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Resumo:
Using US data for the period 1967:5-2002:4, this paper empirically investigates the performance of a Fed’s reaction function (FRF) that (i) allows for the presence of switching regimes, (ii) considers the long-short term spread in addition to the typical variables, (iii) uses an alternative monthly indicator of general economic activity suggested by Stock and Watson (1999), and (iv) considers interest rate smoothing. The estimation results show the existence of three switching regimes, two characterized by low volatility and the remaining regime by high volatility. Moreover, the scale of the responses of the Federal funds rate to movements in the rate of inflation and the economic activity index depends on the regime. The estimation results also show robust empirical evidence that the importance of the term spread in the FRF has increased over the sample period and the FRF has been more stable during the term of office of Chairman Greenspan than in the pre-Greenspan period.
Resumo:
The proportion of torpedograss tissue exposed to glyphosate at application rates of 0.28, 0.56, 1.12, 2.24, and 4.48 kg/ha affected control as measured by regrowth. The effect of tissue exposure was more pronounced as application rate decreased. This study suggests that higher rates of glyphosate need to be used during higher water levels, when less torpedograss tissue is exposed to herbicide spray and lower rates may be used during periods of low water levels. Addition of the water conditioning agent Quest (R) (0.25% v/v) to glyphosate spray mixtures diminished the influence of simulated rain events following glyphosate application. Twelve other adjuvants did not influence the effect of simulated rain events.
Resumo:
This study was designed to comprehensively analyze the differential expression of proteins from human umbilical vein endothelial cells (HUVECs) exposed to tumor conditioned medium (TCM) and to identify the key regulator in the cell cycle progression. The HUVECs were exposed to TCM from breast carcinoma cell line MDA-MB-231, then their cell cycle distribution was measured by flow cytometer (FCM). The role of protein in cell cycle progression was detected via two-dimensional polyacrylamide gel electrophoresis (2-DE) and western blotting. Following the stimulation of TCM, HUVECs showed a more cells in the S phase than did the negative control group (ECGF-free medium with 20% FBS), but the HUVECs' level was similar to the positive control group (medium with 25 mug/ml ECGF and 20% FBS). Increased expression of cyclin D-1/E and some changes in other related proteins occurred after incubation with TCM. From our results, we can conclude that breast carcinoma cell line MDA-MB-231 may secrete soluble pro-angiogenic factors that induce the HUVEC angiogenic switch, during which the expression of cell cycle regulator cyclin D-1/E increases and related proteins play an important role in this process.
Resumo:
A side-wall compression scramjet model with different combustor geometries has been tested in a propulsion tunnel that typically provides the testing flow with Mach number of 5.8, total temperature of 1800K, total pressure of 4.5MPa and mass flow rate of 4kg/s. This kerosene-fueled scramjet model consists of a side-wall compression inlet, a combustor and a thrust nozzle. A strut was used to increase the contraction ratio and to inject fuels, as well as a mixing enhancement device. Several wall cavities were also employed for flame-holding. In order to shorten the ignition delay time of the kerosene fuel, a little amount of hydrogen was used as a pilot flame. The pressure along the combustor has an evident raise after ignition occurred. Consequently thrust was observed during the fuel-on period. However, the thrust was still less than the drag of the scramjet model. For this reason, the drag variation produced by different strut and cavities was tested. Typical results showed that the cavities do not influence the drag so much, but the length of the strut does.