MECHANISM DESIGN WITH GENERAL UTILITIES

This thesis studies mechanism design from an optimization perspective. Our main contribution is to characterize fundamental structural properties of optimization problems arising in mechanism design and to exploit them to design general frameworks and techniques for efficiently solving the underlying problems. Not only do our characterizations allow for efficient computation, they also reveal qualitative characteristics of optimal mechanisms which are important even from a non-computational standpoint. Furthermore, most of our techniques are widely applicable to optimization problems outside of mechanism design such as online algorithms or stochastic optimization. Our frameworks can be summarized as follows. When the input to an optimization problem (e.g., a mechanism design problem) comes from independent sources (e.g., independent agents), the complexity of the problem can be exponentially reduced by (i) decomposing the problem into smaller subproblems, each one involving one input source, (ii) simultaneously optimizing the subproblems subject to certain relaxation of coupling constraints, and (iii) combining the solutions of the subproblems in a certain way to obtain an (approximately) optimal solution for the original problem. We use our proposed framework to construct optimal or approximately optimal mechanisms for several settings previously considered in the literature and to improve upon the best previously known results. We also present applications of our techniques to non-mechanism design problems such as online stochastic generalized assignment problem which itself captures online and stochastic versions of various other problems such as resource allocation and job scheduling

Priming of carbon and nitrogen mineralization in forest soils

Decomposition of soil organic matter (SOM) contributes significantly to the global carbon (C) cycle and climate feedbacks. SOM decomposition depends on soil microbial activities, and these activities are driven by the availability of C and other nutrients. Plant root exudates are known to alter decomposition of SOM, a phenomenon referred to as rhizosphere priming effects (RPE). In order to predict the effect of environmental changes such as elevated CO2 and increased N deposition on microbial SOM decomposition and release of CO2 to the atmosphere, we need a better understanding of the factors that regulate RPE. In this thesis, I present my results from priming experiments with and without plants. I studied the effect of root exudates on SOM decomposition by adding glucose to soil to simulate root exudation. I also performed experiments with living plants. The aim was to investigate how variations in C and N availability influence priming. I further aimed to determine how elevated CO2, N fertilization, and light intensity influence root exudation rates and priming. I also tested how priming influence gross N mineralization and protein depolymerization, and if this could be linked to the abundance of different microbial functional groups and extracellular enzyme activity.I found that the soil C:N ratio is a poor predictor of priming. Instead, my findings suggest that the C:N imbalance (soil C:N divided by microbial biomass C:N) could better predict priming. My findings suggest that C:N imbalances could induce priming by increasing the abundance of microbes able to decompose complex substrates such as lignin. My results further suggest that priming is a result of enhanced activity of extracellular oxidative enzymes, rather than a change in the concentration of enzymes. I also found that in addition to increasing N cycling rates, soil microbes could meet their increased N demand caused by C input through using the available N more efficiently. This suggests that plant C input might aggravate N limitation by promoting microbial N sequestration. My findings highlight that elevated CO2 and N deposition enhance plant C uptake, but they also increase the microbial respiration of SOM to an even greater extent. These findings suggest that in order to evaluate if elevated CO2 and N deposition increases terrestrial C sequestration, changes in the microbial decomposition of SOM also needs to be accounted for. Finally, my results demonstrated that physiological traits of different plant species, e.g. response to altered light intensity, also have important effects on RPE.In summary, my findings suggest that priming is of major importance not only for C cycling in forest soils, but also for N cycling. Stoichiometric imbalances in C and N, plant and microbial nutrient demands, and the microbial response to nutrient deficiency, are important factors regulating RPE. I also conclude that priming a result of stimulated activity of extracellular oxidative enzymes, rather than of increased concentration of such enzymes

A Fire Protection Analysis of KIPP Academy of Opportunity

The purpose of this report is to analyze and assess the life safety and fire protections systems of the KIPP Academy of Opportunity (KAO) charter school located in South Los Angeles. KAO is a 3-story building with a total area of 27,429 ft2 that was originally built in 2003 to serve 400 students. Two separate fire and life safety assessments were performed in this project to ensure the building meets the requirements by the building code and fire safety standards. The prescriptive based analysis includes assessment of structural design, construction materials, egress design, fire alarm, communication system, fire suppression system, flammability analysis, and smoke management. The results of the prescriptive based analysis showed that the building complies with the requirements of the building code and fire safety standards. In the performance-based analysis, two different fire scenarios were evaluated using FDS and Pathfinder programs. The Available Safe Egress Time (ASET) and Required Safe Egress Time (RSET) were calculated for each scenario to evaluate how occupants evacuate the building during a real-life fire event. The first fire scenario in the performance-based analysis was based on the 2nd recommended scenario in the life safety code. It is based on the assumption that an arson fire starts from a cluttered space under the first-floor stairways, compromises 1 of the 2 exits, and spreads into the corridors. The RSET was calculated as 4 minutes for the first floor, 15 minutes for the second floor, and 13 minutes for the third floor. However, the ASET was calculated as 3, 2.8, and 2 minutes for the first, second, and third floor, respectively. Therefore, the first fire scenario failed because ASET was smaller than RSET. It is recommended that the egress route be kept free of clutter and stairways doors kept closed at all times as a precaution. The second fire scenario was based on the 3rd fire scenario recommended in the life safety code. This fire occurs in an unoccupied staff lounge next to a multipurpose area which is considered a high occupancy room. Using FDS, the ASET was calculated as 4 minutes for the multi-purpose area and 90 seconds for the staff lounge. Also, the RSET for the multi-purpose area is calculated as 3.7 minutes. Since detection time starts when the staff lounge smoke detector is activated, the RSET is smaller than ASET. Therefore, this design was acceptable

Signature Verification Approach using Fusion of Hybrid Texture Features

In this paper, a writer-dependent signature verification method is proposed. Two different types of texture features, namely Wavelet and Local Quantized Patterns (LQP) features, are employed to extract two kinds of transform and statistical based information from signature images. For each writer two separate one-class support vector machines (SVMs) corresponding to each set of LQP and Wavelet features are trained to obtain two different authenticity scores for a given signature. Finally, a score level classifier fusion method is used to integrate the scores obtained from the two one-class SVMs to achieve the verification score. In the proposed method only genuine signatures are used to train the one-class SVMs. The proposed signature verification method has been tested using four different publicly available datasets and the results demonstrate the generality of the proposed method. The proposed system outperforms other existing systems in the literature.Comment: Neural Computing and Applicatio

Cardiac Involvement in Lysosomal Diseases

How to Cite this Article: Alaei F. Cardiac Involvement in Lysosomal Diseases. Iran J Child Neurol Autumn 2012; 6:4 (suppl. 1): 19.Pls see PDF.