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Estimated

Distribution by Scientific Domains
Medical Sciences46%
Life Sciences18%
Business, Economics, Finance and Accounting6%
Engineering6%
Chemistry6%
Humanities and Social Sciences5%
Earth and Environmental Science4%
Polymers and Materials Science2%
4 Other Domains7%
Distribution within Medical Sciences
Dermatology4%
39 Other Subdomains88%

Terms modified by Estimated

  • estimated abundance
  • estimated age
  • estimated average requirement
  • estimated blood loss
  • estimated coefficient
  • estimated concentration
  • estimated cost
  • estimated effect
    		•
  • estimated elasticity
  • estimated error
  • estimated gfr
  • estimated glomerular filtration rate
  • estimated incidence
  • estimated model
  • estimated models
  • estimated number
    		•
  • estimated odds ratio
  • estimated parameter
  • estimated population
  • estimated prevalence
  • estimated probability
  • estimated proportion
  • estimated rate
  • estimated risk
    		•
  • estimated solvent content
  • estimated survival
  • estimated temperature
  • estimated time
  • estimated total
  • estimated value

    • Selected Abstracts

    Documenting Loss of Large Trophy Fish from the Florida Keys with Historical Photographs

    CONSERVATION BIOLOGY, Issue 3 2009
    LOREN McCLENACHAN
    arrecifes de coral; ecología histórica; directrices cambiantes; peces de arrecife; sobrepesca Abstract:,A loss of large vertebrates has occurred in aquatic and terrestrial ecosystems, but data to measure long-term population changes are sparse. Historical photographs provide visual and quantitative evidence of changes in mean individual size and species composition for groups of marine fish that have been targeted by sport fishing. I measured such trends for 13 groups of recreationally caught "trophy" reef fish with photographs taken in Key West, Florida, from 1956 to 2007. The mean fish size declined from an estimated 19.9 kg (SE 1.5) to 2.3 kg (SE 0.3), and there was a major shift in species composition. Landings from 1956 to 1960 were dominated by large groupers (Epinephelus spp.), and other large predatory fish were commonly caught, including sharks with an average length of just <2 m. In contrast, landings in 2007 were composed of small snappers (Lutjanus spp. and Ocyurus chrysurus) with an average length of 34.4 cm (SE 0.62), and the average length of sharks declined by more than 50% over 50 years. Major declines in the size of fish caught were not reflected in the price of fishing trips, so customers paid the same amount for a less-valuable product. Historical photographs provide a window into a more pristine coral reef ecosystem that existed a half a century ago and lend support to current observations that unfished reef communities are able to support large numbers of large-bodied fish. Resumen:,Una pérdida de vertebrados mayores ha ocurrido en ecosistemas acuáticos y terrestres, pero los datos para medir los cambios poblaciones a largo plazo son escasos. Las fotografías históricas proporcionan evidencia visual y cuantitativa de cambios en el tamaño individual promedio y de la composición de especies en grupos de peces marinos que han sido blanco de la pesca deportiva. Medí esas tendencias en 13 grupos de peces de arrecife capturados recreativamente como "trofeos" mediante fotografías tomadas en Key West, Florida, desde 1956 a 2007. El peso promedio de los peces declinó de unos 19.9 kg (ES 1.5) a 2.3 kg (ES 0.3), y hubo un cambio mayor en la composición de especies. Las capturas entre 1956 y 1960 estuvieron dominadas por meros (Epinephelus spp.) grandes, y otros peces depredadores eran capturados comúnmente, incluyendo tiburones con una longitud promedio de poco menos de 2m. En contraste, las capturas en 2007 fueron compuestas de pargos (Lutjanus spp. y Ocyurus chrysurus) pequeños con una longitud promedio de 34.4 cm (ES 0.62), y la longitud promedio de los tiburones declinó más de 50% en 50 años. La gran declinación en el tamaño de los peces capturados no se reflejó en los precios de los viajes de pesca, así que los clientes pagaron la misma cantidad por un producto menos valioso. Las fotografías históricas proporcionan una visión de un ecosistema arrecifal coralino prístino que existió hace medio siglo y proporcionan soporte a los comentarios actuales de que las comunidades arrecifales no explotadas son capaces de soportar numerosos peces de talla grande. [source]

