893 resultados para Rational expectations


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The Chair of Food Banks UPM arises from a cooperation agreement between the Spanish Federation of Food Banks (FESBAL) and the Technical University of Madrid (UPM), with the aim of raising awareness and promoting rational food consumption to avoid food waste, through activities of training, transfer of knowledge and promotion of I+D+i. The aim of this paper is to reflect on the activities carried out during the first year in order to obtain learning lessons and improve the management of activities and resources.

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When applying computational mathematics in practical applications, even though one may be dealing with a problem that can be solved algorithmically, and even though one has good algorithms to approach the solution, it can happen, and often it is the case, that the problem has to be reformulated and analyzed from a different computational point of view. This is the case of the development of approximate algorithms. This paper frames in the research area of approximate algebraic geometry and commutative algebra and, more precisely, on the problem of the approximate parametrization.

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This paper is framed within the problem of analyzing the rationality of the components of two classical geometric constructions, namely the offset and the conchoid to an algebraic plane curve and, in the affirmative case, the actual computation of parametrizations. We recall some of the basic definitions and main properties on offsets (see [13]), and conchoids (see [15]) as well as the algorithms for parametrizing their rational components (see [1] and [16], respectively). Moreover, we implement the basic ideas creating two packages in the computer algebra system Maple to analyze the rationality of conchoids and offset curves, as well as the corresponding help pages. In addition, we present a brief atlas where the offset and conchoids of several algebraic plane curves are obtained, their rationality analyzed, and parametrizations are provided using the created packages.

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Protein–protein interacting surfaces are usually large and intricate, making the rational design of small mimetics of these interfaces a daunting problem. On the basis of a structural similarity between the CDR2-like loop of CD4 and the β-hairpin region of a short scorpion toxin, scyllatoxin, we transferred the side chains of nine residues of CD4, central in the binding to HIV-1 envelope glycoprotein (gp120), to a structurally homologous region of the scorpion toxin scaffold. In competition experiments, the resulting 27-amino acid miniprotein inhibited binding of CD4 to gp120 with a 40 μM IC50. Structural analysis by NMR showed that both the backbone of the chimeric β-hairpin and the introduced side chains adopted conformations similar to those of the parent CD4. Systematic single mutations suggested that most CD4 residues from the CDR2-like loop were reproduced in the miniprotein, including the critical Phe-43. The structural and functional analysis performed suggested five additional mutations that, once incorporated in the miniprotein, increased its affinity for gp120 by 100-fold to an IC50 of 0.1–1.0 μM, depending on viral strains. The resulting mini-CD4 inhibited infection of CD4+ cells by different virus isolates. Thus, core regions of large protein–protein interfaces can be reproduced in miniprotein scaffolds, offering possibilities for the development of inhibitors of protein–protein interactions that may represent useful tools in biology and in drug discovery.

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A family of nanoscale-sized supramolecular cage compounds with a polyhedral framework is prepared by self-assembly from tritopic building blocks and rectangular corner units via noncovalent coordination interactions. These highly symmetrical cage compounds are described as face-directed, self-assembled truncated tetrahedra with Td symmetry.

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Two-component signaling systems involving receptor-histidine kinases are ubiquitous in bacteria and have been found in yeast and plants. These systems provide the major means by which bacteria communicate with each other and the outside world. Remarkably, very little is known concerning the extracellular ligands that presumably bind to receptor-histidine kinases to initiate signaling. The two-component agr signaling circuit in Staphylococcus aureus is one system where the ligands are known in chemical detail, thus opening the door for detailed structure–activity relationship studies. These ligands are short (8- to 9-aa) peptides containing a thiolactone structure, in which the α-carboxyl group of the C-terminal amino acid is linked to the sulfhydryl group of a cysteine, which is always the fifth amino acid from the C terminus of the peptide. One unique aspect of the agr system is that peptides that activate virulence expression in one group of S. aureus strains also inhibit virulence expression in other groups of S. aureus strains. Herein, it is demonstrated by switching the receptor-histidine kinase, AgrC, between strains of different agr specificity types, that intragroup activation and intergroup inhibition are both mediated by the same group-specific receptors. These results have facilitated the development of a global inhibitor of virulence in S. aureus, which consists of a truncated version of one of the naturally occurring thiolactone peptides.

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Cascade regulatory circuits have been described that control numerous cell processes, and may provide models for the design of artificial circuits with novel properties. Here we describe the design of a transcriptional regulatory cascade to amplify the cell response to a given signal. We used the salicylate-responsive activators of Pseudomonas putida NahR of the naphthalene degradation plasmid NAH7 and XylS2, a mutant regulator of the TOL plasmid for catabolism of m-xylene and their respective cognate promoters Psal and Pm. Control of the expression of xylS2 with the nahR/Psal system permitted either their selective activation with specific effectors for each protein or the simultaneous activation of both of them with salicylate. When cells face the common effector of the two regulators, both the increase in XylS2 concentration and the stimulation of its activity act synergistically on the Pm promoter, amplifying the gene expression capacity by at least one order of magnitude with respect to the individual systems. By changing the hierarchy of regulators, we showed that the specific features of the downstream regulator were crucial for the amplification effect. Directed changes in the effector profile of the regulators allowed the extension of the amplifying system to other molecular signals.

