The Effect of Adolescent Health on Educational Outcomes: Causal Evidence using ‘Genetic Lotteries’ between Siblings

There has been growing interest in using specific genetic markers as instrumental variables in attempts to assess causal relationships between health status and socioeconomic outcomes, including human capital accumulation. In this paper we use a combination of family fixed effects and genetic marker instruments to show strong evidence that inattentive symptoms of ADHD in childhood and depressive symptoms as an adolescent are linked with years of completed schooling. Our estimates suggest that controlling for family fixed effects is important but these strategies cannot fully account for the endogeneity of poor mental heath. Finally, our results demonstrate that the presence of comorbid conditions present immense challenges for empirical studies that aim to estimate the impact of specific health conditions.Education Outcomes, Depression, Genetic Markers, ADHD, Obesity, Family Fixed Effects, and Instrumental Variables

Fault detection and location in DC systems from initial di/dt measurement

The use of DC for primary power distribution has the potential to bring significant design, cost and efficiency benefits to a range of power transmission and distribution applications. The use of active converter technologies within these networks is a key enabler for these benefits to be realised, however their integration can lead to exceptionally demanding electrical fault protection requirements, both in terms of speed and fault discrimination. This paper describes a novel fault detection method which exceeds the capability of many current protection methods in order to meet these requirements. The method utilises fundamental characteristics of the converter filter capacitance’s response to electrical system faults to estimate fault location through a measurement of fault path inductance. Crucially, the method has the capability to detect and discriminate fault location within microseconds of the fault occurring, facilitating its rapid removal from the network

Impact of converter interface type on the protection requirements for DC aircraft power systems

The utilization of converter interfaces has the potential to significantly alter the protection system design requirements in future aircraft platforms. However, the impact these converters will have can vary widely, depending on the topology of converter, its filter requirements and its control strategy. This means that the precise impact on the network fault response is often difficult to quantify. Through the analysis of example converter topologies and literature on the protection of DC networks, this paper tackles this problem by identifying key design characteristics of converters which influence their fault response. Using this information, the converters are classified based on their general fault characteristics, enabling potential protection issues and solutions to be readily identified. Finally, the paper discusses the potential for system level design benefits through the optimisation of converter topology and protection system design

Determination of protection system requirements for DC UAV electrical power networks for enhanced capability and survivability

A growing number of designs of future Unmanned Aerial Vehicle (UAV) applications utilise dc for the primary power distribution method. Such systems typically employ large numbers of power electronic converters as interfaces for novel loads and generators. The characteristic behaviour of these systems under electrical fault conditions, and in particular their natural response, can produce particularly demanding protection requirements. Whilst a number of protection methods for multi-terminal dc networks have been proposed in literature, these are not universally applicable and will not meet the specific protection challenges associated with the aerospace domain. Through extensive analysis, this paper seeks to determine the operating requirements of protection systems for compact dc networks proposed for future UAV applications, with particular emphasis on dealing with the issues of capacitive discharge in these compact networks. The capability of existing multi-terminal dc network protection methods and technologies are then assessed against these criteria in order to determine their suitability for UAV applications. Recommendations for best protection practice are then proposed and key inhibiting research challenges are discussed

Orthognathic Surgical Outcomes in Patients With and Without Craniofacial Anomalies

Purpose The objective of this study is to examine hospitalization outcomes after orthognathic surgery. This study tests the hypothesis that patients with craniofacial anomalies have higher billed hospital charges, longer lengths of stay, and increased odds of development of infectious complications when compared with patients without craniofacial anomalies. Materials and Methods The Nationwide Inpatient Sample for the years 2012 and 2013 was used. All patients who underwent an orthognathic surgical procedure were selected. The primary independent variable of interest was presence of a congenital cleft and/or craniofacial anomaly. The outcome variables were the occurrence of complications, billed hospital charges, and length of stay. Multivariable logistic and linear regression models were used to examine the effect of the presence of craniofacial anomalies on outcomes. Results During the study period, a total of 16,515 patients underwent an orthognathic surgical procedure in the United States. Of these patients, 2,760 had a cleft and/or craniofacial anomaly. An infectious complication occurred in 7.4% of those with a craniofacial anomaly (compared with 0.6% of those without a craniofacial anomaly). The mean billed hospital charges in those with a craniofacial anomaly was $139,317 (compared with$56,189 in those without a craniofacial anomaly). The mean length of stay in the hospital in patients with a craniofacial anomaly was 8.8 days (compared with 1.8 days in those without a craniofacial anomaly). These differences in outcomes between patients with and patients without craniofacial anomalies were significant after we adjusted for patient- and hospital-level confounders. Conclusions Patients with a craniofacial anomaly are at higher risk of development of infectious complications, have higher hospital charges, and stay in the hospital for a longer duration after orthognathic surgery when compared with those without a craniofacial anomaly

