bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology of the male gonads of the spiny lobster Panulirus laevicauda (Latreille, 1817)
Authors: Lima Ana Valêsca Pinto de , Gesteira Tereza Cristina Vasconcelos
Published: September 2008

The present study represented a contribution to the knowledge of the cytological and histological aspects of decapods' reproductive system, describing male germ cells of the spiny lobster Panulirus laevicauda. Seventy-one specimens of different sizes were caught off Fortaleza (Ceará, Brazil). Their testes were removed and fixed in Bouin solution, then, after 24 hours, dehydrated, cleared and embedded in the paraffin. Sections (4 µm thick) were stained with hematoxylin-eosin. The testes appeared macroscopically as a pair of long and highly convoluted tubes joined by a transversal commissure giving the organ an H-like shape. Microscopically, supporting cells and germ cells (spermatogonia I and II, spermatocytes, spermatids and spermatozoa) were seen in the testicular acini. Some of the acini showed signs of the spermotocytes and the spermatogonia degeneration. The spermatozoa were small cells with the peripheral nuclei and a lightly basophilic cytoplasm. They were nonmotile gametes and are characterized by the absence of a flagellum, but they had spikes radiating from the body. Three stages of follicular development in the mature individuals were observed: (a) predominance of spermatogonia I and II; (b) increasing numbers of spermatocytes I and II; and (c) spermatocytes I and II were prevalent. All the three stages of the spermatozoa were observed in the follicular lumen. These observations agreed with the published descriptions of other palinurid and homarid lobsters. A histochemical analysis of the testes showed that the main component of the tunic was collagenous fibers, that the seminal fluid contained plenty of glycoproteins and carboxyl-glycoconjugates and that the spherical bodies and spermatozoa contained glycoproteins and mucoproteins.
Spray-dried tomato powder: reconstitution properties and colour
Authors: Sousa Alexandre Santos de , Borges Soraia Vilela , Magalhães Natália Ferreira , Ricardo Hevandro Vaz , Azevedo Aline Damico
Published: September 2008

Powdered tomato was produced by spray drying the tomato pulp. A full 2³ factorial design with the central point was used, varying the feed flow rate (127-276 g/min), air inlet temperature (200-220ºC) and the atomisation speed (25,000-35,000 rpm). The responses analysed were: moisture content, solubility, wettability consistency and colour, but the factors only significantly affected the colour parameter. All the samples became significantly darker and less red with an increase of the variables under study. A low atomisation speed (25,000 rpm) and lower inlet air temperature (220ºC) produced the powders with a higher colour index (a/b) and less darkening.
Baudelaire au miroir de Malraux
Authors: Khémiri Moncef
Published: September 2008

Cet essai a pour but de comparer la pensée esthétique de Baudelaire et celle de Malraux, à partir de l'étude inaugurale de Claude Pichois sur la place importante qu'occupe l'auteur des Fleurs du mal et des Curiosités esthétiques dans la réfl exion d'André Malraux. Mais non seulement: il ajoute aux sources déjà connues la correspondance de Malraux, sa "bibliothèque esthétique" et les dossiers de genèse de La Métamorphose des dieux que l'auteur de cet article a eu l'occasion de consulter pour l'édition des Ecrits sur l'art d'André Malraux en Pléiade.
Influência da taxa de resfriamento na corrosão em aço inoxidável fundido
Authors: Mariano N.A. , Murolo J.P. , Pereira V.F. , Pallone A.S.N. , Tommaselli M.A.G.
Published: September 2008

As indústrias de extração de petróleo e produção de gás têm utilizado de forma crescente os aços inoxidáveis, por serem ligas que combinam boa propriedade mecânica a resistência à corrosão e são economicamente viáveis, para aplicações em linha de escoamento onshore e offshore. Estes materiais geralmente exibem excelente resistência à corrosão, tenacidade e soldabilidade. Entretanto, de todos os tipos de corrosão, a corrosão de localizada por pite é o processo mais difícil de controlar. O presente trabalho estuda o efeito da taxa de resfriamento na corrosão dos aços inoxidáveis martensíticos 13Cr-4Ni-0,02C e 13Cr-2Ni-0,1C. Foi observado que o aumento da taxa de resfriamento levou a formação de uma microestrutura refinada e com estruturas dendríticas. A taxa de corrosão foi determinada por ensaio de imersão e foi observado que quanto maior a taxa de resfriamento, maior a taxa de corrosão para os aços estudados. A densidade de pite, profundidade de pite e taxa de corrosão foram maiores para o aço 13Cr-2Ni-0,1C. Isto se deve por apresentar uma microestrutura mais refinada e maior quantidade de estruturas dendríticas, que podem atuar como sítios nucleantes no processo de corrosão.
Fenómenos de relajación interfacial en compuestos epoxi/aluminio
Authors: Ramajo L. , Castro M.S. , Reboredo M.M.
Published: September 2008

