Investing to survive in a duopoly model

We present deterministic dynamics on the production costs of Cournot competitions, based on perfect Nash equilibria of nonlinear R&D investment strategies to reduce the production costs of the firms at every period of the game. We analyse the effects that the R&D investment strategies can have in the profits of the firms along the time. We show that small changes in the initial production costs or small changes in the parameters that determine the efficiency of the R&D programs or of the firms can produce strong economic effects in the long run of the profits of the firms.

Capillaria hepatica-induced septal fibrosis in rats: a contribution to the study of liver fibrogenesis

INTRODUCTION: Septal fibrosis of the liver regularly develops in rats infected with the nematode Capillaria hepatica. Curative treatment of the infection prevents the development of septal fibrosis when intervention occurs up to postinfection day (PID) 15, but not later. The present investigation aimed to demonstrate which parasitic factors are present when the process of septal fibrosis can no longer be prevented by curative treatment. METHODS: Wistar rats were infected with 600 embryonated eggs of C. hepatica administered by gavage and treated with ivermectin and mebendazole in separate groups at PIDs 10, 12, 15, 17 or 20. Rats from each group and their nontreated controls, were killed and examined 40 days after the end of treatment. RESULTS: Findings by PID 15 were compatible with the stage of complete maturation of infection, when worms and eggs were fully developed and a complex host-parasite multifocal necroinflammatory reaction showed greater intensity, but with no signs of septal fibrosis, which appeared from PID 17 onward. CONCLUSIONS: Since the worms spontaneously died by PID 15, not only septal fibrosis production, but also its maintenance and further development appeared dependent on the presence of eggs, which were the only parasitic factor remaining thereafter.

Evolutionary dynamics of Chlamydia trachomatis genome and identification of molecular patterns of hypothetical protein coding genes

The obligate intracellular bacterium Chlamydia trachomatis is a human pathogen of major public health significance. Strains can be classified into 15 main serovars (A to L3) that preferentially cause ocular infections (A-C), genital infections (D-K) or lymphogranuloma venereum (LGV) (L1-L3), but the molecular basis behind their distinct tropism, ecological success and pathogenicity is not welldefined. Most chlamydial research demands culture in eukaryotic cell lines, but it is not known if stains become laboratory adapted. By essentially using genomics and transcriptomics, we aimed to investigate the evolutionary patterns underlying the adaptation of C. trachomatis to the different human tissues, given emphasis to the identification of molecular patterns of genes encoding hypothetical proteins, and to understand the adaptive process behind the C. trachomatis in vivo to in vitro transition. Our results highlight a positive selection-driven evolution of C. trachomatis towards nichespecific adaptation, essentially targeting host-interacting proteins, namely effectors and inclusion membrane proteins, where some of them also displayed niche-specific expression patterns. We also identified potential "ocular-specific" pseudogenes, and pointed out the major gene targets of adaptive mutations associated with LGV infections. We further observed that the in vivo-derived genetic makeup of C. trachomatis is not significantly compromised by its long-term laboratory propagation. In opposition, its introduction in vitro has the potential to affect the phenotype, likely yielding virulence attenuation. In fact, we observed a "genital-specific" rampant inactivation of the virulence gene CT135, which may impact the interpretation of data derived from studies requiring culture. Globally, the findings presented in this Ph.D. thesis contribute for the understanding of C.trachomatis adaptive evolution and provides new insights into the biological role of C. trachomatishypothetical proteins. They also launch research questions for future functional studies aiming toclarify the determinants of tissue tropism, virulence or pathogenic dissimilarities among C. trachomatisstrains.

Ambulatory blood pressure monitoring and microalbuminuria in normotensive subjects with insulin-dependent diabetes mellitus

OBJECTIVE: To assess the association between microalbuminuria with ambulatory blood pressure monitoring in normotensive individuals with insulin-dependent diabetes mellitus. METHODS: Thirty-seven patients underwent determination of the rate of urinary excretion of albumin through radioimmunoassay and ambulatory blood pressure monitoring. Their mean age was 26.5±6.7 years, and the mean duration of their disease was 8 (1-34) years. Microalbuminuria was defined as urinary excretion of albumin > or = 20 and <200µg/min in at least 2 out of 3 urine samples. RESULTS: Nine (24.3%) patients were microalbuminuric. Ambulatory blood pressure monitoring in the microalbuminuric patients had higher mean pressure values, mainly the systolic pressure, during sleep as compared with that in the normoalbuminuric patients (120.1±8.3 vs 110.8±7.1 mmHg; p=0.007). The pressure load was higher in the microalbuminuric individuals, mainly the systolic pressure load during wakefulness [6.3 (2.9-45.9) vs 1.6 (0-16%); p=0.001]. This was the variable that better correlated with the urinary excretion of albumin (rS=0.61; p<0.001). Systolic pressure load >50% and diastolic pressure load > 30% during sleep was associated with microalbuminuria (p=0.008). The pressure drop during sleep did not differ between the groups. CONCLUSION: Microalbuminuric normotensive insulin-dependent diabetic patients show greater mean pressure value and pressure load during ambulatory blood pressure monitoring, and these variables correlate with urinary excretion of albumin.

