805 resultados para GRANGER CAUSALITY


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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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Southwestern Africa's coastal marine mudbelt, a prominent Holocene sediment package, provides a valuable archive for reconstructing terrestrial palaeoclimates on the adjacent continent. While the origin of terrestrial inorganic material has been intensively studied, the sources of terrigenous organic material deposited in the mudbelt are yet unclear. In this study, plant wax derived n-alkanes and their compound-specific d13C in soils, flood deposits and suspension loads from regional fluvial systems and marine sediments are analysed to characterize the origin of terrestrial organic material in the southwest African mudbelt. Soils from different biomes in the catchments of the Orange River and small west coast rivers show on average distinct n-alkane distributions and compound-specific d13C values reflecting biome-specific vegetation types, most notably the winter rainfall associated Fynbos Biome of the southwestern Cape. In the fluvial sediment samples from the Orange River, changes in the n-alkane distributions and compound-specific d13C compositions reveal an overprint by local vegetation along the river's course. The smaller west coast rivers show distinct signals, reflecting their small catchment areas and particular vegetation communities. Marine surface sediments spanning a transect from the northern mudbelt (29°S) to St. Helena Bay (33°S) reveal subtle, but spatially coherent, changes in n-alkane distributions and compound-specific d13C, indicating the influence of Orange River sediments in the northern mudbelt, the increasing importance of terrigenous input from the adjacent western coastal biomes in the central mudbelt, and contributions from the Fynbos Biome to the southern mudbelt. These findings indicate the different sources of terrestrial organic material deposited in the mudbelt, and highlight the potential the mudbelt has to preserve evidence of environmental change from the adjacent continent.

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This thesis uses models of firm-heterogeneity to complete empirical analyses in economic history and agricultural economics. In Chapter 2, a theoretical model of firm heterogeneity is used to derive a statistic that summarizes the welfare gains from the introduction of a new technology. The empirical application considers the use of mechanical steam power in the Canadian manufacturing sector during the late nineteenth century. I exploit exogenous variation in geography to estimate several parameters of the model. My results indicate that the use of steam power resulted in a 15.1 percent increase in firm-level productivity and a 3.0-5.2 percent increase in aggregate welfare. Chapter 3 considers various policy alternatives to price ceiling legislation in the market for production quotas in the dairy farming sector in Quebec. I develop a dynamic model of the demand for quotas with farmers that are heterogeneous in their marginal cost of milk production. The econometric analysis uses farm-level data and estimates a parameter of the theoretical model that is required for the counterfactual experiments. The results indicate that the price of quotas could be reduced to the ceiling price through a 4.16 percent expansion of the aggregate supply of quotas, or through moderate trade liberalization of Canadian dairy products. In Chapter 4, I study the relationship between farm-level productivity and participation in the Commercial Export Milk (CEM) program. I use a difference-in-difference research design with inverse propensity weights to test for causality between participation in the CEM program and total factor productivity (TFP). I find a positive correlation between participation in the CEM program and TFP, however I find no statistically significant evidence that the CEM program affected TFP.

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The study examines the short-run and long-run causality running from real economic growth to real foreign direct investment inflows (RFDI). Other variables such as education (involving combination of primary, secondary and tertiary enrolment as a proxy to education), real development finance, unskilled labour, to real RFDI inflows are included in the study. The time series data covering the period of 1983 -2013 are examined. First, I applied Augmented Dicky-Fuller (ADF) technique to test for unit root in variables. Findings shows all variables integrated of order one [I(1)]. Thereafter, Johansen Co-integration Test (JCT) was conducted to establish the relationship among variables. Both trace and maximum Eigen value at 5% level of significance indicate 3 co-integrated equations. Vector error correction method (VECM) was applied to capture short and long-run causality running from education, economic growth, real development finance, and unskilled labour to real foreign direct investment inflows in the Republic of Rwanda. Findings shows no short-run causality running from education, real development finance, real GDP and unskilled labour to real FDI inflows, however there were existence of long-run causality. This can be interpreted that, in the short-run; education, development finance, finance and economic growth does not influence inflows of foreign direct investment in Rwanda; but it does in long-run. From the policy perspective, the Republic of Rwanda should focus more on long term goal of investing in education to improve human capital, undertake policy reforms that promotes economic growth, in addition to promoting good governance to attract development finance – especially from Nordics countries (particularly Norway and Denmark).

