Analyse écologique des peuplements de frêne noir (Fraxinus nigra) des rives du lac Duparquet, nord-ouest du Québec

1992 ◽  
Vol 70 (11) ◽  
pp. 2294-2302 ◽  
Author(s):  
Jacques Tardif ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Hierarchical Classification ◽  
Early Summer ◽  
Plant Distribution ◽  
Vegetation Types ◽  
Factors Affecting ◽  
Fraxinus Nigra ◽  
Main Factors ◽  
Speckled Alder ◽  
Black Ash

Spring and early summer flood is one of the main factors affecting the dynamics of black ash (Fraxinus nigra Marsh.) stands growing on lake floodplains in the boreal forest. The effect of flooding on the vegetation was studied in five stands on the shore of Lake Duparquet in Abitibi, northwestern Quebec. Divisive hierarchical classification analysis (Twinspan) revealed the existence of four different vegetation types: (i) black ash – speckled alder (Alnus rugosa) – bog willow (Salix pedicellaris), (ii) black ash – balsam poplar (Populus balsamifera) – ostrich fern (Matteuccia struthiopteris), (iii) black ash – pussy willow (Salix discolor) – sensitive fern (Onoclea sensibilis), and (iv) black ash – speckled alder – sensitive fern. Detrended correspondance analysis (Decorana) shows that elevation and drainage are the main factors affecting plant distribution and dynamics. Geomorphology also plays a major role in the way each stand responds to flooding. For each of the vegetation types studied, black ash shows a particular regeneration pattern and sexual regeneration tends to become less frequent with increasing exposure to flooding. Finally, the strong sexual regeneration and the youth of the populations found in the most elevated sites could be related to a possible alteration of the flood regime. Key words: Fraxinus nigra Marsh., flooding, boreal forest, floodplain, ecological gradiant, regeneration.

Gradient analysis of Larix laricina dominated wetlands in Canada's southeastern boreal forest

2001 ◽  
Vol 79 (4) ◽  
pp. 444-456 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Abies Balsamea ◽  
Hierarchical Classification ◽  
Canopy Cover ◽  
Larix Laricina ◽  
Betula Papyrifera ◽  
Kalmia Angustifolia ◽  
Fraxinus Nigra ◽  
Hierarchical Classification Analysis ◽  
Substrate Ph

With the objective of understanding how vegetation was structured in four Larix laricina (Du Roi) K. Koch dominated wetlands in north-western Quebec, 186 point-centred quarters were sampled in four stands. For each point, both biotic and abiotic variables were collected and species cover was recorded. Divisive hierarchical classification analysis (Twinspan) identified nine vegetation clusters: i) Larix laricina & Spiraea alba, ii) Larix laricina & Kalmia angustifolia, iii) Larix laricina, Picea mariana & Alnus rugosa, iv) Larix laricina & Betula pumila, v) Thuja occidentalis & Trientalis borealis, vi) Abies balsamea & Betula papyrifera, vii) Fraxinus nigra & Onoclea sensibilis, viii) Alnus rugosa, and ix) Eleocharis smallii. Results of the canonical correspondence analyses indicated that the distribution of these clusters was mainly related to (i) distance from shore, (ii) shade (canopy cover), (iii) substrate nitrate concentration (in relation to the abundance of Kalmia angustifolia and Alnus rugosa), (iv) substrate pH (in relation to the abundance of Sphagnum spp.), and (v) substrate conductivity. Several characteristics of the water table also affected species distribution, including pH, depth, and carbon concentration. Further studies should address the effect of the presence of Kalmia angustifolia and Alnus rugosa on larch growth.Key words: larch, wetland, vegetation analysis, flooding, boreal forest.

Recent Rapid Climate Changes in Antarctic and their Influence on Low Diversity Ecosystems

2010 ◽  
Vol 17 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Katarzyna J. Chwedorzewska
Keyword(s):  
Environmental Variables ◽  
Climate Changes ◽  
Biological Significance ◽  
Global Changes ◽  
Factors Affecting ◽  
Low Diversity ◽  
Main Factors ◽  
The Antarctic ◽  
High Diversity ◽  
Temperature Water