En este trabajo se estudiaron los fenómenos de relajación de materiales compuestos polímero/metal en función de la cantidad de partículas de metálicas incorporadas (aluminio). El concepto de módulo eléctrico fue empleado para analizar los procesos de relajación tipo Debye y Maxwell-Wagner-Sillar, debido a que presenta varias ventajas con respecto al análisis clásico de la parte real (ε') e imaginaria (ε") de la permitividad. El material compuesto se obtuvo por colada y posterior curado a 100ºC por 2 horas, previa mezcla en un mezclador ultrasónico de ambos componentes. La densidad de las muestras se determinó por el método de Arquímedes, mientras que las fracciones en volumen se establecieron mediante termogravimetría. Las mediciones de propiedades dieléctricas se realizaron en el rango de frecuencias de 25Hz a 1Mhz y temperatura de 30 a 120ºC. Por último, la microestructura fue observada mediante Microscopía Electrónica de Barrido. Las micrografías revelaron que la incorporación del metal no incrementó en forma significativa la cantidad de defectos o la porosidad. Los resultados del análisis dieléctrico mostraron que los materiales poseen muy buenas propiedades dieléctricas a bajas temperaturas, y que los fenómenos de relajación son propios de la resina y modificados por la influencia de las cargas metálicas debido a fenómenos de relajación interfacial tipo MWS.
Influência da forma de indução à acidose na determinação da intensidade de lactato mínimo em corredores de longa distância
Authors: Santhiago Vanessa , Silva Adelino Sanchez Ramos da , Guglielmo Luiz Guilherme Antonacci , Higino Wonder Passoni
Published: September 2008

O objetivo principal deste estudo foi verificar se diferentes formas de indução à acidose interferem na determinação da intensidade do lactato mínimo (LACmin) em corredores de longa distância. Desse modo, 14 corredores de provas fundas do atletismo participaram do estudo. Os atletas realizaram três protocolos: 1) teste incremental em esteira rolante, com incrementos de 1km.h-1 a cada três minutos até a exaustão, para a determinação das intensidades de limiar anaeróbio (OBLA), de limiar aeróbio (Laer), consumo máximo de oxigênio (VO2max) e intensidade de consumo máximo de oxigênio (vVO2max); 2) teste de lactato mínimo em pista de atletismo (LACminp), que consistiu de dois esforços máximos de 233m na pista de atletismo com intervalo de um minuto entre cada repetição, com oito minutos de recuperação passiva, seguido de um teste incremental semelhante ao do protocolo 1; e 3) teste de lactato mínimo em esteira rolante (LACmine), constituído de dois esforços máximos de um minuto e 45 segundos com intervalo de um minuto, na intensidade de 120% da vVO2max, seguido dos mesmos procedimentos do protocolo 2. Foram coletadas amostras de sangue do lóbulo da orelha ao final de cada estágio em todos os protocolos e no 7º minuto de recuperação passiva dos testes de LACmine e LACminp. A análise de variância (ANOVA) mostrou que ocorreram diferenças significativas entre as intensidades de LACmine (13,23 ± 1,78km.h-1) e OBLA (14,67 ± 1,44km.h-1). Dessa maneira, a partir dos resultados obtidos no presente estudo, é possível concluir que a determinação da intensidade correspondente ao lactato mínimo é dependente do protocolo utilizado para a indução à acidose. Além disso, o LACmine subestimou a intensidade correspondente ao OBLA, não podendo ser utilizado para a mensuração da capacidade aeróbia de corredores fundistas.
Análise empírica de modelos de valuation no ambiente brasileiro: fluxo de caixa descontado versus modelo de Ohlson (RIV)
Authors: Galdi Fernando Caio , Teixeira Aridelmo José Campanharo , Lopes Alexsandro Broedel
Published: September 2008

Dentro do contexto controverso de comparações entre modelos de valuation, o presente trabalho investiga, baseado nas projeções dos analistas de mercado de capitais para empresas brasileiras, se existem diferenças entre os valores de uma empresa estimados pelo modelo de fluxo de caixa descontado (DCF) e pelo modelo de Ohlson (modelo de lucros residuais - RIV). Essa abordagem é inovadora à medida que trabalhos já realizados visando à comparação entre esses modelos consideram o valor da empresa calculado com base nas informações publicadas/divulgadas pela empresa e não com base na expectativa dos agentes de mercado (como por exemplo, o analista de mercado de capitais). Entretanto, a correta implementação dos modelos em análise deve ser realizada considerando-se as expectativas dos agentes de mercado. Adicionalmente, são realizadas regressões para verificar qual dos modelos (DCF ou OHLSON) explica melhor a relação preço/valor patrimonial (P/B) de uma empresa em períodos futuros. As conclusões obtidas foram: i) existem diferenças estatisticamente significantes para o valor estimado das empresas pelo fluxo de caixa descontado e pelo modelo de Ohlson (RIV) e ii) os índices P/B, calculados a partir das estimativas dos analistas (que utilizam o DCF), apresentam maior poder explicativo dos índices P/B futuros da empresa do que as estimativas do índice P/B feitas pelo modelo de Ohlson (RIV).
Câncer de pulmão: histologia, estádio, tratamento e sobrevida
Authors: Novaes Fabiola Trocoli , Cataneo Daniele Cristina , Ruiz Junior Raul Lopes , Defaveri Júlio , Michelin Odair Carlito , Cataneo Antonio José Maria
Published: September 2008