Escore de cálcio na avaliação da aterosclerose em pacientes com HIV/AIDS

FUNDAMENTO: A terapia antirretroviral aumentou drasticamente a expectativa de vida em pacientes com HIV/AIDS, embora a aterosclerose esteja associada a uma terapia de longo prazo. OBJETIVO: Investigar a prevalência de aterosclerose em pacientes com AIDS submetidos à terapia antirretroviral e a influência de tratamentos de diferentes regimes e durações. MÉTODOS: Pacientes com HIV/AIDS foram abordados durante consultas de rotina. Aqueles que estiveram em terapia antirretroviral por, pelo menos, dois anos tiveram o sangue coletado para análise do perfil lipídico e da glicemia em jejum e foram submetidos à tomografia computadorizada cardíaca para quantificação do escore de cálcio dentro de seis dias, no máximo. A aterosclerose foi definida como escore de cálcio maior que zero (CAC > 0). Fatores de risco tradicionais, síndrome metabólica e o escore de Framingham foram analisados. RESULTADOS: Cinquenta e três pacientes realizaram tomografia computadorizada cardíaca: 50,94% eram do sexo masculino, com idade média de 43,4 anos; 20% tinham hipertensão; 3,77% tinham diabetes; 67,92% tinham hipercolesterolemia; 37,74% tinham hipertrigliceridemia; 47,17% tinham HDL baixo; 24,53% atenderam aos critérios para síndrome metabólica; 96,23% foram classificados no escore de Framingham como "baixo risco"; e 18,87% eram tabagistas. A duração média do tratamento antirretroviral foi de 58,98 meses. A aterosclerose coronária ocorreu em 11 pacientes (20,75%). A duração da terapia antirretroviral não se relacionou à aterosclerose (p = 0,41), e não houve diferenças significativas entre os diferentes esquemas antirretrovirais (p = 0,71). Entre os fatores de risco tradicionais, o tabagismo (OR = 27,20; p = 0,023) e a idade (OR = 20,59; p = 0,033) foram significativos na presença de aterosclerose. Havia tendência para uma associação positiva da aterosclerose com a hipercolesterolemia (OR = 8,30; p = 0,0668). CONCLUSÃO: Os fatores associados à aterosclerose foram idade, tabagismo e hipercolesterolemia. A duração e o tipo de terapia antirretroviral não influenciaram a prevalência da aterosclerose.

Ocorrência de nematódeos do gênero Ditylenchus em tubérculos de batatinha no Est. de São Paulo

Irish potato tubers imported from Holland and Germany were planted at the Instituto Agronômico Experiment Station, Campinas, in April, 1955. At digging time, in July, 1955, the tubers were found to be injured by nematodes belonging to the genus Ditylenchus. No visible symptoms were found on the plants during the growing season, since the nematodes did not attack the stems. However, prevailing weather conditions from April to July were not favorable for nema activities, with low temperature and rain precipitation. Therefore, it does not seem safe to assume that, as a rule, the nemas do not attack buds and stems, for further observations may reveal such an occurrence, as it has been reported in the literature. The injury was characterized by spots consisting of decaying brown tissue, the nematodes being found mainly between this and the uninjured tissue. Larvae and adults occurred simultaneously. Fourteen different potato varieties were attacked by the nematodes, the percentage of disfigured tubers ranging from 6 (vars. Irene, Barima and Tedria) to 38 (var. Stamm 456). Studies en the morphology cf the parasites disclosed that two different Ditylenchus forms were present, with Apheten-chus sp. and Aphelenchoides sp. associated with them. The writers have not yet drawn a final conclusion about the identification of the Ditylenchi. However, it was clearly seen that no form can be identified either with D. dipsaci or with D. destructor. Both forms have lateral fields made up of 6 incisures, what separates them from D. dipsaci. On the other hand, measurements as well as some details in the organization of the oesophagus make the identification with D. destructor quite impossible. As far as the origin of the parasites is concerned, the fact that they could not be determined either as D. dipsaci or as D. destructor emphasizes the possibility of being two native species, not introduced with the tubers imported.

