Death by attrition: a hypothesis for wave mortality of subalpine Abiesbalsamea

1986 ◽  
Vol 16 (3) ◽  
pp. 591-596 ◽  
Author(s):  
Peter J. Marchand ◽  
France L. Goulet ◽  
Thomas C. Harrington
Keyword(s):  
Wave Front ◽  
Energy Demand ◽  
Substantial Reduction ◽  
Leading Edge ◽  
Compact Zone ◽  
Fold Reduction ◽  
Xylem Discoloration ◽  
Substantial Decline ◽  
Individual Trees ◽  
Mature Stands

Wave mortality in subalpine Abies forests of the northeastern United States is characterized by the progressive dieback of overstory dominants in a compact zone that advances systematically through mature stands and is followed by vigorous regeneration of the overstory species. The principal driving force for this dieback appears to be exposure at the edge of canopy gaps to very high winds. In this study, individual trees at the leading edge of a dieback front and trees in a thinned plot within the mature stand downwind of the advancing wave both experienced a substantial decline in foliage mass and, consequently, in prebudbreak foliar starch pool over a 2-year period. In the case of the thinned stand, this reduction was attributed to a large increase in wintertime green litter fall. Increased exposure at the wave front and in the thinned stand also resulted in a dramatic increase in root damage relative to control trees. Coincidental to breakage of roots, root xylem discoloration (attributed to wounding and invasion by root pathogens) was greater on trees at the wave front than on trees in the mature zone. Loss of active foliage and roots was accompanied by a two- to five-fold reduction in annual wood increment among dieback zone trees. These data suggest that exposed trees, which suffer a substantial reduction in crown size and foliage carbohydrate pool in an environment where growth is marginal to begin with, may not be able to keep up with the increased energy demand for root and foliage turnover and eventually suffer death by attrition of both tissues.

Performance of a High Tip Speed Ratio H-Darrieus in the Skewed Flow on a Roof

2003 ◽  
Author(s):  
Sander Mertens ◽  
Gijs van Kuik ◽  
Gerard van Bussel
Keyword(s):  
Wind Turbines ◽  
Power Output ◽  
Energy Demand ◽  
Leading Edge ◽  
Spatial Dimension ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Blade Element Theory ◽  
Excess Power ◽  
Flat Roof

Small wind turbines sited on a flat roof have good opportunities to become widespread. They operate in the accelerated wind above the roof and deliver the power where it is needed. Since the power produced offsets that which would otherwise be bought from the utility, they reduce energy demand and bills from the utility. Furthermore excess power can be sold back to the utility, thus producing income as well. Flow over a building separates at the roof leading edge at a certain angle. Wind turbines sited well above the roof thus operate in skewed flow. H-Darrieus operating at (flat) roofs just recently start to be at public interest, operation of an H-Darrieus in skewed flow is thus not discussed in literature until now. To examine this, a model of an H-Darrieus with high Tip Speed Ratio (λ) in skewed flow is developed. The model is based on multiple stream-tube theory: a combination of axial momentum and blade element theory on an actuator plate representation of the rotor, which is divided into multiple stream-tubes. The model shows that, for an H-Darrieus designed for skewed flow, the optimal power output in skewed flow can be up to two times the power output in normal - perpendicular to the H-Darrieus axis- flow. The spatial dimension of the H-Darrieus is responsible for this.

scholarly journals Material efficiency: providing material services with less material production

2013 ◽  
Vol 371 (1986) ◽  
pp. 20120496 ◽  
Author(s):  
Julian M. Allwood ◽  
Michael F. Ashby ◽  
Timothy G. Gutowski ◽  
Ernst Worrell
Keyword(s):  
Energy Demand ◽  
Business Models ◽  
Consumer Preferences ◽  
Substantial Reduction ◽  
Building Design ◽  
High Volume ◽  
Well Being ◽  
Carbon Price ◽  
Material Production ◽  
Material Efficiency