OBJETIVO: Analisar os principais tipos histológicos, estádio, tratamento e sobrevida dos portadores de câncer de pulmão. MÉTODOS: Estudo retrospectivo a partir da análise dos prontuários de pacientes acompanhados no Hospital das Clínicas da Faculdade de Medicina de Botucatu, num período de seis anos. RESULTADOS: De janeiro de 2000 a janeiro de 2006, foram acompanhados 240 doentes com câncer de pulmão, com predominância do sexo masculino (64%). O tipo histológico mais freqüente foi o carcinoma escamoso (37,5%), seguido pelo adenocarcinoma (30%), carcinoma neuroendócrino (19,6%) e carcinoma de grandes células (6,6%). Apenas 131 pacientes (54,6%) foram tratados. Destes, 52 pacientes (39,7%) foram submetidos à quimioterapia exclusiva, 32 (24,4%) realizaram quimioterapia associada à radioterapia e 47 (35,9%) foram submetidos à cirurgia associada ou não à quimioterapia exclusiva e/ou radioterapia. Somente 27 pacientes (20,6%) foram submetidos à cirurgia exclusiva.Em relação ao estadiamento, 34,4% apresentavam, no momento do diagnóstico, estádio IV, 20,6% estádio IIIB, 16,8% estádio IIIA e os outros 28,2% pertenciam aos estádios I e II. A sobrevida em cinco anos foi de 65% para o estádio I e 25% para os estádios remanescentes. CONCLUSÕES: O tipo histológico predominante foi o carcinoma escamoso e o de menor freqüência foi o carcinoma de grandes células. A maioria se encontrava em estádio avançado ao diagnóstico, estando nos estádios iniciais menos de 30% dos casos. Isto justifica a baixa sobrevida e a pequena quantidade de pacientes submetidos ao tratamento cirúrgico exclusivo, em comparação à maioria que foi submetida à quimioterapia exclusiva.
Mortalidade específica por tuberculose no estado do Espírito Santo, no período de 1985 a 2004
Authors: Moreira Cláudia Maria Marques , Zandonade Eliana , Reynaldo Dietze , Maciel Ethel Leonor Noia
Published: September 2008

OBJETIVO: O objetivo deste trabalho é descrever a mortalidade específica por tuberculose no estado do Espírito Santo, e sua tendência em relação às variáveis: forma clínica, sexo e faixas etárias. MÉTODOS: Realizou-se um estudo descritivo retrospectivo baseado em dados secundários. Foram incluídos os óbitos registrados no Sistema de Informações sobre Mortalidade que possuíam como causa básica a tuberculose de residentes no estado do Espírito Santo, no período de 1985 a 2004. RESULTADOS: A taxa de mortalidade específica ajustada por tuberculose de todas as formas acompanhou a taxa de mortalidade geral do estado apresentando redução de 5,6/100.000 habitantes, em 1985, para 2,0/100.000 habitantes, em 2004. A forma pulmonar foi a mais freqüente em todo o período (89,7% dos óbitos por tuberculose). A razão da taxa de mortalidade no sexo masculino/feminino variou de 1,1 em 1998 a 3,19 no ano de 2004. CONCLUSÕES: Ocorreu redução da taxa de mortalidade em todas as faixas etárias. A predominância da forma pulmonar, sexo masculino e faixas etárias mais avançadas foram semelhantes à da mortalidade específica por tuberculose no país como um todo.
Pharmacokinetics of Oral Posaconazole in Neutropenic Patients Receiving Chemotherapy for Acute Myelogenous Leukemia or Myelodysplastic Syndrome
Authors: Krishna Gopal , AbuTarif Malaz , Xuan Fengjuan , Martinho Monika , Angulo David , Cornely Oliver A.
Published: September 2008

Study Objective. To analyze the pharmacokinetics of posaconazole administered as prophylaxis for invasive fungal infection (IFI) in neutropenic patients receiving chemotherapy for acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS).

Design. Pharmacokinetic subanalysis of a phase III, prospective, randomized, multicenter, evaluator‐blinded trial comparing posaconazole with standard azoles (fluconazole and itraconazole).

Patients. One hundred ninety‐four patients with AML or MDS who received posaconazole oral suspension 200 mg 3 times/day with meals or a nutritional supplement for a minimum of 7 days to achieve steady state and for a maximum of 12 weeks.

Intervention. For the first 20 patients, blood samples were collected before the first dose on day 8 and at 2, 4, 6, and 24 hours after that first dose; for all other patients, blood samples were collected at 1 and 3 hours after the first dose on day 8 and during the first episode of evaluation for a possible IFI.

Measurements and Main Results. The effects of the following covariates on average (Cav) and maximum (Cmax) posaconazole plasma concentrations at steady state were explored: age, sex, and race‐ethnicity; proven or probable IFI; baseline body weight and body surface area; and baseline (on or before day 7) increases in liver enzyme levels, mucositis, neutropenia, diarrhea, vomiting, or use of an H2‐receptor antagonist or proton pump inhibitor. Diarrhea, proton pump inhibitor use, γ‐glutamyl transferase level of 2 or more times the upper limit of normal, and race‐ethnicity reduced Cav. Although statistically significant, these results were not considered clinically significant and did not necessitate posaconazole dosage adjustments. Mean Cav and Cmax values did not appear different in the six patients with IFIs (three with proven IFIs, three with probable IFIs) compared with the entire sample of 194 patients; however, a definitive conclusion cannot be made due to the small sample size of patients with IFI. No factor found to affect posaconazole concentrations predominated in patients with IFIs.

