A hernia frequently complicates abdominal stoma formation. The aetiology of parastomal herniation is claimed to be multi-factorial but currently only age and trephine diameter have been shown to independently predict its development. Open or laparoscopic repair of a symptomatic parastomal hernia is frequently challenging and is associated with unsatisfactory recurrence rates. As a result, many affected patients are managed non-operatively. Prevention of parastomal herniation by prophylactic mesh reinforcement of the stoma site is a new strategy that may reduce its incidence. Manual mesh implantation, however, is thought to increase the operating time and is considered cumbersome, particularly in laparoscopic surgery. As a result, routine reinforcement of the stoma site is not currently standard practice within the National Health Service. Thus, there is a need for a simple and quick technique for stoma formation which avoids creating an oversized defect and simultaneously reinforces the trephine with mesh. The aims of this thesis included: (i) understanding the aetiopathogenesis of parastomal herniation, assessing its impact on patients’ quality of life and examining the outcomes associated with current therapeutic strategies in order to find novel therapies that may lead to its prevention; (ii) assessing the safety, reproducibility and efficacy of the Stapled Mesh stomA Reinforcement Technique (SMART) in preventing parastomal herniation and (iii) investigating the contribution of the rectus abdominis muscle to the development of herniation. A detailed literature review of PubMed and Medline databases confirmed that stoma formation through the rectus muscle is complicated by parastomal herniation in 50%-80% of 4 cases. Surgeons have underestimated its impact on patients’ quality of life. There is no conclusive evidence that alternative techniques (e.g. extraperitoneal, lateral rectus abdominis positioned stoma) are superior. Open and laparoscopic parastomal hernia repair have similar recurrence rates up to 50%. Prophylactic reinforcement of the stoma trephine with mesh in the sublay or subperitoneal position is safe and appears to reduce the herniation rate but it is difficult laparoscopically and does not address the issue of trephine size when a defect <25mm is associated with a reduced herniation risk. The Stapled Mesh stomA Reinforcement Technique (SMART) obviates the technical issues associated with routine stoma formation and reinforcement. In a pilot study with patients at high risk for herniation, SMART was found to be safe and reproducible and reduced the herniation rate to 18%. Preliminary results of the international multicentre randomised controlled trial in all patients undergoing permanent stoma formation show that SMART reduces the herniation rate compared to the standard technique, without added morbidity and minimal impact on the operating time. A radiological study assessing the contribution of the rectus abdominis muscle into the development of parastomal herniation showed that the abdominal musculature undergoes postoperative changes consistent with atrophy with postoperative muscle density being higher in patients without parastomal herniation. In conclusion, at this moment in time, prophylactic mesh reinforcement should be offered to all patients undergoing elective permanent stoma formation. The SMART procedure has the potential to change current surgical practice. The contribution of the rectus muscle to the development of herniation warrants further research since improving muscle repair and regeneration may result in therapeutic benefits.

Epoxy coatings are currently the most popular corrosion protection mechanism for steel reinforcement in structural concrete. However, these coatings are easily damaged on worksites, negating their intended purpose. This study investigates self-healing coatings for steel reinforcement to introduce an autonomous healing mechanism for damaged coatings. Coatings were applied to steel coupons, intentionally damaged, and introduced to a corrosive environment via aerated salt-water tanks. Performance of the experimental coatings was evaluated qualitatively and quantitatively. Adhesion strength and effects of coating thickness were also studied. Results from coated steel coupons subjected to damage and submerged in salt-water aeration tanks exhibited improved corrosion resistance performance with self-healing coatings. However, self-healing coatings have comparable poor adhesion to the substrate as do conventional coatings. This paper shows preliminary results demonstrating the potential benefits of self-healing coatings for steel reinforcement and identifies numerous avenues for future research.

Reading interest is a significant predictor of reading achievement, with effects on both reading comprehension and vocabulary. We measured students’ interest in reading as an estimate of duration of observable reading using whole intervals of silent-reading time. In Experiment 1, we assessed associations among interest in reading (i.e., reinforcement value of reading) and the reading comprehension and vocabulary of 34 second-grade students. There were significant correlations between reading interest and these dependent measures. In Experiment 2, we simultaneously conducted a combined preintervention and postintervention design with multiple probe logic to test the effect of the establishment of a high interest in reading (i.e., conditioned reinforcement for reading) via a collaborative shared reading procedure with a teacher on reading comprehension and vocabulary. This procedure involved periods of reciprocal reading and related collaborative reading activities designed to increase students’ interest in reading. The establishment of a high interest in reading for 7 of the participants resulted in grade-level increases from 0.1 to 2.2 grades on various measures of reading achievement in less than 9 sessions (315 min). In Experiment 3, we implemented a combined small-n experimental-control simultaneous treatment design and a single-case multiple-probe design with multiple-probe logic. We tested and compared the effects of the establishment of conditioned reinforcement for reading, via the collaborative shared reading procedure with a teacher versus a peer, on participants’ gains in reading comprehension and vocabulary. All participants for whom conditioned reinforcement for reading was established in Experiment 3 (n = 7) demonstrated gains in reading achievement after a maximum of nine sessions (412 min), with grade-level increases between 0.2 and 2.5 on measures of reading comprehension and 0.3 to 3.1 on measures of vocabulary. Based on a comparison of the dependent variables included in both Experiments 2 and 3, the modified teacher-yoked collaborative shared reading procedure in Experiment 2 resulted in greatest relative average gains in reading achievement for participants who acquired conditioned reinforcement for reading (n = 3). However, the modified collaborative shared reading procedure with a peer required the least amount of teacher mediation and may be more viable for teachers. This trans-disciplinary effort proposes an account of motivation to read as conditioned reinforcement for reading content and its effects on reading achievement, with the educationally-significant goal of establishing reinforcers for continued learning.