Material efficiency, as discussed in this Meeting Issue, entails the pursuit of the technical strategies, business models, consumer preferences and policy instruments that would lead to a substantial reduction in the production of high-volume energy-intensive materials required to deliver human well-being. This paper, which introduces a Discussion Meeting Issue on the topic of material efficiency, aims to give an overview of current thinking on the topic, spanning environmental, engineering, economics, sociology and policy issues. The motivations for material efficiency include reducing energy demand, reducing the emissions and other environmental impacts of industry, and increasing national resource security. There are many technical strategies that might bring it about, and these could mainly be implemented today if preferred by customers or producers. However, current economic structures favour the substitution of material for labour, and consumer preferences for material consumption appear to continue even beyond the point at which increased consumption provides any increase in well-being. Therefore, policy will be required to stimulate material efficiency. A theoretically ideal policy measure, such as a carbon price, would internalize the externality of emissions associated with material production, and thus motivate change directly. However, implementation of such a measure has proved elusive, and instead the adjustment of existing government purchasing policies or existing regulations— for instance to do with building design, planning or vehicle standards—is likely to have a more immediate effect.

Improving the Assessment of Flow-Mediated Dilation Through Detection of Peak Time in Healthy Subjects and Subjects With Type 2 Diabetes

Angiology ◽  
2020 ◽  
pp. 000331972098488
Author(s):  
Theresa Herbrand ◽  
Hans-Veit Coester ◽  
Roberto Sansone ◽  
Annelie Fischer ◽  
Christian Heiss ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Sample Size ◽  
Healthy Subjects ◽  
Substantial Reduction ◽  
Intraindividual Variability ◽  
Peak Time ◽  
Flow Mediated Dilation ◽  
Fold Reduction ◽  
Precise Assessment

The assessment of flow-mediated dilation (FMD) is widely used to quantify endothelial function. Historically, FMD was determined at 60 seconds post-cuff deflation. We investigated whether FMD would be more accurate if determined at maximum dilatory peak (MDP) than at 60 seconds in healthy subjects and subjects with type 2 diabetes mellitus (T2DM). We studied 95 healthy and 72 subjects with T2DM and assessed FMD at MDP, 60 and 90 seconds. Twenty-four healthy and 12 subjects with T2DM underwent a repeat FMD after 28 days. In healthy subjects, FMD at MDP was higher than at 60 and 90 seconds, with mean difference MDP versus 60 seconds 1.14% (95% CI: 0.6-1.7); P < .0001 and MDP versus 90 seconds 1.9% (95% CI: 1.3-2.5) with similar results in T2DM, that is, 1.0% (95% CI: 0.1-1.9) and 2.3% (95% CI: 1.3-3.2), respectively. Intraindividual variability was lowest with MDP compared with 60 and 90 seconds, that is, 15.0 versus 23.2% and 40.0%, respectively, resulting in a more than 2-fold reduction in necessary sample size. In healthy subjects and subjects with T2DM, assessment of FMD using MDP results in a more accurate and precise assessment leading to a substantial reduction in sample size.

scholarly journals Actopaxin, a New Focal Adhesion Protein That Binds Paxillin Ld Motifs and Actin and Regulates Cell Adhesion

2000 ◽  
Vol 151 (7) ◽  
pp. 1435-1448 ◽  
Author(s):  
Sotiris N. Nikolopoulos ◽  
Christopher E. Turner
Keyword(s):  
Cell Adhesion ◽  
Actin Cytoskeleton ◽  
Focal Adhesion ◽  
Substantial Reduction ◽  
Ectopic Expression ◽  
Focal Adhesions ◽  
Leading Edge ◽  
Cell Types ◽  
Focal Adhesion Protein

