祁连山海北高寒草甸地区微气候特征的观测研究

对祁连山海北高寒草甸地区近夏至日微气象观测分析表明: (1) 14:00 (北京时,下同) 太阳总辐射瞬时值最高可达1061 W·m-2 , 净辐射、反射辐射、光合有效辐射和紫外辐射分别为670、218、380 和168 W·m-2 , 分别约为太阳总辐射的58 %、20 %、36 %和14 % , 6 月下旬日平均反射率约为0. 22 ; (2) 土壤热通量、感热通量和潜热通量瞬时值最大分别为91、274 和362 W·m-2 , 相应占净辐射的比例为20 %、38 %和42 %; (3) 地—气温度在一定范围的水平和垂直方向变化较为剧烈, 大气逆温约出现于20 :00 至次日11 :00 , 午夜01 :00 最强; (4)风速阵性强, 有显著日变化的时间性分布。

A European Perspective on the Precautionary Principle, Food Safety and the Free Trade Imperative of the WTO

A European Perspective on the Precautionary Principle, Food Safety and the Free Trade Imperative of the WTO. European Law Review, Vol.27, No.2. April 2002, pp.138-155. RAE2008

Rural Housing, Affordable Housing and Speaking the Language of an Unaffordable Hearth

Huws, Catrin, 'Rural Housing, Affordable Housing and Speaking the Language of an Unaffordable Hearth', Journal of Planning and Environment Law, (2007) pp.1648-1660 RAE2008

Unfinished Business from Potsdam: Britain, West Germany, and the Oder-Neisse line, 1945-1962

Hughes, R. G., 'Unfinished Business from Potsdam: Britain, West Germany, and the Oder-Neisse line, 1945-1962', International History Review (2005) 27(2) pp.259-294 RAE2008

The Power of Partnerships in Global Governance

Abrahamsen, Rita, 'The Power of Partnerships in Global Governance', Third World Quarterly (2004) 25(8) pp.1453-1467 RAE2008

An econometric analysis of international air travel demand in Saudi Arabia

Abed, S. Y., Ba-Fail, A. O., & Jasimuddin, S. (2001). An econometric analysis of international air travel demand in Saudi Arabia. Journal of Air Transport Management, 7(3), 143-148 RAE2008

Os motivos da não erupção dos terceiros molares

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária

PARAMETERS AFFECTING THE IMAGING AND DETECTION OF MICROBUBBLES IN BLOOD

Stabilized micron-sized bubbles, known as contrast agents, are often injected into the body to enhance ultrasound imaging of blood flow. The ability to detect such bubbles in blood depends on the relative magnitude of the acoustic power backscattered from the microbubbles (‘signal’) to the power backscattered from the red blood cells (‘noise’). Erythrocytes are acoustically small (Rayleigh regime), weak scatterers, and therefore the backscatter coefficient (BSC) of blood increases as the fourth power of frequency throughout the diagnostic frequency range. Microbubbles, on the other hand, are either resonant or super-resonant in the range 5-30 MHz. Above resonance, their total scattering cross-section remains constant with increasing frequency. In the present thesis, a theoretical model of the BSC of a suspension of red blood cells is presented and compared to the BSC of Optison® contrast agent microbubbles. It is predicted that, as the frequency increases, the BSC of red blood cell suspensions eventually exceeds the BSC of the strong scattering microbubbles, leading to a dramatic reduction in signal-to-noise ratio (SNR). This decrease in SNR with increasing frequency was also confirmed experimentally by use of an active cavitation detector for different concentrations of Optison® microbubbles in erythrocyte suspensions of different hematocrits. The magnitude of the observed decrease in SNR correlated well with theoretical predictions in most cases, except for very dense suspensions of red blood cells, where it is hypothesized that the close proximity of erythrocytes inhibits the acoustic response of the microbubbles.