Precios de adjudicación y componentes del spread en la Bolsa de Valores de Lima

En este trabajo se analizan tres aspectos del mercado de acciones de la Bolsa de Valores de Lima (bvl): i) la relación de corto plazo entre la dinámica de precios, la dirección y el volumen del flujo de órdenes; ii) los componentes del spread y el punto de equilibrio del Libro de Órdenes Límite por acción, y iii) la dinámica de los precios, de la dirección de la orden y del volumen negociado por shocks de las mismas variables rezagadas. Los resultados econométricos para datos intradiarios del año 2012 muestran que la dinámica de corto plazo de las acciones más líquidas y menos líquidas del Índice General de la bvl se explica por la dirección del flujo de órdenes, cuyo impacto en el precio es temporal en ambos casos.

O trabalho de sísifo: crédito a comerciantes e reprodução do sistema de aviamento (1914-1919/1943-1952)

A relação de crédito, comercialização em espécie e controle do trabalho por endividamento, tida como característica específica da região amazônica, teve similares pelo mundo relacionados a diversas formas de produção: extrativismo vegetal, agricultura familiar, artesanato e mesmo plantations de seringueiras no Sudeste asiático. O monopólio comercial por falta de acesso ao mercado e usual ausência de moedas garante ao comerciante o poder de arbitragem sobre a equivalência de trocas, endividando o produtor que lhe toma adiantado mantimentos e instrumentos em troca da produção futura. A ampliação das relações de financiamento capitalistas com a expansão do sistema bancário em meados do século XX pretendeu desestruturar o sistema de aviamento substituindo o tradicional crédito em espécie, monetarizando a economia, multiplicando o número de comerciantes concorrentes e rompendo o monopólio dos aviadores no sertão. A persistência atual desta relação na Amazônia é explicada por se concretizar como alternativa de integração ao mercado financeiro e de produtos capitalista em uma realidade caracterizada historicamente por unidades de produção dispersas, com precária estrutura de escoamento e comunicação.

Foraging Activity and Seasonal Food Preference of Linepithema micans (Hymenoptera: Formicidae), a Species Associated With the Spread of Eurhizococcus brasiliensis (Hemiptera: Margarodidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Small hospitals matter: insights from the emergence and spread of vancomycin-resistant enterococci in 2 public hospitals in inner Brazil

Although vancomycin-resistant enterococci (VRE) are reported in Brazil since 1996, data on their impact over settings of different complexity are scarce. We performed a study aimed at identifying determinants ofVRE emergence and spread in a public hospital consortium (comprising 2 hospitals, with 318 and 57 beds) in inner Brazil. Molecular typing and case-control studies (addressing predictors of acquisition or clonality) were performed. Among 122 authocthonous isolates, 106 were Enterococcus faecium (22 clones), and 16, Enterococcus faecalis (5 clones). Incidence was greater in the small-sized hospital, and a previous admission to this hospital was associated with greater risk of VRE colonization or infection during admission to the larger one. Overall risk factors included comorbidities, procedures, and antimicrobials (piperacillin-tazobactam, cefepime, and imipenem). Risk factors varied among different hospitals, species, and clones. Our findings demonstrate that VRE can spread within low-complexity facilities and from these to larger hospitals. (C) 2015 Elsevier Inc. All rights reserved.

Allee effects and population spread in patchy landscapes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A Tale of transposition: tn3-like transposons play a major role in the spread of pathogenicity determinants of xanthomonas citri and other xanthomonads

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Spatial and Temporal Spread of Bovine Tuberculosis in Wild White-Tailed Deer in Michigan

In 1975, a wild white-tailed deer infected with bovine tuberculosis was shot in the northeastern Lower Peninsula, Michigan. The shooting of a second infected deer in the same area in 1994 triggered ongoing disease surveillance in the region. By 2002, bovine tuberculosis had been confirmed in 12 Michigan counties: from 449 deer; two elk; 41 non-cervid wildlife; one captive cervid facility and 28 cattle herds. We analyzed geographic spread of disease since the surveillance began and investigated factors influencing the prevalence of disease within the infected area. These analyses reveal that 78 percent of tuberculous deer came from within a 1560 km2 'core' area, within which the prevalence of apparent disease averaged 2.5 percent. Prevalence declined dramatically outside of the core and was an order of magnitude lower 30 km from its boundary. This prevalence gradient was highly significant (P<0.0001) and did not alter over the 6 year surveillance period (P= 0.98). Within the core, deer density and supplemental feeding by hunters were positively and independently correlated with tuberculosis prevalence in deer. Together, these two factors explained 55 percent of the variation in prevalence. We conclude that bovine tuberculosis was already well established in the deer population in 1994, that the infected area has not expanded significantly since that time, and that deer over-abundance and food supplementation have both contributed to ongoing transmission of disease. Managers are currently enforcing prohibitions on deer feeding in the core and are working to lower deer numbers there through increased hunting pressure.