Paxillin is a focal adhesion adapter protein involved in the integration of growth factor– and adhesion-mediated signal transduction pathways. Paxillin LD motifs have been demonstrated to bind to several proteins associated with remodeling of the actin cytoskeleton including the focal adhesion kinase, vinculin, and a complex of proteins comprising p95PKL, PIX, and PAK (Turner, C.E., M.C. Brown, J.A. Perrotta, M.C. Riedy, S.N. Nikolopoulos, A.R. McDonald, S. Bagrodia, S. Thomas, and P.S. Leventhal. 1999. J. Cell Biol. 145:851–863). In this study, we report the cloning and initial characterization of a new paxillin LD motif–binding protein, actopaxin. Analysis of the deduced amino acid sequence of actopaxin reveals a 42-kD protein with two calponin homology domains and a paxillin-binding subdomain (PBS). Western blotting identifies actopaxin as a widely expressed protein. Actopaxin binds directly to both F-actin and paxillin LD1 and LD4 motifs. It exhibits robust focal adhesion localization in several cultured cell types but is not found along the length of the associated actin-rich stress fibers. Similar to paxillin, it is absent from actin-rich cell–cell adherens junctions. Also, actopaxin colocalizes with paxillin to rudimentary focal complexes at the leading edge of migrating cells. An actopaxin PBS mutant incapable of binding paxillin in vitro cannot target to focal adhesions when expressed in fibroblasts. In addition, ectopic expression of the PBS mutant and/or the COOH terminus of actopaxin in HeLa cells resulted in substantial reduction in adhesion to collagen. Together, these results suggest an important role for actopaxin in integrin-dependent remodeling of the actin cytoskeleton during cell motility and cell adhesion.

scholarly journals COMP-01. MODELING THE EVOLUTION OF PLOIDY IN A RESOURCE RESTRICTED ENVIRONMENT

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi61-vi61
Author(s):  
Noemi Andor ◽  
Jill Barnholtz-Sloan ◽  
Hanlee Ji
Keyword(s):  
Energy Demand ◽  
Cell Cycle Progression ◽  
Leading Edge ◽  
Giant Cells ◽  
High Energy ◽  
Integrin Signaling ◽  
Cell Phenotype ◽  
Lower Grade ◽  
Sequencing Data ◽  
High Ploidy

Abstract Progression of lower-grade gliomas (LGG) to glioblastoma (GBM) is accompanied by a phenotypic switch to an invasive cell phenotype. Converging evidence from colorectal-, breast-, and lung-cancers, suggests a strong enrichment of high ploidy cells among metastatic lesions as compared to the primary. Even in normal development: trophoblast giant cells are responsible for invading the placenta during embryogenesis and these cells often have tens of copies of the genome. We formulate a mechanistic Grow-or-go model that postulates higher energy demands of high-ploidy cells as driver of invasive behavior. The unit we are modeling is a cell, that comes with a certain ploidy, proliferation-, and death-rate. Variations in ploidy emerge as a result of chromosome missegregations. For each cell we calculate the probability of cell-division as a function of energy availability in the neighborhood vs. ploidy-dependent energy demand of the cell. Underlying this comparison is the dual role of integrin signaling: integrin-mediated signals allow cells to progress from G1 to S-phase. At the same time integrins mediate cell migration. The model was implemented as a cellular automaton and 2,500 simulations were ran at variable energies and missegregation rates. In low-energy environments high-ploidy clones were enriched at the leading edge of the tumor. This was not the case in high-energy environments. We applied the model to analyze previously published exome sequencing data from 14 multi-spatial and longitudinal LGG biopsies. Using the size and ploidy of co-existing clones as summary statistics for Approximate Bayesian Computation, we infer relative chromosome missegregation rates in primary LGG. A higher missegregation rate was predictive of faster progression of LGG to GBM (multivariate Cox: HR = 7.96, P = 0.041). Future validation experiments will evaluate the potential of the model to explain differences in the prognostic power of integrin signaling and cell cycle progression between males and females.