Conclusion. Oral posaconazole 200 mg 3 times/day provided plasma concentrations adequate for preventing IFIs. No dosage adjustments are recommended based on any covariate tested.
Paliperidone Extended‐Release for the Treatment of Schizophrenia
Authors: Marino Jehan , Caballero Joshua
Published: September 2008

Paliperidone, the major active metabolite of risperidone (9‐hydroxy‐risperidone), is a second‐generation antipsychotic that was recently approved by the United States Food and Drug Administration for treatment of acute schizophrenia and for maintenance treatment of schizophrenia. We performed a literature search of PreMEDLINE, MEDLINE, and International Pharmaceutical Abstracts from 1966‐October 2007 to review the available data on the pharmacology, pharmacokinetics, clinical evidence, and safety and tolerability profile of paliperidone extended‐release (ER). Articles from randomized controlled trials, abstracts, and posters presented at national scientific meetings were included in this review. Paliperidone ER has been shown to be significantly more effective in improving schizophrenic symptoms according to the Positive and Negative Symptom Scale (PANSS), Clinical Global Impressions‐Severity Scale, and Personal and Social Performance Scale compared with placebo (p<0.05). In addition, limited evidence suggests similar efficacy between paliperidone ER 6–12 mg/day and risperidone 4–6 mg/day. A 2‐week, double‐blind comparison with quetiapine demonstrated that paliperidone ER was significantly better than quetiapine in improving PANSS scores (p<0.001). Paliperidone ER appears to be well tolerated at the recommended starting dosage of 6 mg/day. The most commonly reported adverse effect was dose‐related extrapyramidal symptoms. Weight gain and metabolic disturbances were minimal. The cost of paliperidone ER appears to be slightly higher than that of other second‐generation antipsychotics. Paliperidone ER tablets may be a safe and effective treatment option for acute schizophrenia and maintenance treatment of schizophrenia compared with placebo. Because well‐designed comparative data are lacking, an additional benefit over other antipsychotics is yet to be determined.
INFLUENCES OF A CALCIUM GRADIENT ON SOIL INORGANIC NITROGEN IN THE ADIRONDACK MOUNTAINS, NEW YORK
Authors: Page Blair D. , Mitchell Myron J.
Published: September 2008

Studies of the long‐term impacts of acidic deposition in Europe and North America have prompted growing interest in understanding the dynamics linking the nitrogen (N) and calcium (Ca) cycles in forested watersheds. While it has been shown that increasing concentrations of nitrate (NO3−) through atmospheric deposition or through nitrification can increase Ca loss, the reciprocal effects of Ca on N transformation processes have received less attention. We studied the influence of soil Ca availability on extractable inorganic N (NO3− + NH4+) across a Ca gradient in the Adirondack Mountains, New York, USA. Our results did not show the direct Ca–N interaction that we had expected, but instead showed that exchangeable Ca coupled with soil moisture, soil organic matter, and ambient temperature accounted for 61% of the variability in extractable inorganic N across 11 sites over two growing seasons. Soil Ca concentrations were, however, positively related to sugar maple (Acer saccharum) and American basswood (Tilia americana) basal areas and negatively related to American beech (Fagus grandifolia) basal area. Based on litter chemistry differences among these tree species and reported potential N mineralization values, we suggest that the influence of Ca on soil inorganic N is through a multistep pathway: reciprocal interactions between soil Ca concentrations and species composition, which in turn affect the quality of litter available for N mineralization. If chronic soil Ca depletion continues, as reported in some forested ecosystems, potential shifts in biotic communities could result in considerable alterations of N cycling processes.
TROPICAL COASTAL HABITATS AS SURROGATES OF FISH COMMUNITY STRUCTURE, GRAZING, AND FISHERIES VALUE
Authors: Harborne Alastair R. , Mumby Peter J. , Kappel Carrie V. , Dahlgren Craig P. , Micheli Fiorenza , Holmes Katherine E. , Brumbaugh Daniel R.
Published: September 2008

Habitat maps are frequently invoked as surrogates of biodiversity to aid the design of networks of marine reserves. Maps are used to maximize habitat heterogeneity in reserves because this is likely to maximize the number of species protected. However, the technique's efficacy is limited by intra‐habitat variability in the species present and their abundances. Although communities are expected to vary among patches of the same habitat, this variability is poorly documented and rarely incorporated into reserve planning. To examine intra‐habitat variability in coral‐reef fishes, we generated a data set from eight tropical coastal habitats and six islands in the Bahamian archipelago using underwater visual censuses. Firstly, we provide further support for habitat heterogeneity as a surrogate of biodiversity as each predefined habitat type supported a distinct assemblage of fishes. Intra‐habitat variability in fish community structure at scales of hundreds of kilometers (among islands) was significant in at least 75% of the habitats studied, depending on whether presence/absence, density, or biomass data were used. Intra‐habitat variability was positively correlated with the mean number of species in that habitat when density and biomass data were used. Such relationships provide a proxy for the assessment of intra‐habitat variability when detailed quantitative data are scarce. Intra‐habitat variability was examined in more detail for one habitat (forereefs visually dominated by Montastraea corals). Variability in community structure among islands was driven by small, demersal families (e.g., territorial pomacentrid and labrid fishes). Finally, we examined the ecological and economic significance of intra‐habitat variability in fish assemblages on Montastraea reefs by identifying how this variability affects the composition and abundances of fishes in different functional groups, the key ecosystem process of parrotfish grazing, and the ecosystem service of value of commercially important finfish. There were significant differences in a range of functional groups and grazing, but not fisheries value. Variability at the scale of tens of kilometers (among reefs around an island) was less than that among islands. Caribbean marine reserves should be replicated at scales of hundreds of kilometers, particularly for species‐rich habitats, to capture important intra‐habitat variability in community structure, function, and an ecosystem process.
AN ECOHYDROLOGICAL ANALYSIS FOR OPTIMAL USE OF REDISTRIBUTED WATER AMONG VEGETATION PATCHES
Authors: Yu Mei , Gao Qiong , Epstein Howard E. , Zhang Xinshi
Published: September 2008

