854 resultados para marginal costs
Resumo:
1. Costs of reproduction lie at the core of basic ecological and evolutionary theories, and their existence is commonly invoked to explain adaptive processes. Despite their sheer importance, empirical evidence for the existence and quantification of costs of reproduction in tree species comes mostly from correlational studies, while more comprehensive approaches remain missing. Manipulative experiments are a preferred approach to study cost of reproduction, as they allow controlling for otherwise inherent confounding factors like size or genetic background. 2. Here, we conducted a manipulative experiment in a Pinus halepensis common garden, removing developing cones from a group of trees and comparing growth and reproduction after treatment with a control group. We also estimated phenotypic and genetic correlations between reproductive and vegetative traits. 3. Manipulated trees grew slightly more than control trees just after treatment, with just a transient, marginally non-significant difference. By contrast, larger differences were observed for the number of female cones initiated 1 year after treatment, with an increase of 70% more cones in the manipulated group. Phenotypic and genetic correlations showed that smaller trees invested a higher proportion of their resources in reproduction, compared with larger trees, which could be interpreted as an indirect evidence for costs of reproduction. 4. Synthesis. This research showed a high impact of current reproduction on reproductive potential, even when not significant on vegetative growth. This has strong implications for how we understand adaptive strategies in forest trees and should encourage further interest on their still poorly known reproductive life-history traits.
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In this paper we study network structures in which the possibilities for cooperation are restricted and can not be described by a cooperative game. The benefits of a group of players depend on how these players are internally connected. One way to represent this type of situations is the so-called reward function, which represents the profits obtainable by the total coalition if links can be used to coordinate agents' actions. The starting point of this paper is the work of Vilaseca et al. where they characterized the reward function. We concentrate on those situations where there exist costs for establishing communication links. Given a reward function and a costs function, our aim is to analyze under what conditions it is possible to associate a cooperative game to it. We characterize the reward function in networks structures with costs for establishing links by means of two conditions, component permanence and component additivity. Finally, an economic application is developed to illustrate the main theoretical result.
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Networks are evolving toward a ubiquitous model in which heterogeneousdevices are interconnected. Cryptographic algorithms are required for developing securitysolutions that protect network activity. However, the computational and energy limitationsof network devices jeopardize the actual implementation of such mechanisms. In thispaper, we perform a wide analysis on the expenses of launching symmetric and asymmetriccryptographic algorithms, hash chain functions, elliptic curves cryptography and pairingbased cryptography on personal agendas, and compare them with the costs of basic operatingsystem functions. Results show that although cryptographic power costs are high and suchoperations shall be restricted in time, they are not the main limiting factor of the autonomyof a device.
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This correspondence studies the formulation of members ofthe Cohen-Posch class of positive time-frequency energy distributions.Minimization of cross-entropy measures with respect to different priorsand the case of no prior or maximum entropy were considered. It isconcluded that, in general, the information provided by the classicalmarginal constraints is very limited, and thus, the final distributionheavily depends on the prior distribution. To overcome this limitation,joint time and frequency marginals are derived based on a "directioninvariance" criterion on the time-frequency plane that are directly relatedto the fractional Fourier transform.
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The evolution of reproductive division of labour and social life in social insects has lead to the emergence of several life-history traits and adaptations typical of larger organisms: social insect colonies can reach masses of several kilograms, they start reproducing only when they are several years old, and can live for decades. These features and the monopolization of reproduction by only one or few individuals in a colony should affect molecular evolution by reducing the effective population size. We tested this prediction by analysing genome-wide patterns of coding sequence polymorphism and divergence in eusocial vs. noneusocial insects based on newly generated RNA-seq data. We report very low amounts of genetic polymorphism and an elevated ratio of nonsynonymous to synonymous changes - a marker of the effective population size - in four distinct species of eusocial insects, which were more similar to vertebrates than to solitary insects regarding molecular evolutionary processes. Moreover, the ratio of nonsynonymous to synonymous substitutions was positively correlated with the level of social complexity across ant species. These results are fully consistent with the hypothesis of a reduced effective population size and an increased genetic load in eusocial insects, indicating that the evolution of social life has important consequences at both the genomic and population levels.