ABSTRACTThe geographic position, astronomic factors (e.g. the Earth’s maximum distance from the Sun during winter), ice cover and altitude are the main factors affecting the climate of the Antarctic, which is the coldest place on Earth. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. Climate changes are occurring throughout Antarctica, affecting three major groups of environmental variables of considerable biological significance: temperature, water, UV-B radiation.Low diversity ecosystems are expected to be more vulnerable to global changes than high diversity ecosystems

Pitting Corrosion of Biomedical Titanium and Titanium Alloys: A Brief Review

2020 ◽  
Vol 16 ◽  
Author(s):  
Yu-Wei Cui ◽  
Liang-Yu Chen ◽  
Xin-Xin Liu
Keyword(s):  
Corrosion Resistance ◽  
Pitting Corrosion ◽  
Potential Temperature ◽  
Growth Stages ◽  
Factors Affecting ◽  
Ti Alloys ◽  
Pitting Corrosion Resistance ◽  
Superior Mechanical Properties ◽  
Good Biocompatibility ◽  
Main Factors

Abstract:: Thanks to their excellent corrosion resistance, superior mechanical properties and good biocompatibility, titanium (Ti) and Ti alloys are extensively applied in biomedical fields. Pitting corrosion is a critical consideration for the reliability of Ti and Ti alloys used in the human body. Therefore, this article focuses on the pitting corrosion of Ti and Ti alloys, which introduces the growth stages of pitting corrosion and its main influencing factors. Three stages, i.e. (1) breakdown of passive film, (1) metastable pitting, and (3) propagation of pitting, are roughly divided to introduce the pitting corrosion. As reviewed, corrosive environment, applied potential, temperature and alloy compositions are the main factors affecting the pitting corrosion of Ti and Ti alloys. Moreover, the pitting corrosion of different types Ti alloys are also reviewed to correlate the types of Ti alloys and the main factors of pitting corrosion. Roughly speaking, β-type Ti alloys have the best pitting corrosion resistance among the three types of Ti alloys.

FRAXINUS NIGRA, BLACK ASH

2014 ◽  
pp. 898-899
Author(s):  
Henry John Elwes ◽  
Augustine Henry
Keyword(s):  
Fraxinus Nigra ◽  
Black Ash

scholarly journals Measuring the Efficiency of Football Clubs Using Data Envelopment Analysis: Empirical Evidence From Spanish Professional Football

SAGE Open ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215824402198925
Author(s):  
Isidoro Guzmán-Raja ◽  
Manuela Guzmán-Raja
Keyword(s):  
Data Envelopment Analysis ◽  
High Efficiency ◽  
Sport Performance ◽  
Data Envelopment ◽  
Professional Football ◽  
Efficiency Measure ◽  
Factors Affecting ◽  
Football Clubs ◽  
Main Factors ◽  
Using Data

Professional football clubs have a special characteristic not shared by other types of companies: their sport performance (on the field) is important, in addition to their financial performance (off the field). The aim of this paper is to calculate an efficiency measure using a model that combines performance (sport and economic) based on data envelopment analysis (DEA). The main factors affecting teams’ efficiency levels are investigated using cluster analysis. For a sample of Spanish football clubs, the findings indicate that clubs achieved a relatively high efficiency level for the period studied, and that the oldest teams with the most assets had the highest efficiency scores. These results could help club managers to improve the performance of their teams.

scholarly journals Enzymatic Process for Cystoseira barbata Valorization: Ethanol Production and Additional By-Products

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 741
Author(s):  
Doinita-Roxana Cioroiu Tirpan ◽  
Ancaelena Eliza Sterpu ◽  
Claudia Irina Koncsag ◽  
Alina Georgiana Ciufu ◽  
Tănase Dobre
Keyword(s):  
Ethanol Production ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Product Yield ◽  
Liquid Ratio ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Cystoseira Barbata ◽  
Main Factors ◽  
Process Factors

The aim of this study is to evaluate the potential of dried Cystoseira barbata alga for ethanol production through alcoholic fermentation. The influence of the main factors affecting the fermentation are studied in the frame of a 23 factorial experimental plan. The main factors influencing the process are the fermentation temperature (t from 25 °C to 35 °C), the solid to liquid ratio (S/L from 0.040 g/g to 0.080 g/g), and the cellulase ratio (R from 8 U/g d.m to 16 U/g d.m.). The maximum volatile compounds yield of 0.2808 g/g d.m and ethanol yield of 0.0158 g/g d.m were favored by the following experimental conditions: process temperature of 35 °C, solid to liquid ratio of 0.0415, and enzyme ratio of 16 U/g d.m. A statistical model was used to correlate the product yield with the process factors. Additionally, 19 interesting bioactive compounds were found in the enzymatic hydrolysis and alcoholic fermentation broths which seem likely to maintain natural defence mechanisms against diseases and physical disorders.

scholarly journals The role of serum β-trophin and endostatin in patients with polycystic ovary syndrome: Are they correlated?

