bluuebunny/crossref_metadata_2025 huggingface dataset:
Resposta de pastagens perenes à adubação com chorume suíno: pastagem natural
Authors: Scheffer-Basso Simone Meredith , Scherer Clênio Valdeni , Ellwanger Marcelo de Faria
Published: February 2008

Este trabalho foi realizado com o objetivo de verificar a resposta de uma pastagem natural na Depressão Central do Rio Grande do Sul à adubação com chorume suíno nas doses de 0, 15, 30 e 45 m³/ha, equivalentes a 76,8; 153,7 e 230,5 kg N/ha/corte depois de cada um dos quatro cortes, realizados no período de outubro de 2003 e fevereiro de 2004, totalizando 0, 60, 120 e 180 m³/ha de chorume. A massa seca (MS) da pastagem aumentou de forma linear de acordo com as doses de chorume. Na pastagem testemunha, com aplicação de 45 m³/ha/corte, houve aumento de 108% na produção de MS (1.137 kg/ha/corte; 4.549 kg/ha no total dos cortes) e de 42% na altura da pastagem (21 cm) e redução de 8% no conteúdo de fibra em detergente ácido (FDA) (41,8%). A eficiência da aplicação do chorume foi, em média, de 16,9 kg MS/m³/corte. Com as aplicações do fertilizante, verificou-se aumento na concentração de nutrientes no solo (máximo: K = 200 mg/L; P = 52 mg/L; Ca = 1,8 cmol c/dm-3; Mg = 1,4 cmol c/dm-3). A dose de 30 m³/ha/corte pode ser um valor-referência para as pastagens naturais na primavera-verão.
Comportamento sexual de touros Zebuínos e Angus em central de coleta e processamento de sêmen
Authors: Bascuñan Daniela Sartori Rocha , Jorge André Mendes , Rocha Gilberto Pedroso da , Weschler Francisco Stefano , Andrighetto Cristiana
Published: February 2008

O comportamento sexual foi avaliado em 88 touros das raças Angus, Gir, Guzerá e Nelore, com 5 anos de idade, em média, peso médio de 906 kg e circunferência escrotal média de 41 cm, submetidos ao manejo reprodutivo em central de coleta e processamento de sêmen. Os touros da raça Angus apresentaram menor tempo de reação se comparados aos das raças zebuínas. O tipo de estímulo manequim em movimento influenciou positivamente o tempo de reação em todas as raças estudadas. Touros mais velhos tiveram maior tempo de reação em comparação aos mais jovens. A ordem do salto no dia não influenciou o tempo de reação dos touros. Todos os eventos comportamentais dos touros Angus ocorreram próximo ao serviço completo em vagina artificial. Os eventos comportamentais cheirar e lamber genitália, golpear o manequim com a cabeça ou o chifre, gotejamento de líquido seminal, ereção e protusão de pênis e monta abortada foram realizados em maior freqüência pelos touros zebuínos que pelos Angus. Na espécie indiana, os padrões comportamentais contração prepucial e monta abortada foram mais realizados pelos touros Nelore que pelos Guzerá. O evento serviço completo sem arranque final, no entanto, foi mais observado nos Nelore e nos Guzerá que nos touros Gir.
Plasma sangüíneo em pó em dietas para leitões desmamados aos 14 dias de idade
Authors: Gattás Gustavo , Ferreira Aloízio Soares , Barbosa Fellipe Freitas , Silva Francisco Carlos de Oliveira , Donzele Juarez Lopes , Lopes Darci Clementino
Published: February 2008

Foi conduzido um experimento utilizando 128 leitões com peso inicial de 4,32 ± 0,55 kg, desmamados aos 14 dias de idade, distribuídos em delineamento em blocos, composto de quatro tratamentos, oito repetições e quatro animais por unidade experimental, com o objetivo de avaliar níveis de inclusão de plasma sangüíneo em pó (PSP) em dietas para leitões em três períodos consecutivos: 14 a 28 (período 1); 29 a 35 (período 2) e 36 a 42 (período 3) dias de idade. Os níveis de PSP foram de 0,0; 4,0; 6,0 e 8,0% para o período 1; 0,0; 2,8; 4,2 e 5,6% para o período 2 e 0,0; 2,0; 3,0 e 4,0% para o período 3. No período 4 (43 a 56 dias de idade), todos os leitões foram alimentados com dieta isenta de PSP. Durante o período 1, o consumo diário de ração (CDR) e o ganho de peso diário (GPD) foram afetados de forma linear crescente pelos níveis de PSP, entretanto, o modelo Linear Response Plateau foi o que melhor se ajustou aos dados; a partir dele, estimaram-se os níveis de 7,5% de PSP para CDR e de 6,6% para GPD. No período 2, os níveis de PSP não influenciaram essas características de desempenho. No período 3, verificou-se efeito dos níveis de PSP sobre o GPD, que diminuiu de forma linear a medida que os níveis PDP aumentou. Entretanto, não foi constatada diferença no CDR entre os níveis de PSP. Não houve efeito residual dos níveis de PSP sobre o CRD e o GPD no período 4. O nível de inclusão de PSP na dieta de leitões desmamados aos 14 dias de idade é de 7,5% para o período de 14 a 28 dias de idade dos animais.
Desempenho de frangos de corte sob suplementação com ácidos lático, fórmico, acético e fosfórico no alimento ou na água
Authors: Viola Eduardo Spillari , Vieira Sergio Luiz , Torres Cibele Araújo , Freitas Dimitri Moreira de , Berres Josemar
Published: February 2008