Ecosystem processes in semiarid landscape mosaics are strongly affected by the interactions among water utilization, plant growth, and vegetation patterns. Management of these semiarid landscapes can be improved with better understanding of the complex interactions between ecology and hydrology that determine the water‐use efficiency at landscape and regional scales. However, quantifying the effects of runoff and applying ecohydrological principles toward the improvement of land‐use management requires additional research to integrate the ecological and hydrological processes. This study highlights the importance of runoff in the management of vegetation to retard desertification by reducing soil erosion. By coupling a plant growth model with a simple GIS‐based model of water redistribution and use, we analyzed the interactions among runoff generation, “runon” reabsorption, and plant growth, in a small watershed in the semiarid sandy grassland area of northern China. Net primary productivity (NPP) and water utilization for the watershed were calculated for different managerial schemes. Annual aboveground NPP (NPPa), maximum leaf biomass (Mleafmax), and water use simulated with runoff effects were 18%, 21%, and 8% greater, respectively, than those simulated without runoff redistribution. Furthermore, simulation with a proposed management strategy for sandy grassland landscapes, which prescribes different plant functional types (grasses, shrubs, and trees) distributed at different slope positions, led to increasing NPPa, Mleafmax, and water use by 34%, 38%, and 28%, respectively, compared to the current land use. The increases in NPP and biomass in turn would reduce wind erosion and associated dust‐storm generation and enhance capacity of the system to retard degradation. The coupled model thus can be used as a tool to quantify effects of runoff redistribution for optimal land management and environmental protection, and the study has important managerial implications for semiarid systems, where degradation is of major concern, and runoff redistribution is important.
USING DEMOGRAPHY AND MOVEMENT BEHAVIOR TO PREDICT RANGE EXPANSION OF THE SOUTHERN SEA OTTER
Authors: Tinker M. Tim , Doak Daniel F. , Estes James A.
Published: September 2008

In addition to forecasting population growth, basic demographic data combined with movement data provide a means for predicting rates of range expansion. Quantitative models of range expansion have rarely been applied to large vertebrates, although such tools could be useful for restoration and management of many threatened but recovering populations. Using the southern sea otter (Enhydra lutris nereis) as a case study, we utilized integro‐difference equations in combination with a stage‐structured projection matrix that incorporated spatial variation in dispersal and demography to make forecasts of population recovery and range recolonization. In addition to these basic predictions, we emphasize how to make these modeling predictions useful in a management context through the inclusion of parameter uncertainty and sensitivity analysis. Our models resulted in hind‐cast (1989–2003) predictions of net population growth and range expansion that closely matched observed patterns. We next made projections of future range expansion and population growth, incorporating uncertainty in all model parameters, and explored the sensitivity of model predictions to variation in spatially explicit survival and dispersal rates. The predicted rate of southward range expansion (median = 5.2 km/yr) was sensitive to both dispersal and survival rates; elasticity analysis indicated that changes in adult survival would have the greatest potential effect on the rate of range expansion, while perturbation analysis showed that variation in subadult dispersal contributed most to variance in model predictions. Variation in survival and dispersal of females at the south end of the range contributed most of the variance in predicted southward range expansion. Our approach provides guidance for the acquisition of further data and a means of forecasting the consequence of specific management actions. Similar methods could aid in the management of other recovering populations.
MAPPING “OLD” VS. “YOUNG” PIÑON–JUNIPER STANDS WITH A PREDICTIVE TOPO‐CLIMATIC MODEL
Authors: Jacobs B. F. , Romme W. H. , Allen C. D.
Published: September 2008

