An architectural approach to the growth forms of Nothofagus pumilio (Nothofagaceae) along an altitudinal gradient

Botany ◽  
2010 ◽  
Vol 88 (8) ◽  
pp. 699-709 ◽  
Author(s):  
Marina Stecconi ◽  
Javier G. Puntieri ◽  
Daniel Barthélémy
Keyword(s):  
High Altitude ◽  
Altitudinal Gradient ◽  
Single Species ◽  
Main Axis ◽  
Branching Pattern ◽  
Nothofagus Pumilio ◽  
Growth Forms ◽  
Northern Patagonia ◽  
Low Altitude ◽  
Different Altitudes

Variations in the architecture and axis structure of different growth forms of Nothofagus pumilio (Poepp. et Endl.) Krasser (Nothofagaceae) were studied along an altitudinal gradient. We evaluated the primary growth and branching pattern of annual shoots belonging to the main axis categories (trunk, main branches, and secondary (short) branches) of four growth forms developed at different altitudes (1200–1600 m a.s.l.) in northern Patagonia: (i) low shrubs at the high-altitude timberline, (ii) high shrubs at high altitude, (iii) low trees at mid-altitude slopes, and (iv) high trees at low-altitude single-species forests. Shoot structure and branch distribution along shoots were similar for all axis categories and growth forms. Significant differences between axis categories were found regarding the sizes of shoots, which decreased from trunk to secondary/short branches. For each axis category, shoots of similar size differed between growth forms in stem slenderness and internode length. The extent of differentiation between axis categories is key in the structural distinction between growth forms of N. pumilio.

scholarly journals A Probabilistic Target Search Algorithm Based on Hierarchical Collaboration for Improving Rapidity of Drones

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2535 ◽  
Author(s):  
Il-Kyu Ha ◽  
You-Ze Cho
Keyword(s):  
High Altitude ◽  
Target Detection ◽  
Information Transfer ◽  
Search Algorithm ◽  
Search Time ◽  
Previous Method ◽  
Target Search ◽  
Low Altitude ◽  
Military Facilities ◽  
Different Altitudes

Finding a target quickly is one of the most important tasks in drone operations. In particular, rapid target detection is a critical issue for tasks such as finding rescue victims during the golden period, environmental monitoring, locating military facilities, and monitoring natural disasters. Therefore, in this study, an improved hierarchical probabilistic target search algorithm based on the collaboration of drones at different altitudes is proposed. This is a method for reducing the search time and search distance by improving the information transfer methods between high-altitude and low-altitude drones. Specifically, to improve the speed of target detection, a high-altitude drone first performs a search of a wide area. Then, when the probability of existence of the target is higher than a certain threshold, the search information is transmitted to a low-altitude drone which then performs a more detailed search in the identified area. This method takes full advantage of fast searching capabilities at high altitudes. In other words, it reduces the total time and travel distance required for searching by quickly searching a wide search area. Several drone collaboration scenarios that can be performed by two drones at different altitudes are described and compared to the proposed algorithm. Through simulations, the performances of the proposed algorithm and the cooperation scenarios are analyzed. It is demonstrated that methods utilizing hierarchical searches with drones are comparatively excellent and that the proposed algorithm is approximately 13% more effective than a previous method and much better compared to other scenarios.

EFFECT OF SEED SOURCE ON GROWTH OF GIANT WILDRYE (Elymus cinereus) AT TWO ELEVATIONS IN INTERIOR BRITISH COLUMBIA

1990 ◽  
Vol 70 (2) ◽  
pp. 551-554 ◽  
Author(s):  
J. W. HALL ◽  
D. G. STOUT ◽  
B. BROOKE
Keyword(s):  
British Columbia ◽  
High Altitude ◽  
Seedling Establishment ◽  
Dry Matter ◽  
Initial Growth ◽  
Growth Forms ◽  
Forage Crop ◽  
Reciprocal Transplants ◽  
Altitude Adaptation ◽  
Low Altitude

Giant wildrye (Elymus cinereus Scribn. & Merr.) plants grown from seed obtained at two altitudes (346, 930 m) were transplanted to two sites (346, 900 m) and observed for 3 yr. Plants from the low altitude source produced more dry matter at both sites. More plants from the low altitude source produced seed heads at the low altitude site but seed head production of plants from the two sources was similar at the high altitude site. Provided studies of germination, seedling establishment and initial growth at different elevations were favorable, seed from low altitude sources could be used indiscriminately for establishing stands of giant wildrye. This would greatly simplify the use of giant wildrye as a forage crop in areas where varying altitude was of concern.Key words: Elymus cinereus, altitude adaptation, growth forms, reciprocal transplants, ecotypes

Characterization Method of Radar for Air Surveillance Coverage

2014 ◽  
Vol 716-717 ◽  
pp. 944-948
Author(s):  
Wen Quan Wu ◽  
Shu Sen Tian ◽  
Tao Liu
Keyword(s):  
High Altitude ◽  
Quick Response ◽  
Detection Ability ◽  
Calculating Method ◽  
Detection Point ◽  
Projection Distance ◽  
Air Surveillance ◽  
Detection Coverage ◽  
Low Altitude ◽  
Different Altitudes