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Gong ◽  
Aikmu Bilixzi ◽  
Xinmei Wang ◽  
Yanli Lu ◽  
Li Wan ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Influencing Factors ◽  
Polycystic Ovary ◽  
Pearson Correlation ◽  
Healthy Controls ◽  
Newly Diagnosed ◽  
Ovary Syndrome ◽  
Factors Affecting ◽  
Main Factors

Abstract Background It’s necessary to investigate the serum β-trophin and endostatin (ES) level and its influencing factors in patients with newly diagnosed polycystic ovary syndrome (PCOS). Methods Newly diagnosed PCOS patients treated in our hospital were selected, and healthy women who took physical examination during the same period as healthy controls. We detected and compared the related serum indicators between two groups, Pearson correlation were conducted to identify the factors associated with β-trophin and ES, and the influencing factors of β-trophin and ES were analyzed by logistic regression. Results A total of 62 PCOS patients and 65 healthy controls were included. The BMI, WHI, LH, FSH, TT, FAI, FBG, FINS, HOMA-IR, TC, TG, LDL, ES in PCOS patients were significantly higher than that of healthy controls, while the SHBG and HDL in PCOS patients were significantly lower than that of healthy controls (all p < 0.05). β-trophin was closely associated with BMI (r = 0.427), WHR (r = 0.504), FBG (r = 0.385), TG (r = 0.405) and LDL (r = 0.302, all p < 0.05), and ES was closely associated with BMI (r = 0.358), WHR (r = 0.421), FBG (r = 0.343), TC (r = 0.319), TG (r = 0.404, all p < 0.05). TG, BMI, WHR and FBG were the main factors affecting the serum β-trophin levels (all p < 0.05). FBG, TC and BMI were the main factors affecting the serum ES levels (all p < 0.05). The TG, β-trophin, ES level in PCOS patients with insulin resistance (IR) were significantly higher than that of those without IR (all p < 0.05). Conclusion Increased β-trophin is closely associated with increased ES in patients with PCOS, which may be the useful indicators for the management of PCOS.

Laboratory Tests on Engineering Properties of Wind-Blown Sand

2012 ◽  
Vol 170-173 ◽  
pp. 706-709
Author(s):  
Zhao Lin Jia ◽  
Shu Wang Yan ◽  
Zhi Liang Huo
Keyword(s):  
Water Content ◽  
Laboratory Tests ◽  
Fine Sand ◽  
Engineering Properties ◽  
Grain Composition ◽  
Factors Affecting ◽  
Compaction Curve ◽  
Main Factors ◽  
Dry And Wet Conditions ◽  
Compaction Properties

By means of laboratory tests and theoretical calculation, the physical, mechanical properties and compaction mechanism of the wind-blown sand are studied to deal with the problem of how to use the wind-blown sand as roadbed materials. It is revealed that water content doesn’t affect the compressibility and the shear strength of the wind-blown sand obviously and the wind-blown sand can be compacted both in dry and wet conditions. The compaction curve of the ordinary fine sand is consistent with that of wind-blown sand and the main factors affecting the compaction properties are the grain composition, water content and compaction work.

Study of hotmelt adhesives used in food packaging multilayer laminates. Evaluation of the main factors affecting migration to food

2011 ◽  
Vol 21 (2) ◽  
pp. 420-431 ◽  
Author(s):  
Paula Vera ◽  
Margarita Aznar ◽  
Peter Mercea ◽  
Cristina Nerín
Keyword(s):  
Food Packaging ◽  
Factors Affecting ◽  
Main Factors

A study of the main factors affecting Ni–MH battery activation

1999 ◽  
Vol 293-295 ◽  
pp. 799-803 ◽  
Author(s):  
C.Z Yu ◽  
G.J Yan ◽  
W.H Lai ◽  
Q.H Dong
Keyword(s):  
Factors Affecting ◽  
Main Factors ◽  
Mh Battery
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