We consider the scheduling problem of minimizing the average weighted completion time of n jobs with release dates on a single machine. We first study two linear programming relaxations of the problem, one based on a time-indexed formulation, the other on a completiontime formulation. We show their equivalence by proving that a O(n log n) greedy algorithm leads to optimal solutions to both relaxations. The proof relies on the notion of mean busy times of jobs, a concept which enhances our understanding of these LP relaxations. Based on the greedy solution, we describe two simple randomized approximation algorithms, which are guaranteed to deliver feasible schedules with expected objective value within factors of 1.7451 and 1.6853, respectively, of the optimum. They are based on the concept of common and independent a-points, respectively. The analysis implies in particular that the worst-case relative error of the LP relaxations is at most 1.6853, and we provide instances showing that it is at least e/(e - 1) 1.5819. Both algorithms may be derandomized, their deterministic versions running in O(n2 ) time. The randomized algorithms also apply to the on-line setting, in which jobs arrive dynamically over time and one must decide which job to process without knowledge of jobs that will be released afterwards.

A new method for multi-objective optimization of linear and mixed programs based on Lagrange multiplier methods is developed. The method resembles, but is distinct from, objective function weighting and goal programming methods. A subgradient optimization algorithm for selecting the multipliers is presented and analyzed. The method is illustrated by its application to a model for determining the weekly re-distribution of railroad cars from excess supply areas to excess demand areas, and to a model for balancing cost minimization against order completion requirements for a dynamic lot size model.

Prior work has provided support that women with breast cancer are hyper-responsive to stressful challenges and that Cognitive-Behavioral Stress Management (CBSM) interventions can lead to reductions in cortisol, a measure of physiological stress. It may follow that breast cancer patients would show decreases in cortisol levels if they are taught stress management techniques. The purpose of this study was to investigate post-intervention psychosocial processes (i.e., participants' perceptions of achieved specific skills targeted by CBSM and non-specific changes associated with the group experience) that may explain intervention-related changes in cortisol among a sample of women as they moved through medical treatment for non-metastatic breast cancer. It was hypothesized that (a) women receiving a 10-week, group-based stress management intervention during ongoing medical treatment for breast cancer would show reductions in late afternoon serum cortisol levels and (b) perceived ability to implement stress management skills or other experiences gained in the supportive group environment may explain changes in cortisol. Participants (N = 128) were women recruited 4-8 weeks post-surgery for non-metastatic breast cancer. Women were randomly assigned to receive either the 10-week CBSM intervention (N = 63) or a one-day psychoeducational seminar (n = 65). The intervention aimed to teach relaxation, cognitive restructuring, and interpersonal skills. Participants were assessed at study entry, 6 month follow-up (i.e., 3 months post-intervention) and 12 month follow-up (i.e., 6 months post-intervention). Latent Growth Curve Modeling (LGM) was used to test for differential effects of study condition on change over time in cortisol and the effects of specific and non-specific group processes on change in cortisol. Results indicated there was a significant effect of study condition on change over time in cortisol, relaxation skills, and assertiveness skills. There were not significant relationships between changes in cortisol and any of the components analyzed and mediation was not established using LGM. There was, however, a significant association between changes in an item that assessed cognitive restructuring and cortisol. Exploratory analyses of lagged (Time 2 controlling for Time 1) psychosocial processes mediating (Time 3 controlling for Time 2) cortisol changes were then conducted. Results indicated that condition's effect on cortisol approached significance and condition had a significant effect on the muscle relaxation component and cognitive restructuring item. Furthermore, there was evidence that intervention-related changes in confidence about using muscle relaxation and cognitive restructuring may help explain decreases in cortisol levels among this sample of women. Overall, this study demonstrated that a 10-week, CBSM intervention was associated with decreased cortisol levels and increased relaxation and assertiveness skills. Furthermore, there was a strong relationship between changes in cognitive restructuring and cortisol. Future research should investigate how changes in cortisol may be related to health behaviors and health outcomes among breast cancer patients.

In modern telecommunications, there is a need for quadrature oscillator exhibiting an accurate and stable phase relation. For example, identical two mutually coupled relaxation oscillator can generate identical quadrature signals, and have extremely accurate and stable phase relation. In this thesis, we propose a current cross-coupled relaxation oscillator with quadrature outputs. The oscillator consists of two identical current relaxation oscillators and a current comparator. The circuit takes the high frequency advantage of current mode circuit. Because of cross-coupled feedback, this oscillator have highly accurate ( <1¢X) and stable quadrature outputs. It is implemented by using TSMC 0.35£gm 2P4M CMOS technology.

