scholarly journals Multidimensional Structural Characterization is Required to Detect and Differentiate Among Moderate Disturbance Agents

2019 ◽  
Author(s):  
Jeff W. Atkins ◽  
Ben Bond-Lamberty ◽  
Robert T. Fahey ◽  
Brady S. Hardiman ◽  
Lisa Haber ◽  
...  
Keyword(s):  
Structural Changes ◽  
Canopy Structure ◽  
Detection Methods ◽  
Ice Storm ◽  
Storm Damage ◽  
Ecological Disturbance ◽  
Moderate Severity ◽  
Terrestrial Lidar ◽  
Ice Storms ◽  
Age Related

The study of vegetation community and structural change has been central to ecology for over a century, yet how disturbances reshape the physical structure of forest canopies remains relatively unknown. Moderate severity disturbance including fire, ice storms, insect and pathogen outbreaks, affects different canopy strata and plant species, which may give rise to variable structural outcomes and ecological consequences. Terrestrial lidar (light detection and ranging) offers an unprecedented view of the interior arrangement and distribution of canopy elements, permitting the derivation of multidimensional measures of canopy structure that describe several canopy structural traits with known linkages to ecosystem functioning. We used lidar-derived canopy structural measured within a machine learning framework to detect and differentiate among various disturbance agents, including moderate severity fire, ice storm damage, age-related senescence, hemlock woolly adelgid, beech bark disease, and chronic acidification. We found that disturbance agents such as fire and ice storms primarily affected the amount and position of vegetation within canopies, while acidification, pathogen and insect infestation, and senescence altered canopy arrangement and complexity. Only two of the six disturbance agents significantly reduced leaf area, indicating that this commonly quantified canopy feature is insufficient to characterize many moderate severity disturbances. Rather, measures of canopy structure, including those that describe multidimensional change, are needed to characterize disturbance at moderate severities because structural changes from these events are spatially and quantitatively variable. Our findings suggest that standard disturbance detection methods, such as optical based remote sensing platforms, may currently be limited in their ability to detect, differentiate, and characterize disturbance. Further, we conclude that a more broadly inclusive definition of ecological disturbance that incorporates multiple aspects of canopy structure change will improve the modeling, detection, and prediction of functional implications of moderate severity disturbance.

scholarly journals A Simulation Study Using Terrestrial LiDAR Point Cloud Data to Quantify Spectral Variability of a Broad-Leaved Forest Canopy

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3357 ◽  
Author(s):  
Renato Cifuentes ◽  
Dimitry Van der Zande ◽  
Christian Salas-Eljatib ◽  
Jamshid Farifteh ◽  
Pol Coppin
Keyword(s):  
Leaf Area ◽  
Forest Canopy ◽  
Structural Changes ◽  
Vegetation Indices ◽  
Canopy Structure ◽  
Point Clouds ◽  
3D Models ◽  
Area Index ◽  
Terrestrial Lidar ◽  
Cloud Data

In this analysis, a method for construction of forest canopy three-dimensional (3D) models from terrestrial LiDAR was used for assessing the influence of structural changes on reflectance for an even-aged forest in Belgium. The necessary data were extracted by the developed method, as well as it was registered the adjacent point-clouds, and the canopy elements were classified. Based on a voxelized approach, leaf area index (LAI) and the vertical distribution of leaf area density (LAD) of the forest canopy were derived. Canopy–radiation interactions were simulated in a ray tracing environment, giving suitable illumination properties and optical attributes of the different canopy elements. Canopy structure was modified in terms of LAI and LAD for hyperspectral measurements. It was found that the effect of a 10% increase in LAI on NIR reflectance can be equal to change caused by translating 50% of leaf area from top to lower layers. As presented, changes in structure did affect vegetation indices associated with LAI and chlorophyll content. Overall, the work demonstrated the ability of terrestrial LiDAR for detailed canopy assessments and revealed the high complexity of the relationship between vertical LAD and reflectance.

