935 resultados para Irregularly spaced returns


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This guide introduces Data Envelopment Analysis (DEA), a performance measurement technique, in such a way as to be appropriate to decision makers with little or no background in economics and operational research. The use of mathematics is kept to a minimum. This guide therefore adopts a strong practical approach in order to allow decision makers to conduct their own efficiency analysis and to easily interpret results. DEA helps decision makers for the following reasons: - By calculating an efficiency score, it indicates if a firm is efficient or has capacity for improvement. - By setting target values for input and output, it calculates how much input must be decreased or output increased in order to become efficient. - By identifying the nature of returns to scale, it indicates if a firm has to decrease or increase its scale (or size) in order to minimize the average cost. - By identifying a set of benchmarks, it specifies which other firms' processes need to be analysed in order to improve its own practices.

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Jatropha curcas is promoted internationally for its presumed agronomic viability in marginal lands, economic returns for small farmers, and lack of competition with food crops. However, empirical results from a study in southern India revealed that Jatropha cultivation, even on agricultural lands, is neither profitable, nor pro-poor. We use a political ecology framework to analyze both the discourse promoting Jatropha cultivation and its empirical consequences. We deconstruct the shaky premises of the dominant discourse of Jatropha as a “pro-poor” and “pro-wasteland” development crop, a discourse that paints a win-win picture between poverty alleviation, natural resource regeneration, and energy security goals. We then draw from field-work on Jatropha plantations in the state of Tamil Nadu to show how Jatropha cultivation favors resource-rich farmers, while possibly reinforcing existing processes of marginalization of small and marginal farmers.

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The relationship between infrastructures and productivity has been the subject of an ongoing debate during the last two decades. The available empirical evidence is inconclusive and its interpretation is complicated by econometric problems that have not been fully solved. This paper surveys the relevant literature, focusing on studies that estimate aggregate production functions or growth regressions, and extracts some tentative conclusions. On the whole, my reading of the evidence is that there are sufficient indications that public infrastructure investment contributes significantly to productivity growth, at least for countries where a saturation point has not been reached. The returns to such investment are probably quite high in early stages, when infrastructures are scarce and basic networks have not been completed, but fall sharply thereafter. Hence, appropriate infrastructure provision is probably a key input for development policy, even if it does not hold the key to rapid productivity growth in advanced countries where transportation and communications needs are already adequately served.

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Viral replication, histopathological and ultrastructural changes were observed for a period of nine days in the small intestine of suckling mice infected with a simian rotavirus (SA11). Samples taken from duodenum, jejunun and ileum were prepared for light microscopy, transmission and scanning electron microscopy analysis. Histopathologic effect could be detected within 8 hr post-infection, when only a few altered cells were observed. Damage was extensive after 16 hr post-infection, showing swollen enterocytes and reduced and irregularly oriented microvilli at intestinal villi tips. Virus particles were detected at 16 and 48 hr post-infection, budding from the viroplasm into the rough endoplasmic reticulum cisternae in ileum enterocytes. Clear evidence of viral replication, observed by electron microscopy was not described before in heterologous murine models. Regeneration of the intestinal villi began at the third day post-infection. Despite some differences observed in clinical symptoms and microscopic analysis of homologous and heterologous rotavirus infections, we concluded that mechanisms of heterologous rotavirus infection in mice follow similar patterns to those observed in the homologous models.

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As fitness returns during a breeding attempt are context-dependent, parents are predicted to bias their food allocation within a brood from poor towards good condition nestlings when environmental conditions deteriorate. We tested this prediction in the Alpine swift and the European starling, two migratory bird species, by modifying an ultraviolet (UV) visual signal of condition in nestlings and exploring how parents allocate food to their young as the season progresses. We show in both species that: (i) UV light reflected by the body skin of offspring positively correlates with their stature (i.e. body mass and skeletal size) and (ii) parental favouritism towards young with more UV reflective skin gradually increases as the season progresses. Early-breeding parents supplied food preferentially to UV pale (i.e. small stature) nestlings, whereas late-breeding parents favoured UV bright offspring (i.e. large stature). These results emphasize that parents use UV signals of offspring condition to adjust their feeding strategies depending on the ecological context.

