983 resultados para International publication ratio


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The research leading to these results has received funding from the European Union's Seventh Framework Programme (KBBE.2013.1.2-10) under grant agreement n° 613611 FISHBOOST. Moreover, the original data collection was supported by the European Union, Project PROGRESS Q5RS-2001-00994. The staff at Tervo station, Ossi Ritola and Tuija Paananen, are highly acknowledged for fish management. A. Ka., A. Ki., S. M., D. H. and K. R. designed research and wrote the paper; A.Ka analyzed the data and had primary responsibility for the final content. All authors have read and approved the manuscript. The authors declare no conflicts of interest.

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Phytoplankton are the basis of marine food webs, and affect biogeochemical cycles. As CO2 levels increase, shifts in the frequencies and physiology of ecotypes within phytoplankton groups will affect their nutritional value and biogeochemical function. However, studies so far are based on a few representative genotypes from key species. Here, we measure changes in cellular function and growth rate at atmospheric CO2 concentrations predicted for the year 2100 in 16 ecotypes of the marine picoplankton Ostreococcus. We find that variation in plastic responses among ecotypes is on par with published between-genera variation, so the responses of one or a few ecotypes cannot estimate changes to the physiology or composition of a species under CO2 enrichment. We show that ecotypes best at taking advantage of CO2 enrichment by changing their photosynthesis rates most should increase in relative fitness, and so in frequency in a high-CO2 environment. Finally, information on sampling location, and not phylogenetic relatedness, is a good predictor of ecotypes likely to increase in frequency in this system.

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This dissertation examines the drivers and implications of international capital flows. The overarching motivation is the observation that countries not at the centre of global financial markets are subject to considerable spillovers from centre countries, notably from their monetary policy. I present new empirical evidence on the determinants of the observed patterns of international capital flows and monetary policy spillovers, and study their effect on both financial markets and the real economy. In Chapter 2 I provide evidence on the determinants of a puzzling negative correlation observed between productivity growth and net capital inflows to developing and emerging market economies (EMEs) since 1980. By disaggregating net capital inflows into their gross components, I show that this negative correlation is explained by capital outflows related to purchases of very liquid assets from the fastest growing countries. My results suggest a desire for international portfolio diversification in liquid assets by fast growing countries is driving much of the original puzzle. In the reminder of my dissertation I pivot to study the foreign characteristics that drive international capital flows and monetary policy spillovers, with a particular focus on the role of unconventional monetary policy in the United States (U.S.). In Chapter 3 I show that a significant portion of the heterogeneity in EMEs' asset price adjustment following the quantitative easing operations by the Federal Reserve (the Fed) during 2008-2014 can be explained by the degree of bilateral capital market frictions between these countries and the U.S. This is true even after accounting for capital controls, exchange rate regimes, and domestic monetary policies. Chapter 4, co-authored with Michal Ksawery Popiel, studies unconventional monetary policy in a small open economy, looking specifically at the case of Canada since the global financial crisis. We quantify the effect Canadian unconventional monetary policy shocks had on the real economy, while carefully controlling for and quantifying spillovers from U.S. unconventional monetary policy. Our results indicate that the Bank of Canada's unconventional monetary policy increased Canadian output significantly from 2009-2010, but that spillovers from the Fed's policy were even more important for increasing Canadian output after 2008.

