Métodos de otimização global aplicados na busca dos parâmetros SRC

O método de empilhamento por Superfície de Reflexão Comum (SRC) produz seções simuladas de afastamento nulo (AN) por meio do somatório de eventos sísmicos dos dados de cobertura múltipla contidos nas superfícies de empilhamento. Este método não depende do modelo de velocidade do meio, apenas requer o conhecimento a priori da velocidade próxima a superfície. A simulação de seções AN por este método de empilhamento utiliza uma aproximação hiperbólica de segunda ordem do tempo de trânsito de raios paraxiais para definir a superfície de empilhamento ou operador de empilhamento SRC. Para meios 2D este operador depende de três atributos cinemáticos de duas ondas hipotéticas (ondas PIN e N), observados no ponto de emergência do raio central com incidência normal, que são: o ângulo de emergência do raio central com fonte-receptor nulo (β₀) , o raio de curvatura da onda ponto de incidência normal (R_PIN) e o raio de curvatura da onda normal (R_N). Portanto, o problema de otimização no método SRC consiste na determinação, a partir dos dados sísmicos, dos três parâmetros (β₀, R_PIN, R_N) ótimos associados a cada ponto de amostragem da seção AN a ser simulada. A determinação simultânea destes parâmetros pode ser realizada por meio de processos de busca global (ou otimização global) multidimensional, utilizando como função objetivo algum critério de coerência. O problema de otimização no método SRC é muito importante para o bom desempenho no que diz respeito a qualidade dos resultados e principalmente ao custo computacional, comparado com os métodos tradicionalmente utilizados na indústria sísmica. Existem várias estratégias de busca para determinar estes parâmetros baseados em buscas sistemáticas e usando algoritmos de otimização, podendo estimar apenas um parâmetro de cada vez, ou dois ou os três parâmetros simultaneamente. Levando em conta a estratégia de busca por meio da aplicação de otimização global, estes três parâmetros podem ser estimados através de dois procedimentos: no primeiro caso os três parâmetros podem ser estimados simultaneamente e no segundo caso inicialmente podem ser determinados simultaneamente dois parâmetros (β₀, R_PIN) e posteriormente o terceiro parâmetro (R_N) usando os valores dos dois parâmetros já conhecidos. Neste trabalho apresenta-se a aplicação e comparação de quatro algoritmos de otimização global para encontrar os parâmetros SRC ótimos, estes são: Simulated Annealing (SA), Very Fast Simulated Annealing (VFSA), Differential Evolution (DE) e Controlled Rando Search - 2 (CRS2). Como resultados importantes são apresentados a aplicação de cada método de otimização e a comparação entre os métodos quanto a eficácia, eficiência e confiabilidade para determinar os melhores parâmetros SRC. Posteriormente, aplicando as estratégias de busca global para a determinação destes parâmetros, por meio do método de otimização VFSA que teve o melhor desempenho foi realizado o empilhamento SRC a partir dos dados Marmousi, isto é, foi realizado um empilhamento SRC usando dois parâmetros (β₀, R_PIN) estimados por busca global e outro empilhamento SRC usando os três parâmetros (β₀, R_PIN, R_N) também estimados por busca global.

Inversion method for obtaining electrical parameters for soil in the rural region in Brazil

This paper presents an inversion methodology through weighted least squares to obtain the electrical parameters for the soil of a typical mid-western region in Brazil using the model based in the formalism of the parabolic equations to calculate the electric field intensity received. To validate this methodology, the results of the radio signal measurement campaign conducted in six radial routes leaving the city of Brasilia, Federal District, where the transmitter was located, were used. The measurements were compared to computer simulations and, thus, the optimal values for the electric conductivity and relative permittivity for the soil of the region could be estimated. Finally, a quantitative analysis of these parameters was performed with the values found in the literature, which demonstrated the effectiveness of the proposed methodology.

Long-term carbon loss in fragmented Neotropical forests

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

Digit systems over commutative rings

Let epsilon be a commutative ring with identity and P is an element of epsilon[x] be a polynomial. In the present paper we consider digit representations in the residue class ring epsilon[x]/(P). In particular, we are interested in the question whether each A is an element of epsilon[x]/(P) can be represented modulo P in the form e(0)+ e(1)x + ... + e(h)x(h), where the e(i) is an element of epsilon[x]/(P) are taken from a fixed finite set of digits. This general concept generalizes both canonical number systems and digit systems over finite fields. Due to the fact that we do not assume that 0 is an element of the digit set and that P need not be monic, several new phenomena occur in this context.

