007 and immediately postharvest in 2009-2011. Moth community composition only appeared to be resilient to timber harvest in stands managed with shelterwood methods (15% biomass removed) or in the unlogged stands within managed concession units. Both total species richness and species richness of Quercus-feeding moths also appeared to recover to a near original condition three years post-shelterwood logging. In contrast, moth assemblages in clear-cut stands and group selection stands (80% biomass removed) remained impoverished. Tests of functional resilience suggested that richness of species known to be pollinators was largely unaffected by timber management, and the number of moth species known to feed on herbaceous vegetation doubled in stands logged using group selection methods. Dietary specialists were disproportionately abundant in the unlogged stands postharvest, suggesting that species with more narrow dietary niches have the lowest resilience to timber management. These results suggest that most methods of forest management have short-term negative impacts on woody-plant-feeding Lepidoptera, but that the effects are limited to a few years when the harvest method involves shelterwood cuts. Herbaceous-feeding Lepidoptera appear to quickly colonize stands managed with group selection or clear-cutting, so loss of species richness in stands managed with either of these treatments may be less than predicted based on level of timber being removed. Recovery of moth assemblages in more highly disturbed stands will require longer time periods and techniques such as group selection harvests, where upwards of 80% of the standing bole is removed, may not be consistent with conservation goals.

Hyperspectral and multispectral satellite sensors for mapping chlorophyll content in a Mediterranean Pinus sylvestris L. plantation

NASA Astrophysics Data System (ADS)

Navarro-Cerrillo, Rafael Mª; Trujillo, Jesus; de la Orden, Manuel Sánchez; Hernández-Clemente, Rocío

2014-02-01

A new generation of narrow-band hyperspectral remote sensing data offers an alternative to broad-band multispectral data for the estimation of vegetation chlorophyll content. This paper examines the potential of some of these sensors comparing red-edge and simple ratio indices to develop a rapid and cost-effective system for monitoring Mediterranean pine plantations in Spain. Chlorophyll content retrieval was analyzed with the red-edge R750/R710 index and the simple ratio R800/R560 index using the PROSPECT-5 leaf model and the Discrete Anisotropic Radiative Transfer (DART) and experimental approach. Five sensors were used: AHS, CHRIS/Proba, Hyperion, Landsat and QuickBird. The model simulation results obtained with synthetic spectra demonstrated the feasibility of estimating Ca + b content in conifers using the simple ratio R800/R560 index formulated with different full widths at half maximum (FWHM) at the leaf level. This index yielded a r2 = 0.69 for a FWHM of 30 nm and r2 = 0.55 for a FWHM of 70 nm. Experimental results compared the regression coefficients obtained with various multispectral and hyperspectral images with different spatial resolutions at the stand level. The strongest relationships where obtained using high-resolution hyperspectral images acquired with the AHS sensor (r2 = 0.65) while coarser spatial and spectral resolution images yielded a lower root mean square error (QuickBird r2 = 0.42; Landsat r2 = 0.48; Hyperion r2 = 0.56; CHRIS/Proba r2 = 0.57). This study shows the need to estimate chlorophyll content in forest plantations at the stand level with high spatial and spectral resolution sensors. Nevertheless, these results also show the accuracy obtained with medium-resolution sensors when monitoring physiological processes. Generating biochemical maps at the stand level could play a critical rule in the early detection of forest decline processes enabling their use in precision forestry.

Total carbon and nitrogen in mineral soil after 26 years of prescribed fire: Long Valley and Fort Valley Experimental Forests (P-53)

Treesearch

Daniel G. Neary; Sally M. Haase; Steven T. Overby

2008-01-01

Prescribed fire was introduced to high density ponderosa pine stands at Fort Valley and Long Valley Experimental Forests in 1976. This paper reports on mineral soil total carbon (C) and nitrogen (N) at Long Valley. Total soil C and N levels were highly variable and exhibited an increasing, but inconsistent, concentration trend related to burn interval. Total N ranged...

An unsupervised two-stage clustering approach for forest structure classification based on X-band InSAR data - A case study in complex temperate forest stands

NASA Astrophysics Data System (ADS)

Abdullahi, Sahra; Schardt, Mathias; Pretzsch, Hans

2017-05-01

Forest structure at stand level plays a key role for sustainable forest management, since the biodiversity, productivity, growth and stability of the forest can be positively influenced by managing its structural diversity. In contrast to field-based measurements, remote sensing techniques offer a cost-efficient opportunity to collect area-wide information about forest stand structure with high spatial and temporal resolution. Especially Interferometric Synthetic Aperture Radar (InSAR), which facilitates worldwide acquisition of 3d information independent from weather conditions and illumination, is convenient to capture forest stand structure. This study purposes an unsupervised two-stage clustering approach for forest structure classification based on height information derived from interferometric X-band SAR data which was performed in complex temperate forest stands of Traunstein forest (South Germany). In particular, a four dimensional input data set composed of first-order height statistics was non-linearly projected on a two-dimensional Self-Organizing Map, spatially ordered according to similarity (based on the Euclidean distance) in the first stage and classified using the k-means algorithm in the second stage. The study demonstrated that X-band InSAR data exhibits considerable capabilities for forest structure classification. Moreover, the unsupervised classification approach achieved meaningful and reasonable results by means of comparison to aerial imagery and LiDAR data.

Stocking, growth, and yield of oak stands

Treesearch

Samuel F. Gingrich

1971-01-01

An appraisal of stocking in even-aged upland oak stands is a prerequisite for determining the cultural needs of a given stand. Most oak stands have sufficient stocking to utilize the site, but are deficient in high-quality trees. Thinning such stands offers a good opportunity to upgrade the relative quality of the growing stock and enhance the growth and yield...

Deer Browse Production of Oak Stands in Central Lower Michigan

Treesearch

Leslie W. Gysel; Forest Stearns

1968-01-01

The extensive oak forests of Lower Michigan provide essential habitat for whitetailed deer and other wildlife. Clearcutting these stands results in high browse production (500-1000 lbs./acre) compared to uncut stands (200-500 lbs./acre). Most browse in uncut stands is under 18 inches tall, whereas much of that in open stands is above snowline and thus available in...

Flexible integration of free-standing nanowires into silicon photonics.

PubMed

Chen, Bigeng; Wu, Hao; Xin, Chenguang; Dai, Daoxin; Tong, Limin

2017-06-14

Silicon photonics has been developed successfully with a top-down fabrication technique to enable large-scale photonic integrated circuits with high reproducibility, but is limited intrinsically by the material capability for active or nonlinear applications. On the other hand, free-standing nanowires synthesized via a bottom-up growth present great material diversity and structural uniformity, but precisely assembling free-standing nanowires for on-demand photonic functionality remains a great challenge. Here we report hybrid integration of free-standing nanowires into silicon photonics with high flexibility by coupling free-standing nanowires onto target silicon waveguides that are simultaneously used for precise positioning. Coupling efficiency between a free-standing nanowire and a silicon waveguide is up to ~97% in the telecommunication band. A hybrid nonlinear-free-standing nanowires-silicon waveguides Mach-Zehnder interferometer and a racetrack resonator for significantly enhanced optical modulation are experimentally demonstrated, as well as hybrid active-free-standing nanowires-silicon waveguides circuits for light generation. These results suggest an alternative approach to flexible multifunctional on-chip nanophotonic devices.Precisely assembling free-standing nanowires for on-demand photonic functionality remains a challenge. Here, Chen et al. integrate free-standing nanowires into silicon waveguides and show all-optical modulation and light generation on silicon photonic chips.

Do quiet standing centre of pressure measures within specific frequencies differ based on ability to recover balance in individuals with stroke?

PubMed Central

Schinkel-Ivy, Alison; Singer, Jonathan C.; Inness, Elizabeth L.; Mansfield, Avril

2016-01-01

Objective To determine whether quiet standing measures at specific frequency levels (representative of reactive control) differed between individuals with stroke based on their ability to recover balance (failed or successful responses to external perturbations). Methods Individuals with stroke completed a clinical assessment, including 30 s of quiet standing and lean-and-release postural perturbations, at admission to in-patient rehabilitation. Quiet standing centre of pressure (COP) signals were calculated and discrete wavelet decomposition was performed. Net COP amplitude, between-limb synchronization, and ratios of individual-limb COP were determined for each frequency level of interest, and for the non-decomposed signal (all frequency levels). Outcome measures were compared between individuals who exhibited failed and successful responses during a) unconstrained and b) encouraged-use lean-and-release trials. Results Individuals with failed responses during the unconstrained lean-and-release trials displayed greater net COP amplitude than those with successful responses, specifically within a frequency range of 0.40–3.20 Hz. Conclusions Reduced ability to recover balance among individuals with stroke may be reflected in impaired reactive control of quiet standing. Significance These results provide insight into the mechanism by which reactive control of quiet standing is impaired in individuals with stroke, and may inform assessment and rehabilitation strategies for post-stroke reactive balance control. PMID:27178866

Mapping spatial distribution of forest age in China

NASA Astrophysics Data System (ADS)

Zhang, Yuan; Yao, Yitong; Wang, Xuhui; Liu, Yongwen; Piao, Shilong

2017-03-01

Forest stand age is a meaningful metric, which reflects the past disturbance legacy, provides guidelines for forest management practices, and is an important factor in qualifying forest carbon cycles and carbon sequestration potential. Reliable large-scale forest stand age information with high spatial resolutions, however, is difficult to obtain. In this study, we developed a top-down method to downscale the provincial statistics of national forest inventory data into 1 km stand age map using climate data and light detection and ranging-derived forest height. We find that the distribution of forest stand age in China is highly heterogeneous across the country, with a mean value of 42.6 years old. The relatively young stand age for Chinese forests is mostly due to the large proportion of newly planted forests (0-40 years old), which are more prevailing in south China. Older forests (stand age > 60 years old) are more frequently found in east Qinghai-Tibetan Plateau and the central mountain areas of west and northeast China, where human activities are less intensive. Among the 15 forest types, forests dominated by species of Taxodiaceae, with the exception of Cunninghamia lanceolata stands, have the oldest mean stand age (136 years), whereas Pinus massoniana forests are the youngest (18 years). We further identified uncertainties associated with our forest age map, which are high in west and northeast China. Our work documents the distribution of forest stand age in China at a high resolution which is useful for carbon cycle modeling and the sustainable use of China's forest resources.

Microgravity does not alter plant stand gas exchange of wheat at moderate light levels and saturating CO2 concentration.

PubMed

Monje, O; Stutte, G; Chapman, D

2005-10-01

Plant stand gas exchange was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand gas exchange of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 micromol m(-2) s(-1)) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels.

Fiber grating systems for traffic monitoring

NASA Astrophysics Data System (ADS)

Udd, Eric; Kunzler, Marley; Laylor, Harold M.; Schulz, Whitten L.; Kreger, Stephen T.; Corones, John C.; McMahon, Robert; Soltesz, Steven M.; Edgar, Robert

2001-08-01

Blue Road Research has designed, built, and installed fiber grating sensor systems onto bridges, and most recently into an asphalt and concrete highway test pad. The sensitivity levels of the fiber grating sensors are sufficiently high to enable detection of people standing on the bridge or highway. This paper briefly overviews the usage of these sensors for traffic monitoring.

Standing Waves in an Elastic Spring: A Systematic Study by Video Analysis

ERIC Educational Resources Information Center

Rodrigues Ventura, Daniel; Simeão de Carvalho, Paulo; Adriano Dias, Marco

2017-01-01

The word "wave" is part of the daily language of every student. However, the physical understanding of the concept demands a high level of abstract thought. In physics, waves are oscillating variations of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A wave can be…

Forecasting long-term acorn production with and without oak decline using forest inventory data

Treesearch

Cathryn H. Greenberg; Chad E. Keyser; Leah C. Rathburn; Anita K. Rose; Todd M. Fearer; Henry W. McNab

2013-01-01

Acorns are important as wildlife food and for oak regeneration, but production is highly variable, posing a challenge to forest managers targeting acorn production levels. Forest managers need tools to predict acorn production capability tailored to individual landscapes and forest management scenarios, adjusting for oak mortality and stand development over time. We...

Conservation of avian diversity in the Sierra Nevada: Moving beyond a single-species management focus

Treesearch

Angela M. White; Elise F. Zipkin; Patricia N. Manley; Matthew D. Schlesinger

2013-01-01

Background: As a result of past practices, many of the dry coniferous forests of the western United States contain dense, even-aged stands with uncharacteristically high levels of litter and downed woody debris. These changes to the forest have received considerable attention as they elevate concerns regarding the outcome of wildland fire...

Barriers to Participation in Adult Literacy Programs in Kenya

ERIC Educational Resources Information Center

Muiru, John; Mukuria, Gathogo

2005-01-01

To compete internationally, adapt to new technologies, and attain higher levels of efficiency and productivity, a country needs a highly literate populace. However, in Kenya, literacy stands at less than 65% of the population. With such a low rate of literacy, most development is hampered. In order for Kenya to make progress in political, social,…

Implementing Athletic Trainers for the Management of Cheerleading Injuries

ERIC Educational Resources Information Center

Nakajima, Mikiko; Valdez, Josepha M.

2013-01-01

Cheerleading used to be about standing on the sidelines waving pom-poms. Now, cheerleaders are thrown 10 feet in the air and perform high-level gymnastics skills. For this reason, cheerleading has become the leading cause of catastrophic sport injuries in the United States. Football, which is one of the most dangerous sports, has abundant access…

The Global Challenge: Education in a Competitive World. Quality Counts, 2012

ERIC Educational Resources Information Center

Education Week, 2012

2012-01-01

"Quality Counts 2012," the 16th edition of "Education Week"'s annual examination of issues and challenges facing America's public schools, takes aim at topics high on the policy agenda, from the White House and Congress down to the level of local school boards and chambers of commerce: the nation's international standing in…

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...

Evaporation and transpiration from forests in Central Europe - relevance of patch-level studies for spatial scaling

NASA Astrophysics Data System (ADS)

Köstner, B.

Spatial scaling from patch to the landscape level requires knowledge on the effects of vegetation structure on maximum surface conductances and evaporation rates. The following paper summarizes results on atmospheric, edaphic, and structural controls on forest evaporation and transpiration observed in stands of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica). Forest canopy transpiration (Ec) was determined by tree sapflow measurements scaled to the stand level. Estimates of understory transpiration and forest floor evaporation were derived from lysimeter and chamber measurements. Strong reduction of Ec due to soil drought was only observed at a Scots pine stand when soil water content dropped below 16% v/v. Although relative responses of Ec on atmospheric conditions were similar, daily maximum rates of could differ more than 100% between forest patches of different structure (1.5-3.0mmd-1 and 2.6-6.4mmd-1 for spruce and beech, respectively). A significant decrease of Ecmax per leaf area index with increasing stand age was found for monocultures of Norway spruce, whereas no pronounced changes in were observed for beech stands. It is concluded that structural effects on Ecmax can be specified and must be considered for spatial scaling from forest stands to landscapes. Hereby, in conjunction with LAI, age-related structural parameters are important for Norway spruce stands. Although compensating effects of tree canopy layers and understory on total evaporation of forests were observed, more information is needed to quantify structure-function relationships in forests of heterogenous structure.

Knickpoint formation and landscape response following coastal cliff retreat at last-interglacial sea-level highstand: Kaua';i, Hawai';i (Invited)

NASA Astrophysics Data System (ADS)

Lamb, M. P.; Mackey, B. H.; Farley, K. A.; Scheingross, J. S.

2013-12-01

The upstream propagation of knickpoints is an important mechanism for channel incision and communicates changes in climate, sea level and tectonics throughout a landscape. Here, we use cosmogenic 3He exposure dating to document the retreat rate of a waterfall in Ka'ula'ula Valley, Kaua';i, Hawai';i, an often-used site for knickpoint-erosion modeling. Exposure ages of terraces are oldest near the coast (120 ka) and systematically decrease with upstream distance towards the waterfall (<10 ka) suggesting that the waterfall migrated 4 km over the past 120 ka at an average rate of 33 mm/yr. Upstream of the knickpoint, cosmogenic nuclide concentrations in channel are approximately uniform and indicate steady-state vertical erosion at a rate of ~0.03 mm/yr. Field observations and topographic analyses suggest that waterfall retreat is dominated by block toppling, with sediment transport below the waterfall actively occurring by debris flows. Knickpoint initiation was previously attributed to a submarine landslide ca. 4 Ma; however, our dating results, bathymetric analysis, and landscape-evolution modeling support knickpoint generation by wave-induced seacliff erosion during the last interglacial sea-level high stand. We illustrate that knickpoint generation during sea-level high stands, as opposed to the typical case of sea-level fall, is an important relief-generating mechanism on steep coasts with stable or subsiding coasts, and likely drives transient pulses of significant source-to-sink sediment flux.

Soil acidity and manganese in declining and nondeclining sugar maple stands in Pennsylvania.

PubMed

Kogelmann, Wilhelm J; Sharpe, William E

2006-01-01

For decades, the hardwood forests of northern Pennsylvania have been subjected to chronic atmospheric loading of acidifying agents. On marginal, high-elevation, unglaciated sites, sugar maples (Acer saccharum Marsh.) have experienced severe decline symptoms and mortality. Accelerated soil acidification, base cation leaching, and increased availability of toxic metals have been suggested as predisposing factors contributing to this decline. Manganese, an essential micronutrient, is also a potentially phytotoxic metal that may be a factor associated with poor sugar maple health on soils vulnerable to acidification from anthropogenic sources. We measured Mn levels in four compartments of the soil-tree system (soil, foliage, xylem wood, and sap) on three sugar maple stands in northern Pennsylvania. Two stands were classified as declining and one was in good health. Negative correlations were found between soil pH and Mn levels in the soil, foliage, sap, and xylem wood. Levels of Mn in these pools were consistently higher on declining sites, which correspondingly exhibited lower levels of Ca and Mg. Species differences between red maple (Acer rubrum L.) and sugar maple at the two declining sites suggested different tolerances to excessive Mn. Molar ratios of Mg/Mn and Ca/Mn were different among sites and showed potential as indicators of soil acidification. Significant correlations among soil, sap, foliage, and xylem wood Mn were also noted. These results show clear Mn differences among sites and, when viewed with recent Mn toxicity experiments and other observational studies, suggest that excessive Mn may play a role in the observed decline and mortality of sugar maple.

Long-term trends in loblolly pine productivity and stand characteristics in response to thinning and fertilization in the West Gulf region

Treesearch

Mary A. Sword Sayer; Jeffery C. Goelz; Jim L. Chambers; Zhenmin Tang; T.J. Dean; James D. Haywood; Daniel J. Leduc

2004-01-01

Two levels each of thinning and fertilization were applied to a 7-year-old loblolly pine (Pinus taeda L.) plantation on a nitrogen- and phosphorus-deficient West Gulf Coastal Plain site in Louisiana. Levels of thinning were no thinning, or thinning applied 7 and 14 years after stand initiation. Levels of fertilization were no fertilization or...

Estimating merchantable volumes of second growth Douglas-fir stands from total cubic volume and associated stand characteristics.

Treesearch

Richard L. Williamson; Robert O. Curtis

1980-01-01

Equations are given for estimating merchantable volumes of second-growth Douglas-fir stands to specified breast-high and top-diameter limits, in cubic feet or board feet, from total volume in cubic feet and certain associated stand characteristics.

Pilates improves lower limbs strength and postural control during quite standing in a child with hemiparetic cerebral palsy: A case report study.

PubMed

Dos Santos, Adriana Neves; Serikawa, Simoni Sayuri; Rocha, Nelci Adriana Cicuto Ferreira

2016-08-01

To verify the effect of Pilates exercises in a child with cerebral palsy (CP) with mild functional impairment. We evaluated average peak torque of ankle and knee extensors/flexors using a Biodex System, using concentric active-assisted test. We also evaluated amplitude of anterior-posterior and of medial-lateral displacement of the CoP and area of oscillation during quite standing with a BERTEC platform. We applied Pilates exercises for eight weeks. Peak torque/body weight of ankle and knee extensors/flexors of both affected and unaffected limbs increased after Pilates. Also, all kinetic variables decreased after Pilates' intervention. After one-month follow-up, isokinetic variable values were higher while kinetic variable values were lower than baseline values. Pilates may be an important rehabilitation technique for children with CP that present mild deficits in motor structures and high functional level, especially when the aims are to improve muscle strength and postural control during quite standing.

A randomized, double-blind, placebo-controlled clinical trial on the treatment of vitamin D insufficiency in postmenopausal women

PubMed Central

Hansen, Karen E.; Johnson, R. Erin; Chambers, Kaitlin R.; Johnson, Michael G.; Lemon, Christina C.; Thuy Vo, Tien Nguyen; Marvdashti, Sheeva

2015-01-01

Importance Experts debate optimal 25(OH)D levels for musculoskeletal health. Objective To compare effects of placebo, low-dose and high-dose vitamin D on one-year changes in total fractional calcium absorption, bone mineral density, Timed-Up-and-Go and 5-sit-to-stand tests and muscle mass in postmenopausal women with vitamin D insufficiency. Design Randomized, double-blind, placebo-controlled, clinical trial conducted from May 2010 to August 2014. Setting Single-center trial conducted in Madison, Wisconsin. Participants 230 postmenopausal women ≤75 years old with baseline 25(OH)D levels 14-27 ng/mL and no osteoporosis. Intervention Three arms included daily white and twice monthly yellow placebo (n=76), daily 800 IU vitamin D3 and twice monthly yellow placebo (n=76), and daily white placebo and twice monthly 50,000 IU vitamin D3 (n=79). The high-dose vitamin D regimen achieved and maintained 25(OH)D levels ≥30 ng/mL. Main Outcome Measures One year change in total fractional calcium absorption using two stable isotopes, bone mineral density and muscle mass using dual energy x-ray absorptiometry, Timed-Up-and-Go and 5-Sit-to-Stand tests, functional status (Health Assessment Questionnaire) and physical activity (Physical Activity Scale for the Elderly), with Benjamini-Hochberg correction of p-values to control the false discovery rate. Results After controlling for baseline absorption, calcium absorption increased 1% (10 mg/day) in the high-dose arm, but decreased by 2% in low-dose (p=0.005 vs. high-dose) and by 1.3% placebo (p=0.03 vs. high-dose) arms. We found no between-arm changes in spine, mean total hip, mean femoral neck or total body bone mineral density, trabecular bone score, muscle mass, 5-sit-to-stand or Timed-Up-and-Go test scores. Likewise, we found no between-arm differences for numbers of falls, number of fallers, physical activity or functional status. Conclusion and Relevance High-dose vitamin D therapy increased calcium absorption, but the effect was small and did not translate into beneficial effects on bone mineral density, muscle function, muscle mass or falls. We found no data to support experts’ recommendations to maintain serum 25(OH)D levels ≥30 ng/mL in postmenopausal women. Instead, we found that low and high-dose vitamin D were equivalent to placebo, in their effects on bone and muscle outcomes in this cohort of postmenopausal women with 25(OH)D levels <30 ng/mL. ClinicalTrials.gov.Identifier:NCT00933244 PMID:26237520

Age estimates for the late quaternary high sea-stands

NASA Astrophysics Data System (ADS)

Smart, Peter L.; Richards, David A.

A database of more than 300 published alpha-counted uranium-series ages has been compiled for coral reef terraces formed by Late Pleistocene high sea-stands. The database was screened to eliminate unreliable age estimates ( {230Th }/{232Th } < 20, calcite > 5%) and those without quoted without quoted errors, and a distributed error frequency curve was produced. This curve can be considered as a finite mixture model comprising k component normal distributions each with a weighting α. By using an expectation maximising algorithm, the mean and standard deviation of the component distributions, each corresponding to a high sea level event, were estimated. Eight high sea-stands with mean and standard deviations of 129.0 ± 33.0, 123.0 ± 13.0, 102.5 ± 2.0, 81.5 ± 5.0, 61.5 ± 6.0, 50.0 ± 1.0, 40.5 ± 5.0 and 33.0 ± 2.5 ka were resolved. The standard deviations are generally larger than the values quoted for individual age estimates. Whilst this may be due to diagenetic effects, especially for the older corals, it is argued that in many cases geological evidence clearly indicates that the high stands are multiple events, often not resolvable at sites with low rates of uplift. The uranium-series dated coral-reef terrace chronology shows good agreement with independent chronologies derived for Antarctic ice cores, although the resolution for the latter is better. Agreement with orbitally-tuned deep-sea core records is also good, but it is argued that Isotope Stage 5e is not a single event, as recorded in the cores, but a multiple event spanning some 12 ka. The much earlier age for Isotope Stage 5e given by Winograd et al. (1988) is not supported by the coral reef data, but further mass-spectrometric uranium-series dating is needed to permit better chronological resolution.

A Comparison of Fire Intensity levels for stand replacement of table mountain pine (Pinus pungens Lamb.)

Treesearch

Thomas A. Waldrop; Patrick H. Brose

1999-01-01

Stand-replacement prescribed fire has been recommended to regenerate stands of table mountain pine (Pinus pungens Lamb.) in the Southern Appalachian Mountains because the species has serotinous cones and is shade intolerant. A 350 ha prescribed fire in northeast Georgia provided an opportunity to observe overstory mortality and regeneration of table...

Effects of stand development and weather on monthly leaf biomass dynamics of a loblolly pine (Pinus taeda L.) stand

Treesearch

P.M. Dougherty; T.C. Hennessey; Stanley J. Zarnoch; P.t> Stenberg; R.T. Holeman; R.F. Witter

1995-01-01

Annual leaf biomass production, monthly needle accretion and monthly needlefall were measured in an 1l- to 17-year-old thinned stand of loblolly pine. Initial thinning levels were 7.8 m2 ha-1, 12.6 m2 ha-1, and 25.5 m2 ha-1...

Linking harvest choices to timber supply

Treesearch

Jeffrey P. Prestemon; David N. Wear

2000-01-01

Aggregate timber supply by ownership was investigated for a small region by applying stand-level harvest choice models to a representative sample of stands and then aggregating to regional totals using the area-frame of the forest survey. Timber harvest choices were estimated as probit models for three ownership categories in coastal plain southern pine stands of North...

A radiographic assessment of lumbar spine posture in four different upright standing positions.

PubMed

Gallagher, Kaitlin M; Sehl, Michael; Callaghan, Jack P

2016-08-01

Approximately 50% of a sample population will develop prolonged standing induced low back pain. The cause of this pain may be due to their lumbar spine posture. The purpose of this study was to investigate differences in lumbar posture between 17 participants categorized as a pain or non-pain developers during level ground standing. A secondary purpose was to evaluate the influence of two standing aids (an elevated surface to act as a foot rest and declined sloped surface) on lumbopelvic posture. Four sagittal plane radiographs were taken: a normal standing position on level ground, when using an elevated foot rest, using a declined sloped surface, and maximum lumbar spine extension as a reference posture. Lumbosacral lordosis, total lumbar lordosis, and L1/L2 and L5/S1 intervertebral joint angles were measured on each radiograph. There was a significant difference between the lumbosacral lordosis angle and L5/S1 angles in upright versus maximum extension; however, this was independent of pain group. The elevated surface was most effective at causing lumbosacral spine flexion. Potentially successful postures for eliminating low back pain during prolonged standing mainly influence the lower lumbar lordosis. Future work should assess the influence of hip posture on low back pain development during standing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tree diversity does not always improve resistance of forest ecosystems to drought.

PubMed

Grossiord, Charlotte; Granier, André; Ratcliffe, Sophia; Bouriaud, Olivier; Bruelheide, Helge; Chećko, Ewa; Forrester, David Ian; Dawud, Seid Muhie; Finér, Leena; Pollastrini, Martina; Scherer-Lorenzen, Michael; Valladares, Fernando; Bonal, Damien; Gessler, Arthur

2014-10-14

Climate models predict an increase in the intensity and frequency of drought episodes in the Northern Hemisphere. Among terrestrial ecosystems, forests will be profoundly impacted by drier climatic conditions, with drastic consequences for the functions and services they supply. Simultaneously, biodiversity is known to support a wide range of forest ecosystem functions and services. However, whether biodiversity also improves the resistance of these ecosystems to drought remains unclear. We compared soil drought exposure levels in a total of 160 forest stands within five major forest types across Europe along a gradient of tree species diversity. We assessed soil drought exposure in each forest stand by calculating the stand-level increase in carbon isotope composition of late wood from a wet to a dry year (Δδ(13)CS). Δδ(13)CS exhibited a negative linear relationship with tree species diversity in two forest types, suggesting that species interactions in these forests diminished the drought exposure of the ecosystem. However, the other three forest types were unaffected by tree species diversity. We conclude that higher diversity enhances resistance to drought events only in drought-prone environments. Managing forest ecosystems for high tree species diversity does not necessarily assure improved adaptability to the more severe and frequent drought events predicted for the future.

First-year results of a prescribed burn in a high-elevation red oak stand

Treesearch

Peter Bates; Dean Simon

2009-01-01

In March 2007, a prescribed burn was conducted on approximately 70 acres in a high-elevation red oak stand located on the Cold Mountain Game Land in western North Carolina. This burn was the first in a series of treatments designed to increase oak and hickory regeneration in this stand.

Silvicultural aspects intermediate cuttings

Treesearch

Kenneth L. Carvell

1971-01-01

Correct timing of the first thinning in mixed oak stands depends largely on the composition and condition of the stands and on available markets for small wood products. Delaying first thinnings in high-quality seedling-origin stands until a long, straight, clear bole has developed is of primary importance in assuring high quality of the final crop trees. However, many...