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The use of nanoparticle technology in consumer products has been increasing due to their broad-spectrum antimicrobial properties. Specifically, silver nanoparticles (AgNPs) can demonstrate distinct physiochemical properties compared to bulk silver, including a large surface area to volume ratio that allows for higher reactivity with bacterial cell surfaces. AgNPs are being released into the environment, including soil ecosystems through various pathways such as points of production or during disposal of silver-containing products. This raises the concern about the potential impact on beneficial soil bacteria and their surrounding ecosystems. Members of the Rhizobiaceae family play important roles in nutrient cycling and contribute to overall soil fertility and the experiments in this thesis address the potential for AgNP-mediated toxicity on these plant-associating bacteria. Respiration analysis of Bradyrhizobium japonicum, Azospirillum brasilense, and Agrobacterium tumefaciens has revealed that AgNPs can negatively impact the growth and survival of these bacterial species, with B. japonicum being the most susceptible. Additionally, swimming motility assays using B. japonicum showed a significant decrease in colony diameter when treated with AgNPs (50 ppm). A significant decrease in root colonization of Triticum aestivum roots by A. brasilense was observed as AgNP treatment concentrations increased. Although some of the experiments could not be completed, taken together, these experiments and the research reported herein highlights the potential toxicological effects of AgNPs on bacterial species vital to the growth and health of agriculturally important crops.

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Background: Individuals with chronic obstructive pulmonary disease (COPD) have higher than normal ventilatory equivalents for carbon dioxide (VE/VCO2) during exercise. There is growing evidence that emphysema on thoracic computed tomography (CT) scans is associated with poor exercise capacity in COPD patients with only mild-to-moderate airflow obstruction. We hypothesized that emphysema is an underlying cause of microvascular dysfunction and ventilatory inefficiency, which in turn contributes to reduced exercise capacity. We expected ventilatory inefficiency to be associated with a) the extent of emphysema; b) lower diffusing capacity for carbon monoxide; c) a reduced pulmonary blood flow response to exercise; and d) reduced exercise capacity. Methods: In a cross-sectional study, 19 subjects with mild-to-moderate COPD (mean ± SD FEV1= 82 ± 13% predicted, 12 GOLD grade 1) and 26 age-, sex-, and activity-matched controls underwent a ramp-incremental symptom-limited exercise test on a cycle ergometer. Ventilatory inefficiency was assessed by the minimum VE/VCO2 value (nadir). A subset of subjects also completed repeated constant work rate exercise bouts with non-invasive measurements of pulmonary blood flow. Emphysema was quantified as the percentage of attenuation areas below -950 Housefield Units on CT scans. An electronic scoresheet was used to keep track of emphysema sub-types. Results: COPD subjects typically had centrilobular emphysema (76.8 ± 10.1% of total emphysema) in the upper lobes (upper/lower lobe ratio= 0.82 ± 0.04). They had lower peak oxygen uptake (VO2), higher VE/VCO2 nadir and greater dyspnea scores than controls (p<0.05). Lower peak O2 and worse dyspnea were found in COPD subjects with VE/VCO2 nadirs ≥ 30. COPD subjects had blunted increases in pulmonary blood flow from rest to iso-VO2 exercise (p<0.05). Higher VE/VCO2 nadir in COPD subjects correlated with emphysema severity (r= 0.63), which in turn correlated with reduced lung diffusing capacity (r= -0.72) and blunted changes in pulmonary blood flow from rest to exercise (r= -0.69) (p<0.01). Conclusions: Ventilation “wasted” in emphysematous areas is associated with reduced exercise ventilatory efficiency in mild-to-moderate COPD. Exercise ventilatory inefficiency links structure (emphysema) and function (gas transfer) to a key clinical outcome (reduced exercise capacity) in COPD patients with modest spirometric abnormalities.

