Parameterized expectations approach; Some practical issues

We discuss some practical issues related to the use of the Parameterized Expectations Approach (PEA) for solving non-linear stochastic dynamic models with rational expectations. This approach has been applied in models of macroeconomics, financial economics, economic growth, contracttheory, etc. It turns out to be a convenient algorithm, especially when there is a large number of state variables and stochastic shocks in the conditional expectations. We discuss some practical issues having to do with the application of the algorithm, and we discuss a Fortran program for implementing the algorithm that is available through the internet.We discuss these issues in a battery of six examples.

Plano Ambiental Inter-Sectorial Ambiente e Gestão Sustentável da Biodiversidade

Em Cabo Verde, desde a independência, os sucessivos Governos têm-se mostrado preocupados com a questão da preservação dos ecossistemas e com o enquadramento dos organismos vocacionados para a gestão ambiental. Essas preocupações estão expressas nos diversos instrumentos como: -A Constituição da República; -As Grandes Opções do Plano para o período 2001-2006; -O Programa do Governo da VI Legislatura; -As Acções de desenvolvimento. A Constituição da República consagra “o direito do cidadão a um ambiente de vida sadio, ecologicamente equilibrado, devendo defendê-lo e conservá-lo.” Ainda de acordo com a Constituição: “Ao Estado e aos Municípios, com a colaboração das Associações de defesa do Ambiente compete adoptar políticas de defesa e de preservação do ambiente e velar pela utilização racional de todos os recursos naturais.” Na estratégia expressa nas Grandes Opções para o Plano Nacional do Desenvolvimento (2002), o ambiente é um dos temas mais importantes da política. Projecta-se uma sociedade dotada de um sentimento profundo para o ambiente e de uma consciência ecológica desenvolvida sendo as medidas de preservação encaradas de forma sistémica e transversal, pretendendo-se que sejam equitativas. A política ambiental aparece expresso no programa do actual Governo da seguinte forma: “A conservação e o desenvolvimento dos ecossistemas das ilhas de Cabo Verde e a valorização dos seus recursos naturais constituirão uma preocupação central do Governo que deverá ser traduzida numa orientação política de carácter horizontal, em concertação com as outras políticas sectoriais. O Programa do Governo da VI Legislatura, assume a conservação e o desenvolvimento dos ecossistemas das ilhas de Cabo Verde e a valorização dos seus recursos naturais, como uma preocupação central do Governo. Assim, propõe uma orientação política de carácter horizontal, em concertação com as outras políticas sectoriais. Nesta via, a política de desenvolvimento e gestão dos diversos sectores da economia do país, aponta para a valorização dos recursos naturais e a conservação dos ecossistemas, tendo como objectivo, um desenvolvimento durável. Dentro desta linha de orientação e com o objectivo de obter um plano de políticas do ambiente, e definir as orientações estratégicas de aproveitamento dos recursos naturais, e, ainda, os seus efeitos sobre a gestão sustentável das actividades económicas, por forma a que o desenvolvimento económico e social seja sustentável, o Governo de Cabo Verde, com o apoio financeiro e técnico do Governo da Holanda, criou o PANA II para um horizonte temporal de dez anos (2004-2014). O sucesso do PANA II exige o estabelecimento de cenários, etapas, programas, metas e objectivos com índices de verificação concretas, socialmente assumidos por todos os intervenientes no domínio do ambiente: os poderes públicos, o sector privado, as ONGs, e as sociedades civil. Assim, a criação de um sistema de monitorização, que atribui as responsabilidades, delimita etapas, estabelece as normas de conduta, e que padroniza os níveis de qualidade para cada área específica, constitui uma peça imprescindível para uma valorização do nível de vida no país, no horizonte do fim do PANA II. Portanto, a operacionalização do desenvolvimento sustentável exige a elaboração de uma estratégia e a sua monitorização, através de um sistema coerente de indicadores, nomeadamente, ambientais, sociais, institucionais e económicos.