One of the most significant challenges in the composite development field is to find a low-cost manufacturing route capable of producing large volumes of material. This thesis develops and characterises a potential avenue for addressing this, an induction furnace-based process. This process produced a composite of A357 matrix and 10% wt Dramix 3D 80/30 SL steel fibres. The method was evaluated by microstructural analysis and optimum casting parameters were approximated. The fibres were introduced to liquid A357 at 700°C and the composite was brought to a measured temperature of 650°C over not more than 120 seconds before being removed from the furnace and cooled. 10% wt was the ideal reinforcement ratio for this process. Characterising the tensile and compressive strength of the composite material, it reached a peak stress 130% higher than A357 produced under the same conditions, though the peak stresses were still 20% of the literature values for T6 tempered A357. This suggests the need for development of a temper which does not degrade the properties of the composite. 3-point bending tests and some tensile specimens also showed post-failure strength. Under dynamic loading, the composite showed a peak stress in excess of 100 MPa without reaching maximum compression under SHPB loading, and comparable performance to SiC-reinforced MMCs under ballistic testing. The linear decrease in work-hardening with increasing distance from the impact site shows shock and pressure-pulse dissipation properties, attributed to the difference in acoustic impedance between the matrix and the reinforcement.

This thesis comprehensively studies three questions. First of all, I use a unique set of institutional investor bids to examine the impact of personal experience on the behavior of institutional investors in an IPO market. I find that, when deciding to participate in future IPOs, institutions take into account initial returns of past IPOs in which they submitted bids more than IPOs which they merely observed. In addition, initial returns from past IPOs in which institutions’ bids were qualified for share allocation were given more consideration than IPOs for which unqualified bids were submitted. This phenomenon is consistent with reinforcement learning. I also find that institutions do not distinguish the returns that are derived from random events. Furthermore, institutions become more aggressive bidders after experiencing high returns in recent IPOs, conditional on personal participation or being qualified for share allocation in those IPOs. This bidding behavior provides additional evidence of reinforcement learning in IPO markets. Secondly, I merge the dataset of institutional investor bids with post-IPO institutional holdings data to examine whether institutional investors such as fund companies reveal their true valuations through bids in a unique quasi-bookbuilding IPO mechanism. I find that fund companies do truthfully disclose their private information via bids, despite these being without guaranteed compensation. My results contribute to the existing literature by providing new evidence on the information compensation theory and have implications for the IPO mechanism design. Finally, I explore the impact on firm valuation of going public abroad using a sample of 136 Chinese firms that conducted IPOs in the US during the period of 1999-2012. I find that US-listed Chinese firms have higher price multiples and experience less underpricing than their domestic-listed peers. The valuation premium stays consistent when a firm’s characteristics and listing cost are being controlled. These findings are consistent with the theories of foreign listing. Moreover, I find that high-tech Chinese firms with a high growth rate but low profitability are more likely to issue shares in the US, particularly for specific industries such as semiconductors, software and online business services. This industry clustering is interpreted as an incentive to access foreign expertise through listing abroad.

Generally human titration performance under schedules of reinforcement has not been investigated. In an attempt to examine the variables which control titration, an interlocking progressive-ratio schedule was devised. Under an interlocking progressive-ratio schedule, the number of responses required for reinforcement increases by a constant (the increment value) after every ratio, but during each ratio the response requirement can be lowered (the decrement value) by emitting pauses of a specified duration (the stepdown duration). The first experiment sought to determine if children would titrate when exposed to interlocking progressive-ratio schedules. Although three of the four subjects did not show evidence of titration initially, through a series of manipulations all came under schedule control. Experiment 2 was conducted to determine the effects of a series of increment value manipulations on the level of titration. The series of increment values was tested under large and small decrement conditions. The results showed that increment value was an important determiner of titration level only when the decrement value was small. When the decrement value was large, changes in increment value had no effect upon titration. In Experiment 3 the effects of a series of decrement manipulations on titration level were examined. The decrement manipulations were investigated under two increment values. The results indicated that as the decrement value was decreased the titration level tended to increase under both increment conditions. In all of the experiments, rate of responding, pausing, titration variability, and patterns of responding were examined. Generally rate of responding, pausing, and response patterning were found to be related to changes in increment and decrement values. Titration variability showed no systematic changes across manipulations. Analysis of subjects' behavior in terms of preference indicated that the subjects tended to minimize number of responses rather than maximize reinforcement frequency. Subjects would pause to bring down the response requirement, and thus increase the time between reinforcements, rather than emit responses on a lever, which would have resulted in more reinforcements per unit of time.