    Mexico's Community-Managed Forests as a Global Model for Sustainable Landscapes

    CONSERVATION BIOLOGY, Issue 3 2003
    David Barton Bray
    On the other hand, conservationists have declared that the only way to stem the tide of deforestation is to place as many tracts as possible under strict protection. In this context, Mexico presents a national laboratory for studying the social and ecological benefits of delivering forests to local people. As a little-noticed result of the Mexican Revolution in the second decade of the twentieth century, well over half of the forests of Mexico were placed in community-held lands. In historic struggles that passed through several phases, most of these communities have now gained substantial control over the use of their forests. Because of the substantial degree of social capital in rural forms of organization in Mexico, this control of forest resources has led to an estimated 290,479 community forest enterprises ( CFEs ), through which communities are producing timber on their own lands. New studies are beginning to suggest that important gains in both social and economic justice, good forest management, and biodiversity protection are resulting from the actions of these CFEs. As more forests globally are being devolved to local communities, it is important to carry out more research on the Mexican model of community forest management for timber production. Resumen: Investigadores preocupados por el manejo sostenible de bosques en los trópicos han argumentado que el camino para una custodia mas efectiva de los recursos forestales es la transferencia de la responsabilidad a las comunidades locales que obtienen sustento de ellos. Por otro lado, conservacionistas han declarado que la única manera de detener la ola de deforestación es colocar bajo protección estricta tantas regiones como sea posible. En este contexto, México representa un laboratorio para el estudio de los beneficios sociales y ecológicos de entregar los bosques a los habitantes locales. Como un resultado poco conocido de la Revolución Mexicana, en la segunda década del siglo veinte, más de la mitad de los bosques de México se ubicaban en tierras que estaban en manos de las comunidades. Las comunidades forestales han atravesado por distintas etapas de conflicto, tras la cuáles han obtendio un control sustancial de los usos de sus bosques. Debido al nivel considerable de capital social en formas de organización rural en México, este control de los recursos forestales ha conducido a la integración de entre 290,479 empresas forestales comunitarias ( EFC ), en las que las comunidades están produciendo madera en sus propias tierras. Nuevos estudios están comenzando a sugerir que se están produciendo ganancias importantes en las acciones de estas EFC están generando beneficios importantes, tanto en lo que se refiere a justicia social como económica, la administración correcta de bosques y la protección de la biodiversidad. A medida en que se deleguen mayores extensiones de bosques a comunidades locales, es importante llevar a cabo más investigación sobre el modelo mexicano de manejo comunitario de bosques para la producción de forestal maderable. [source]

    Care for the Adult Family Members of Victims of Unexpected Cardiac Death

    ACADEMIC EMERGENCY MEDICINE, Issue 12 2006
    Robert Zalenski MD
    Abstract More than 300,000 sudden coronary deaths occur annually in the United States, despite declining cardiovascular death rates. In 2000, deaths from heart disease left an estimated 190,156 new widows and 68,493 new widowers. A major unanswered question for emergency providers is whether the immediate care of the loved ones left behind by the deceased should be a therapeutic task for the staff of the emergency department in the aftermath of a fatal cardiac arrest. Based on a review of the literature, the authors suggest that more research is needed to answer this question, to assess the current immediate needs and care of survivors, and to find ways to improve care of the surviving family of unexpected cardiac death victims. This would include improving quality of death disclosure, improving care for relatives during cardiopulmonary resuscitation of their family member, and improved methods of referral for services for prevention of psychological and cardiovascular morbidity during bereavement. [source]

    Performance of calibration standards for antigen quantitation with flow cytometry in chronic lymphocytic leukemia

    CYTOMETRY, Issue 6 2007
    Eva D. Rossmann
    Abstract Background: The fluorescence intensities of CD3, CD4 on T cells and CD20, CD22 molecules on B cells were quantitatively measured on lymphocytes from chronic lymphocytic leukemia (CLL) patients and healthy donors. Methods: The performance of three different types of microbeads was compared, i.e. Quantum molecules of equivalent soluble fluorochrome (Q-MESF), Quantum simply cellular (QSC), and QuantiBRITEÔ (QB). As all PE-conjugates had a F/P ratio of 1:1, the MESF units represented also the antibody binding capacity (ABC). Results: The ABCs of CD4 and CD20 antigens estimated with QSC (ABCQSC) were higher than those assigned with QB (ABCQB) with an average difference 49%. Higher numbers of antigenic sites were obtained with Q-MESF than with QSC for CD20 antigen. On the contrary, CD4 antigenic sites numbers estimated with QSC were higher than those estimated with Q-MESF. ABC values estimated with Quantum MESF PE (ABCQ-MESF) were ,15% higher than ABCQSC, whereas ABCQ-MESF was ,49% higher than ABCQB. Statistically significant correlations were found between the values obtained using various standards. The present study is the first to report down-regulation of CD3 antigen on T cells from patients with CLL. Conclusions: This study emphasizes the relevance of quantitative measurement of fluorescence intensity by flow cytometry as a standardized approach to measure and interpret the expression of some CLL markers and reduce variability of results obtained at different sites in multi-center clinical studies. © 2007 Clinical Cytometry Society [source]

    Recent Trends in Cosmetic and Surgical Procedure Volumes in Dermatologic Surgery

    DERMATOLOGIC SURGERY, Issue 9 2009
    EMILY P. TIERNEY MD
    BACKGROUND The number of cosmetic and noncosmetic surgical procedures performed by dermatologic surgeons has been rising rapidly, but there are few consistent data sources allowing procedure volumes to be tracked over time. METHODS American Society for Dermatologic Surgery member survey in 2001 to 2007 reporting cosmetic and noncosmetic procedural volumes (300,500 surgeons surveyed, response rate of 31,44%). RESULTS In 2001, dermatologic surgeons performed an estimated 3.4 million cosmetic and noncosmetic surgical procedures; in 2007, it was estimated that a total of 7.6 million procedures were performed (120.2% rate of growth between 2001 and 2007). The procedures with the greatest increase during this time period were soft tissue augmentation (405.0% increase), botulinum toxin injections (324.4% increase), and nonablative skin rejuvenation (laser, light, and radiofrequency sources) (330.7% increase). More modest increases were noted in skin cancer procedures (85.8% increase) and ablative resurfacing procedures (66.8% increase). CONCLUSION The magnitude of growth in procedural volumes over the last 8 years reflects the advancements in dermatologic surgery in treatments for skin cancer and in treatment of photoaging and cosmetic enhancement of the skin. [source]