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Ultrastructural aspects of spermatogenesis, spermiogenesis and of the mature spermatozoon of a microcotylid monogenean Metamicrocotyla macracantha parasite from Mugil liza, are described. The irregularly-shaped spermatogonia divides by successive mitoses, forming the primary spermatocytes, identified by the presence of synaptonemal complexes in their nuclei. The spermatids formed by meiotic cell divisions of the secondary spermatocytes, differentiate into a mature spermatozoon. Cross sections of the head and the middle region of mature spermatozoa show the nucleus with strong condensed chromatin, the mitochondria with short cristae, peripheral microtubules and two axonemes with a 9+1 pattern, confirming the characteristics of this genus.

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In this study we analyze multinationality (domestic-based firms vs. multinationals) and foreignness (foreign vs. domestic firms) effects in the returns of R&D to productivity. We follow a two-step strategy. In the first step, we consistently ''s productivity by GMM and numerically compute the sample distribution of the R&D returns. In the second step, we use stochastic dominance techniques to make inferences on the multinationality and foreignness effects. Results for a panel of UK manufacturing firms suggest that multinationality and foreignness effects operate in an opposite way: whilst the multinationality effect enhances R&D returns, the foreignness diminishes them.

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Abstract: We scrutinize the realized stock-bond correlation based upon high frequency returns. We use quantile regressions to pin down the systematic variation of the extreme tails over their economic determinants. The correlation dependence behaves differently when the correlation is large negative and large positive. The important explanatory variables at the extreme low quantile are the short rate, the yield spread, and the volatility index. At the extreme high quantile the bond market liquidity is also important. The empirical fi…ndings are only partially robust to using less precise measures of the stock-bond correlation. The results are not caused by the recent …financial crisis. Keywords: Extreme returns; Financial crisis; Realized stock-bond correlation; Quantile regressions; VIX. JEL Classifi…cations: C22; G01; G11; G12

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This paper surveys the empirical literature on human capital and productivity and summarizes the results of my own work on the subject. On balance, the available evidence suggests that investment in education has a positive, significant and sizable effect on productivity growth. According to my estimates, moreover, the social returns to investment in human capital are higher than those on physical capital in most EU countries and in many regions of Spain.

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We analyze the transitional dynamics of a model with heterogeneous consumption goods. In this model, convergence is driven by two different forces: the typical diminishing returns to capital and the sectoral change inducing the variation in relative prices. We show that this second force affects the growth rate if the two consumption goods are not Edgeworth independent and if these two goods are produced with technologies exhibiting different capital intensities. Because the afore mentioned dynamic sectoral change arises only under heterogeneous consumption goods, the transitional dynamics of this model exhibits striking differences with the growth model with a single consumption good. We also show that these differences in the transitional dynamics can give raise to large discrepancies in the welfare cost of shocks between the economy with a unique consumption good and the economy with multiple consumption goods.

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The Urban Regeneration and Community Development Policy Framework for Northern Ireland sets out for DSD and its partners, clear priorities for urban regeneration and community development programmes, both before and after the operational responsibility for these is transferred to councils under the reform of local government. Four policy objectives have been developed, which will focus on the underlying structural problems in urban areas and also help strengthen community development throughout Northern Ireland. The policy objectives are as follows: Policy Objective 1 – To tackle area-based deprivation: Policy Objective 2 – To strengthen the competitiveness of our towns and cities: Policy Objective 3 – To improve linkages between areas of need and areas of opportunity: and Policy Objective 4 –To develop more cohesive and engaged communities. Key points from IPH response Urban regeneration and community development provide a basis for addressing the social determinants of health and reducing inequalities in health. This policy framework presents an opportunity for coherence and complementarity with ‘Fit and Well - Changing Lives’ as part of government’s overall approach to tackling health inequalities. It is now well established that a focus on early years’ interventions and family support services yields significant returns, so prioritising action in these areas is essential. Defined action plans on child poverty are essential if this policy framework is to make a real and lasting difference in deprived urban areas. Development of the environmental infrastructure to improve health in deprived areas should be supported by well-planned monitoring and evaluation. Linking the policy framework to economic development and local community plans will enhance effectiveness in the areas of education, job creation, commercial investment and access to services, which in turn are critical for the economic growth and stability of urban communities. Community profile data and health intelligence (as available through IPH Health Well) could usefully inform central and local government in terms of resource allocation and targeted service delivery.