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Background: As the global population is ageing, studying cognitive impairments including dementia, one of the leading causes of disability in old age worldwide, is of fundamental importance to public health. As a major transition in older age, a focus on the complex impacts of the duration, timing, and voluntariness of retirement on health is important for policy changes in the future. Longer retirement periods, as well as leaving the workforce early, have been associated with poorer health, including reduced cognitive functioning. These associations are hypothesized to differ based on gender, as well as on pre-retirement educational and occupational experiences, and on post-retirement social factors and health conditions. Methods: A cross-sectional study is conducted to determine the relationship between duration and timing of retirement and cognitive function, using data from the five sites of International Mobility in Aging Study (IMIAS). Cognitive function is assessed using the Leganes Cognitive Test (LCT) scores in 2012. Data are analyzed using multiple linear regressions. Analyses are also done by site/region separately (Canada, Latin America, and Albania). Robustness checks are done with an analysis of cognitive change from 2012 to 2014, the effect of voluntariness of retirement on cognitive function. An instrumental variable (IV) approach is also applied to the cross-sectional and longitudinal analyses as a robustness check to address the potential endogeneity of the retirement variable. Results: Descriptive statistics highlight differences between men and women, as well as between sites. In linear regression analysis, there was no relationship between timing or duration of retirement and cognitive function in 2012, when adjusting for site/region. There was no association between retirement characteristics and cognitive function in site/region/stratified analyses. In IV analysis, longer retirement and on time or late retirement was associated with lower cognitive function among men. In IV analysis, there is no relationship between retirement characteristics and cognitive function among women. Conclusions: While results of the thesis suggest a negative effect of retirement on cognitive function, especially among men, the relationship remains uncertain. A lack of power results in the inability to draw conclusions for site/region-specific analysis and site-adjusted analysis in both linear and IV regressions.

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The first objective of this research was to develop closed-form and numerical probabilistic methods of analysis that can be applied to otherwise conventional methods of unreinforced and geosynthetic reinforced slopes and walls. These probabilistic methods explicitly include random variability of soil and reinforcement, spatial variability of the soil, and cross-correlation between soil input parameters on probability of failure. The quantitative impact of simultaneously considering the influence of random and/or spatial variability in soil properties in combination with cross-correlation in soil properties is investigated for the first time in the research literature. Depending on the magnitude of these statistical descriptors, margins of safety based on conventional notions of safety may be very different from margins of safety expressed in terms of probability of failure (or reliability index). The thesis work also shows that intuitive notions of margin of safety using conventional factor of safety and probability of failure can be brought into alignment when cross-correlation between soil properties is considered in a rigorous manner. The second objective of this thesis work was to develop a general closed-form solution to compute the true probability of failure (or reliability index) of a simple linear limit state function with one load term and one resistance term expressed first in general probabilistic terms and then migrated to a LRFD format for the purpose of LRFD calibration. The formulation considers contributions to probability of failure due to model type, uncertainty in bias values, bias dependencies, uncertainty in estimates of nominal values for correlated and uncorrelated load and resistance terms, and average margin of safety expressed as the operational factor of safety (OFS). Bias is defined as the ratio of measured to predicted value. Parametric analyses were carried out to show that ignoring possible correlations between random variables can lead to conservative (safe) values of resistance factor in some cases and in other cases to non-conservative (unsafe) values. Example LRFD calibrations were carried out using different load and resistance models for the pullout internal stability limit state of steel strip and geosynthetic reinforced soil walls together with matching bias data reported in the literature.

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Preeclampsia (PE) is a pregnancy complication that is new-onset of hypertension and proteinuria after 20 weeks of gestation. However, subclinical renal dysfunction may be apparent earlier in gestation prior to the clinical presentation of PE. Although the maternal syndrome of PE resolves early postpartum, women with a history of PE are at higher risk of renal dysfunction later in life. Mineral metabolism, such as phosphate balance is heavily dependent on renal function, yet, phosphate handling in women with a history of PE is largely unknown. To investigate whether women with a history of PE would exhibit changes in phosphate metabolism compared to healthy parous women, phosphate loading test was used. Women with or without a history of PE, who were 6 months to 5 years postpartum, were recruited for this study. Blood and urine samples were collected before and after the oral dosing of 500mg phosphate solution. Biochemical markers of phosphate metabolism and renal function were evaluated. In order to assess the difference in renal function alteration between first trimester women who were or were not destined to develop PE, plasma cystatin C concentration was analysed. After phosphate loading, women with a history of PE had significantly elevated serum phosphate at both 1- and 2-hour, while controls had higher urine phosphate:urine creatinine excretion ratio at 1-hour than women with a history of PE. Women with a history of PE had no changes in intact parathyroid hormone (iPTH) concentration throughout the study period, whereas controls had elevated iPTH at 1-hour from baseline. In terms of renal function in the first trimester, there was no difference in plasma cystatin C concentration between women who were or were not destined to develop PE. The elevation of serum phosphate in women with a history of PE could be due to the delay in phosphate excretion. Prolong elevation of serum phosphate can have serious consequences later in life. Thus, oral phosphate challenge may serve as a useful method of early screening for altered phosphate metabolism and renal function.

