Perte de compétitivité par adaptation au milieu physique: cas du Salix uva-ursi dans la toundra du Nouveau-Québec

1988 ◽  
Vol 66 (8) ◽  
pp. 1532-1538 ◽  
Author(s):  
Lucie Maillette ◽  
Luc Bélisle ◽  
Maurice K. Seguin
Keyword(s):  
Competitive Ability ◽  
Slow Growth ◽  
Temporal Variations ◽  
The Other ◽  
Apparent Contradiction ◽  
Trade Off ◽  
Physical Conditions ◽  
Alpine Species ◽  
Slow Growing ◽  
Harsh Conditions

Plant species of wind-exposed tundra sites are usually low lying and slow growing. Such a combination probably reduces competitive ability, perhaps to the point of limiting wind-tolerant species to sites with little or no competition, i.e., the most exposed sites, as if there were a trade-off between adaptation to physical conditions and competitive ability. That hypothesis was tested with Salix uva-ursi Pursh, an arctic–alpine species common on windy sites in northern Quebec. Salix uva-ursi increases in abundance with exposure to wind, contrary to other species, but tolerates, even "prefers", the physical conditions found in sheltered sites. These two observations support the idea that interspecific competition limits the distribution of S. uva-ursi. However, the vigour of S. uva-ursi (number and size of shoots) is greatest in the sheltered sites, where the other species are more numerous and vigourous. This apparent contradiction between distribution and vigour could find an explanation in the temporal variations in climate. Under favourable conditions, prostrate and slow growth would be a handicap to S. uva-ursi, compared with other species, whereas under harsh conditions, species sensitive to wind and cold would suffer more than S. uva-ursi. [Translated by the journal]

Growth and carcass composition of second-cross lambs. 1. Effect of sex and growth path on pre- and post-slaughter estimates of carcass composition

2001 ◽  
Vol 52 (8) ◽  
pp. 859 ◽  
Author(s):  
D. G. Hall ◽  
A. R. Gilmour ◽  
N. M. Fogarty ◽  
P. J . Holst ◽  
D. L. Hopkins
Keyword(s):  
Seasonal Variation ◽  
Slow Growth ◽  
Fast Rate ◽  
Carcass Composition ◽  
The Other ◽  
Carcass Weight ◽  
Growth Path ◽  
Slaughter Weight ◽  
Slow Growing ◽  
Total Tissue

Carcass composition was estimated for 2316 second-cross lambs sired by 20 Poll Dorset rams over 2 years. The lambs were separated into ewes or cryptorchids at weaning with half of each sex group grown at a fast rate from weaning to slaughter at 40 kg liveweight for ewes or 48 kg for cryptorchids. The other half of each sex group was grown at a slower rate to the same slaughter weight 10–13 weeks later. Cryptorchids had fat scores about 0.4–1 unit lower and ultrasound C fat depths (45 mm from the mid-line over the 12th rib) about 0.8–1.3 mm less than ewes at the same liveweight. The carcass measures unequivocally showed that at the same carcass weight, fast-growing lambs were fatter than slow-growing lambs in both years and for both sexes. The average differences were 1.5 mm GR (total tissue depth 110 mm from the mid-line of the carcass over the 12th rib) and 1.4 mm C fat depth. Fat measurements on live lambs showed fast-growth cryptorchids were fatter than slow-growth cryptorchids; however, results for ewes were inconclusive. Slow growth to increase leanness needs to be evaluated against prevailing costs of lamb production and seasonal variation in prices. The correlations among and between live measures and carcass measurements of fatness were relatively low. The highest live to carcass R 2 values were ultrasound C fat depth with carcass C fat depth (0.36) and with the AUS-MEAT probe GR (0.34). There is a need to identify the best live lamb predictors of carcass composition.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

Soviet Policy Toward Germany During the Russo-Polish War, 1920

Slavic Review ◽  
1976 ◽  
Vol 35 (4) ◽  
pp. 665-682 ◽  
Author(s):  
Robert Himmer
Keyword(s):  
Weimar Republic ◽  
The Other ◽  
Apparent Contradiction ◽  
German Government ◽  
Soviet Policy ◽  
Economic Problems ◽  
Red Army ◽  
History Of ◽  
Communist Revolution ◽  
Soviet Russia