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Eimeria motelo sp. n. is described from faeces of the yellow-footed tortoise, Geochelone denticulata (L.). Oocysts are irregularly ellipsoidal or cylindrical, with slightly expressed lobed protrusions and irregularities at the poles, possibly caused by wrinkling of the oocyst wall, 17 (15-19) × 9.4 (8.5-11) µm, shape index (length/width) being 1.81 (1.45-2). The oocyst wall is smooth, single-layered, 0.5 µm thick with no micropyle. There are no polar bodies. Sporocysts are ellipsoidal, 8.9 (7.5-10) × 4.4 (4-5) µm, shape index 2.03 (1.7-2.5). A sporocyst residuum is present, composed of many granules of irregular size. The sporozoites are elongate, lying lengthwise in the sporocysts. Comparison with other species of the genus Eimeria parasitising members of family Testudinidae indicates that the presently described coccidium represents a new species. The name of Eimeria carinii Lainson, Costa & Shaw, 1990 is found to be preoccupied by a homonym, Eimeria carinii Pinto 1928 given to a coccidium from Rattus norvegicus. Therefore, it is replaced by Eimeria lainsoni nom. nov.

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The aim of this paper is to measure the returns to human capital. We use a unique data set consisting of matched employer-employee information. Data on individuals' human capital include a set of 26 competences that capture the utilization of workers' skills in a very detailed way. Thus, we can expand the concept of human capital and discuss the type of skills that are more productive in the workplace and, hence, generate a higher payoff for the workers. The rich information on firm's and workplace characteristics allows us to introduce a broad range of controls and to improve previous research in this field. This paper gives evidence that the returns to generic competences differ depending on the position of the worker in the firm. Only numeracy skills are reward independent of the occupational status of the worker. The level of technology used by the firm in the production process does not directly increase workers’ pay, but it influences the pay-off to some of the competences. JEL Classification: J24, J31

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Statistical information based on the Children Order returns for NI up to 31st March 2005