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Toiminnanohjausjärjestelmän implementointi ja sen mukanaan tuomat muutokset tuotekustannuslaskentaan asettavat haasteita yritykselle. Metallitoimialalla toimivassa yrityksessä on havaittu samat haasteet implementoitaessa SAP R/3 toiminnanohjausjärjestelmää ja sen tuotekustannuslaskentatoiminnallisuutta. SAP R/3 tuotekustannuslogiikka tarvitsee tietoa järjestelmän ulkopuolelta, minkä huomioimatta jättäminen vaikuttaa suoraan laskentatarkkuuteen. Diplomityössä kehitetään sekä standardoitu prosessi että laskentajärjestelmä, joiden avulla pystytään laskemaan tarvittavat niin toimintokustannukset eri teräspalvelukeskuksen kuormituspisteille kuin kustannustenvyörytysarvot. Lasketut arvot muodostavat tarvittavat tekijät SAP R/3 tuotekustannuslaskennan master dataan. Tavoitteena on edesauttaa läpinäkyvän kustannustiedon muodostumista. Diplomityö pohjautuu ns. vesiputousmalliin (SDLC). Ensin tunnistetaan reunaehdot ympäristöstä, jossa tuotekustannuslaskenta toteutetaan. Tämä asettaa joustamattomia komponentteja kehitettävälle laskentajärjestelmälle. Joustavat komponentit sen sijaan antavat vapautta laskentajärjestelmälle. Yhdistämällä joustamattomat ja joustavat komponentit saavutetaan järjestelmä, jolla voidaan täydentää SAP R/3 tuotekustannuslaskennan puutteellisuutta.
Resumo:
Diplomityössä selvitetään Imatran Seudun Sähkö Oy:n myynti- ja siirtotuotteiden kehitystarpeita. Työssä tarkastellaan käytössä olevien siirtotuotteiden kustannusvastaavuutta, lakkautustuotteiden tulevaisuutta ja tarvetta uusille tuotteille. Lopuksi lasketaan uusi siirtohinnoittelumalli ja sitä tukevat myyntituotteet. Työn alussa perehdytään tariffisuunnittelun periaatteisiinja tehdään kulutusanalyysi Imatran Seudun Sähkö Oy:ssä 1999 tehdyn tehoennusteen ja edellisten vuosien kulutustietojen pohjalta. Seuraavaksi selvitetään sähkönsiirrosta aiheutuvat kustannukset kustannusanalyysissä rajakustannus- ja keskikustannuslaskentaa soveltaen ja kohdistetaan kustannukset käyttäjille. Kun sähkönsiirron aiheuttamat kustannukset on selvitetty, voidaan käytössä olevien ja kehitettävien siirtotuotteiden kustannusvastaavuus ja sopivuus käyttäjille määrittää. Lopuksi tuotteet muotoillaan järkeväksi kokonaisuudeksi muuttamalla energiamaksun ja perus- tai tehomaksun painoja. Tariffien suunnittelussa mitoitetaan tulot niin, että ne kattavat kaikki kulut ja tuottovaatimuksen.
Resumo:
Teorian mukaan täydellisen kilpailun päästöoikeuskauppamarkkinoilla päästöoikeuden hinta muodostuu markkinoilla vallitsevan päästöjen vähentämisen rajakustannuksen perusteella. Euroopan päästökauppamarkkinoilla päästöjen vähentämisen kustannuksia nostavat suhteellisen lyhyet päästökauppajaksot ja epävarmuus järjestelmän jatkuvuudesta. Toisaalta päästökaupan osallistujien yhteenlaskettu päästöjen vähentämisen tarve lienee suhteellisen vähäinen ellei olematon ensimmäisellä päästökauppajaksolla. Euroopan päästökauppamarkkinoilla päästöjen vähentämisen tarve ja päästöjenvähentämisen kustannukset ovat osittain riippuvaisia muuttuvista tekijöistä. Päästöoikeuden hintaan voivat vaikuttaa päästökauppajakson aikana tapahtuva teollisuuden suhdannevaihtelu, polttoaineiden hintojen heilahtelut sekä säätilojen vaihtelu. Päästökaupan ensimmäisinä kuukausina päästöoikeuden hintakehityksellä on ollut yhteyksiä tekijöihin, joiden muutosten tulisikin vaikuttaa päästökauppamarkkinoiden tasapainoon. Näitä tekijöitä ovat esimerkiksi polttoainemarkkinoiden ja sähkömarkkinoiden hintakehitys sekä vaihtelut säätiloissa.