Effects of an experimental ice storm on forest canopy structure

2020 ◽  
Vol 50 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Robert T. Fahey ◽  
Jeff W. Atkins ◽  
John L. Campbell ◽  
Lindsey E. Rustad ◽  
Meghan Duffy ◽  
...  
Keyword(s):  
Forest Canopy ◽  
Canopy Structure ◽  
Specific Effect ◽  
Canopy Openness ◽  
Ice Accretion ◽  
Ice Storm ◽  
Structural Reorganization ◽  
Ice Storms ◽  
Near Term ◽  
Intermediate Disturbances

Intermediate disturbances are an important component of many forest disturbance regimes, with effects on canopy structure and related functions that are highly dependent on the nature and intensity of the perturbation. Ice storms are an important disturbance mechanism in temperate forests that often result in moderate-severity, diffuse canopy damage. However, it has not previously been possible to distinguish the specific effect of ice storm intensity (as ice accretion) from predisturbance stand characteristics and physiographic factors. In this study, we utilized a novel experimental ice storm treatment to evaluate the effects of variable ice accretion levels on forest canopy structure. Our results verified significant impacts of ice storm disturbance on near-term canopy structural reorganization. Canopy openness, light transmission, and complexity increased significantly relative to predisturbance baselines and undisturbed controls. We documented variable impacts with disturbance intensity, as significant canopy changes largely occurred with ice accretion levels of ≥12.7 mm. Repeated ice storm disturbance (two consecutive years) had marginal, rather than compounding, effects on forest canopy structure. Our findings are relevant to understanding how ice storms can affect near-term forest canopy structural reorganization and ecosystem processes and add to a growing base of knowledge on the effects of intermediate disturbances on canopy structure.

Low-dose aspirin prevents age-related endothelial dysfunction in a mouse model of physiological aging

2008 ◽  
Vol 294 (4) ◽  
pp. H1562-H1570 ◽  
Author(s):  
Hélène Bulckaen ◽  
Gaétan Prévost ◽  
Eric Boulanger ◽  
Géraldine Robitaille ◽  
Valérie Roquet ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Dysfunction ◽  
Protective Effect ◽  
Structural Changes ◽  
Low Dose ◽  
Age Groups ◽  
Dose Aspirin ◽  
Age Related ◽  
Low Dose Aspirin ◽  
Old Mice

The age-related impairment of endothelium-dependent vasodilatation contributes to increased cardiovascular risk in the elderly. For primary and secondary prevention, aspirin can reduce the incidence of cardiovascular events in this patient population. The present work evaluated the effect of low-dose aspirin on age-related endothelial dysfunction in C57B/J6 aging mice and investigated its protective antioxidative effect. Age-related endothelial dysfunction was assessed by the response to acetylcholine of phenylephrine-induced precontracted aortic segments isolated from 12-, 36-, 60-, and 84-wk-old mice. The effect of low-dose aspirin was examined in mice presenting a decrease in endothelial-dependent relaxation (EDR). The effects of age and aspirin treatment on structural changes were determined in mouse aortic sections. The effect of aspirin on the oxidative stress markers malondialdehyde and 8-hydroxy-2′-deoxyguanosine (8-OhdG) was also quantified. Compared with that of 12-wk-old mice, the EDR was significantly reduced in 60- and 84-wk-old mice ( P < 0.05); 68-wk-old mice treated with aspirin displayed a higher EDR compared with control mice of the same age (83.9 ± 4 vs. 66.3 ± 5%; P < 0.05). Aspirin treatment decreased 8-OHdG levels ( P < 0.05), but no significant effect on intima/media thickness ratio was observed. The protective effect of aspirin was not observed when treatment was initiated in older mice (96 wk of age). It was found that low-dose aspirin is able to prevent age-related endothelial dysfunction in aging mice. However, the absence of this effect in the older age groups demonstrates that treatment should be initiated early on. The underlying mechanism may involve the protective effect of aspirin against oxidative stress.

scholarly journals Quantitative Ice Accretion Information from the Automated Surface Observing System

2007 ◽  
Vol 46 (9) ◽  
pp. 1423-1437 ◽  
Author(s):  
Charles C. Ryerson ◽  
Allan C. Ramsay
Keyword(s):  
United States ◽  
The United States ◽  
Ice Thickness ◽  
Ice Storm ◽  
Design Standards ◽  
Ice Storms ◽  
Ice Accumulation ◽  
Direct Measurements ◽  
Improved Design ◽  
Precipitation Events

Abstract Freezing precipitation is a persistent winter weather problem that costs the United States millions of dollars annually. Costs and infrastructure disruption may be greatly reduced by ice-storm warnings issued by the National Weather Service (NWS), and by the development of climatologies that allow improved design of infrastructure elements. However, neither the NWS nor developers of climatologies have had direct measurements of ice-storm accumulations as a basis for issuing warnings and developing storm design standards. This paper describes the development of an aviation routine/special weather report (METAR/SPECI) remark that will report quantitative ice thickness at over 650 locations during ice storms using new algorithms developed for the Automated Surface Observing System (ASOS). Characteristics of the ASOS icing sensor, a field program to develop the algorithms, tests of accuracy, application of the algorithms, and sources of error are described, as is the implementation of an ice-thickness METAR/SPECI remark. The algorithms will potentially allow freezing precipitation events to be tracked with regard to ice accumulation in near–real time as they progress across the United States.