Biologia de Neotrioza tavaresi Crawford, 1925 (Hemiptera, Psyllidae), galhador da folha do araçazeiro (Psidium cattleianum)

Biology of the leaf gall inducer Neotrioza tavaresi Crawford, 1925 (Hemiptera, Psyllidae) on strawberry guava tree (Psidium cattleianum). A field study was conducted in Curitiba region, State of Paraná, southern Brazil, to describe the life cycle of Neotrioza tavaresi Crawford, 1925, a leaf galling insect in strawberry guava trees (Psidium cattleianum). Three cycles were observed (1997, 1998, 1999) during regular field trips and the insects were observed in Piraquara municipality, where 15 samples with 50 infested leaves were sampled in the 1997-98 cycle. Galls were dissected for detailed studies. Neotrioza tavaresi has a univoltine cycle in which adult individuals were found inside the galls from August onwards. The sexually mature insects with sex ratio 1, emerged from the galls after their dehiscence caused by feeding of the adult insects on the gall walls. Adult emergence started in early October and ended by early December, with its peak in November. Copulation took place as soon as adults exit the gall and egg laying started the next day. Females had more than 100 ovarioles containing 218.7±44.7 (n=50) fully formed eggs. This indicated the short sexual adult life-span (aprox. 5-7 days) of the species, also characterized by a concentrated oviposition. Adult individuals fed and laid their eggs on younger shoots of the plant. The bottoms of the yellowish eggs were inserted into the leaf tissue, mainly on its adaxial edge (78.1%). The nymphs hatched and, as they fed on the adaxial side of expanding leaves, modified the cell growth pattern and the round-shape galls developed on the adaxial side with one insect inside. The gall wall showed distinct layers, with the inner one suppliyng the food to the insects, and the outer layer supplying gall protection. Nymphs went through five instars and the exuviae remained stuck on a ball of wax inside the gall. All parasitoids found were Hymenoptera belonging to Chalcidoidea: Eulophidae (1 sp), Pteromalidae (2 spp) and Encyrtidae (3 spp). The findings suggest that leaf gall inducer and parasitoids insects and plant life cycles are closely connected and both leaf sprouting and gall opening seem to be triggered by the same environmental and plant conditions. The high abundance of shoots may favor insect performance as adult individuals can easily find an ideal place for feeding, copulating and laying eggs.

On the term structure of Interbank interest rates: Jump-diffusion processes and option pricing

In this paper we study the dynamic behavior of the term structureof Interbank interest rates and the pricing of options on interest ratesensitive securities. We posit a generalized single factor model withjumps to take into account external influences in the market. Daily datais used to test for jump effects. Qualitative examination of the linkagebetween Monetary Authorities' interventions and jumps are studied. Pricingresults suggests a systematic underpricing in bonds and call options ifthe jumps component is not included. However, the pricing of put optionson bonds presents indeterminacies.

Analysis of secondary growth in the Arabidopsis shoot reveals a positive role of jasmonate signalling in cambium formation.

After primary growth, most dicotyledonous plants undergo secondary growth. Secondary growth involves an increase in the diameter of shoots and roots through formation of secondary vascular tissue. A hallmark of secondary growth initiation in shoots of dicotyledonous plants is the initiation of meristematic activity between primary vascular bundles, i.e. in the interfascicular regions. This results in establishment of a cylindrical meristem, namely the vascular cambium. Surprisingly, despite its major implications for plant growth and the accumulation of biomass, the molecular regulation of secondary growth is only poorly understood. Here, we combine histological, molecular and genetic approaches to characterize interfascicular cambium initiation in the Arabidopsis thaliana inflorescence shoot. Using genome-wide transcriptional profiling, we show that stress-related and touch-inducible genes are up-regulated in stem regions where secondary growth takes place. Furthermore, we show that the products of COI1, MYC2, JAZ7 and the touch-inducible gene JAZ10, which are components of the JA signalling pathway, are cambium regulators. The positive effect of JA application on cambium activity confirmed a stimulatory role of JA in secondary growth, and suggests that JA signalling triggers cell divisions in this particular context.