    Energy requirements of spasticity

    DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 4 2001
    Cheryl Hemingway MBCh B
    Direct measurement of energy expended by spasticity in children with severe spastic quadriparesis is difficult. Insertion of an intrathecal baclofen pump in a 13-year-old boy with severe spasticity and profound mental retardation* resulted in an estimated 30 to 40% decrease in his spasticity. As he had been on a carefully calculated ketogenic diet and fed by gastrostomy, his precise caloric intake was known. Decrease in spasticity, on the same caloric intake, led to marked weight gain. Reduction of 100 calories intake resulted in new weight stability. It was possible therefore, to estimate indirectly energy used by his spasticity. This 100 calories, representing 34% of calories above his resting energy requirement, corresponded to an independently estimated 30 to 40% of caloric expenditure of his spasticity. It was concluded that when calculation of calories is critical, energy utilization by spasticity must be taken into consideration. [source]

    Quality of diabetes care in patients with schizophrenia and bipolar disorder: cross-sectional study

    DIABETIC MEDICINE, Issue 12 2007
    S. Whyte
    Abstract Aims To determine whether patients with severe mental illness receive poorer health care for diabetes than patients without. Methods This population-based cross-sectional survey used electronic general practice records from 481 UK general practices contributing to the QRESEARCH database. The records of 11 043 patients with diabetes, drawn from a database population of over 9 million patients, were extracted. Unadjusted and adjusted odds ratios were calculated using unconditional logistic regression for each of 17 quality indicators for diabetes care from the new General Medical Services contract for general practitioners. Results The presence of severe mental illness did not reduce the quality of care received; the only significant difference between groups showed that such patients were more likely to have glycated haemoglobin < 7.5%[adjusted odds ratio = 1.45 (99% confidence interval 1.20,1.76)]. Increasing age was associated with better care [adjusted odds ratios from 1.06 (1.02,1.11) to 1.61 (1.52,1.70)], but other confounding variables had no consistent effect across indicators. Overall, performance against government targets was good. Conclusions The hypothesis of poorer diabetes care for those with severe mental illness is disproved, perhaps surprisingly, in the light of other recent UK studies showing inequalities in care for the mentally ill. The study does not reveal who is providing this good care (general practitioners, psychiatrists or diabetologists) or take account of the estimated 600 000 people in the UK with undiagnosed diabetes. [source]

    Development of partial rock veneers by root throw in a subalpine setting

    EARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2006
    W. R. Osterkamp
    Abstract Rock veneers stabilize hillslope surfaces, occur especially in areas of immature soil, and form through a variety of process sets that includes root throw. Near Westcliffe, Colorado, USA, data were collected from a 20 × 500 m transect on the east slope of the Sangre de Cristo Mountains. Ages of pit/mound complexes with rock fragments exposed at the surface by root throw ranged from recent (freshly toppled tree) to unknown (complete tree decay). Calculations based on dimensions of the pit/mound complexes, estimated time of tree toppling, sizes of exposed rock fragments, and percentage rock covers at pit/mound complexes, as well as within the transect area, indicate that recent rates of root throw have resulted in only partial rock veneering since late Pleistocene deglaciation. Weathering of rock fragments prevents development of an extensive rock veneer and causes a balance, achieved within an estimated 700 years, between the rates of rock-fragment exposure by root throw and clast disintegration by chemical reduction. The estimated rate of rock-fragment reduction accounts for part of the fluvial sediment yields observed for forested subalpine areas of western North America. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Exposure to cannabis in popular music and cannabis use among adolescents

    ADDICTION, Issue 3 2010
    Brian A. Primack
    ABSTRACT Background Cannabis use is referenced frequently in American popular music, yet it remains uncertain whether exposure to these references is associated with actual cannabis use. We aimed to determine if exposure to cannabis in popular music is associated independently with current cannabis use in a cohort of urban adolescents. Methods We surveyed all 9th grade students at three large US urban high schools. We estimated participants' exposure to lyrics referent to cannabis with overall music exposure and content analyses of their favorite artists' songs. Outcomes included current (past 30 days) and ever use of cannabis. We used multivariable regression to assess independent associations between exposures and outcomes while controlling for important covariates. Results Each of the 959 participants was exposed to an estimated 27 cannabis references per day [correction added on 19 January 2010, after first online publication: 40 has been changed to 27] (standard deviation = 73 [correction added on 19 January 2010, after first online publication: 104 has been changed to 73]). Twelve per cent (n = 108) were current cannabis users and 32% (n = 286) had ever used cannabis. Compared with those in the lowest tertile of total cannabis exposure in music, those in the highest tertile of exposure were almost twice as likely to have used cannabis in the past 30 days (odds ratio = 1.83; 95% confidence interval = 1.04, 3.22), even after adjusting for socio-demographic variables, personality characteristics and parenting style. As expected, however, there was no significant relationship between our cannabis exposure variable and a sham outcome variable of alcohol use. Conclusions This study supports an independent association between exposure to cannabis in popular music and early cannabis use among urban American adolescents. [source]

    From Great Depression to Great Credit Crisis: similarities, differences and lessons

    ECONOMIC POLICY, Issue 62 2010
    Miguel Almunia
    Summary The Great Depression of the 1930s and the Great Credit Crisis of the 2000s had similar causes but elicited strikingly different policy responses. While it remains too early to assess the effectiveness of current policy, it is possible to analyse monetary and fiscal responses in the 1930s as a natural experiment or counterfactual capable of shedding light on the impact of current policies. We employ vector autoregressions, instrumental variables, and qualitative evidence for 27 countries in the period 1925,39. The results suggest that monetary and fiscal stimulus was effective -- that where it did not make a difference it was not tried. They shed light on the debate over fiscal multipliers in episodes of financial crisis. They are consistent with multipliers at the higher end of those estimated in the recent literature, and with the argument that the impact of fiscal stimulus will be greater when banking systems are dysfunctional and monetary policy is constrained by the zero bound. --- Miguel Almunia, Agustín Bénétrix, Barry Eichengreen, Kevin H. O'Rourke and Gisela Rua [source]