scholarly journals Redefining lumbar spinal stenosis as a developmental syndrome: an MRI-based multivariate analysis of findings in 709 patients throughout the 16- to 82-year age spectrum

2018 ◽  
Vol 29 (6) ◽  
pp. 654-660 ◽  
Author(s):  
Sameer Kitab ◽  
Bryan S. Lee ◽  
Edward C. Benzel
Keyword(s):  
Multivariate Analysis ◽  
Spinal Stenosis ◽  
Lumbar Spinal Stenosis ◽  
Structural Changes ◽  
Age Cohorts ◽  
Age Related ◽  
Management Approaches ◽  
Definition Of ◽  
Lumbar Spinal ◽  
Lower Lumbar

OBJECTIVEUsing an imaging-based prospective comparative study of 709 eligible patients that was designed to assess lumbar spinal stenosis (LSS) in the ages between 16 and 82 years, the authors aimed to determine whether they could formulate radiological structural differences between the developmental and degenerative types of LSS.METHODSMRI structural changes were prospectively reviewed from 2 age cohorts of patients: those who presented clinically before the age of 60 years and those who presented at 60 years or older. Categorical degeneration variables at L1–S1 segments were compared. A multivariate comparative analysis of global radiographic degenerative variables and spinal dimensions was conducted in both cohorts. The age at presentation was correlated as a covariable.RESULTSA multivariate analysis demonstrated no significant between-groups differences in spinal canal dimensions and stenosis grades in any segments after age was adjusted for. There were no significant variances between the 2 cohorts in global degenerative variables, except at the L4–5 and L5–S1 segments, but with only small effect sizes. Age-related degeneration was found in the upper lumbar segments (L1–4) more than the lower lumbar segments (L4–S1). These findings challenge the notion that stenosis at L4–5 and L5–S1 is mainly associated with degenerative LSS.CONCLUSIONSIntegration of all the morphometric and qualitative characteristics of the 2 LSS cohorts provides evidence for a developmental background for LSS. Based on these findings the authors propose the concept of LSS as a developmental syndrome with superimposed degenerative changes. Further studies can be conducted to clarify the clinical definition of LSS and appropriate management approaches.

scholarly journals Garlic Extract: Inhibition of Biochemical and Biophysical Changes in Glycated HSA

2021 ◽  
Vol 11 (22) ◽  
pp. 11028
Author(s):  
Mohd W. A. Khan ◽  
Ahmed A. Otaibi ◽  
Arwa F. M. Alhumaid ◽  
Abdulmohsen K. D. Alsukaibi ◽  
Asma K. Alshamari ◽  
...  
Keyword(s):  
Structural Changes ◽  
Therapeutic Potential ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Garlic Extract ◽  
Diabetic Patients ◽  
Age Related ◽  
Health Complications ◽  
Biophysical Changes

Glycation of various biomolecules contributes to structural changes and formation of several high molecular weight fluorescent and non-fluorescent, advanced glycation end products (AGEs). AGEs and glycation are involved in various health complications. Synthetic medicines, including metformin, have several adverse effects. Natural products and their derivatives are used in the treatment of various diseases due to their significant therapeutic qualities. Allium sativum (garlic) is used in traditional medicines because of its antioxidant, anti-inflammatory, and anti-diabetic properties. This study aimed to determine the anti-glycating and AGEs inhibitory activities of garlic. Biochemical and biophysical analyses were performed for in vitro incubated human serum albumin (HSA) with 0.05 M of glucose for 1, 5, and 10 weeks. Anti-glycating and AGEs inhibitory effect of garlic was investigated in glycated samples. Increased biochemical and biophysical changes were observed in glycated HSA incubated for 10 weeks (G-HSA-10W) as compared to native HSA (N-HSA) as well as glycated HSA incubated for 1 (G-HSA-1W) and 5 weeks (G-HSA-5W). Garlic extract with a concentration of ≥6.25 µg/mL exhibited significant inhibition in biophysical and biochemical changes of G-HSA-10W. Our findings demonstrated that garlic extract has the ability to inhibit biochemical and biophysical changes in HSA that occurred due to glycation. Thus, garlic extract can be used against glycation and AGE-related health complications linked with chronic diseases in diabetic patients due to its broad therapeutic potential.