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This thesis focuses on theoretical asset pricing models and their empirical applications. I aim to investigate the following noteworthy problems: i) if the relationship between asset prices and investors' propensities to gamble and to fear disaster is time varying, ii) if the conflicting evidence for the firm and market level skewness can be explained by downside risk, Hi) if costly learning drives liquidity risk. Moreover, empirical tests support the above assumptions and provide novel findings in asset pricing, investment decisions, and firms' funding liquidity. The first chapter considers a partial equilibrium model where investors have heterogeneous propensities to gamble and fear disaster. Skewness preference represents the desire to gamble, while kurtosis aversion represents fear of extreme returns. Using US data from 1988 to 2012, my model demonstrates that in bad times, risk aversion is higher, more people fear disaster, and fewer people gamble, in contrast to good times. This leads to a new empirical finding: gambling preference has a greater impact on asset prices during market downturns than during booms. The second chapter consists of two essays. The first essay introduces a foramula based on conditional CAPM for decomposing the market skewness. We find that the major market upward and downward movements can be well preadicted by the asymmetric comovement of betas, which is characterized by an indicator called "Systematic Downside Risk" (SDR). We find that SDR can efafectively forecast future stock market movements and we obtain out-of-sample R-squares (compared with a strategy using historical mean) of more than 2.27% with monthly data. The second essay reconciles a well-known empirical fact: aggregating positively skewed firm returns leads to negatively skewed market return. We reconcile this fact through firms' greater response to negative maraket news than positive market news. We also propose several market return predictors, such as downside idiosyncratic skewness. The third chapter studies the funding liquidity risk based on a general equialibrium model which features two agents: one entrepreneur and one external investor. Only the investor needs to acquire information to estimate the unobservable fundamentals driving the economic outputs. The novelty is that information acquisition is more costly in bad times than in good times, i.e. counter-cyclical information cost, as supported by previous empirical evidence. Later we show that liquidity risks are principally driven by costly learning. Résumé Cette thèse présente des modèles théoriques dévaluation des actifs et leurs applications empiriques. Mon objectif est d'étudier les problèmes suivants: la relation entre l'évaluation des actifs et les tendances des investisseurs à parier et à crainadre le désastre varie selon le temps ; les indications contraires pour l'entreprise et l'asymétrie des niveaux de marché peuvent être expliquées par les risques de perte en cas de baisse; l'apprentissage coûteux augmente le risque de liquidité. En outre, des tests empiriques confirment les suppositions ci-dessus et fournissent de nouvelles découvertes en ce qui concerne l'évaluation des actifs, les décisions relatives aux investissements et la liquidité de financement des entreprises. Le premier chapitre examine un modèle d'équilibre où les investisseurs ont des tendances hétérogènes à parier et à craindre le désastre. La préférence asymétrique représente le désir de parier, alors que le kurtosis d'aversion représente la crainte du désastre. En utilisant les données des Etats-Unis de 1988 à 2012, mon modèle démontre que dans les mauvaises périodes, l'aversion du risque est plus grande, plus de gens craignent le désastre et moins de gens parient, conatrairement aux bonnes périodes. Ceci mène à une nouvelle découverte empirique: la préférence relative au pari a un plus grand impact sur les évaluations des actifs durant les ralentissements de marché que durant les booms économiques. Exploitant uniquement cette relation générera un revenu excédentaire annuel de 7,74% qui n'est pas expliqué par les modèles factoriels populaires. Le second chapitre comprend deux essais. Le premier essai introduit une foramule base sur le CAPM conditionnel pour décomposer l'asymétrie du marché. Nous avons découvert que les mouvements de hausses et de baisses majeures du marché peuvent être prédits par les mouvements communs des bêtas. Un inadicateur appelé Systematic Downside Risk, SDR (risque de ralentissement systématique) est créé pour caractériser cette asymétrie dans les mouvements communs des bêtas. Nous avons découvert que le risque de ralentissement systématique peut prévoir les prochains mouvements des marchés boursiers de manière efficace, et nous obtenons des carrés R hors échantillon (comparés avec une stratégie utilisant des moyens historiques) de plus de 2,272% avec des données mensuelles. Un investisseur qui évalue le marché en utilisant le risque de ralentissement systématique aurait obtenu une forte hausse du ratio de 0,206. Le second essai fait cadrer un fait empirique bien connu dans l'asymétrie des niveaux de march et d'entreprise, le total des revenus des entreprises positiveament asymétriques conduit à un revenu de marché négativement asymétrique. Nous décomposons l'asymétrie des revenus du marché au niveau de l'entreprise et faisons cadrer ce fait par une plus grande réaction des entreprises aux nouvelles négatives du marché qu'aux nouvelles positives du marché. Cette décomposition révélé plusieurs variables de revenus de marché efficaces tels que l'asymétrie caractéristique pondérée par la volatilité ainsi que l'asymétrie caractéristique de ralentissement. Le troisième chapitre fournit une nouvelle base théorique pour les problèmes de liquidité qui varient selon le temps au sein d'un environnement de marché incomplet. Nous proposons un modèle d'équilibre général avec deux agents: un entrepreneur et un investisseur externe. Seul l'investisseur a besoin de connaitre le véritable état de l'entreprise, par conséquent, les informations de paiement coutent de l'argent. La nouveauté est que l'acquisition de l'information coute plus cher durant les mauvaises périodes que durant les bonnes périodes, comme cela a été confirmé par de précédentes expériences. Lorsque la récession comamence, l'apprentissage coûteux fait augmenter les primes de liquidité causant un problème d'évaporation de liquidité, comme cela a été aussi confirmé par de précédentes expériences.