Petri net models of program execution in data flow environments

The computer systems of the eighties are expected to be designed using powerful low-cost distributed parts to achieve increases in computing power and concurrency. The resulting complexity due to the interaction and communication between these parts requires new methods for the analysis of the behavior of these systems. One such class of architectures, based on the concept of data flow, is designed to exploit the inherent parallelism within a program. In these computers, traditional sequencing constraints are removed and an operation is enabled for execution as soon as its operands are available;A method for approximating the time required to execute a data flow program (assuming adequate computing resources) is described. This method is applied to the static program graph at compile time and yields a parameterized equation for execution time performance. Based on a Petri net analysis and combined with more traditional approaches, this method is recursively applied to abstract operations in the program graph using a top-down approach. While this approach may introduce approximations at each stage, the major benefit is a significant reduction over other techniques in the time required for the analysis

Optimizing the roles of unit and non-unit protection methods within DC microgrids

The characteristic behavior of physically compact, multiterminal dc networks under electrical fault conditions can produce demanding protection requirements. This represents a significant barrier to more widespread adoption of dc power distribution for microgrid applications. Protection schemes have been proposed within literature for such networks based around the use of non-unit protection methods. This paper shows however that there are severe limitations to the effectiveness of such schemes when employed for more complex microgrid network architectures. Even current differential schemes, which offer a more effective, though costly, protection solution, must be carefully designed to meet the design requirements resulting from the unique fault characteristics of dc microgrids. This paper presents a detailed analysis of dc microgrid behavior under fault conditions, illustrating the challenging protection requirements and demonstrating the shortcomings of non-unit approaches for these applications. Whilst the performance requirements for the effective operation of differential schemes in dc microgrids are shown to be stringent, the authors show how these may be met using COTS technologies. The culmination of this work is the proposal of a flexible protection scheme design framework for dc microgrid applications which enables the required levels of fault discrimination to be achieved whilst minimizing the associated installation costs

TARGET MARKETS FOR RETAIL OUTLETS OF LANDSCAPE PLANTS

Merchandisers of landscape plants can increase the effectiveness of their marketing strategies by identifying target markets. Using a full information maximum likelihood tobit procedure on a system of three equations, target markets for different types of retail outlets in Georgia were identified. The results lend support and empirical evidence to the premise that different retail outlet types have different target markets and thus should develop different market strategies. The estimated target markets are identified and possible marketing strategies suitable for each type of retail outlet are suggested.Crop Production/Industries,

Modeling and simulation enabled UAV electrical power system design

With the diversity of mission capability and the associated requirement for more advanced technologies, designing modern unmanned aerial vehicle (UAV) systems is an especially challenging task. In particular, the increasing reliance on the electrical power system for delivering key aircraft functions, both electrical and mechanical, requires that a systems-approach be employed in their development. A key factor in this process is the use of modeling and simulation to inform upon critical design choices made. However, effective systems-level simulation of complex UAV power systems presents many challenges, which must be addressed to maximize the value of such methods. This paper presents the initial stages of a power system design process for a medium altitude long endurance (MALE) UAV focusing particularly on the development of three full candidate architecture models and associated technologies. The unique challenges faced in developing such a suite of models and their ultimate role in the design process is explored, with case studies presented to reinforce key points. The role of the developed models in supporting the design process is then discussed

Protection of physically compact multiterminal DC power systems

The use of DC for primary power distribution has the potential to bring significant design, cost and efficiency benefits to microgrid, shipboard and aircraft applications. The integration of active converter technologies within these networks is a key enabler for these benefits to be realised, however their influence on an electrical network's fault response can lead to exceptionally demanding protection requirements. This represents a significant barrier to more widespread adoption of DC power distribution. The principle challenge within the field is to develop protection solutions which do not significantly detract from the advantages which DC networks offer. This objective leads the thesis to not only consider how the protection challenges may be overcome but also how this can be achieved in a manner which can benefit the overall design of a system, inclusive of various system design objectives. The thesis proposes that this objective can be achieved through the operation of network protection within the initial transient period following the occurrence of a fault. In seeking to achieve this aim, the work presented within this thesis makes a number of contributions. The thesis categorises converter type based on the components which influence their fault response and then presents an analysis of the natural fault response of compact multiterminal DC power distribution networks containing these converters. Key factors such as the peak magnitudes and formation times of fault current profiles are determined and quantified as a function of network parameters, enabling protection system operating requirements to be established. Secondary fault effects such as voltage transients are also identified and quantified to illustrate the impact of suboptimal protection system operation. The capabilities of different protection methods and technologies for achieving the proposed operating requirements are then analysed. Significant conclusions are: solid state breaking technologies are essential to achieving operating targets and severe limitations exist with the application of protection methods available within literature for this application. To overcome these shortfalls, novel fault detection approaches are proposed and analysed. These approaches enable fault detection time targets to be met as well as aid with the effective integration of future circuit breaking technologies