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The thesis focuses on a central theme of the epidemiology and health economics of ankle sprains to inform health policy and the provision of health services. It describes the burden, prognosis, resource utilization, and costs attributed to these injuries. The first manuscript systematically reviewed 34 studies on the direct and indirect costs of treating ankle and foot injuries. The overall costs per patient ranged from $2,075- $3,799 (2014 USD) for ankle sprains; $290-$20,132 for ankle fractures; and $6,345-$45,731 for foot fractures, reflecting differences in injury severity, treatment methods, and study characteristics. The second manuscript provided an epidemiological and economic profile of non-fracture ankle and foot injuries in Ontario using linked databases from the Institute for Clinical Evaluative Sciences. The incidence rate of ankle sprains was 16.9/1,000 person-years. Annually, ankle and foot injuries cost $21,685,876 (2015 CAD). The mean expenses per case were $99.98 (95% CI, $99.70-100.26) for any injury. Costs ranged from $133.78-$210.75 for ankle sprains and $1,497.12-$1,755.69 for dislocations. The third manuscript explored the impact of body mass index on recovery from medically attended grade 1 and 2 ankle sprains using the Foot and Ankle Outcome Score. Data came from a randomized controlled trial of a physiotherapy intervention in Kingston, Ontario. At six months, the odds ratio of recovery for participants with obesity was 0.60 (0.37-0.97) before adjustment and 0.74 (0.43-1.29) after adjustment compared to non-overweight participants. The fourth manuscript used trial data to examine the health-related quality of life among ankle sprain patients using the Health Utilities Index version 3 (HUI-3). The greatest improvements in scores were seen at one month post-injury (HUI-3: 0.88, 95% CI: 0.86-0.90). Individuals with grade 2 sprains had significantly lower ambulation scores than those with grade 1 sprains (0.70 vs. 0.84; p<0.05). The final manuscript used trial data to describe the financial burden (direct and indirect costs) of ankle sprains. The overall mean costs were $1,508 (SD: $1,452) at one month and increased to $2,206 (SD: $3,419) at six months. Individuals with more severe injuries at baseline had significantly higher (p<0.001) costs compared to individuals with less severe injuries, after controlling for confounders.

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The problem of decentralized sequential detection is studied in this thesis, where local sensors are memoryless, receive independent observations, and no feedback from the fusion center. In addition to traditional criteria of detection delay and error probability, we introduce a new constraint: the number of communications between local sensors and the fusion center. This metric is able to reflect both the cost of establishing communication links as well as overall energy consumption over time. A new formulation for communication-efficient decentralized sequential detection is proposed where the overall detection delay is minimized with constraints on both error probabilities and the communication cost. Two types of problems are investigated based on the communication-efficient formulation: decentralized hypothesis testing and decentralized change detection. In the former case, an asymptotically person-by-person optimum detection framework is developed, where the fusion center performs a sequential probability ratio test based on dependent observations. The proposed algorithm utilizes not only reported statistics from local sensors, but also the reporting times. The asymptotically relative efficiency of proposed algorithm with respect to the centralized strategy is expressed in closed form. When the probabilities of false alarm and missed detection are close to one another, a reduced-complexity algorithm is proposed based on a Poisson arrival approximation. In addition, decentralized change detection with a communication cost constraint is also investigated. A person-by-person optimum change detection algorithm is proposed, where transmissions of sensing reports are modeled as a Poisson process. The optimum threshold value is obtained through dynamic programming. An alternative method with a simpler fusion rule is also proposed, where the threshold values in the algorithm are determined by a combination of sequential detection analysis and constrained optimization. In both decentralized hypothesis testing and change detection problems, tradeoffs in parameter choices are investigated through Monte Carlo simulations.