Piñon pine and juniper woodlands in the southwestern United States are often represented as an expanding and even invasive vegetation type, a legacy of historic grazing, and culpable in the degradation of western rangelands. A long‐standing emphasis on forage production, in combination with recent hazard fuel concerns, has prompted a new era of woodland management with stated restoration objectives. Yet the extent and dynamics of piñon–juniper communities that predate intensive Euro‐American settlement activities are poorly known or understood, while the intrinsic ecological, aesthetic, and economic values of old‐growth woodlands are often overlooked. Historical changes in piñon–juniper stands include two related, but poorly differentiated processes: recent tree expansion into grass‐ or shrub‐dominated (i.e., non‐woodland) vegetation and thickening or infilling of savanna or mosaic woodlands predating settlement. Our work addresses the expansion pattern, modeling the occurrence of “older” savanna and woodland stands extant prior to 1850 in contrast to “younger” piñon–juniper growth of more recent, postsettlement origin. We present criteria in the form of a diagnostic key for distinguishing “older,” pre‐Euro‐American settlement piñon–juniper from “younger” (post‐1850) stands and report results of predictive modeling and mapping efforts within a north‐central New Mexico study area. Selected models suggest a primary role for soil moisture in the current distribution of “old” vs. “young” piñon–juniper stands. Presettlement era woodlands are shown to occupy a discrete ecological space, defined by the interaction of effective (seasonal) moisture with landform setting and fine‐scale (soil/water) depositional patterns. “Older” stands are generally found at higher elevations or on skeletal soils in upland settings, while “younger” stands (often dominated by one‐seed juniper,Juniperus monosperma) are most common at lower elevations or in productive, depositional settings. Modeling at broad regional scales can enhance our general understanding of piñon–juniper ecology, while predictive mapping of local areas has potential to provide products useful for land management. Areas of the southwestern United States with strong monsoonal (summer moisture) patterns appear to have been the most susceptible to historical woodland expansion, but even here the great majority of extant piñon–juniper has presettlement origins (although widely thickened and infilled historically), and old‐growth structure is not uncommon in appropriate upland settings.
EXPLOITATION AND DESTABILIZATION OF A WARM, FRESHWATER ECOSYSTEM THROUGH ENGINEERED HYDROLOGICAL CHANGE
Authors: Hambright K. David , Zohary Tamar , Eckert Werner , Schwartz Steven S. , Schelske Claire L. , Laird Kathleen R. , Leavitt Peter R.
Published: September 2008

Exploitation of freshwater resources is having catastrophic effects on the ecological dynamics, stability, and quality of those water resources on a global scale, especially in arid and semiarid regions. Lake Kinneret, Israel (the Biblical Sea of Galilee), the only major natural freshwater lake in the Middle East, has been transformed functionally into a reservoir over the course of ∼70 years of hydrological alterations aimed mostly at producing electrical power and increasing domestic and agricultural water supply. Historical changes in lake chemistry and biology were reconstructed using analysis of sedimentary nutrient content, stable and radioisotope composition, biochemical and morphological fossils from algae, remains of aquatic invertebrates, and chemical indices of past light regimes. Together, these paleolimnological analyses of the lake's bottom sediments revealed that this transformation has been accompanied by acceleration in the rate of eutrophication, as indicated by increased accumulation rates of phosphorus, nitrogen, organic matter, phytoplankton and bacterial pigments, and remains of phytoplankton and zooplankton. Substantial increases in these indices of eutrophication coincide with periods of increased water‐level fluctuations and drainage of a major upstream wetland in the early to middle 20th century and suggest that management of the lake for increased water supply has degraded water quality to the point that ecosystem stability and sustainability are threatened. Such destabilization may be a model for eutrophication of freshwater lakes in other arid regions of the world in which management emphasizes water quantity over quality.
IMPACT OF NUTRIENT REMOVAL THROUGH HARVESTING ON THE SUSTAINABILITY OF THE BOREAL FOREST
Authors: Duchesne Louis , Houle Daniel
Published: September 2008

The cycling of base cations (K, Ca, Mg, and Na) was investigated in a boreal balsam fir forest (the Lake Laflamme Watershed) between 1999 and 2005. Base cation budgets were calculated for the soil rooting zone that included atmospheric deposition and soil leaching losses, two scenarios of tree uptake (whole‐tree and stem‐only harvesting), and three scenarios of mineral weathering, leading to six different scenarios. In every scenario there was a net accumulation of Mg within the soil exchangeable reservoir, while Ca accumulated in four scenarios. Potassium was lost in five of the six scenarios. Contrary to Ca and Mg, immobilization of K within tree biomass (69 mol·ha−1·yr−1) was the main pathway of K losses from the soil exchangeable reservoir, being five times higher than losses via soil leaching (14 mol·ha−1·yr−1). The amounts of K contained within the aboveground biomass and the exchangeable soil reservoir were 3.3 kmol/ha and 4.2 kmol/ha, respectively. Whole‐tree harvesting may thus remove 44% of the K that is readily available for cycling in the short term, making this forest sensitive to commercial forestry operations. Similar values of annual K uptake as well as a similar distribution of K between tree biomass and soil exchangeable reservoirs at 14 other coniferous sites, distributed throughout the boreal forest of Québec, suggest that the Lake Laflamme Watershed results can be extrapolated to a much larger area. Stem‐only harvesting, which would reduce K exports due to biomass removal by 60%, should be used for these types of forest.
NITROGEN RETENTION IN URBAN LAWNS AND FORESTS
Authors: Raciti S. M. , Groffman P. M. , Fahey T. J.
Published: September 2008