Ectomycorrhizal Community Structure and Soil Characteristics of Mature Lodgepole Pine (Pinus Contorta) and Adjacent Stands of Old Growth Mixed Conifer in Yellowstone National Park, Wyoming USA

NASA Technical Reports Server (NTRS)

Douglas, Robert B.; Parker, V. Thomas; Cullings, Kenneth W.; Sun, Sidney (Technical Monitor)

2003-01-01

Forest development patterns following disturbance are known to influence the physical and chemical attributes of soils at different points in time. Changes in soil resources are thought to have a corresponding effect on ectomycorrhizal (ECM) community structure. We used molecular methods to compare below-ground ECM species richness, composition, and abundance between adjacent stands of homogenous lodgepole pine and old growth mixed conifer in Yellowstone National Park (YNP). In each stand-type we collected soil cores to both identify mycorrhizae and assess soil chemistry. Although no statistical difference was observed in the mean number of ECM root tips per core between stand types, the total number of species identified (85 versus 35) and the mean number of species per core (8.8 +/- 0.6 versus 2.5 +/- 0.3) were significantly higher in lodgepole pine. Differences between the actual and estimated species richness levels indicated that these forest types support a high number of ECM species and that undersampling was severe. Species compositions were widely disparate between stands where only four species were shared out of a total of 116. Soil analysis also revealed that mixed conifer was significantly lower in pH, but higher in organic matter, potassium, phosphorus, and ammonium when compared to lodgepole pine stands. Species richness per core was correlated with these chemical data, however, analysis of covariance indicated that stand type was the only statistically significant factor in the observed difference in species richness. Our data suggest that ECM fungal richness increases as homogenous lodgepole pine stands grow and mature, but declines after Engelmann spruce and subalpine fir colonize. Despite difficulties linking species composition with soil chemistry, there are a variety of physical and chemical factors that could be influencing ECM community structure. Future field experiments are necessary to test some of the mechanisms potentially operating within this system.

Approximations of stand water use versus evapotranspiration from three mangrove forests in southwest Florida, USA

USGS Publications Warehouse

Krauss, Ken W.; Barr, Jordan G.; Engel, Victor C.; Fuentes, Jose D.; Wang, Hongqing

2014-01-01

Leaves from mangrove forests are often considered efficient in the use of water during photosynthesis, but less is known about whole-tree and stand-level water use strategies. Are mangrove forests as conservative in water use as experimental studies on seedlings imply? Here, we apply a simple model to estimate stand water use (S), determine the contribution of S to evapotranspiration (ET), and approximate the distribution of S versus ET over annual cycles for three mangrove forests in southwest Florida, USA. The value of S ranged from 350 to 511 mm year−1 for two mangrove forests in Rookery Bay to 872 mm year−1 for a mangrove forest along the Shark River in Everglades National Park. This represents 34–49% of ET for Rookery Bay mangroves, a rather conservative rate ofS, and 63–66% of ET for the Shark River mangroves, a less conservative rate of S. However, variability in estimates of S in mangroves is high enough to require additional study on the spatial changes related to forest structural shifts, different tidal regimes, and variable site-specific salinity concentrations in multiple mangrove forests before a true account of water use conservation strategies can be understood at the landscape scale. Evidence does suggest that large, well-developed mangrove forests have the potential to contribute considerably to the ET balance; however, regionally most mangrove forests are much smaller in stature in Florida and likely contribute less to regional water losses through stand-level transpiration.

Western spruce budworm as related to stand characteristics in the bitterroot national forest

Treesearch

Carroll B. Williams; Patrick J. Shea; Gerald S. Walton

1971-01-01

Relation of population density to certain stand conditions and damage indicators was analyzed in four drainages on the Bitterroot National Forest of Montana. Western spruce budworm (Choristoneura occidentalis Freeman) populations were strongly related to plot basal area, tree species, and tree crown levels, and also to current and past levels of tree defoliation....

Selection of roosting habitat by forest bats in a diverse forested landscape

Treesearch

Roger W. Perry; Ronald E. Thill; David M. Leslie

2007-01-01

Many studies of roost selection by forest-dwelling bats have concentrated on microhabitat surrounding roosts without providing forest stand level preferences of bats; thus, those studies have provided only part of the information needed by managers. We evaluated diurnal summer roost selection by the bat community at the forest-stand level in a diversely forested...

Modeling individual tree survial

Treesearch

Quang V. Cao

2016-01-01

Information provided by growth and yield models is the basis for forest managers to make decisions on how to manage their forests. Among different types of growth models, whole-stand models offer predictions at stand level, whereas individual-tree models give detailed information at tree level. The well-known logistic regression is commonly used to predict tree...

Not Getting Burned: The Importance of Fire

Treesearch

Gregory S. Amacher; Arun S. Malik; Robert G. Haight

2005-01-01

We extend existing stand-level models of forest landowner behavior in the presence of fire risk to include the level and timing of fuel management activities. These activities reduce losses if a stand ignites. Based on simulations, we find the standard result that fire risk reduces the optimal rotation age does not hold when landowners use fuel management. Instead,...

[Impacts of forest and precipitation on runoff and sediment in Tianshui watershed and GM models].

PubMed

Ouyang, H

2000-12-01

This paper analyzed the impacts of foret stand volume and precipitation on annual erosion modulus, mean sediment, maximum sediment, mean runoff, maximum runoff, minimum runoff, mean water level, maximum water level and minimum water level in Tianshui watershed, and also analyzed the effect of the variation of forest stand volume on monthly mean runoff, minimum runoff and mean water level. The dynamic models of grey system GM(1, N) were constructed to simulate the changes of these hydrological elements. The dynamic GM models on the impact of stand volumes of different forest types(Chinese fir, masson pine and broad-leaved forests) with different age classes(young, middle-aged, mature and over-mature) and that of precipitation on the hydrological elements were also constructed, and their changes with time were analyzed.

Ergonomic design of a barber's workstation.

PubMed

al-Haboubi, M H; Baig, A

1997-06-01

Long hours of work while standing have been known to cause health problems for humans. Such professions include that of the barber. A survey was conducted of barbers from different barber shops in Saudi Arabia to determine their discomfort level. A prototype workstation was then designed and constructed in which the barber sits and performs work. The workstation was tested by nine barbers in the Human Factors Laboratory in the Systems Engineering Department at King Fahd University of Petroleum and Minerals. These barbers were among those surveyed earlier in their shops. Their discomfort level was again taken and an experiment was conducted to design the shape of the footrest. The discomfort levels obtained while standing and sitting were statistically analysed. From the results, it was concluded that the mean of the discomfort levels while standing is significantly (alpha = 0.01) higher than that while sitting.

Effects of Stand and Step Training with Epidural Stimulation on Motor Function for Standing in Chronic Complete Paraplegics

PubMed Central

Rejc, Enrico; Angeli, Claudia A.; Bryant, Nicole

2017-01-01

Abstract Individuals affected by motor complete spinal cord injury are unable to stand, walk, or move their lower limbs voluntarily; this diagnosis normally implies severe limitations for functional recovery. We have recently shown that the appropriate selection of epidural stimulation parameters was critical to promoting full-body, weight-bearing standing with independent knee extension in four individuals with chronic clinically complete paralysis. In the current study, we examined the effects of stand training and subsequent step training with epidural stimulation on motor function for standing in the same four individuals. After stand training, the ability to stand improved to different extents in the four participants. Step training performed afterwards substantially impaired standing ability in three of the four individuals. Improved standing ability generally coincided with continuous electromyography (EMG) patterns with constant levels of ground reaction forces. Conversely, poorer standing ability was associated with more variable EMG patterns that alternated EMG bursts and longer periods of negligible activity in most of the muscles. Stand and step training also differentially affected the evoked potentials amplitude modulation induced by sitting-to-standing transition. Finally, stand and step training with epidural stimulation were not sufficient to improve motor function for standing without stimulation. These findings show that the spinal circuitry of motor complete paraplegics can generate motor patterns effective for standing in response to task-specific training with optimized stimulation parameters. Conversely, step training can lead to neural adaptations resulting in impaired motor function for standing. PMID:27566051

Foraging and nesting habitat of breeding male northern goshawks in the laurentian mixed forest province, Minnesota

USGS Publications Warehouse

Boal, C.W.; Andersen, D.E.; Kennedy, P.L.

2005-01-01

We used radiotelemetry to examine foraging habitat preferences of 17 breeding, male northern goshawks (Accipiter gentilis) in Minnesota from 1998-2000. We assessed habitat preference using radio relocation points and 50-m radius buffers of radio relocation points. Our data suggested that foraging male goshawks used early-successional upland conifer stands (???25 yrs old), early-successional upland deciduous stands (???50 yrs old), late-successional upland conifer stands (???50 yrs old), and late-successional upland deciduous stands (???50 yrs old) more frequently than expected based on the abundance of these vegetation types in the landscape. The 2 most available stand types, early-successional upland deciduous (<25 yrs old) and all ages of late-successional lowland conifer stands, were used less than expected by foraging goshawks. Late-successional lowland deciduous stands (???50 yrs old) were used in proportion to availability. Although analysis of relocation points suggested early-successional upland deciduous stands (25-49 yrs old) and late-successional upland conifer stands (???50 yrs old) were used in proportion to availability, analysis of buffers around relocation points indicated that these stand types were also used more than expected by foraging goshawks. Regardless of vegetation community type, stands used by goshawks were structurally similar with high canopy and understory stem densities, high canopy closure, substantial shrub cover, and large amounts of woody debris. Nest stands consisted of taller and larger diameter canopy trees and fewer understory trees than foraging stands, but stands were otherwise similar in structural features, suggesting goshawks used similar stands for nesting and foraging but that they tended to select the most mature stands for nesting. A commonality among nesting and foraging stands was the presence of open spaces between the canopy and understory foliage, and between understory and shrub layer foliage. In our study area, these spaces may have served as relatively unobstructed flight paths where foraging and nesting stands possessed stem densities at the upper end of that reported for goshawk habitat.

Take a stand on your decisions, or take a sit: posture does not affect risk preferences in an economic task.

PubMed

O'Brien, Megan K; Ahmed, Alaa A

2014-01-01

Physiological and emotional states can affect our decision-making processes, even when these states are seemingly insignificant to the decision at hand. We examined whether posture and postural threat affect decisions in a non-related economic domain. Healthy young adults made a series of choices between economic lotteries in various conditions, including changes in body posture (sitting vs. standing) and changes in elevation (ground level vs. atop a 0.8-meter-high platform). We compared three metrics between conditions to assess changes in risk-sensitivity: frequency of risky choices, and parameter fits of both utility and probability weighting parameters using cumulative prospect theory. We also measured skin conductance level to evaluate physiological response to the postural threat. Our results demonstrate that body posture does not significantly affect decision making. Secondly, despite increased skin conductance level, economic risk-sensitivity was unaffected by increased threat. Our findings indicate that economic choices are fairly robust to the physiological and emotional changes that result from posture or postural threat.

Take a stand on your decisions, or take a sit: posture does not affect risk preferences in an economic task

PubMed Central

O’Brien, Megan K.

2014-01-01

Physiological and emotional states can affect our decision-making processes, even when these states are seemingly insignificant to the decision at hand. We examined whether posture and postural threat affect decisions in a non-related economic domain. Healthy young adults made a series of choices between economic lotteries in various conditions, including changes in body posture (sitting vs. standing) and changes in elevation (ground level vs. atop a 0.8-meter-high platform). We compared three metrics between conditions to assess changes in risk-sensitivity: frequency of risky choices, and parameter fits of both utility and probability weighting parameters using cumulative prospect theory. We also measured skin conductance level to evaluate physiological response to the postural threat. Our results demonstrate that body posture does not significantly affect decision making. Secondly, despite increased skin conductance level, economic risk-sensitivity was unaffected by increased threat. Our findings indicate that economic choices are fairly robust to the physiological and emotional changes that result from posture or postural threat. PMID:25083345

Climate change induced effects on the predisposition of forests of the water protection zone Wildalpen to disturbances by bark beetles

NASA Astrophysics Data System (ADS)

Baier, P.; Pennerstorfer, J.; Schopf, A.

2012-04-01

The provision of drinking water of high quality is a precious service of forests. Large-scale disturbances like forest fires, wind throws, pest outbreaks and subsequent clear cutting may lead to changes in hydrology (runoff as well as percolation). Furthermore, water quality can be negatively influenced by increased erosion, increased decomposition of litter and humus and leaching of nitrate. Large-scale epidemics of forest pests may induce forest decline at landscape scale with subsequent long-lasting negative effects on water quality. The European spruce bark beetle, Ips typographus (L.), is one of the most significant sources of mortality in mature spruce forest ecosystems in Eurasia. The objective of this study was to apply a complex predisposition assessment system for hazard rating and for the evaluation of climate change impacts for the water protection forests of the City of Vienna in Wildalpen. The following steps have been done to adapt/apply the bark beetle phenology model and the hazard rating system: -application, adaptation and validation of the bark beetle phenology model PHENIPS concerning start of dispersion, brood initiation, duration of development, beginning of sister broods, voltinism and hibernation - spatial/temporal modelling of the phenology and voltinism of I. typographus using past, present as well as projected climate data - application and validation of the stand- and site related long-term predisposition assessment system using forest stand/site data, annual damage reports and outputs of phenology modelling as data input - mapping of endangered areas and assessment of future susceptibility to infestations by I. typographus and other disturbing agents based on climate scenarios using GIS. The assessment of site- and stand-related predisposition revealed that the forest stands in Wildalpen are highly susceptible to bark beetle infestation. More than 65% of the stands were assigned to the predisposition classes high/very high. Only 10% of the stands showed a low stand-related predisposition to bark beetle infestations. This high susceptibility to bark beetle damage is related to the dominance of even-aged, spruce-dominated mature stands. The projected change in voltinism of I. typographus will further increase total predisposition of the stands to bark beetle infestations. Mapping the projected predisposition of present-day forest stands at the end of the century clearly indicated that stands with high/very high susceptibility to bark beetle infestation form large continuous areas, a pre-requisite for extended epidemics of I. typographus.

Levels-of-growing-stock cooperative study in Douglas-fir: report no. 09—Some comparisons of DFSIM estimates with growth in the levels-of-growing-stock study.

Treesearch

Robert O. Curtis

1987-01-01

Initial stand statistics for the levels-of-growing-stock study installations were projected by the Douglas-fir stand simulation program (DFSIM) over the available periods of observation. Estimates were compared with observed volume and basal area growth, diameter change, and mortality. Overall agreement was reasonably good, although results indicate some biases and a...

Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam

NASA Astrophysics Data System (ADS)

Lu, Yuan; Katz, Joseph; Prosperetti, Andrea

2013-07-01

In this experimental study, we generate a 500 kHz high-intensity focused ultrasonic beam, with pressure amplitude in the focal zone of up to 1.9 MPa, in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line holography. Variations in the water density and refractive index are used for determining the spatial distribution of the acoustic pressure nonintrusively. Several cavitation phenomena occur within the acoustic partially standing wave caused by the reflection of sound from the walls of the test chamber. At all sound levels, bubbly layers form in the periphery of the focal zone in the pressure nodes of the partial standing wave. At high sound levels, clouds of vapor microbubbles are generated and migrate in the direction of the acoustic beam. Both the cloud size and velocity vary periodically, with the diameter peaking at the pressure nodes and velocity at the antinodes. A simple model involving linearized bubble dynamics, Bjerknes forces, sound attenuation by the cloud, added mass, and drag is used to predict the periodic velocity of the bubble cloud, as well as qualitatively explain the causes for the variations in the cloud size. The analysis shows that the primary Bjerknes force and drag dominate the cloud motion, and suggests that the secondary Bjerknes force causes the oscillations in the cloud size.

In-situ monitoring of blood glucose level for dialysis machine by AAA-battery-size ATR Fourier spectroscopy

NASA Astrophysics Data System (ADS)

Hosono, Satsuki; Sato, Shun; Ishida, Akane; Suzuki, Yo; Inohara, Daichi; Nogo, Kosuke; Abeygunawardhana, Pradeep K.; Suzuki, Satoru; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

2015-07-01

For blood glucose level measurement of dialysis machines, we proposed AAA-battery-size ATR (Attenuated total reflection) Fourier spectroscopy in middle infrared light region. The proposed one-shot Fourier spectroscopic imaging is a near-common path and spatial phase-shift interferometer with high time resolution. Because numerous number of spectral data that is 60 (= camera frame rare e.g. 60[Hz]) multiplied by pixel number could be obtained in 1[sec.], statistical-averaging improvement realize high-accurate spectral measurement. We evaluated the quantitative accuracy of our proposed method for measuring glucose concentration in near-infrared light region with liquid cells. We confirmed that absorbance at 1600[nm] had high correlations with glucose concentrations (correlation coefficient: 0.92). But to measure whole-blood, complex light phenomenon caused from red blood cells, that is scattering and multiple reflection or so, deteriorate spectral data. Thus, we also proposed the ultrasound-assisted spectroscopic imaging that traps particles at standing-wave node. Thus, if ATR prism is oscillated mechanically, anti-node area is generated around evanescent light field on prism surface. By elimination complex light phenomenon of red blood cells, glucose concentration in whole-blood will be quantify with high accuracy. In this report, we successfully trapped red blood cells in normal saline solution with ultrasonic standing wave (frequency: 2[MHz]).

Thinning results from a mixed upland hardwood stand after 35 years

Treesearch

Ronald J., Jr. Myers; Kenneth R. Roeder; W. Henry McNab

2008-01-01

A long-term study of precommercial thinning was installed in a 6-year-old oak-dominated stand regenerated by clearcutting in the southern Appalachian Mountains of North Carolina. Three levels of residual stand density were tested: control (no thinning), and 200, and 400 residual trees per acre (TPA). Objectives of the study were to determine the response of an upland...

Uneven-aged management of old-growth spruce-fir forests: Cutting methods and stand structure goals for the initial entry

Treesearch

Robert R. Alexander; Carleton B. Edminster

1977-01-01

Topics discussed include: (1) cutting methods, (2) stand structure goals, which involve choosing a residual stocking level, selecting a maximum tree size, and establishing a diameter distribution using the "q" technique, and (3) harvesting and removal of trees. Examples illustrate how to determine realistic stand structures for the initial entry for...

Growth reductions in naturally regenerated southern pine stands in Alabama and Georgia

Treesearch

G.A. Ruark; C.E. Thomas; W.A. Bechtold; D.M. May

1991-01-01

Data from Forest Inventory and analysis (FIA) units of the USDA Forest Service were used to compare average annual stand-level basal area accretion onto survivor pines in naturally regenerated pine stands throughout Alabama and Georgia. Growth rates measured between 1972-82 were compared to growth rates during the previous 10-year survey cycle in each state. Separate...

Adjustments of individual-tree survival and diameter-growth equations to match whole-stand attributes

Treesearch

Quang V. Cao

2010-01-01

Individual-tree models are flexible and can perform well in predicting tree survival and diameter growth for a certain growing period. However, the resulting stand-level outputs often suffer from accumulation of errors and subsequently cannot compete with predictions from whole-stand models, especially when the projection period lengthens. Evaluated in this study were...

Estimation of crown cover in interior ponderosa pine stands: Effects of thinning and prescribed fire

Treesearch

Nicholas Vaughn; Martin W. Ritchie

2005-01-01

We evaluated the relationship between crown cover measured with a vertical sight tube and stand basal area per acre in treated (thinned, burned, and thinned and burned) and untreated interior ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in northeastern California. Crown cover was significantly related to basal area at the plot level and...

Stocking levels and underlying assumptions for uneven-aged Ponderosa Pine stands.

Treesearch

P.H. Cochran

1992-01-01

Potential Problems With Q-Values Many ponderosa pine stands have a limited number of size classes, and it may be desirable to carry very large trees through several cutting cycles. Large numbers of trees below commercial size are not needed to provide adequate numbers of future replacement trees. Under these conditions, application of stand density index (SDI) can have...

Growth of northern hardwoods in New England: a 25-year update

Treesearch

William B. Leak; Jeffrey H. Gove

2008-01-01

Twenty-five-year results from a study of four stand density levels and three percentages of sawtimber in a beech-red maple-birch-hemlock stand in New Hampshire showed that moderate stand densities of 60- to 80-ft2/ac with 25- to 30-ft2 of sawtimber produced the best growth responses. Ingrowth was dominated by beech, red...

Fuel reduction treatments affect stand structure of hardwood forests in Western North Carolina and Southern Ohio, USA

Treesearch

Thomas A. Waldrop; Daniel A. Yaussy; Ross J. Phillips; Todd A. Hutchinson; Lucy Brudnak; Ralph E.J. Boerner

2008-01-01

Prescribed fire and mechanical treatments were tested at the two hardwood sites of the National Fire and Fire Surrogate Study (southern and central Appalachian regions) for impacts to stand structure. After two fires and one mechanical treatment, no treatment or treatment combination restored stand structure to historical levels. Burning alone had little impact on...

Heavy thinning of ponderosa pine stands: An Arizona case study

Treesearch

Peter F. Ffolliott; Jr. Baker; Gerald J. Gottfried

2000-01-01

Growth and structural changes in a mosaic of even-aged ponderosa pine (Pinus ponderosa) stands were studied for 25 years to determine the long-term impacts of a heavy thinning treatment to a basal-area level of 25 ft2/acre. Basal area and volume growth of these stands has increased since thinning and likely will continue to...

Managing mature, even-aged stands

Treesearch

Ivan L. Sander; H. Clay Smith

1989-01-01

Foresters generally consider central hardwood stands mature when they are 80 to 100 years old or have reached a specified rotation age. However, by the time stands are 50 to 60 years old and in the large pole/small sawtimber size, they have generally slowed in height growth, their annual basal area growth has leveled off, and except for size, they have many of the...

Effects of stand density on top height estimation for ponderosa pine

Treesearch

Martin Ritchie; Jianwei Zhang; Todd Hamilton

2012-01-01

Site index, estimated as a function of dominant-tree height and age, is often used as an expression of site quality. This expression is assumed to be effectively independent of stand density. Observation of dominant height at two different ponderosa pine levels-of-growing-stock studies revealed that top height stability with respect to stand density depends on the...

Development, succession, and stand dynamics of upland oak forests in the Wisconsin Driftless Area: Implications for oak regeneration and management

Treesearch

Megan L. Buchanan; Kurt F. Kipfmueller; Anthony W. D' Amato

2017-01-01

Throughout the deciduous forests of the eastern United States, oak (Quercus) regeneration has declined in stands historically dominated by oak species. In the Wisconsin Driftless Area, the level of decline in oak regeneration is variable and influenced by stand structural development, historical disturbance regime, abiotic site characteristics, and...

Growth of ponderosa pine thinned to different stocking levels in central Oregon: 30-year results.

Treesearch

P.H. Cochran; James W. Barrett

1999-01-01

Periodic annual increments (PAI) for survivor diameters decreased curvilinearly with increasing stand density. Gross volume and basal areas PAIs increased linearly with increasing stand density. Growth of basal area and volume for the 20 largest trees per acre were reduced curvilinearly with increasing stand density. Bark beetles were the primary cause of mortality. No...

[Soil quality assessment of forest stand in different plantation esosystems].

PubMed

Huang, Yu; Wang, Silong; Feng, Zongwei; Gao, Hong; Wang, Qingkui; Hu, Yalin; Yan, Shaokui

2004-12-01

After a clear-cutting of the first generation Cunninghamia lanceolata plantation in 1982, three plantation ecosystems, pure Michelia macclurei stand (PMS), pure Chinese-fir stand (PCS) and their mixed stand, were established in spring 1983, and their effects on soil characteristics were evaluated by measuring some soil physical, chemical, microbiological and biochemical parameters. After 20 years' plantation, all test indices showed differences among different forest management models. Both PMS and MCM had a favorable effect on soil fertility maintenance. Soil quality assessment showed that some soil functions, e.g., water availability, nutrient availability, root suitability and soil quality index were all in a moderate level under the mixed and pure PMS stands, whereas in a relatively lower level under successive PCS stand. The results also showed that there existed close correlations between soil total organic C (TOC), cation exchange capacity (CEC), microbial biomass-C (Cmic) and other soil physical, chemical and biological indices. Therefore, TOC, CEC and Cmic could be used as the indicators in assessing soil quality in this study area. In addition, there were also positive correlations between soil microbial biomass-C and TOC, soil microbial biomass-N and total N, and soil microbial biomass-P and total P in the present study.

Productivity of a mature Douglas-fir stand.

Treesearch

Carl M. Berntsen

1960-01-01

Records from a mature Douglas-fir stand on the Mount Hood National Forest in northwestern Oregon indicate that very high rates of gross growth are maintained up to ages as high as 250 years. Where such stands are held in reserve for future clear cutting, forest managers have an opportunity to recapture a large share of this gross production by salvaging mortality at...

Object-oriented classification of forest structure from light detection and ranging data for stand mapping

Treesearch

Alicia A. Sullivan; Robert J. McGaughey; Hans-Erik Andersen; Peter Schiess

2009-01-01

Stand delineation is an important step in the process of establishing a forest inventory and provides the spatial framework for many forest management decisions. Many methods for extracting forest structure characteristics for stand delineation and other purposes have been researched in the past, primarily focusing on high-resolution imagery and satellite data. High-...

Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition.

PubMed

Clarke, Sarah B; Deighton, Kevin; Newman, Caroline; Nicholson, Gareth; Gallagher, Liam; Boos, Christopher J; Mellor, Adrian; Woods, David R; O'Hara, John P

2018-01-01

Postural control and joint position sense are essential for safely undertaking leisure and professional activities, particularly at high altitude. We tested whether exposure to a 12-day trek with a gradual ascent to high altitude impairs postural control and joint position sense. This was a repeated measures observational study of 12 military service personnel (28±4 years). Postural control (sway velocity measured by a portable force platform) during standing balance, a Sharpened Romberg Test and knee joint position sense were measured, in England (113m elevation) and at 3 research camps (3619m, 4600m and 5140m) on a 12-day high altitude trek in the Dhaulagiri region of Nepal. Pulse oximetry, and Lake Louise scores were also recorded on the morning and evening of each trek day. Data were compared between altitudes and relationships between pulse oximetry, Lake Louise score, and sway velocity were explored. Total sway velocity during standing balance with eyes open (p = 0.003, d = 1.9) and during Sharpened Romberg test with eyes open (p = 0.007, d = 1.6) was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Anterior-posterior sway velocity during standing balance with eyes open was also significantly greater at altitudes of 3619m and 5140m when compared with sea level (p = 0.001, d = 1.9). Knee joint position sense was not altered at higher altitudes. There were no significant correlations between Lake Louise scores, pulse oximetry and postural sway. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control without impairment in knee joint position sense. Importantly, these impairments did not worsen at higher altitudes of 4600 m or 5140 m. The present findings should be considered during future trekking expeditions when developing training strategies targeted to manage impairments in postural control that occur with increasing altitude.

Energy expended and knee joint load accumulated when walking, running, or standing for the same amount of time.

PubMed

Miller, Ross H; Edwards, W Brent; Deluzio, Kevin J

2015-01-01

Evidence suggests prolonged bouts of sitting are unhealthy, and some public health messages have recently recommended replacing sitting with more standing. However, the relative benefits of replacing sitting with standing compared to locomotion are not known. Specifically, the biomechanical consequences of standing compared to other sitting-alternatives like walking and running are not well known and are usually not considered in studies on sitting. We compared the total knee joint load accumulated (TKJLA) and the total energy expended (TEE) when performing either walking, running, or standing for a common exercise bout duration (30 min). Walking and running both (unsurprisingly) had much more TEE than standing (+300% and +1100%, respectively). TKJLA was similar between walking and standing and 74% greater in running. The results suggest that standing is a poor replacement for walking and running if one wishes to increases energy expenditure, and may be particularly questionable for use in individuals at-risk for knee osteoarthritis due to its surprisingly high TKJLA (just as high as walking, 56% of the load in running) and the type of loading (continuous compression) it places on cartilage. However, standing has health benefits as an "inactivity interrupter" that extend beyond its direct energy expenditure. We suggest that future studies on standing as an inactivity intervention consider the potential biomechanical consequences of standing more often throughout the day, particularly in the case of prolonged bouts of standing. Copyright © 2014 Elsevier B.V. All rights reserved.

Water use of a multigenotype poplar short-rotation coppice from tree to stand scale.

PubMed

Bloemen, Jasper; Fichot, Régis; Horemans, Joanna A; Broeckx, Laura S; Verlinden, Melanie S; Zenone, Terenzio; Ceulemans, Reinhart

2017-02-01

Short-rotation coppice (SRC) has great potential for supplying biomass-based heat and energy, but little is known about SRC's ecological footprint, particularly its impact on the water cycle. To this end, we quantified the water use of a commercial scale poplar ( Populus ) SRC plantation in East Flanders (Belgium) at tree and stand level, focusing primarily on the transpiration component. First, we used the AquaCrop model and eddy covariance flux data to analyse the different components of the stand-level water balance for one entire growing season. Transpiration represented 59% of evapotranspiration (ET) at stand scale over the whole year. Measured ET and modelled ET were lower as compared to the ET of reference grassland, suggesting that the SRC only used a limited amount of water. Secondly, we compared leaf area scaled and sapwood area scaled sap flow ( F s ) measurements on individual plants vs. stand scale eddy covariance flux data during a 39-day intensive field campaign in late summer 2011. Daily stem diameter variation (∆ D ) was monitored simultaneously with F s to understand water use strategies for three poplar genotypes. Canopy transpiration based on sapwood area or leaf area scaling was 43.5 and 50.3 mm, respectively, and accounted for 74%, respectively, 86%, of total ecosystem ET measured during the intensive field campaign. Besides differences in growth, the significant intergenotypic differences in daily ∆ D (due to stem shrinkage and swelling) suggested different water use strategies among the three genotypes which were confirmed by the sap flow measurements. Future studies on the prediction of SRC water use, or efforts to enhance the biomass yield of SRC genotypes, should consider intergenotypic differences in transpiration water losses at tree level as well as the SRC water balance at stand level.

Different antihypertensive effect of beta-blocking drugs in low and normal-high renin hypertension.

PubMed

Kralberg, B E; Tolagen, K

1976-05-31

The treatment response to beta-adrenoceptor blocking drugs was compared in two groups of patients with primary (essential) hypertension and different renin levels. Each group consisted of 25 patients and was equally distributed regarding age, severity and stage of hypertension. In the first group (group 1), the mean upright plasma renin activity was 0.8 ng ml-1h-1 (range 0.3 to 1.5) and the patients were considered to have low renin hypertension. In the other group (group 2) the patients had a mean plasma renin activity of 2.1 ng ml-1h-1 (range 1.1 to 5.1) and were considered to have normal to high renin hypertension. In both groups the patients were initially treated with beta-blocking drugs; in group 1 with a beta-blocker corresponding to an average dose of 311 mg propranolol a day for at least eight weeks and in group 2 with propranolol 320 mg a day in a fixed dose for eight weeks. The hypotensive response differed significantly between the two groups (p less than 0.001). In group 1 the pretreatment blood pressure was 197/117 mm Hg supine and 198/120 mm Hg standing. During treatment blood pressure decreased only 5/3 mm Hg supine and 9/5 mm Hg standing. The pretreatment blood pressure in group 2 was 187/114 mm Hg supine and 186/117 mm Hg standing. Beta-blocking therapy reduced blood pressure 36/23 and 34/18 mm Hg, respectively (both p less than 0.001). Pulse rates fell significantly in the two groups, both in the lying and standing positions. In 17 patients with low renin hypertension (group 1), a volume-depleting drug was added (spironolactone, 14 patients; thiazides, 3 patients) and this achieved a marked fall in blood pressure levels of 38/16 mm Hg supine and 37/19 mm Hg standing (both p less than 0.001). These results suggest the following: (1) Most patients with normal to high plasma renin activity respond well to moderate doses of propranolol. (2) Propranolol given in the same doses is almost without antihypertensive effect in patients with low renin hypertension. (3) A volume factor may be operating in patients with low renin hypertension since a hypotensive effect is demonstrated after the addition of volume-depleting drugs. (4) Determination of plasma renin activity with adequate methods can predict the treatment response to hypotensive agents.

