In a nuclear reactor, delayed neutrons play a critical role in sustaining a controllable chain reaction. Delayed neutron’s relative yields and decay constants are very important for modeling reactivity control and have been studied for decades. Researchers have tried different experimental and numerical methods to assess these delayed neutron parameters. The reported parameter values vary widely, much more than the small statistical errors reported with these parameters. Interestingly, the reported parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical methods used to extract the delayed neutron parameter from the measured data, including Matrix Inverse, Levenberg-Marquardt, and Quasi-Newton methods, were studied extensively using simulated delayed neutron data. This simulated data was Poisson distributed around Keepin’s theoretical data. The extraction methods produced totally different results for the same data set, and some of the above numerical methods could not even find solutions for some data sets. Further investigation found that ill-conditioned matrices in the objective function were the reason for the inconsistent results. To find a reasonable solution with small variation, a regularization parameter was introduced using a numerical method called Ridge Regression. The results from the Ridge Regression method, in terms of goodness of fit to the data, were good and often better than the other methods. Due to the introduction of a regularization number in the algorithm, the fitted result contains a small additional bias, but this method can guarantee convergence no matter how large the coefficient matrix condition number. Both saturation and pulse modes were simulated to focus on different groups. Some of the factors that affect the solution stability were investigated including initial count rate, sample flight time, initial guess values. Finally, because comparing reported delayed neutron parameters among different experiments is useless to determine if their data actually differs, methods are proposed that can be used to compare the delayed neutron data sets.

This thesis demonstrates the performance of Probabilistic Early Response TCP (PERT), a new TCP congestion control, for video streaming. As a delay based protocol, it measures the delay at the end host and adjusts the congestion window accordingly. Our experiments show that PERT improves video delivery performance by decreasing the fraction of packets delivered late. Furthermore, our Linux live streaming test indicates that PERT is able to reduce the playback glitches, when high resolution video is delivered over a link with non-zero packet loss. In order to operate PERT at higher thoughputs, we design PERT to work with Acknowledgement (ACK) coalescing at the receiver. ACK coalescing makes data transfers burstier and makes it hard to estimate delays accurately. We apply TCP pacing to fix this issue, and validate its effectiveness in the aspects of throughput, packet loss and fairness. Our experiment results also show that PERT with Delayed ACK and Pacing is more friendly, and therefore more suitable when multiple traffic flows are competing for limited bottleneck bandwidth or sharing the same router buffer.

Objective Healthcare system now, with global budget payment, is facing an increasing challenge mainly due to patient oriented environment, more demand for service quality and organizational re-arrangement. Also due to the high cost of personalle and equipments in the operation room , it is quite important to maintain the high efficiency of management to encompass high volume of surgeries. Staffing and scheduling is the most important issue in the management of the operating room and has direct impact on the operational efficiency, cost and revenue. The purpose of this study is to investigate the influence of staffing and scheduling of the operating room on its efficiency. How we control the sum of the patients requiring operation under present circumstances lies on whether or not we have efficient management of the operation room. The most important part among it depends on the ability of schedule arrangement, which directly influence the performance audit and cost. Materials and Methods:The purpose of this study is to discuss the impact of schedule arrangement on cost in the operation room of one medical center. Retro spective descriptive design. Those first operations performed from July 1st, 2003 to June 30th, 2004 were collected into the controlled group while those performed from July 1st, 2004 to June 30th, 2005 were gathered into the experimental group. Indicators of the effect including the sum of the patients receiving operation, the utilization rate of the operation room, the cancellation rate of scheduled operation, the number of overtime nursing staff and overtime payment, the delayed rate and time of the first operation. We use ANOVA, x2 test, multiple logistic regression and t test to analyze these data. We will discuss issues as the followings to smooth our operation schedule: the arrangement of the fist operation by program manager, setting up a flow chart for nursing staff while admitting the patients, establishing a check-in flow chart for patients of out-patient department and deployment of pageboys. Results: The data showed that the incidence of delaying surgery were decreased by 8.4% in the experiment group as compared to the control group. The operation room occupation rate increased to 84.3% in control group, as compared to 78.25% in experiment group. There is 0.76% decrease in the rate of canceling operation schedule . The number of nursing staff who worked overtime and the overtime payment decreased significantly. The time needed from patients entering operation room to the operation began also decreased significantly. The rate of delaying the first scheduled operation decreased from 52.8% to 12.3%. Conclusion: Operation room managers, leader in department of surgery, and hospital managers could take our results as reference in improving efficiency and decreasing cost.

