815 resultados para [JEL:D46] Microeconomics - Market Structure and Pricing - Value Theory
Resumo:
The paper reports a study of children's attitudes to school based on a questionnaire survey of 845 pupils in their first year of secondary school in England, together with interviews with a sample of the children. A clearly structured set of attitudes emerged from a factor analysis which showed a distinction between instrumental and affective aspects of attitudes but also dimensions within these, including a sense of teacher commitment and school as a difficult environment. Virtually all children had a strong sense of the importance of doing well at school. However, a substantial minority were not sure that they would stay on after 16. There were few differences between boys and girls or between children from different socio-economic backgrounds but children planning to leave at 16 enjoyed school less and were less sure that it had anything to offer them. There was an almost universal commitment to the value of education but, for a minority, an ambivalence about the experience and relevance of schooling for them.
Resumo:
This review summarizes the recent discovery of the cupin superfamily (from the Latin term "cupa," a small barrel) of functionally diverse proteins that initially were limited to several higher plant proteins such as seed storage proteins, germin (an oxalate oxidase), germin-like proteins, and auxin-binding protein. Knowledge of the three-dimensional structure of two vicilins, seed proteins with a characteristic beta-barrel core, led to the identification of a small number of conserved residues and thence to the discovery of several microbial proteins which share these key amino acids. In particular, there is a highly conserved pattern of two histidine-containing motifs with a varied intermotif spacing. This cupin signature is found as a central component of many microbial proteins including certain types of phosphomannose isomerase, polyketide synthase, epimerase, and dioxygenase. In addition, the signature has been identified within the N-terminal effector domain in a subgroup of bacterial AraC transcription factors. As well as these single-domain cupins, this survey has identified other classes of two-domain bicupins including bacterial gentisate 1, 2-dioxygenases and 1-hydroxy-2-naphthoate dioxygenases, fungal oxalate decarboxylases, and legume sucrose-binding proteins. Cupin evolution is discussed from the perspective of the structure-function relationships, using data from the genomes of several prokaryotes, especially Bacillus subtilis. Many of these functions involve aspects of sugar metabolism and cell wall synthesis and are concerned with responses to abiotic stress such as heat, desiccation, or starvation. Particular emphasis is also given to the oxalate-degrading enzymes from microbes, their biological significance, and their value in a range of medical and other applications.
Resumo:
Two cobalt complexes, [Co(L-Se)(phen)]center dot CH2Cl2 (1) and [Co(L-Se)(N,N-Me(2)en)(CH3COO-)] (2) have been synthesized and characterized by elemental analyses, magnetic measurements, i.r. studies etc. Single crystal X- ray studies reveal that in complex (1) cobalt atom is in +2 oxidation state with trigonal bipyramidal geometry, while in complex (2) it is in +3 oxidation state and surrounded octahedrally. The asymmetric unit of complex (2) contains two crystallographically independent discrete molecules. Complex (1) was found to be paramagnetic with mu(eff) = 2.19 BM indicating a low spin cobalt(II) d(7) system, whereas complex (2) is found to be diamagnetic with cobalt(III) in low spin d(6) state. The kinetic studies on the reduction of (2) by ascorbic acid in 80% MeCN-20% H2O (v/v) at 25 degrees C reveal that the reaction proceeds through the rapid formation of inner-sphere adduct, probably by replacing the loosely coordinated AcO- group, followed by electron transfer in a slow step and is supported by a large Q (formation constant) value.
Resumo:
Changes in texture, microstructure, colour and protein solubility of Thai indigenous and broiler chicken Pectoralis muscle stripes cooked at different temperatures were evaluated. The change in shear value of both chicken muscles was a significant increase from 50 to 80 degrees C but no change from 80 to 100 degrees C. A significant decrease in fibre diameter was obtained in samples heated to an internal temperature of 60 degrees C and the greatest shrinkage of sarcomeres was observed with internal temperatures of 70-100 and 80-100 C for broiler and indigenous chicken muscles, respectively (P < 0.05). Cooking losses of indigenous chicken muscles increased markedly in the temperature range 80-100 C and were significantly higher than those of the broiler (P < 0.001). With increasing temperature, from 50 to 70 degrees C, cooked chicken muscle became lighter and yellower. Relationships between changes in sarcomere length, fibre diameter, shear value, cooking loss and solubility of muscle proteins were evaluated. It was found that the solubility of muscle protein was very highly correlated with the texture of cooked broiler muscle while sarcomere length changes and collagen solubility were important factors influencing the cooking loss and texture of cooked indigenous chicken muscle. (c) 2004 Elsevier Ltd. All rights reserved.