scholarly journals Synthesis and Performance of TiO2/Fly Ash Cenospheres as a Catalytic Film in a Novel Type of Periodic Air-Sparged Photocatalytic Reactor

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1691 ◽  
Author(s):  
Witold Żukowski ◽  
Przemysław Migas ◽  
Dariusz Bradło ◽  
Piotr Dulian
Keyword(s):  
Fly Ash ◽  
Energy Demand ◽  
Film Formation ◽  
Surface Film ◽  
Substantial Reduction ◽  
Point Of View ◽  
Fluidised Bed ◽  
Photocatalytic Reactor ◽  
Continuous Mixing ◽  
Fly Ash Cenospheres

The results of a photocatalytic process performed in a new type of inclined, three-phase fluidised bed reactor with a periodic photocatalyst film are presented. These phases were fly ash cenospheres coated with TiO2, an aqueous solution of methylene blue and an air stream passing from the bottom of the photoreactor. The cenospheres have a density lower than water and could thus form a catalytic film on a top irradiated window. The formed surface film is stable but is easy to break and be reproduced in a cyclic air-sparged process. Mixing was performed in either a cyclic or a continuous manner. From an operational point of view, the best variant of mixing was a 10 s air-sparge/10 s break with a 50% duty cycle, because it provided the same discolouration efficiency and reduced energy demand by 50% in comparison with the continuous mixing. Due to film formation, the proposed catalytic reactor enables a substantial reduction in the energy required for mixing while maintaining the desired degree of discolouration.

scholarly journals Plasmodium vivax Relapse Rates Following Plasmodium falciparum Malaria Reflect Previous Transmission Intensity

2019 ◽  
Vol 220 (1) ◽  
pp. 100-104 ◽  
Author(s):  
Elizabeth A Ashley ◽  
Aung Pyae Phyo ◽  
Verena I Carrara ◽  
Kyaw Myo Tun ◽  
Francois Nosten ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Falciparum Malaria ◽  
Vivax Malaria ◽  
Substantial Reduction ◽  
Plasmodium Falciparum Malaria ◽  
Transmission Intensity ◽  
Fold Reduction ◽  
Plasmodium Vivax Malaria

Abstract From 2003 through 2009, 687 of 2885 patients (23.8%) treated for Plasmodium falciparum malaria in clinical studies in Myanmar or on the Thailand-Myanmar border had recurrent Plasmodium vivax malaria within 63 days, compared with 18 of 429 patients (4.2%) from 2010 onward (risk ratio [RR], 0.176; 95% confidence interval, .112–.278; P &lt; .0001). Corresponding data from 42 days of follow-up revealed that 820 of 3883 patients (21.1%) had recurrent P. vivax malaria before 2010, compared with 22 of 886 (2.5%) from 2010 onward (RR, 0.117; 95% CI, .077–.177; P &lt; .0001). This 6-fold reduction suggests a recent decline in P. vivax transmission intensity and, thus, a substantial reduction in the proportion of individuals harboring hypnozoites.

scholarly journals Preliminary Evaluation of a Nuclear Scenario Involving Innovative Gas Cooled Reactors

2009 ◽  
Vol 2009 ◽  
pp. 1-16 ◽  
Author(s):  
Barbara Vezzoni ◽  
Nicola Cerullo ◽  
Giuseppe Forasassi ◽  
Emil Fridman ◽  
Guglielmo Lomonaco ◽  
...  
Keyword(s):  
Energy Demand ◽  
Energy Use ◽  
Raw Materials ◽  
Substantial Reduction ◽  
Electric Energy ◽  
Point Of View ◽  
Electricity Production ◽  
Reference Level ◽  
Preliminary Evaluation ◽  
Use Of Resources