High Voltage Test-Stand Research Done on ICRF Antenna Elements of the High-Harmonic Fast-Wave System of NSTX

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

Perkins, R. J.; Ahn, J.W.; Bortolon, A.

The twelve-strap high-harmonic fast-wave (HHFW) antenna on NSTX has exhibited a high-voltage standoff around 25 kV during previous experimental campaigns; this standoff needs to be improved for increased power coupling. During the recent NSTX-U upgrade period, a test-stand was set up with two antenna straps along with Faraday screens for testing purposes. Using a diagnostic suite consisting of a fast camera, a residual gas analyzer, a pressure gage, high-voltage probes, and an infrared camera, several interesting discoveries were made, leading to possible improvements of the antenna RF voltage operation level. First, arcing was observed outside the Faraday shields towards themore » low-voltage ("grounded") end of the straps (faraday shield box ends); this arcing was successfully eliminated by installing an additional grounding point between the Faraday shield box and the vessel wall. Second, considerable outgassing was observed during the RF pulse and the amount of outgassing was found to decrease with increasing RF power, possibly indicative of multipacting. Finally, infrared camera measurements of heating on the Faraday shield assembly suggest that the return currents on the Faraday shield box are highly localized at the box sides and possibly account for the pressure increase observed. Computations of these RF currents using Microwave Studio show qualitative agreement with the heated regions. New grounding points between the antenna box and the vessel have been implemented in NSTX-U, where future tests will be done to determine if the high-voltage standoff has improved. Further antenna improvements will be sought through future experiments on the test stand.« less

In Maine, Postsecondary Success Starts before College

ERIC Educational Resources Information Center

LePage, Paul R.

2011-01-01

A 2008 report from the Joint Standing Committee on Education and Culture Affairs of the Maine Legislature indicates a quarter of those who enrolled at a public university in Maine required a remedial course to catch them up to the level where they should have been when they completed high school. Regardless of how hard Maine has tried and how much…

Influence of nutrition and stress on sugar maple at a regional scale

Treesearch

Richard A. Hallett; Scott W. Bailey; Stephen B. Horsley; Robert P. Long

2006-01-01

Sugar maple (Acer saccharum Marsh.) decline disease on the Allegheny Plateau (region 1) resulted in high levels of mortality during the 1990s. Sugar maple was predisposed to decline because of an imbalance in Mg, Ca, and Mn nutrition and incited to decline by repeated defoliation. We sampled 33 stands in New York, Vermont, and New Hampshire (region 2...

Brown-spot resistance in natural stands of longleaf pine seedlings

Treesearch

William D. Boyer

1972-01-01

An average of 10 percent of longleaf pine (Pinus palustris Mill.) seedlings in several natural populations remained nearly free of brown-spot needle blight (Scirrhia acicola (Dearn.) Siggers) year after year, despite high injection levels in the population as a whole. In one study, these individuals averaged 8 feet taller at age 24 than surviving trees that were less...

Rapid measurement of the three-dimensional distribution of leaf orientation and the leaf angle probability density function using terrestrial LiDAR scanning

USDA-ARS?s Scientific Manuscript database

Leaf orientation plays a fundamental role in many transport processes in plant canopies. At the plant or stand level, leaf orientation is often highly anisotropic and heterogeneous, yet most analyses neglect such complexity. In many cases, this is due to the difficulty in measuring the spatial varia...

Effects of a recreational ice skating program on the functional mobility of a child with cerebral palsy.

PubMed

Walsh, Sharon Fleming; Scharf, Michael G

2014-04-01

The purpose of this study was to describe the effects of an ice skating program on the ambulation, strength, posture and balance of a child with cerebral palsy (CP). The subject was a five-year-old female with a diagnosis of CP and a Gross Motor Classification System level of III. The subject was a slow and labored household ambulator on level surfaces with bilateral forearm crutches and bilateral ankle foot orthoses. She was unable to transfer to and from the floor to stand independently, stand unsupported or take steps independently. Until the initiation of this study she was receiving physical therapy services 2×/week. For the purpose of this study she participated in a 1 h/week local ice skating program for people with disabilities for a period of four months. The subject displayed clinically significant improvements in functional mobility including: improved standing posture; independent transfer to and from the floor to stand; maintenance of independent standing for 3 min; independent walking for 10 feet; increased ability to isolate extremity musculature; increased strength; improved Gross Motor Function Measure-88 scores and increased endurance. A subsequent testing session four months after the ice skating program had ended displayed declines but not to pre-intervention levels in muscle strength; ability to transfer to and from the floor to stand; functional mobility and standing balance. The results appear to suggest that the participation in an ice skating program clinically improved this child's functional mobility. Further research needs to be done with regard to physical recreational programs and the benefit they can have on the function of children with activity limitations.

Around Marshall

NASA Image and Video Library

1963-05-07

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photograph, taken from ground level on May 7, 1963, gives a close look at one of the four towers legs of the S-IC test stand nearing its completed height.

Comparing joint kinematics and center of mass acceleration as feedback for control of standing balance by functional neuromuscular stimulation.

PubMed

Nataraj, Raviraj; Audu, Musa L; Triolo, Ronald J

2012-05-06

The purpose of this study was to determine the comparative effectiveness of feedback control systems for maintaining standing balance based on joint kinematics or total body center of mass (COM) acceleration, and assess their clinical practicality for standing neuroprostheses after spinal cord injury (SCI). In simulation, controller performance was measured according to the upper extremity effort required to stabilize a three-dimensional model of bipedal standing against a variety of postural disturbances. Three cases were investigated: proportional-derivative control based on joint kinematics alone, COM acceleration feedback alone, and combined joint kinematics and COM acceleration feedback. Additionally, pilot data was collected during external perturbations of an individual with SCI standing with functional neuromuscular stimulation (FNS), and the resulting joint kinematics and COM acceleration data was analyzed. Compared to the baseline case of maximal constant muscle excitations, the three control systems reduced the mean upper extremity loading by 51%, 43% and 56%, respectively against external force-pulse perturbations. Controller robustness was defined as the degradation in performance with increasing levels of input errors expected with clinical deployment of sensor-based feedback. At error levels typical for body-mounted inertial sensors, performance degradation due to sensor noise and placement were negligible. However, at typical tracking error levels, performance could degrade as much as 86% for joint kinematics feedback and 35% for COM acceleration feedback. Pilot data indicated that COM acceleration could be estimated with a few well-placed sensors and efficiently captures information related to movement synergies observed during perturbed bipedal standing following SCI. Overall, COM acceleration feedback may be a more feasible solution for control of standing with FNS given its superior robustness and small number of inputs required.

Comparing joint kinematics and center of mass acceleration as feedback for control of standing balance by functional neuromuscular stimulation

PubMed Central

2012-01-01

Background The purpose of this study was to determine the comparative effectiveness of feedback control systems for maintaining standing balance based on joint kinematics or total body center of mass (COM) acceleration, and assess their clinical practicality for standing neuroprostheses after spinal cord injury (SCI). Methods In simulation, controller performance was measured according to the upper extremity effort required to stabilize a three-dimensional model of bipedal standing against a variety of postural disturbances. Three cases were investigated: proportional-derivative control based on joint kinematics alone, COM acceleration feedback alone, and combined joint kinematics and COM acceleration feedback. Additionally, pilot data was collected during external perturbations of an individual with SCI standing with functional neuromuscular stimulation (FNS), and the resulting joint kinematics and COM acceleration data was analyzed. Results Compared to the baseline case of maximal constant muscle excitations, the three control systems reduced the mean upper extremity loading by 51%, 43% and 56%, respectively against external force-pulse perturbations. Controller robustness was defined as the degradation in performance with increasing levels of input errors expected with clinical deployment of sensor-based feedback. At error levels typical for body-mounted inertial sensors, performance degradation due to sensor noise and placement were negligible. However, at typical tracking error levels, performance could degrade as much as 86% for joint kinematics feedback and 35% for COM acceleration feedback. Pilot data indicated that COM acceleration could be estimated with a few well-placed sensors and efficiently captures information related to movement synergies observed during perturbed bipedal standing following SCI. Conclusions Overall, COM acceleration feedback may be a more feasible solution for control of standing with FNS given its superior robustness and small number of inputs required. PMID:22559852

BVOC emission in Norway spruce: the effect of stand structure, high temperature and ozone levels.

NASA Astrophysics Data System (ADS)

Pallozzi, Emanuele; Guidolotti, Gabriele; Večeřová, Kristýna; Esposito, Raffaela; Lusini, Ilaria; Juráň, Stanislav; Urban, Otmar; Calfapietra, Carlo

2015-04-01

Norway spruce (Picea abies L.) is a widely distributed conifer species in the boreal zone and mountain areas of central Europe and is a moderate emitter of volatile organic compounds (BVOC). Although the vaporization and diffusion processes from resin ducts were generally considered to be the main processes for monoterpene emissions in conifers, recently it has been showed that a significant portion (up to one third) of monoterpene emissions of Norway spruce can originate from novel biosynthesis, thus depending on photosynthetic processes. For this reason, both biosynthesis and emission are strongly influenced by the environment and the stand structure. They increase with both increasing light and temperature during the warmer periods, although those are the periods with the higher ozone concentration that usually act as an inhibitor of both assimilation and isoprenoids synthesis and emission. On the other hand, stand structure can play an important role, because the photosynthetic capacity is influenced by temperature and light conditions through the canopy. In order to assess the effects of stand structure, temperature and ozone on isoprenoids emission of Norway spruce we carried out field and laboratory experiments. In the experimental field campaigns we measured: assimilation and BVOC emission from needles of sun and shade layers within the canopy of the spruce forest present at the Bily Kriz experimental research site (Moravian-Silesian Beskydy Mountains, 49° 33' N, 18° 32' E, NE of Czech Republic, 908 m a.s.l.). Moreover in the same layers we measured continuously concentration of BVOCs in the air using a PTR-TOF-MS. In laboratory we analyzed the effects of short-term exposure to high temperature and high ozone concentrations on branches of spruce trees collected at the Bily Kriz experimental research site. Preliminary results show that in Norway spruce both stand structure and environmental conditions influenced the gas exchange and BVOC emission rates. The exposure to high temperature and the position of the needles at the sun layer positively affect the BVOC emission, while the short-term exposure to high ozone concentration did not significantly affect BVOC emissions. The study contributes to increase our understanding about the environmental and structural controls of BVOC emission in response to both tropospheric ozone and global changes.

Modeling tree-level fuel connectivity to evaluate the effectiveness of thinning treatments for reducing crown fire potential

Treesearch

Marco A. Contreras; Russell A. Parsons; Woodam Chung

2012-01-01

Land managers have been using fire behavior and simulation models to assist in several fire management tasks. These widely-used models use average attributes to make stand-level predictions without considering spatial variability of fuels within a stand. Consequently, as the existing models have limitations in adequately modeling crown fire initiation and propagation,...

Stand-level growth and yield component models for red oak-sweetgum forests on Mid-South minor stream bottoms

Treesearch

Emily B. Schultz; J. Clint Iles; Thomas G. Matney; Andrew W. Ezell; James S. Meadows; Theodor D. Leininger; al. et.

2010-01-01

Greater emphasis is being placed on Southern bottomland hardwood management, but relatively few growth and yield prediction systems exist that are based on sufficient measurements. We present the aggregate stand-level expected yield and structural component equations for a red oak (Quercus section Lobatae)-sweetgum (Liquidambar styraciflua L.) growth and yield model....

Morphological acclimation and growth of ash (Fraxinus pennsylvanica Marsh.) advance regeneration following overstory harvesting in a Mississippi River floodplain forest

Treesearch

Alexander Sinz; Emmile S. Gardiner; Brian R. Lockhart; Ray A. Souter

2011-01-01

Stand-level growth responses and plant-level patterns of biomass accumulation and distribution were examined to learn how stand structure influences morphological acclimation and growth of green ash (Fraxinus pennsylvanica Marsh.) advance regeneration following overstory harvesting. Nine, 20-ha plots that received clearcut harvesting (100% basal area removal), partial...

Distribution of standing-wave errors in real-ear sound-level measurements.

PubMed

Richmond, Susan A; Kopun, Judy G; Neely, Stephen T; Tan, Hongyang; Gorga, Michael P

2011-05-01

Standing waves can cause measurement errors when sound-pressure level (SPL) measurements are performed in a closed ear canal, e.g., during probe-microphone system calibration for distortion-product otoacoustic emission (DPOAE) testing. Alternative calibration methods, such as forward-pressure level (FPL), minimize the influence of standing waves by calculating the forward-going sound waves separate from the reflections that cause errors. Previous research compared test performance (Burke et al., 2010) and threshold prediction (Rogers et al., 2010) using SPL and multiple FPL calibration conditions, and surprisingly found no significant improvements when using FPL relative to SPL, except at 8 kHz. The present study examined the calibration data collected by Burke et al. and Rogers et al. from 155 human subjects in order to describe the frequency location and magnitude of standing-wave pressure minima to see if these errors might explain trends in test performance. Results indicate that while individual results varied widely, pressure variability was larger around 4 kHz and smaller at 8 kHz, consistent with the dimensions of the adult ear canal. The present data suggest that standing-wave errors are not responsible for the historically poor (8 kHz) or good (4 kHz) performance of DPOAE measures at specific test frequencies.

Tree grades, yields and values for some Appalachian hardwoods

Treesearch

Robert A. Campbell

1951-01-01

Foresters ahve long recognized the need for a better method of appraising standing timber in terms of quality as well as volume of lumber that trees may be expected to produce. Because the range in price between high-grade lumber and low-grade lumber is extremely wide, a stand of high-quality timber is much more valuable than a low-quality stand. In spite of this,...

Response of sapling stands to cultural treatments

Treesearch

H. Clay Smith

1989-01-01

The main reasons for precommercial cultural practices in sapling stands (trees less than 5 inches d.b.h.) are to increase growth of residual trees, increase stand value, and improve or maintain species composition. On good sites (northern red oak site index 70 and above), treating sapling stands may be justified by increased diameter growth of high value species. On...

First order sea-level cycles and supercontinent break up

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

Heller, P.L.; Angevine, C.L.

1985-01-01

The authors have developed a model that successfully predicts the approximate magnitude and timing of long term sea-level change without relying on short term increases in global spreading rates. The model involves the following key assumptions. (1) Ocean basins have two types of area/age distributions; Pacific ocean basins are rimmed by subduction zones and have triangular distributions; and Atlantic ocean basins which open at constant rates, have no subduction, and so have rectangular distributions. (2) The total area of the global ocean is constant so that the Pacific basin must close as the Atlantic opens. These assumptions approximate modern globalmore » ocean basin conditions. The model begins with supercontinent break up. As the Atlantic begins to open, the mean age of the global ocean decreases, the mean depth of the sea floor shallows, and sea level, therefore, rises. Once the Atlantic occupies more than 8 to 10% of the global ocean area, the mean age and depth of the ocean floor increases resulting in a sea-level fall. The model can be applied to the mid-Cretaceous sea-level high stand which followed break up of Pangea by 80 to 100 Ma. Based on average Atlantic opening rates, sea level rises to a peak of 44 m at 80 Ma after opening began and then falls by 84 m to the present. Thus the model is capable of explaining approximately half of the total magnitude of the post-mid-Cretaceous eustatic fall without invoking short-term changes in global spreading rates. In addition, the model predicts the observed time lag between supercontinent break up and sea-level high stand for both Mesozoic as well as early Paleozoic time.« less

Estimating tree grades for Southern Appalachian natural forest stands

Treesearch

Jeffrey P. Prestemon

1998-01-01

Log prices can vary significantly by grade: grade 1 logs are often several times the price per unit of grade 3 logs. Because tree grading rules derive from log grading rules, a model that predicts tree grades based on tree and stand-level variables might be useful for predicting stand values. The model could then assist in the modeling of timber supply and in economic...

Quantifying structural and physiological controls on variation in canopy transpiration among planted pine and hardwood species in the southern Appalachians

Treesearch

Chelcy R. Ford; Robert M. Hubbard; James M. Vose

2010-01-01

Recent studies have shown that planted pine stands exhibit higher evapotranspiration (ET) and are more sensitive to climatic conditions compared with hardwood stands. Whether this is due to management and stand effects, biological effects or their interaction is poorly understood. We estimated growing season canopy- and sap flux-scaled leaf-level transpiration (Ec and...

Shortleaf pine reproduction abundance and growth in pine-oak stands in the Missouri Ozarks

Treesearch

Elizabeth M. Blizzard; Doyle Henken; John M. Kabrick; Daniel C. Dey; David R. Larsen; David Gwaze

2007-01-01

We conducted an operational study to evaluate effect of site preparation treatments on pine reproduction density and the impact of overstory basal area and understory density on pine reproduction height and basal diameter in pine-oak stands in the Missouri Ozarks. Stands were harvested to or below B-level stocking, but patchiness of the oak decline lead to some plots...

Effects of repeated precommercial thinnings in central hardwood sapling stands

Treesearch

Donald E. Hilt; Martin E. Dale

1982-01-01

Precommercial thinnings were repeated four times in a central hardwood sapling stand beginning at age 8 and ending at age 22. Treated plots were thinned on an area-wide basis to specified density levels of 30-, 50-, and 70-percent stocking. The species composition of all stems in the stand was altered somewhat by thinning, but similar trends occurred on control plots....

Snag densities in old-growth stands on the Gasquet Ranger District, Six Rivers National Forest, California

Treesearch

Thomas M. Jimerson

1989-01-01

Baseline levels for densities of snags (standing dead trees) wered etermined in undisturbed old-growth stands on the Gasquet Ranger District. Six Riven National Forest, California. Snag species, number, diameter at breast height (d.b.h.), height, cavity type, cavity use, decay class, and snag origin were recorded on 317 plots over a 2-year period. The 2121 snags...

Stump sprout dynamics in response to reductions in stand density for nine upland hardwood species in the southern Appalachian Mountains

Treesearch

Tara L. Keyser; Stanley J. Zarnoch

2014-01-01

Much about stump sprout dynamics of upland hardwood trees species has been obtained in clearcuts. Information on the response of stump sprouts to alternative silvicultural treatments, including treatments that manipulate stand density and stand structure is lacking. In this study we examined the influence of harvest season and levels of basal area reduction on the...

Simulated cavity tree dynamics under alternative timber harvest regimes

Treesearch

Zhaofei Fan; Stephen R Shifley; Frank R Thompson; David R Larsen

2004-01-01

We modeled cavity tree abundance on a landscape as a function of forest stand age classes and as a function of aggregate stand size classes.We explored the impact of five timber harvest regimes on cavity tree abundance on a 3261 ha landscape in southeast Missouri, USA, by linking the stand level cavity tree distribution model to the landscape age structure simulated by...

Influence of Land Cover Heterogeneity, Land-Use Change and Management on the Regional Carbon Cycle in the Upper Midwest USA as Evaluated by High-Density Observations and a Dynamic Ecosystem Model

NASA Astrophysics Data System (ADS)

Desai, A. R.; Bolstad, P. V.; Moorcroft, P. R.; Davis, K. J.

2005-12-01

The interplay between land use change, forest management and land cover variability complicates the ability to characterize regional scale (10-1000 km) exchange of carbon dioxide between the land surface and atmosphere in heterogeneous landscapes. An attempt was made to observe and model these factors and their influence on the regional carbon cycle across the upper Midwest USA. A high density of eddy-covariance carbon flux, micrometeorology, carbon dioxide mixing ratio, stand-scale biometry and canopy component flux observations have been occurring in this area as part of the Chequamegon Ecosystem-Atmosphere Study. Observations limited to sampling only dominant stands and coarse-resolution biogeochemical models limited to biome-scale parameterization neither accurately capture the variability of carbon fluxes measured by the network of eddy covariance towers nor match the regional-scale carbon flux inferred from very tall tower eddy covariance measurements and multi-site upscaling. Analysis of plot level biometric data, U.S. Forest Service Forest Inventory Analysis data and high-resolution land cover data around the tall tower revealed significant variations in vegetation type, stand age, canopy stocking and structure. Wetlands, clearcuts and recent natural disturbances occur in characteristic small non-uniformly distributed patches that aggregate to form more than 30% of the landscape. The Ecosystem Demography model, a dynamic ecosystem model that incorporates vegetation heterogeneity, canopy structure, stand age, disturbance, land use change and forest management, was parameterized with regional biometric data and meteorology, historical records of land management and high-resolution satellite land cover maps. The model will be used to examine the significance of past land use change, natural disturbance history and current forest management in explaining landscape structure and regional carbon fluxes observed in the region today.

One and two level posterior lumbar interbody fusion (PLIF) using an expandable, stand-alone, interbody fusion device: a VariLift® case series

PubMed Central

Barrett-Tuck, Rebecca; Del Monaco, Diana

2017-01-01

Background Surgical interventions such as posterior lumbar interbody fusion (PLIF) with and without posterior instrumentation are often employed in patients with degenerative spinal conditions that fail to respond to conservative medical management. The VariLift® Interbody Fusion System was developed as a stand-alone solution to provide the benefits of an intervertebral fusion device without the requirement of supplemental pedicle screw fixation. Methods In this retrospective case series, 25 patients underwent PLIF with a stand-alone VariLift® expandable interbody fusion device without adjunctive pedicle screw fixation. There were 12 men and 13 women, with a mean age of 57.2 years (range, 33–83 years); single level in 18 patients, 2 levels in 7 patients. Back pain severity was reported as none, mild, moderate, severe and worst imaginable at baseline, 6 and 12 months. Preoperatively, 88% (22 of 25) of patients reported severe back pain. Results All patients experienced symptomatic improvement and, by 12 months postoperatively, 71% (15 of 21) of patients reported only mild residual pain. Overall, pain scores improved significantly from baseline to 12 months (P=0.0002). There were no revision surgeries and fusion was achieved 12 of 13 patients (92%) who returned for a 12-month radiographic follow-up. There were three cases of intractable postsurgical pain which required extended hospitalization or pain management, one wound infection and one case of surgical site dehiscence, both treated and resolved during inpatient hospitalization. Conclusions In this single-physician case series, the VariLift® device used in single or two-level PLIF provided effective symptom relief and produced a high fusion rate without the need for supplemental fixation. PMID:28435912

One and two level posterior lumbar interbody fusion (PLIF) using an expandable, stand-alone, interbody fusion device: a VariLift® case series.

PubMed

Barrett-Tuck, Rebecca; Del Monaco, Diana; Block, Jon E

2017-03-01

Surgical interventions such as posterior lumbar interbody fusion (PLIF) with and without posterior instrumentation are often employed in patients with degenerative spinal conditions that fail to respond to conservative medical management. The VariLift ® Interbody Fusion System was developed as a stand-alone solution to provide the benefits of an intervertebral fusion device without the requirement of supplemental pedicle screw fixation. In this retrospective case series, 25 patients underwent PLIF with a stand-alone VariLift ® expandable interbody fusion device without adjunctive pedicle screw fixation. There were 12 men and 13 women, with a mean age of 57.2 years (range, 33-83 years); single level in 18 patients, 2 levels in 7 patients. Back pain severity was reported as none, mild, moderate, severe and worst imaginable at baseline, 6 and 12 months. Preoperatively, 88% (22 of 25) of patients reported severe back pain. All patients experienced symptomatic improvement and, by 12 months postoperatively, 71% (15 of 21) of patients reported only mild residual pain. Overall, pain scores improved significantly from baseline to 12 months (P=0.0002). There were no revision surgeries and fusion was achieved 12 of 13 patients (92%) who returned for a 12-month radiographic follow-up. There were three cases of intractable postsurgical pain which required extended hospitalization or pain management, one wound infection and one case of surgical site dehiscence, both treated and resolved during inpatient hospitalization. In this single-physician case series, the VariLift ® device used in single or two-level PLIF provided effective symptom relief and produced a high fusion rate without the need for supplemental fixation.

Stand-alone anchored cage versus cage with plating for single-level anterior cervical discectomy and fusion: a prospective, randomized, controlled study with a 2-year follow-up.

PubMed

Nemoto, Osamu; Kitada, Akira; Naitou, Satoko; Tachibana, Atsuko; Ito, Yuya; Fujikawa, Akira

2015-07-01

To avoid complications associated with plating in anterior cervical discectomy and fusion (ACDF), stand-alone anchored PEEK cage was developed and favourable outcomes with a low rate of dysphasia have been described. The objective of this study was to compare the clinical and radiological outcomes of ACDF using a standalone anchored PEEK cage (PREVAIL; Medtronic Sofamor Danek, Memphis, TN) with those of a PEEK cage with plating in a prospective randomized manner. Fifty patients with single-level cervical radiculopathy were randomly assigned to a PREVAIL or a PEEK cage with plating. Following 3, 6, 12, and 24 months, clinical and radiological outcomes were assessed. The mean surgical time for the patients with a PREVAIL was significantly shorter than that for those with a PEEK cage with plating. The clinical outcomes evaluated by visual analogue scale for pain and the Odom's criteria were comparable between both the groups. Both the groups demonstrated the high fusion rate (92% in PREVAIL; 96% in PEEK cage with plating). The subsidence rate and the improvement of cervical alignment were comparable between both the groups. The incidence of adjacent-level ossification was significantly lower for patients with a PREVAIL than that for those with a PEEK cage with plating. The rate of dysphasia graded by the method of Bazaz and measurement of prevertebral soft tissue swelling indicated no significant differences between both the groups. Our prospective randomized study confirmed that stand-alone anchored PEEK cage is a valid alternative to plating in ACDF with a low rate of adjacent-level ossification. However, the potential to reduce the incidence of dysphasia was not confirmed.

Around Marshall

NASA Image and Video Library

1962-07-03

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of July 3, 1963. All four of its tower legs are well underway.

Around Marshall

NASA Image and Video Library

1963-09-05

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of September 5, 1963.

n/a

NASA Image and Video Library

1962-10-26

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were built during this time. Built to the north of the massive S-IC test stand, was the F-1 Engine test stand. The F-1 test stand, a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken October 26, 1962, depicts the excavation process of the single engine F-1 stand.

Around Marshall

NASA Image and Video Library

1963-09-30

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of September 30, 1963.

Around Marshall

NASA Image and Video Library

1963-06-24

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of June 24, 1963. Two if its four tower legs are underway.

n/a

NASA Image and Video Library

1962-11-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were built during this time. Built to the north of the massive S-IC test stand, was the F-1 Engine test stand. The F-1 test stand, a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken November 15, 1962, depicts the excavation process of the single engine F-1 stand site.

Around Marshall

NASA Image and Video Library

1963-10-22

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Northeast of the massive S-IC test stand, the F-1 Engine test stand was built. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the fuel tanks that housed kerosene and just beyond those is the F-1 test stand.

Estimating Mixed Broadleaves Forest Stand Volume Using Dsm Extracted from Digital Aerial Images

NASA Astrophysics Data System (ADS)

Sohrabi, H.

2012-07-01

In mixed old growth broadleaves of Hyrcanian forests, it is difficult to estimate stand volume at plot level by remotely sensed data while LiDar data is absent. In this paper, a new approach has been proposed and tested for estimating stand forest volume. The approach is based on this idea that forest volume can be estimated by variation of trees height at plots. In the other word, the more the height variation in plot, the more the stand volume would be expected. For testing this idea, 120 circular 0.1 ha sample plots with systematic random design has been collected in Tonekaon forest located in Hyrcanian zone. Digital surface model (DSM) measure the height values of the first surface on the ground including terrain features, trees, building etc, which provides a topographic model of the earth's surface. The DSMs have been extracted automatically from aerial UltraCamD images so that ground pixel size for extracted DSM varied from 1 to 10 m size by 1m span. DSMs were checked manually for probable errors. Corresponded to ground samples, standard deviation and range of DSM pixels have been calculated. For modeling, non-linear regression method was used. The results showed that standard deviation of plot pixels with 5 m resolution was the most appropriate data for modeling. Relative bias and RMSE of estimation was 5.8 and 49.8 percent, respectively. Comparing to other approaches for estimating stand volume based on passive remote sensing data in mixed broadleaves forests, these results are more encouraging. One big problem in this method occurs when trees canopy cover is totally closed. In this situation, the standard deviation of height is low while stand volume is high. In future studies, applying forest stratification could be studied.

Reconfigurable, Bi-Directional Flexfet Level Shifter for Low-Power, Rad-Hard Integration

NASA Technical Reports Server (NTRS)

DeGregorio, Kelly; Wilson, Dale G.

2009-01-01

Two prototype Reconfigurable, Bi-directional Flexfet Level Shifters (ReBiLS) have been developed, where one version is a stand-alone component designed to interface between external low voltage and high voltage, and the other version is an embedded integrated circuit (IC) for interface between internal low-voltage logic and external high-voltage components. Targeting stand-alone and embedded circuits separately allows optimization for these distinct applications. Both ReBiLS designs use the commercially available 180-nm Flex fet Independently Double-Gated (IDG) SOI CMOS (silicon on insulator, complementary metal oxide semiconductor) technology. Embedded ReBiLS circuits were integrated with a Reed-Solomon (RS) encoder using CMOS Ultra-Low-Power Radiation Tolerant (CULPRiT) double-gated digital logic circuits. The scope of the project includes: creation of a new high-voltage process, development of ReBiLS circuit designs, and adjustment of the designs to maximize performance through simulation, layout, and manufacture of prototypes. The primary technical objectives were to develop a high-voltage, thick oxide option for the 180-nm Flexfet process, and to develop a stand-alone ReBiLS IC with two 8-channel I/O busses, 1.8 2.5 I/O on the low-voltage pins, 5.0-V-tolerant input and 3.3-V output I/O on the high-voltage pins, and 100-MHz minimum operation with 10-pF external loads. Another objective was to develop an embedded, rad-hard ReBiLS I/O cell with 0.5-V low-voltage operation for interface with core logic, 5.0-V-tolerant input and 3.3-V output I/O pins, and 100-MHz minimum operation with 10- pF external loads. A third objective was to develop a 0.5- V Reed-Solomon Encoder with embedded ReBilS I/O: Transfer the existing CULPRiT RS encoder from a 0.35-micron bulk-CMOS process to the ASI 180-nm Flexfet, rad-hard SOI Process. 0.5-V low-voltage core logic. 5.0-V-tolerant input and 3.3-V output I/O pins. 100-MHz minimum operation with 10- pF external loads. The stand-alone ReBiLS chip will allow system designers to provide efficient bi-directional communication between components operating at different voltages. Embedding the ReBiLS cells into the proven Reed-Solomon encoder will demonstrate the ability to support new product development in a commercially viable, rad-hard, scalable 180-nm SOI CMOS process.