scholarly journals Kidney aging.Geriatric view

2021 ◽  
pp. 76-81
Author(s):  
L. I. Merkusheva ◽  
N. K. Runikhina ◽  
O. N. Tkacheva
Keyword(s):  
Chronic Kidney Disease ◽  
Renal Function ◽  
Kidney Disease ◽  
Structural Changes ◽  
Water Soluble ◽  
Older Age ◽  
Sodium Reabsorption ◽  
Tubular Atrophy ◽  
Age Related ◽  
Population Demographic

Individuals age >65 years old are the fastest expanding population demographic throughout the developed world. Consequently, more aged patients than before are receiving diagnoses of impaired renal function and nephrosclerosis. In this review, we examine these features of the aged kidney and explore the various validated and putative pathways contributing to the changes observed with aging. Senescence or normal physiologic aging portrays the expected age-related changes in the kidney as compared to chronic kidney disease (CKD) in some individuals. The microanatomical structural changes of the kidney with older age include a decreased number of functional glomeruli from an increased prevalence of nephrosclerosis (arteriosclerosis, glomerulosclerosis, and tubular atrophy with interstitialfibrosis), and to some extent, compensatory hypertrophy of remaining nephrons. Among the macroanatomical structural changes, older age associates with smaller cortical volume. There is reason to be concerned that the elderly are being misdiagnosed with CKD. In addition to the structural changes in the kidney associated with aging, physiological changes in renal function are also found in older adults, such as decreased glomerular filtration rate, vascular dysautonomia, altered tubular handling of creatinine, reduction in sodium reabsorption and potassium secretion, and diminished renal reserve. These alterations make aged individuals susceptible to the development of clinical conditions in response to usual stimuli that would otherwise be compensated for in younger individuals, including acute kidney injury, volume depletion and overload, disorders of serum sodium and potassium concentration, and toxic reactions to water -soluble drugs excreted by the kidneys. Additionally, the preservation with aging of a normal urinalysis, normal serum urea and creatinine values, erythropoietin synthesis, and normal phosphorus, calcium and magnesium tubular handling distinguishes decreased GFR due to normal aging from that due to chronic kidney disease.

scholarly journals Label-free imaging of age-related cardiac structural changes in non-human primates using multiphoton nonlinear microscopy

2021 ◽  
Author(s):  
Amara Khan ◽  
Fernanda Ramos-Gomes ◽  
Andrea Markus ◽  
Matthias Mietsch ◽  
Rabea Hinkel ◽  
...  
Keyword(s):  
Structural Changes ◽  
Nonlinear Microscopy ◽  
Label Free ◽  
Age Related

scholarly journals Summertime canopy albedo is sensitive to forest thinning

2013 ◽  
Vol 10 (9) ◽  
pp. 15373-15414 ◽  
Author(s):  
J. Otto ◽  
D. Berveiller ◽  
F.-M. Bréon ◽  
N. Delpierre ◽  
G. Geppert ◽  
...  
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Structural Changes ◽  
Near Infrared ◽  
Canopy Structure ◽  
Model Parameters ◽  
Transfer Model ◽  
Forest Thinning ◽  
Crown Volume ◽  
The Difference

Abstract. Despite an emerging body of literature linking canopy albedo to forest management, understanding of the process is still fragmented. We combined a stand-level forest gap model with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning, that is removing trees at a certain time during the forest rotation, on summertime canopy albedo. The effects of different forest species (pine, beech, oak) and four thinning strategies (light to intense thinning regimes) were examined. During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning on summertime canopy albedo. These trends continue until the end of the rotation where thinning explains up to 50% of the variance in near-infrared canopy albedo and up to 70% of the variance in visible canopy albedo. More intense thinning lowers the summertime shortwave albedo in the canopy by as much as 0.02 compared to unthinned forest. The structural changes associated with forest thinning can be described by the change in LAI in combination with crown volume. However, forests with identical canopy structure can have different summertime albedo values due to their location: the further north a forest is situated, the more the solar zenith angle increases and thus the higher is the summertime canopy albedo, independent of the wavelength. Despite the increase of absolute summertime canopy albedo values with latitude, the difference in canopy albedo between managed and unmanaged forest decreases with increasing latitude. Forest management thus strongly altered summertime forest albedo.

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