Aiming at the radar vertical detection coverage limitation given by manufacturing factories, this paper put forwards a new characterization method of radar’s air surveillance coverage: it is the projection distance of furthest detection point for different RCS targets at different altitudes, which can directly show radar’s quick response to the attack action launched by fighter. Then this paper gives the calculating method of coverage characterization method, and calculates radar detection coverage of typical medium-low altitude search. The result shows that the detection ability to penetration fighter is weak for high altitude and below 300m altitude, especially for the high altitude penetration stealth fighter.

scholarly journals Low-Altitude Boundary of Abies faxoniana Is More Susceptible to Long-Term Open-Top Chamber Warming in the Eastern Tibetan Plateau

2021 ◽  
Vol 12 ◽  
Author(s):  
Haifeng Song ◽  
Qingquan Han ◽  
Sheng Zhang
Keyword(s):  
High Altitude ◽  
Global Climate ◽  
Subalpine Forest ◽  
Nutrient Concentrations ◽  
Open Top Chamber ◽  
Soil P ◽  
Abies Faxoniana ◽  
Low Altitude ◽  
Different Altitudes

With global climate change, for evaluating warming effect on subalpine forest distribution, the substantial effects of long-term warming on tree growth and soil nutrients need to be explored. In this study, we focused on different responses in the boundaries of trees and soils to warming. Using the open-top chamber (OTC), a 10-year artificial warming experiment was conducted to evaluate the impacts of warming on Abies faxoniana at three different altitudes. We determined metabolites and nutrient concentrations in needles of A. faxoniana and characterized the soil chemistries. Many kinds of sugars, amino acids, and organic acids showed higher contents at high altitude (3,500 m) compared with low altitude (2,600 m), which could have been due to the temperature differences. Warming significantly decreased needle sugar and amino acid concentrations at high altitude but increased them at low altitude. These results indicated contrasting physiological and metabolic responses of A. faxoniana to long-term warming at different altitudes. Furthermore, we found that OTC warming significantly increased the concentrations of soil extractable sodium, aluminum (Al), and manganese (Mn), while decreased potassium (K) and phosphorus (P) concentrations and pH values at low altitude rather than at middle (3,000 m) or high altitude. The soil carbon and nitrogen contents were increased only at the middle altitude. In A. faxoniana at low altitudes, more mineral nutrients iron, K, and P were demand, and a mass of Al, Mn, and zinc was accumulated under warming. Soil P limitation and heavy metals accumulation are disadvantageous for trees at low altitudes with warming. Therefore, compared with high altitudes, A. faxoniana growing at low boundary in alpine regions is expected to be more susceptible to warming.

scholarly journals Above-ground and Below-ground Biomass situation of Milke-Jaljale Rangeland at Different Altitudinal Gradient

Our Nature ◽  
1970 ◽  
Vol 9 (1) ◽  
pp. 107-111
Author(s):  
D.K. Limbu ◽  
M. Koirala
Keyword(s):  
Climate Change ◽  
High Altitude ◽  
Altitudinal Gradient ◽  
Plant Density ◽  
Above Ground Biomass ◽  
Carbon Reduction ◽  
Ground Biomass ◽  
Harvesting Method ◽  
Below Ground ◽  
Low Altitude

Rangeland conservation has been increasingly interested for carbon reduction and mitigation of climate change, because of carbon storage. Thus, biomass of the rangeland remains pivotal regarding carbon sequestration on rangeland. Present study was conducted in high altitude rangeland at Jaljale (4000 m), Gorujure (3500 m) and Milke (3000 m) on September, 2010 with an objective to estimate rangeland biomass following the total harvesting method. Result revealed that biomass of high altitude rangeland has relatively high value (1.50 t/ha for both above ground biomass and 43.48 t/ha for below ground biomass) compared to low altitude rangeland (0.35 t/ha for above ground biomass and 16.93 t/ha for below ground biomass). Similarly, monocot plant density play crucial role for biomass contribution of rangeland.DOI: http://dx.doi.org/10.3126/on.v9i1.5740

scholarly journals Acacia honey from different altitudes: total phenols and flavonoids, laser-induced fluorescence (LIF) spectra, and anticancer activity

2020 ◽  
Vol 48 (8) ◽  
pp. 030006052094345
Author(s):  
Moammed Elimam Ahamed Mohammed ◽  
Ali A Shati ◽  
Mohammad Y Alfaifi ◽  
Serag Eldin I Elbehairi ◽  
Mohammed Ali Alshehri ◽  
...  
Keyword(s):  
High Altitude ◽  
Anticancer Activity ◽  
Human Cancer ◽  
Laser Induced Fluorescence ◽  
Total Phenols ◽  
Mcf7 Cells ◽  
Human Cancer Cell Lines ◽  
Acacia Honey ◽  
Low Altitude ◽  
Different Altitudes