In order to guarantee a sustainable supply of future energy demand without compromising the environment, some actions for a substantial reduction of emissions are nowadays deeply analysed. One of them is the improvement of the nuclear energy use. In this framework, innovative gas-cooled reactors (both thermal and fast) seem to be very attractive from the electricity production point of view and for the potential industrial use along the high temperature processes (e.g., production by steam reforming or I-S process). This work focuses on a preliminary (and conservative) evaluation of possible advantages that a symbiotic cycle (EPR-PBMR-GCFR) could entail, with special regard to the reduction of the HLW inventory and the optimization of the exploitation of the fuel resources. The comparison between the symbiotic cycle chosen and the reference one (once-through scenario, i.e., EPR-SNF directly disposed) shows a reduction of the time needed to reach a fixed reference level from 170000 years to 1550 years (comparable with typical human times and for this reason more acceptable by the public opinion). In addition, this cycle enables to have a more efficient use of resources involved: the total electric energy produced becomes equal to 630 TWh/year (instead of only 530 TWh/year using only EPR) without consuming additional raw materials.

scholarly journals CO2 capture and storage in Greece: A case study from komotini ngcc power plant

2006 ◽  
Vol 10 (3) ◽  
pp. 71-80
Author(s):  
Nikolaos Koukouzas ◽  
Paraskevas Klimantos ◽  
Prokopis Stogiannis ◽  
Emmanouel Kakaras
Keyword(s):  
Power Plant ◽  
Co2 Capture ◽  
Energy Demand ◽  
Power Plants ◽  
Fossil Fuel ◽  
Substantial Reduction ◽  
Plant Performance ◽  
Electricity Production ◽  
Electricity Production Cost ◽  
And Storage

The aim of this paper is to examine the possibilities for the abatement of CO2 emissions in the Greek fossil fuel power generation sector. An overview of CO2 capture, transportation, and storage concepts, on which the R&D community is focused, is presented. The implementation of post-combustion CO2 capture options in an existing fossil fuel power plant is then examined and the consequences on the overall plant performance are determined. Finally, the possibilities of transportation and then underground storage of the pure CO2 stream are analyzed taking into account both technical and economical factors. The results of this analysis show that CO2 sequestration is technically feasible for existing fossil fuel fired power plants in Greece. However, substantial reduction in plant efficiency is observed due to increased energy demand of the technologies used as well as in electricity production cost due to capital and operation costs of capture, transport, and storage of CO2. .

Approaches for estimating stand-level volume using terrestrial laser scanning in a single-scan mode

2014 ◽  
Vol 44 (6) ◽  
pp. 666-676 ◽  
Author(s):  
Rasmus Astrup ◽  
Mark J. Ducey ◽  
Aksel Granhus ◽  
Tim Ritter ◽  
Nikolas von Lüpke
Keyword(s):  
Laser Scanning ◽  
Single Point ◽  
Individual Tree ◽  
Transect Sampling ◽  
Laser Systems ◽  
Southern Norway ◽  
The Individual ◽  
Individual Trees ◽  
Mature Stands ◽  
Volume Estimates

The most efficient way to obtain stand inventory data with terrestrial laser systems (TLS) is with the single-scan mode, which involves taking one scan at a single point. With a single-scan setup, there will be a nondetection of trees in a plot and the representation of the individual trees will be incomplete. We explore how stand-level volume estimates, based on the single-scan mode, perform compared with standard inventory estimates. We base our study on 166 plots in 12 mature stands dominated by Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst) in southern Norway. First, we compare individual-tree volume estimates from TLS with estimates from volume functions and measurements from harvesters. We show that individual-tree volumes can be estimated with high precision and accuracy with TLS in single-scan mode. Secondly, we test three approaches for correction of nondetection relying on model-based estimates of the detection probability obtained by point transect sampling estimators. We show that all three approaches adjust for nondetection and yield stand-level volume estimates that are similar to those obtained by fixed-area sampling. In conclusion, our results indicate that stand-level volume estimates, based on single-scan mode TLS data, perform well compared with standard inventory estimates.

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