    Flow-through partial-filling affinity capillary electrophoresis can estimate binding constants of neutral ligands to receptors via a competitive assay technique

    ELECTROPHORESIS, Issue 6 2003
    John Kaddis
    Abstract This work evaluates the use of a competitive binding assay using flow-through partial-filling affinity capillary electrophoresis (FTPFACE) to estimate binding constants of neutral ligands to a receptor. We demonstrate this technique using, as a model system, carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides. In this technique, the capillary is first partially filled with a negatively charged ligand, a sample containing CAB and two noninteracting standards, and a neutral ligand, then electrophoresed. Upon application of a voltage the sample plug migrates into the plug of negatively charged ligand (L,) resulting in the formation of a CAB-L, complex. Continued electrophoresis results in mixing between the neutral ligand (L0) and the CAB-L, complex. L0 successfully competes out L, to form the new CAB-L0 complex. Analysis of the change in the relative migration time ratio (RMTR) of CAB relative to the noninteracting standards, as a function of neutral ligand concentration, yields a value for the binding constant. These values are in agreement with those estimated using other binding and ACE techniques. Data demonstrating the quantitative potential of this method is presented. [source]

    A dynamic mass budget for toxaphene in North America

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002
    Matthew MacLeod
    Abstract A continental-scale dynamic mass budget for toxaphene in North America is presented, based on available information on physicochemical properties, usage patterns, and reported environmental concentrations and using the Berkeley-Trent North American mass balance contaminant fate model (BETR North America). The model describes contaminant fate in 24 ecological regions of North America, including advective transport between regions in the atmosphere, freshwater, and near-shore coastal water. The dynamic mass budget accounts for environmental partitioning, transport, and degradation of the estimated 534 million kg of toxaphene that were used in North America as an insecticide and piscicide between 1945 and 2000. Satisfactory agreement exists between model results and current and historically reported concentrations of toxaphene in air, water, soil, and sediments throughout North America. An estimated 15 million kg of toxaphene are believed to remain in active circulation in the North American environment in the year 2000, with the majority in soils in the southern United States and Mexico, where historic usage was highest. Approximately 70% of total toxaphene deposition from the atmosphere to the Great Lakes is attributed to sources outside the Great Lakes Basin, and an estimated total of 3.9 million kg of toxaphene have been transported to this region from other parts of the continent. The toxaphene mass budget presented here is believed to be the first reported continental-scalemultimedia mass budget for any contaminant. [source]

    Growing Up in Guerrilla Camp: The long-Term Impact of Being a Child Soldier in El Salvador's Civil War

    ETHOS, Issue 4 2002
    Julia Dickson-Gõmez
    Many recent wars are characterized by high levels of civilian casualties, a large proportion of whom are women and children. Furthermore, an estimated 300,000 children are actively participating in 36 ongoing or recently ended conflicts around the world. However, there is a dearth of research on the long-term effects of war trauma experienced in childhood or children's active participation in armed conflicts. This article explores the long-term effects of children's active participation in the war in El Salvador by examining four young adults who fought with the guerrilla army as children and adolescents. Comparing these four cases with members of the community who joined and fought with the guerrilla as adults, it will be argued that traumatic experiences were even more devastating when they occurred in early childhood as they destroyed the ability to establish basic trust in competent and nurturing caretakers. Becoming a soldier created additional conflicts as these adolescent soldiers behaved in ways they felt were morally incorrect. Adolescent soldiers were also not given the opportunity to develop autonomy and learn adult peace-time roles. Both the psychological trauma suffered as children as well as continued economic scarcity and violence contribute to these campesinos' difficulties in creating meaningful lives as adults. [source]

    Injuries Related to Snow Blowers in the United States: 2002 Through 2008

    ACADEMIC EMERGENCY MEDICINE, Issue 5 2010
    Bart Hammig PhD
    Abstract Objectives:, The objective was to examine injuries related to the use of a snow blower among patients treated in an emergency department (ED). Methods:, Data were obtained from the National Electronic Injury Surveillance System (NEISS) for the years 2002,2008. National estimates of ED visits for injuries associated with the use of a snow blower were obtained, and descriptive epidemiologic characteristics assessed. Results:, From 2002 through 2008, there were an estimated 32,307 ED visits for injuries related to the use of a snow blower in the United States. Older adults had a higher proportion of ED visits for such injuries than younger age groups. The majority of injuries involved injuries to the hand, with 42% of cases diagnosed with fractures and 20% resulting in amputations. Conclusions:, Findings indicate that injuries from snow blowers remain a public health problem. Efforts to reduce injury incidence are discussed in accordance with inherent challenges of prevention of injuries associated with these products. ACADEMIC EMERGENCY MEDICINE 2010; 17:566,569 © 2010 by the Society for Academic Emergency Medicine [source]