The purpose of this research was to describe the use of autohypnosis as a psychotherapeutic intervention with hearing impaired college students specific to four clinical questions: A. Are hearing impaired persons susceptible to hypnosis? B. Can written hypnotic induction be used to introduce hearing impaired persons to relaxation technics? C. Can hearing impaired persons use autohypnosis to achieve a state of relaxation? D. While in a hypnotic state of relaxation can a hearing impaired subject engage in a predetermined fantasy?Eight oral hearing impaired undergraduates, between 18-22 years old, for eight consecutive days completed questionnaires germane to their use of hypnosis. Sixty four questionnaires were submitted to data analysis. Each subject's response as to perceived state of hypnosis was cross-tabulated with: five nonhypnotic state indicators;the amount of time displacement reported per hypnotic session; and three outcome indicators of subject having engaged in predetermined fantasy. The total absolute frequency of incidence(s) of hypnosis having occurred was calculated to be 49 out of 64 reported attempts. The relative frequency percentage was calculated as 75.6% which was interpreted as a descriptive indicator that oral hearing impaired persons utilizing a written autohypnotic technic are susceptible to and can induce, for self, a hypnotic state of relaxation. Additionally it was interpreted that for oral hearing impaired persons the induction technic does not have to deviate extensively from the traditional autohypnotic technic(s) used by (for) aural populations.The findings of this study were limited to the described sample, conditions, time frame and measurement instrument. However, from the 75.6% positive response to the clinical questions it was inferred that the overall outcome of the study was positive. Future research might affirm the appropriateness of autohypnotic relaxation therapy as a possible service to the deaf consumer of psychological counseling.

Spinal cord injury (SCI) leads to axonal damage and limits the ability of the brain to communicate with the rest of the body. Several bioengineered approaches have been developed for the recovery of SCI. Among these techniques, degradable guidance tubes have shown promising results. However, design of nerve guide tubes requires several design considerations and has been a significant challenge. To assess the efficacy of a prototypical implanted nerve guide tubes, it is essential to perform continuous monitoring. In this respect, magnetic resonance imaging (MRI) is one of the most reliable imaging techniques as it offers the ability to achieve extraordinary high temporal and spatial resolution in addition to its non-invasive features. In spite of the excellent image quality of non-enhanced MRI various types of contrast agents have been developed to further enhance the contrast and allow improved visualization. The MRI contrast agents principally work by shortening the T1 or T2 relaxation times of protons located nearby. The presented study was intended to evaluate the in vitro degradation of the nerve guide tubes made of poly (lactic-co-glycolic acid) (PLGA). PLGA tubes incorporated with different concentrations of superparamagnetic iron oxide (SPIO) were scanned by MRI 3T on weekly basis during the degradation period. Spin-echo (SE) sequence with various echo times (TEs) ranged from 13.3 to 314.4 msec was applied. T2 mapping was computed using in-house algorithm developed in Matlab. Least square fit was used to find the slope of the decay curve by plotting log intensity on the y-axis and echo time on the x-axis. The average T2 values were calculated. Mass loss and water uptake of the degrading tubes were also measured weekly. Moreover, the micro-structural changes of the tubes were investigated using the scanning electron microscope (SEM). The MRI results showed that the concentration of SPIO affects the signal intensity of the T2 weighted images reducing the T2 relaxation time value. Accordingly, a linear correlation between SPIO concentration and T2 relaxation time was found. At the beginning of degradation, the SPIO nanoparticles were trapped within the polymeric network. Therefore, water penetration was the predominant factor affecting the T2 relaxation times. At week 5, a significant mass loss was observed. From this stage onwards, the trapped SPIO were released from the polymeric network increasing T2 relaxation time dramatically. According to SEM images, the size of the pores in PLGA guide tubes was increased with the degradation. Approaching the end of degradation, shrinkage of the tubes was observed and the degraded nerve guide tubes were shown to be collapsed. Similar shape variation was observed in T2 weighted MR images. In summary, this study provided an approach to non-invasive monitoring of degradation behavior of nerve guide tubes using contrast enhancement. The developed technique is of great importance since it opened an insight to non-invasive monitoring of tissue engineered scaffolds for in vivo studies.