Animals performing on simple fixed-ratio (FR) schedules vi typically pause after reinforcement delivery. The present study demonstrated systematic control of pause length in multiple fixed ratio schedules by manipulating FR size and reinforcement magnitude. In Experiment I, two adult male rabbits were stabilized on an alternating, two component, multiple FR 10 FR 10 schedule. Different colored lights were correlated with both FR components. Stability was determined and mean pause lengths were calculated as one FR component was increased in size until the schedule was FR 10 FR 50. Pausing was longer before the large FR component and was positively correlated with increases in FR size. Schedule and stimulus control were demonstrated by randomizing the order of FR presentations and by reversing the colored lights previously correlated with either the small or large FR components. Existing pause differentials were not disrupted under the light reversal or random conditions. In Experiment II, the same rabbits were stabilized at mult FR 10 FR 30 with 1/2 cc of water delivered after each component. In subsequent conditions the magnitude of reinforcement (cc's of water) delivered at the completion of the large FR component, was systematically shifted from 4 cc, to 3 cc, 2 cc, 1 cc and finally back to 1/2 cc. Pausing before the large FR was found to be inversely related to the magnitude of reinforcement delivered in that component. Clearly the animals in this experiment discriminated upcoming schedule conditions and paused relative to FR size and reinforcement magnitude. Hence, it is proper to point out that the term "post-reinforcement pause" is a misnomer since it incorrectly implies a functional relation between pause length and prior schedule conditions.

The purpose of the present laboratory study was to investigate the relative effects of sharing and nonsharing peer and adult models on the facilitation of prosocial behaviors with and without reinforcement to the model. One hundred and sixty second and third grade children served as subjects and were randomly assigned to six treatment groups and one control group. For replication purposes, half of the subjects participated in each condition prior to the second half doing so. Children in the treatment groups viewed videotaped sequences portraying both a male and female model sharing or not sharing tokens with poor children. Models were either peers or adults. Sharing was either reinforced by praise from an adult or not reinforced; nonsharing was not reinforced. Children in the control group viewed an entertainment program devoid of prosocial or antisocial content. All children received instructions with respect to the acquisition and distribution of tokens which were exchangeable for prizes at the end of the session. Prosocial behaviors were· assessed following the videotaped sequences and included token donations, volunteering of work, and offering help following a staged accident. Children viewing nonsharing and nonreinforced peers had lower token donations than children in other treatment groups and the control group. Although not statistically significant findings, children who viewed peer models exhibiting prosocial behaviors that were reinforced had greater token donations and tended to help in the staged accident more than children in other treatment groups. No differences were found between treatment groups with respect to volunteering work. More children provided help in a staged accident when they had observed sharing peers who were reinforced than children in other conditions. However when children observed nonsharing and nonreinforced adults, they displayed a lower incidence of helping. Vicarious reinforcement produced greater, though not statistically significant, token donations as compared with the absence of reinforcement in both adult and peer treatment conditions. The correlations among donations, volunteering, and helping were found to be low. Modeling in combination with reinforcement of the model was not sufficient to increase prosocial behaviors significantly beyond the performance of a control group. The contribution of peer modeling to the facilitation of prosocial behaviors in the early elementary grades appears slight. Nevertheless, peer models were especially influential in inhibiting prosocial behaviors by the modeling of antisocial responses. The observation of reinforcement contingencies applied to models only slightly increased prosocial behaviors and can not be considered a potent variable in this behavior domain.

Autism Spectrum Disorder is a developmental disability characterized by social, behavioral, and communicative impairments. A primary characteristic of Autism includes impairment in social skills. Along the same lines, praise, defined as approval or admiration, does not always function as a reinforcer for this population. One way to address the absence of a reinforcement effect for praise is to condition praise as a reinforcer. The literature on conditioned reinforcement encompasses many procedural variations that have been shown to increase the reinforcing value of neutral stimuli. One such variation relatively new to the conditioned reinforcement literature includes observational conditioning. With observational conditioning, initially neutral stimulus are established as reinforcers through observation of others receiving an initially neural stimulus, contingent on some response, while the same neutral stimulus is restricted to the observer for engagement the same response. Few component analyses of observational conditioning procedures have been conducted. Identification of its key aspects and further clarification of its generality will improve understanding of the effect and lead to more reliable clinical endpoints. Given this, and the need for procedures focused on conditioning praise as a reinforcer for individuals with Autism, the purpose of the current proposal was twofold. The purpose of Study 1 was to compare the effects of the observational conditioning procedure to observational conditioning plus response restriction in children diagnosed with Autism. The purpose of Study 2 was to assess the effects of observational conditioning plus response restriction to condition praise as a reinforcer in children diagnosed with Autism.

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