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Finnish food producers' trade with Russia has experienced profound changes since the collapse of the Soviet Union. Simultaneously, the distribution systems of foodstuffs have changed remarkably. This study sheds some light into these changes and analyses the current situation in distribution systems of foodstuffs in Russia. In addition, the study discusses the possibilities of Finnish food producers to get more of their products to the shelves of Russian food retail stores. Before the 1998 financial crisis, the import of foreign foodstuffs was booming in Russia due to the overvalued rouble. As a result of the financial crisis, food import collapsed. The export of Finnish foodstuffs to Russia has been slowly recovering during the past few years, but in the most important product categories the pre-crisis levels have so far not been reached and maybe will not be reached. In certain product categories the growth has been only marginal. It seems that starting localproduction will become increasingly important in the future. This is further encouraged by the fact that Russian consumers favour domestic food products. Russian consumers are very price conscious and demand quality in food products. The perceived price-quality ratio is an important criterion in the purchase decision.The majority of foodstuff retail is still conducted via unorganised forms of trade (e.g. kiosks and marketplaces) but modern retail chains are developing at a fast pace in Russia. They are also expected to dominate the retail trade in foodstuffs over the unorganised forms of trade in the future. This will change the distribution systems as well. The retail chains are trying to shorten the distribution chain, similarly to what has been seen in the Western countries. This together with the strengthening of retail chains is likely to shrink the role of wholesalers, as the chains increasingly want to work directly with the producers. Many large retail chains are acquiring or have already acquired a distribution centre or centres in order to boost efficiency and control the flow of products. The strengthening of the retail chains also gives them power in negotiations, which the producers and distributors have to adjust to. For example store entry fees and retail chains' own private label products pose challenges to the food producers. In the food production sector the competition is fierce, as large Russianand foreign producers want to ensure their piece of the market. The largest producers utilise their size: they invest in big marketing campaigns and are willing to pay high entry fees to retail chains in order to secure a place on the store shelves and to build a strong brand in Russia. This complicates the situation from the viewpoint of small producers. Currently, the most popular type of distribution system among the interviewed Finnish food producers is based on a network of local distributors. There is, however, a strong consensus on the importanceof starting local production in order to be a serious actor in Russia in the future. Factors that hinder the starting of local production include the lack of local infrastructure and qualified staff, and the low risk tolerance of Finnish firms. Major barriers for entry in Russia are the actions of authorities, fierce competition, fragmented market and Finnish producers' heavy production costs. The suggested strategies for increasing the market share include focusing geographically or segment-wise, introducing new products, starting local production, andcooperation between Finnish producers. Smallness was one reason why Finnish producers had to cut down their operations in Russia due to the 1998 crisis. Smaller producers had fewer resources to tolerate losses during the period of crisis. Smallness is reflected also on trade negotiations with retail chains and distributors. It makes it harder to cope with the store entry fees and to differentiatefrom the mass of products propped up by expensive advertising. Finally, it makes it harder for Finnish producers to start or expand local production, as it is more difficult for a small producer to get financing and to tolerate the increased risks. Compensating for the smallness might become the crucial factor determining the future success of Finnish food producers in the Russian market.
Resumo:
Over 70% of the total costs of an end product are consequences of decisions that are made during the design process. A search for optimal cross-sections will often have only a marginal effect on the amount of material used if the geometry of a structure is fixed and if the cross-sectional characteristics of its elements are property designed by conventional methods. In recent years, optimalgeometry has become a central area of research in the automated design of structures. It is generally accepted that no single optimisation algorithm is suitable for all engineering design problems. An appropriate algorithm, therefore, mustbe selected individually for each optimisation situation. Modelling is the mosttime consuming phase in the optimisation of steel and metal structures. In thisresearch, the goal was to develop a method and computer program, which reduces the modelling and optimisation time for structural design. The program needed anoptimisation algorithm that is suitable for various engineering design problems. Because Finite Element modelling is commonly used in the design of steel and metal structures, the interaction between a finite element tool and optimisation tool needed a practical solution. The developed method and computer programs were tested with standard optimisation tests and practical design optimisation cases. Three generations of computer programs are developed. The programs combine anoptimisation problem modelling tool and FE-modelling program using three alternate methdos. The modelling and optimisation was demonstrated in the design of a new boom construction and steel structures of flat and ridge roofs. This thesis demonstrates that the most time consuming modelling time is significantly reduced. Modelling errors are reduced and the results are more reliable. A new selection rule for the evolution algorithm, which eliminates the need for constraint weight factors is tested with optimisation cases of the steel structures that include hundreds of constraints. It is seen that the tested algorithm can be used nearly as a black box without parameter settings and penalty factors of the constraints.
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En el imaginario colectivo de la sociedad de posguerra siempre están presentes las duras condiciones de la vida cotidiana. La población infantil fue especialmente sensible a esta situación debido al alto índice de enfermedades infecciosas, el racionamiento dietético y las angustias derivadas del conflicto bélico. En estas condiciones, el Auxilio Social de la Falange fue el encargado de administrar la beneficencia y, a su vez, resocializar la población, en este caso, la infantil, dentro de los valores nacionalsindicalistas y nacionalcatólicos. Ello le permitió no sólo controlar la política social sino también criminalizar a los vencidos en el momento de administrarla. En definitiva, fue uno de los pilares fundamentales en el proceso de construcción del edificio franquista.
