| 91. |
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| 92. |
- Bender, Frida A-M, 1978-
(author)
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Earth's albedo in a changing climate
- 2009
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Doctoral thesis (other academic/artistic)abstract
- The albedo is a key parameter in the radiative budget of the Earth and a primary determinant of the planetary temperature and is therefore also central to questions regarding climate stability, climate change and climate sensitivity. Climate models and satellite observations are essential for studying the albedo, and the parameters determining it, on large spatial and temporal scales. Although climate models are able to capture the large-scale characteristics of the albedo, a bias is found between modelled and observed global albedo estimates, and on a regional scale particular problematic regions can be identified. Cloud parameters, that are of great importance for determining the albedo, vary widely among models, but lack of observations makes constraining models, and even evaluating models, difficult. The freedom of variability for cloud parameters can be used to make models agree with observations of the better constrained radiative budget. It is shown that tuning a model to different radiative budget estimates by altering cloud parameters can influence the climate sensitivity of the model, but the effect seen is small, compared to the range of climate sensitivities estimated by different models. Despite their different parameterizations of clouds, aerosols etc., models do have fundamental features in common, which can further the understanding of the real climate system. For instance it is found that sensitivity to volcanic forcing is related to climate sensitivity in an ensemble of models. If this relation is valid for the real climate as well, observations of the volcanic sensitivity can help restrict the climate sensitivity. The range of climate sensitivity estimates in models can largely be attributed to variations in cloud response to forcing. It is found that in models with high climate sensitivity changes in cloud cover and cloud reflectivity enhance a positive radiative forcing due to increased CO2 concentrations, feeding back on the warming and in models with low climate sensitivity, cloud response counteracts the positive radiative forcing and warming induced by the same forcing. As a consequence the total albedo response to increased CO2 forcing is found to be stronger (more negative) in high sensitivity models and vice versa. Cloud albedo and its variation between different cloud regimes, is important in this regard, yet not well known. A method based on the relation between cloud fraction and albedo is presented, giving a way to estimate regional cloud albedo, primarily for homogeneous cloud regimes, but possibly also extended to a global scale.
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| 93. |
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| 94. |
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| 95. |
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| 96. |
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| 97. |
- Collins, J, et al.
(author)
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Unintegrated parton density functions
- 2005
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In: CERN Reports. - 0007-8328. ; CERN-2005-014, s. 256-273
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Conference paper (other academic/artistic)abstract
- An overview on activities to determine unintegrated parton density functions is given and the concept and need for unintegrated PDFs is discussed. It is also argued that it is important to reformulate perturbative QCD results in terms of fully unintegrated parton densities, differential in all components of the parton momentum. Also the need for non-linear BFKL evolution is discussed and results using the BK equation supplemented by DGLAP corrections at short distances is reviewed. Finally the use unintegrated generalized parton distributions for hard diffractive processes is discussed.
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| 98. |
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| 99. |
- Dahlöf, Björn, 1953, et al.
(author)
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Prevention of cardiovascular events with an antihypertensive regimen of amlodipine adding perindopril as required versus atenolol adding bendroflumethiazide as required, in the Anglo-Scandinavian Cardiac Outcomes Trial-Blood Pressure Lowering Arm (ASCOT-BPLA): a multicentre randomised controlled trial
- 2005
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In: Lancet. - 1474-547X. ; 366:9489, s. 895-906
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Journal article (peer-reviewed)abstract
- BACKGROUND: The apparent shortfall in prevention of coronary heart disease (CHD) noted in early hypertension trials has been attributed to disadvantages of the diuretics and beta blockers used. For a given reduction in blood pressure, some suggested that newer agents would confer advantages over diuretics and beta blockers. Our aim, therefore, was to compare the effect on non-fatal myocardial infarction and fatal CHD of combinations of atenolol with a thiazide versus amlodipine with perindopril. METHODS: We did a multicentre, prospective, randomised controlled trial in 19 257 patients with hypertension who were aged 40-79 years and had at least three other cardiovascular risk factors. Patients were assigned either amlodipine 5-10 mg adding perindopril 4-8 mg as required (amlodipine-based regimen; n=9639) or atenolol 50-100 mg adding bendroflumethiazide 1.25-2.5 mg and potassium as required (atenolol-based regimen; n=9618). Our primary endpoint was non-fatal myocardial infarction (including silent myocardial infarction) and fatal CHD. Analysis was by intention to treat. FINDINGS: The study was stopped prematurely after 5.5 years' median follow-up and accumulated in total 106 153 patient-years of observation. Though not significant, compared with the atenolol-based regimen, fewer individuals on the amlodipine-based regimen had a primary endpoint (429 vs 474; unadjusted HR 0.90, 95% CI 0.79-1.02, p=0.1052), fatal and non-fatal stroke (327 vs 422; 0.77, 0.66-0.89, p=0.0003), total cardiovascular events and procedures (1362 vs 1602; 0.84, 0.78-0.90, p<0.0001), and all-cause mortality (738 vs 820; 0.89, 0.81-0.99, p=0.025). The incidence of developing diabetes was less on the amlodipine-based regimen (567 vs 799; 0.70, 0.63-0.78, p<0.0001). INTERPRETATION: The amlodipine-based regimen prevented more major cardiovascular events and induced less diabetes than the atenolol-based regimen. On the basis of previous trial evidence, these effects might not be entirely explained by better control of blood pressure, and this issue is addressed in the accompanying article. Nevertheless, the results have implications with respect to optimum combinations of antihypertensive agents.
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| 100. |
- Davis, Faith G, et al.
(author)
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Issues of diagnostic review in brain tumor studies : from the brain tumor epidemiology consortium
- 2008
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In: Cancer Epidemiology, Biomarkers and Prevention. - : American Association for Cancer Research (AACR). - 1055-9965 .- 1538-7755. ; 17:3, s. 484-489
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Journal article (peer-reviewed)abstract
- Epidemiologists routinely conduct centralized single pathology reviews to minimize interobserver diagnostic variability, but this practice does not facilitate the combination of studies across geographic regions and institutions where diagnostic practices differ. A meeting of neuropathologists and epidemiologists focused on brain tumor classification issues in the context of protocol needs for consortial studies (http://epi.grants.cancer.gov/btec/). It resulted in recommendations relevant to brain tumors and possibly other rare disease studies. Two categories of brain tumors have enough general agreement over time, across regions, and between individual pathologists that one can consider using existing diagnostic data without further review: glioblastomas and meningiomas (as long as uniform guidelines such as those provided by the WHO are used). Prospective studies of these tumors benefit from collection of pathology reports, at a minimum recording the pathology department and classification system used in the diagnosis. Other brain tumors, such as oligodendroglioma, are less distinct and require careful histopathologic review for consistent classification across study centers. Epidemiologic study protocols must consider the study specific aims, diagnostic changes that have taken place over time, and other issues unique to the type(s) of tumor being studied. As diagnostic changes are being made rapidly, there are no readily available answers on disease classification issues. It is essential that epidemiologists and neuropathologists collaborate to develop appropriate study designs and protocols for specific hypothesis and populations.
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