Lawns are a dominant cover type in urban ecosystems, and there is concern about their impacts on water quality. However, recent watershed‐level studies suggest that these pervious areas might be net sinks, rather than sources, for nitrogen (N) in the urban environment. A 15N pulse‐labeling experiment was performed on lawn and forest plots in the Baltimore (Maryland, USA) metropolitan area to test the hypothesis that lawns are a net sink for atmospheric‐N deposition and to compare and contrast mechanisms of N retention in these vegetation types. A pulse of 15N‐NO3−, simulating a precipitation event, was followed through mineral soils, roots, Oi‐layer/thatch, aboveground biomass, microbial biomass, inorganic N, and evolved N2 gas over a one‐year period. The 15N label was undetectable in gaseous samples, but enrichment of other pools was high. Gross rates of production and consumption of NO3− and NH4+ were measured to assess differences in internal N cycling under lawns and forests. Rates of N retention were similar during the first five days of the experiment, with lawns showing higher N retention than forests after 10, 70, and 365 days. Lawns had larger pools of available NO3− and NH4+; however, gross rates of mineralization and nitrification were also higher, leading to no net differences in NO3− and NH4+ turnover times between the two systems. Levels of 15N remained steady in forest mineral soils from day 70 to 365 (at 23% of applied 15N), but continued to accumulate in lawn mineral soils over this same time period, increasing from 20% to 33% of applied 15N. The dominant sink for N in lawn plots changed over time. Immobilization in mineral soils dominated immediately (one day) after tracer application (42% of recovered 15N); plant biomass dominated the short term (10 days; 51%); thatch and mineral‐soil pools together dominated the medium term (70 days; 28% and 36%, respectively); and the mineral‐soil pool alone dominated long‐term retention (one year; 70% of recovered 15N). These findings illustrate the mechanisms whereby urban and suburban lawns under low to moderate management intensities are an important sink for atmospheric‐N deposition.
CHANGES IN THE DISSOLVED NITROGEN POOL ACROSS LAND COVER GRADIENTS IN WISCONSIN STREAMS
Authors: Stanley Emily H. , Maxted Jeffrey T.
Published: September 2008

Increases in anthropogenic nitrogen fixation have resulted in wide‐scale enrichment of aquatic ecosystems. Existing biogeochemical theory suggests that N enrichment is associated with increasing concentrations of nitrate; however, dissolved organic nitrogen (DON) is often a major component of the total dissolved nitrogen (TDN) pool in streams and rivers, and its concentration can be significantly elevated in human‐influenced basins. We examined N concentrations during summer base flow conditions in 324 Wisconsin streams to determine whether DON was a significant component of TDN and how its relative contribution changed across a gradient of increasing human (agriculture and urban) land use for 84 of these sites. Total dissolved nitrogen varied from 0.09 to 20.74 mg/L, and although DON was significantly higher in human‐dominated basins relative to forested and mixed‐cover basins, its concentration increased relatively slowly in response to increasing human land cover. This limited response reflected a replacement of wetland‐derived DON in low‐N streams by anthropogenic sources in human‐dominated sites, such that net changes in DON were small across the land use gradient. Nitrate‐N increased exponentially in response to greater human land cover, and NH4‐N and NO2‐N were present at low levels. Nitrite‐N exceeded NH4‐N at 20% of sites and reached a maximum concentration of 0.10 mg/L. This examination suggests that basic mechanisms driving N losses from old‐growth forests subject to N saturation also shape the summertime N pool in Wisconsin streams, in addition to other processes dictated by landscape context. The overwhelming role of human land use in determining the relative and absolute composition of the summertime N pool included (1) rapid increases in NO3‐N, (2) limited changes in DON, and (3) the unexpected occurrence of NO2‐N. High (>3 mg/L) TDN conditions dominated by NO3‐N, regardless of landscape context or forms of N inputs, indicate a state of “N hypersaturation,” which appears to be increasingly common in human‐influenced streams and rivers. Many sites in agriculturally rich areas had NO2‐N and NO3‐N concentrations that, if sustained, are at chronically toxic levels for sensitive aquatic biota, suggesting that N enrichment now has local consequences for resident stream biota in addition to contributing to coastal eutrophication.
USING NETWORK CENTRALITY MEASURES TO MANAGE LANDSCAPE CONNECTIVITY
Authors: Estrada Ernesto , Bodin Örjan
Published: September 2008

We use a graph‐theoretical landscape modeling approach to investigate how to identify central patches in the landscape as well as how these central patches influence (1) organism movement within the local neighborhood and (2) the dispersal of organisms beyond the local neighborhood. Organism movements were theoretically estimated based on the spatial configuration of the habitat patches in the studied landscape. We find that centrality depends on the way the graph‐theoretical model of habitat patches is constructed, although even the simplest network representation, not taking strength and directionality of potential organisms flows into account, still provides a coarse‐grained assessment of the most important patches according to their contribution to landscape connectivity. Moreover, we identify (at least) two general classes of centrality. One accounts for the local flow of organisms in the neighborhood of a patch, and the other accounts for the ability to maintain connectivity beyond the scale of the local neighborhood. Finally, we study how habitat patches with high scores on different network centrality measures are distributed in a fragmented agricultural landscape in Madagascar. Results show that patches with high degree and betweenness centrality are widely spread, while patches with high subgraph and closeness centrality are clumped together in dense clusters. This finding may enable multispecies analyses of single‐species network models.
UNDERSTANDING THE NET EFFECTS OF PESTICIDES ON AMPHIBIAN TREMATODE INFECTIONS
Authors: Rohr Jason R. , Raffel Thomas R. , Sessions Stanley K. , Hudson Peter J.
Published: September 2008