The Russo-Polish War occasioned some of the most anxious moments in the history of relations between Soviet Russia and the Weimar Republic. Within Germany, the advance of the Red Army toward Warsaw in 1920 aroused strong, but contradictory emotions. First, it led many Germans to anticipate the destruction of Poland and to hope for the restoration of the Reich’s former eastern territories. Simultaneously, however, the westward Russian march raised fears of the invasion of Germany by Bolshevik forces. Within Russia, a similar dichotomy of views about Germany existed. On one hand, the German government was considered a hostile, though negligible and temporary—a Communist revolution there was thought imminent—factor in Russia’s situation. On the other, Germany was held important enough to Russia that serious proposals of a far-reaching alliance against Poland and the Entente were made to her. The former view rested on a fundamentally optimistic assessment of Russia’s prospects; the latter, on a sober one. Grounds for concern were afforded by the Soviet Republic’s grave economic problems and by worry about whether the weary Red Army could defeat Pilsudski’s forces, whose offensive capacity had been demonstrated by their capture of Kiev in May 1920. If Germany, which had had military forces in the field against the Bolsheviks only a year before, should actively assist the Poles, Russia’s situation could be appreciably worsened. Surprisingly, therefore, although there are several recent, excellent studies of Soviet-Polish affairs and the Russo-Polish War, and a voluminous literature on relations between the Soviets and the Weimar Republic, little attention has been paid to Soviet policy toward Germany during the conflict with Poland. To explain that policy, and its apparent contradiction, is the purpose of this article.

Identifying opportunities for value chain development in the Kenyan coffee sector

2018 ◽  
Vol 47 (2) ◽  
pp. 150-159 ◽  
Author(s):  
Emerta Aragie
Keyword(s):  
Value Chain ◽  
Export Performance ◽  
Export Subsidy ◽  
The Other ◽  
Cash Crop ◽  
Trade Off ◽  
Cash Crops ◽  
Standard Value ◽  
Coffee Sector ◽  
Productivity Gains

By developing a model that describes the Kenyan coffee value chain, this study evaluates opportunities emanating from four scenarios representing productivity gains in the various value chain stages of the coffee sector and additional three scenarios reflecting shifts in market situations. Results show that productivity-enhancing policies have stronger effects on coffee output and export performance if they target the milling stage of the value chain. Export subsidy and favourable external marketing conditions also have stronger effects, distributed comparably across the various value chain stages. We, however, found that these gains in the coffee sector come at the expense of other cash crops such as cotton, tea, sugar and tobacco. The approach followed in this study is relevant as this trade-off between coffee and the other cash crop sectors may not be visibly shown using standard value chain approaches.

Practical Aspects of Propulsion Shaft Alignment

2021 ◽  
Author(s):  
Kyriakos Avgouleas ◽  
Emmanouil Sarris ◽  
George Gougoulidis
Keyword(s):  
Cost Effectiveness ◽  
Numerical Model ◽  
High Speed ◽  
The Other ◽  
Technical Literature ◽  
Trade Off ◽  
Fea Model ◽  
Shaft Alignment ◽  
Alignment Strategy ◽  
Potential Damage

The economical and operational implications of poor alignment are indisputable for the propulsion shafting system of a commercial vessel. This holds true for naval vessels as well, although far less documented in the technical literature. This paper addresses some of the challenges associated with the proper alignment of a high-speed naval craft, which has been in service for many years. Laser bore-sighting was performed on a Guided Missile Fast Patrol Boat resting on a docking cradle. The measured bearing offsets were input to a FEA model of the shafting system to calculate bearing reactions and detect potential misalignment issues. Subsequent decisions regarding corrective measures take into account the results computed by the numerical model, experience from sister ships, the available documentation from the building yard and several other factors which are discussed in the paper. The solutions proposed are targeted towards a balanced trade-off between cost effectiveness and out-of-service time on one hand, and the risk of potential damage from misalignment on the other hand, which would seriously disrupt the ship’s operational availability. Practical aspects and lessons identified in the process are also presented, which demonstrate the distinct differences in alignment strategy of a high-speed naval craft compared to a typical commercial vessel.

COMPUTING THE RUPTURE DEGREE IN COMPOSITE GRAPHS

2010 ◽  
Vol 21 (03) ◽  
pp. 311-319 ◽  
Author(s):  
AYSUN AYTAC ◽  
ZEYNEP NIHAN ODABAS
Keyword(s):  
Complete Graph ◽  
Connected Graph ◽  
The Other ◽  
Trade Off ◽  
Number Of Components ◽  
Np Complete ◽  
Work Done ◽  
Better Than

The rupture degree of an incomplete connected graph G is defined by [Formula: see text] where w(G - S) is the number of components of G - S and m(G - S) is the order of a largest component of G - S. For the complete graph Kn, rupture degree is defined as 1 - n. This parameter can be used to measure the vulnerability of a graph. Rupture degree can reflect the vulnerability of graphs better than or independent of the other parameters. To some extent, it represents a trade-off between the amount of work done to damage the network and how badly the network is damaged. Computing the rupture degree of a graph is NP-complete. In this paper, we give formulas for the rupture degree of composition of some special graphs and we consider the relationships between the rupture degree and other vulnerability parameters.

scholarly journals A Competitive Ratio for Quantifying Competition Between Intercrops

1980 ◽  
Vol 16 (2) ◽  
pp. 117-125 ◽  
Author(s):  
R. W. Willey ◽  
M. R. Rao
Keyword(s):  
Competitive Ratio ◽  
Competitive Ability ◽  
Maximum Yield ◽  
The Other ◽  
Competitive Balance ◽  
Crop Competition