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Introduction - Nutritional therapy (NT) is a bioscience-based branch of complementary and alternative medicine (CAM) with National Occupational Standards (NOS) and accredited training courses which include compulsory clinical training. Approximately 900 practitioners are registered with the voluntary regulator, the Complementary and Natural Healthcare Council (CNHC), but the number of unregulated practitioners is unknown. Cancer is a leading cause of death worldwide; nutrition and lifestyle factors may affect recurrence and survival rates. Many cancer patients and survivors seek individualised advice on diet and use of supplements and appropriately skilled nutritional therapy practitioners (NTP) may be well-placed to safely provide this advice. Little is known of NTPs’ perspectives on working with people affected by cancer; this study seeks to explore their views on training, use of evidence and other resources, to support the development of safe evidence-based practice in this important clinical area. Methods – An on-line anonymised questionnaire collected data from participants recruited from all UK registered NTPs. Recruitment was facilitated by the British Association for Applied Nutrition and Nutritional Therapy (BANT). Quantitative data on practitioner characteristics, years in practice, other therapies practiced and work with cancer clients were collected. Qualitative data on types of evidence used, barriers to practice and perceived training and support needs when working with clients with cancer, were collected and analysed. SPSS was used to produce descriptive statistics. Preliminary Results – 274/888 (31%) of registered NTPs participated. 61% respondents had accredited NT qualifications of which 46% were at degree or post-graduate level. 73% (202) participants indicated they also had other higher education qualifications, including 153 (56%) at degree or above. When asked to describe their position on cancer work, 17% respondents (40/238) indicated no interest, and 35% (84/238) respondents already work with cancer clients (cancer practitioners - CP). A further 48% (114/238) respondents expressed interest in starting cancer work, and typically requested specialist training and practice guidelines to support this area of clinical practice. Cancer practitioners (CP) rated searches of peer-reviewed literature as most useful for information to support practice, whereas commercial product information was rated least useful. CPs requested engagement with mainstream medicine, more access to research evidence and professional recognition to facilitate and support work with cancer clients. A need for professional networking, mentorship and/or supervision was noted by CP and non-CP respondents, which is of interest since 81% all participants worked as sole practitioners exclusively or as part of their practice, <1% worked within the NHS. Discussion & Conclusions – This is the first detailed documentation of NTP perspectives on cancer work. A number of areas have been identified for further detailed evidence to be collected using focus groups and interviews, including detailed training needs, communication with mainstream cancer professionals, access to research evidence, and professional recognition. This work will inform and support the development of professional practice guidelines for NT and inform the development of specialist training and other resources.

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Introduction: Cancer is a leading cause of death worldwide. Nutrition may affect occurrence, recurrence and survival rates and many cancer patients and survivors seek individualized nutrition advice. Appropriately skilled nutritional therapy (NT) practitioners may be well-placed to safely provide this advice, but little is known of their perspectives on working with people affected by cancer. This mixed-methods study seeks to explore their views on training, barriers to practice, use of evidence, and other resources, to support the development of safe evidence-based practice. Preliminary data on barriers to practice are reported here. Methods: Two cohorts of NT practitioners were recruited from all UK registered NT practitioners, by an on-line anonymous survey. 84 cancer practitioners (CP) and 165 non-cancer practitioners (NCP) were recruited. Mixed quantitative and qualitative data was collected by the survey. Content analysis was used to analyze qualitative data on the use of evidence, barriers to practice and perceived needs for working with clients with cancer, for further exploration using interviews and focus groups. Preliminary results: For the NCP cohort, exploring themes of perceived barriers to working with people affected by cancer suggested that perceived complexity, risk and need for caution in this area of practice were important barriers. Insufficient specialist knowledge and skills also emerged as barriers. Some NCPs perceived opposition from medical practitioners and other mainstream healthcare professions as an obstacle to starting cancer practice. To overcome these barriers, specialist training emerged as most important. For the CP cohort, in exploring the skills they considered enabled them to undertake cancer work, specialist clinical and technical knowledge emerged strongly. Only 10% CP participants did not want more work with people affected by cancer. 10% CPs reported some NHS referrals, whereas most received clients by self-referral or from other practitioners. When considering barriers that impede their cancer practice, the dominant categories for CPs were hostility or opposition by mainstream oncology professionals, and lack of dialogue and engagement with them. To overcome these barriers, CPs desired engagement with oncology professionals and recognized specialist cancer NT training. For both NCPs and CPs, evidence resources, practice guidelines and practitioner support networks also emerged as potential enablers to cancer practice. Conclusions: This is the first detailed exploration of NT practitioners’ perceived barriers to working with people affected by cancer. Acquiring specialist skills and knowledge appears important to enable NCPs to start cancer work, and for CPs with these skills, the perceived barriers appear foremost in the relationship with mainstream cancer professionals. Further exploration of these themes, and other NT practitioner perspectives on working with people affected by cancer, is underway. This work will inform and support the development of professional practice, training and other resources.