The ability to quickly and accurately quantify fissile constituents in bulk materials remains essential to many aspects of nuclear forensics and for safeguarding nuclear materials and operations. This often entails the analysis of trace quantities of nuclear debris or effluents, and typically requires bulk sample digestion followed by actinide separation and mass spectrometry. Because destructive methods are time and labor intensive, efforts have been made to develop alternative nondestructive methods for this type of analysis. This work, performed at Oak Ridge National Laboratory at the High Flux Isotope Reactor (HFIR), seeks to utilize delayed neutron activation analysis on samples of interest containing multiple fissile constituents. Based on the variances in the fission product yields of individual fissile nuclides, this work utilizes methods of linear regression to derive a technique that allows for such analysis, forgoing chemical separation and using only a single irradiation and counting step. / text

Since 2006, research funded by the Texas Department of Transportation (TxDOT) has evaluated the use of coatings and sealers for mitigating expansion due to alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF) in hardened concrete. The report herein includes a project summary of previous work in Phase I, led by Racheal Lute (2008) and Charles Rust (2009). The Phase II research, described in this thesis, established concrete exposure blocks and NCHRP 244 Series II testing as the cornerstones of characterizing coating effectiveness. The studies assessed coating system performance by examining the contribution of steel reinforcement, the effects of aggregate reactivity, the size limitations of treatments, and the impact of painted concrete substrates. Lastly, this thesis describes the preliminary results of a field study site of columns supporting a flyover, and a concrete exposure block site in Houston, Texas. Overall, the results are encouraging as several coatings have reduced expansion by lowering internal relative humidity.

Alkali-silica reaction (ASR) and delayed ettringite formation (DEF) deterioration have been a problem for the concrete infrastructure in the state of Texas and around the world in recent decades. A great deal of research into the causes and mechanisms of the deterioration has helped to prevent the formation of ASR and DEF in new construction, but the evaluation and maintenance of existing structures remains a problem. The goal of this research is to investigate the use of several nondestructive testing (NDT) methods to evaluate the level of ASR and DEF deterioration in a structural element. Based on the results, recommendations are made as to which NDT methods have the most potential to be incorporated into the evaluation process. / text

We have constructed a response adaptive clinical trial to treat patients sequentially in order to maximize the total survival time of all patients. Typically the response adaptive design is based on the urn models or on sequential estimation procedures, but we used a bandit process in this dissertation. The objective of a bandit process is to optimize a measure of sequential selections from several treatments. Each treatment consist of a sequence of conditionally independent and identically distributed random variables, and some of these treatment have unknown distribution functions. For the purpose of this clinical trial, we are focusing on the bandit process with delayed response. These responses are lifetime variables which may be censored upon their observations. Following the Bayesian approach and dynamic programming technique, we formulated a controlled stochastic dynamic model. In addition, we used an example to illustrate the possible application of the main results as well as "R" to implement a model simulation.

The allylic bromide functionality within brominated poly(isobutylene-co-isoprene), or BIIR, alkylates primary amines repeatedly to generate thermoset products at reaction rates that are too fast to support commercial rubber processing operations. The objective of this work was to assess the utility of latent N-nucleophiles as curatives and modification reagents for BIIR. Ideally, BIIR formulations containing these latent amines would not cure at standard compound mixing temperatures, but support high crosslinking rates and yields upon heating to conventional vulcanization temperatures. Carbon dioxide-derived salts of ammonia, including (NH4)2CO3, (NH4)HCO3 and (NH4)H2NCO2, can be mixed with BIIR without incurring crosslinking at temperatures below 100oC, but they generate adequate crosslink yields upon heating to 160oC. The corresponding CO2-derived salts of primary amines decompose below 100oC and, therefore, do not provide adequate scorch protection when mixed with BIIR. Latency was conferred on primary amines using imine derivatives, in particular N-alkylbenzaldimine and its substituted analogues. These latent curatives are activated by hydrolysis, thereby providing a means of controlling active nucleophile concentrations, and minimizing crosslinking activity at 100oC without impacting negatively on cure rates at 160oC. The scorch problems generated by primary amines extend to BIIR cure formulations employing conventional sulfur and ZnO curatives. In contrast, imine analogues are shown to provide low temperature scorch stability without impacting negatively on high temperature cure rates and extents. / Thesis (Master, Chemical Engineering) -- Queen's University, 2010-02-01 15:18:16.004