SUMMARYA simple competitive ratio (CR) is proposed as a measure of intercrop competition, to indicate the number of times by which one component crop is more competitive than the other. Intercropping data show that this CR term could be useful in (i) comparing the competitive ability of different crops, (ii) measuring competitive changes within a given combination, (iii) identifying which plant characters are associated with competitive ability, and (iv) determining what competitive balance between components is most likely to give maximum yield advantages.

scholarly journals Partner Uncertainty and the Dynamic Boundary of the Firm

2017 ◽  
Vol 9 (4) ◽  
pp. 277-302 ◽  
Author(s):  
Thomas Hellmann ◽  
Veikko Thiele
Keyword(s):  
Asset Specificity ◽  
The Other ◽  
Trade Off ◽  
Specific Investments ◽  
Dynamic Boundary ◽  
Ex Post ◽  
Ex Ante

We develop a new theory of the dynamic boundary of the firm where asset owners may want to change partners ex post. We identify a fundamental trade-off between (i) a “displacement externality” under non-integration, where a partner leaves a relationship even though his benefit is worth less than the loss to the displaced partner, and (ii) a “retention externality” under integration, where a partner inefficiently retains the other. With more asset specificity, displacement externalities matter more and retention externalities less, so that integration becomes more attractive. Wealth can resolve ex post inefficient partner arrangements, but may weaken ex ante incentives for specific investments. (JEL D21, D23, D25, D62, D86, G31)

The effect of leguminous plant species onCallosobruchus maculatus(Coleoptera: Bruchidae) and its egg parasitoidUscana lariophaga(Hymenoptera: Trichogrammatidae)

1998 ◽  
Vol 88 (1) ◽  
pp. 93-99 ◽  
Author(s):  
A. van Huis ◽  
M. de Rooy
Keyword(s):  
Sex Ratio ◽  
Plant Species ◽  
Nutritional Quality ◽  
Development Time ◽  
Callosobruchus Maculatus ◽  
Egg Parasitoid ◽  
The Other ◽  
Leguminous Plant ◽  
Trade Off ◽  
Storage Pest

AbstractThe performance of the egg parasitoidUscana lariophagaSteffan was studied when reared on eggs of the bruchid storage pest,Callosobruchus maculatus(Fabricius) developing in seeds of cowpea, chickpea and pigeonpea. The beetle laid more and larger eggs on pigeonpea than on cowpea and chickpea, indicating that there was not a trade-off between number and size of the eggs. The bruchid larvae reared on pigeonpea exhibited a longer development time and a higher mortality than those reared on cowpea and chickpea. The resulting males weighed less than those reared on cowpea and chickpea. The trichogrammatidU. lariophagaparasitized more eggs whenC. maculatuswas reared on chickpea than when reared on the other hosts. Parasitoid larvae developed slowest and had the highest mortality in eggs ofC. maculatusreared on pigeonpea compared to those reared on cowpea and chickpea; the sex ratio (% of females) of the resulting adults was also higher. The high mortality and long development time ofC. maculatusreared on pigeonpea indicated that this legume was less favourable toC. maculatusthan chickpea or cowpea. This was probably also true for the parasitoid since the mortality was higher and development longer in eggs ofC. maculatusreared on pigeonpea compared to those reared on cowpea and chickpea. Therefore, when host eggs were larger and of lower nutritional quality, the proportion of female egg parasitoids was greater.

scholarly journals Plasmodium infection decreases fecundity and increases survival of mosquitoes

2012 ◽  
Vol 279 (1744) ◽  
pp. 4033-4041 ◽  
Author(s):  
J. Vézilier ◽  
A. Nicot ◽  
S. Gandon ◽  
A. Rivero
Keyword(s):  
Life History ◽  
Insecticide Resistance ◽  
Life History Traits ◽  
Experimental System ◽  
Adaptive Strategy ◽  
Genetic Variations ◽  
The Other ◽  
Plasmodium Infection ◽  
Trade Off ◽  
The One

Long-lived mosquitoes maximize the chances of Plasmodium transmission. Yet, in spite of decades of research, the effect of Plasmodium parasites on mosquito longevity remains highly controversial. On the one hand, many studies report shorter lifespans in infected mosquitoes. On the other hand, parallel (but separate) studies show that Plasmodium reduces fecundity and imply that this is an adaptive strategy of the parasite aimed at redirecting resources towards longevity. No study till date has, however, investigated fecundity and longevity in the same individuals to see whether this prediction holds. In this study, we follow for both fecundity and longevity in Plasmodium- infected and uninfected mosquitoes using a novel, albeit natural, experimental system. We also explore whether the genetic variations that arise through the evolution of insecticide resistance modulate the effect of Plasmodium on these two life-history traits. We show that (i) a reduction in fecundity in Plasmodium- infected mosquitoes is accompanied by an increase in longevity; (ii) this increase in longevity arises through a trade-off between reproduction and survival; and (iii) in insecticide-resistant mosquitoes, the slope of this trade-off is steeper when the mosquito is infected by Plasmodium (cost of insecticide resistance).

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