Essays on College Major Choice: Determinants and Centralized Mechanisms

This dissertation contains three essays in applied microeconomics. The first chapter evaluatesthe welfare costs induced by limiting the number of choices in deferred acceptancemechanisms. I show that when the number of choices is capped, some students have to bestrategic and that increasing the size of the submittable list can result in better matches,and therefore lead to welfare improvement. I use Iranian college entrance dataset to estimatea novel discrete choice model for centralized university systems, in which I relax theindependence of unobserved preference shocks assumption. I validate the model with out of sample data from a quasi-experimental policy change, in which the list cap was increasedby 50 percent. In my counterfactual analysis, I calculate that a list cap of 10 choices insteadof 100 would incur a 14.2 percent welfare loss. This is equivalent to a 453 km increase inthe home-university distance, which is 2.6 times the average distance traveled by Iranianstudents. I also show that a more restrictive list cap does not affect students at the top andbottom of the ranking, but hurts students with average scores and benefits students in thelower quartile. In the second chapter, I use the aforementioned dataset to find determinantsof major choice. I estimate a rank ordered logit model of major choice and show that labormarket variables, specifically earnings and unemployment play a significant role in choiceof majors by students. The model shows that students prefer majors with higher expectedincome and expected employment rate. This study also suggests that many students care more about the school they are applying to, rather than the major. Several explanations ispossible, for example prestige of some schools might be one reason. Credit constraints thatfamilies face or the cultural barriers might also play a role for those students who prefer tostay in their hometown even at the price of studying a major they are not very interestedin. Finally, in the third chapter I use neural networks to predict the number of quartersthat it takes a student with certain characteristics to graduate from UCLA. I also define asurvival model, in such those who did graduate before sixth year were survivors and thosewho couldn't were the failures

Traditional Vs. Contemporary Managerial/Cost Accounting Techniques Differences Between Opinions Of Educators And Practitioners

From the mid 1980s, the start of new movements in the field of managerial/cost accounting, a gap has emerged between the opinions of academia and practitioners regarding the degree of usefulness of managerial/cost accounting techniques. It is believed that practitioners generally prefer managerial/cost accounting techniques which are simple, practical and economically applicable. On the other hand, many authors and academia believe that the traditional managerial/cost accounting techniques are obsolete and not effective for managerial decision-making purposes. As stated by one author, most of the traditional management/cost accounting information are usually too late, too aggregated, and too distorted to be relevant for decision-making purposes. Despite the considerable criticisms to the traditional techniques and increasing interest in developing new managerial/cost accounting models in recent years, the traditional management/cost accounting techniques are still widely used by many organizations. Based on the above and many other studies, some disagreements appear to exist between the perception of academia and practitioner regarding the degree of usefulness of some traditional and contemporary (emergent) managerial/cost accounting techniques and practices. The objectives of this research were to determine (a) whether a real gap existed between the perceptions of academia and practitioners regarding the usefulness of traditional and contemporary managerial/cost accounting techniques and practices and (b) if such a real gap existed, should the practitioner follow academia or should academia modify their theoretical thinking according to practitioners’ practical experiences. In addition, it was planned in this research to determine the degree of usefulness of different managerial/cost accounting techniques and practices, as well as the type of skills and characteristics demanded from our graduates, from the view points of academia and practitioners. The outcomes of this study were expected to provide useful and empirical information to the authorities in the higher education for the development of more effective curriculum in the field of managerial/cost accounting

Modeling driver's evasive behavior during safety-critical lane changes:Two-dimensional time-to-collision and deep reinforcement learning

Lane changes are complex driving behaviors and frequently involve safety-critical situations. This study aims to develop a lane-change-related evasive behavior model, which can facilitate the development of safety-aware traffic simulations and predictive collision avoidance systems. Large-scale connected vehicle data from the Safety Pilot Model Deployment (SPMD) program were used for this study. A new surrogate safety measure, two-dimensional time-to-collision (2D-TTC), was proposed to identify the safety-critical situations during lane changes. The validity of 2D-TTC was confirmed by showing a high correlation between the detected conflict risks and the archived crashes. A deep deterministic policy gradient (DDPG) algorithm, which could learn the sequential decision-making process over continuous action spaces, was used to model the evasive behaviors in the identified safety-critical situations. The results showed the superiority of the proposed model in replicating both the longitudinal and lateral evasive behaviors

Synthesis and Biological Evaluation of novel Quinoxaline containing N-substituted thiazolidine-2,4-dione derivatives as Anti-cancer Agents