La Perspectiva biofísica de la relació home-natura: economia ecològica

L'estudi de la relació entre l'activitat econòmica i el medi que ens envolta és antiga en economia. No obstant és cert que darrerament la teoria econòmica sembla haver-la oblidada. És per això que quan sortí la disciplina que avui s’anomena "economia ecològica" va implicar una ruptura amb la manera amb la qual la teoria econòmica convencional descrivia nostra relació amb el medi ambient. El present capítol pretén descriure breument el que creiem són les característiques principals que la fan diferent de la resta de disciplines: la inconmensurabilitat de valors, la seva anàlisi en termes biofísics, i les seves repercussions al nivell de la generació de polítiques, que la fan ser un exemple del que es coneix com a ciència post-normal.

Behavior of triatomines (Hemiptera, Reduviidae) vectors of Chagas' disease. II. Influence of feeding, lighting and time of day on the number of mating, mating speed and duration of copulation of Panstrongylus megistus (Burm, 1835) under laboratory conditions

To determine in influence of feeding, lighting and time of day on the copulating behavior of Panstrongylus megistus, 480 insect pairs were divided into four groups of 120 each and tested in the following respective situations: without food deprivation (F.D.), with five days of F.D., with ten days of F.D., and with 20 days of F. D. The tests were performed between 9:00 a.m. to 12:00a.m. and 7:00 p.m. to 10:00 p.m., with light (700-1400 lux) and in the dark (1.4-2.8 lux) and behavior was recorded by the time sampling technique. Mating spped (MS) and duration of copulation (DC) were also calculated for each situation. The maximum frequency of copulation was observed after five days of F.D., at night, in the dark (n = 16), and the minimum was observed for recently-fed pairs, at night, with light (n = 4). Males approached females more often than females approached males. MS was lowest in pairs with twenty days of F.D., at night, with light (X = 23.0 ± 16.0 minutes), and highest in recently-fed pairs, during the day, with light (X = 2.9 ± 2.5 minutes). DC was shortest in recently-fed insects, during the day, in the dark (X = 23.5 ± 6.7 minutes), and longest in recently-fed animals, at night, in the dark (X = 38.3 ± 6.9 minutes).

Indirect costs of parasitism are shaped by variation in the type of immune challenge and food availability

Parasites can inflict indirect fitness costs to their hosts by eliciting costly immune responses. These costs depend on the type and amount of immunostimulants presented to the host immune system but also on the amount of resources available to fuel host immune responses. Here, we investigated how the relative costs of two different types of immune challenge are modulated by variation in food availability. We injected nestling tawny owls (Strix aluco) with either 10 mu g of phytohaemagglutinin (PHA) or 20 mu g of lipopolysaccharide (LPS), and subsequently raised them under two different food regimes (food-restricted vs. ad libitum). After controlling for food consumption, we found that LPS-injected nestlings lost more body mass than PHA-injected ones only when food-restricted. We also found that body mass gain of owlets fed ad libitum decreased with the intensity of the skin swelling response against LPS, but not PHA. These experimental and correlative results suggest that nestling tawny owls suffered greater immune costs when treated with LPS than PHA, and that variation in the costs of two different types of immune challenge can be exacerbated under conditions of low food availability. Our study highlights the importance of taking into consideration the interplay between host immunity and nutrition in the study of indirect costs of parasitism.

Pharmacological screening of plants recommended by folk medicine as anti-snake venom: I. Analgesic and anti-inflammatory activities

We have observed that several plants used popularly as anti-snake venom show anti-inflammatory activity. From the list prepared by Rizzini, Mors and Pereira some species have been selected and tested for analgesic activity (number of contortions) and anti-inflammatory activity (Evans blue dye diffusion - 1% solution) according to Whittle's technique (intraperitoneal administration of 0.1 N-acetic acid 0.1 ml/10 g) in mice. Previous oral administration of a 10% infusion (dry plant) or 20% (fresh plant) corresponding to 1 or 2 g/Kg of Apuleia leiocarpa, Casearia sylvestris, Brunfelsia uniflora, Chiococca brachiata, Cynara scolymus, Dorstenia brasiliensis, Elephantopus scaber, Marsypianthes chamaedrys, Mikania glomerata and Trianosperma tayuya demonstrated analgesic and/or anti-inflammatory activities of varied intensity

Information Dispersion and Equilibrium Multiplicity

This paper studies the implications of correlation of private signals about the liquidation value of a risky asset in a variation of a standard noisy rational expectations model in which traders receive endowment shocks which are private information and have a common component. We Â…nd that a necessary condition to generate multiple linear partially revealing rational expectations equilibria is the existence of several sources of information dispersion. In this context equilibrium multiplicity tends to occur when information is more dispersed. A necessary condition to have strategic complementarity in information acquisition is to have mul- tiple equilibria. When the equilibrium is unique there is strategic substi- tutability in information acquisition, corroborating the result obtained in Grossman and Stiglitz (1980). JEL ClassiÂ…cation: D82, D83, G14 Keywords: Multiplicity of equilibria, strategic complementarity, asym- metric information.

Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial.

OBJECTIVE: To determine the subjective response to iron therapy in non-anaemic women with unexplained fatigue. DESIGN: Double blind randomised placebo controlled trial. SETTING: Academic primary care centre and eight general practices in western Switzerland. PARTICIPANTS: 144 women aged 18 to 55, assigned to either oral ferrous sulphate (80 mg/day of elemental iron daily; n=75) or placebo (n=69) for four weeks. MAIN OUTCOME MEASURES: Level of fatigue, measured by a 10 point visual analogue scale. RESULTS: 136 (94%) women completed the study. Most had a low serum ferritin concentration; <or= 20 microg/l in 69 (51%) women. Mean age, haemoglobin concentration, serum ferritin concentration, level of fatigue, depression, and anxiety were similar in both groups at baseline. Both groups were also similar for compliance and dropout rates. The level of fatigue after one month decreased by -1.82/6.37 points (29%) in the iron group compared with -0.85/6.46 points (13%) in the placebo group (difference 0.95 points, 95% confidence interval 0.32 to 1.62; P=0.004). Subgroups analysis showed that only women with ferritin concentrations <or= 50 microg/l improved with oral supplementation. CONCLUSION: Non-anaemic women with unexplained fatigue may benefit from iron supplementation. The effect may be restricted to women with low or borderline serum ferritin concentrations.

Partial inhibition of hemocyte agglutination by Lathyrus odoratus lectin in Crassotrea virginica infected with Perkinsus marinus

Quantitative determinations of agglutination of hemocytes from oysters, Crassostrea virginica, by the Lathyrus odoratus lectin at five concentrations revealed that clumping of hemocytes from oysters infected with Perkinsus marinus is partially inhibited. Although the nature of the hemocyte surface saccharide, which is not D(+)-glucose, D(+)mannose, or alpha-methyl-D-mannoside, remains to be determined, it may be concluded that this molecule also occurs on the surface of P. marinus. It has been demonstrated that the panning technique (Ford et al. 1990) is qualitatively as effective for determining the presence of P. marinus in C. virginica as the hemolymph assay method (Gauthier & Fisher 1990).

Sleep disorders in children with cerebral palsy.

To determine the frequency and predictors of sleep disorders in children with cerebral palsy (CP) we analyzed the responses of 173 parents who had completed the Sleep Disturbance Scale for Children. The study population included 100 males (57.8%) and 73 females (42.2%; mean age 8y 10mo [SD 1y 11mo]; range 6y-11y 11mo). Eighty-three children (48.0%) had spastic diplegia, 59 (34.1%) congenital hemiplegia, 18 (10.4%) spastic quadriplegia, and 13 (7.5%) dystonic/dyskinetic CP. Seventy-three children (42.2%) were in Gross Motor Function Classification System Level I, 33 (19.1%) in Level II, 30 (17.3%) in Level III, 23 (13.3%) in Level IV, and 14 (8.1%) in Level V. Thirty children (17.3%) had epilepsy. A total sleep problem score and six factors indicative of the most common areas of sleep disorder in childhood were obtained. Of the children in our study, 23% had a pathological total sleep score, in comparison with 5% of children in the general population. Difficulty in initiating and maintaining sleep, sleep-wake transition, and sleep breathing disorders were the most frequently identified problems. Active epilepsy was associated with the presence of a sleep disorder (odds ratio [OR]=17.1, 95% confidence interval [CI] 2.5-115.3), as was being the child of a single-parent family (OR=3.9, 95% CI 1.3-11.6). Disorders of initiation and maintenance of sleep were more frequent in children with spastic quadriplegia (OR=12.9, 95% CI 1.9-88.0), those with dyskinetic CP (OR=20.6, 95% CI 3.1-135.0), and those with severe visual impairment (OR=12.5, 95% CI 2.5-63.1). Both medical and environmental factors seem to contribute to the increased frequency of chronic sleep disorders in children with CP.

On the automatic application of inequality indexes in the analysis of the international distribution of environmental indicators

In recent years traditional inequality measures have been used to quite a considerable extent to examine the international distribution of environmental indicators. One of its main characteristics is that each one assigns different weights to the changes that occur in the different sections of the variable distribution and, consequently, the results they yield can potentially be very different. Hence, we suggest the appropriateness of using a range of well-recommended measures to achieve more robust results. We also provide an empirical test for the comparative behaviour of several suitable inequality measures and environmental indicators. Our findings support the hypothesis that in some cases there are differences among measures in both the sign of the evolution and its size. JEL codes: D39; Q43; Q56. Keywords: international environment factor distribution; Kaya factors; Inequality measurement