Objective To investigate Acacia honey from different altitudes regarding total phenols and flavonoids, laser-induced fluorescence (LIF) spectra and anticancer activity against human cancer cell lines. Methods Anticancer activity was investigated using sulforhodamine B cytotoxicity assays in the following human cancer cell lines: HCT116 (colon); MCF7 (breast), and HepG2 (liver). Total phenols and flavonoids were measured using spectrophotometric methods and LIF was used to differentiate between low and high-altitude honey. Results The LIF spectra differed between low and high-altitude Acacia honey. High altitude Acacia honey was characterized by significantly lower total phenol content (81.47 ± 1.25 mg gallic acid equivalent [GAE]/100 g) and increased total flavonoids (10.63 ± 0.53 mg quercetin equivalent [QE]/100 g) versus low altitude Acacia honey (91.33 ± 0.96 mg GAE/100 g and 8.78 ± 0.23 mg QE/100 g, respectively). Low altitude Acacia honey displayed increased IC50 values against HCT116 and MCF7 cells (264.17 ± 10.5 and 482.65 ± 20.3 µg/ml, respectively) versus high altitude Acacia honey (117.99 ± 12.7 and 189.82 ± 15.8 µg/ml, respectively). Conclusions High altitude Acacia honey had significantly more effective anticancer activity against HCT116 and MCF7 cells compared with low altitude honey.

scholarly journals Effect of High-Altitude Environment on Driving Safety: A Study on Drivers’ Mental Workload, Situation Awareness, and Driving Behaviour

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xinyan Wang ◽  
Wu Bo ◽  
Weihua Yang ◽  
Suping Cui ◽  
Pengzi Chu
Keyword(s):  
High Altitude ◽  
Situation Awareness ◽  
Mental Workload ◽  
Mediating Effect ◽  
Driving Safety ◽  
Risky Driving ◽  
Driving Behaviour ◽  
Driving Risk ◽  
Low Altitude ◽  
The Relationship

This study aims to analyze the effect of high-altitude environment on drivers’ mental workload (MW), situation awareness (SA), and driving behaviour (DB), and to explore the relationship among those driving performances. Based on a survey, the data of 356 lowlanders engaging in driving activities at Tibetan Plateau (high-altitude group) and 341 lowlanders engaging in driving activities at low altitudes (low-altitude group) were compared and analyzed. The results suggest that the differences between the two groups are noteworthy. Mental workload of high-altitude group is significantly higher than that of low-altitude group, and their situation awareness is lower significantly. The possibility of risky driving behaviours for high-altitude group, especially aggressive violations, is higher. For the high-altitude group, the increase of mental workload can lead to an increase on aggressive violations, and the situation understanding plays a full mediating effect between mental workload and aggressive violations. Measures aiming at the improvement of situation awareness and the reduction of mental workload can effectively reduce the driving risk from high-altitude environment for lowlanders.

scholarly journals Effect of high altitude on human placental amino acid transport

2020 ◽  
Vol 128 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Owen. R. Vaughan ◽  
Fredrick Thompson ◽  
Ramón. A. Lorca ◽  
Colleen G. Julian ◽  
Theresa L. Powell ◽  
...  
Keyword(s):  
Birth Weight ◽  
Amino Acid ◽  
High Altitude ◽  
Sea Level ◽  
Amino Acid Transport ◽  
Acid Uptake ◽  
Acid Transport ◽  
Transport Capacity ◽  
System A ◽  
Low Altitude

Women residing at high altitudes deliver infants of lower birth weight than at sea level. Birth weight correlates with placental system A-mediated amino acid transport capacity, and severe environmental hypoxia reduces system A activity in isolated trophoblast and the mouse placenta. However, the effect of high altitude on human placental amino acid transport remains unknown. We hypothesized that microvillous membrane (MVM) system A and system L amino acid transporter activity is lower in placentas of women living at high altitude compared with low-altitude controls. Placentas were collected at term from healthy pregnant women residing at high altitude (HA; >2,500 m; n = 14) or low altitude (LA; <1,700 m; n = 14) following planned, unlabored cesarean section. Birth weight, but not placenta weight, was 13% lower in HA pregnancies (2.88 ± 0.11 kg) compared with LA (3.30 ± 0.07 kg, P < 0.01). MVM erythropoietin receptor abundance, determined by immunoblot, was greater in HA than in LA placentas, consistent with lower placental oxygen levels at HA. However, there was no effect of altitude on MVM system A or L activity, determined by Na+-dependent [14C]methylaminoisobutyric acid uptake and [3H]leucine uptake, respectively. MVM abundance of glucose transporters (GLUTs) 1 and 4 and basal membrane GLUT4 were also similar in LA and HA placentas. Low birth weights in the neonates of women residing at high altitude are not a consequence of reduced placental amino acid transport capacity. These observations are in general agreement with studies of IUGR babies at low altitude, in which MVM system A activity is downregulated only in growth-restricted babies with significant compromise. NEW & NOTEWORTHY Babies born at high altitude are smaller than at sea level. Birth weight is dependent on growth in utero and, in turn, placental nutrient transport. We determined amino acid transport capacity in placentas collected from women resident at low and high altitude. Altitude did not affect system A amino acid transport across the syncytiotrophoblast microvillous membrane, suggesting that impaired placental amino acid transport does not contribute to reduced birth weight in this high-altitude population.

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