Introduction: Quinoxalines belong to the N-containing heterocyclic compounds that stand out as having promising biological activity due to their privileged scaffold. Quinoxaline derivatives constitute the basis of many insecticides, fungicides, herbicides, as well as being important in human health and as receptor antagonists. On the other, the compounds containing thiazolidine-2,4-dione have demonstrated wide range of pharmacological activities, which include antimicrobial, antiviral, antidiabetic and anticancer activity. In this research, we have synthesised a new quinoxaline derivatives containing N-substituted thiazolidine-2,4-dione derivatives and evaluated for antitumor activity against a 3-cell line panel, consisting of MCF7 (breast), NCI-H460 (lung), and SF-268 (CNS). Methods and Results: In a 250 ml three necked flask equipped with teflon coated mechanical stir bar, chloroacetic acid and thiourea have been dissolved in distilled water and the contents of the flask were heated in the presence of hydrochloric acid. The precipitate was filtered and washed with water and dried before recrystalization. Consequently, the new synthesized thiazolidinedione derivatives were condensed in situ by quinoxaline aldehydes and substituted benzyl halides in N,N-Dimethylformamide. The resulted products were washed with water and then recrystallized in appropriate solvent. Structures of all the synthesized compounds were confirmed by IR, 1H NMR, 13CNMR, and Mass spectral data. The MTT assay of synthesized hybrids showed promising and effective anti-cancer activity against 3-cell cell lines. The current results indicate that these quinoxaline derivatives are novel and promising agents for further development towards a treatment for cancer. conclusion: In the present study, series of new N-thiazolidine-2,4-dione incorporated quinoxaline ring were synthesized. All compounds were screened against two different cancer cell lines using MTT assay method

Control of an IPMC soft actuator using adaptive full-order recursive terminal sliding mode

The ionic polymer metal composite (IPMC) actuator is a kind of soft actuator that can work for underwater applications. However, IPMC actuator control suffers from high nonlinearity due to the existence of inherent creep and hysteresis phenomena. Furthermore, for underwater applications, they are highly exposed to parametric uncertainties and external disturbances due to the inherent characteristics and working environment. Those factors significantly affect the positioning accuracy and reliability of IPMC actuators. Hence, feedback control techniques are vital in the control of IPMC actuators for suppressing the system uncertainty and external disturbance. In this paper, for the first time an adaptive full-order recursive terminal sliding-mode (AFORTSM) controller is proposed for the IPMC actuator to enhance the positioning accuracy and robustness against parametric uncertainties and external disturbances. The proposed controller incorporates an adaptive algorithm with terminal sliding mode method to release the need for any prerequisite bound of the disturbance. In addition, stability analysis proves that it can guarantee the tracking error to converge to zero in finite time in the presence of uncertainty and disturbance. Experiments are carried out on the IPMC actuator to verify the practical effectiveness of the AFORTSM controller in comparison with a conventional nonsingular terminal sliding mode (NTSM) controller in terms of smaller tracking error and faster disturbance rejection

Traffic flow optimization with QoS constrained network admission control

The paper proposes a control design method in order to gate input flow to a protected urban vehicular network such that travel time Quality of Service (QoS) constraints are preserved within the network. In view of the network to be protected (also called the region), two types of queues are distinguished: external and internal. While external queues represent vehicles waiting to enter the protected network, an internal queue can be used to describe the network's aggregated behaviour. By controlling the number of vehicles entering the internal queue, the travel time within the network subject to the vehicular conservation law and the Network Fundamental Diagram (NFD) can be subsequently controlled. The admission controller can thus be interpreted as a mechanism which transforms the unknown arrival process governing the number of vehicles entering the network to a regulated process, such that prescribed QoS requirements on travel time in the network and upper bound on the external queue are satisfied. The admission control problem is formulated as a constrained convex optimization problem and a Model Predictive Control (MPC) problem. A case study demonstrates the benefits of the admission control mechanisms proposed

Network Fundamental Diagram (NFD) and traffic signal control: First empirical evidences from the city of Santander

According to recent literature, the aggregate traffic conditions of an urban road network may be measured by an asymmetric inverse-U shaped diagram, called Network or Macroscopic Fundamental Diagram (NFD or MFD). The research on NFD was finalizes for applications connected to congestion control by means of gating, pricing schemes, multi-modal network analysis, freight vehicle routing. The control of urban road networks by means of NFD is a promising research area, where new methods and models are proposed to reduce traffic congestion and delay. The general objective of the research is to investigate if and in which measure the NFD profile (estimated by means of observed traffic data) changes according to the control strategy adopted for junction signals in an urban area. The first empirical evidences presented in this paper are related to a portion of Santander urban area, where a specific zone has been identified according to traffic characteristics and land uses. Data from traffic loops are collected and correlated with the signal control plans during a working day at link (flow-density diagrams) and network levels (NFD). Some preliminary considerations are derived from the empirical results. The cycle length with a fixed regulation plan does not influence the main traffic variables (flow, density) at link and network level, but these results cannot be generalized