Este estudo foi realizado para avaliar os efeitos da suplementação de ácidos orgânicos nas dietas e de ácidos orgânicos e ácido ortofosfórico na água de bebida sobre o desempenho de frangos de corte. Foram utilizadas 2.112 aves divididas em seis tratamentos, cada um com oito repetições. As dietas, exclusivamente vegetais, foram formuladas à base de milho e farelo de soja sem antibióticos ou anticoccidianos. A dieta controle não foi suplementada com ácidos orgânicos. As demais foram suplementadas com misturas de ácidos orgânicos, formuladas para cada fase de crescimento (1 a 7, 8 a 21 e 22 a 35 dias de idade): mistura A: ácidos lático (52%), fórmico (1%) e acético (2%); mistura B: ácidos lático (76%), fórmico (2%) e acético (4%); mistura C: ácidos lático (50%), fórmico (8%) e acético (7%); mistura D: ácido fórmico (85%). A mistura E continha 40% de ácido lático, 5% de ácido acético e 5% de ácido ortofosfórico e foi adicionada à água de bebida. As doses adicionadas nas dietas, por fase, foram: 8,0; 4,5 e 2,5 kg/t para as misturas A, B e C e 2,5; 2,5 e 2,0 kg/t para a mistura D. A mistura E foi utilizada na água de bebida nas doses de 3,0; 2,0; 1,0 kg/1.000 L. O experimento foi conduzido em delineamento completamente casualizado. Houve um benefício geral da suplementação da mistura de ácidos sobre o ganho de peso das aves. Entretanto, não houve diferença na conversão alimentar ao final do estudo. O consumo de alimento foi menor para a mistura B, enquanto o consumo de água foi negativamente afetado pela mistura E fornecida na água. O peso relativo das seções do intestino delgado aos 7 dias de idade foi menor nas aves da dieta controle, enquanto, aos 21 dias de idade, foi menor nas aves alimentadas com a dieta suplementada com as misturas A e C. A mistura E utilizada na água determinou redução no comprimento de jejuno aos 7 dias de idade, enquanto a mistura B teve efeito negativo sobre os comprimentos de íleo e intestino delgado aos 21 dias de idade. Em comparação à dieta controle, sem suplementação de antibióticos promotores de crescimento, as dietas suplementadas com acidificantes foram eficientes em melhorar o ganho de peso de frangos de corte.
Viabilidade econômica, desempenho e características de carcaça de garrotes em confinamento alimentados com dietas contendo silagem de capins tanzânia ou marandu ou silagem de milho
Authors: Coan Rogério Marchiori , Reis Ricardo Andrade , Resende Flávio Dutra de , Sampaio Ricardo Linhares , Schocken-Iturrino Ruben Pablo , Garcia Gisela Rojas , Berchielli Telma Teresinha
Published: February 2008

O experimento foi conduzido com o objetivo de avaliar o desempenho, as características de carcaça e a viabilidade econômica do confinamento de bovinos alimentados com silagem dos capins tanzânia ou marandu, com 0 e 10% de polpa cítrica peletizada (PCP), em comparação à silagem de milho. Foram utilizados silos de superfície (12 × 5 × 1 m) como silos experimentais. O delineamento experimental utilizado foi o inteiramente casualizado, com oito tratamentos (dietas) e seis repetições (animais). As dietas experimentais foram formuladas com os capins tanzânia ou marandu, acrescidos ou não de 10% de PCP, em comparação à silagem de milho e de forma a permitir ganhos de 1,0 e 1,2 kg/dia, respectivamente. Os animais alimentados com as dietas com silagem de capim-marandu e 10% de PCP formuladas para ganhos de peso de 1,0 e 1,2 kg/dia, apresentaram os maiores consumos de MS. Não houve diferença significativa no ganho de peso vivo, no peso de carcaça quente, no rendimento de carcaça, no ganho de carcaça, na espessura de gordura e na área de olho-de-lombo. A taxa de remuneração do capital e a taxa interna de retorno foram maiores nos animais alimentados com as dietas contendo silagem de milho.
Silagem de cana-de-açúcar comparada a fontes tradicionais de volumosos suplementares no desempenho de vacas de alta produção
Authors: Queiroz Oscar Cezar Muller , Nussio Luiz Gustavo , Schmidt Patrick , Ribeiro José Leonardo , Santos Mateus Castilho , Zopollatto Maity
Published: February 2008