    Epidemiological study of acute encephalitis in Tottori Prefecture, Japan

    EUROPEAN JOURNAL OF NEUROLOGY, Issue 10 2008
    K. Wada-Isoe
    Background and purpose:, To conduct an epidemiological survey of acute encephalitis focusing on non-herpetic acute limbic encephalitis (NHALE) in Tottori Prefecture, western area of Japan. Methods:, A questionnaire survey on the annual number of patients aged 16 years or more with acute encephalitis from 2001 to 2005 was undertaken in 2006. Results:, During the study period, 49 patients were diagnosed with acute encephalitis. The subtype of acute encephalitis was as follows: 10 patients with herpes simplex encephalitis (HSE), 12 patients with NHALE, 4 patients with paraneoplastic encephalitis, 2 patients with encephalitis associated with collagen disease, one patient with viral encephalitis other than HSE, 20 patients with encephalitis with unknown causes. The service-based incidence rate of acute encephalitis was 19.0 per million person-years. The incidence rate of NHALE subtype was 4.7 per million person-years. Conclusions:, Our epidemiological survey indicated an estimated 550 patients would develop NHALE per year in Japan, suggesting that NHALE may not be a rare disorder. [source]

    Curling Iron-related Injuries Presenting to U.S. Emergency Departments

    ACADEMIC EMERGENCY MEDICINE, Issue 4 2001
    Khajista Qazi MD
    Abstract. Objective: To describe curling iron-related injuries reported to the National Electronic Injury Surveillance System (NEISS) between January 1, 1992, and December 31, 1996. Methods: The authors retrospectively reviewed data from NEISS, a weighted probability sample of emergency departments (EDs) developed to monitor consumer product-related injuries. The information reported includes patient demographics, injury diagnosis, body part injured, incident locale, patient disposition, and a brief narrative description. The authors reviewed the narrative in the hair care products category and abstracted records indicating the injury was caused by contact with a curling iron. Also analyzed were the design features of commonly available curling irons purchased from national discount department stores. Results: There were an estimated 105,081 hair care product-related injuries in the five-year period, of which 82,151 (78%) involved a curling iron. Seventy percent of injuries were to females. The patient's median age was 8 years (range 1 month to 96 years). The most commonly occurring injury was thermal burns (97%; 79,912/82,151). Ninety-eight percent of the injuries occurred in the home and 99% of the patients were discharged home from the ED. In patients <4 years old, 56% of burns occurred by grabbing or touching, while in those ,10 years the burns occurred by contact while in use. In the older group 69% of burns were of the cornea. Most curling irons use small amounts of power, yet there are no standards for temperature settings or control. The cylinder containing the heating element is mostly exposed, and many irons do not have a power switch. Conclusions: The most common injury resulting from curling irons is thermal burns. The mechanisms and patterns of injury in developmentally distinct age groups suggest that many of these injuries could be prevented by public education and the re-engineering of curling irons. [source]

    Micromorphological evidence of black carbon in colluvial soils from NW Spain

    EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2008
    J. Kaal
    Summary Biomass burning produces a residue called black carbon (BC). Black C is generally considered to be highly resistant against biodegradation and has a potential role in the global C cycle, but is difficult to identify and quantify when subjected to prolonged degradation in terrestrial sediments. The colluvial soils from Campo Lameiro (NW Spain), also known as ,Atlantic rankers', are rich in organic matter (up to 140 g C kg,1 soil). A micromorphological study was undertaken to test the hypothesis that a large proportion of the organic matter was derived from BC formed during Holocene wildfires (up to > 6000 years ago). As roughly estimated from image analysis of 12 thin sections, the volumetric BC contribution ranged between 10 and 60% (26% on average) of the organic matter. This is a conservative estimate as additional morphologically unrecognizable BC was present in the microgranular matrix of coalesced excrement. We conclude that (i) currently unknown quantities of BC are stored in Atlantic rankers and (ii) analysis of thin sections is an effective tool to identify BC. [source]

    EFFECTIVE POPULATION SIZES AND TEMPORAL STABILITY OF GENETIC STRUCTURE IN RANA PIPIENS, THE NORTHERN LEOPARD FROG

    EVOLUTION, Issue 11 2004
    Eric A. Hoffman
    Abstract Although studies of population genetic structure are very common, whether genetic structure is stable over time has been assessed for very few taxa. The question of stability over time is particularly interesting for frogs because it is not clear to what extent frogs exist in dynamic metapopulations with frequent extinction and recolonization, or in stable patches at equilibrium between drift and gene flow. In this study we collected tissue samples from the same five populations of leopard frogs, Rana pipens, over a 22,30 year time interval (11,15 generations). Genetic structure among the populations was very stable, suggesting that these population were not undergoing frequent extinction and colonization. We also estimated the effective size of each population from the change in allele frequencies over time. There exist few estimates of effective size for frog populations, but the data available suggest that ranid frogs may have much larger ratios of effective size (Ne) to census size (Nc) that toads (bufonidae). Our results indicate that R. pipiens populations have effective sizes on the order of hundreds to at most a few thousand frogs, and Nee/Nc ratios in the range of 0.1,1.0. These estimates of Ne/Nc are consistent with those estimated for other Rana species. Finally, we compared the results of three temporal methods for estimating Ne. Moment and pseudolikelihood methods that assume a closed population gave the most similar point estimates, although the moment estimates were consistently two to four times larger. Wang and Whitlock's new method that jointly estimates Ne and the rate of immigration into a population (m) gave much smaller estimates of Ne and implausibly large estimates of m. This method requires knowing allele frequencies in the source of immigrants, but was thought to be insensitive to inexact estimates. In our case the method may have failed because we did not know the true source of immigrants for each population. The method may be more sensitive to choice of source frequencies than was previously appreciated, and so should be used with caution if the most likely source of immigrants cannot be identified clearly. [source]