Solving non-linear stochastic models by parameterizing expectations: An application to asset pricing with production

A new algorithm called the parameterized expectations approach(PEA) for solving dynamic stochastic models under rational expectationsis developed and its advantages and disadvantages are discussed. Thisalgorithm can, in principle, approximate the true equilibrium arbitrarilywell. Also, this algorithm works from the Euler equations, so that theequilibrium does not have to be cast in the form of a planner's problem.Monte--Carlo integration and the absence of grids on the state variables,cause the computation costs not to go up exponentially when the numberof state variables or the exogenous shocks in the economy increase. \\As an application we analyze an asset pricing model with endogenousproduction. We analyze its implications for time dependence of volatilityof stock returns and the term structure of interest rates. We argue thatthis model can generate hump--shaped term structures.

Influência da Imagem Pessoal dos Colaboradores na Construção da Imagem Organizacional – Caso Pratico T+ Telecomunicações

Resumo No cenário global atual, as organizações vêm ganhando consciência do real valor de possuir uma boa imagem perante os seus stakeholders. Esse aspeto faz com que trabalhem na criação de estratégias que lhes possibilite ganhar o maior número de clientes possível e manter os demais públicos afetos a organização satisfeitos. Atualmente o sucesso de qualquer organização depende de diversos fatores que nem sempre podem ser controlados. Mas é papel dos gestores e dos demais colaboradores, tudo fazerem para que esses fatores não criem máculas na imagem da organização o que muitas vezes podem levar ao declínio da organização. A imagem organizacional é um dos elementos que compõem a identidade organizacional de qualquer empresa ou organização e neste sentido nota-se que existe uma ligação bastante estreita entre as duas. Esses dois aspetos são responsáveis pela diversidade de organizações que existem, uma vez que são elementos que as diferenciam umas das outras. Por sua vez a imagem dessa organização é criada através de diversos elementos e os colaboradores são uma peça de extrema importância nesse processo, uma vez que a imagem pessoal e a postura profissional que possuem e adotam, ajudam na construção da imagem organizacional. A cada dia que passa nota-se um crescente interesse por parte dos profissionais em investir na sua imagem e postura profissionais, com o intuito de esses aspetos serem um dos diferenciais que possuem em relação aos demais profissionais existentes no mercado de trabalho. Neste sentido, o objetivo geral desse trabalho é demonstrar de que modo a imagem pessoal dos colaboradores auxilia na construção da imagem organizacional.

The In Vitro Mass-Produced Model Mycorrhizal Fungus, Rhizophagus irregularis, Significantly Increases Yields of the Globally Important Food Security Crop Cassava.

The arbuscular mycorrhizal symbiosis is formed between arbuscular mycorrhizal fungi (AMF) and plant roots. The fungi provide the plant with inorganic phosphate (P). The symbiosis can result in increased plant growth. Although most global food crops naturally form this symbiosis, very few studies have shown that their practical application can lead to large-scale increases in food production. Application of AMF to crops in the tropics is potentially effective for improving yields. However, a main problem of using AMF on a large-scale is producing cheap inoculum in a clean sterile carrier and sufficiently concentrated to cheaply transport. Recently, mass-produced in vitro inoculum of the model mycorrhizal fungus Rhizophagus irregularis became available, potentially making its use viable in tropical agriculture. One of the most globally important food plants in the tropics is cassava. We evaluated the effect of in vitro mass-produced R. irregularis inoculum on the yield of cassava crops at two locations in Colombia. A significant effect of R. irregularis inoculation on yield occurred at both sites. At one site, yield increases were observed irrespective of P fertilization. At the other site, inoculation with AMF and 50% of the normally applied P gave the highest yield. Despite that AMF inoculation resulted in greater food production, economic analyses revealed that AMF inoculation did not give greater return on investment than with conventional cultivation. However, the amount of AMF inoculum used was double the recommended dose and was calculated with European, not Colombian, inoculum prices. R. irregularis can also be manipulated genetically in vitro, leading to improved plant growth. We conclude that application of in vitro R. irregularis is currently a way of increasing cassava yields, that there is a strong potential for it to be economically profitable and that there is enormous potential to improve this efficiency further in the future.