This thesis explores three consolidation problems derived from the daily operations of major international airfreight forwarders. First, we study the freight forwarder's unsplittable shipment planning problem in an airfreight forwarding network where a set of cargo shipments have to be transported to given destinations. We provide mixed integer programming formulations that use piecewise-linear cargo rates and account for volume and weight constraints, flight departure/arrival times, as well as shipment-ready times. After exploring the solution of such models using CPLEX, we devise two solution methodologies to handle large problem sizes. The first is based on Lagrangian relaxation, where the problems decompose into a set of knapsack problems and a set of network flow problems. The second is a local branching heuristic that combines branching ideas and local search. The two approaches show promising results in providing good quality heuristic solutions within reasonable computational times, for difficult and large shipment consolidation problems. Second, we further explore the freight forwarder's shipment planning problem with a different type of discount structure - the system-wide discount. The forwarder's cost associated with one flight depends not only on the quantity of freight assigned to that flight, but also on the total freight assigned to other flights operated by the same carrier. We propose a multi-commodity flow formulation that takes shipment volume and over-declaration into account, and solve it through a Lagrangian relaxation approach. We also model the "double-discount" scheme that incorporates both the common flight-leg discount (the one used in the unsplittable shipment problem) and the system-wide discount offered by cargo airlines. Finally, we focus on palletized loading using unit loading devices (ULDs) with pivots, which is different from what we assumed in the previous two research problems. In the international air cargo business, shipments are usually consolidated into containers; those are the ULDs. A ULD is charged depending on whether the total weight exceeds a certain threshold, called the pivot weight. Shipments are charged the under-pivot rate up to the pivot weight. Additional weight is charged at the over-pivot rate. This scheme is adopted for safety reasons to avoid the ULD overloading. We propose three solution methodologies for the air-cargo consolidation problem under the pivot-weight (ACPW), namely: an exact solution approach based on branch-and-price, a best fit decreasing loading heuristic, and an extended local branching. We found superior computational performance with a combination of the multi-level variables and a relaxation-induced neighborhood search for local branching.

This thesis is based on observations of the physical properties of wheat flour dough using ultrasonic measurements. Three frequency ranges were used in the study, low frequencies (near 40 kHz), intermediate frequencies (1 to 5 MHz, where bubble resonance effects are apparent), and high frequencies (near 20 MHz). Doughs mixed under different head space air pressures, from vacuum to atmospheric pressure, as well as under nitrogen, were studied at low frequency to investigate their relaxation behavior. Subsamples from ambient dough and vacuum dough displayed differences in the dependence of velocity and attenuation on time after compression, but no post mixing relaxation effect was apparent. A critical headspace pressure of approximately 0.16 atmospheres determined whether vacuum-like or ambient-like relaxation was observed. A peak in attenuation and changes in ultrasonic velocity were observed around the bubble resonance frequency, and these ultrasonic parameters changed substantially as a function of time. A bubble resonance model was used to interpret the results around the bubble resonance frequency, and bubble size distributions were estimated for ambient and vacuum dough from the ultrasonic data. For the high frequency range, a molecular relaxation model was used to interpret the results. Different fast relaxation times were observed for ambient dough (5 ns) and vacuum dough (1 ns). This relaxation time may be associated with conformational rearrangements in glutenin inside the dough matrix. These experiments have enabled dough relaxation to be probed over a very wide range of time scales (from ns to hours), and will lead to a better understanding of the role of dough matrix and gas cell effects on the physical properties of wheat flour doughs. / October 2007

No description available.

Abstract Aim: The aim of this study was to examine junior and first year senior athletes’ experiences and perceived effects of flotation-REST, including both the immediate response and experiences over time. Method: Semi-structured interviews were conducted with six elite track and field athletes (five female and one male), aged 17-23 years, who were purposefully sampled and had used flotation-REST two to six times. They were each interviewed on two occasions; once directly following a floating session and later a second interview concerning the overall experience. The interview transcripts were analyzed using Interpretative Phenomenological Analysis (Smith, 1996). Results: From the analysis four themes emerged: Meaning of Flotation-REST, Experiences during Flotation-REST, Perceived Effects of Flotation-REST, and Views on Flotation-REST. Flotation-REST became a learning opportunity concerning relaxation for all athletes and three of them reported that it raised their awareness of the importance of relaxation and psychological skills training. For five athletes the floating sessions also became a breather in the daily life. The floating sessions were perceived as pleasant and relaxing. Three athletes experienced a lot of thoughts in the tank and five of them fell asleep at least twice. After flotation-REST five athletes reported experiencing less stress and an overall increase in well-being as well as feeling calmer and more energized for one or two days, although they were physically tired at practice immediately following a floating session. Being in a better mood and placing fewer demands on themselves as well as feeling more optimistic and present were also mentioned as perceived effects. The results showed more and longer-lasting psychological effects than physiological. The sixth athlete did not experience any special effects, nor did he experience stress in his daily life and sport performance, as opposed to the others. Conclusions: The study shows the potential of flotation-REST as a technique for health promotion and also as a method for stress management. Further, as the results revealed raised awareness, flotation-REST could be valuable together with other psychological skills training techniques, mindfulness and the physical training. However, considering the differences in the athletes’ perceived effects of flotation-REST, it indicates the importance of further research on the topic.