O experimento foi conduzido com o objetivo de avaliar o desempenho de animais de alta produção alimentados com rações com diferentes fontes de volumosos. Foram availados os seguintes tratamentos: cana-de-açúcar in natura (CA); silagem de cana-de-açúcar inoculada com L. buchneri (SCA); silagem de milho (SM); e mistura de cana-de-açúcar in natura e silagem de milho (CASM). O experimento foi conduzido em quadrado latino 4×4 com períodos de 21 dias, de modo que, nos sete últimos dias, realizou-se a coleta de amostras. Além da avaliação de desempenho, foram feitas análises bromatológicas dos volumosos, das rações e das sobras e análises da composição do leite e da estabilidade aeróbia dos volumosos e das rações. Observaram-se diferenças quanto ao consumo de MS, que foi maior quando os animais foram alimentados com a SCA (23,5 kg/dia) e a CASM (23,5 kg/dia). Todas as rações propiciaram aos animais elevada produção leiteira (24,4 a 25,5 kg/dia), que não diferiu entre os volumosos. A composição do leite variou somente quanto ao teor de gordura, que foi maior quando os animais foram alimentados com SM (36,1%) e CASM (34,8%). Os resultados de estabilidade aeróbia comprovaram efeito positivo da aditivação bacteriana na SCA, que apresentou a maior estabilidade entre os volumosos (13,63 horas). A ração contendo SM como fonte de volumoso apresentou a menor estabilidade, o que provavelmente explica o baixo consumo dos animais nesse tratamento. A SCA é uma alternativa tecnicamente viável à utilização da planta in natura e ambas podem proporcionar elevadas produções de leite, desde que as rações sejam corretamente balanceadas. A inoculação com L. buchneri melhorou o valor nutritivo e reduziu as perdas fermentativas.
Ludomania: avaliação transcultural do jogo de azar por dinheiro e seu tratamento
Authors: Weinstock Jeremiah , Ledgerwood David M , Modesto-Lowe Vania , Petry Nancy M
Published: February 2008

O jogo patológico é um transtorno do controle do impulso que está ganhando mais e mais atenção. Este artigo revisa os critérios diagnósticos e os instrumentos de rastreamento para o jogo patológico, bem como os índices de prevalência desse transtorno ao redor do mundo, com ênfase na situação do jogo de azar no Brasil. Os tratamentos para o jogo patológico são também descritos, incluindo tanto as abordagens psicossociais como as farmacológicas. O jogo patológico é altamente comórbido com outros transtornos psiquiátricos, incluindo abuso de substâncias e depressão e poucos jogadores patológicos buscam tratamento para seus problemas com o jogo de azar. Portanto, recomenda-se a procura direta de problemas com o jogo de azar. É necessário melhorar a educação sobre o transtorno, tanto sob a perspectiva do cuidador como da sociedade, a fim de reduzir as conse-qüências pessoais e sociais desse transtorno.
Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna
Authors: Scheibler DR. , Christoff AU.
Published: February 2008

We inventoried terrestrial small mammals in an agricultural area in southern Brazil by using trapping and prey consumed by Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus). Small mammals were trapped in three habitat types: corn fields, uncultivated fields ("capoeiras"), and native forest fragments. A total of 1,975 small mammal specimens were trapped, another 2,062 identified from the diet of Barn Owls, and 2,066 from the diet of White-tailed Kites. Both trapping and prey in the predators' diet yielded 18 small mammal species: three marsupials (Didelphis albiventris, Gracilinanus agilis, and Monodelphis dimidiata) and 15 rodents (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus, and Rattus rattus (Linnaeus, 1758)). The greatest richness was found in the uncultivated habitat. We concluded that the three methods studied for inventorying small mammals (prey in the diet of Barn Owls, White-tailed Kites, and trapping) were complementary, since together, rather than separately, they produced a better picture of local richness.
Dietary tissue cadmium accumulation in an amazonian teleost (Tambaqui, Colossoma macropomum Cuvier, 1818)
Authors: Matsuo AYO. , Val AL.
Published: February 2008

Understanding the effects of metal contamination in the Amazon basin is important because of the potential impact on this region of high biodiversity. In addition, the significance of fish as the primary source of protein for the local human population (living either alongside the Amazon River or in the city of Manaus) highlights the need for information on the metal transfer through the food chain. Bioaccumulation of metals in fish can occur at significant rates through the dietary route, without necessarily resulting in death of the organism. The goal of this work was to expose an economic relevant species from the Amazon basin (tambaqui, Colossoma macropomum) to dietary cadmium (Cd) at concentrations of 0, 50, 100, 200, and 400 µg.g-1 dry food. Fish were sampled on days 15, 30, and 45 of the feeding trials. Tissues were collected for analysis of Cd concentration using graphite furnace atomic absorption spectrophotometry. Cd accumulation in the tissues occurred in the following order: kidney > liver > gills > muscle. Relative to other freshwater fish (e.g., rainbow trout, tilapia), tambaqui accumulated remarkably high levels of Cd in their tissues. Although Cd is known to affect Ca2+ homeostasis, no mortality or growth impairment occurred during feeding trials.
Agonistic and reproductive behaviors in males of red hybrid tilapia, Oreochromis niloticus (Linnaeus, 1758) x O. mossambicus (Peters, 1852) (Osteichthyes: Cichlidae)
Authors: Medeiros APT , Chellappa S , Yamamoto ME
Published: February 2008

The red hybrid tilapia, Oreochromis niloticus (Linnaeus, 1758) x O. mossambicus (Peters, 1852) is a fertile hybrid used in the semi-intensive level of fish culture in the Northeast of Brazil. It is a territorial cichlid and is highly aggressive towards conspecifics during the breeding season. The purpose of this study was to investigate and describe the aggressive behaviour displayed by the males of this hybrid in non-reproductive and reproductive contexts. Behavioural observations revealed that aggression displayed by the reproductive males of red hybrid tilapia included threatening, undulation, parallel, lateral and frontal attacks, chasing, escape and submission. Possession of a territory influenced male aggressiveness, which was more intense in their own territory than that observed in a neutral situation. The males built nests, irrespective of female presence. All the behavioural patterns were in accordance with those previously described for one parental species, the Nile tilapia, O. niloticus.
Pollination and breeding system of Couepia uiti (Mart. and Zucc.) Benth (Chrysobalanaceae) in the Pantanal da Nhecolândia
Authors: Paulino-Neto HF
Published: February 2008