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Previous studies about the strength of the lithosphere in the Iberia centre fail to resolve the depth of earthquakes because of the rheological uncertainties. Therefore, new contributions are considered (the crustal structure from a density model) and several parameters (tectonic regime, mantle rheology, strain rate) are checked in this paper to properly examine the role of lithospheric strength in the intraplate seismicity and the Cenozoic evolution. The strength distribution with depth, the integrated strength, the effective elastic thickness and the seismogenic thickness have been calculated by a finite element modelling of the lithosphere across the Central System mountain range and the bordering Duero and Madrid sedimentary basins. Only a dry mantle under strike-slip/extension and a strain rate of 10-15 s-1, or under extension and 10-16 s-1, causes a strong lithosphere. The integrated strength and the elastic thickness are lower in the mountain chain than in the basins. These anisotropies have been maintained since the Cenozoic and determine the mountain uplift and the biharmonic folding of the Iberian lithosphere during the Alpine deformations. The seismogenic thickness bounds the seismic activity in the upper–middle crust, and the decreasing crustal strength from the Duero Basin towards the Madrid Basin is related to a parallel increase in Plio–Quaternary deformations and seismicity. However, elasto–plastic modelling shows that current African–Eurasian convergence is resolved elastically or ductilely, which accounts for the low seismicity recorded in this region.

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Mineral and chemical composition of alluvial Upper-Pleistocene deposits from the Alto Guadalquivir Basin (SE Spain) were studied as a tool to identify sedimentary and geomorphological processes controlling its formation. Sediments located upstream, in the north-eastern sector of the basin, are rich in dolomite, illite, MgO and KB2BO. Downstream, sediments at the sequence base are enriched in calcite, smectite and CaO, whereas the upper sediments have similar features to those from upstream. Elevated rare-earth elements (REE) values can be related to low carbonate content in the sediments and the increase of silicate material produced and concentrated during soil formation processes in the neighbouring source areas. Two mineralogical and geochemical signatures related to different sediment source areas were identified. Basal levels were deposited during a predominantly erosive initial stage, and are mainly composed of calcite and smectite materials enriched in REE coming from Neogene marls and limestones. Then the deposition of the upper levels of the alluvial sequences, made of dolomite and illitic materials depleted in REE coming from the surrounding Sierra de Cazorla area took place during a less erosive later stage of the fluvial system. Such modification was responsible of the change in the mineralogical and geochemical composition of the alluvial sediments.

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Students reflect more on their learning in course subjects when they participate in managing their teaching–learning environment. As a form of guided participation, peer assessment serves the following purposes: (a) it improves the student’s understanding of previously established learning objectives; (b) it is a powerful metacognitive tool; (c) it transfers to the student part of the responsibility for assessing learning, which means deciding which learning activities are important and choosing the degree of effort a course subject will require; (d) it emphasizes the collective aspect of the nature of knowledge; and (e) the educational benefits derived from peer assessment clearly justify the efforts required to implement activities. This paper reports on the relative merits of a learning portfolio compiled during fine arts-related studies in which peer assessment played an important role. The researchers analyzed the student work load and the final marks students received for compulsory art subjects. They conclude that the use of a closed learning portfolio with a well-structured, sequential and analytical design can have a positive effect on student learning and that, although implementing peer assessment may be complex and students need to become familiar with it, its use is not only feasible but recommendable.