Anthropogenic factors can have simultaneous positive and negative effects on parasite transmission, and thus it is important to quantify their net effects on disease risk. Net effects will be a product of changes in the survival and traits (e.g., susceptibility, infectivity) of both hosts and parasites. In separate laboratory experiments, we exposed cercariae of the trematode Echinostoma trivolvis, and its first and second intermediate hosts, snails (Planorbella trivolvis) and green frog tadpoles (Rana clamitans), respectively, to one of four common pesticides (atrazine, glyphosate, carbaryl, and malathion) at standardized, ecologically relevant concentrations (201.0, 3700.0, 33.5, and 9.6 μg/L, respectively). We measured effects of pesticide exposure on six mechanisms important to this host–parasite interaction: (1) survival of E. trivolvis cercariae over 26 hours, (2) tadpole survival over two weeks, (3) snail survival over four weeks, (4) snail growth and fecundity, (5) cercarial infectivity, and (6) tadpole susceptibility to a fixed number of cercariae. Pesticides, in general, caused significantly greater mortality of E. trivolvis cercariae than did control treatments, but atrazine was the lone chemical to significantly reduce cercarial survival (LC50 value = 267 mg/L) and then only at concentrations greater than commonly found in aquatic ecosystems (≥200 μg/L). None of the pesticides significantly enhanced E. trivolvis virulence, decreased tadpole survival, or reduced snail survival, growth, or fecundity. Sublethal exposure of the cercariae to the pesticides (4 h) did not significantly affect trematode encystment in R. clamitans. In contrast, sublethal exposure of R. clamitans to each of the four pesticides increased their susceptibility as measured by the percentage of cercariae that encysted. The reduction in exposure to trematodes due to pesticide‐induced cercarial mortality (a density‐mediated effect) was smaller than the pesticide‐induced increase in amphibian susceptibility (a trait‐mediated effect), suggesting that the net effect of exposure to environmentally realistic levels of pesticides will be to elevate amphibian trematode infections. These findings highlight the importance of elucidating the lethal and sublethal effects of anthropogenic factors on both hosts and parasites to understand the mechanisms underlying changes in parasite transmission and virulence, an approach that is especially needed for amphibians, a taxon experiencing global disease‐related declines.
CHARACTERIZING THE SPATIAL STRUCTURE OF SONGBIRD CULTURES
Authors: Laiolo Paola
Published: September 2008

Recent advances have shown that human‐driven habitat transformations can affect the cultural attributes of animal populations in addition to their genetic integrity and dynamics. Here I propose using the song of oscine birds for identifying the cultural spatial structure of bird populations and highlighting critical thresholds associated with habitat fragmentation. I studied song variation over a wide geographical scale in a small and endangered passerine, the Dupont's LarkChersophilus duponti, focusing on (1) cultural population structure, to determine a statistical representation of spatial variation in song and identify cultural units, and (2) the minimum patch size needed for an individual to develop a stable repertoire. I found that overall song diversity depends on variation among populations (beta‐cultural diversity). Abrupt thresholds occurred in the relationships between individual song dissimilarity and geographic distance, and between individual song diversity and patch area. Spatial autocorrelation analysis showed that populations located as little as 5 km apart may have independently evolved their song traditions. Song diversity stabilized in patches as small as 100 ha supporting as few as 8–20 males. Song repertoires of smaller patches were significantly poorer. Almost one‐quarter of the study populations inhabited patches <100 ha, and their cultural traditions appear to have eroded. The analysis of spatial patterns in birdsong may be a useful tool for detecting subpopulations prone to extinction.
FINE‐SCALE HABITAT MODELING OF A TOP MARINE PREDATOR: DO PREY DATA IMPROVE PREDICTIVE CAPACITY
Authors: Torres Leigh G. , Read Andrew J. , Halpin Patrick
Published: September 2008

Predators and prey assort themselves relative to each other, the availability of resources and refuges, and the temporal and spatial scale of their interaction. Predictive models of predator distributions often rely on these relationships by incorporating data on environmental variability and prey availability to determine predator habitat selection patterns. This approach to predictive modeling holds true in marine systems where observations of predators are logistically difficult, emphasizing the need for accurate models. In this paper, we ask whether including prey distribution data in fine‐scale predictive models of bottlenose dolphin (Tursiops truncatus) habitat selection in Florida Bay, Florida, USA, improves predictive capacity. Environmental characteristics are often used as predictor variables in habitat models of top marine predators with the assumption that they act as proxies of prey distribution. We examine the validity of this assumption by comparing the response of dolphin distribution and fish catch rates to the same environmental variables. Next, the predictive capacities of four models, with and without prey distribution data, are tested to determine whether dolphin habitat selection can be predicted without recourse to describing the distribution of their prey. The final analysis determines the accuracy of predictive maps of dolphin distribution produced by modeling areas of high fish catch based on significant environmental characteristics. We use spatial analysis and independent data sets to train and test the models. Our results indicate that, due to high habitat heterogeneity and the spatial variability of prey patches, fine‐scale models of dolphin habitat selection in coastal habitats will be more successful if environmental variables are used as predictor variables of predator distributions rather than relying on prey data as explanatory variables. However, predictive modeling of prey distribution as the response variable based on environmental variability did produce high predictive performance of dolphin habitat selection, particularly foraging habitat.