The pollination biology and breeding system of Couepia uiti was studied. In this species, flowers opened at 06:00 AM anthesis, and nectar production began at around 0800 h, reached a maximum volume from 09:30 AM to 10:30 AM, and decreased thereafter. The nectar sugar concentration increased continuously, but showed an abrupt increase from 10:00 AM to 12:00 AM. Pollen release occurred at about 09:30 AM and was quickly collected. The stigmas became receptive at around 12:00 AM. The pollinators of C. uiti included the bees Apis mellifera, Xylocopa sp. and Bombus sp., and three species of wasps. This conclusion was based on the observation that these hymenopterans had C. uiti pollen on their bodies, visited the receptive flowers, and touched the anthers and stigmas, thereby promoting pollination. Of these floral visitors, A. mellifera was considered to be the most efficient pollinator. However, mixed pollination also occurred. The number of C. uiti flowers visited in the morning (n = 52) was three times smaller than in the afternoon (n = 62), and the species richness of floral visitors was also bigger in the afternoon (eight in the afternoon versus five in the morning). This finding indicated that these floral visitors preferred to exploit nectar rather than pollen. Controlled pollination experiments showed that C. uiti was a self-incompatible species that produced fruits only by cross-pollination. Treatments such as agamospermy and spontaneous and self-pollinations did not produce fruits.
Radular ultrastructure of South American Ampullariidae (Gastropoda: Prosobranchia)
Authors: Martín SM , Negrete LHL
Published: February 2008

The radula of five species of South American Ampullariidae was analysed by Scanning Electron Microscope (SEM) with the purpose of enlarging new studies on the systematic of this family. The studied species were Pomacea -canaliculata (Lamarck, 1822), Pomacea scalaris (d'Orbigny, 1835), Pomella (P.) megastoma (Gray, 1847), Asolene (A.) platae (Maton, 1809) and Felipponea neritiniformis (Dall, 1919). The central tooth shows different attributes which provide the means for generic determination; the analysis of the central tooth, the lateral and marginal ones by SEM adds further information for species differentiation.
Genetic diversity of two Brazilian populations of the Pampas deer (Ozotoceros bezoarticus, Linnaeus 1758)
Authors: Rodrigues FP. , Garcia JF. , Ramos PRR. , Bortolozzi J. , Duarte JMB.
Published: February 2008

The Pampas deer (Ozotoceros bezoarticus) is one of the most endangered Neotropical cervid with populations that have been drastically reduced to small and isolated ones, mainly because of its habitat destruction. Random amplified polymorphic DNA (RAPD) markers were used to analyze population divergence and genetic variation within and between two populations corresponding to distinct subspecies. The RAPD markers displayed substantial genetic variation with all animals possessing unique RAPD phenotypes over 105 polymorphic bands produced by 15 primers. An analysis of molecular variance (AMOVA) and a neighbor-joining cluster analysis were performed to assess levels of differentiation between populations. No differentiation was recorded and about 96.0% (P < 0.00001) of the total variance was attributable to variation within populations. This result is quite distinct from data obtained by the analysis of the mtDNA control region, and is discussed on the basis of genetic differences between the different markers and the male-biased dispersal patterns generally observed in the mammal species. The data presented herein are potentially useful for future taxonomic and genetic studies in this species, for the monitoring of the genetic variation observed within these populations, and for the development of management guidelines for its conservation.
Identifying management units in non-endangered species: the example of the sloth Bradypus variegatus Schinz, 1825
Authors: Moraes-Barros N. , Miyaki CY. , Morgante JS.
Published: February 2008

In this study we propose the analysis of genetic diversity of the common three-toed sloth, Bradypus variegatus, in an attempt to understand population structure, identify divergent intraspecific units, and contribute to the knowledge of biodiversity in the neotropical forests. We analyzed a 387 bp segment of the mitochondrial DNA control region in 28 individuals distributed in different localities of both Atlantic and Amazon forests. Our results demonstrated that the genetic diversity of B. variegatus is distributed in six management units, MUs. The observed MUs encompass six phylogenetic lineages and represent respectively north and south regions of Atlantic forest, three regions within the Amazon forest, and a transition region between these two biomes. Considering the fact that these MUs are concordant with phylogroups and endemism areas already described for other vertebrate species, we can say that the study of B. variegatus, a widely distributed and not endangered species, can help to identify areas for conservation biology purposes in neotropical rain forests.
Genetic diversity and evidence of recent demographic expansion in waterbird populations from the Brazilian Pantanal
Authors: Lopes IF. , Miño CI. , Del Lama SN.
Published: February 2008