Resumo:
Yeast successfully adapts to an environmental stress by altering physiology and fine-tuning metabolism. This fine-tuning is achieved through regulation of both gene expression and protein activity, and it is shaped by various physiological requirements. Such requirements impose a sustained evolutionary pressure that ultimately selects a specific gene expression profile, generating a suitable adaptive response to each environmental change. Although some of the requirements are stress specific, it is likely that others are common to various situations. We hypothesize that an evolutionary pressure for minimizing biosynthetic costs might have left signatures in the physicochemical properties of proteins whose gene expression is fine-tuned during adaptive responses. To test this hypothesis we analyze existing yeast transcriptomic data for such responses and investigate how several properties of proteins correlate to changes in gene expression. Our results reveal signatures that are consistent with a selective pressure for economy in protein synthesis during adaptive response of yeast to various types of stress. These signatures differentiate two groups of adaptive responses with respect to how cells manage expenditure in protein biosynthesis. In one group, significant trends towards downregulation of large proteins and upregulation of small ones are observed. In the other group we find no such trends. These results are consistent with resource limitation being important in the evolution of the first group of stress responses.
Resumo:
Transmission of drug-resistant pathogens presents an almost-universal challenge for fighting infectious diseases. Transmitted drug resistance mutations (TDRM) can persist in the absence of drugs for considerable time. It is generally believed that differential TDRM-persistence is caused, at least partially, by variations in TDRM-fitness-costs. However, in vivo epidemiological evidence for the impact of fitness costs on TDRM-persistence is rare. Here, we studied the persistence of TDRM in HIV-1 using longitudinally-sampled nucleotide sequences from the Swiss-HIV-Cohort-Study (SHCS). All treatment-naïve individuals with TDRM at baseline were included. Persistence of TDRM was quantified via reversion rates (RR) determined with interval-censored survival models. Fitness costs of TDRM were estimated in the genetic background in which they occurred using a previously published and validated machine-learning algorithm (based on in vitro replicative capacities) and were included in the survival models as explanatory variables. In 857 sequential samples from 168 treatment-naïve patients, 17 TDRM were analyzed. RR varied substantially and ranged from 174.0/100-person-years;CI=[51.4, 588.8] (for 184V) to 2.7/100-person-years;[0.7, 10.9] (for 215D). RR increased significantly with fitness cost (increase by 1.6[1.3,2.0] per standard deviation of fitness costs). When subdividing fitness costs into the average fitness cost of a given mutation and the deviation from the average fitness cost of a mutation in a given genetic background, we found that both components were significantly associated with reversion-rates. Our results show that the substantial variations of TDRM persistence in the absence of drugs are associated with fitness-cost differences both among mutations and among different genetic backgrounds for the same mutation.
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The aim of this study was to estimate the production cost and economic indicators associated with the production and sales of fruits from 20 custard apple progenies during the initial five harvests, in order to identify the harvest season from which custard apple exploitation becomes profitable, as well as the most promising progenies from an economic point of view. The fruit yield data upon which the present work was based were obtained during the period from 2001 to 2005, in an experiment that evaluated 20 custard apple half-sibling progenies, under sprinkler irrigation. The progenies were evaluated in a random block design with five replicates and plots consisting of four plants each. The exploitation of custard apple progenies only showed to be a profitable agribusiness after the fourth year. Before that, only A3 and A4 progenies in the second year, and P3 and P11 in the third year provided profitable incomes. Considering the methodological assumptions imposed concerning the time period analysis and the prices as of July 2007, the most important profitability indicators (operating profit, return index and equilibrium price) evidenced that the A4 progeny is the most recommended, although other progenies are also highlighted, such as FJ1 and FJ2. As already discussed, the progenies showing the highest average yields of five harvests are not always the most economically recommendable ones.
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To characterise the genetics of splenic marginal zone lymphoma (SMZL), we performed whole exome sequencing of 16 cases and identified novel recurrent inactivating mutations in Kruppel-like factor 2 (KLF2), a gene whose deficiency was previously shown to cause splenic marginal zone hyperplasia in mice. KLF2 mutation was found in 40 (42%) of 96 SMZLs, but rarely in other B-cell lymphomas. The majority of KLF2 mutations were frameshift indels or nonsense changes, with missense mutations clustered in the C-terminal zinc finger domains. Functional assays showed that these mutations inactivated the ability of KLF2 to suppress NF-κB activation by TLR, BCR, BAFFR and TNFR signalling. Further extensive investigations revealed common and distinct genetic changes between SMZL with and without KLF2 mutation. IGHV1-2 rearrangement and 7q deletion were primarily seen in SMZL with KLF2 mutation, while MYD88 and TP53 mutations were nearly exclusively found in those without KLF2 mutation. NOTCH2, TRAF3, TNFAIP3 and CARD11 mutations were observed in SMZL both with and without KLF2 mutation. Taken together, KLF2 mutation is the most common genetic change in SMZL and identifies a subset with a distinct genotype characterised by multi-genetic changes. These different genetic changes may deregulate various signalling pathways and generate cooperative oncogenic properties, thereby contributing to lymphomagenesis.