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When administered in high doses to HIV positive (HIV+) individuals, interleukin 2 (IL-2) causes extreme toxicity and markedly increases plasma HIV levels. Integration of the information from the structure-activity relationships of the IL-2 receptor interaction, the cellular distribution of the different classes of IL-2 receptors, and the pharmacokinetics of IL-2 provides for the rationale that low IL-2 doses should circumvent toxicity. Therefore, to identify a nontoxic, but effective and safe IL-2 treatment regimen that does not stimulate viral replication, doses of IL-2 from 62,500 to 250,000 IU/m2/day were administered subcutaneously for 6 months to 16 HIV+ individuals with 200-500 CD4+ T cells/mm3. IL-2 was already detectable in the plasma of most HIV+ individuals even before therapy. Peak plasma IL-2 levels were near saturating for high affinity IL-2 receptors in 10 individuals who received the maximum nontoxic dose, which ranged from 187,500 to 250,000 IU/m2/day. During the 6 months of treatment at this dose range, plasma levels of proinflammatory cytokines remained undetectable, and plasma HIV RNA levels did not change significantly. However, delayed type hypersensitivity responses to common recall antigens were markedly augmented, and there were IL-2 dose-dependent increases in circulating Natural Killer cells, eosinophils, monocytes, and CD4+ T cells. Expanded clinical trials of low dose IL-2 are now warranted, especially in combination with effective antivirals to test for the prevention of immunodeficiency and the emergence of drug-resistant mutants and for the eradication of residual virions.

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O presente trabalho questiona o papel da legislação na realização judicial do direito. Para responder a essa questão, empreende-se uma tese conceitual sobre a dinâmica jurídica, que pretende superar a tradicional dicotomia entre a legislação e a função judicial concebida pela doutrina clássica da separação dos poderes. De acordo com a argumentação desenvolvida aqui, o judiciário julga não somente fatos dos casos, mas também as próprias escolhas legislativas, de modo que já não é possível defender que a função judicial consiste em mera declaração da lei nos casos particulares ou ainda em subsunção lógica das lides que lhe são submetidas às normas previamente postas pelo processo legislativo. Assim, a realização judicial do direito não pode ser anteriormente determinada, uma vez que não está condicionada pelo conteúdo legislado. Contudo, os conteúdos da lei transmitem algum sentido para os cidadãos e, por isso, criam expectativas. Confirmar ou não essas expectativas é uma questão relacionada com a justificação e a legitimidade dos Estados racionais modernos, que estabelecem com os cidadãos uma relação de dominação legal-racional. Desse modo, a questão do papel da legislação (direito positivo passado) na realização do direito atual é posta em termos de legitimidade. Se, de um lado, constatamos que não é possível pretender controlar a discricionariedade judicial dentro dos próprios limites do direito, de outro lado defendemos que é legítimo pretender submeter o direito positivo à crítica e ao controle democrático. Isso porque interessa a todos os cidadãos que as decisões judiciais possam ser justificadas de modo razoável, graças a uma argumentação cuja força e a pertinência se reconheçam amplamente na sociedade. A partir dessa perspectiva, propomos um redimensionamento do argumento legal na prática jurídica e passamos a analisar as diversas implicações da questão central posta neste trabalho na realização judicial do direito.

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We examine the predictive ability and consistency properties of exchange rate expectations for the dollar/euro using a survey conducted in Spain by PwC among a panel of experts and entrepreneurs. Our results suggest that the PwC panel have some forecasting ability for time horizons from 3 to 9 months, although only for the 3-month ahead expectations we obtain marginal evidence of unbiasedness and efficiency in the forecasts. As for the consistency properties of the exchange rate expectations formation process, we find that survey participants form stabilising expectations in the short-run and destabilising expectations in the long- run and that the expectation formation process is closer to fundamentalists than chartists.

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This dissertation engages the question of why German political elites accepted the use of force during the 1990s and started to commit the country's armed forces to multilateral peacekeeping missions. Previous governments of the Federal Republic had opposed foreign deployment of the military and Germany was characterized by a unique strategic culture in which the efficacy of military force was widely regarded as negative. The rediscovery of the use of force constituted a significant reorientation of German security policy with potentially profound implications for international relations. I use social role theory to explain Germany's security policy reorientation. I argue that political elites shared a national role conception of their country as a dependable and reliable ally. Role expectations of the international security environment changed as a result of a general shift to multilateral intervention as means to address emerging security problems after the Cold War. Germany's resistance to the use of force was viewed as inappropriate conduct for a power possessing the economic and military wherewithal of the Federal Republic. Elites from allied countries exerted social pressure to have Germany contribute commensurate with capabilities. German political elites adapted role behavior in response to external expectations in an effort to preserve the national role conception of a dependable and reliable ally. Security policy reorientation to maintain Germany's national role conception was pursued by conservative elites who acted as 'role entrepreneurs'. CDU/CSU politicians initiated a process of role adaptation to include the use of force for non-defensive missions. They persuaded Social Democrats and Alliance 90/Green party politicians that the maintenance of the country's role conception necessitated a reorientation in security policy to accommodate the changes in the security environment.

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While the numbers are slowly rising, Hispanic students continue to be disproportionately underrepresented in all levels of higher education, including doctoral education. There are many factors that may contribute to the low numbers of Hispanic doctoral students; for Hispanic women, one of these factors may be the perceived conflict between cultural expectations of childrearing and doctoral education. For Hispanic students who hold strong cultural values, this conflict may prevent enrollment in, or result in attrition from, doctoral education. As the number of Hispanic college enrollment increases, we will see more students trying to navigate between the collectivistic value of childrearing and the individualistic value of pursuing higher education. Thus, it is important to understand the needs of these students to aid in recruitment and retention of student-parents in all levels of higher education. This paper explores the barriers and supportive factors for current Hispanic doctoral student-parents. Suggestions are made to increase support which will allow these individuals to successfully complete a doctoral education, while attending to the responsibilities of parenting.