The present study determined nuclear and mitochondrial (mtDNA) levels of genetic variability and phylogeographic patterns in breeding populations of Roseate Spoonbill (N = 57), Wood Stork (N = 89), and Jabiru Stork (N = 30), sampled in the Brazilian Pantanal. These species were selected since they are bioindicators of wetlands’ health and are threatened in other parts of their distribution. As they are in close association with this ecosystem, they are appropriate for studying the effects of Pleistocene climatic changes on their demographic patterns. Levels of nuclear genetic diversity in Pantanal populations were not significantly different from those of other populations throughout the American continent, where they are considered threatened or of special concern. Reduced levels of mtDNA genetic diversity were observed in the Central American population of Jabiru Stork in comparison to the Pantanal population. Recent demographic expansion in the Pantanal was markedly evidenced by unimodal patterns of mismatch distribution and Fu’s Fs neutrality test in these three species. We hypothesize that the average time of population expansion (between 30,843 and 14,233 years before present) is associated to responses of these birds’ populations to paleoclimatic changes in these wetlands during the last glaciation period. We recommend special conservation efforts with the Jabiru Stork populations, a genetic monitoring program based on mtDNA, and an ecological characterization of these waterbirds species throughout their distribution range.
Evolutionary cytogenetics of the Hoplias lacerdae, Miranda Ribeiro, 1908 group: a particular pathway concerning the other Erythrinidae fish
Authors: Morelli S. , Vicari MR. , Bertollo LAC.
Published: February 2008

The taxonomy/systematics of the Erythrinidae fish is still imprecise, with several doubts on their relationships. Karyotypes and chromosomal characteristics of some species of the Hoplias lacerdae group (Erythrinidae), from different Brazilian hydrographic basins and pisciculture stations, were analyzed in the present study, using conventional Giemsa staining, C-banding, silver staining, Mithramycin and Distamycin/DAPI fluorochromes, and fluorescent in situ hybridization (FISH). A diploid chromosome number of 2n = 50 and karyotypes composed of meta- and submetacentric chromosomes without sex-related differences were found. Only one active NOR (Nucleolar Organizer Region) site was found, which was identified by silver staining (Ag-NOR) and FISH, located on the chromosome pair 11, although additional 45S rDNA sites were also mapped on other chromosome pairs only by FISH. The Ag-NOR of the chromosome pair 11 was found to be GC-rich, appearing positive after Mithramycin staining. Mithramycin-positive/DAPI-negative sites were also observed in the centromeric/pericentomeric regions of the chromosome pairs 4, 6, 15, and 19, which have also affinity to silver nitrate. However, these four sites were not detected by FISH with the rDNA probe, indicating to be only argentophilic GC-rich heterochromatic regions. Chromosome data show that the karyotype evolution in Hoplias lacerdae group is relatively conserved and follows a particular pathway concerning the other Erythrinidae fishes, such as Hoplias malabaricus, Hoplerythrinus unitaeniatus, and Erythrinus erythrinus, in which polytypic karyotypes are found. Thus, the H. lacerdae group shows chromosome features that are not closely related to those of the congeneric H. malabaricus group. These finds, together with genetic and morphologic data, are important tools to be considered in a major revision of the Erythrinidae family, as well as for conservation programs.
Genetic diversity of three ornamental reef fishes (Families Pomacanthidae and Chaetodontidae) from the Brazilian coast
Authors: Affonso PRAM. , Galetti Jr. PM.
Published: February 2008

Reef fishes of the families Pomacanthidae (angelfish) and Chaetodontidae (butterflyfish) are popular ornamental species, intensively harvested for the aquarium trade. The impacts of such activity on intra-specific diversity and reef ecosystems are still poorly understood in the south Atlantic. In the present work, a fine-scale genetic analysis using RAPD markers was performed in distinct samples of the queen angelfish (Holacanthus ciliaris), French angelfish (Pomacanthus paru), and banded butterflyfish (Chaetodon striatus) along the Brazilian coast. Most of the genetic variation in the three species was related to intra-population diversity. However, AMOVA results demonstrated that H. ciliaris presents a subtle population structure (sigmast = 0.132, P = 0.003), while P. paru and C. striatus present low genetic differentiation, especially remarkable in the latter (sigmast = 0.090, P = 0.001 and sigmast = 0.041, P = 0.028, respectively). Gene flow (Nm) was also higher in C. striatus than in the angelfish species. The reported patterns of genetic differentiation contrast with the similar pelagic stage of the selected species, suggesting that larval dispersal per se is a poor predictor of population structure in these reef fishes. Ecological features coupled with biogeographic history and distinct local selective pressures might play a major role on the genetic composition of each species. Although preliminary, the present results provide a baseline for monitoring the genetic variability in these reef species. These differences in the genetic structure among co-occurring species should be taken into consideration for the conservation of eventual evolutionary units along the Brazilian Province.
Avaliação do conhecimento sobre o uso de inaladores dosimetrados entre profissionais de saúde de um hospital pediátrico
Authors: Muchão Fábio Pereira , Perín Sílvia La Regina Rodrigues , Rodrigues Joaquim Carlos , Leone Cláudio , Silva Filho Luiz Vicente Ribeiro Ferreira
Published: February 2008