Fine root biomass in relation to site and stand characteristics in Norway spruce and Scots pine stands.

PubMed

Helmisaari, Heljä-Sisko; Derome, John; Nöjd, Pekka; Kukkola, Mikko

2007-10-01

Variations in fine root biomass of trees and understory in 16 stands throughout Finland were examined and relationships to site and stand characteristics determined. Norway spruce fine root biomass varied between 184 and 370 g m(-2), and that of Scots pine ranged between 149 and 386 g m(-2). In northern Finland, understory roots and rhizomes (< 2 mm diameter) accounted for up to 50% of the stand total fine root biomass. Therefore, the fine root biomass of trees plus understory was larger in northern Finland in stands of both tree species, resulting in a negative relationship between fine root biomass and the temperature sum and a positive relationship between fine root biomass and the carbon:nitrogen ratio of the soil organic layer. The foliage:fine root ratio varied between 2.1 and 6.4 for Norway spruce and between 0.8 and 2.2 for Scots pine. The ratio decreased for both Norway spruce and Scots pine from south to north, as well as from fertile to more infertile site types. The foliage:fine root ratio of Norway spruce was related to basal area and stem surface area. The strong positive correlations of these three parameters with fine root nitrogen concentration implies that more fine roots are needed to maintain a certain amount of foliage when nutrient availability is low. No significant relationships were found between stand parameters and fine root biomass at the stand level, but the relationships considerably improved when both fine root biomass and stand parameters were calculated for the mean tree in the stand. When the northern and southern sites were analyzed separately, fine root biomass per tree of both species was significantly correlated with basal area and stem surface area per tree. Basal area, stem surface area and stand density can be estimated accurately and easily. Thus, our results may have value in predicting fine root biomass at the tree and stand level in boreal Norway spruce and Scots pine forests.

Rainfall partitioning and related hydrochemical fluxes in a diverse and in a mono specific (Phenakospermum guyannense) secondary vegetation stand in eastern Amazonia.

PubMed

Hölscher, D; Sá, T D A; Möller, R F; Denich, M; Fölster, H

1998-04-01

Rainfall partitioning into throughfall and stemflow was studied in a diverse and in a mono specific stand of secondary vegetation in Eastern Amazonia. The nutrient concentrations in the water were analysed in order to quantify the related hydrochemical fluxes. Secondary vegetation forms the fallow in the local shifting cultivation system and is usually dominated by shrubs and trees. Phenakospermum guyannense (Strelitziaceae), a banana-like herb, is one of the predominant non-woody species. The study was conducted during an 18-month period in a 2.5-year-old relatively species-rich stand and a 10-year-old stand dominated by P. guyannense. In a year with 1956 mm of rainfall 65% (1281 mm) of this quantity reached the soil as throughfall in the diverse stand and 38% (743 mm) in the mono specific stand. Stemflow was estimated to be 23% and 41% respectively. P. guyannense and Banara guianensis (Flacourtiaceae), a tree species, were causing these high funnelling effects. In the young diverse stand B. guianensis had a stemflow of more than 200 l year -1 and P. guyannense had a median flux of 77 l year -1 per pseudostem. In the older stand the taller plants of P.␣guyannense collected 644 l year -1 per pseudostem on the median. The reason for these high values could be the banana-like growth form of P. guyannense and the crown morphology of B. guianensis, which has inclined branches. The low proportion of throughfall and the high stemflow values differ from all previous studies in Amazonian primary forests. The proximity to the Atlantic Ocean strongly influenced the nutrient fluxes via rainfall at our study site. This becomes obvious from the high Na and Cl fluxes with rainfall (19.7 kg Na ha -1 year -1 , 37.2 kg Cl ha -1 year -1 ) which were approximately equal to the Na and Cl fluxes with the sum of throughfall and stemflow for both stands. K fluxes in throughfall and stemflow in both stands were higher than in rainfall by a factor of 8. The high K enrichment during the crown passage is assumed to be caused by a␣high K concentration in the leaf tissue resulting in enhanced leaching from the leaves. In months with low␣rainfall the concentrations of Ca, Mg, S and Cl in throughfall of the diverse stand were significantly higher than in months with high rainfall. This was mainly due to vegetation burns in the dry period, which resulted in ash deposition on the canopy and subsequent wash-off and solution of ash particles.

Relationships between green anoles (Anolis carolinensis) and shrub-level vegetation in fire-maintained longleaf pine (Pinus palustris) forests of eastern Texas.

Treesearch

Richard R. Schaefer; Robert R. Fleet; D. Craig Rudolph; Nancy E. Koerth

2016-01-01

We examined habitat use by Anolis carolinensis (Green Anole) at perch heights ≤5 m, particularly in relation to woody shrub-level vegetation, in fire-maintained Pinus palustris (Longleaf Pine) forest stands on the Angelina National Forest in eastern Texas. We surveyed Green Anoles in 2 stands, within 20 established plots per...

The Missouri Ozark Forest Ecosystem Project: the effects of forest management on the forest ecosystem

Treesearch

Brian Brookshire; Carl Hauser

1993-01-01

The effects of forest management on non-timber resources are of growing concern to forest managers and the public. While many previous studies have reported effects of stand-level treatments (less than 15 ha) on various stand-level attributes, few studies have attempted to document the influence of forest management on the biotic and abiotic characteristics of entire...

Quality response of 29-year-old, even-aged central hardwoods after thinning

Treesearch

David L. Sonderman

1984-01-01

Describes the quality response of a 29-year-old upland hardwood stand grown for 6 years under different levels of residual stand density. Both the number of defects per square foot of surface area and the number of epicormic branches changed under different stocking levels. The results suggest that the effect of stocking on potential stem quality of certain species may...

Growth of ponderosa pine thinned to different stocking levels in the western United States

Treesearch

William W. Oliver; Carleton B. Edminster

1988-01-01

Growth of ponderosa pine was studied by the western Forest and Range Experiment Stations of the USDA Forest Service in response to increasing demands for better and more precise estimates of yields possible through intensive management. We summarized results of 15 to 20 years of growth after thinning each of five stands to a wide range of stocking levels. The stands-...

Growth of western larch after thinning from above and below to several density levels: 10-year results.

Treesearch

K.W. Seidel

1980-01-01

The 10-year growth of a 55-year-old, even-aged western larch (Larix occidentalis Nutt.) stand after it was thinned from above and below to a wide range of stocking levels was measured in eastern Oregon. Basal area and volume growth increased as stand density increased for both thinning methods. Despite heavy infestations of the larch casebearer...

Universities, Public Priorities, and the Future of Ontario. A Brief to the Standing Committee on Social Development of the Legislature of Ontario. Publication No. 83-9.

ERIC Educational Resources Information Center

Council of Ontario Universities, Toronto.

This brief was submitted to the Standing Committee on Social Development of the Ontario Legislature in connection with Bill 42, which is intended to limit university deficits. The following concerns are examined: current university funding levels in relation to enrollment and student demand, research responsibilities, tuition fee levels, and…

Growth and yield of western larch in response to several density levels and two thinning methods: 15-year results.

Treesearch

K.W. Seidel

1986-01-01

The 15-year growth response from a levels-of-growing-stock study in an even-aged western larch (Larix occidentalis Nutt.) stand, first thinned from above and below at age 55, was measured in northeastern Oregon. Basal area and volume growth increased with stand density for both thinning methods, whereas diameter growth decreased. Attacks of the...

All health is local: state and local planning for physical activity promotion.

PubMed

Kohl, Harold W; Satinsky, Sara B; Whitfield, Geoffrey P; Evenson, Kelly R

2013-01-01

Physical activity is a leading cause of death in the world. Although state and local public health planning is a useful strategy to address noncommunicable disease health concerns such as heart disease, diabetes, cancer, and obesity, physical activity frequently is subsumed in such disease-centric planning efforts. This strategy could dilute broader efforts to promote physical activity, create administrative silos that may be trying to accomplish similar goals, and weaken efforts to more collectively address a variety of noncommunicable diseases. Currently, few stand-alone state plans directed specifically at physical activity exist. The reasons and barriers for this situation are not understood. In 2011, we surveyed public health care practitioners to describe state and local efforts for physical activity planning. Cross-sectional study. Survey of physical activity practitioners in the United States. A total of 227 former or current members of the US National Society of Physical Activity Practitioners in Public Health who completed a survey. Overall, 48.0% of respondents indicated that they were aware of public health plans for physical activity promotion in their state, whereas 36.6% indicated that they did not know. Respondents at the state level more frequently reported awareness of a plan (62.1%) than those with local-level (52.4%) or other job responsibilities (36.0%). A greater proportion of respondents reported that stand-alone physical activity plans existed in their state than actually did exist in the respective states. Integration with the National Physical Activity Plan was least often identified as a moderately or extremely relevant aspect of a state-level physical activity plan, although it was chosen at a high percentage (75.7%). Respondents identified financial support (88.0%) and political will and support (54.6%) most frequently as very or somewhat difficult barriers to moving forward with state-level physical activity plans. These data suggest that despite efforts to increase development and use of stand-alone physical activity plans, most practitioners rely on existing chronic disease- or obesity-related plans to guide their efforts. Barriers to developing stand-alone physical activity plans must be addressed to develop such plans.

Effects of Stocking Rate on the Variability of Peak Standing Crop in a Desert Steppe of Eurasia Grassland

NASA Astrophysics Data System (ADS)

Wang, Zhongwu; Jiao, Shuying; Han, Guodong; Zhao, Mengli; Ding, Haijun; Zhang, Xinjie; Wang, Xiaoliang; Ayers, Eldon L.; Willms, Walter D.; Havsatad, Kris; A, Lata; Liu, Yongzhi

2014-02-01

Proper grazing management practices can generate corresponding compensatory effects on plant community production, which may reduce inter-annual variability of productivity in some grassland ecosystems. However, it remains unclear how grazing influences plant community attributes and the variability of standing crop. We examined the effects of sheep grazing at four stocking rate treatments [control, 0 sheep ha-1 month-1; light (LG), 0.15 sheep ha-1 month-1; moderate (MG), 0.30 sheep ha-1 month-1; and heavy (HG), 0.45 sheep ha-1 month-1] on standing crop at the community level and partitioned by species and functional groups, in the desert steppe of Inner Mongolia, China. The treatments were arranged in a completely randomized block design over a 9-year period. Standing crop was measured every August from 2004 to 2012. Peak standing crop decreased ( P < 0.05) with increasing stocking rate; peak standing crop in the HG treatment decreased 40 % compared to the control. May-July precipitation explained at least 76 % of the variation in peak standing crop. MG and HG treatments resulted in a decrease ( P < 0.05) in shrubs, semi-shrubs, and perennials forbs, and an increase ( P < 0.05) in perennial bunchgrasses compared to the control. The coefficients of variation at plant functional group and species level in the LG and MG treatments were lower ( P < 0.05) than in the control and HG treatments. Peak standing crop variability of the control and HG community were greatest, which suggested that LG and MG have greater ecosystem stability.

Characteristics of Declining Forest Stands on the Allegheny National Forest

Treesearch

William H. McWilliams; Robert White; Stanford L. Arner; Christopher, A. Nowak; Susan L. Stout; Susan L. Stout

1996-01-01

Forest stands with advanced symptoms of forest decline located on the Allegheny National Forest in northwestern Pennsylvania were studied to describe contemporary stand structure and composition, and the status of regeneration. Across all 340 stands, 12 percent of the total basal area per acre was in dead trees and 16 percent was in trees at high risk of mortality. For...

Log-grade volume distribution prediction models for tree species in red oak-sweetgum stands on US mid-south minor stream bottoms

Treesearch

George M. Banzhaf; Thomas G. Matney; Emily B. Schultz; James S. Meadows; J. Paul Jeffreys; William C. Booth; Gan Li; Andrew W. Ezell; Theodor D. Leininger

2016-01-01

Red oak (Quercus section Labatae)-sweetgum (Liquidambar styraciflua L.) stands growing on mid-south bottomland sites in the United States are well known for producing high-quality grade hardwood logs, but models for estimating the quantity and quality of standing grade wood in these stands have been unavailable. Prediction...

Human cerebral venous outflow pathway depends on posture and central venous pressure

PubMed Central

Gisolf, J; van Lieshout, J J; van Heusden, K; Pott, F; Stok, W J; Karemaker, J M

2004-01-01

Internal jugular veins are the major cerebral venous outflow pathway in supine humans. In upright humans the positioning of these veins above heart level causes them to collapse. An alternative cerebral outflow pathway is the vertebral venous plexus. We set out to determine the effect of posture and central venous pressure (CVP) on the distribution of cerebral outflow over the internal jugular veins and the vertebral plexus, using a mathematical model. Input to the model was a data set of beat-to-beat cerebral blood flow velocity and CVP measurements in 10 healthy subjects, during baseline rest and a Valsalva manoeuvre in the supine and standing position. The model, consisting of 2 jugular veins, each a chain of 10 units containing nonlinear resistances and capacitors, and a vertebral plexus containing a resistance, showed blood flow mainly through the internal jugular veins in the supine position, but mainly through the vertebral plexus in the upright position. A Valsalva manoeuvre while standing completely re-opened the jugular veins. Results of ultrasound imaging of the right internal jugular vein cross-sectional area at the level of the laryngeal prominence in six healthy subjects, before and during a Valsalva manoeuvre in both body positions, correlate highly with model simulation of the jugular cross-sectional area (R2 = 0.97). The results suggest that the cerebral venous flow distribution depends on posture and CVP: in supine humans the internal jugular veins are the primary pathway. The internal jugular veins are collapsed in the standing position and blood is shunted to an alternative venous pathway, but a marked increase in CVP while standing completely re-opens the jugular veins. PMID:15284348

The Importance of Acacia Trees for Insectivorous Bats and Arthropods in the Arava Desert

PubMed Central

Hackett, Talya D.; Korine, Carmi; Holderied, Marc W.

2013-01-01

Anthropogenic habitat modification often has a profound negative impact on the flora and fauna of an ecosystem. In parts of the Middle East, ephemeral rivers (wadis) are characterised by stands of acacia trees. Green, flourishing assemblages of these trees are in decline in several countries, most likely due to human-induced water stress and habitat changes. We examined the importance of healthy acacia stands for bats and their arthropod prey in comparison to other natural and artificial habitats available in the Arava desert of Israel. We assessed bat activity and species richness through acoustic monitoring for entire nights and concurrently collected arthropods using light and pit traps. Dense green stands of acacia trees were the most important natural desert habitat for insectivorous bats. Irrigated gardens and parks in villages and fields of date palms had high arthropod levels but only village sites rivalled acacia trees in bat activity level. We confirmed up to 13 bat species around a single patch of acacia trees; one of the richest sites in any natural desert habitat in Israel. Some bat species utilised artificial sites; others were found almost exclusively in natural habitats. Two rare species (Barbastella leucomelas and Nycteris thebaica) were identified solely around acacia trees. We provide strong evidence that acacia trees are of unique importance to the community of insectivorous desert-dwelling bats, and that the health of the trees is crucial to their value as a foraging resource. Consequently, conservation efforts for acacia habitats, and in particular for the green more densely packed stands of trees, need to increase to protect this vital habitat for an entire community of protected bats. PMID:23441145

Logging damage to residual trees following commercial harvesting to different overstory retention levels in a mature hardwood stand in Tennessee

Treesearch

Wayne K. Clatterbuck

2006-01-01

Partial cutting in mature hardwood stands often causes physical damage to residual stems through felling and skidding resulting in a decline in bole quality and subsequent loss of tree value. This study assessed the logging damage to residual trees following commercial harvesting in a fully stocked, mature oak-hickory stand cut to three overstory basal area retention...

Costs of reducing sapling basal area in thinned cherry-maple stands in West Virginia

Treesearch

Gary W. Miller

1984-01-01

Unmanaged 60-year-old cherry-maple stands in West Virginia were thinned to three levels of stocking according to the Allegheny hardwoods stocking guide. After the merchantable timber was removed, the basal area in saplings was reduced to less than 10 ft² per acre (2.3 m²/ha), as the guide recommends for stands with dense understories. A detailed time...

Aggregating pixel-level basal area predictions derived from LiDAR data to industrial forest stands in North-Central Idaho

Treesearch

Andrew T. Hudak; Jeffrey S. Evans; Nicholas L. Crookston; Michael J. Falkowski; Brant K. Steigers; Rob Taylor; Halli Hemingway

2008-01-01

Stand exams are the principal means by which timber companies monitor and manage their forested lands. Airborne LiDAR surveys sample forest stands at much finer spatial resolution and broader spatial extent than is practical on the ground. In this paper, we developed models that leverage spatially intensive and extensive LiDAR data and a stratified random sample of...

Secondary forest succession in a tropical dry forest: patterns of development across a 50-year chronosequence in lowland Bolivia

Treesearch

Deborah K. Kennard

2002-01-01

Stand structure, species richness and population structures of tree species were characterized in 12 stands representing 50 y of succession following slash-and-burn agriculture in a tropical dry forest in lowland Bolivia. Estimates of tree species richness, canopy cover and basal area reached or surpassed 75% of mature forest levels in the 5-, 8-, and 23-y-old stands...

Stand-level gas-exchange responses to seasonal drought in very young versus old Douglas-fir forests of the Pacific Northwest, USA

Treesearch

Sonia Wharton; Matt Schroeder; Ken Bible; Matthias Falk; Kyaw Tha Paw U

2009-01-01

This study examines how stand age affects ecosystem mass and energy exchange response to seasonal drought in three adjacent Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. The sites include two early seral (ES) stands (0 to 15 years old) and an old-growth (OG) (~450 to 500 years old) forest in the Wind River Experimental Forest,...

Inoculum reduction measures to manage Armillaria root disease in a severely infected stand of ponderosa pine in south-central Washington: 35-year results

Treesearch

Charles G. Shaw; D.W. Omdal; A. Ramsey-Kroll; L.F. Roth

2012-01-01

A stand of ponderosa pine (Pinus ponderosa) severely affected by Armillaria root disease was treated with five different levels of sanitation by root removal to reduce root disease losses in the regenerating stand. Treatments included the following: (1) all trees pushed over by machine, maximum removal of roots by machine ripping, and visible...

Stand structure and growth of Abies magnifica responded to five thinning levels in northeastern California, USA

Treesearch

Jianwei Zhang; William W. Oliver

2006-01-01

A 60-year old red fir stand with 23,950 stems per ha was thinned to five stand densities. Thinning occurred in 1972, 1976, and 1980. Height, DBH, and crown characteristics were measured seven times at four- to seven-year intervals from 1972 to 2002. Tree rings were measured retrospectively to determine growth of individual years. Periodic annual increment (PAI) was...

Effects of height and live crown ratio imputation strategies on stand biomass estimation

Treesearch

Elijah J. Allensworth; Temesgen. Hailemariam

2015-01-01

The effects of subsample design and imputation of total height (ht) and live crown ratio (cr) on the accuracy of stand-level estimates of component and total aboveground biomass are not well investigated in the current body of literature. To assess this gap in research, this study uses a data set of 3,454 Douglas-fir trees obtained from 102 stands in southwestern...

Forest volume-to-biomass models and estimates of mass for live and standing dead trees of U.S. forests.

Treesearch

James E. Smith; Linda S. Heath; Jennifer C. Jenkins

2003-01-01

Includes methods and equations for nationally consistent estimates of tree-mass density at the stand level (Mg/ha) as predicted by growing-stock volumes reported by the USDA Forest Service for forests of the conterminous United States. Developed for use in FORCARB, a carbon budget model for U.S. forests, the equations also are useful for converting plot-, stand- and...

Stand density-a factor affecting stem quality of young hardwoods

Treesearch

David L. Sonderman; David L. Sonderman

1985-01-01

A 14-year-old mixed oak stand was thinned in 1977 to stocking levels of 30, 50, and 60 percent and a control. From this stand, 117 trees were selected and their stem-related defects recorded. Six years later these same trees were reevaluated. The number of limb defects per square foot of surface area increased substantially more in the heavily thinned plots than in the...

Correlating sea level rise still-stands to marine terraces and undiscovered submerged shoreline features in the Channel Islands (USA) using autonomous and remotely operated systems

NASA Astrophysics Data System (ADS)

Raineault, N.; Ballard, R. D.; Fahy, J.; Mayer, L. A.; Heffron, E.; Krasnosky, K.; Roman, C.; Schmidt, V. E.; McLeod, A.; Bursek, J.; Broad, K.

2017-12-01

In 2017, the Ocean Exploration Trust aggregated onboard and autonomous mapping technologies to identify and explore paleo shorelines and discover previously undocumented submerged shoreline features in and around the Channel Islands offshore of California. Broad area mapping was conducted with the hull mounted multibeam echosounder aboard the E/V Nautilus. This Kongsberg EM302 provided maps at 2-10 m resolution, at depths generally greater than 50 m. From this data marine terraces were identified for higher resolution mapping via an Autonomous Surface Vehicle (ASV). The precision data from the ASV's Kongsberg EM2040p echosounder allowed identification of the knickpoints associated with cliffs on the landward extent of each terrace. Sub-sea cave targets were identified using backscatter and slope maps from a combination of both the broad area and high resolution multibeam data. To ground-truth the targets identified through mapping, remotely operated vehicles (ROVs) and a highly specialized team of cave divers explored these targets. The results from the visual inspection were then fed back into the analysis fostering the rapid iteration of the onboard identification criteria and resulted in locating submerged shorelines containing numerous large caves, arches, and concretions. Caves were found at still-stands at 8, 33, 66, and 103 m depth at Santa Cruz Island, Santa Barbara Island platform, and Osborn Bank, along the vertical escarpment at the cliff-face and aligned with the strike of fractures in the volcanic rock. These terraces correspond to different sea level still-stands. ROV grab samples of fossiliferous marine terraces will provide ages and aid in reconstructions of sea level change and tectonic history for each location. Finally, caves were mapped in sub-cm resolution using a Kongsberg M3 sonar mounted vertically on the front of the ROV to test the capabilities of the system to provide accurate information about exterior dimensions and morphology.

AORN Ergonomic Tool 4: Solutions for Prolonged Standing in Perioperative Settings.

PubMed

Hughes, Nancy L; Nelson, Audrey; Matz, Mary W; Lloyd, John

2011-06-01

Prolonged standing during surgical procedures poses a high risk of causing musculoskeletal disorders, including back, leg, and foot pain, which can be chronic or acute in nature. Ergonomic Tool 4: Solutions for Prolonged Standing in Perioperative Settings provides recommendations for relieving the strain of prolonged standing, including the use of antifatigue mats, supportive footwear, and sit/stand stools, that are based on well-accepted ergonomic safety concepts, current research, and access to new and emerging technology. Published by Elsevier Inc.

Pinus albicaulis Engelm. (whitebark pine) in mixed-species stands throughout its US range: Broad-scale indicators of extent and recent decline

Treesearch

Sara A. Goeking; Deborah Kay Izlar

2018-01-01

We used data collected from >1400 plots by a national forest inventory to quantify population-level indicators for a tree species of concern. Whitebark pine (Pinus albicaulis) has recently experienced high mortality throughout its US range, where we assessed the area of land with whitebark pine present, size-class distribution of individual whitebark pine,...

Manipulating stand structure of Douglas-fir plantations for wildlife habitat and wood production

Treesearch

Timothy B. Harrington

2010-01-01

In southwestern Oregon, a study was initiated by Oregon State University (OSU) in 1983 to determine effects of hardwood competition on Douglas-fir plantation development. The use of herbicides to uniformly suppress competing vegetation—especially fast-growing hardwoods—proved to be an effective approach to ensure dominance and a high level of productivity for planted...

Establishment and Growth of Cherrybark Oak Seedlings Underplanted Beneath a Partial Overstory in a Minor Bottom of Southwestern Arkansas: First Year Results

Treesearch

Emile S. Gardiner; Jimmie L. Yeiser

1999-01-01

Advance regeneration is frequently inadequate to sufficiently restock the oak component of many bottomland stands, especially on productive sites with high levels of competition. We initiated a study near Beime, AR to examine the effects of pre-plant control of Japanese honeysuckle (Lonicera japonica Thunberg) and seedling quality on establishment...

Genetic effects on stand-level uniformity, and above- and belowground dry mass production in juvenile loblolly pine

Treesearch

Michael J. Aspinwall; John S. King; Steven E. McKeand; Bronson P. Bullock

2012-01-01

Several decades of tree improvement operations have drastically increased loblolly pine plantation productivity in the southern U.S. (McKeand et al., 2003). This work has lead to the availability of a number of highly productive open-pollinated and full-sib families (McKeand et al., 2006). In addition, vegetative propagation (somatic embryogenesis) has also made it...

Consumption and reaccumulation of forest fuels in oak shelterwood stands managed with prescribed fire

Treesearch

Patrick H. Brose

2016-01-01

In the shelterwood-burn technique, a moderate- to high-intensity growing-season prescribed fire is essential to achieve desired oak regeneration goals. These levels of fire intensity are dependent on the increased fuel loadings created by the preceding first removal cut. However, the loadings of forest fuels and their fluctuation during implementation of the...

Comparison of Lumbar Lordosis in Lateral Radiographs in Standing Position with supine MR Imaging in consideration of the Sacral Slope.

PubMed

Benditz, Achim; Boluki, Daniel; Weber, Markus; Zeman, Florian; Grifka, Joachim; Völlner, Florian

2017-03-01

Purpose  To investigate the influence of sacral slope on the correlation between measurements of lumbar lordosis obtained by standing radiographs and magnetic resonance images in supine position (MRI). Little information is available on the correlation between measurements of lumbar lordosis obtained by radiographic and MR images. Most relevant studies have shown correlations for the thoracic spine, but detailed analyses on the lumbar spine are lacking. Methods  MR images and standing lateral radiographs of 63 patients without actual low back pain or radiographic pathologies of the lumbar spine were analyzed. Standing radiographic measurements included the sagittal parameters pelvic incidence (PI) pelvic tilt (PT), and sacral slope (SS); MR images were used to additionally measure lumbar L1-S1 lordosis and single level lordosis. Differences between radiographic and MRI measurements were analyzed and divided into 4 subgroups of different sacral slope according to Roussouly's classification. Results  Global lumbar lordosis (L1-S1) was 44.99° (± 10 754) on radiographs and 47.91° (± 9.170) on MRI, yielding a clinically relevant correlation (r = 0.61, p < 0.01). Measurements of single level lordosis only showed minor differences. At all levels except for L5 / S1, lordosis measured by means of standing radiographs was higher than that measured by MRI. The difference in global lumbar L1-S1 lordosis was -2.9°. Analysis of the Roussouly groups showed the largest difference for L1-S1 (-8.3°) in group 2. In group 4, when measured on MRI, L5 / S1 lordosis (25.71°) was lower than L4 / L5 lordosis (27.63°) compared to the other groups. Conclusions  Although measurements of global lumbar lordosis significantly differed between the two scanning technologies, the mean difference was just 2.9°. MRI in supine position may be used for estimating global lumbar lordosis, but single level lordosis should be determined by means of standing radiographs. Key Points   · Large difference between radiographic and MRI measurements of level L5 / S1.. · MRI can be used for estimating global lumbar lordosis.. · Analysis of single level lordosis necessitates measurement in standing radiographs.. Citation Format · Benditz A, Boluki D, Weber M et al. Comparison of Lumbar Lordosis in Lateral Radiographs in Standing Position with supine MR Imaging in consideration of the Sacral Slope. Fortschr Röntgenstr 2017; 189: 233 - 239. © Georg Thieme Verlag KG Stuttgart · New York.

Optimal Adherence to a Mediterranean Diet and High Muscular Fitness Are Associated with a Healthier Cardiometabolic Profile in Collegiate Students

PubMed Central

Correa-Bautista, Jorge Enrique; Ojeda-Pardo, Mónica Liliana; Sandoval-Cuellar, Carolina; González-Ruíz, Katherine; Prieto-Benavides, Daniel Humberto; Tordecilla-Sanders, Alejandra; Martinkėnas, Arvydas

2018-01-01

The aim of the study was to investigate the combined association of adherence to a Mediterranean diet (MedDiet) and muscular fitness (MF) with cardiometabolic health in collegiate students. The present cross-sectional analysis consisted of 1248 (714 females) healthy collegiate students (20.1 ± 2.7 years old). Adherence to a MedDiet was assessed by a KIDMED (Mediterranean Diet Quality Index) questionnaire. Standing broad jump, standing vertical jump, and isometric handgrip dynamometry were used as indicators of MF. The cardiometabolic profile was assessed using the following components: triglycerides, blood pressure, triglycerides, high-density lipoprotein (HDL)-cholesterol, glucose, and waist circumference. Analysis of covariance shows a significant difference in the cardiometabolic profile of both genders between the high MF/low MedDiet and high MF/optimal MedDiet groups, and the low MF/low MedDiet and low MF/optimal MedDiet groups (p < 0.001). No difference was found on cardiometabolic profile between high MF/optimal MedDiet and high MF/low MedDiet, both in males and females. Additionally, logistic regression shows that both female (odds ratio (OR) = 2.01; 95% confidence interval (CI): (1.8–3.7); p = 0.02) and male (OR = 3.38; 95% CI: (1.9–5.8); p < 0.001) participants in the optimal MedDiet/high MF group had the highest odds of expressing a healthier cardiometabolic profile as compared to those in the low MF/low MedDiet group. In conclusion, a combination of high MF levels and optimal adherence to a MedDiet is associated with a healthier cardiometabolic profile; however, high MF levels seem to circumvent the deleterious effects of having a low adherence to a MedDiet. PMID:29677099

Optimal Adherence to a Mediterranean Diet and High Muscular Fitness Are Associated with a Healthier Cardiometabolic Profile in Collegiate Students.