    ENVIRONMENT-DEPENDENT ADMIXTURE DYNAMICS IN A TIGER SALAMANDER HYBRID ZONE

    EVOLUTION, Issue 6 2004
    Benjamin M. Fitzpatrick
    Abstract After an estimated five million years of independent evolution, the barred tiger salamander (Ambystoma tigrinum mavortium) was introduced by bait dealers into the native range of the California tiger salamander (A. californiense). Hybridization and backcrossing have been occurring in central California for 50,xs60 years, or an estimated 15,30 generations. We studied genetic and ecological factors influencing admixture of these two divergent gene pools by analyzing frequencies of hybrid genotypes in three kinds of breeding habitats: natural vernal pools, ephemeral man-made cattle ponds, and perennial man-made ponds. Perennial ponds tended to have higher frequencies of nonnative alleles than either type of seasonal pond, even in cases where perennial and seasonal ponds are within a few hundred meters. Thus, the hybrid zone has a mosaic structure that depends on pond hydrology or ecology. The presence of some broadly acting constraints on admixture is suggested by linkage disequilibria between physically unlinked molecular markers within ponds. In addition, we found several marker-specific deviations from Hardy-Weinberg equilibrium. One marker showed a consistent deficit of heterozygotes across pond types. Another showed heterozygote deficits only in vernal pools. A third was more likely to have heterozygote excess in ephemeral cattle ponds. These patterns indicate that admixture is influenced by complex genotype-by-environment interactions. [source]

    Tax Sensitivity in Electronic Commerce,

    FISCAL STUDIES, Issue 4 2007
    Mark A. Scanlan
    Empirical research into the impact of taxation on e-commerce has concluded that there is a significant positive relationship between local sales tax rates and the likelihood that a person will shop online. This paper finds that the tax sensitivity for online purchases at the local level is much lower than previously estimated and is not significant under previous general models. However, by using a splined tax-rate function, this paper finds that consumers living in counties with high sales tax rates are still sensitive to tax rates when deciding whether to shop online, while those in counties with low tax rates exhibit no significant sensitivity. [source]

    Interaction of an insecticide with larval density in pond-breeding salamanders (Ambystoma)

    FRESHWATER BIOLOGY, Issue 4 2005
    BRIAN S. METTS
    Summary 1. Amphibian populations residing in or near agricultural areas are often susceptible to pesticide contamination. Recent evidence suggests that the effects of pesticides on amphibians often exceed those estimated in laboratory toxicity tests because other environmental factors (e.g. predators, resource abundance) can influence pesticide toxicity. 2. To examine the effects of an insecticide (carbaryl) on two species of Ambystoma salamanders experiencing the natural stress of competition, we manipulated chemical concentration (control, 3.5 and 7.0 mg L,1) and larval density (low and high). We determined the effect of treatments on snout-vent length (SVL), growth rate, lipid reserves, time to metamorphosis, per cent survival and per cent metamorphosis. 3. Carbaryl negatively affected all response variables of Ambystoma maculatum significantly, and significantly reduced survival and metamorphosis of A. opacum. Increased density significantly influenced SVL, lipid reserves, growth rate and metamorphosis of A. maculatum. 4. The effects of carbaryl and increased density on per cent metamorphosis were nearly additive, but were generally less than additive on other variables. 5. The negative effects of chemical contamination on salamanders were likely because of pesticide-induced reductions of food resources, as zooplankton abundance decreased by as much as 97% following carbaryl application. 6. Our study demonstrates the importance of the interactive effects that chemical contamination and natural environmental factors have on salamanders. [source]

    Effects of fire on surface carbon, energy and water vapour fluxes over campo sujo savanna in central Brazil

    FUNCTIONAL ECOLOGY, Issue 6 2003
    A. J. B. Santos
    Summary 1Tower-based eddy covariance measurements were used to quantify the effect of fire on subsequent carbon dioxide fluxes and water and surface energy balance characteristics for campo sujo savanna located near Brasília in Central Brazil (15°56, S, 47°51, W). Campo sujo is a xeromorphic, open shrub savanna with very scattered but definitely visible shrubs and tree-like shrub elements. We studied two areas, one exposed to a prescribed fire late in the dry season, and a second that had not been burned for the previous 4 years. 2The fire on 22 September 1998 consumed an estimated 26 mol C m,2. Immediately after the fire, evapotranspiration rates decreased and the savanna became a stronger net source of CO2 to the atmosphere. This was attributed to the removal of the still slightly physiologically active grass layer and higher soil CO2 efflux rates as a consequence of elevated surface soil temperatures post-burning. 3On the commencement of the first rains in early October 1998, this situation was reversed, with the burned area rapidly becoming a stronger sink for CO2 and with higher evapotranspiration rates than a nearby unburned (control) area. This difference persisted throughout the wet season (until at least June 1999) and was attributable to greater physiological activity of the regrowing vegetation in the burned area. Early in the growing season, higher soil evaporation rates may also have contributed to faster water use by the previously burned area. 4Overall, we estimate an annual gross primary productivity for the burned area of 135 mol C m,2 year,1, with that for the unburned area being 106 mol C m,2 year,1. Estimated ecosystem respiration rates were more similar on an annual basis (96 and 82 mol C m,2 year,1 for the burned and unburned areas, respectively), giving rise to a substantially higher net ecosystem productivity for the previously burned area (38 vs 24 mol C m,2 year,1). 5Stimulation of photosynthetic activity in the rapid post-fire growth phase means that the negative effects of fire on the ecosystem carbon balance were more or less neutralized after only 12 months. [source]

    Late Quaternary landscape history and geoarchaeology of two drainages on Black Mesa, northeastern Arizona, USA

    GEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2005
    Eric T. Karlstrom
    Two approximately 5- to 6-km drainage segments on Black Mesa preserve unusually complete sequences of late Quaternary alluvium and soils. Radiocarbon- and tree-ring-dated alluvial and soil stratigraphy suggests entrenched paleoarroyos were beginning to aggrade at about >24,260, 11,070, 9660, 8800, 7060, 3500, 2140, and 1870 14C yr B.P. Using the quantity of sediment removal from post-A.D. 1900 arroyos as analogue, at least 77,200% of total valley alluvium has been removed and replaced by younger sediments during an estimated 11 late Pleistocene and Holocene erosion epicycles. Given that most (59%) of the 150 recorded prehistoric sites in the two study areas occur on valley floors where only about 3% of surface alluvium predates Lolomai phase Basketmaker II occupation (,1900,1600 yr B.P.), it may be inferred that pre-Lolomai phase Basketmaker II sites which may have been located along washes have been removed or buried by fluvial erosion. Identification of five buried hearths in alluvial sections, including White Dog and Lolomai phase Basketmaker II sites (dating about 3500 and 1870 14C yr B.P., respectively) and one possible Early Archaic site, supports this conclusion. © 2005 Wiley Periodicals, Inc. [source]

    BRAZILIAN IMMIGRATION TO THE UNITED STATES AND THE GEOGRAPHICAL IMAGINATION,

    GEOGRAPHICAL REVIEW, Issue 4 2009
    ALAN P. MARCUS
    ABSTRACT. In the late 1980s more than 1 million Brazilians left Brazil without returning. Today an estimated 2 million Brazilians live abroad, 1.2 million of them in the United States. In this article I show that Brazilians migrate for a variety of reasons, including the geographical imagination. Why are so many Brazilians leaving for the United States? What are their geographical imaginations, and how are they described in their migration process? Using primary and secondary data and multiple methods, I address these questions by providing insights into Brazilian migrants' place perceptions, experiences, and reasons for migrating, focusing on the geographical imagination. Those migrants who end up returning to Brazil are more likely to cite financial and curiosity reasons for having migrated. A web of transnational religious and social networks sustains those immigrants who remain in the United States. Reasons for migrating are not economic alone; rather, they are based on interrelated and complex factors that range from adventure to curiosity, the cultural influence of the United States, family members, education, and escape. [source]

    SNOWSHED CONTRIBUTIONS TO THE NOOKSACK RIVER WATERSHED, NORTH CASCADES RANGE, WASHINGTON,

    GEOGRAPHICAL REVIEW, Issue 2 2002
    ANDREW BACH
    ABSTRACT. Meltwater contributes to watershed hydrology by increasing summer discharge, delaying the peak spring runoff, and decreasing variability in runoff. High-elevation snowshed meltwater, including glacier-derived input, provides an estimated 26.9 percent of summer streamflow (ranging annually from 16 to 40 percent) in the Nooksack River Basin above the town of Deming, Washington, in the North Cascades Range. The Nooksack is a major spawning river for salmon and once was important for commercial, recreational, and tribal fishing, and in the past its flow met the demands of both human and aquatic ecosystems. But the river is already legally overallocated, and demand is rising in response to the rapidly growing human population. Variability in snowshed contributions to the watershed is considerable but has increased from an average of 25.2 percent in the 1940s to an average of 30.8 percent in the 1990s. Overall stream discharge shows no significant increase, suggesting that the glaciers are melting, and/or precipitation levels (or other hydrologic factors) are decreasing at about the same rate. If glaciers continue to recede, they may disappear permanently from the Cascades. If that occurs, their summer contribution to surface-water supplies will cease, and water-management policies will need drastic revision. [source]

    Separation of intrinsic and scattering seismic attenuation in the Southern Apennine zone, Italy

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002
    F. Bianco
    Summary Scattered waves observed at the seismographs of the National Italy's seismic network have been used to investigate the intrinsic dissipation and scattering properties of the lithosphere under the Southern Apennines, Italy. First, we investigate the coda-Q properties, then we apply the MLTW analysis in the hypothesis of velocity and scattering coefficient constant with depth, and finally we interpret these results with the aid of numerical simulations in a medium with depth dependent velocity and scattering coefficient. Results obtained in the hypothesis of a uniform model show that a low scattering-Q,1 and a relatively higher intrinsic-Q,1 characterize the lithosphere of the Southern Apennines. Numerical simulations of the seismogram energy envelopes were performed hypothesizing a strongly scattering crust and trasparent upper mantle, both with reasonable intrinsic dissipation coefficients. In these symplifying assumptions the theoretical curves calculated for the homogeneous model fit to the synthetic envelopes with scattering attenuation coefficients always greater than the synthetic values. This results lead to the consideration that scattering-Q,1 obtained using MLTW analysis under the assumption of uniform medium are overestimated. The values of the scattering-Q,1 estimated for Apennines at low frequency (1,2 Hz) in the hypothesis of uniform medium are of the same order of those obtained in several areas around the world. The estimates obtained for frequencies ranging from 2 to 12 Hz are very low if compared with those obtained in the same hypothesis for other areas around the world. Coda Q,1 closely resembles intrinsic Q,1. [source]