OBJETIVO: Avaliar os conhecimentos sobre o uso e manejo de inaladores pressurizados dosimetrados entre profissionais de um hospital pediátrico terciário. MÉTODOS: Foram realizadas avaliações sobre o conhecimento do uso de inaladores pressurizados dosimetrados através de questionários teóricos e práticos, com médicos, fisioterapeutas, enfermeiras e auxiliares de enfermagem, atribuindo-se uma nota de 0 a 10 para cada avaliação. Calcularam-se as medianas das notas obtidas pelos profissionais de cada categoria, as questões com maiores e menores índices de erros, e foi feita a comparação descritiva do desempenho das diversas categorias profissionais. A análise estatística foi feita através do método de Kruskal-Wallis de comparação de medianas. Também foi realizada a análise através de regressão logística múltipla seqüencial. RESULTADOS: Foram avaliados 30 médicos residentes ou estagiários de pediatria, 23 médicos assistentes, 29 fisioterapeutas, 33 enfermeiras e 31 auxiliares de enfermagem. Os médicos residentes, fisioterapeutas e médicos assistentes obtiveram desempenho significativamente superior aos dos enfermeiros e auxiliares de enfermagem. Apenas os médicos residentes obtiveram mediana superior a 6. CONCLUSÕES: O conhecimento a respeito do uso de inaladores dosimetrados entre os profissionais de saúde da instituição é insatisfatório, principalmente entre enfermeiros e auxiliares de enfermagem, diretamente envolvidos na aplicação prática dos inaladores dosimetrados.
Impact of Yield Stress and Fracture-Face Damage on Production Using a Three-Phase, 2D Model
Authors: Barati R. , Hutchins R. D. , Friedel T. , Ayoub J. A. , Dessinges M. , England K. W.
Published: February 2008

The fracture propagation process using polymer-based fracturing fluids is commonly applied to increase the productivity of producing wells, especially in tight gas formations. During the fracturing operation a layer of concentrated polymer (filter cake) forms on the fracture faces, which limits the loss of fluid to the formation. However, during the production phase, the partially broken filter cake and remaining residues damage the fracture conductivity. The fracture cleanup process is complex and may suffer from the presence of a yield stress, non-Newtonian fluid in place, non-Darcy flow effects in both the fracture and matrix, crushed proppant, embedded proppant and formation spalling as well as both mechanical and hydraulic damage to the matrix near the fracture face. A previously published fast and robust single well model was applied to study the important parameters involved during the fracture cleanup process. This 3-phase, 2-D model is capable of modeling multiple parameters separately. However, the simulator code which was employed did not address the modeling of non-Darcy flow or the rock stress effects on permeability, but focused on the yield stress effects of the fracturing fluid. The simulator proved very useful for assessing the significance of reservoir capillary pressure, fracturing fluid viscosity and yield stress, formation damage, and fracture conductivity on low permeability gas reservoir production with permeabilities from 0.005 to 5 mD. These trends may not carry over to nanodarcy reservoirs, such as the gas shales. The three phases included gas, water and fracturing fluid.
Oil Rock Interaction: Impact on Optimum Drawdown
Authors: Harouaka A. , Arshad A. , Ahmed S. J. , Al-Majed A. A.
Published: February 2008

Oil rock interaction may lead some wells to a sharp decline in productivity which is not associated with a major drop in reservoir pressure or increase in water cut. Also excessive drawdown is known to cause productivity decline and potentially causes permanent damage to the wells through one or all of the following: Fine migration, asphaltene deposition and/or emulsion formation around the wellbore.

Flooding tests were performed under reservoir conditions of pressure and temperature using filtered reservoir crude oil and synthetic brine generated from a geochemical analysis representative of the reservoir brine.

A major finding of the experimental displacement tests showed that monitoring of pressure gradient across the cores at various flow rates and water cuts have indicated a marked rock fluid interaction rendering Darcy's law inapplicable. Emulsion formation has been monitored through visual observation first using a sight glass ahead of the backpressure regulator followed by observation under ambient conditions.

The nature and distribution of fines inside the cores as well as hydrocarbons deposition were evaluated through post-flood examination of the cores under the microscope as well as by SEM and thin section techniques, and comparison with pre-flood conditions.

The main objective of this paper is to describe the adopted approach, utilizing field data and laboratory experiments to quantify the impact of rock fluid interaction on optimum drawdown.
Case Study: Analysis of the Characteristics of the Damage to Dujiatai Low-Permeability Reservoir by Water Injection and Research of Damage Removal Methods
Authors: Zhengchao Zhao , Wei Liu
Published: February 2008

Dujiatai reservoir has an oil bearing area of 37.2km2 with the OIP of 2409×104t, burial depth of −2650∼-2960m, porosity of 15.1% and permeability of 37.7×10−3µm−2. In general, the reservoir is produced initially under natural energy by elastic drive and solution gas drive and development with water injection is tested in the later stage due to fast pressure decline and subsequent substantial production decline.

During the water injection field test, although the water to be injected had been filtered to a fine degree, the water injection pressure increased substantially after a short time and water injection became difficult and some of the injectors were forced to be shut in because no water could be injected.

The paper introduces the analysis results of the tests on water injection damage to Dujiatai low permeability reservoir. (1) Solid particles entered the reservoir, forming blockage due to the small throats of filtration with the average radius of the throats of about 1.0μm; (2) Because the injected water was not treated against swelling, clay swelled, forming blockage due to the medium to strong water sensitivity of the reservoir; (3) Because of the medium to strong velocity sensitivity of the reservoir, fine particles staying in a unconsolidated manner on the borehole walls or inner surface of the base rocks fell out, migrated and piled up at the throats, forming blockage; (4) The scaling tendency of CaCO3 of the injected water was obvious and the scales adhered to the inner surface of the throats, reducing the filtration radius of the throats; (5) The water injection pipeline was corroded seriously and the suspended particle content at the outlet of the filtering station reached the standard, but it exceeded the standard after going through the water injection pipeline and reaching the wellhead and it was even worse when it reached the bottom of the well.

