999 resultados para abelian varieties, integrable systems
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The institutionalisation of early retirement has become a universal feature of postwar industrial economies, though there are significant cross-national variations. This paper studies the impact of different types of welfare regimes, production systems and labour relations on early exit from work. After an analysis of the main trends, the paper discusses the costs and benefits of early retirement for the various actors — labour, capital and the state — at different levels. The paper outlines both the "pull” and "push” factors of early exit. It first compares the distinct welfare state regimes and private occupational pensions in their impact on early retirement. Then it looks at the labour-shedding strategies inherent to particular employment regimes, production systems and financial governance structures. Finally, the impact of particular industrial relations systems, and especially the role of unions is discussed. The paper finds intricate "institutional complementarities” between particular welfare states, production regimes and industrial relations systems, and these structure the incentives under which actors make decisions on work and retirement. The paper argues that the "collusion” between capital, labour and the state in pursuing early retirement is not merely following a labour-shedding strategy to ease mass unemployment, but also caused by the need for economic restructuration, the downsizing pressures from financial markets, the maintenance of peaceful labour relations, and the consequences of a seniority employment system.
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There are four resolvable Steiner triple systems on fifteen elements. Some generalizations of these systems are presented here.
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The present paper deals with the KAM-theory conditions for systems describing the motion of a particle in central field.
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AMS Subj. Classification: MSC2010: 42C10, 43A50, 43A75
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Fish are an important part of Bangladeshi culture and diet. Bangladesh ranks among the top five freshwater fish producers in the world. Fish are abundant in the thousands of rivers, ponds, lakes and seasonal floodplains across the country. They are a major source of protein for people living near these water bodies. In Bangladesh, many households depend on fish farming for their livelihood. By growing fish in homestead ponds, households have a consistent supply of nutritious fish and can sell the surplus for an income. The USAID-funded Cereal Systems Initiative for South Asia in Bangladesh (CSISA-BD) aimed to increase the income of farming households through increased productivity of aquaculture systems. Key activities of the project included developing and disseminating appropriate improved agricultural technology and quality fish seeds to improve livelihoods, food security and nutrition.
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Background: Pigeonpea ( Cajanus cajan L. Millsp.) is a drought tolerant legume of the Fabaceae family and the only cultivated species in the genus Cajanus. It is mainly cultivated in the semi-arid tropics of Asia and Oceania, Africa and America. In Malawi, it is grown as a source of food and income and for soil improvement in intercropping systems. However, varietal contamination due to natural outcrossing causes significant quality reduction and yield losses. In this study, 48 polymorphic SSR markers were used to assess the diversity among all pigeonpea varieties cultivated in Malawi to determine if a genetic fingerprint could be identified to distinguish the popular varieties. Results: A total of 212 alleles were observed with an average of 5.58 alleles per marker and a maximum of 14 alleles produced by CCttc019 (Marker 40). Polymorphic information content (PIC), ranged from 0.03 to 0.89 with an average of 0.30. A neighbor-joining tree produced 4 clusters. The most commonly cultivated varieties, which include released varieties and cultivated land races, were well-spread across all the clusters observed, indicating that they generally represented the genetic diversity available in Malawi, although substantial variation was evident that can still be exploited through further breeding. Conclusion: Screening of the allelic data associated with the five most popular cultivated varieties, revealed 6 markers – CCB1, CCB7, Ccac035, CCttc003, Ccac026 and CCttc019 – which displayed unique allelic profiles for each of the five varieties. This genetic fingerprint can potentially be applied for seed certification to confirm the genetic purity of seeds that are delivered to Malawi farmers.
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We generalize the Liapunov convexity theorem's version for vectorial control systems driven by linear ODEs of first-order p = 1 , in any dimension d ∈ N , by including a pointwise state-constraint. More precisely, given a x ‾ ( ⋅ ) ∈ W p , 1 ( [ a , b ] , R d ) solving the convexified p-th order differential inclusion L p x ‾ ( t ) ∈ co { u 0 ( t ) , u 1 ( t ) , … , u m ( t ) } a.e., consider the general problem consisting in finding bang-bang solutions (i.e. L p x ˆ ( t ) ∈ { u 0 ( t ) , u 1 ( t ) , … , u m ( t ) } a.e.) under the same boundary-data, x ˆ ( k ) ( a ) = x ‾ ( k ) ( a ) & x ˆ ( k ) ( b ) = x ‾ ( k ) ( b ) ( k = 0 , 1 , … , p − 1 ); but restricted, moreover, by a pointwise state constraint of the type 〈 x ˆ ( t ) , ω 〉 ≤ 〈 x ‾ ( t ) , ω 〉 ∀ t ∈ [ a , b ] (e.g. ω = ( 1 , 0 , … , 0 ) yielding x ˆ 1 ( t ) ≤ x ‾ 1 ( t ) ). Previous results in the scalar d = 1 case were the pioneering Amar & Cellina paper (dealing with L p x ( ⋅ ) = x ′ ( ⋅ ) ), followed by Cerf & Mariconda results, who solved the general case of linear differential operators L p of order p ≥ 2 with C 0 ( [ a , b ] ) -coefficients. This paper is dedicated to: focus on the missing case p = 1 , i.e. using L p x ( ⋅ ) = x ′ ( ⋅ ) + A ( ⋅ ) x ( ⋅ ) ; generalize the dimension of x ( ⋅ ) , from the scalar case d = 1 to the vectorial d ∈ N case; weaken the coefficients, from continuous to integrable, so that A ( ⋅ ) now becomes a d × d -integrable matrix; and allow the directional vector ω to become a moving AC function ω ( ⋅ ) . Previous vectorial results had constant ω, no matrix (i.e. A ( ⋅ ) ≡ 0 ) and considered: constant control-vertices (Amar & Mariconda) and, more recently, integrable control-vertices (ourselves).
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