Contributions of demography and dispersal parameters to the spatial spread of a stage-structured insect invasion

Stage-structured models that integrate demography and dispersal can be used to identify points in the life cycle with large effects on rates of population spatial spread, information that is vital in the development of containment strategies for invasive species. Current challenges in the application of these tools include: (1) accounting for large uncertainty in model parameters, which may violate assumptions of ‘‘local’’ perturbation metrics such as sensitivities and elasticities, and (2) forecasting not only asymptotic rates of spatial spread, as is usually done, but also transient spatial dynamics in the early stages of invasion. We developed an invasion model for the Diaprepes root weevil (DRW; Diaprepes abbreviatus [Coleoptera: Curculionidae]), a generalist herbivore that has invaded citrus-growing regions of the United States. We synthesized data on DRW demography and dispersal and generated predictions for asymptotic and transient peak invasion speeds, accounting for parameter uncertainty. We quantified the contributions of each parameter toward invasion speed using a ‘‘global’’ perturbation analysis, and we contrasted parameter contributions during the transient and asymptotic phases. We found that the asymptotic invasion speed was 0.02–0.028 km/week, although the transient peak invasion speed (0.03– 0.045 km/week) was significantly greater. Both asymptotic and transient invasions speeds were most responsive to weevil dispersal distances. However, demographic parameters that had large effects on asymptotic speed (e.g., survival of early-instar larvae) had little effect on transient speed. Comparison of the global analysis with lower-level elasticities indicated that local perturbation analysis would have generated unreliable predictions for the responsiveness of invasion speed to underlying parameters. Observed range expansion in southern Florida (1992–2006) was significantly lower than the invasion speed predicted by the model. Possible causes of this mismatch include overestimation of dispersal distances, demographic rates, and spatiotemporal variation in parameter values. This study demonstrates that, when parameter uncertainty is large, as is often the case, global perturbation analyses are needed to identify which points in the life cycle should be targets of management. Our results also suggest that effective strategies for reducing spread during the asymptotic phase may have little effect during the transient phase. Includes Appendix.

Exploration of the parameter space in an agent-based model of tuberculosis spread: emergence of drug resistance in developing vs developed countries

In this work we present an agent-based model for the spread of tuberculosis where the individuals can be infected with either drug-susceptible or drug-resistant strains and can also receive a treatment. The dynamics of the model and the role of each one of the parameters are explained. The whole set of parameters is explored to check their importance in the numerical simulation results. The model captures the beneficial impact of the adequate treatment on the prevalence of tuberculosis. Nevertheless, depending on the treatment parameters range, it also captures the emergence of drug resistance. Drug resistance emergence is particularly likely to occur for parameter values corresponding to less efficacious treatment, as usually found in developing countries.

Different levels of MT-I/II between patients with MTLE with or without seizure generalization: does hippocampal MT-I/II affects seizure spread, or does seizure spread promotes differential expression of MT-I/II?

In the central nervous system, zinc is released along with glutamate during neurotransmission and, in excess, can promote neuronal death. Experimental studies have shown that metallothioneins I/II (MT-I/II), which chelate free zinc, can affect seizures and reduce neuronal death after status epilepticus. Our aim was to evaluate the expression of MT-I/II in the hippocampus of patients with temporal lobe epilepsy (TLE). Hippocampi from patients with pharmacoresistant mesial temporal lobe epilepsy (MTLE) were evaluated for expression of MT-I/II and for neuronal, astroglial, and microglial populations. Compared to control cases, MTLE group displayed widespread increase in MT-I/II expression, astrogliosis and reduced neuronal population. MT-I/II levels did not correlate with any clinical variables, but patients with secondary generalized seizures (SGS) had less MT-I/II than patients without SGS. In conclusion, MT-I/II expression was increased in hippocampi from MTLE patients and our data suggest that it may be associated with different seizure spread patterns.

Worldwide spread of Dengue virus type 1

BACKGROUND: DENV-1 is one of the four viral serotypes that causes Dengue, the most common mosquito-borne viral disease of humans. The prevalence of these viruses has grown in recent decades and is now present in more than 100 countries. Limited studies document the spread of DENV-1 over the world despite its importance for human health. METHODOLOGY/PRINCIPAL FINDINGS: We used representative DENV-1 envelope gene sequences to unravel the dynamics of viral diffusion under a Bayesian phylogeographic approach. Data included strains from 45 distinct geographic locations isolated from 1944 to 2009. The estimated mean rate of nucleotide substitution was 6.56 × 10⁻⁴ substitutions/site/year. The larger genotypes (I, IV and V) had a distinctive phylogenetic structure and since 1990 they experienced effective population size oscillations. Thailand and Indonesia represented the main sources of strains for neighboring countries. Besides, Asia broadcast lineages into the Americas and the Pacific region that diverged in isolation. Also, a transmission network analysis revealed the pivotal role of Indochina in the global diffusion of DENV-1 and of the Caribbean in the diffusion over the Americas. CONCLUSIONS/SIGNIFICANCE: The study summarizes the spatiotemporal DENV-1 worldwide spread that may help disease control.