The solutions for the water injection damage to Dujiatai low permeability reservoir are as follows. (1) Acidization or acid fracturing deeper into the formations with weak acids is conducted to erode the unstable migrating particles; (2) Antiswelling agent is added to the injecting water to reduce clay swelling; (3) A secondary filtering unit is set up at the wellhead or the water injection pipeline is replaced with a corrosion prevention pipeline lined with fiberglass.
Through-pump Stimulation: A Cost Effective Alternative
Authors: Ojukwu K. I.
Published: February 2008

Electrical submersible Pumps (ESPs) have been employed for decades in accelerating oil production and creating pressure head needed to produce sub hydrostatic wells. ESPs are installed downhole and comprise stages of impellers driven by electrical motors that are automatically cooled by the passing fluid.

A major disadvantage of ESPs is blocking access to well re-entry for surveillance and through-tubing intervention. One of such cases is during acid stimulation. In Petroleum Development Oman (PDO), acid jobs have been carried out as part of workovers to retrieve the pumps first. The cost implication can be tremendous ranging from $250,000 to $400,000.

Two deployment techniques were adopted in PDO recently by bullheading acid through ESP and Coiled Tubing (CT) into the reservoir and by so doing, saved 80-93% of comparative cost. The techniques involved the use of abrasive resistant ESP for vertical wells and ESP bypass (Y-Tool) for CT deployment in horizontal wells. The challenges of using these techniques include damaging the ESP with acid or mistakenly circulating acid via the tubing-casing annulus. We have been able to apply these techniques successfully in acidizing a sub hydrostatic carbonate reservoir. In one example, new vertical well was stimulated to enhance matrix withdrawal from 20m3/d (120bbl/d) to 128/d (790bbl/d) dry oil and in another example, a new horizontal well which was severely damaged by high viscous pill was stimulated via CT. These have opened new opportunity for matrix well withdrawal in this reservoir.

This paper presents examples of candidate selection, cost justification, pump selection and acid recipe. It also illustrates the innovative deployment techniques used to prevent pump & tubular damage as well as achieving proper acid placement into the reservoir. These examples can be treated as best practice worth replicating in all ESP applications worldwide.
Benefits of a p-3D Over a 2D Model for Unified Fracture Design
Authors: Economides Michael J. , Demarchos Andronikos
Published: February 2008

Almost all commercial hydraulic fracture models are simulators that use injection variables such as fluids and proppants to predict fracture geometry. Totally different in both philosophy and approach are fracture design models which are aimed to first determine the optimum fracture geometry to maximize production (or injection) and then to establish the best way to achieve the desired geometry.

Starting with a treatment schedule, and with fracture mechanics, fluid mechanics and rock mechanics modeling of varying degrees of sophistication, fracture simulators predict the fracture geometry. While these models were originally using the classic 2D models they have evolved into pseudo-three-dimensional (p-3D) and, even, in some cases, fully three-dimensional (3D) models.

The same models are used to match the observed pressure in the field and because usually the original intent was to match net fracturing pressure they have incorporated among other things, near-wellbore tortuosity and tip-propagation effects, adding further dimensions of complexity. At the same time they provide facility to adjust their predictions with actual pressure measurements. Whether this multi-adjustment capability leads to better understanding of phenomena is another matter.

The most serious deficiency of most industry models is that they do not provide for optimum fracture performance from a production engineering point of view. They try many "proppant schedules" until one appears the "best". Clearly such ad hoc approach is flawed and statements such as "maximizing conductivity" still torment the industry.

We have a different approach. We use the Unified Fracture Design (UFD) theory to pinpoint the optimum fracture dimensions and then use our p-3D model to allow for the necessary injection. The main benefit of our p-3D approach is to account for constraints, real reservoir configurations and heterogeneity. The use of p-3D models in a design-driven fracture simulation is recommended with the resulting fracture geometry satisfying all elements that other p-3D models can do but, far more important, the geometry thus derived is exactly the one that can maximize well productivity.
Wettability Alteration at Elevated Temperatures: The Consequenses of Asphaltene Precipitation
Authors: Escrochi M. , Nabipour M. , Ayatollahi Sh. , Mehranbod N.
Published: February 2008

Asphaltenes are undoubtedly one of the important difficulties in the oil industry; its precipitation can impose specific affects on the productivity of the producing zone, as well as in the surface facilities and transportation lines. The main in situ consequences are their effect on the permeability by pore blockade, and on the wettability alteration by surface precipitation. In this paper, thermally induced wettability alteration is studied experimentally. The changes in the rock mineral content after imposing heat as the effect of thermal oil recovery are also studied using XRD. The results verify that asphaltene precipitation could be considered as the main platform for wettability reversal and the permeability reduction in the treated zone. The results also clarify the contradictory doubts around wettability alteration during thermal treatment in the literature. The experimental data shows that the media is gradually altered to strongly oil-wet in the temperature range of 150 – 400°C and subsequently changed to water-wet as the temperature increased.