Demonstração dos fluxos de caixa como instrumento de planeamento financeiro e de tomada de decisão

O presente trabalho tem como objectivo evidenciar a importancia da demonstração dos fluxos de caixa como instrumento de planeamento financeiro e de tomada de decisão. As informações fornecida pela demonstração dos fluxos de caixa serão de grande utilidade para a Administração, pois permitem compreender a alocação dos meios financeiros da entidade o que ajudará no planeamento financeiro e na tomada de decisões económico-financeiras. A demonstração dos fluxos de caixa como peça contabilística permite a Administração verificar a consistência dos planos projectados e estimar as exigências financeiras da entidade. O trabalho inclui uma abordagem teórica seguido de um estudo de caso. Na abordagem teórica, fez-se a apresentação das principais teorias e conceitos sobre o tema. O estudo de caso incidiu sobre uma empresa nacional, a Enacol, em que analisou-se a demonstração do fluxo de caixa dos ultimos três anos, bem como os indicadores económicos e financeiros possibilitando a análise da situação financeira da empresa. Foi também utilizada a entrevista a pessoas ligadas a área de contabilidade numa empresa. Os resultados obtidos mostram que a demonstração dos fluxos de caixa é um importante instrumento no planeamento financeiro e na tomada de decisões para a continuidade dos negócios das empresas. This paper aims to highlight the importance of the statement of cash flows as a tool for financial planning and decision making. All the information provided by the statement of cash flows will be very useful for the Administration, because they allow them to understand the allocation of the financial resources of the entity which will be a support in financial planning and decisionmaking in economic and financial areas. Being part of accounting, the statement of cash flows allows the Administration to verify the consistency of the projected plans and estimate the organization financial requirements. The following work includes a theoretical approach followed by a case study. Within the theoretical approach was made a presentation of the main theories and concepts on the subject while the case study focused on a national company, Enacol, in which we analyzed the statement of cash flows for the last three years, as well as the economic and financial indicators enabling the analysis of the financial situation of the company. It was also used an interview used for people connected to a company in the accounting field. Therefore, the results show that the statement of cash flows is an important tool in financial planning and decision making for the continuity of companies businesses.

Sex-mediated herbivory by galling insects on Baccharis concinna (Asteraceae)

The interaction patterns between the dioecious shrub Baccharis concinna Barroso (Asteraceae) and its speciose galling insect community were studied in southeastern Brazil. Two hypotheses were tested in this study: "the differential reproduction and growth hypothesis" that predicts that male plants present fewer reproductive structures and are larger than female plants; and the 'sex-biased herbivory hypothesis' that predicts that male plants support a larger abundance of insect galls than female plants. Plants did not show sexual dimorphism in growth (= mean leaf number). However, male plants had longer shoots and a lower average number of inflorescences than female plants. These results corroborate the hypothesis that male plants grow more and reproduce less than female plants. No statistically significant difference was found in the number of galls between male and female plants, but a sex by environmental effect on gall number was detected. When each species of galling insect was individually analyzed per population of the host plant, the rates of attack varied between sex and population of the host plant, and they were highly variable among the species of galling insects. These results highlight the importance of the interaction between sex and environment in the community structure of galling insects and indicate that other variables besides host sex may influence the patterns of attack by galling herbivores.

Influence of Apion sp. (Brentidae, Apioninae) stem-galls on induced resistance and leaf area of Diospyros hispida (Ebenaceae)

We addressed the influence of the stem galls induced by an unidentified species of Apion sensu lato (Brentidae, Apioninae) on the host plant, Diospyros hispida (Ebenaceae) leaf area and induced resistance against a Cecidomyiidae (Diptera) leaf galls. The study was performed in a cerrado vegetation in Serra do Cipó, southeastern Brazil. Although the number of leaves produced on galled and ungalled shoots did not differ statically (p>0.05), the presence of the apionid galls influenced the area of the leaves on the attacked shoots of D. hispida. Leaves on galled stems were approximately 50% smaller compared to leaves in healthy stems. The average of the cecidomyiid leaf galls successfully induced on healthy shoots was higher compared to galls successfully induced on shoots galled by the apionid. The same pattern was found for the abundance of hypersensitive reactions against the cedidomyiid gall induction. Therefore, the ability of the cecidomyiid to successfully induce galls was not influenced by the apionid galler.