PubMed

Ramírez-Vélez, Robinson; Correa-Bautista, Jorge Enrique; Ojeda-Pardo, Mónica Liliana; Sandoval-Cuellar, Carolina; García-Hermoso, Antonio; Carrillo, Hugo Alejandro; González-Ruíz, Katherine; Prieto-Benavides, Daniel Humberto; Tordecilla-Sanders, Alejandra; Martinkėnas, Arvydas; Agostinis-Sobrinho, César

2018-04-20

The aim of the study was to investigate the combined association of adherence to a Mediterranean diet (MedDiet) and muscular fitness (MF) with cardiometabolic health in collegiate students. The present cross-sectional analysis consisted of 1248 (714 females) healthy collegiate students (20.1 ± 2.7 years old). Adherence to a MedDiet was assessed by a KIDMED (Mediterranean Diet Quality Index) questionnaire. Standing broad jump, standing vertical jump, and isometric handgrip dynamometry were used as indicators of MF. The cardiometabolic profile was assessed using the following components: triglycerides, blood pressure, triglycerides, high-density lipoprotein (HDL)-cholesterol, glucose, and waist circumference. Analysis of covariance shows a significant difference in the cardiometabolic profile of both genders between the high MF/low MedDiet and high MF/optimal MedDiet groups, and the low MF/low MedDiet and low MF/optimal MedDiet groups ( p < 0.001). No difference was found on cardiometabolic profile between high MF/optimal MedDiet and high MF/low MedDiet, both in males and females. Additionally, logistic regression shows that both female (odds ratio (OR) = 2.01; 95% confidence interval (CI): (1.8⁻3.7); p = 0.02) and male (OR = 3.38; 95% CI: (1.9⁻5.8); p < 0.001) participants in the optimal MedDiet/high MF group had the highest odds of expressing a healthier cardiometabolic profile as compared to those in the low MF/low MedDiet group. In conclusion, a combination of high MF levels and optimal adherence to a MedDiet is associated with a healthier cardiometabolic profile; however, high MF levels seem to circumvent the deleterious effects of having a low adherence to a MedDiet.

Standing Waves in an Elastic Spring: A Systematic Study by Video Analysis

NASA Astrophysics Data System (ADS)

Ventura, Daniel Rodrigues; de Carvalho, Paulo Simeão; Dias, Marco Adriano

2017-04-01

The word "wave" is part of the daily language of every student. However, the physical understanding of the concept demands a high level of abstract thought. In physics, waves are oscillating variations of a physical quantity that involve the transfer of energy from one point to another, without displacement of matter. A wave can be formed by an elastic deformation, a variation of pressure, changes in the intensity of electric or magnetic fields, a propagation of a temperature variation, or other disturbances. Moreover, a wave can be categorized as pulsed or periodic. Most importantly, conditions can be set such that waves interfere with one another, resulting in standing waves. These have many applications in technology, although they are not always readily identified and/or understood by all students. In this work, we use a simple setup including a low-cost constant spring, such as a Slinky, and the free software Tracker for video analysis. We show they can be very useful for the teaching of mechanical wave propagation and the analysis of harmonics in standing waves.

Around Marshall

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. Looking North, this aerial taken January 15, 1963, gives a closer view of the deep hole for the F-1 test stand site in the forefront. The S-IC test stand with towers prominent is to the right of center, and the Block House is seen left of center.

Around Marshall

NASA Image and Video Library

1963-11-20

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo shows the progress of the F-1 Test Stand as of November 20, 1963.

Around Marshall

NASA Image and Video Library

1963-04-04

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken April 4, 1963 depicts the construction of the F-1 test stand foundation walls.

Around Marshall

NASA Image and Video Library

1963-04-17

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken April 17, 1963 depicts the construction of the F-1 test stand foundation walls.

The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease

PubMed Central

Jazaeri, Seyede Zohreh; Azad, Akram; Mehdizadeh, Hajar; Habibi, Seyed Amirhassan; Mandehgary Najafabadi, Mahbubeh; Saberi, Zakieh Sadat; Rahimzadegan, Hawre; Moradi, Saeed; Behzadipour, Saeed; Parnianpour, Mohamad; Khalaf, Kinda

2018-01-01

Background Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. Objectives This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. Methods Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). Results Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. Conclusion The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans. PMID:29390029

Three-dimensional instability of standing waves

NASA Astrophysics Data System (ADS)

Zhu, Qiang; Liu, Yuming; Yue, Dick K. P.

2003-12-01

We investigate the three-dimensional instability of finite-amplitude standing surface waves under the influence of gravity. The analysis employs the transition matrix (TM) approach and uses a new high-order spectral element (HOSE) method for computation of the nonlinear wave dynamics. HOSE is an extension of the original high-order spectral method (HOS) wherein nonlinear wave wave and wave body interactions are retained up to high order in wave steepness. Instead of global basis functions in HOS, however, HOSE employs spectral elements to allow for complex free-surface geometries and surface-piercing bodies. Exponential convergence of HOS with respect to the total number of spectral modes (for a fixed number of elements) and interaction order is retained in HOSE. In this study, we use TM-HOSE to obtain the stability of general three-dimensional perturbations (on a two-dimensional surface) on two classes of standing waves: plane standing waves in a rectangular tank; and radial/azimuthal standing waves in a circular basin. For plane standing waves, we confirm the known result of two-dimensional side-bandlike instability. In addition, we find a novel three-dimensional instability for base flow of any amplitude. The dominant component of the unstable disturbance is an oblique (standing) wave oriented at an arbitrary angle whose frequency is close to the (nonlinear) frequency of the original standing wave. This finding is confirmed by direct long-time simulations using HOSE which show that the nonlinear evolution leads to classical Fermi Pasta Ulam recurrence. For the circular basin, we find that, beyond a threshold wave steepness, a standing wave (of nonlinear frequency Omega) is unstable to three-dimensional perturbations. The unstable perturbation contains two dominant (standing-wave) components, the sum of whose frequencies is close to 2Omega. From the cases we consider, the critical wave steepness is found to generally decrease/increase with increasing radial/azimuthal mode number of the base standing wave. Finally, we show that the instability we find for both two- and three-dimensional standing waves is a result of third-order (quartet) resonance.

Using sit-stand workstations to decrease sedentary time in office workers: a randomized crossover trial.

PubMed

Dutta, Nirjhar; Koepp, Gabriel A; Stovitz, Steven D; Levine, James A; Pereira, Mark A

2014-06-25

This study was conducted to determine whether installation of sit-stand desks (SSDs) could lead to decreased sitting time during the workday among sedentary office workers. A randomized cross-over trial was conducted from January to April, 2012 at a business in Minneapolis. 28 (nine men, 26 full-time) sedentary office workers took part in a 4 week intervention period which included the use of SSDs to gradually replace 50% of sitting time with standing during the workday. Physical activity was the primary outcome. Mood, energy level, fatigue, appetite, dietary intake, and productivity were explored as secondary outcomes. The intervention reduced sitting time at work by 21% (95% CI 18%-25%) and sedentary time by 4.8 min/work-hr (95% CI 4.1-5.4 min/work-hr). For a 40 h work-week, this translates into replacement of 8 h of sitting time with standing and sedentary time being reduced by 3.2 h. Activity level during non-work hours did not change. The intervention also increased overall sense of well-being, energy, decreased fatigue, had no impact on productivity, and reduced appetite and dietary intake. The workstations were popular with the participants. The SSD intervention was successful in increasing work-time activity level, without changing activity level during non-work hours.

Steel shear strength of anchors with stand-off base plates.

DOT National Transportation Integrated Search

2013-09-01

Sign and signal structures are often connected to concrete foundations through a stand-off annular base plate with a double-nut anchor bolt connection, which leaves exposed anchor bolt lengths below leveling nuts used in these connections. Cantilever...

Effectiveness of standing frame on constipation in children with cerebral palsy: a single-subject study.

PubMed

Rivi, Elena; Filippi, Mariacristina; Fornasari, Elisa; Mascia, Maria Teresa; Ferrari, Adriano; Costi, Stefania

2014-09-01

Children with cerebral palsy (CP) and quadriplegia or severe diplegia suffer from highly reduced mobility and consequent constipation. Clinicians recommend standing frames to exercise the support reaction in this population, sharing the opinion that the upright position may facilitate intestinal transit, although no evidence supports this assumption. We conducted this study to determine the effects of the standing frame on spontaneous evacuation in children with CP. Moreover, we studied its effects on the frequency of induction of evacuation, the characteristics of the stool and the pain suffered by the child due to constipation and/or evacuation. We implemented a single-subject research design in one chronically constipated child with CP and quadriplegia, Gross Motor Function Classification System Level V. To monitor the effects of the standing frame, we measured the outcome of interest throughout the study using a daily diary and the Bristol Stool Scale. This study was approved by the local Ethics Committee. This study has several limitation; primarily, the use of a single-subject research design only makes possible the visual analysis of data obtained from a unique patient. So, by themselves, data obtained do not allow us any generalization for the target population. Future research should verify our results collecting more data and also investigating the effect of the standing-frame on respiratory functions. Although the standing frame did not affect the frequency of evacuations or the characteristics of the stool, its employment reduced the inductions of evacuation and the related pain suffered by the child. However, this study has several limitations, such as the lack of generalization due to the fact that we studied a unique patient and the overall brevity of the study due to external circumstances. Therefore, we suggest future research to verify our results, also investigating the effect of the standing frame on respiratory functions. Relevance to clinical practice. The standing frame may positively influence the management of constipation of these children, possibly improving their quality of life. Copyright © 2014 John Wiley & Sons, Ltd.

Effects of planting density and genotype on loblolly pine stands growing in the mountains of southeastern Oklahoma

Treesearch

Rodney E. Will; Thomas C. Hennessey; Thomas B. Lynch; Robert Heinemann; Randal Holeman; Dennis Wilson; Keith Anderson; Gregory Campbell

2013-01-01

We determined the effects of planting density (4- by 4-, 6- by 6-, 8- by 8-, and 10- by 10-foot spacing) on stand-level height, diameter at breast height, stem volume, basal area, and periodic annual increment for two loblolly pine (Pinus taeda L.) seed sources. Seed sources for the 25-year-old stands were a North Carolina seed source (NCC 8-01) and...

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands - II. Development of Intermediate and Suppressed Trees Following Release in Natural Stands

Treesearch

James B. Baker; Michael G. Shelton

1998-01-01

Development of 86 intermediate and suppressed loblolly pine (Pinus taeda L.) trees, that had been recently released from overtopping pines and hardwoods, was monitored over a 15 year period. The trees were growing in natural stands on good sites (site index = 90 ft at 50 years) that had been recently cut to stocking levels ranging from 10 to 50 percent. At time of...

Digit ratio (2D:4D) and physical fitness (Eurofit test battery) in school children.

PubMed

Ranson, R; Stratton, G; Taylor, S R

2015-05-01

The relative lengths of the index finger to the ring finger (2D:4D) is sexually dimorphic and is thought to be a correlate of prenatal sex steroids (low 2D:4D=high prenatal testosterone and low prenatal oestrogen). In adults there have been reports that low 2D:4D is consistently associated with high sports performance. To investigate correlations between 2D:4D and fitness levels in children. Right 2D:4D and body size were measured, in addition to flexibility, speed, endurance and strength (Eurofit tests). 922 boys and 835 girls (mean ages (years): 10.8 ± 1.01 and 10.07 ± 1.00 respectively). height, mass, BMI, triceps and subscapular skinfolds, 20 m shuttle run, sit and reach, standing broad jump, hand grip strength, 10 × 5m sprint, and the sit and reach test. Boys significantly outperformed the girls in the 10 × 5m sprints, the 20 m shuttle run, standing broad jump, and hand grip strength. In boys but not girls, 2D:4D was significantly negatively correlated with scores in all these tests except the standing broad jump. In girls but not boys, 2D:4D was significantly positively correlated to stature, mass, BMI and waist circumference. It is suggested that high prenatal testosterone and low prenatal oestrogen (low 2D:4D) is implicated in high sprinting speed, endurance and hand grip strength in boys. In girls low prenatal testosterone and high prenatal oestrogen is associated with large body size. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Workplace standing time and the incidence of obesity and type 2 diabetes: a longitudinal study in adults.

PubMed

Chaput, Jean-Philippe; Saunders, Travis J; Tremblay, Mark S; Katzmarzyk, Peter T; Tremblay, Angelo; Bouchard, Claude

2015-02-10

It is increasingly recognized that standing represents a simple solution to extended periods of sitting. However, it is currently unknown whether workplace standing time is prospectively associated with a lower incidence of chronic diseases. The objective of this study was to examine the association between workplace standing time and the incidence of overweight/obesity (OW/OB) and impaired glucose tolerance/type 2 diabetes (IGT/T2D) in adults. A longitudinal analysis from the Quebec Family Study (Canada) was conducted on 293 participants, aged 18 to 65 years, followed for a mean of 6 years. Information on self-reported occupational standing time as well as several covariates was collected at both baseline and follow-up. Outcome measures included the development of OW/OB (i.e. body mass index ≥25 kg/m(2)) and IGT/T2D (i.e. 2-h postload plasma glucose level ≥7.8 mmol/L). The incidence rates of OW/OB and IGT/T2D over the 6-year follow-up period were 17.4% and 12.6%, respectively. Significant negative associations were observed between the amount of occupational standing time and the development of outcome measures. However, the associations were no longer significant after adjustment for age, sex, smoking habits, total annual family income, daily caloric intake, and submaximal working capacity. In age- and sex-adjusted logistic regression analysis, significant negative linear trends were observed across levels of standing time and the outcome variables. However, the associations were no longer significant after further adjustment for the other covariates. Finally, we observed that the change in standing time from baseline to year 6 was significantly associated with the development of outcome measures, with higher incidence rates in adults reporting a reduction in standing time at follow-up. However, the associations became non-significant after adjustment for covariates. Greater occupational standing time is not sufficient in and of itself to prevent the development of OW/OB and IGT/T2D in adults. Future efforts are needed to better understand the potential benefits of higher amounts of standing time throughout the day on the prevention of chronic diseases.

Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population.

PubMed

Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

2016-01-01

Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects.

Comparison of Standing Posture Bioelectrical Impedance Analysis with DXA for Body Composition in a Large, Healthy Chinese Population

PubMed Central

Chen, Kuen-Tsann; Chen, Yu-Yawn; Wang, Chia-Wei; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Lu, Hsueh-Kuan; Dwyer, Gregory B.; Chao, Shu-Ping; Shih, Ming-Kuei; Hsieh, Kuen-Chang

2016-01-01

Bioelectrical impedance analysis (BIA) is a common method for assessing body composition in research and clinical trials. BIA is convenient but when compared with other reference methods, the results have been inconclusive. The level of obesity degree in subjects is considered to be an important factor affecting the accuracy of the measurements. A total of 711 participants were recruited in Taiwan and were sub-grouped by gender and levels of adiposity. Regression analysis and Bland-Altman analysis were used to evaluate the agreement of the measured body fat percentage (BF%) between BIA and DXA. The BF% measured by the DXA and BIA methods (Tanita BC-418) were expressed as BF%DXA and BF%BIA8, respectively. A one-way ANOVA was used to test the differences in BF% measurements by gender and levels of adiposity. The estimated BF%BIA8 and BF%DXA in the all subjects, male and female groups were all highly correlated (r = 0.934, 0.901, 0.916, all P< 0.001). The average estimated BF%BIA8 (22.54 ± 9.48%) was significantly lower than the average BF%DXA (26.26 ± 11.18%). The BF%BIA8 was overestimated in the male subgroup (BF%DXA< 15%), compared to BF%DXA by 0.45%, respectively. In the other subgroups, the BF%BIA8 values were all underestimated. Standing BIA estimating body fat percentage in Chinese participants have a high correlation, but underestimated on normal and high obesity degree in both male and female subjects. PMID:27467065

Free-standing, well-aligned ordered mesoporous carbon nanofibers on current collectors for high-power micro-supercapacitors.

PubMed

Kang, Eunae; Jeon, Gumhye; Kim, Jin Kon

2013-07-21

The mesoporous carbon nanofiber arrays that stand on carbon-gold double-layer current collectors are synthesized by self-assembly of a PS-b-PEO copolymer and resol in AAO templates for a high-power micro-supercapacitor at high current densities.

Development of a Transient Thrust Stand with Sub-Millisecond Resolution

NASA Astrophysics Data System (ADS)

Spells, Corbin Fraser

The transient thrust stand has been developed to offer 0.1 ms time resolved thrust measurements for the characterization of mono-propellant thrusters for spacecraft applications. Results demonstrated that the system was capable of obtaining dynamic thrust profiles within 5 % and 0.1 ms. Measuring and improving the thrust performance of mono-propellant thrusters will require 1 ms time resolved forces to observe shot-to-shot variations, oscillations, and minimum impulse bits. To date, no thrust stand is capable of measuring up to 22 N forces with a time response of up to 10 kHz. Calibration forces up to 22 N with a frequency response greater than 0.1 ms were obtained using voice coil actuators. Steady state and low frequency measurements were obtained using displacement and velocity sensors and were combined with high frequency vibration modes measured using several accelerometers along the thrust stand arm. The system uses a predictor-based subspace algorithm to obtain a high order state space model of the thrust stand capable of defining the high frequency vibration modes. The high frequency vibration modes are necessary to provide the time response of 0.1 ms. Thruster forces are estimated using an augmented Kalman filter to combine sensor traces from four accelerometers, a velocity sensor, and displacement transducer. Combining low frequency displacement data with high frequency acceleration measurements provides accurate force data across a broad time domain. The transient thrust stand uses a torsional pendulum configuration to minimize influence from external vibration and achieve high force resolution independent of thruster weight.

Contrasted nitrogen utilization in annual C 3 grass and legume crops: Physiological explorations and ecological considerations

NASA Astrophysics Data System (ADS)

Del Pozo, Alejandro; Garnier, Eric; Aronson, James

2000-01-01

Although it is well known that legumes have unusually high levels of nitrogen in both reproductive and vegetative organs, the physiological implications of this pattern have been poorly assessed. We conducted a literature survey and used data from two (unpublished) experiments on annual legumes and C 3 grasses in order to test whether these high nitrogen concentrations in legumes are correlated to high rates of carbon gain. Three different temporal/spatial scales were considered: full growing season/stand, days to month/whole plant and seconds/leaf. At the stand level, and for plants grown under both extratropical and tropical settings, biomass per unit organic-nitrogen was lower in legume than in grass crops. At a shorter time scale, the relative growth rate per unit plant nitrogen (`nitrogen productivity') was lower in faba bean ( Vicia faba var. minor cv. Tina) than in wheat ( Triticum aestivum cv. Alexandria), and this was confirmed in a comparison of two wild, circum-Mediterranean annuals - Medicago minima, a legume, and Bromus madritensis, a grass. Finally, at the leaf level, a synthesis of published data comparing soybean ( Glycine max) and rice ( Oryza sativa) on the one hand, and our own data on faba bean and wheat on the other hand, demonstrates that the photosynthetic rate per unit leaf nitrogen (the photosynthetic nitrogen use efficiency) is consistently lower in legumes than in grasses. These results demonstrate that, regardless of the scale considered and although the organic-nitrogen concentration in vegetative organs of legumes is higher than in grasses, this does not lead to higher rates of carbon gain in the former. Various physiological factors affecting the efficiency of nitrogen utilization at the three time scales considered are discussed. The suggestion is made that the ecological significance of the high nitrogen concentration in legumes may be related to a high nitrogen demand for high quality seed production at a time when nitrogen fixation is shut off rather than to a high production potential.

Orthostatic responses at 4860 m in low, moderate, and high altitude residents.

PubMed

Davis, John E; Wagner, Dale R; Thorington, Jessica; Schall, Cory

2013-09-01

This study evaluated the influence of altitude of residence on orthostatic responses when exposed to high altitude. Data collection took place at the Carrel hut (4860 m) on Chimborazo in Ecuador. After being transported to the hut by vehicle, 69 people volunteered for the study. A 3-min stand test (rapid change from supine to standing) provided an orthostatic challenge while resting heart rate (RHR), systolic (SBP) and diastolic (DBP) blood pressures, and arterial oxygen saturation (SpO2) were measured. Participants were separated into four groups based on altitude of residence and ethnicity: LOW (<1500 m; n=15), MOD (1500-3000 m, n=30), and HIGH (>3000 m, n=11) Ecuadorians, and non-Ecuadorian lowlanders (NE-LOW, n=13). Supine and standing RHRs were lower (p<0.05) for HIGH compared to other groups. Furthermore, standing increased RHR in LOW, MOD, and NE-LOW by 11.9 ± 5.3, 9.5 ± 4.1, and 11.6 ± 7.4 bpm, respectively, while HIGH stayed the same (0.6 bpm increase ± 3.3). Additionally, mean arterial pressure decreased slightly but not significantly upon standing in all groups except HIGH. The difference in Spo2 among groups was not significant (p>0.05). Altitude of residence influences the cardiovascular responses to orthostatic stress with HIGH having blunted responses and greater tolerance.

Movement variability and skill level of various throwing techniques.

PubMed

Wagner, Herbert; Pfusterschmied, Jürgen; Klous, Miriam; von Duvillard, Serge P; Müller, Erich

2012-02-01

In team-handball, skilled athletes are able to adapt to different game situations that may lead to differences in movement variability. Whether movement variability affects the performance of a team-handball throw and is affected by different skill levels or throwing techniques has not yet been demonstrated. Consequently, the aims of the study were to determine differences in performance and movement variability for several throwing techniques in different phases of the throwing movement, and of different skill levels. Twenty-four team-handball players of different skill levels (n=8) performed 30 throws using various throwing techniques. Upper body kinematics was measured via an 8 camera Vicon motion capture system and movement variability was calculated. Results indicated an increase in movement variability in the distal joint movements during the acceleration phase. In addition, there was a decrease in movement variability in highly skilled and skilled players in the standing throw with run-up, which indicated an increase in the ball release speed, which was highest when using this throwing technique. We assert that team-handball players had the ability to compensate an increase in movement variability in the acceleration phase to throw accurately, and skilled players were able to control the movement, although movement variability decreased in the standing throw with run-up. Copyright © 2011 Elsevier B.V. All rights reserved.

Around Marshall

NASA Image and Video Library

1963-09-18

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. This photograph taken September 18, 1963 shows a spherical hydrogen tank being constructed next to the S-IC test stand.

The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States.

PubMed

Clark, James S; Iverson, Louis; Woodall, Christopher W; Allen, Craig D; Bell, David M; Bragg, Don C; D'Amato, Anthony W; Davis, Frank W; Hersh, Michelle H; Ibanez, Ines; Jackson, Stephen T; Matthews, Stephen; Pederson, Neil; Peters, Matthew; Schwartz, Mark W; Waring, Kristen M; Zimmermann, Niklaus E

2016-07-01

We synthesize insights from current understanding of drought impacts at stand-to-biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand-level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition and structure, and shifting range limits are widely observed. In the eastern US, the effects of increasing drought are becoming better understood at the level of individual trees, but this knowledge cannot yet be confidently translated to predictions of changing structure and diversity of forest stands. While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought. Throughout the continental United States, the combination of projected large climate-induced shifts in suitable habitat from modeling studies and limited potential for the rapid migration of tree populations suggests that changing tree and forest biogeography could substantially lag habitat shifts already underway. Forest management practices can partially ameliorate drought impacts through reductions in stand density, selection of drought-tolerant species and genotypes, artificial regeneration, and the development of multistructured stands. However, silvicultural treatments also could exacerbate drought impacts unless implemented with careful attention to site and stand characteristics. Gaps in our understanding should motivate new research on the effects of interactions involving climate and other species at the stand scale and how interactions and multiple responses are represented in models. This assessment indicates that, without a stronger empirical basis for drought impacts at the stand scale, more complex models may provide limited guidance. © 2016 John Wiley & Sons Ltd.

Experience with the selection method in pine stands in the southern United States, with implications for future application

Treesearch

James M. Guldin

2011-01-01

The selection method applied in shade-intolerant pine stands in the southern United States has been shown to be an effective method of uneven-aged silviculture, but it is becoming less frequently practiced for a variety of reasons. Economically, the high value of standing timber puts fully stocked uneven-aged pine stands at risk of liquidation if the timberland is sold...

n/a

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This aerial photograph, taken January 15, 1963, gives a close overall view of the newly developed test complex. Depicted in the forefront center is the S-IC test stand with towers prominent, the Block House is seen in the center just above the S-IC test stand, and the large hole to the left, located midway between the two is the F-1 test stand site.

n/a

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This aerial photograph, taken January 15, 1963 gives an overall view of the construction progress of the newly developed test complex. The large white building located in the center is the Block House. Just below and to the right of it is the S-IC test stand. The large hole to the left of the S-IC stand is the F-1 test stand site.

Around Marshall

NASA Image and Video Library

1963-08-13

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of August 13, 1963. All four of its tower legs are well underway into the skyline.

Around Marshall

NASA Image and Video Library

1963-01-14

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were constructed during this time frame. Built just north of the massive S-IC test stand was the F-1 Engine test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken January 14, 1963 depicts the F-1 test stand site with hoses pumping excess water from the site.

Comparison of plate-cage construct and stand-alone anchored spacer in the surgical treatment of three-level cervical spondylotic myelopathy: a preliminary clinical study.

PubMed

Shi, Sheng; Liu, Zu-De; Li, Xin-Feng; Qian, Lie; Zhong, Gui-Bin; Chen, Fang-Jing

2015-09-01

Although stand-alone cages were advocated to be superior to plate-cage construct (PCC) because of comparable clinical outcomes and fewer plate-related complications, cage dislocation and subsidence were frequently mentioned in multilevel fusion. There are some concerns about whether these issues can be effectively prevented in multilevel anterior cervical discectomy and fusion (ACDF) by stand-alone anchored spacer (SAAS). The aim was to compare clinical outcomes, radiologic parameters, and complications of PCC and SAAS in the treatment of three-level cervical spondylotic myelopathy (CSM). This was a retrospective comparative study. A total of 38 consecutive patients with three-level CSM (ACDF with PCC, 20 patients; ACDF with SAAS, 18 patients) were reviewed. Clinical outcomes were assessed using Japanese Orthopaedic Association and Neck Disability Index. The radiologic evaluations included cervical alignment (CA), segmental angle (SA), postoperative curvature loss (PCL), and incidence of subsidence. All the aforementioned parameters were compared before and after surgery between two groups. Besides, the aforementioned results were also compared between the two groups. The complications were also recorded. The mean follow-up period was 30.3 months. No significant differences were observed in clinical outcomes between the two groups (p>.05). Additionally, no significant differences existed in fusion rate between the two groups. There were significant differences in PCL of SA and CA and correction of SA between the two groups (p<.05). Besides, the incidence of subsidence (9 of 54 levels, 16.7%) was recorded in the SAAS group, and the potential of SAAS to reduce the incidence of postoperative dysphagia was not proven. No other complications were observed in this study. In the surgical treatment of three-level CSM, PCC is superior to SAAS in correction and maintenance of SA and avoiding cage subsidence, although the technique of ACDF with SAAS yielded encouraging clinical outcomes and high fusion rate. Copyright © 2015 Elsevier Inc. All rights reserved.

Feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content with changing postures.

PubMed

Nazari, Jalil; Pope, Malcolm H; Graveling, Richard A

2015-05-01

Opportunities to evaluate spinal loading in vivo are limited and a large majority of studies on the mechanical functions of the spine have been in vitro cadaveric studies and/or models based on many assumptions that are difficult to validate. The purpose of this study was to investigate the feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content measurements with changing postures. MRI studies were conducted on 25 healthy males with no history of low back pain (age 20-38). The L1 to S1 intradiscal levels were imaged in supine, sitting and standing postures using an upright 0.6 Tesla magnet, where a set of H2O: D2O7 phantoms were mounted on the back of the subjects. A calibration curve, provided from these phantoms, was applied to the absolute proton density image, yielding a pixel-by-pixel map of the water content of the NP. The NP at all levels showed a highly significant water loss (p<0.001) in sitting and standing postures compared with the supine posture. A trend towards higher levels of water was observed at all levels in the standing posture relative to sitting postures, however statistically significant differences were found only at L4-L5 and L5-S1 levels. This study demonstrates that variations in water content of the NP in different postures are in agreement with those determined from published invasive disc pressure measurements. The result of study demonstrates the feasibility of using MRI to determine the water content of the NP with changing postures and to use these data to evaluate spinal loading in these postures. This measurement method of water content by quantitative MR imaging could become a powerful tool for both clinical and ergonomic applications. The proposed methodology does not require invasive pressure measurement techniques. Copyright © 2015 Elsevier Inc. All rights reserved.

The nature of the Fe–graphene interface at the nanometer level

DOE PAGES

Cattelan, M.; Peng, G. W.; Cavaliere, E.; ...

2014-12-22

The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This paper reports a detailed investigation at the nanometer level of the Fe–graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, near edge X-ray absorption fine structure, scanning tunnelling microscopy and spin polarized density functional theory calculations. Quasi-free-standing graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Here, calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

RADIO FREQUENCY ATTENUATOR

DOEpatents

Giordano, S.

1963-11-12

A high peak power level r-f attenuator that is readily and easily insertable along a coaxial cable having an inner conductor and an outer annular conductor without breaking the ends thereof is presented. Spaced first and second flares in the outer conductor face each other with a slidable cylindrical outer conductor portion therebetween. Dielectric means, such as water, contact the cable between the flares to attenuate the radio-frequency energy received thereby. The cylindrical outer conductor portion is slidable to adjust the voltage standing wave ratio to a low level, and one of the flares is slidable to adjust the attenuation level. An integral dielectric container is also provided. (AFC)

Efficacy of variable density thinning and prescribed fire for restoring forest heterogeneity to mixed-conifer forest in the central Sierra Nevada, CA

Treesearch

Eric E. Knapp; Jamie M. Lydersen; Malcolm P. North; Brandon M. Collins

2017-01-01

Frequent-fire forests were historically characterized by lower tree density, a higher proportion of pine species, and greater within-stand spatial variability, compared to many contemporary forests where fire has been excluded. As a result, such forests are now increasingly unstable, prone to uncharacteristically severe wildfire or high levels of tree mortality in...