Furthermore, the effects of temperature on asphaltene destabilization and precipitation is studied and the required thermodynamic criterion for asphaltene precipitation is found. The asphaltene precipitation in the formation by the thermal oil recovery techniques is thermodynamically modeled using regular solution theory.

The simulated date obtained using the model verifies by the experimental results. The model shows that as formation temperature increases toward crude oil's bubble point, its molar volume increases and solubility of the asphaltene decrease. This leads to asphaltene precipitation, and alteration of wettability toward strongly oil-wet condition. At temperatures higher than the crude oil bubble point, precipitated asphaltene start to dissolve, mainly due to evaporation of crude oil saturates. This stimulates a wettability shift toward more water-wet condition.
Mechanisms, Parameters, and Modeling of Naphthenate Soap-Induced Formation Damage
Authors: Sarac S. , Civan F.
Published: February 2008

The naphthenate soap deposition and related formation damage in petroleum reservoirs are investigated by means of the laboratory-scale experimental and theoretical studies. Experiments were carried out in three directions to understand and quantify the naphthenate soap deposition problem. Static bottle tests were conducted to determine the precipitation rate for various pH and temperature conditions. Microscopy investigations were carried out to verify the growth of naphthenate soap particles under different pH conditions. Core flow tests were conducted to generate naphthenate soap particles and to determine the permeability impairment caused by subsequent deposition of these particles in porous media under flowing conditions and different pH values. A power-law expression was proposed and verified for the precipitation rate of the naphthenate soap particles. The parameters of the rate equation were correlated with respect to pH and temperature. This also allowed the determination of the critical pH value for the onset of naphthenate soap precipitation. The results of the particle size experiments were described by a particle growth equation and the parameters of the equation were correlated with respect to pH. The core flow experiments proved the occurrence of formation damage caused by naphthenate soap precipitation and subsequent deposition. The permeability impairment in core flow experiments was described by a new differential model. The applications presented in this study provide insights for understanding of the mechanism and magnitude of naphthenate soap-induced formation damage, and help in taking proper measures for avoiding the formation damage caused by naphthenate soap deposition.
Potential Damage Due to Relative Permeability Modifiers: Laboratory Studies and A Case History
Authors: Al-Taq Ali A. , Nasr-El-Din Hisham A. , Saudi Mohammed M. , Sierra Leopoldo
Published: February 2008

Relative permeability modifiers (RPM), hydrophobic in nature, are used to selectively reduce permeability to water with minimum impact on permeability to oil. Lab studies and field application reveal that RPM polymers, in some conditions, may damage the permeability to oil resulting in reduction/ or lost of oil production.

Single and parallel core flow tests were conducted on carbonate and sandstone cores at reservoir conditions. Single core flow tests showed that RPM polymers can damage tight cores (less than 1 md) by forming an external filter cake on the injection face of the cores. Accumulation of RPM polymers at the face of the core means that these chemical will not properly propagate inside the core, which significantly reduces their ability to minimize water production.

Parallel core-flood experiments conducted at reservoir temperature (200°F) showed that RPM damaged the permeability to oil when there was a large permeability contrast (greater than 1:5) in favor of the oil-saturated core. Due to the high permeability contrast, most of RPM polymer solution preferentially entered the oil-saturated zone, thus damaged the oil production zone. Field data supported lab findings and showed that oil production of an oil well dropped significantly following RPM polymer treatment. It was found that polymer injection rate was a key factor to minimize damage to the oil-saturated core whenever we have a large permeability contrast in the favor of oil-saturated core. Injection of RPM polymer at low rate (1 cm3/min) was found to minimize damage to the oil-saturated core.

Field results showed that application of water control treatment using RPM polymer on an oil well resulted in a significant loss in oil production. Post treatment analysis indicated that RPM polymer solution entered mainly the oil-saturated zone, which was attributed to the large permeability contrast in favor of the oil-saturated zone. This paper will present detailed lab studies and field data obtained and will recommend the proper RPM polymer application method to avoid damaging oil producing zones.
Controlling Proppant Flowback to Maintain Fracture Conductivity and Minimize Workovers: Lessons Learned from 1,500 Fracturing Treatments
Authors: Trela Jim M. , Nguyen Philip D. , Smith Billy R.
Published: February 2008

The use of curable resin precoated proppants was often applied in the Permian Basin to control proppant flowback. However, these precoated proppant materials continued to allow proppant to produce back, especially during production surges because they did not provide sufficient consolidation strength to handle high drawdown. Since early 2005, a low-temperature curable liquid resin system has been selected to treat the proppant on-the-fly mainly during the tail-in stages in most of 1,500 hydraulic fracturing treatments. This paper highlights how the proppant back-production problems were successfully overcome through the application of this curable resin system. Detailed descriptions of the treatments, challenges, and lessons learned during the course of these fracturing treatments are presented.

Evaluation of these treatments has revealed that an optimum concentration of resin coating maximizes bonding between proppant grains and the consolidation strength of the coated proppant pack, locking the grains in place while minimizing any reduction of conductivity. Field results indicate that application of on-the-fly resin coating treatments effectively stops proppant flowback while allowing production rates to be maintained as designed. These treatments have drastically decreased the number of workovers for treated wells compared to those treated with resin precoated proppant or without resin treatments. This resin treatment process provides an economical means for controlling proppant flowback in wells with marginal reserves.