Convex Optimization, Stochastic Approximation, and Optimal Contract Management in Real-time Bidding

This thesis studies problems at the intersection of monotone and convex optimization, auction theory, and electronic commerce. Convex optimization and the theory of stochastic approximation serve as the basic practical and theoretical tools we have drawn upon. We solve important problems facing Demand Side Platforms (DSPs) and other demand aggregators (to be defined in the main body) in the e-commerce space, particularly in the field of real-time bidding (RTB). RTB is a real-time auction market, the primary application of which is the selling advertising space. Our main contribution to this field, at its most basic, is to recognize that certain optimal bidding problems can be re-cast as convex optimization problems. Particular focus will be placed upon the second price auction mechanism due to the strikingly simple structural results that hold in this case; but many results generalize to the first price auction mechanism under additional assumptions. We will also touch upon formal connections between these auction problems and two important problems in finance, namely the dark pool problem, and optimal portfolio construction

Cloud Computing As a Tool for Enhancing Ecological Goals?

Cloud computing has been introduced as a promising information technology (IT) that embodies not only economic advantages in terms of increased efficiency but also ecological gains through saving energy. The latter has become particularly important in view of the rising energy costs of IT. The present study analyzes whether necessary preconditions for accepting cloud computing as a new infrastructure, such as awareness and perceived net value, exist on the part of the users. The analysis is based on a combined research framework of the theory of reasoned action (TRA) and the technology acceptance model (TAM) in a cloud computing setting. Two consumer surveys, the one to elicit beliefs and the second to gain insight into the ranking of the variables, are employed. This study uses structural equation modeling (SEM) to evaluate the hypotheses. The results indicate support for the proposed research framework. Surprisingly however, the ecological factor does not play a role in forming cloud computing intentions, regardless of prior knowledge or experience. Empirical evidence of this study suggests increasing efforts for informing actual and potential users, particularly in respect to possible ecological advantages through applying the new IT infrastructure

Nanocrystalline Aggregation of Serine Detected by Electrospray Ionization Mass Spectrometry: Origin of the Stable Homochiral Gas-Phase Serine Octamer

Electrospray ionization sampling of 0.01 M solutions of serine reveals an unusually abundant protonated serine octamer, which demonstrates a strong preference for homochirality. Ion mobility spectra yield an experimental cross section that is consistent with a single “cubic” structure. Density functional theory calculations support experimental observations which suggest that the structure of the serine octamer is closely related to and formed from a small subsection of the crystal structure of anhydrous serine. The formation, bonding, and experimental constraints placed on the serine octamer are discussed in light of the proposed nanocrystalline structure. The mass spectra of the analogous molecules threonine and homoserine exhibit several similar features with that of serine and the likely structures for the octameric species are compared with that of the serine octamer. Finally, implications for the spontaneous symmetry breaking of a racemic mixture and the origin of life are addressed

Epidemiology, prehospital care and outcomes of patients arriving by ambulance with dyspnoea: An observational study

© 2016 The Author(s). Background: This study aimed to determine epidemiology and outcome for patients presenting to emergency departments (ED) with shortness of breath who were transported by ambulance. Methods: This was a planned sub-study of a prospective, interrupted time series cohort study conducted at three time points in 2014 and which included consecutive adult patients presenting to the ED with dyspnoea as a main symptom. For this sub-study, additional inclusion criteria were presentation to an ED in Australia or New Zealand and transport by ambulance. The primary outcomes of interest are the epidemiology and outcome of these patients. Analysis was by descriptive statistics and comparisons of proportions. Results: One thousand seven patients met inclusion criteria. Median age was 74 years (IQR 61-68) and 46.1 % were male. There was a high rate of co-morbidity and chronic medication use. The most common ED diagnoses were lower respiratory tract infection (including pneumonia, 22.7 %), cardiac failure (20.5%) and exacerbation of chronic obstructive pulmonary disease (19.7 %). ED disposition was hospital admission (including ICU) for 76.4 %, ICU admission for 5.6 % and death in ED in 0.9 %. Overall in-hospital mortality among admitted patients was 6.5 %. Discussion: Patients transported by ambulance with shortness of breath make up a significant proportion of ambulance caseload and have high comorbidity and high hospital admission rate. In this study, >60 % were accounted for by patients with heart failure, lower respiratory tract infection or COPD, but there were a wide range of diagnoses. This has implications for service planning, models of care and paramedic training. Conclusion: This study shows that patients transported to hospital by ambulance with shortness of breath are a complex and seriously ill group with a broad range of diagnoses. Understanding the characteristics of these patients, the range of diagnoses and their outcome can help inform training and planning of services