1,149 research outputs found
The United Arab Emirates : a study in survival
This present thesis seeks to account for the UAE's remarkable socio-economic development path while also attempting to explain the survival of the state's seemingly anachronistic political structures. In doing so, the thesis proceeds to set up a multi-layered framework drawing upon and reconciling elements of the two major schools of development theory. Specifically, a dependency analysis is used to demonstrate the UAE's inherited situation, including the region's historic peripheralisation, its early rentier structures, and the external reinforcement of a client elite; while a combination of rentier-dependency models and revised modernisation theories are used to illustrate the way in which the UAE's contemporary monarchies have managed to consolidate their position and secure considerable political stability, which is itself an important prerequisite of the modernisation process. With regard to the recent attempts of these 'modernising monarchies' to improve die more negative aspects of their dependency situation, it is shown that while there have been successes there have also been serious development pathologies, and in many ways these must be regarded as the hidden costs of escaping the inevitability of early modernisation predictions and the demise of tradition. Essentially, viewed within a Weberian variant of modernisation theory, the strengthening of the structures which allowed for the stability in the first place can in many cases be seen to have gone too far and has now made legal-rational objectives difficult to achieve. Finally, however, it is suggested that greater modernisation, especially in the form of positive globalising forces, may still provide solutions for these problems. Indeed, while die first wave of globalisation may have reinforced entrenched dependency structures, there are nevertheless clear indications that something of a second wave may well lead to liberalising reforms, a more diversified economy, and a stronger civil society
Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems
This interim report consists of two reports: 'Space Radiation Effects on Si APDs for GLAS' and 'Computer Simulation of Avalanche Photodiode and Preamplifier Output for Laser Altimeters.' The former contains a detailed description of our proton radiation test of Si APD's performed at the Brookhaven National Laboratory. The latter documents the computer program subroutines which were written for the upgrade of NASA's GLAS simulator
Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems
This Interim report consists of a manuscript, 'Receiver Design for Satellite to Satellite Laser Ranging Instrument,' and copies of two papers we co-authored, 'Demonstration of High Sensitivity Laser Ranging System' and 'Semiconductor Laser-Based Ranging Instrument for Earth Gravity Measurements. ' These two papers were presented at the conference Semiconductor Lasers, Advanced Devices and Applications, August 21 -23, 1995, Keystone Colorado. The manuscript is a draft in the preparation for publication, which summarizes the theory we developed on space-borne laser ranging instrument for gravity measurements
Receiver Design, Performance Analysis, and Evaluation for Space-Borne Laser Altimeters and Space-to-Space Laser Ranging Systems
This progress report consists of two separate reports. The first one describes our work on the use of variable gain amplifiers to increase the receiver dynamic range of space borne laser altimeters such as NASA's Geoscience Laser Altimeter Systems (GLAS). The requirement of the receiver dynamic range was first calculated. A breadboard variable gain amplifier circuit was made and the performance was fully characterized. The circuit will also be tested in flight on board the Shuttle Laser Altimeter (SLA-02) next year. The second report describes our research on the master clock oscillator frequency calibration for space borne laser altimeter systems using global positioning system (GPS) receivers
Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems
We report here the design and the performance measurements of the breadboard receiver of the Geoscience Laser Altimeter System (GLAS). The measured ranging accuracy was better than 2 cm and 10 cm for 5 ns and 30 ns wide received laser pulses under the expected received signal level, which agreed well with the theoretical analysis. The measured receiver sensitivity or the link margin was also consistent with the theory. The effects of the waveform digitizer sample rate and resolution were also measured
Receiver design, performance analysis, and evaluation for space-borne laser altimeters and space-to-space laser ranging systems
Laser altimeters measure the time of flight of the laser pulses to determine the range of the target. The simplest altimeter receiver consists of a photodetector followed by a leading edge detector. A time interval unit (TIU) measures the time from the transmitted laser pulse to the leading edge of the received pulse as it crosses a preset threshold. However, the ranging error of this simple detection scheme depends on the received, pulse amplitude, pulse shape, and the threshold. In practice, the pulse shape and the amplitude are determined by the target target characteristics which has to be assumed unknown prior to the measurement. The ranging error can be improved if one also measures the pulse width and use the average of the leading and trailing edges (half pulse width) as the pulse arrival time. The ranging error becomes independent of the received pulse amplitude and the pulse width as long as the pulse shape is symmetric. The pulse width also gives the slope of the target. The ultimate detection scheme is to digitize the received waveform and calculate the centroid as the pulse arrival time. The centroid detection always gives unbiased measurement even for asymmetric pulses. In this report, we analyze the laser altimeter ranging errors for these three detection schemes using the Mars Orbital Laser Altimeter (MOLA) as an example
Depressive Symptoms and Health-Related Quality of Life Among Participants in the Pasos Adelante Chronic Disease Prevention and Control Program, Arizona, 2005-2008
Introduction
Chronic diseases are the leading causes of death in the United States and have been associated with depressive symptoms and poor health-related quality of life (HRQOL). This study examined whether depressive symptoms and HRQOL indicators changed among participants in Pasos Adelante, a chronic disease prevention and control program implemented in a US–Mexico border community.
Methods
Pasos Adelante was a 12-week promotora-led program that included educational sessions and walking groups. We used the Centers for Epidemiologic Studies Depression Scale (CES-D) and the Center for Disease Control’s “Healthy Days” measures to measure depressive symptoms and HRQOL. We used linear mixed-effects models and general estimating equations to analyze changes in CES-D scores and HRQOL indicators from baseline to postprogram and from postprogram to 3-month follow-up.
Results
At baseline, participants had a mean of 7.1 physically unhealthy days, 7.4 mentally unhealthy days, and 3.9 days of activity limitation. The mean number of physically and mentally unhealthy days declined significantly from baseline to postprogram, but the mean number of activity limitation days did not. At baseline, 42.6% of participants reported their health as fair/poor; 20.8% of participants reported frequent mental distress, and 31.8% had a CES-D score of 16 or more. All 3 proportions declined from baseline to postprogram. No significant changes occurred between postprogram and follow-up.
Conclusion
Participants in Pasos Adelante showed improvement in depressive symptoms and several HRQOL indicators. Future studies should use an experimental design with a comparison group to determine whether these findings can be replicated and to examine potential mediators and moderators of program effects
Dual-specificity phosphatase 5 controls the localized inhibition, propagation, and transforming potential of ERK signaling
Deregulated extracellular signal-regulated kinase (ERK) signaling drives cancer growth. Normally, ERK activity is self-limiting by the rapid inactivation of upstream kinases and delayed induction of dual-specificity MAP kinase phosphatases (MKPs/DUSPs). However, interactions between these feedback mechanisms are unclear. Here we show that, although the MKP DUSP5 both inactivates and anchors ERK in the nucleus, it paradoxically increases and prolongs cytoplasmic ERK activity. The latter effect is caused, at least in part, by the relief of ERK-mediated RAF inhibition. The importance of this spatiotemporal interaction between these distinct feedback mechanisms is illustrated by the fact that expression of oncogenic BRAF(V600E), a feedback-insensitive mutant RAF kinase, reprograms DUSP5 into a cell-wide ERK inhibitor that facilitates cell proliferation and transformation. In contrast, DUSP5 deletion causes BRAF(V600E)-induced ERK hyperactivation and cellular senescence. Thus, feedback interactions within the ERK pathway can regulate cell proliferation and transformation, and suggest oncogene-specific roles for DUSP5 in controlling ERK signaling and cell fate
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