One-Hertz Waves at Mars: MAVEN Observations

NASA Astrophysics Data System (ADS)

Ruhunusiri, Suranga; Halekas, J. S.; Espley, J. R.; Eparvier, F.; Brain, D.; Mazelle, C.; Harada, Y.; DiBraccio, G. A.; Thiemann, E. M. B.; Larson, D. E.; Mitchell, D. L.; Jakosky, B. M.; Sulaiman, A. H.

2018-05-01

We perform a survey of 1-Hz waves at Mars utilizing Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft observations for a Martian year. We find that the 1-Hz wave occurrence rate shows an apparent variation caused by masking of the waves by background turbulence during the times when the background turbulence levels are high. To correct for this turbulence masking, we select waves that occur in time intervals where the background turbulence levels are low. We find that the extreme ultraviolet flux does not affect the wave occurrence rate significantly, suggesting that the newly born pickup ions originating in the Mars's exosphere contribute minimally to the 1-Hz wave generation. We find that the wave occurrence rates are higher for low Mach numbers and low beta values than for high Mach numbers and high beta values. Further, we find that a high percentage of 1-Hz waves satisfy the group-standing condition, which suggests that a high percentage of the waves seen as monochromatic waves in the spacecraft frame can be broadband waves in the solar wind frame that have group velocities nearly equal and opposite to the solar wind velocity. We infer that the wave occurrence rate trends with the Mach number and proton beta are a consequence of how the Mach numbers and beta values influence the wave generation and damping or how those parameters affect the group-standing condition. Finally, we find that the 1-Hz waves are equally likely to be found in both the quasi-parallel and the quasi-perpendicular foreshock regions.

Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests

PubMed Central

Fu, Xiaoli; Wang, Jianlei; Di, Yuebao; Wang, Huimin

2015-01-01

Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area) in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4%) than that at Datian (16.7%). This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer. PMID:26047358

Edaphic, salinity, and stand structural trends in chronosequences of native and non-native dominated riparian forests along the Colorado River, USA

USGS Publications Warehouse

Merritt, David M.; Shafroth, Patrick B.

2012-01-01

Tamarix spp. are introduced shrubs that have become among the most abundant woody plants growing along western North American rivers. We sought to empirically test the long-held belief that Tamarix actively displaces native species through elevating soil salinity via salt exudation. We measured chemical and physical attributes of soils (e.g., salinity, major cations and anions, texture), litter cover and depth, and stand structure along chronosequences dominated by Tamarix and those dominated by native riparian species (Populus or Salix) along the upper and lower Colorado River in Colorado and Arizona/California, USA. We tested four hypotheses: (1) the rate of salt accumulation in soils is faster in Tamarix-dominated stands than stands dominated by native species, (2) the concentration of salts in the soil is higher in mature stands dominated by Tamarix compared to native stands, (3) soil salinity is a function of Tamarix abundance, and (4) available nutrients are more concentrated in native-dominated stands compared to Tamarix-dominated stands. We found that salt concentration increases at a faster rate in Tamarix-dominated stands along the relatively free-flowing upper Colorado but not along the heavily-regulated lower Colorado. Concentrations of ions that are known to be preferentially exuded by Tamarix (e.g., B, Na, and Cl) were higher in Tamarix stands than in native stands. Soil salt concentrations in older Tamarix stands along the upper Colorado were sufficiently high to inhibit germination, establishment, or growth of some native species. On the lower Colorado, salinity was very high in all stands and is likely due to factors associated with floodplain development and the hydrologic effects of river regulation, such as reduced overbank flooding, evaporation of shallow ground water, higher salt concentrations in surface and ground water due to agricultural practices, and higher salt concentrations in fine-textured sediments derived from naturally saline parent material.

Differences in Fine-Root Biomass of Trees and Understory Vegetation among Stand Types in Subtropical Forests.

PubMed

Fu, Xiaoli; Wang, Jianlei; Di, Yuebao; Wang, Huimin

2015-01-01

Variation of total fine-root biomass among types of tree stands has previously been attributed to the characteristics of the stand layers. The effects of the understory vegetation on total fine-root biomass are less well studied. We examined the variation of total fine-root biomass in subtropical tree stands at two sites of Datian and Huitong in China. The two sites have similar humid monsoon climate but different soil organic carbon. One examination compared two categories of basal areas (high vs. low basal area) in stands of single species. A second examination compared single-species and mixed stands with comparable basal areas. Low basal area did not correlate with low total fine-root biomass in the single-species stands. The increase in seedling density but decrease in stem density for the low basal area stands at Datian and the quite similar stand structures for the basal-area contrast at Huitong helped in the lack of association between basal area and total fine-root biomass at the two sites, respectively. The mixed stands also did not yield higher total fine-root biomasses. In addition to the lack of niche complementarity between tree species, the differences in stem and seedling densities and the belowground competition between the tree and non-tree species also contributed to the similarity of the total fine-root biomasses in the mixed and single-species stands. Across stand types, the more fertile site Datian yielded higher tree, non-tree and total fine-root biomasses than Huitong. However, the contribution of non-tree fine-root biomass to the total fine-root biomass was higher at Huitong (29.4%) than that at Datian (16.7%). This study suggests that the variation of total fine-root biomass across stand types not only was associated with the characteristics of trees, but also may be highly dependent on the understory layer.

Effect of Experimentally Manipulated Fire Regimes on the Response of Forests to Drought

NASA Astrophysics Data System (ADS)

Refsland, T. K.; Knapp, B.; Fraterrigo, J.

2017-12-01

Climate change is expected to increase drought stress in many forests and alter fire regimes. Fire can reduce tree density and thus competition for limited water, but the effects of changing fire regimes on forest productivity during drought remain poorly understood. We measured the annual ring-widths of adult oak (Quercus spp.) trees in Mark Twain National Forest, Missouri USA that experienced unburned, annual or periodic (every 4 years) surface fire treatments from 1951 - 2015. Severe drought events were identified using the BILJOU water balance model. We determined the effect of fire treatment on stand-level annual growth rates as well as stand-level resistance and resilience to drought, defined as the drought-induced reduction in growth and post-drought recovery in growth, respectively. During favorable wet years, annual and periodic fire treatments reduced annual growth rates by approximately 10-15% relative to unburned controls (P < 0.001). Stand-level growth rates declined 22-40% during drought events (P < 0.001), but fire-driven changes to stand basal area had no effect on the resistance or resilience of trees to drought. The decline in annual growth rates of burned stands during favorable wet years was likely caused by increased nitrogen (N) limitation in burned plots. After 60 years of treatment, burned plots experienced 30% declines in total soil N relative to unburned plots. Our finding that drought resistance and resilience were similar across all treatments suggest that fire-driven reductions in stand density may have negligible effects on soil moisture availability during drought. Our results highlight that climate-fire interactions can have important long-term effects on forest productivity.

Stand-level forest structure and avian habitat: Scale dependencies in predicting occurrence in a heterogeneous forest

USGS Publications Warehouse

Smith, K.M.; Keeton, W.S.; Donovan, T.M.; Mitchell, B.

2008-01-01

We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern. Copyright ?? 2008 by the Society of American Foresters.

Metabolic syndrome in people with a long-standing spinal cord injury: associations with physical activity and capacity.

PubMed

de Groot, Sonja; Adriaansen, Jacinthe J; Tepper, Marga; Snoek, Govert J; van der Woude, Lucas H V; Post, Marcel W M

2016-11-01

This study investigated (i) the prevalence of the metabolic syndrome (MetS) in people with a long-standing spinal cord injury (SCI); (ii) whether personal or lesion characteristics are determinants of the MetS; and (iii) the association with physical activity or peak aerobic capacity on the MetS. In a cross-sectional study, persons with SCI (N = 223; time since injury of ≥10 years) were tested. The individual components of the MetS were assessed together with the physical activity measured by the Physical Activity Scale for Individuals with Physical Disabilities (PASIPD), while peak aerobic capacity was tested during a graded wheelchair exercise test on a treadmill. Thirty-nine percent of the participants had MetS. In a multivariate logistic regression analyses and after performing a backward regression analysis, only age and education were significant determinants of the MetS. A 10-year increase in age leads to a 1.5 times more chance to have the MetS. Furthermore, people with a low education will multiply the relative risk of MetS compared with people with high education by almost 2. With and without correcting for confounders, no significant relationship was found between PASIPD or peak aerobic capacity and the MetS. It can be concluded that the prevalence of the MetS is high (39%) in people with a long-standing SCI but is comparable to the general Dutch population. Older people and those with a lower education level are most at risk for the MetS. Physical activity and peak aerobic fitness were not related to the MetS in this group with a long-standing SCI.

Increasing fire severity, alternate successional trajectories, and the carbon balance of Alaskan boreal forests

NASA Astrophysics Data System (ADS)

Mack, M. C.; Alexander, H. D.; Jean, M.; Melvin, A. M.; Johnstone, J. F.

2016-12-01

Climate-sensitive disturbances, such as wildfire, can feed back positively to climate warming via the carbon (C) cycle if C released by disturbance is not replaced over post-fire succession. In boreal forests, burning of carbon in deep organic soils is not only an important determinate of ecosystem element balance over the disturbance cycle, but also sets the conditions that control plant recruitment, species dominance and successional trajectory. Species dominance, in turn, has the potential to exert strong control over the plant-soil-microbial feedbacks that determine C and nutrient coupling, C storage, and ultimately, replacement of combusted C. We examined the consequences of increasing fire severity for C balance and C and nitrogen (N) coupling in Alaskan boreal forests. We estimated combustion losses in 90 black spruce (conifer) stands that burned in 2004. Over the next decade, we followed natural tree seedling establishment in these stands and used seedling species dominance identify conifer versus deciduous successional trajectories. We assembled data from 120 stands that varied in time after fire and successional trajectory, and estimated C and N dynamics across 150 years of post-fire succession for each trajectory. Conifer stands that burned with high severity transitioned to deciduous tree dominance after fire. These stands had smaller ecosystem pools of C and N before fire, lost a larger proportion of these pools during the fire, and began succession with smaller residual pools than stands that returned to conifer dominance after fire. Over secondary succession, deciduous stands accumulated about 10 times more carbon in aboveground biomass than conifer stands. Belowground biomass and soil carbon accumulation, by contrast, was about three times higher in the black spruce stands than in deciduous stands. As a result, net ecosystem C accumulation over the 100 year inter-fire interval was three times higher in deciduous stands than in coniferous stands. Nitrogen accumulation did not differ between the trajectories; high C:N ratio biomass accumulation in deciduous stands balanced low C:N ratio soil organic matter accumulation in conifer stands. The timing of N accumulation, however, differed substantially, supporting the idea that deciduous stands mine N from degrading permafrost after fire.

Associations of occupational standing with musculoskeletal symptoms: a systematic review with meta-analysis.

PubMed

Coenen, Pieter; Willenberg, Lisa; Parry, Sharon; Shi, Joyce W; Romero, Lorena; Blackwood, Diana M; Maher, Christopher G; Healy, Genevieve N; Dunstan, David W; Straker, Leon M

2018-02-01

Given the high exposure to occupational standing in specific occupations, and recent initiatives to encourage intermittent standing among white-collar workers, a better understanding of the potential health consequences of occupational standing is required. We aimed to review and quantify the epidemiological evidence on associations of occupational standing with musculoskeletal symptoms. A systematic review was performed. Data from included articles were extracted and described, and meta-analyses conducted when data were sufficiently homogeneous. Electronic databases were systematically searched. Peer-reviewed articles on occupational standing and musculoskeletal symptoms from epidemiological studies were identified. Of the 11 750 articles screened, 50 articles reporting 49 studies were included (45 cross-sectional and 5 longitudinal; n=88 158 participants) describing the associations of occupational standing with musculoskeletal symptoms, including low-back (39 articles), lower extremity (14 articles) and upper extremity (18 articles) symptoms. In the meta-analysis, 'substantial' (>4 hours/workday) occupational standing was associated with the occurrence of low-back symptoms (pooled OR (95% CI) 1.31 (1.10 to 1.56)). Evidence on lower and upper extremity symptoms was too heterogeneous for meta-analyses. The majority of included studies reported statistically significant detrimental associations of occupational standing with lower extremity, but not with upper extremity symptoms. The evidence suggests that substantial occupational standing is associated with the occurrence of low-back and (inconclusively) lower extremity symptoms, but there may not be such an association with upper extremity symptoms. However, these conclusions are tentative as only limited evidence was found from high-quality, longitudinal studies with fully adjusted models using objective measures of standing. 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/.

Validity of linear encoder measurement of sit-to-stand performance power in older people.

PubMed

Lindemann, U; Farahmand, P; Klenk, J; Blatzonis, K; Becker, C

2015-09-01

To investigate construct validity of linear encoder measurement of sit-to-stand performance power in older people by showing associations with relevant functional performance and physiological parameters. Cross-sectional study. Movement laboratory of a geriatric rehabilitation clinic. Eighty-eight community-dwelling, cognitively unimpaired older women (mean age 78 years). Sit-to-stand performance power and leg power were assessed using a linear encoder and the Nottingham Power Rig, respectively. Gait speed was measured on an instrumented walkway. Maximum quadriceps and hand grip strength were assessed using dynamometers. Mid-thigh muscle cross-sectional area of both legs was measured using magnetic resonance imaging. Associations of sit-to-stand performance power with power assessed by the Nottingham Power Rig, maximum gait speed and muscle cross-sectional area were r=0.646, r=0.536 and r=0.514, respectively. A linear regression model explained 50% of the variance in sit-to-stand performance power including muscle cross-sectional area (p=0.001), maximum gait speed (p=0.002), and power assessed by the Nottingham Power Rig (p=0.006). Construct validity of linear encoder measurement of sit-to-stand power was shown at functional level and morphological level for older women. This measure could be used in routine clinical practice as well as in large-scale studies. DRKS00003622. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Disparate cardio-cerebral vascular modulation during standing in multiple system atrophy and Parkinson disease.

PubMed

Xu, Wei-Hai; Wang, Han; Wang, Bo; Niu, Fu-Sheng; Gao, Shan; Cui, Li-Ying

2009-01-15

The dynamic variance of cerebral blood flow velocity (CBFV), monitored by transcranial doppler (TCD), can reveal the integrated effects of cardio-cerebral vascular autoregulation. We investigated the characteristics of CBFV curve during active standing in multiple system atrophy (MSA), Parkinson's disease (PD) and healthy volunteers. The CBFV curve of middle cerebral arteries was recorded using TCD in 22 patients with probable MSA; 20 PD patients and 20 volunteers matched for age. All individuals started in a supine posture, followed by abrupt standing for 2 min before returning to supine. The features of CBFV curve were compared among the groups. In the healthy volunteers, the CBFV decreased following standing up but quickly rebounded and reached the same or greater level as the supine baseline. Afterwards, the CBFV decreased abruptly to a sustained level, lower than the supine baseline, forming a spike wave that appeared in CBFV curve. This spike wave was present in 5/22 of MSA, significantly less than PD patients (18/20) and volunteers (20/20) (P<0.001). The CBFV decrease after standing showed no significant difference between MSA than PD (9+/-7 vs. 6+/-3 cm/s, P=0.163). The different pattern of CBFV curves during active standing suggests MSA may possess cardio-cerebral vascular modulation different from PD. The clinical value of the CBFV curve in differentiating MSA from PD needs further investigation.

Test Stand at the Rocket Engine Test Facility

NASA Image and Video Library

1973-02-21

The thrust stand in the Rocket Engine Test Facility at the National Aeronautics and Space Administration (NASA) Lewis Research Center in Cleveland, Ohio. The Rocket Engine Test Facility was constructed in the mid-1950s to expand upon the smaller test cells built a decade before at the Rocket Laboratory. The $2.5-million Rocket Engine Test Facility could test larger hydrogen-fluorine and hydrogen-oxygen rocket thrust chambers with thrust levels up to 20,000 pounds. Test Stand A, seen in this photograph, was designed to fire vertically mounted rocket engines downward. The exhaust passed through an exhaust gas scrubber and muffler before being vented into the atmosphere. Lewis researchers in the early 1970s used the Rocket Engine Test Facility to perform basic research that could be utilized by designers of the Space Shuttle Main Engines. A new electronic ignition system and timer were installed at the facility for these tests. Lewis researchers demonstrated the benefits of ceramic thermal coatings for the engine’s thrust chamber and determined the optimal composite material for the coatings. They compared the thermal-coated thrust chamber to traditional unlined high-temperature thrust chambers. There were more than 17,000 different configurations tested on this stand between 1973 and 1976. The Rocket Engine Test Facility was later designated a National Historic Landmark for its role in the development of liquid hydrogen as a propellant.

Laser damage of free-standing nanometer membranes

NASA Astrophysics Data System (ADS)

Morimoto, Yuya; Roland, Iännis; Rennesson, Stéphanie; Semond, Fabrice; Boucaud, Philippe; Baum, Peter

2017-12-01

Many high-field/attosecond and ultrafast electron diffraction/microscopy experiments on condensed matter require samples in the form of free-standing membranes with nanometer thickness. Here, we report the measurement of the laser-induced damage threshold of 11 different free-standing nanometer-thin membranes of metallic, semiconducting, and insulating materials for 1-ps, 1030-nm laser pulses at 50 kHz repetition rate. We find a laser damage threshold that is very similar to each corresponding bulk material. The measurements also reveal a band gap dependence of the damage threshold as a consequence of different ionization rates. These results establish the suitability of free-standing nanometer membranes for high-field pump-probe experiments.

Around Marshall

NASA Image and Video Library

1962-10-26

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This construction photo, taken October 26, 1962, depicts a view of the Block House tunnel opening.

Around Marshall

NASA Image and Video Library

1962-08-17

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This construction photo taken August 17, 1962 depicts a back side view of the Block House.

Around Marshall

NASA Image and Video Library

1962-11-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This construction photo, taken November 15, 1962, depicts a view of the Block House.

Around Marshall

NASA Image and Video Library

1962-01-23

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This photo, taken January 23, 1962, shows the excavation of the Block House site.

Around Marshall

NASA Image and Video Library

1962-06-13

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. Construction of the tunnel is depicted in this photo taken June 13, 1962.

Around Marshall

NASA Image and Video Library

1962-02-02

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This photo, taken February 2, 1962, shows the excavation of the Block House site.

Effects of sitting versus standing and scanner type on cashiers.

PubMed

Lehman, K R; Psihogios, J P; Meulenbroek, R G

2001-06-10

In the retail supermarket industry where cashiers perform repetitive, light manual material-handling tasks when scanning and handling products, reports of musculoskeletal disorders and discomfort are high. Ergonomics tradeoffs exist between sitting and standing postures, which are further confounded by the checkstand design and point-of-sale technology, such as the scanner. A laboratory experiment study was conducted to understand the effects of working position (sitting versus standing) and scanner type (bi-optic versus single window) on muscle activity, upper limb and spinal posture, and subjective preference of cashiers. Ten cashiers from a Dutch retailer participated in the study. Cashiers exhibited lower muscle activity in the neck and shoulders when standing and using a bi-optic scanner. Shoulder abduction was also less for standing conditions. In addition, all cashiers preferred using the bi-optic scanner with mixed preferences for sitting (n = 6) and standing (n = 4). Static loading of the muscles was relatively high compared with benchmarks, suggesting that during the task of scanning, cashiers may not have adequate recovery time to prevent fatigue. It is recommended that retailers integrate bi-optic scanners into standing checkstands to minimize postural stress, fatigue and discomfort in cashiers.

Stand development and silviculture in bottomland hardwoods

Treesearch

J. Steven Meadows

1993-01-01

Silviculture for the production of high-quality timber in southern bottomland hardwood forests involves the application of environmentally sound practices in order to enhance the growth and quality of both individual trees and stands. To accomplish this purpose, silvicultural practices are typically used to regulate stand density, species composition, and stem quality...

Effects of thinning intensities on transpiration and productivity of 50-year-old Pinus koraeinsis stands

NASA Astrophysics Data System (ADS)

Park, Juhan; Kim, Taekyu; Moon, Minkyu; Cho, Sungsik; Ryu, Daun; Kim, Hyun Seok

2015-04-01

This study investigated the effects of thinning intensities on stand transpiration and productivity of 50-year-old Korean pine forests for two years. Forest thinning, which removes some fraction of trees from stand, is widely conducted for reducing competition between remaining trees, improving tree productivity, reducing the risk of natural fire, and thus maintaining healthy forest. Forest thinning alters the microclimatic conditions such as radiation distribution within canopy, vapor pressure deficit, and amount of available soil water. These changes influence on the tree water use, and related productivity. Thinning was conducted on March, 2012 with two intensities (Control, Light-thinning (20%), and Heavy-thinning (40% of tree density)). Transpiration was estimated from sap flux density, which was measured with Granier-type thermal dissipation sensors. Tree diameter growth was measured with dendrometer, and converted to tree productivity using allometric equations developed specifically in our study sites. The climatic conditions showed little differences between two years. During the first growing season after thinning, stand transpiration was ca. 20% and 42% lower on light-thinning and heavy-thinning stand, respectively, even though sap flux density were higher in thinned stand. The difference in stand transpiration among treatments showed seasonal trends, so it was larger on summer when soil moisture was abundant due to monsoon, but was diminished on spring and autumn when soil moisture was limited. Tree-level productivity increased ca. 8% and 21% on light-thinning and heavy thinning stand, respectively. However, stand net primary production was ca. 20% lower on light-thinning stand, and ca. 31% on heavy-thinning stand. As a result, water use efficiency increased only in heavy-thinning stand. During the second growing season after thinning, stand transpiration was ca. 19% lower on light-thinning stand, and ca. 37% lower on heavy-thinning stand. The reduction of stand transpiration difference in heavy-thinning stand was caused mainly by increase in sap flux density. Trees in thinned stand showed higher productivity, but the magnitude was ca. 4% on light-thinning stand, and ca. 27% on heavy-thinning stand. Stand net primary production was ca. 23% lower on light-thinning stand, and ca. 28% on heavy-thinning stand. As a result, heavy-thinning stand showed highest water use efficiency. These results indicate that there are differences in biological reactions with thinning intensities.

Model and algorithmic framework for detection and correction of cognitive errors.

PubMed

Feki, Mohamed Ali; Biswas, Jit; Tolstikov, Andrei

2009-01-01

This paper outlines an approach that we are taking for elder-care applications in the smart home, involving cognitive errors and their compensation. Our approach involves high level modeling of daily activities of the elderly by breaking down these activities into smaller units, which can then be automatically recognized at a low level by collections of sensors placed in the homes of the elderly. This separation allows us to employ plan recognition algorithms and systems at a high level, while developing stand-alone activity recognition algorithms and systems at a low level. It also allows the mixing and matching of multi-modality sensors of various kinds that go to support the same high level requirement. Currently our plan recognition algorithms are still at a conceptual stage, whereas a number of low level activity recognition algorithms and systems have been developed. Herein we present our model for plan recognition, providing a brief survey of the background literature. We also present some concrete results that we have achieved for activity recognition, emphasizing how these results are incorporated into the overall plan recognition system.

Prevalence and correlates of antibiotic sharing in the Philippines: antibiotic misconceptions and community-level access to non-medical sources of antibiotics.

PubMed

Barber, Daniel A; Casquejo, Efren; Ybañez, Purita L; Pinote, Magdaleno T; Casquejo, Luz; Pinote, Lucia S; Estorgio, Magdalena; Young, April M

2017-05-01

To identify sociodemographic, knowledge and attitudinal correlates to antibiotic sharing among a community-based sample of adults (age 18 and older) in a low-income setting of the Philippines and to explore community-level data on informal antibiotic distribution in roadside stands (i.e., sari-sari stands). Participants (n = 307) completed self-administered surveys. Correlates to antibiotic sharing were assessed using logistic regression with Firth's bias-adjusted estimates. Study staff also visited 106 roadside stands and collected data on availability and characteristics of antibiotics in the stands. 78% had shared antibiotics in their lifetime, most often with family members. In multivariable analysis, agreement with the belief that it is safe to prematurely stop an antibiotic course (OR: 2.8, CI: 1.3-5.8) and concerns about antibiotic side effects (OR: 2.1, CI: 1.1-4.4) were significantly associated with increased odds of reported antibiotic sharing. Antibiotic sharing was not associated with sociodemographic characteristics or antibiotic knowledge. Antibiotics were widely available in 60% of sampled sari-sari stands, in which 59% of antibiotics were missing expiration dates. Amoxicillin and cephalexin were the most commonly available antibiotics for sale at the stands (60% and 21%, respectively). Antibiotic sharing was common and was associated with misconceptions about proper antibiotic use. Antibiotics were widely available in sari-sari stands, and usually without expiration information. This study suggests that multipronged and locally tailored approaches to curbing informal antibiotic access are needed in the Philippines and similar Southeast-Asian countries. © 2017 John Wiley & Sons Ltd.

MRI in France: the French paradox.

PubMed

Lavayssière, R; Cabée, A E

2001-04-01

Although France is a modern, developed country, which spends nearly 10% of the gross national product on healthcare and has a highly praised level of medicine, the number of modern imaging scanners, such as CT (595), MRI (182), and PET (5), is quite low when compared to other European countries. Politics and a long-standing tradition of centralization are prominent among reasons for such an underdevelopment. This situation has resulted in another French paradox not linked to wine consumption. The French life expectancy is very high, but the number of imaging equipment is very low.

Liana infestation impacts tree growth in a lowland tropical moist forest

NASA Astrophysics Data System (ADS)

van der Heijden, G. M. F.; Phillips, O. L.

2009-03-01

Stand-level estimates of the effect of lianas on tree growth in mature tropical forests are needed to evaluate the functional impact of lianas and their potential to affect the ability of tropical forests to sequester carbon, but these are currently lacking. Using data collected on tree growth rates, local growing conditions and liana competition in five permanent sampling plots in Amazonian Peru, we present the first such estimates of the effect of lianas on above-ground productivity of trees. By constructing a multi-level linear mixed effect model to predict individual tree diameter growth model using individual tree growth conditions, we were able to estimate stand-level above-ground biomass (AGB) increment in the absence of lianas. We show that lianas, mainly by competing above-ground with trees, reduce tree annual above-ground stand-level biomass by ~10%, equivalent to 0.51 Mg dry weight ha-1 yr-1 or 0.25 Mg C ha-1 yr-1. AGB increment of lianas themselves was estimated to be 0.15 Mg dry weight ha-1 yr-1 or 0.07 Mg C ha-1 yr-1, thus only compensating ~29% of the liana-induced reduction in stand-level AGB increment. Increasing liana pressure on tropical forests may therefore not only reduce their carbon storage capacity, by indirectly promoting tree species with low-density wood, but also their rate of carbon uptake, with potential consequences for the rate of increase in atmospheric carbon dioxide.

Standing wave design and experimental validation of a tandem simulated moving bed process for insulin purification.

PubMed

Xie, Yi; Mun, Sungyong; Kim, Jinhyun; Wang, Nien-Hwa Linda

2002-01-01

A tandem simulated moving bed (SMB) process for insulin purification has been proposed and validated experimentally. The mixture to be separated consists of insulin, high molecular weight proteins, and zinc chloride. A systematic approach based on the standing wave design, rate model simulations, and experiments was used to develop this multicomponent separation process. The standing wave design was applied to specify the SMB operating conditions of a lab-scale unit with 10 columns. The design was validated with rate model simulations prior to experiments. The experimental results show 99.9% purity and 99% yield, which closely agree with the model predictions and the standing wave design targets. The agreement proves that the standing wave design can ensure high purity and high yield for the tandem SMB process. Compared to a conventional batch SEC process, the tandem SMB has 10% higher yield, 400% higher throughput, and 72% lower eluant consumption. In contrast, a design that ignores the effects of mass transfer and nonideal flow cannot meet the purity requirement and gives less than 96% yield.

Acute Cutaneous Microvascular Flow Responses to Whole-Body Tilting in Humans

NASA Technical Reports Server (NTRS)

Breit, Gregory A.; Watenpaugh, Donald E.; Ballard, Richard E.; Hargens, Alan R.

1993-01-01

The transition from upright to head-down tilt (HDT) posture in humans increases blood pressure superior to the heart and decreases pressure inferior to the heart. Consequently, above heart level, myogenic arteriolar tone probably increases with HDT, in opposition to the withdrawal of baroreceptor-mediated sympathetic tone. We hypothesized that due to antagonism between central and local controls, the response of the facial cutaneous micro- circulation to acute postural change will be weaker than that in the leg, where these two mechanisms reinforce each other. Cutaneous microvascular flow was measured by laser Doppler flowmetry simultaneously at the shin and the neck of 7 male and 3 female subjects. Subjects underwent a stepwise tilt protocol from standing control to 54 deg head-up tilt (HUT), 30 deg, 12 deg, 0 deg, -6 deg (HDT), -12 deg, -6 deg, 0 deg, 12 deg, 30 deg, 54 deg, and standing, for 30-sec periods with 10-sec transitions between postures. Flows at the shin and the neck increased significantly (P < 0.05) from standing baseline to 12 deg HUT (252 +/- 55 and 126 +/- 9% (bar-X +/- SE) of baseline, respectively). From 12 deg to -12 deg tilt, flows continued to increase at the shin (509 +/- 71% of baseline) but decreased at the neck to baseline levels (100 +/- 15% of baseline). Cutaneous microvascular flow recovered at both sites during the return to standing posture with significant hysteresis. Flow increases from standing to near-supine posture are attributed at both sites to baroreceptor-mediated vasodilation. The great dissimilarity in flow response magnitudes at the two measurement sites may be indicative of central/local regulatory antagonism above heart level and reinforcement below heart level.

Acute Cutaneous Microvascular Flow Responses to Whole-Body Tilting in Humans

NASA Technical Reports Server (NTRS)

Breit, Gregory A.; Watenpaugh, Donald E.; Ballard, Richard E.; Hargens, Alan R.