The genomes of two key bumblebee species with primitive eusocial organization

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

Genomic signatures of evolutionary transitions from solitary to group living

The evolution of eusociality is one of the major transitions in evolution, but the underlying genomic changes are unknown. We compared the genomes of 10 bee species that vary in social complexity, representing multiple independent transitions in social evolution, and report three major findings. First, many important genes show evidence of neutral evolution as a consequence of relaxed selection with increasing social complexity. Second, there is no single road map to eusociality; independent evolutionary transitions in sociality have independent genetic underpinnings. Third, though clearly independent in detail, these transitions do have similar general features, including an increase in constrained protein evolution accompanied by increases in the potential for gene regulation and decreases in diversity and abundance of transposable elements. Eusociality may arise through different mechanisms each time, but would likely always involve an increase in the complexity of gene networks.

In situ sonochemical synthesis of ZnO particles embedded in a thermoplastic matrix for biomedical applications

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

Histologia do fígado de tilápia do Nilo (Oreochromis niloticus) alimentados com dietas contendo silagem biológica de pescado

This study aimed to evaluate possible histopathological liver of tilapia fed diets containing fish silage and level protein. Sample of 180 fed with tilapia fingerlings fed with diets containing three protein levels (20, 24 and 28% CP), and Proportions residue fermented silage of tilapia (1/4 and 1/2) of were analyzed during 75 days. The tissue fragments were fixed in Bouin and included in Histosec (R). After that, between 2 to 5 mu m slices were done in a rotation microtome. The methods used for tissue analysis were hematoxilin/eosin and PAS. The histological slices were examined under light microscope (Olympus BX-50). The disarray in the morphology of the liver of fish fed biological silage was influenced by high protein levels, and increased proportions of 1/2 of animal protein diets. It was observed that the variation of hepatocytes is directly related to the type of diet for fish. In fish fed diets containing 28% CP, the liver showed disruption of the structure cordon of hepatocytes, necrosis and shifting points of the core to the periphery. Elevated levels of biological fish silage cause deleterious changes in the liver. The level of protein required to maintain the health of the associated development fish is 24% crude protein.

Influences of the pH on the adsorption properties of an antimicrobial peptide on titanium surfaces

The adsorption behavior of the Tet-124 antimicrobial peptide and the Tet-124 peptide modified at the C- and N-terminus with the sequence glycine-3,4-dihydroxyphenylalanine-glycine (G-DOPA-G) on titanium surfaces was studied using quartz crystal micro balance with dissipation (QCM-D). At a low pH level (4.75) Tet-124 and Tet-124-G-DOPA-G form rigid layers. This is attributed to the electrostatic interactions of the positively charged lysine and arginine residues in the peptide sequence with the negatively charged titanium oxide layer. At an elevated pH level (6.9) Tet-124 shows a lower mass adsorption at the surface than Tet-124-G-DOPA-G. This is attributed to the interaction of the catechol due to the formation of complexes with the titanium oxide and titanium surface layer. The C terminal and N terminal modification with the sequence G-DOPA-G shows similar adsorption rate and mass adsorption coverage at saturation; however it is presented a more loosely layers on the G-DOPA-G-TeT-124. Fibroblast adhesion and the biocompatibility test of both the surfaces following modification with Tet-124-G-DOPA-G and the titanium alloy control showed similar results. In addition, no changes in the adhesion of E. coli bacteria due to the modification of the surface were detected.

Association of Borrelia garinii and B. valaisiana with Songbirds in Slovakia

In Europe, 6 of the 11 genospecies of Borrelia burgdorferi sensu lato are prevalent in questing Ixodes ricinus ticks. In most parts of Central Europe, B. afzelii, B. garinii, and B. valaisiana are the most frequent species, whereas B. burgdorferi sensu stricto, B. bissettii, and B. lusitaniae are rare. Previously, it has been shown that B. afzelii is associated with European rodents. Therefore, the aim of this study was to identify reservoir hosts of B. garinii and B. valaisiana in Slovakia. Songbirds were captured in a woodland near Bratislava and investigated for engorged ticks. Questing I. ricinus ticks were collected in the same region. Both tick pools were analyzed for spirochete infections by PCR, followed by DNA-DNA hybridization and, for a subsample, by nucleotide sequencing. Three of the 17 captured songbird species were infested with spirochete-infected ticks. Spirochetes in ticks that had fed on birds were genotyped as B. garinii and B. valaisiana, whereas questing ticks were infected with B. afzelii, B. garinii, and B. valaisiana. Furthermore, identical ospA alleles of B. garinii were found in ticks that had fed on the birds and in questing ticks. The data show that songbirds are reservoir hosts of B. garinii and B. valaisiana but not of B. afzelii. This and previous studies confirm that B. burgdorferi sensu lato is host associated and that this bacterial species complex contains different ecotypes.