Impact of a gall midge Parkiamyia paraensis (Diptera, Cecidomyiidae) on the Amazonian plant Parkia pendula (Fabaceae)

We observed the occurrence of large numbers of galls induced by Parkiamyia paraensis (Diptera, Cecidomyiidae) on the leaflets of Parkia pendula (Fabaceae) in northern Para, Brazil. We addressed two questions in this study: i) what is the proportion of attacked plants in the field, and nursery conditions?; and ii) what is the impact of galls on the host plant? An average of 86% of the plants were galled in the field. Galled P. pendula were distinct from healthy individuals due to their prostrated architecture and death of terminal shoots. Approximately 50% of the total available leaves and 35% leaflets were attacked by P. paraensis on saplings under nursery conditions. Each one-year old plant supported an average of 1,300 galls, and an average of 60g allocated to galled tissue. Otherwise, attacked individuals were taller and heavier than healthy plants. Attacked plants weighed five times more than healthy plants. When the weight of the galls was removed, the total weight (aerial part without galls) of attacked plants was drastically reduced, indicating that most of the biomass of attacked plants was due to the attack by P. paraensis galls. Although the data indicate a paradox, as young plants attacked by the galling herbivore appear to develop more vigorously than unattacked plants, we suggest that P. paraensis negatively affect P. pendula development.

Relationships between host plant architecture and gall abundance and survival

The plant architecture hypothesis predicts that variation in host plant architecture influences insect herbivore community structure, dynamics and performance. In this study we evaluated the effects of Macairea radula (Melastomataceae) architecture on the abundance of galls induced by a moth (Lepidoptera: Gelechiidae). Plant architecture and gall abundance were directly recorded on 58 arbitrarily chosen M. radula host plants in the rainy season of 2006 in an area of Cerrado vegetation, southeastern Brazil. Plant height, dry biomass, number of branches, number of shoots and leaf abundance were used as predicting variables of gall abundance and larval survival. Gall abundance correlated positively with host plant biomass and branch number. Otherwise, no correlation (p > 0.05) was found between gall abundance with shoot number or with the number of leaves/plant. From a total of 124 galls analyzed, 67.7% survived, 14.5% were attacked by parasitoids, while 17.7% died due to unknown causes. Larvae that survived or were parasitized were not influenced by architectural complexity of the host plant. Our results partially corroborate the plant architecture hypothesis, but since parasitism was not related to plant architecture it is argued that bottom-up effects may be more important than top-down effects in controlling the population dynamics of the galling lepidopteran. Because galling insects often decrease plant fitness, the potential of galling insects in selecting for less architectural complex plants is discussed.

Reporte de datos de madurez sexual de la anchoveta peruana (engraulis ringens) durante el periodo 1961 - 1987

Se presentan datos de madurez sexual promedio mensual de la anchoveta peruana, Engraulis ringens por longitudes y sexos, para las Regiones Norte (06°-10°S), Centro (10°-14° S) y Sur (14°-18°20 ' S) para el período 1961-87. Estos se obtuvieron usando los datos de madurez sexual colectados macroscópicamente de ejemplares procedentes de los desembarques a lo largo del litoral peruano.

Evaluación de los recursos pelágicos: anchoveta, sardina, jurel y caballa en primavera 1989 : Crucero de evaluacion acustica BIC/SNP-1 8911-12 (Chicama - Punta Doña Maria)

Describe los principales resultados obtenidos en el Crucero evaluación de recursos pelágicos, efectuado a bordo del BIC/SNP-1 del 14 de noviembre de 1989, entre Chicama y Punta Doña María, constituyendo la segunda prospección planificada dentro del marco del proyecto Evaluación de los recursos: anchoveta, sardina, jurel y caballa, auspiciado por el Instituto del mar del Perú y la Comunidad económica europea.