1993-01-01

The transition from upright to head-down tilt (HDT) posture in humans increases blood pressure superior to the heart and decreases pressure inferior to the heart. Consequently, above heart level, myogenic arteriolar tone probably increases with HDT, in opposition to the withdrawal of baroreceptor-mediated sympathetic tone. We hypothesized that due to antagonism between central and local controls, the response of the facial cutaneous microcirculation to acute postural change will be weaker than that in the leg, where these two mechanisms reinforce each other. Cutaneous microvascular flow was measured by laser Doppler flowmetry simultaneously at the shin and the neck of 7 male and 3 female subjects. Subjects underwent a stepwise tilt protocol from standing control to 54 deg head-up tilt (HUT), 30 deg, 12 deg, O deg, -6 deg (HDT), -12 deg, -6 deg, O deg, 12 deg, 30 deg, 54 deg, and standing, for 30-sec periods with 10-sec transitions between postures. Flows at the shin and the neck increased significantly (P less than 0.05) from standing baseline to 12 deg HUT (252 +/- 55 and 126 +/- 9% (bar X +/- SE) of baseline, respectively). From 12 deg to -12 deg tilt, flows continued to increase at the shin (509 +/- 71% of baseline) but decreased at the neck to baseline levels (100 +/- 15% of baseline). Cutaneous microvascular flow recovered at both sites during the return to standing posture with significant hysteresis. Flow increases from standing to near-supine posture are attributed at both sites to baroreceptor-mediated vasodilation. The great dissimilarity in flow response magnitudes at the two measurement sites may be indicative of central/local regulatory antagonism above heart level and reinforcement below heart level.

The effect of the X-Stop implantation on intervertebral foramen, segmental spinal canal length and disc space in elderly patients with lumbar spinal stenosis.

PubMed

Wan, Zongmiao; Wang, Shaobai; Kozanek, Michal; Xia, Qun; Mansfield, Frederick L; Lü, Guohua; Wood, Kirkham B; Li, Guoan

2012-03-01

To evaluate the biomechanical effect of the X-Stop device on the intervertebral foramen (IVF) and segmental spinal canal length (SSCL), as well as the intervertebral disc space at the implanted and the adjacent segments in patients with lumbar spinal stenosis (LSS). Eight elderly patients with LSS, scheduled for X-stop implantation, were CT or MRI scanned to construct 3D vertebral models (L2-S1). Before and after the surgery, each patient was also imaged using a dual-fluoroscopic image system during weight-bearing standing and maximum extension-flexion. The positions of the vertebrae were then determined using an established 2D-3D model matching method. The data revealed that the postoperative IVF area was significantly increased by 32.9% (or 32 mm2) (p<0.05) and the IVF width was increased by 24.4% (or 1.1 mm, p=0.06) during extension, but with minimal change in standing and flexion. The IVF heights were significantly (p<0.05) increased at standing by 1.2 mm and extension by 1.8 mm, but not at flexion. The SSCL were significantly (p<0.05) increased at extension by 1.2 mm, but not at standing and flexion. Anterior disc space of the implanted level was significantly decreased from 8.0 to 6.6 mm during standing. The X-Stop implantation efficiently enlarged the IVF area in the elderly patients with LSS at the operated level with little biomechanical effect immediately on the superior and inferior adjacent levels. However, it reduced the anterior disc space at the implanted level.

Nesting success of birds in different silvicultural treatments in southeastern U.S. Pine Forests

USGS Publications Warehouse

Barber, D.R.; Martin, T.E.; Melchiors, M.A.; Thill, R.E.; Wigley, T.B.

2001-01-01

We examined nesting success and levels of nest predation and cowbird parasitism among five different silvicultural treatments: regenerating (3-6 years old), mid-rotation (12-15 years old), and thinned (17-23 years old) pine plantations, single-tree selection, and late-rotation pine-hardwood stands in the Ouachita Mountains of Arkansas from 1993 to 1995. We monitored 1674 nests. Differences in daily mortality and daily predation rate among two or more treatments were found for 4 and 3 of 12 species, respectively. These differences were lost following Bonferroni adjustments, but thinned stands had higher levels of predation than single-tree selection stands when predation levels were averaged across species. Daily predation rates were positively correlated with the relative abundance of birds, suggesting that nest predators respond to prey availability (i.e., nests) in a density-dependent manner. The relative abundance of cowbirds differed among treatments, with the highest densities in regenerating, thinned, and single-tree selection stands. Field Sparrows (Spizella pusilla) and Yellow-breasted Chats (Icteria virens) experienced higher levels of parasitism in thinned than regenerating plantations, whereas White-eyed Vireos (Vireo griseus) experienced higher parasitism in regenerating plantations than in mid-rotation or thinned plantations. Several shrub-nesting and 1 ground-nesting species had lower nesting success in thinned and regenerating plantations than has been reported in previously published studies. Thus, some seral stages of even-aged management may provide low-quality nesting habitat for several early-successional bird species. In contrast, many species nesting in mid-rotation and single-tree selection stands had nesting success similar to or greater than that found in previous studies, suggesting that some silvicultural treatments, when embedded in a largely forested landscape, may provide suitable habitat for forest land birds without affecting their reproductive success.

Around Marshall

NASA Image and Video Library

1963-02-04

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. This photograph taken February 4, 1963, gives an impressive look at the Block House looking directly through the ever-growing four towers of the S-IC Test Stand.

Construction Progress of the S-IC Test Stand Complex Bunker House

NASA Technical Reports Server (NTRS)

1963-01-01

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army's Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC stand, additional related facilities were built during this time frame. Built to the east of the S-IC stand, the block house served as the control room. To the south of the blockhouse was a newly constructed pump house used for delivering water to the S-IC stand during testing. North of the massive test stand, the F-1 Engine test stand was built for testing a single F-1 engine. Just southeast of the S-IC stand a concrete bunker house was constructed. The bunker housed an emergency crew clad in fire proof gear, who were close at hand should any emergencies arise during testing. This photo of the completed bunker house was taken on May 7, 1963.

Using Sit-Stand Workstations to Decrease Sedentary Time in Office Workers: A Randomized Crossover Trial

PubMed Central

Dutta, Nirjhar; Koepp, Gabriel A.; Stovitz, Steven D.; Levine, James A.; Pereira, Mark A.

2014-01-01

Objective: This study was conducted to determine whether installation of sit-stand desks (SSDs) could lead to decreased sitting time during the workday among sedentary office workers. Methods: A randomized cross-over trial was conducted from January to April, 2012 at a business in Minneapolis. 28 (nine men, 26 full-time) sedentary office workers took part in a 4 week intervention period which included the use of SSDs to gradually replace 50% of sitting time with standing during the workday. Physical activity was the primary outcome. Mood, energy level, fatigue, appetite, dietary intake, and productivity were explored as secondary outcomes. Results: The intervention reduced sitting time at work by 21% (95% CI 18%–25%) and sedentary time by 4.8 min/work-hr (95% CI 4.1–5.4 min/work-hr). For a 40 h work-week, this translates into replacement of 8 h of sitting time with standing and sedentary time being reduced by 3.2 h. Activity level during non-work hours did not change. The intervention also increased overall sense of well-being, energy, decreased fatigue, had no impact on productivity, and reduced appetite and dietary intake. The workstations were popular with the participants. Conclusion: The SSD intervention was successful in increasing work-time activity level, without changing activity level during non-work hours. PMID:24968210

Periodic upright posture negates the suppression of neuroendocrine response to head down bedrest

NASA Technical Reports Server (NTRS)

Wade, C. E.; Vernikos, J.; Evans, J.; Ohara, D.

1992-01-01

Head down bedrest (HDT) decreases plasma neurohormone levels, attaining a nadir within four hours. The present study evaluates the effect of periodic standing or exercises (+G(z)) on this acute suppression of plasma neurohormones. Methods: Nine male subjects (mean plus or minus SE age 37 plus or minus 2 yr; height 182 plus or minus 2 cm; weight 83 plus or minus 3 kg) were admitted to the Human Research Facility on three occasions separated by one month. Subjects were assigned to head down tilt (minus 6 degrees) or 15-minutes of standing or moderate exercise at the end of each hour. Initially during an ambulatory period, subjects were placed in a supine position for 45-min and a control blood sample obtained. The next day following 4 hours of HDT with or without standing or exercise a blood sample was taken 45-min (3 3/4 hours into HDT) after the preceding stand or exercise. Blood was withdrawn and all plasma samples frozen for determination of neurohormone levels within the same assay. Plasma aldosterone, Plasma Renin Activity (PRA) vasopressin (AVP) and cortisol levels were measured by radioimmunoassay. Norepinephrine (NE) and epinephrine (E) levels were measured by electrochemical detection following HPLC. Values were compared by ANOVA, P less than 0.05. Results: Control levels following 45-min supine were not different between treatments. HDT suppressed plasma aldosterone (13.9 plus or minus 3.7 to 6.6 plus or minus 0.7 ng/dl) and NE levels (299 plus or minus 35 to 217 plus or minus 23 pg/dl), E (69 plus or minus 15 to 65 plus or minus 21 pg/ml), and PRA (0.64 plus or minus 0.13 to 0.58 plus or minus 0.17 ngAl/m/hr) were not significantly altered. Standing or exercise negated the decrease in aldosterone and NE levels due to HDT. Conclusions: Periodic upright posture (+G(z)) with or without exercise for 15-min out of each hour negates the acute suppression of aldosterone and NE associated with HDT.

Excess growing-season water limits lowland black spruce productivity

NASA Astrophysics Data System (ADS)

Dymond, S.; Kolka, R. K.; Bolstad, P. V.; Gill, K.; Curzon, M.; D'Amato, A. W.

2015-12-01

The annual growth of many tree species is limited by water availability, with growth increasing as water becomes less scarce. In lowland bogs of northern Minnesota, however, black spruce (Picea mariana) is often exposed to excess water via high water table elevations. These trees grow in thick deposits of organic mucky peat and often have shallow rooting systems to avoid the complete submersion of roots in water. While it is generally believed that black spruce decrease growth rates with rising water table elevations, this hypothesis has not been tested in situ. We used a unique, 50-year record of daily bog water table elevations at the Marcell Experimental Forest (MEF) in northern Minnesota to investigate the relationship between climate and black spruce productivity. Nine 1/20th ha circular plots were established in five different bogs and tree height, diameter-at-breast-height (DBH), and crown class were recorded. Additionally, two perpendicular cores were collected on all trees greater than 10 cm diameter-at-breast-height. Tree cores were sanded, mounted, cross-dated, and de-trended according to standard dendrochronological procedures. Ring width measurements were correlated with precipitation, temperature, and water table elevation using package BootRes in R to determine the climatic variables most associated with stand level productivity. Across the different plots, we found that early growing season water table elevation (May and June) was negatively correlated with both individual and stand-level black spruce growth (p < 0.01), while growth was positively correlated with March temperatures (p < 0.01). No significant relationships existed between black spruce growth and monthly precipitation. If summer water table elevations in these peatland ecosystems rise as is anticipated with more extreme precipitation events due to climate change, we could see an overall decrease in the stand level productivity of black spruce.

Design Difficulties in Stand Density Studies

Treesearch

Frank A. Bennett

1969-01-01

Designing unbiased stand density studies is difficult. An acceptable sample requires stratification of the plots of age, site, and density. When basal area, percent stocking, or Reineke's stand density index is used as the density measure, this stratification forces a high negative correlation between site and number of trees per acre. Mortality in trees per acre...

Effect of revised high-heeled shoes on foot pressure and static balance during standing.

PubMed

Bae, Young-Hyeon; Ko, Mansoo; Park, Young-Soul; Lee, Suk-Min

2015-04-01

[Purpose] The purpose of this study was to investigate the effects of revised high-heeled shoes on the foot pressure ratio and static balance during standing. [Subjects and Methods] A single-subject design was used, 15 healthy women wearing revised high-heeled shoes and general high-heeled shoes in a random order. The foot pressure ratio and static balance scores during standing were measured using a SpaceBalance 3D system. [Results] Forefoot and rearfoot pressures were significantly different between the 2 types of high-heeled shoes. Under the 3 conditions tested, the static balance score was higher for the revised high-heeled shoes than for the general high-heeled shoes, but this difference was not statistically significant. [Conclusion] Revised high-heeled shoes are preferable to general high-heeled shoes, as they result in normalization of normalized foot pressure and a positive effect on static balance.

Effect of revised high-heeled shoes on foot pressure and static balance during standing

PubMed Central

Bae, Young-Hyeon; Ko, Mansoo; Park, Young-Soul; Lee, Suk-Min

2015-01-01

[Purpose] The purpose of this study was to investigate the effects of revised high-heeled shoes on the foot pressure ratio and static balance during standing. [Subjects and Methods] A single-subject design was used, 15 healthy women wearing revised high-heeled shoes and general high-heeled shoes in a random order. The foot pressure ratio and static balance scores during standing were measured using a SpaceBalance 3D system. [Results] Forefoot and rearfoot pressures were significantly different between the 2 types of high-heeled shoes. Under the 3 conditions tested, the static balance score was higher for the revised high-heeled shoes than for the general high-heeled shoes, but this difference was not statistically significant. [Conclusion] Revised high-heeled shoes are preferable to general high-heeled shoes, as they result in normalization of normalized foot pressure and a positive effect on static balance. PMID:25995572

A structural equation model analysis of postfire plant diversity in California shrublands

USGS Publications Warehouse

Grace, J.B.; Keeley, J.E.

2006-01-01

This study investigates patterns of plant diversity following wildfires in fire-prone shrublands of California, seeks to understand those patterns in terms of both local and landscape factors, and considers the implications for fire management. Ninety study sites were established following extensive wildfires in 1993, and 1000-m2 plots were used to sample a variety of parameters. Data on community responses were collected for five years following fire. Structural equation modeling (SEM) was used to relate plant species richness to plant abundance, fire severity, abiotic conditions, within-plot heterogeneity, stand age, and position in the landscape. Temporal dynamics of average richness response was also modeled. Richness was highest in the first year following fire, indicating postfire enhancement of diversity. A general decline in richness over time was detected, with year-to-year variation attributable to annual variations in precipitation. Peak richness in the landscape was found where (1) plant abundance was moderately high, (2) within-plot heterogeneity was high, (3) soils were moderately low in nitrogen, high in sand content, and with high rock cover, (4) fire severity was low, and (5) stands were young prior to fire. Many of these characteristics were correlated with position in the landscape and associated conditions. We infer from the SEM results that postfire richness in this system is strongly influenced by local conditions and that these conditions are, in turn, predictably related to landscape-level conditions. For example, we observed that older stands of shrubs were characterized by more severe fires, which were associated with a low recovery of plant cover and low richness. These results may have implications for the use of prescribed fire in this system if these findings extrapolate to prescribed burns as we would expect. ?? 2006 by the Ecological Society of America.

The interplay of plant and animal disease in a changing landscape: the role of sudden aspen decline in moderating Sin Nombre virus prevalence in natural deer mouse populations.

PubMed

Lehmer, Erin M; Korb, Julie; Bombaci, Sara; McLean, Nellie; Ghachu, Joni; Hart, Lacey; Kelly, Ashley; Jara-Molinar, Edlin; O'Brien, Colleen; Wright, Kimberly

2012-06-01

We examined how climate-mediated forest dieback regulates zoonotic disease prevalence using the relationship between sudden aspen decline (SAD) and Sin Nombre virus (SNV) as a model system. We compared understory plant community structure, small mammal community composition, and SNV prevalence on 12 study sites within aspen forests experiencing levels of SAD ranging from <10.0% crown fade to >95.0% crown fade. Our results show that sites with the highest levels of SAD had reduced canopy cover, stand density, and basal area, and these differences were reflected by reductions in understory vegetation cover. Conversely, sites with the highest levels of SAD had greater understory standing biomass, suggesting that vegetation on these sites was highly clustered. Changes in forest and understory vegetation structure likely resulted in shifts in small mammal community composition across the SAD gradient, as we found reduced species diversity and higher densities of deer mice, the primary host for SNV, on sites with the highest levels of SAD. Sites with the highest levels of SAD also had significantly greater SNV prevalence compared to sites with lower levels of SAD, which is likely a result of their abundance of deer mice. Collectively, results of our research provide strong evidence to show SAD has considerable impacts on vegetation community structure, small mammal density and biodiversity and the prevalence of SNV.

The impact of sit-stand office workstations on worker discomfort and productivity: a review.

PubMed

Karakolis, Thomas; Callaghan, Jack P

2014-05-01

This review examines the effectiveness of sit-stand workstations at reducing worker discomfort without causing a decrease in productivity. Four databases were searched for studies on sit-stand workstations, and five selection criteria were used to identify appropriate articles. Fourteen articles were identified that met at least three of the five selection criteria. Seven of the identified studies reported either local, whole body or both local and whole body subjective discomfort scores. Six of these studies indicated implementing sit-stand workstations in an office environment led to lower levels of reported subjective discomfort (three of which were statistically significant). Therefore, this review concluded that sit-stand workstations are likely effective in reducing perceived discomfort. Eight of the identified studies reported a productivity outcome. Three of these studies reported an increase in productivity during sit-stand work, four reported no affect on productivity, and one reported mixed productivity results. Therefore, this review concluded that sit-stand workstations do not cause a decrease in productivity. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

The ontogeny of individual vs. stand-level responses to elevated CO[sub 2

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

Thomas, S.C.; Jasienski, M.; Bazzaz, F.A.

1994-06-01

Plant species appear to differ widely in terms of growth responses to elevated CO[sub 2]; however, most existing comparative data are limited to observations made early in the ontogeny on plants grown an isolated individuals. We examined growth responses to elevated CO[sub 2] in nine species of herbaceous plants, including three erect annuals (genera included Abutilon, Ambrosia, and Cassia) three grasses (Dactylis, Lolium, Panicum), and three rosette species (Plantago, Rumex, and Taraxacum), each grown as isolated individuals and as dense monocultures in ambient (350 ppm) and 2X ambient (700 ppm) CO[sub 2] atmospheres in a glasshouse over 5-6 mo. Soilmore » texture, depth, and nutrient conditions matched those of waste areas in western Massachusetts. On the basis of non-destructive estimates of leaf area index (LAI), all species exhibited large early growth responses to CO[sub 2], ranging up to 50-120%. However, later in stand ontogeny LAI consistently converged between CO[sub 2] treatments, eventually becoming lower at ambient than at elevated CO[sub 2] in most species. Final total biomass effects at the stand level were in the range of 0-10% enhancements, with no consistent differences among growth forms. Reproductive output was significantly reduced by elevated CO[sub 2] in several species, including some with very high early growth enhancements. Our results strongly suggest that CO[sub 2] effects on early growth of individual plants greatly overestimate longer term effects on species performance and net ecosystem carbon gain.« less

Aspen Ecology in Rocky Mountain National Park: Age Distribution, Genetics, and the Effects of Elk Herbivory

USGS Publications Warehouse

Zeigenfuss, Linda C.; Binkley, Dan; Tuskan, Gerald A.; Romme, William H.; Yin, Tongming; DiFazio, Stephen; Singer, Francis J.

2008-01-01

Lack of recruitment and canopy replacement of aspen (Populus tremuloides) stands that grow on the edges of grasslands on the low-elevation elk (Cervus elaphus) winter range of Rocky Mountain National Park (RMNP) in Colorado have been a cause of concern for more than 70 years. We used a combination of traditional dendrochronology and genetic techniques as well as measuring the characteristics of regenerating and nonregenerating stands on the elk winter range to determine when and under what conditions and estimated elk densities these stands established and through what mechanisms they may regenerate. The period from 1975 to 1995 at low elevation on the east side had 80-95 percent fewer aspen stems than would be expected based on the trend from 1855 through 1965. The age structure of aspen in the park indicates that the interacting effects of fires, elk population changes, and livestock grazing had more-or-less consistent effects on aspen from 1855 to 1965. The lack of a significant change in aspen numbers in recent decades in the higher elevation and west side parts of the park supports the idea that the extensive effects of elk browsing have been more important in reducing aspen numbers than other factors. The genetic variation of aspen populations in RMNP is high at the molecular level. We expected to find that most patches of aspen in the park were composed of a single clone of genetically identical trees, but in fact just 7 percent of measured aspen patches consisted of a single clone. A large frequency of polyploid (triploid and tetraploid) genotypes were found on the low elevation, east-side elk winter range. Nonregenerating aspen stands on the winter range had greater annual offtake, shorter saplings, and lower density of mid-height (1.5-2.5 m) saplings than regenerating stands. Overwinter elk browsing, however, did not appear to inhibit the leader length of aspen saplings. The winter range aspen stands of RMNP appear to be highly resilient in the face of very intense herbivory by elk and harsh environmental conditions. Conservation efforts through fencing protection and decreased elk browsing pressure are already being planned as part of the park's new elk management plan. If these efforts are undertaken, conditions that encourage stem recruitment to the tree canopy will likely result and the continued survival of these aspen stands will be enhanced.

Mapping burn severity, pine beetle infestation, and their interaction at the High Park Fire

NASA Astrophysics Data System (ADS)

Stone, Brandon

North America's western forests are experiencing wildfire and mountain pine beetle (MPB) disturbances that are unprecedented in the historic record, but it remains unclear whether and how MPB infestation influences post-infestation fire behavior. The 2012 High Park Fire burned in an area that's estimated to have begun a MPB outbreak cycle within five years before the wildfire, resulting in a landscape in which disturbance interactions can be studied. A first step in studying these interactions is mapping regions of beetle infestation and post-fire disturbance. We implemented an approach for mapping beetle infestation and burn severity using as source data three 5 m resolution RapidEye satellite images (two pre-fire, one post-fire). A two-tiered methodology was developed to overcome the spatial limitations of many classification approaches through explicit analyses at both pixel and plot level. Major land cover classes were photo-interpreted at the plot-level and their spectral signature used to classify 5 m images. A new image was generated at 25 m resolution by tabulating the fraction of coincident 5 m pixels in each cover class. The original photo interpretation was then used to train a second classification using as its source image the new 25 m image. Maps were validated using k-fold analysis of the original photo interpretation, field data collected immediately post-fire, and publicly available classifications. To investigate the influence of pre-fire beetle infestation on burn severity within the High Park Fire, we fit a log-linear model of conditional independence to our thematic maps after controlling for forest cover class and slope aspect. Our analysis revealed a high co-occurrence of severe burning and beetle infestation within high elevation lodgepole pine stands, but did not find statistically significant evidence that infected stands were more likely to burn severely than similar uninfected stands. Through an inspection of the year-to-year changes in the class fraction signatures of pixels classified as MPB infestation, we were able to observe increases in infection extent and intensity in the year before the fire. The resulting maps will help to increase our understanding of the process that contributed to the High Park Fire, and we believe that the novel classification approach will allow for improved characterization of forest disturbances.

Effects of a gravity gradient on human cardiovascular responses

NASA Technical Reports Server (NTRS)

Hastreiter, D.; Young, L. R.

1997-01-01

Eight subjects participated in one control and three rotation trials on a short-arm centrifuge such that the Gz levels at the feet were 0.5, 1.0, and 1.5 G. Trials consisted of 30 minutes of supine rest, 1 hour of rotation (or in the control, 30 additional minutes of rest and 30 minutes of standing), and a final 30-minute rest period. Measurements of heart rate, calf impedance, calf volume, and blood pressure support the findings that the highest G level is similar to standing and that the lower G levels fail to produce significant effects.

Electron mobility on the surface of liquid Helium: influence of surface level atoms and depopulation of lowest subbands

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

Grigoriev, P. D., E-mail: grigorev@itp.ac.ru; Dyugaev, A. M.; Lebedeva, E. V.

2008-02-15

The temperature dependence of electron mobility is examined. We calculate the contribution to the electron scattering rate from the surface level atoms (SLAs), proposed in [10]. This contribution is substantial at low temperatures T < 0.5, when the He vapor concentration is exponentially small. We also study the effect of depopulation of the lowest energy subband, which leads to an increase in the electron mobility at high temperature. The results explain certain long-standing discrepancies between the existing theory and experiment on electron mobility on the surface of liquid helium.

Universal computer test stand (recommended computer test requirements). [for space shuttle computer evaluation

NASA Technical Reports Server (NTRS)

1973-01-01

Techniques are considered which would be used to characterize areospace computers with the space shuttle application as end usage. The system level digital problems which have been encountered and documented are surveyed. From the large cross section of tests, an optimum set is recommended that has a high probability of discovering documented system level digital problems within laboratory environments. Defined is a baseline hardware, software system which is required as a laboratory tool to test aerospace computers. Hardware and software baselines and additions necessary to interface the UTE to aerospace computers for test purposes are outlined.

Foundational Security Principles for Medical Application Platforms* (Extended Abstract)

PubMed Central

Vasserman, Eugene Y.; Hatcliff, John

2014-01-01

We describe a preliminary set of security requirements for safe and secure next-generation medical systems, consisting of dynamically composable units, tied together through a real-time safety-critical middleware. We note that this requirement set is not the same for individual (stand-alone) devices or for electronic health record systems, and we must take care to define system-level requirements rather than security goals for components. The requirements themselves build on each other such that it is difficult or impossible to eliminate any one of the requirements and still achieve high-level security goals. PMID:25599096

Influence of stocking, site quality, stand age, low-severity canopy disturbance, and forest composition on sub-boreal aspen mixedwood carbon stocks

USGS Publications Warehouse

Reinikainen, Michael; D’Amato, Anthony W.; Bradford, John B.; Fraver, Shawn

2014-01-01

Low-severity canopy disturbance presumably influences forest carbon dynamics during the course of stand development, yet the topic has received relatively little attention. This is surprising because of the frequent occurrence of such events and the potential for both the severity and frequency of disturbances to increase as a result of climate change. We investigated the impacts of low-severity canopy disturbance and average insect defoliation on forest carbon stocks and rates of carbon sequestration in mature aspen mixedwood forests of varying stand age (ranging from 61 to 85 years), overstory composition, stocking level, and site quality. Stocking level and site quality positively affected the average annual aboveground tree carbon increment (CAAI), while stocking level, site quality, and stand age positively affected tree carbon stocks (CTREE) and total ecosystem carbon stocks (CTOTAL). Cumulative canopy disturbance (DIST) was reconstructed using dendroecological methods over a 29-year period. DIST was negatively and significantly related to soil carbon (CSOIL), and it was negatively, albeit marginally, related to CTOTAL. Minima in the annual aboveground carbon increment of trees (CAI) occurred at sites during defoliation of aspen (Populus tremuloides Michx.) by forest tent caterpillar (Malacosoma disstria Hubner), and minima were more extreme at sites dominated by trembling aspen than sites mixed with conifers. At sites defoliated by forest tent caterpillar in the early 2000s, increased sequestration by the softwood component (Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss) compensated for overall decreases in CAI by 17% on average. These results underscore the importance of accounting for low-severity canopy disturbance events when developing regional forest carbon models and argue for the restoration and maintenance of historically important conifer species within aspen mixedwoods to enhance stand-level resilience to disturbance agents and maintain site-level carbon stocks.

A Clinical Comparison of Anterior Cervical Plates Versus Stand-Alone Intervertebral Fusion Devices for Single-Level Anterior Cervical Discectomy and Fusion Procedures.

PubMed

Panchal, Ripul R; Kim, Kee D; Eastlack, Robert; Lopez, John; Clavenna, Andrew; Brooks, Daina M; Joshua, Gita

2017-03-01

To compare radiologic and clinical outcomes, including rates of dysphagia and dysphonia, using a no-profile stand-alone intervertebral spacer with integrated screw fixation versus an anterior cervical plate and spacer construct for single-level anterior cervical discectomy and fusion (ACDF) procedures. This multicenter, randomized, prospective study included 54 patients with degenerative disc disease requiring ACDF at a single level at C3-C7. Twenty-six patients underwent single-level ACDF with stand-alone spacers, and 28 with plate fixation and spacers. Analyses were based on comparison of perioperative outcomes, radiologic and clinical metrics, and incidence of dysphagia and/or dysphonia. Mean patient age was 48.8 ± 10.1years (53.7% female). No significant differences were observed between groups in operative time (101.8 ± 34.4 minutes, 114.4 ± 31.5 minutes), estimated blood loss (44.8 ± 76.5 mL, 82.5 ± 195.1 mL), or length of hospital stay (1.2 ± 0.6 days, 1.3 ± 0.6 days). Mean visual analog scale pain scores and Neck Disability Index scores improved significantly from preoperative to last follow-up (10.8 ± 2.6 months) in both groups (P < 0.05). Mean Voice Handicap Index and Eating Assessment Tool scores improved significantly from discharge to last follow-up in both groups (P < 0.05). From discharge to 6 months, the stand-alone spacers group consistently demonstrated greater improvement in Voice Handicap Index. Preoperative intervertebral disc and neuroforaminal heights increased significantly across treatment groups (P < 0.01), and no cases required surgical revision at index or adjacent levels. Anterior cervical discectomy and fusion with stand-alone spacers resulted in similar clinical and radiologic outcomes as compared with plate and spacers and may help minimize postoperative dysphonia. Copyright © 2016 Elsevier Inc. All rights reserved.

Introduction: Forest restoration in temperate and boreal zones

Treesearch

Emile Gardiner; Katrine Hahn; Magnus Löf

2003-01-01

The past decade has witnessed an acceleration of forest restoration activities around the globe. Afforestation of former agricultural land, rehabilitation of natural forest processes and structures at the stand and landscape levels, and conversion of single-species plantations to mixed-species stands are among the prominent types of restoration practices currently...

Restoration management in redwood forests degraded by sudden oak death

Treesearch

Richard C. Cobb; Peter Hartsough; Kerri Frangioso; Janet Klein; Mike Swezy; Andrea Williams; Carl Sanders; Susan J. Frankel; David M. Rizzo

2017-01-01

We describe the foundation, objectives, and initial results from a stand-level experiment focused on restoration of redwood (Sequoia sempervirens (D. Don) Endl.) forests impacted by sudden oak death (SOD), caused by Phytophthora ramorum. Our study stands were primed for heavy impacts by SOD. Extensive harvesting which ended...

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).

Code of Federal Regulations, 2014 CFR

2014-07-01

.... (stress grade) construction grade lumber or equivalent. (vi) All scaffold work levels 10 feet or higher... (towers). 1910.29 Section 1910.29 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND..., construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and...

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (stress grade) construction grade lumber or equivalent. (vi) All scaffold work levels 10 feet or higher... (towers). 1910.29 Section 1910.29 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND..., construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and...

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).

Code of Federal Regulations, 2012 CFR

2012-07-01

.... (stress grade) construction grade lumber or equivalent. (vi) All scaffold work levels 10 feet or higher... (towers). 1910.29 Section 1910.29 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND..., construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and...

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).

Code of Federal Regulations, 2013 CFR

2013-07-01

.... (stress grade) construction grade lumber or equivalent. (vi) All scaffold work levels 10 feet or higher... (towers). 1910.29 Section 1910.29 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND..., construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and...

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).