Molecular epidemiology of the SH (small hydrophobic) gene of human respiratory syncytial virus (HRSV), over 2 consecutive years

Human respiratory syncytial virus (HRSV) strains were isolated from nasopharyngeal aspirates collected from 965 children between 2004 and 2005, yielding 424 positive samples. We sequenced the small hydrophobic protein (SH) gene of 117 strains and compared them with other viruses identified worldwide. Phylogenetic analysis showed a low genetic variability among the isolates but allowed us to classify the viruses into different genotypes for both groups, HRSVA and HRSVB. It is also shown that the novel BA-like genotype was well segregated from the others, indicating that the mutations are not limited to the G gene. (C) 2011 Elsevier B.V. All rights reserved.

Development and evolution of caste dimorphism in honeybees - a modeling approach

The difference in phenotypes of queens and workers is a hallmark of the highly eusocial insects. The caste dimorphism is often described as a switch-controlled polyphenism, in which environmental conditions decide an individual's caste. Using theoretical modeling and empirical data from honeybees, we show that there is no discrete larval developmental switch. Instead, a combination of larval developmental plasticity and nurse worker feeding behavior make up a colony-level social and physiological system that regulates development and produces the caste dimorphism. Discrete queen and worker phenotypes are the result of discrete feeding regimes imposed by nurses, whereas a range of experimental feeding regimes produces a continuous range of phenotypes. Worker ovariole numbers are reduced through feeding-regime-mediated reduction in juvenile hormone titers, involving reduced sugar in the larval food. Based on the mechanisms identified in our analysis, we propose a scenario of the evolutionary history of honeybee development and feeding regimes.

Carbohydrate supplementation increases intramyocellular lipid stores in elite runners

The objective was to determine the effects of carbohydrate (CHO) supplementation on exercise-induced hormone responses and post-training intramyocellular lipid stores (IMCL). Twenty-four elite male athletes (28.0 +/- 1.2 years) were randomized to receive CHO (maltodextrin solution) or zero energy placebo solution (control group). The high-intensity running protocol consisted of 10 x 800 m at 100% of the best 3000-m speed (Vm3 km) and 2 x 1000 m maximal bouts in the morning and a submaximal 10-km continuous easy running in the afternoon of day 9. IMCL concentrations were assessed by H-1-MRS before (-day 9) and after training (day 9) in soleus (SO) and tibialis anterior (TA) muscles. Blood hormones were also measured before, during, and post-exercise. The percent change (Delta%) in TA-IMCL was higher in the CHO group (47.9 +/- 24.5 IMCL/Cr) than in the control group (-1.7 +/- 13.1, respectively) (P=.04). Insulin concentrations were higher in the CHO group post-intermittent running compared to control (P=.02). Circulating levels of free fatty acids and GH were lower in the CHO group (P>.01). The decline in performance in the 2nd 1000-m bout was also attenuated in this group compared to control (P<.001 and P=.0035, respectively). The hormonal milieu (higher insulin and lower GH levels) in the CHO group, together with unchanged free fatty acid levels, probably contributed to the increased IMCL stores. This greater energy storage capacity may have improved post-exercise recovery and thus prevented performance deterioration. (C) 2012 Elsevier Inc. All rights reserved.

Negative and positive predictive values of nerve monitoring in thyroidectomy

Background Recurrent nerve injury is 1 of the most important complications of thyroidectomy. During the last decade, nerve monitoring has gained increasing acceptance in several centers as a method to predict and to document nerve function at the end of the operation. We evaluated the efficacy of a nerve monitoring system in a series of patients who underwent thyroidectomy and critically analyzed the negative predictive value (NPV) and positive predictive value (PPV) of the method. Methods. NIM System efficacy was prospectively analyzed in 447 patients who underwent thyroidectomy between 2001 and 2008 (366 female/81 male; 420 white/47 nonwhite; 11 to 82 years of age; median, 43 years old). There were 421 total thyroidectomies and 26 partial thyroidectomies, leading to 868 nerves at risk. The gold standard to evaluate inferior laryngeal nerve function was early postoperative videolaryngoscopy, which was repeated after 4 to 6 months in all patients with abnormal endoscopic findings. Results. At the early evaluation, 858 nerves (98.8%) presented normal videolaryngoscopic features after surgery. Ten paretic/paralyzed nerves (1.2%) were detected (2 unexpected unilateral paresis, 2 unexpected bilateral paresis, 1 unexpected unilateral paralysis, 1 unexpected bilateral paralyses, and 1 expected unilateral paralysis). At the late videolaryngoscopy, only 2 permanent nerve paralyses were noted (0.2%), with an ultimate result of 99.8% functioning nerves. Nerve monitoring showed absent or markedly reduced electrical activity at the end of the operations in 25/868 nerves (2.9%), including all 10 endoscopically compromised nerves, with 15 false-positive results. There were no false-negative results. Therefore, the PPV was 40.0%, and the NPV was 100%. Conclusions. In the present series, nerve monitoring had a very high PPV but a low NPV for the detection of recurrent nerve injury. (C) 2011 Wiley Periodicals, Inc. Head Neck 34: 175-179, 2012