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Organizations of the Social Economy in Spain accounted for 13% of employment and 12% of GDP in 2013, according to the Spanish Confederation fo Social Economy. Also, according to various institutions and studies, the role of Social Economy has become relevant due to they represent a model promoting the creation of collective business projects with greater sustainability and potential than models of individual self-employment. However, despite all this, there are few academic studies or sectoral reports analyzing employment in this sector, especially in the case of youth employment. This study aims to fill this gap in the literature analyzing the scared available data in order to show the numbers and characteristics of youth employment in this sector. Results show the weight of youth employment in the Social Economy is higher than the economy overall.

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En este trabajo se presenta la concepción aristotélica de la filosofía primera como ciencia de los principios y de las causas primeras según el libro primero de la Metafísica. Para ello, se distinguen tres momentos sucesivos que constituyen el análisis de la naturaleza y la meta que debe alcanzar esta ciencia: 1) la concepción de la sabiduría como ciencia que se ocupa de ciertos principios y causas; 2) la sabiduría como ciencia de los primeros principios y de las causas; 3) la determinación de las cuatro causas primeras como tarea de la filosofía primera. De este modo, se pretende mostrar que la Metafísica de Aristóteles es un intento para explicar las últimas cuestiones, el último porqué, indicando cuatro géneros diferentes de respuesta.

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The response of the Gulf Stream (GS) system to atmospheric forcing is generally linked either to the basin-scale winds on the subtropical gyre or to the buoyancy forcing from the Labrador Sea. This study presents a multiscale synergistic perspective to describe the low-frequency response of the GS system. The authors identify dominant temporal variability in the North Atlantic Oscillation (NAO), in known indices of the GS path, and in the observed GS latitudes along its path derived from sea surface height (SSH) contours over the period 1993-2013. The analysis suggests that the signature of interannual variability changes along the stream's path from 75 degrees to 55 degrees W. From its separation at Cape Hatteras to the west of 65 degrees W, the variability of the GS is mainly in the near-decadal (7-10 years) band, which is missing to the east of 60 degrees W, where a new interannual (4-5 years) band peaks. The latter peak (4-5 years) was missing to the west of 65 degrees W. The region between 65 degrees and 60 degrees W seems to be a transition region. A 2-3-yr secondary peak was pervasive in all time series, including that for the NAO. This multiscale response of the GS system is supported by results from a basin-scale North Atlantic model. The near-decadal response can be attributed to similar forcing periods in the NAO signal; however, the interannual variability of 4-5 years in the eastern segment of the GS path is as yet unexplained. More numerical and observational studies are warranted to understand such causality.

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The response of the Gulf Stream (GS) system to atmospheric forcing is generally linked either to the basin-scale winds on the subtropical gyre or to the buoyancy forcing from the Labrador Sea. This study presents a multiscale synergistic perspective to describe the low-frequency response of the GS system. The authors identify dominant temporal variability in the North Atlantic Oscillation (NAO), in known indices of the GS path, and in the observed GS latitudes along its path derived from sea surface height (SSH) contours over the period 1993-2013. The analysis suggests that the signature of interannual variability changes along the stream's path from 75 degrees to 55 degrees W. From its separation at Cape Hatteras to the west of 65 degrees W, the variability of the GS is mainly in the near-decadal (7-10 years) band, which is missing to the east of 60 degrees W, where a new interannual (4-5 years) band peaks. The latter peak (4-5 years) was missing to the west of 65 degrees W. The region between 65 degrees and 60 degrees W seems to be a transition region. A 2-3-yr secondary peak was pervasive in all time series, including that for the NAO. This multiscale response of the GS system is supported by results from a basin-scale North Atlantic model. The near-decadal response can be attributed to similar forcing periods in the NAO signal; however, the interannual variability of 4-5 years in the eastern segment of the GS path is as yet unexplained. More numerical and observational studies are warranted to understand such causality.