Code of Federal Regulations, 2011 CFR

2011-07-01

.... (stress grade) construction grade lumber or equivalent. (vi) All scaffold work levels 10 feet or higher... (towers). 1910.29 Section 1910.29 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND..., construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and...

Tree density and permafrost thaw depth influence water limitations on stomatal conductance in Siberian Arctic boreal forests

NASA Astrophysics Data System (ADS)

Kropp, H.; Loranty, M. M.; Natali, S.; Kholodov, A. L.; Alexander, H. D.; Zimov, N.

2017-12-01

Boreal forests may experience increased water stress under global climate change as rising air temperatures increase evaporative demand and decrease soil moisture. Increases in plant water stress can decrease stomatal conductance, and ultimately, decrease primary productivity. A large portion of boreal forests are located in Siberia, and are dominated by deciduous needleleaf trees, Larix spp. We investigated the variability and drivers of canopy stomatal conductance in upland Larix stands with different stand density that arose from differing fire severity. Our measurements focus on an open canopy stand with low tree density and deep permafrost thaw depth, and a closed canopy stand with high tree density and shallow permafrost thaw depth. We measured canopy stomatal conductance, soil moisture, and micrometeorological variables. Our results demonstrate that canopy stomatal conductance was significantly lower in the closed canopy stand with a significantly higher sensitivity to increases in atmospheric evaporative demand. Canopy stomatal conductance in both stands was tightly coupled to precipitation that occurred over the previous week; however, the closed canopy stand showed a significantly greater sensitivity to increases in precipitation compared to the open canopy stand. Differences in access to deep versus shallow soil moisture and the physical characteristics of the soil profile likely contribute to differences in sensitivity to precipitation between the two stands. Our results indicate that Larix primary productivity may be highly sensitive to changes in evaporative demand and soil moisture that can result of global climate change. However, the effect of increasing air temperatures and changes in precipitation will differ significantly depending on stand density, thaw depth, and the hydraulic characteristics of the soil profile.

Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon

USGS Publications Warehouse

Tappeiner, J. C.; Huffman, D.; Spies, T.; Bailey, John D.

1997-01-01

We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees in the old-growth stands were significantly greater than those in the young-growth stands. Growth rates in the old stands were comparable with those from long-term studies of young stands in which density is about 100-120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10 years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged period, and trees grew at low density with little self-thinning; in contrast, after timber harvest, young stands may develop with high density of trees with similar ages and considerable self-thinning. The results suggest that thinning may be needed in dense young stands where the management objective is to speed development of old-growth characteristics.

Conjunction of standing wave and resonance in asymmetric nanowires: a mechanism for thermal rectification and remote energy accumulation.

PubMed

Liu, Yue-Yang; Zhou, Wu-Xing; Chen, Ke-Qiu

2015-12-02

As an important way to control and manage heat transport, thermal rectification has become an elementary issue in the field of phononics and plays a key role in the designing of thermal devices. Here we investigate systematically the standing wave and the accompanying resonance process in asymmetric nanowires to understand the standing wave itself and its great effect on thermal rectification. Results show that the standing wave is sensitive to both the structural and thermal properties of the material, and its great effect on enhancing the thermal rectification is realized not only by the energy-localization nature of the standing wave, but also by the resonance-caused large amplitude and high energy of the standing wave.

Atmospheric CO2 mole fraction affects stand-scale carbon use efficiency of sunflower by stimulating respiration in light.

PubMed

Gong, Xiao Ying; Schäufele, Rudi; Lehmeier, Christoph Andreas; Tcherkez, Guillaume; Schnyder, Hans

2017-03-01

Plant carbon-use-efficiency (CUE), a key parameter in carbon cycle and plant growth models, quantifies the fraction of fixed carbon that is converted into net primary production rather than respired. CUE has not been directly measured, partly because of the difficulty of measuring respiration in light. Here, we explore if CUE is affected by atmospheric CO 2 . Sunflower stands were grown at low (200 μmol mol -1 ) or high CO 2 (1000 μmol mol -1 ) in controlled environment mesocosms. CUE of stands was measured by dynamic stand-scale 13 C labelling and partitioning of photosynthesis and respiration. At the same plant age, growth at high CO 2 (compared with low CO 2 ) led to 91% higher rates of apparent photosynthesis, 97% higher respiration in the dark, yet 143% higher respiration in light. Thus, CUE was significantly lower at high (0.65) than at low CO 2 (0.71). Compartmental analysis of isotopic tracer kinetics demonstrated a greater commitment of carbon reserves in stand-scale respiratory metabolism at high CO 2 . Two main processes contributed to the reduction of CUE at high CO 2 : a reduced inhibition of leaf respiration by light and a diminished leaf mass ratio. This work highlights the relevance of measuring respiration in light and assessment of the CUE response to environment conditions. © 2016 John Wiley & Sons Ltd.

The competitive status of trees determines their responsiveness to increasing atmospheric humidity - a climate trend predicted for northern latitudes.

PubMed

Tullus, Arvo; Kupper, Priit; Kaasik, Ants; Tullus, Hardi; Lõhmus, Krista; Sõber, Anu; Sellin, Arne

2017-05-01

The interactive effects of climate variables and tree-tree competition are still insufficiently understood drivers of forest response to global climate change. Precipitation and air humidity are predicted to rise concurrently at high latitudes of the Northern Hemisphere. We investigated whether the growth response of deciduous trees to elevated air humidity varies with their competitive status. The study was conducted in seed-originated silver birch and monoclonal hybrid aspen stands grown at the free air humidity manipulation (FAHM) experimental site in Estonia, in which manipulated stands (n = 3 for both species) are exposed to artificially elevated relative air humidity (6-7% over the ambient level). The study period included three growing seasons during which the stands had reached the competitive stage (trees were 7 years old in the final year). A significant 'treatment×competitive status' interactive effect on growth was detected in all years in birch (P < 0.01) and in one year in aspen stands (P = 0.015). Competitively advantaged trees were always more strongly affected by elevated humidity. Initially the growth of advantaged and neutral trees of both species remained significantly suppressed in humidified stands. In the following years, dominance and elevated humidity had a synergistic positive effect on the growth of birches. Aspens with different competitive status recovered more uniformly, attaining similar relative growth rates in manipulated and control stands, but preserved a significantly lower total growth yield due to severe initial growth stress. Disadvantaged trees of both species were never significantly affected by elevated humidity. Our results suggest that air humidity affects trees indirectly depending on their social status. Therefore, the response of northern temperate and boreal forests to a more humid climate in future will likely be modified by competitive relationships among trees, which may potentially affect species composition and cause a need to change forestry practices. © 2016 John Wiley & Sons Ltd.

Examination of Aircraft Interior Emergency Lighting in a Postcrash Fire Environment.

DTIC Science & Technology

1982-06-01

levels under realistic external fuel-fire conditions; (3) to compare black fuel-fire smoke with an enert white screen fog (references I and 2); (4... black smoke condition" at 52 seconds after the fuel fire was ignited and zero visibility a the 60-inch level at 120 seconds. Because it was closer to the...suitable stand was fabricated for each sign and the holes designed for aircraft mounting were utilized for securing the light to the stand. Two 28 AVG

Resonance fluorescence microscopy via three-dimensional atom localization

NASA Astrophysics Data System (ADS)

Panchadhyayee, Pradipta; Dutta, Bibhas Kumar; Das, Nityananda; Mahapatra, Prasanta Kumar

2018-02-01

A scheme is proposed to realize three-dimensional (3D) atom localization in a driven two-level atomic system via resonance fluorescence. The field arrangement for the atom localization involves the application of three mutually orthogonal standing-wave fields and an additional traveling-wave coupling field. We have shown the efficacy of such field arrangement in tuning the spatially modulated resonance in all directions. Under different parametric conditions, the 3D localization patterns originate with various shapes such as sphere, sheets, disk, bowling pin, snake flute, flower vase. High-precision localization is achieved when the radiation field detuning equals twice the combined Rabi frequencies of the standing-wave fields. Application of a traveling-wave field of suitable amplitude at optimum radiation field detuning under symmetric standing-wave configuration leads to 100% detection probability even in sub-wavelength domain. Asymmetric field configuration is also taken into consideration to exhibit atom localization with appreciable precision compared to that of the symmetric case. The momentum distribution of the localized atoms is found to follow the Heisenberg uncertainty principle under the validity of Raman-Nath approximation. The proposed field configuration is suitable for application in the study of atom localization in an optical lattice arrangement.

Predictors of Competency to Stand Trial in Connecticut's Inpatient Juvenile Competency Restoration Program.

PubMed

Chien, Joseph; Coker, Kendell L; Parke, Susan; Tejani, Nabyl; Sirken, Remy A; Sanchez-Jaquez, Christina; Rausch, Fernando; Azeem, Muhammad W

2016-12-01

There are substantial differences between adults and juveniles in the context of competency restoration. Among juveniles, factors such as maturity level, age, intellectual functioning, and psychiatric diagnoses may affect competency to stand trial. In this study, subjects included all juveniles who were admitted to the Albert J. Solnit Children's Center for inpatient competency restoration in the period spanning January 1, 2005, through December 31, 2012. Sixty-one juveniles were referred during this period, and 58 were included in the final analyses. Several demographic and clinical variables were tested to identify which factors were associated with successful competency restoration. There was a high rate of psychiatric comorbidity in the sample, with 54 of 58 juveniles (93%), having more than one Axis I disorder. IQ was the only significant predictor of successful competency restoration. These findings suggest that cognitive limitations may be a robust predictor of competency restoration among juveniles who are deemed incompetent to stand trial. Furthermore, policy makers may want to consider more specialized services for youths whose intellectual deficits are severe enough to impact their ability to regain competency. Limitations of this study, policy recommendations, and suggestions for future research are discussed. © 2016 American Academy of Psychiatry and the Law.

Enhancing Variable Friction Tactile Display Using an Ultrasonic Travelling Wave.

PubMed

Ghenna, Sofiane; Vezzoli, Eric; Giraud-Audine, Christophe; Giraud, Frederic; Amberg, Michel; Lemaire-Semail, Betty

2017-01-01

In Variable Friction Tactile Displays, an ultrasonic standing wave can be used to reduce the friction coefficient between a user's finger sliding and a vibrating surface. However, by principle, the effect is limited by a saturation due to the contact mechanics, and very low friction levels require very high vibration amplitudes. Besides, to be effective, the user's finger has to move. We present a device which uses a travelling wave rather than a standing wave. We present a control that allows to realize such a travelling wave in a robust way, and thus can be implemented on various plane surfaces. We show experimentally that the force produced by the travelling wave has two superimposed contributions. The first one is equal to the friction reduction produced by a standing of the same vibration amplitude. The second produces a driving force in the opposite direction of the travelling wave. As a result, the modulation range of the tangential force on the finger can be extended to zero and even negative values. Moreover, the effect is dependant on the relative direction of exploration with regards to the travelling wave, which is perceivable and confirmed by a psycho-physical study.

Snowshoe hare multi-level habitat use in a fire-adapted ecosystem

USGS Publications Warehouse

Gigliotti, Laura C.; Jones, Benjamin C.; Lovallo, Matthew J.; Diefenbach, Duane R.

2018-01-01

Prescribed burning has the potential to improve habitat for species that depend on pyric ecosystems or other early successional vegetation types. For species that occupy diverse plant communities over the extent of their range, response to disturbances such as fire might vary based on post-disturbance vegetation dynamics among plant communities. Although responses of snowshoe hares (Lepus americanus) to fire have been studied in conifer-dominated forests in northern parts of the species’ range, there is a lack of information on snowshoe hare habitat use in fire-dependent communities in southern parts of their range. We used global positioning system (GPS) and very high frequency (VHF) radio-collars to monitor the habitat use of 32 snowshoe hares in a scrub-oak (Quercus ilicifolia)-pitch pine (Pinus rigida) barrens complex in northeastern Pennsylvania where prescribed fire has been used for habitat restoration. The area contained stands that underwent prescribed burning 1–6 years prior to our study. Also, we investigated fine-scale determinants of habitat use within stands. We found that regardless of season, hares did not select for areas that had been burned within 6 years prior. Hares primarily used stands of older scrub oak, conifer, or hardwoods, which contained dense understory vegetation and canopy cover. Hare habitat use also was positively associated with stand edges. Our results suggest that hares do not respond to prescribed burning of scrub oak in the short-term. In addition, by focusing on structural determinants of habitat use, rather than broad-scale characteristics such as stand type, management strategies for snowshoe hares can be adapted over the extent of their range despite the multitude of different land cover types across which the species occurs. 

Miscarriage and occupational activity: a systematic review and meta-analysis regarding shift work, working hours, lifting, standing, and physical workload.

PubMed

Bonde, Jens Peter; Jørgensen, Kristian Tore; Bonzini, Matteo; Palmer, Keith T

2013-07-01

Previous studies have indicated that shift work, long working hours, and prevalent workplace exposures such as lifting, standing, and physical workload increase the risk of miscarriage, but the evidence is conflicting. We conducted a systematic review of original research reports. A search in Medline and EMBASE 1966-2012 identified 30 primary papers reporting the relative risk (RR) of miscarriage according to ≥1 of 5 occupational activities of interest. Following an assessment of completeness of reporting, confounding, and bias, each risk estimate was characterized as more or less likely to be biased. Studies with equivalent measures of exposure were pooled to obtain a weighted common risk estimate. Sensitivity analyses excluded studies most likely to be biased. Working fixed nights was associated with a moderately increased risk of miscarriage (pooled RR 1.51 [95% confidence interval (95% CI) 1.27-1.78, N=5), while working in 3-shift schedules, working for 40-52 hours weekly, lifting >100 kg/day, standing >6-8 hours/day and physical workload were associated with small risk increments, with the pooled RR ranging from 1.12 (3-shift schedule, N=7) to 1.36 (working hours, N=10). RR for working hours and standing became smaller when analyses were restricted to higher quality studies. These largely reassuring findings do not provide a strong case for mandatory restrictions in relation to shift work, long working hours, occupational lifting, standing, and physical workload. Considering the limited evidence base, however, it may be prudent to advise women against work entailing high levels of these exposures and women with at-risk pregnancies should receive tailored individual counseling.

Thirty Years of Change in Subalpine Forest Cover from Landsat Image Analysis in the Sierra Nevada Mountains of California

NASA Technical Reports Server (NTRS)

Potter, Christopher

2015-01-01

Landsat imagery was analyzed to understand changes in subalpine forest stands since the mid-1980s in the Sierra-Nevada region of California. At locations where long-term plot measurements have shown that stands are becoming denser in the number of small tree stems (compared to the early 1930s), the 30-year analysis of Landsat greenness index (NDVI) indicated that no consistent increases in canopy leaf cover have occurred at these same locations since the mid-1980s. Interannual variations in stand NDVI closely followed snow accumulation amounts recorded at nearby stations. In contrast, at eastern Sierra whitebark pine stand locations where it has been observed that widespread tree mortality has occurred, decreasing NDVI trends over the past 5-10 years were consistent with rapid loss of forest canopy cover. Landsat imagery was further analyzed to understand patterns of post-wildfire vegetation recovery, focusing on high burn severity (HBS) patches within burned areas dating from the late 1940s. Analysis of landscape metrics showed that the percentage of total HBS area comprised by the largest patch of recovered woody cover was relatively small in all fires that occurred since 1995, but increased rapidly with time since fire. Patch complexity of recovered woody cover decreased notably after more than 50 years of regrowth, but was not readily associated with time for fires that occurred since the mid 1990s. The aggregation level of patches with recovery of woody cover increased steadily with time since fire. The study approach using satellite remote sensing can be expanded to assess the consequences of stand-replacing wildfires in all forests of the region.

Homeostatic maintenance of ponderosa pine gas exchange in response to stand density changes.

PubMed

McDowell, Nate G; Adams, Henry D; Bailey, John D; Hess, Marcey; Kolb, Thomas E

2006-06-01

Homeostatic maintenance of gas exchange optimizes carbon gain per water loss. Homeostasis is regulated by short-term physiological and long-term structural mechanisms, both of which may respond to changes in resource availability associated with competition. Therefore, stand density regulation via silvicultural manipulations may facilitate growth and survival through mechanisms operating at both short and long timescales. We investigated the responses of ponderosa pine (Pinus ponderosa) to stand basal area manipulations in Arizona, USA. Stand basal area was manipulated to seven replicated levels in 1962 and was maintained for four decades by decadal thinning. We measured basal area increment (BAI) to assess the response and sustainability of wood growth, carbon isotope discrimination (A) inferred from annual rings to assess the response of crown gas exchange, and ratios of leaf area to sapwood area (A(l):A(s)) to assess longer term structural acclimation. Basal area treatments increased soil water potential (r2 = 0.99) but did not affect photosynthetic capacity. BAI increased within two years of thinning, and the 40-year mean BAI was negatively correlated with stand basal area (r2 = 0.98). delta was negatively correlated with stand basal area for years 5 through 12 after thinning (r2 = 0.90). However, delta was relatively invariant with basal area for the period 13-40 years after initial thinning despite maintenance of treatment basal areas via repeated decadal thinnings. Independent gas exchange measurements verified that the ratio of photosynthesis to stomatal conductance was invariant with basal area, but absolute values of both were elevated at lower basal areas. A(l):A(s) was negatively correlated with basal area (r2 = 0.93). We hypothesize that increased A(l):A(s) is a homeostatic response to increased water availability that maximizes water-use efficiency and whole-tree carbon uptake. Elevated A(l):A(s) of trees at low basal areas was associated with greater resilience to climate, i.e., greater absolute BAI during drought; however, trees with high A(l):A(s) in low basal area stands also exhibited the greatest sensitivity to drought, i.e., greater relative decline in BAI.

Rasterstereographic analysis of axial back surface rotation in standing versus forward bending posture in idiopathic scoliosis.

PubMed

Hackenberg, Lars; Hierholzer, Eberhard; Bullmann, Viola; Liljenqvist, Ulf; Götze, Christian

2006-07-01

The forward bending test according to Adams and rib hump quantification by scoliometer are common clinical examination techniques in idiopathic scoliosis, although precise data about the change of axial surface rotation in forward bending posture are not available. In a pilot study the influence of leg length inequalities on the back shape of five normal subjects was clarified. Then 91 patients with idiopathic scoliosis with Cobb-angles between 20 degrees and 82 degrees were examined by rasterstereography, a 3D back surface analysis system. The axial back surface rotation in standing posture was compared with that in forward bending posture and additionally with a scoliometer measurement in forward bending posture. The changes of back shape in forward bending posture were correlated with the Cobb-angle, the level of the apex of the scoliotic primary curve and the age of the patient. Averaged over all patients, the back surface rotation amplitude increased from 23.1 degrees in standing to 26.3 degrees in forward bending posture. The standard deviation of this difference was high (6.1 degrees ). The correlation of back surface rotation amplitude in standing with that in forward bending posture was poor (R (2)=0.41) as was the correlation of back surface rotation in standing posture with the scoliometer in forward bending posture measured rotation (R (2)=0.35). No significant correlation could be found between the change of back shape in forward bending and the degree of deformity (R (2)=0.07), likewise no correlation with the height of the apex of the scoliosis (R (2)=0.005) and the age of the patient (R (2)=0.001). Before forward bending test leg length inequalities have to be compensated accurately. Compared to the standing posture, forward bending changes back surface rotation. However, this change varies greatly between patients, and is independent of the type and degree of scoliosis. Furthermore remarkable differences were found between scoliometer measurement of the rib hump and rasterstereographic measurement of the vertebral rotation. Therefore the forward bending test and the identification of idiopathic scoliosis rotation by scoliometer can be markedly different compared to rasterstereographic surface measurement in the standing posture.

Sugar maple growth in relation to nutrition and stress in the northeastern United States.

PubMed

Long, Robert P; Horsley, Stephen B; Hallett, Richard A; Bailey, Scott W

2009-09-01

Sugar maple, Acer saccharum, decline disease is incited by multiple disturbance factors when imbalanced calcium (Ca), magnesium (Mg), and manganese (Mn) act as predisposing stressors. Our objective in this study was to determine whether factors affecting sugar maple health also affect growth as estimated by basal area increment (BAI). We used 76 northern hardwood stands in northern Pennsylvania, New York, Vermont, and New Hampshire, USA, and found that sugar maple growth was positively related to foliar concentrations of Ca and Mg and stand level estimates of sugar maple crown health during a high stress period from 1987 to 1996. Foliar nutrient threshold values for Ca, Mg, and Mn were used to analyze long-term BAI trends from 1937 to 1996. Significant (P < or = 0.05) nutrient threshold-by-time interactions indicate changing growth in relation to nutrition during this period. Healthy sugar maples sampled in the 1990s had decreased growth in the 1970s, 10-20 years in advance of the 1980s and 1990s decline episode in Pennsylvania. Even apparently healthy stands that had no defoliation, but had below-threshold amounts of Ca or Mg and above-threshold Mn (from foliage samples taken in the mid 1990s), had decreasing growth by the 1970s. Co-occurring black cherry, Prunus serotina, in a subset of the Pennsylvania and New York stands, showed opposite growth responses with greater growth in stands with below-threshold Ca and Mg compared with above-threshold stands. Sugar maple growing on sites with the highest concentrations of foliar Ca and Mg show a general increase in growth from 1937 to 1996 while other stands with lower Ca and Mg concentrations show a stable or decreasing growth trend. We conclude that acid deposition induced changes in soil nutrient status that crossed a threshold necessary to sustain sugar maple growth during the 1970s on some sites. While nutrition of these elements has not been considered in forest management decisions, our research shows species specific responses to Ca and Mg that may reduce health and growth of sugar maple or change species composition, if not addressed.

Adaptations to Speed Endurance Training in Highly Trained Soccer Players.

PubMed

Nyberg, Michael; Fiorenza, Matteo; Lund, Anders; Christensen, Magnus; Rømer, Tue; Piil, Peter; Hostrup, Morten; Christensen, Peter M; Holbek, Simon; Ravnholt, Thomas; Gunnarsson, Thomas P; Bangsbo, Jens

2016-07-01

The present study examined whether a period of additional speed endurance training would improve intense intermittent exercise performance in highly trained soccer players during the season and whether the training changed aerobic metabolism and the level of oxidative enzymes in type I and type II muscle fibers. During the last 9 wk of the season, 13 semiprofessional soccer players performed additional speed endurance training sessions consisting of two to three sets of 8-10 repetitions of 30-m sprints with 10 s of passive recovery (SET). Before and after SET, subjects completed a double-step exercise protocol that included transitions from standing to moderate-intensity running (~75% HRmax), followed by transitions from moderate- to high-intensity running (~90% HRmax) in which pulmonary oxygen uptake (V˙O2) was determined. In addition, the yo-yo intermittent recovery test level 1 was performed, and a muscle biopsy was obtained at rest. The yo-yo intermittent recovery test level 1 performance was 11.6% ± 6.4% (mean ± SD) better (2803 ± 330 vs 3127 ± 383 m, P < 0.05) after SET compared with before SET. In the transition from standing to moderate-intensity running, phase II pulmonary V˙O2 kinetics was 11.4% ± 16.5% faster (P < 0.05), and the running economy at this intensity was 2.3% ± 3.0% better (P < 0.05). These improvements were apparent despite the content of muscle proteins regulating oxidative metabolism (3-hydroxyacyl CoA dehydrogenase, COX IV, and OXPHOS), and capillarization was reduced (P < 0.05). The content of 3-hydroxyacyl CoA dehydrogenase and citrate synthase in type I and type II fibers did not change. In highly trained soccer players, additional speed endurance training is associated with an improved ability to perform repeated high-intensity work. To what extent the training-induced changes in V˙O2 kinetics and mechanical efficiency in type I fibers caused the improvement in performance warrants further investigation.

From defective hardwood stand to multiple use opportunity

Treesearch

Charles E. McGee

1972-01-01

A 40-year old clearcutting, originally made as an example of destructive logging, now supports one of the best mixed hardwood stands on the Bent Creek Experimental Forest. Such desirable intolerants as yellow-poplar provide potential for timber; some high- and low-quality oaks provide timber and wildlife values; and the entire young stand has a pleasing appearance....

Effects of deer exclosures on oak regeneration in closed-canopy stands

Treesearch

Angela M. Yuska; Kim C. Steiner; James C. Finley

2008-01-01

Studies of the effects of high deer densities on forest regeneration have shown altered species composition and reduced diversity in stands regenerating after harvest. The effects of browsing in fully stocked, undisturbed stands are less well known but important, as establishment of seedlings of oaks and other species prior to disturbance is very important for self-...

SSC Test Operations Contract Overview

NASA Technical Reports Server (NTRS)

Kleim, Kerry D.

2010-01-01

This slide presentation reviews the Test Operations Contract at the Stennis Space Center (SSC). There are views of the test stands layouts, and closer views of the test stands. There are descriptions of the test stand capabilities, some of the other test complexes, the Cryogenic propellant storage facility, the High Pressure Industrial Water (HPIW) facility, and Fluid Component Processing Facility (FCPF).

Converting Virginia pine stump diameters to diameters breast high

Treesearch

Thomas W., Jr. Church

1953-01-01

Up until the last decade, practically no forest-management work had been done in stands of Virginia pine (Pinus virginiana Miller). It is still common practice to clear-cut the stand - with no consideration for a future crop. In some places this has resulted in satisfactory establishment of another pine stand. But usually hardwoods take over the site...

Development of a Thrust Stand to Meet LISA Mission Requirements

NASA Technical Reports Server (NTRS)

Willis, William D., III; Zakrzwski, Charles M.; Merkowitz, Stephen M.

2002-01-01

A thrust stand has been built to measure the force-noise produced by electrostatic micro-Newton (muN) thrusters. The LISA mission's Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 muN with a resolution of 0.1 muN. The stationary force-noise produced by these thrusters must not exceed 0.1 muN/dHz in the measurement bandwidth 10(exp -4) to 1 Hz. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from l0( -4) to 1 Hz with 0.1 muN/dHz sensitivity, absolute thrust measurements from 1-100 muN with better than 0.1 muN resolution, and dynamic thruster response from to 10 Hz. The LTS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.

Development of A Thrust Stand to Meet LISA Mission Requirements

NASA Technical Reports Server (NTRS)

Willis, William D., III; Zakrzwski, C. M.; Bauer, Frank H. (Technical Monitor)

2002-01-01

A thrust stand has been built and tested that is capable of measuring the force-noise produced by electrostatic micro-Newton (micro-Newton) thrusters. The LISA mission's Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 micro-Newton with a resolution of 0.1 micro-Newton. The stationary force-noise produced by these thrusters must not exceed 0.1 pN/4Hz in a 10 Hz bandwidth. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from 10(exp-4) to 1 Hz with 0.1 micro-Newton resolution, absolute thrust measurements from 1-100 micro-Newton with better than 0.1 micro-Newton resolution, and dynamic thruster response from 10(exp -4) to 10 Hz. The ITS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.

Sway‐dependent changes in standing ankle stiffness caused by muscle thixotropy

PubMed Central

Sakanaka, Tania E.; Lakie, Martin

2016-01-01

Key points The passive stiffness of the calf muscles contributes to standing balance, although the properties of muscle tissue are highly labile.We investigated the effect of sway history upon intrinsic ankle stiffness and demonstrated reductions in stiffness of up to 43% during conditions of increased baseline sway.This sway dependence was most apparent when using low amplitude stiffness‐measuring perturbations, and the short‐range stiffness component was smaller during periods of high sway.These characteristics are consistent with the thixotropic properties of the calf muscles causing the observed changes in ankle stiffness.Periods of increased sway impair the passive stabilization of standing, demanding more active neural control of balance. Abstract Quiet standing is achieved through a combination of active and passive mechanisms, consisting of neural control and intrinsic mechanical stiffness of the ankle joint, respectively. The mechanical stiffness is partly determined by the calf muscles. However, the viscoelastic properties of muscle are highly labile, exhibiting a strong dependence on movement history. By measuring the effect of sway history upon ankle stiffness, the present study determines whether this lability has consequences for the passive stabilization of human standing. Ten subjects stood quietly on a rotating platform whose axis was collinear with the ankle joint. Ankle sway was increased by slowly tilting this platform in a random fashion, or decreased by fixing the body to a board. Ankle stiffness was measured by using the same platform to simultaneously apply small, brief perturbations (<0.6 deg; 140 ms) at the same time as the resulting torque response was recorded. The results show that increasing sway reduces ankle stiffness by up to 43% compared to the body‐fixed condition. Normal quiet stance was associated with intermediate values. The effect was most apparent when using smaller perturbation amplitudes to measure stiffness (0.1 vs. 0.6 deg). Furthermore, torque responses exhibited a biphasic pattern, consisting of an initial steep rise followed by a shallower increase. This transition occurred earlier during increased levels of ankle sway. These results are consistent with a movement‐dependent change in passive ankle stiffness caused by thixotropic properties of the calf muscle. The consequence is to place increased reliance upon active neural control during times when increased sway renders ankle stiffness low. PMID:26607292

Healthy Concessions: High School Students' Responses to Healthy Concession Stand Changes

ERIC Educational Resources Information Center

Laroche, Helena H.; Hradek, Christine; Hansen, Kate; Hanks, Andrew S.; Just, David R.; Wansink, Brian

2017-01-01

Background: A previous sales data analysis demonstrated success in selling healthier items at a concession stand. Questions remained regarding student satisfaction and whether the intervention reached non-health-conscious students. Methods: Cross-sectional anonymous samples of students at a large midwestern high school were surveyed before and…

High-precision R-branch transition frequencies in the ν2 fundamental band of H 3+ %A Perry, Adam J.; Hodges, James N.; Markus, Charles R.; Kocheril, G. Stephen; McCall, Benjamin J.

NASA Astrophysics Data System (ADS)

Perry, Adam J.; Hodges, James N.; Markus, Charles R.; Kocheril, G. Stephen; McCall, Benjamin J.

2015-11-01

The H3+ molecular ion has served as a long-standing benchmark for state-of-the-art ab initio calculations of molecular potentials and variational calculations of rovibrational energy levels. However, the accuracy of such calculations would not have been confirmed if not for the wealth of spectroscopic data that has been made available for this molecule. Recently, a new high-precision ion spectroscopy technique was demonstrated by Hodges et al., which led to the first highly accurate and precise (∼MHz) H3+ transition frequencies. As an extension of this work, we present ten additional R-branch transitions measured to similar precision as a next step toward the ultimate goal of producing a comprehensive high-precision survey of this molecule, from which rovibrational energy levels can be calculated.