Resumo:
Insect pollination is important for food production globally and apples are one of the major fruit crops which are reliant on this ecosystem service. It is fundamentally important that the full range of benefits of insect pollination to crop production are understood, if the costs of interventions aiming to enhance pollination are to be compared against the costs of the interventions themselves. Most previous studies have simply assessed the benefits of pollination to crop yield and ignored quality benefits and how these translate through to economic values. In the present study we examine the influence of insect pollination services on farmgate output of two important UK apple varieties; Gala and Cox. Using field experiments, we quantify the influence of insect pollination on yield and importantly quality and whether either may be limited by sub-optimal insect pollination. Using an expanded bioeconomic model we value insect pollination to UK apple production and establish the potential for improvement through pollination service management. We show that insects are essential in the production of both varieties of apple in the UK and contribute a total of £36.7 million per annum, over £6 million more than the value calculated using more conventional dependence ratio methods. Insect pollination not only affects the quantity of production but can also have marked impacts on the quality of apples, influencing size, shape and effecting their classification for market. These effects are variety specific however. Due to the influence of pollination on both yield and quality in Gala, there is potential for insect pollination services to improve UK output by up to £5.7 million per annum. Our research shows that continued pollinator decline could have serious financial implications for the apple industry but there is considerable scope through management of wild pollinators or using managed pollinator augmentation, to improve the quality of production. Furthermore, we show that it is critically important to consider all production parameters including quality, varietal differences and management costs when valuing the pollination service of any crop so investment in pollinator management can be proportional to its contribution.
Resumo:
We study by Langevin molecular dynamics simulations systematically the influence of polydispersity in the particle size, and subsequently in the dipole moment, on the physical properties of ferrofluids. The polydispersity is in a first approximation modeled by a bidisperse system that consists of small and large particles at different ratios of their volume fractions. In the first part of our investigations the total volume fraction of the system is fixed, and the volume fraction phi(L) of the large particles is varied. The initial susceptibility chi and magnetization curve of the systems show a strong dependence on the value of phi(L). With the increase of phi(L), the magnetization M of the system has a much faster increment at weak fields, and thus leads to a larger chi. We performed a cluster analysis that indicates that this is due to the aggregation of the large particles in the systems. The average size of these clusters increases with increasing phi(L). In the second part of our investigations, we fixed the volume fraction of the large particles, and increased the volume fraction phi(S) of the small particles in order to study their influence on the chain formation of the large ones. We found that the average aggregate size formed by large particles decreases when phi(S) is increased, demonstrating a significant effect of the small particles on the structural properties of the system. A topological analysis of the structure reveals that the majority of the small particles remain nonaggregated. Only a small number of them are attracted to the ends of the chains formed by large particles.
Resumo:
The aim of this study was to describe the population structure, inbreeding and to quantify their effect for different weights, of Santa Ines sheep. For this reason, 6490 data of production and 17,097 animals in the pedigree data set were utilized to evaluate birth weight (BW), weight at 60 days (W60) and weight at 180 days (W180). The genetic structure analysis of the population was realized by the software ENDOG (v.4.6.), resulting in some level of inbreeding for 21.72% of the animals in the pedigree data, being 41.02% the maximum value, and average of 10.74% for the inbred individuals. The population average inbreeding was 2.33% and the average relatedness was 0.73%. The effective number of ancestors was 156 animals and the effective number of founders was 211 individuals. A significant depressive effect of the inbreeding can be verified for all traits. The monitored parameters related with the genetic variability on this population must be constant in order to prevent the decrease in the genetic progress. The utilization of a program for directed mating in the present flock is an appropriate alternative to keep the level of inbreeding under control. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
In many mammals social organization promotes genetic structuring, which can be influenced by the dispersal pattern of the species. We analyzed the population genetic structure and dispersal of white-lipped peccaries (Tayassu pecan) from the Pantanal, Brazil. We genotyped 100 individuals at 7 microsatellite loci from 2 adjacent locations with no obvious geographic barrier between them. We found a significant but low F(ST) value, and the Bayesian analysis indicated a unique cluster. No significant differences were observed between mean assignment indices of resident males and females from both locations, and the probability of being born at the location sampled of > 30% of the individuals analyzed was lower than average. Mean relatedness between resident female, male, and opposite-sex pairs was not statistically different in both locations. These results suggest a low degree of genetic differentiation between the locations analyzed, and dispersal by both sexes (contrary to the predicted male-biased dispersal of most mammalian species).
Resumo:
Cell shape, signaling, and integrity depend on cytoskeletal organization. In this study we describe the cytoskeleton as a simple network of filamentary proteins (links) anchored by complex protein structures (nodes). The structure of this network is regulated by a distance-dependent probability of link formation as P = p/d(s), where p regulates the network density and s controls how fast the probability for link formation decays with node distance (d). It was previously shown that the regulation of the link lengths is crucial for the mechanical behavior of the cells. Here we examined the ability of the two-dimensional network to percolate (i.e. to have end-to-end connectivity), and found that the percolation threshold depends strongly on s. The system undergoes a transition around s = 2. The percolation threshold of networks with s < 2 decreases with increasing system size L, while the percolation threshold for networks with s > 2 converges to a finite value. We speculate that s < 2 may represent a condition in which cells can accommodate deformation while still preserving their mechanical integrity. Additionally, we measured the length distribution of F-actin filaments from publicly available images of a variety of cell types. In agreement with model predictions, cells originating from more deformable tissues show longer F-actin cytoskeletal filaments. (C) 2008 Elsevier B.V. All rights reserved.