Following vestibular schwannoma excision, a subset of cases has been reported in which hearing is present immediately after surgery, but is lost in the early postoperative period. Such cases have rarely been reported, and the postoperative audiological data collected from patients in these cases lacks the time resolution necessary to determine the pathophysiological mechanism responsible for the pattern of hearing loss. The present study aimed to more clearly define delayed hearing loss by collecting detailed data documenting changes in behavioural and electrophysiological auditory responses following vestibular schwannoma surgery. In particular, we aimed to use this data to determine the time course of changes in auditory function and to identify whether the site of impairment was cochlear or neural. Preoperative and daily postoperative monitoring of auditory function was performed in 19 patients undergoing vestibular schwannoma excision via the retrosigmoid approach at Christchurch Public Hospital. The pre- and postoperative assessment battery included pure-tone and speech audiometry, tympanometry, tone decay, distortion product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR) measurement. Intraoperative ABR was performed in four cases in which clear preoperative waveforms were present. Transtympanic electrocochleography (ECochG) was carried out if wave I was lost in the early postoperative period. Thirteen of the 19 patients suffered immediate anacusis following surgery and six had measurable hearing postoperatively. The behavioural and electrophysiological data collected in each case is discussed with regard to the likely pathophysiology of pre- and postoperative hearing loss. No patients demonstrated behavioural evidence of delayed hearing loss, however a gradual deterioration of ABR in the early postoperative period was observed in Case 16. ECochG and DPOAEs in this case indicated the presence of cochlear function although the patient presented with immediate postoperative anacusis in the ipsilateral ear. These results are consistent with postoperative retrograde degeneration of the cochlear nerve.

Newborn morbidity and mortality remains high despite a remarkable decline in the infant mortality and under five mortality rates in Nepal over the last decade (1996-2006). Research shows that newborns’ health outcome is associated with maternal and other factors. This study was designed to understand the factors that have an impact on three good newborn care practices: safe cord cutting, early breastfeeding and delayed bathing. The study used the interview data of 815 married women aged 15-49 years who delivered a live baby between February 2008 and February 2009, collected for the baseline survey of the Community-Based Maternal and Newborn Health program implemented in the Sindhuli district of Nepal. The mean age of the sample women was 26 years. Two-thirds of them were from disadvantaged indigenous caste/ethnicity groups, about 70% were uneducated and the majority were poor. Safe cord cutting, early breastfeeding and delayed bathing practices were studied for 803, 810 and 812 women respectively and 70.7%, 46.7%, and 16.6% of the eligible samples demonstrated the practices respectively. The logistic regression method was used to examine the association of independent factors with the outcome variables. Social gradient was found to be associated with all three practices. Rich women were more likely to demonstrate good practices and bearing a child at the prime age (20-34 years) was likely to result in safe cord cutting. Disadvantaged indigenous and ‘other’ caste/ethnicity women demonstrated unsafe cord cutting practices and dalit caste/ethnicity women demonstrated poor bathing practices. Maternal knowledge also emerged as a strong predictor of early breastfeeding and delayed bathing practices. Antenatal care from a SBA determined good breastfeeding and advice from a FCHV determined good bathing practices. The results showed that the uptake of antenatal and delivery services from a skilled birth attendant is unacceptably low in rural Nepal, which is a challenge for meeting the millennium development goals. The study recommends programmes for improving economic status as a key to improving newborn care practices. As the vast majority of the deliveries are still assisted by traditional birth attendants; including them in maternal health programmes is crucial. Increasing women’s access to a skilled birth attendant and boosting the spirit of the FCHVs to increase their efficiency is also recommended. Future research on newborn health should focus on identifying other determinants of newborn care practices and survival. Qualitative studies to understand the cultural perspectives of newborn care practices are also recommended.