    Accumulation of carbon and nitrogen by old arable land reverting to woodland

    GLOBAL CHANGE BIOLOGY, Issue 6 2003
    P. R. POULTON
    Abstract The accumulation of carbon (C) and nitrogen (N) was measured on two sites on Rothamsted Farm that had been fenced off some 120 years ago and allowed to revert naturally to woodland. The sites had previously been arable for centuries. One had been chalked and was still calcareous; the other had never been chalked and the pH fell from 7.1 in 1883 to 4.4 in 1999. The acidic site (Geescroft wilderness) is now a deciduous wood, dominated by oak (Quercus robor); the calcareous site (Broadbalk wilderness) is now dominated by ash (Fraxinus excelsior), with sycamore (Acer pseudoplatanus) and hawthorn (Craetagus monogyna) as major contributors. The acidic site gained 2.00 t C ha,1 yr,1 over the 118-year period (0.38 t in litter and soil to a depth of 69 cm, plus an estimated 1.62 t in trees and their roots); the corresponding gains of N were 22.2 kg N ha,1 year,1 (15.2 kg in the soil, plus 6.9 kg in trees and their roots). The calcareous site gained 3.39 t C ha,1 year,1 over the 120-year period (0.54 t in the soil, plus an estimated 2.85 t in trees and roots); for N the gains were 49.6 kg ha,1 yr,1 (36.8 kg in the soil, plus 12.8 kg in trees and roots). Trees have not been allowed to grow on an adjacent part of the calcareous site. There is now a little more C and N in the soil from this part than in the corresponding soil under woodland. We argue from our results that N was the primary factor limiting plant growth and hence accumulation of C during the early stages of regeneration in these woodlands. As soil organic N accumulates and the sites move towards N saturation, other factors become limiting. Per unit area of woodland, narrow strips; that is, wide hedges with trees, are the most efficient way of sequestering C , provided that they are not short of N. [source]

    Heat transfer of combined forced and natural convection from horizontal cylinder to air

    HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2007
    Kenzo Kitamura
    Abstract Experimental investigations have been carried out for combined convective flows of air induced around uniformly heated, horizontal cylinders. Three cases of aiding, opposing, and cross flows were examined. The experiments covered the ranges of the Reynolds and modified Rayleigh numbers of Red=50 to 900 and Rad*=5×104 to 3×106. The flow fields around the cylinders were visualized with smoke. The results showed that separation points gradually shift from those of the forced convection to the top edge of the cylinder with increasing wall heat fluxes. The local heat transfer coefficients of the cylinders were also measured. Although the local coefficients show complex variations with the forced flow velocities and the wall heat fluxes, the overall coefficients become higher than those estimated from pure forced and natural convections throughout the cases of aiding, opposing, and cross flows. Moreover, it was confirmed that the overall Nusselt numbers as well as the separation points can be predicted with the non-dimensional parameter (Grd*/NudRed2). © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 474,488, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20180 [source]

    Age at Acquisition of Helicobacter pylori in a Pediatric Canadian First Nations Population

    HELICOBACTER, Issue 2 2002
    Samir K. Sinha
    Abstract Background. Few data exist regarding the epidem-iology of Helicobacter pylori infections in aboriginal, including the First Nations (Indian) or Inuit (Eskimo) populations of North America. We have previously found 95% of the adults in Wasagamack, a First Nations community in Northeastern Manitoba, Canada, are seropositive for H. pylori. We aimed to determine the age at acquisition of H. pylori among the children of this community, and if any association existed with stool occult blood or demographic factors. Materials and Methods. We prospectively enrolled children resident in the Wasagamack First Nation in August 1999. A demographic questionnaire was administered. Stool was collected, frozen and batch analyzed by enzyme-linked immunosorbent assay (ELISA) for H. pylori antigen and for the presence of occult blood. Questionnaire data were analyzed and correlated with the presence or absence of H. pylori. Results. 163 (47%) of the estimated 350 children aged 6 weeks to 12 years, resident in the community were enrolled. Stool was positive for H. pylori in 92 (56%). By the second year of life 67% were positive for H. pylori. The youngest to test positive was 6 weeks old. There was no correlation of a positive H. pylori status with gender, presence of pets, serum Hgb, or stool occult blood. Forty-three percent of H. pylori positive and 24% of H. pylori negative children were < 50th percentile for height (p = 0.024). Positive H. pylori status was associated with the use of indoor pail toileting (86/143) compared with outhouse toileting (6/20) (p = 0.01). Conclusions. In a community with widespread H. pylori infection, overcrowded housing and primitive toileting, H. pylori is acquired as early as 6 weeks of age, and by the second year of life 67% of children test positive for H. pylori. [source]

    Surprises from the crystal structure of the hepatitis C virus NS2-3 protease,

    HEPATOLOGY, Issue 6 2006
    Jerome Gouttenoire Ph.D.
    Hepatitis C virus is a major global health problem affecting an estimated 170 million people worldwide. Chronic infection is common and can lead to cirrhosis and liver cancer. There is no vaccine available and current therapies have met with limited success. The viral RNA genome encodes a polyprotein that includes 2 proteases essential for virus replication. The NS2-3 protease mediates a single cleavage at the NS2/NS3 junction, whereas the NS3-4A protease cleaves at 4 downstream sites in the polyprotein. NS3-4A is characterized as a serine protease with a chymotrypsin-like fold, but the enzymatic mechanism of the NS2-3 protease remains unresolved. Here, we report the crystal structure of the catalytic domain of the NS2-3 protease at 2.3 Å resolution. The structure reveals a dimeric cysteine protease with 2 composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer, and the nucleophilic cysteine by the other. The carboxy-terminal residues remain coordinated in the 2 active sites, predicting an inactive postcleavage form. Proteolysis through formation of a composite active site occurs in the context of the viral polyprotein expressed in mammalian cells. These features offer unexpected insights into polyprotein processing by hepatitis C virus and new opportunities for antiviral drug design. [source]