Resumo:
Two new complexes of platinum(II) and silver(I) with acesulfame were synthesized. Acesulfame is in the anionic form acesulfamate (ace). The structures of both complexes were determined by X-ray crystallography. For K(2)[PtCl(2)(ace)(2)] the platinum atom is coordinated to two Cl(-) and two N-acesulfamate atoms forming a trans-square planar geometry. Each K(+) ion interacts with two oxygen atoms of the S(=O)(2) group of each acesulfamate. For the polymeric complex [Ag(ace)](n) the water molecule bridges between two crystallographic equivalent Agl atoms which are related each other by a twofold symmetry axis. Two Agl atoms, related to each other by a symmetry centre, make bond contact with two equivalent oxygen atoms. These bonds give rise to infinite chains along the unit cell diagonal in the ac plane. The in vitro cytotoxic analyses for the platinum complex using HeLa (human cervix cancer) cells show its low activity when compared to the vehicle-treated cells. The Ag(I) complex submitted to in vitro antimycobacterial tests, using the Microplate Alamar Blue (MABA) method, showed a good activity against Mycobacterium tuberculosis, responsible for tuberculosis, with a minimal inhibitory concentration (MIC) value of 11.6 mu M. The Ag(I) complex also presented a promising activity against Gram negative (Escherichia colt and Pseudomonas aeruginosa) and Gram positive (Enterococcus faecalis) microorganisms. The complex K(2)[PtCl(2)(ace)(2)] was also evaluated for antiviral properties against dengue virus type 2 (New Guinea C strain) in Vero cells and showed a good inhibition of dengue virus type 2 (New Guinea G strain) replication at 200 mu M, when compared to vehicle-treated cells. (C) 2010 Elsevier Inc. All rights reserved.
Resumo:
Expediting new program development can help universities meet student and employer demand while gaining an edge over competitors, but coordinating program development and approval requires careful preparation and execution. This report profiles strategies to measure market demand for new programs, choose programs for accelerated development, and leverage internal resources. The report also suggests ways to structure and staff program development to maximize speed and effectiveness.
Resumo:
The systemic financial crisis that started in 2008 in the United States had some severe effects in the economic activity and required the bailout of financial institutions with the use of taxpayer’s money. It also originated claims for stronger regulatory framework in order to avoid another threat in the financial market. The Dodd Frank Act was proposed and approved in the United States in the aftermath of the crisis and brought, among many other features, the creation of the Financial Stability Oversight Council and the tougher inspection of financial institutions with asset above 50 billion dollars. The objective of this work is to study the causal effect of the Dodd Frank Act on the behavior of the treatment group subject to monitoring by the Financial Stability Oversight Council (financial institutions with assets above 50 billion dollars) regarding capital and compensation structure in comparison to the group that was not treated. We use data from Compustat and our empirical strategy is the Regression Discontinuity Design, not usually applied to the banking literature, but very useful for the present work since it allows us to compare the treatment group and the non-treatment group in the year of the enactment of the law (2010). No change of behavior was observed for the Capital Structure. In the Compensation Schemes, however, a decrease was found in the item other compensation for CEOs and CFOs. We also performed a robustness check by running a placebo test on the variables in the year before the law was enacted. No significance was found, which supports the conclusion that our main results were caused by the enactment of the DFA.
Resumo:
Market risk exposure plays a key role for nancial institutions risk management. A possible measure for this exposure is to evaluate losses likely to incurwhen the price of the portfolio's assets declines using Value-at-Risk (VaR) estimates, one of the most prominent measure of nancial downside market risk. This paper suggests an evolving possibilistic fuzzy modeling approach for VaR estimation. The approach is based on an extension of the possibilistic fuzzy c-means clustering and functional fuzzy rule-based modeling, which employs memberships and typicalities to update clusters and creates new clusters based on a statistical control distance-based criteria. ePFM also uses an utility measure to evaluate the quality of the current cluster structure. Computational experiments consider data of the main global equity market indexes of United States, London, Germany, Spain and Brazil from January 2000 to December 2012 for VaR estimation using ePFM, traditional VaR benchmarks such as Historical Simulation, GARCH, EWMA, and Extreme Value Theory and state of the art evolving approaches. The results show that ePFM is a potential candidate for VaR modeling, with better performance than alternative approaches.
Resumo:
This doctoral thesis is about global brands under several perspectives, starting this study with and overview on the matter, followed by a "step ahead" in the conceptualization of brand equity and brand value. As the global marketplace dynamically increases, there are theoretical and empirical challenges concerning the global brands that ask for more branding researches, trying to tune and to contextualize meanings and attributes. Thereafter, the thesis intends to provide a discussion about the industry and country-of-origin effects (and their interactions) on the brand value and the firm market value. Finally, the thesis offers an interesting comparison about the practitioners’ perspectives on the dimensions of global brands, the brand equity and the brand value, branding and marketing, including highlights on the brand internationalization process. The thesis offers a general approach on the extant literature in the first chapter, and a specific literature review for each other chapter.