Efficient Control in Multistage Stochastic Optimization Problem

AMS subject classification: 90C31, 90A09, 49K15, 49L20.

Fourth-root summation of contrast over area:no end in sight when spatially inhomogeneous sensitivity is compensated by a witch's hat

Measurements of area summation for luminance-modulated stimuli are typically confounded by variations in sensitivity across the retina. Recently we conducted a detailed analysis of sensitivity across the visual field (Baldwin et al, 2012) and found it to be well-described by a bilinear “witch’s hat” function: sensitivity declines rapidly over the first 8 cycles or so, more gently thereafter. Here we multiplied luminance-modulated stimuli (4 c/deg gratings and “Swiss cheeses”) by the inverse of the witch’s hat function to compensate for the inhomogeneity. This revealed summation functions that were straight lines (on double log axes) with a slope of -1/4 extending to ≥33 cycles, demonstrating fourth-root summation of contrast over a wider area than has previously been reported for the central retina. Fourth-root summation is typically attributed to probability summation, but recent studies have rejected that interpretation in favour of a noisy energy model that performs local square-law transduction of the signal, adds noise at each location of the target and then sums over signal area. Modelling shows our results to be consistent with a wide field application of such a contrast integrator. We reject a probability summation model, a quadratic model and a matched template model of our results under the assumptions of signal detection theory. We also reject the high threshold theory of contrast detection under the assumption of probability summation over area.

Semi-Symmetric Algebras: General Constructions. Part II

2000 Mathematics Subject Classification: 15A69, 15A78.

Retinal arteriolar diameter response to flicker light provocation - A useful marker for risk stratification in cardiovascular disease?

Purpose: To to evaluate the benefit of bilinear and linear fitting to characterize the retinal vessel dilation to flicker light stimulation for the purpose of risk stratification in cardiovascular disease. Methods: Forty-five patients (15 with coronary artery disease (CAD), 15 with Diabetes Mellitus (DM) and 15 with CAD and DM) all underwent contact tonometry, digital blood pressure measurement, fundus photography, retinal vessel oximetry, static retinal vessel analysis and continous retinal diameter assessment using the retinal vessel analyser (and flicker light provocation). In addition we measured blood glucose (HbA1c) and keratinin levels in DM patients. Results: With increased severity of cardiovascular disease a more linear reaction profile of retinal arteriolar diameter to flicker light provocation can be observed. Conclusion: Absolute values of vessel dilation provide only limited information on the state of retinal arteriolar dilatory response to flicker light. The approach of bilinear fitting takes into account the immediate response to flicker light provocation as well as the maintained dilatory capacity during prolonged stimulation. Individuals with cardiovascular disease however show a largely linear reaction profile indicating an impairment of the initial rapid dilatory response as usually observed in healty individuals

Using accreditation criteria for collaborative quality enhancement

This paper describes a process to enhance the quality of higher education. At the heart of the process is a cross-sparring collaborative model, whereby institutions are critical friends. This is based on a prior self-evaluation, where the institution / programme identifies quality criteria it wants to improve. Part of the process is to ensure the documentation of best practices so that they can be shared with others in a so called market place. Linking the best practices to a criterion makes them searchable on a large scale. Optimal pairings of institutions can then take place for the cross-sparring activities.

The acculturation of middle income Hispanic households

Research on the consumer behavior of the Hispanic population has recently attracted the attention of marketing practitioners as well as researchers. This study's purpose was to develop a model and scales to examine the acculturation process of Hispanic consumers with income levels of $35,000 and above, and its effects on their consumer behavior. The proposed model defined acculturation as a bilinear and multidimensional change process, measuring consumers' selective change process in four dimensions: language preference, Hispanic identification, American identification, and familism. A national sample of 653 consumers was analyzed. The scales developed for testing the model showed good to high internal consistency and adequate concurrent validity. According to the results, consumers' contact with Hispanic and Anglo acculturation agents generates change or reinforces consumers' language preferences. Language preference fully mediates the effects of the agents on consumers' American identification and familism; however, the effects of the acculturation agents on Hispanic identification are only partially mediated by individuals' language preference change. It was proposed that the acculturation process would have an effect on consumers' brand loyalty, attitudes towards high quality and prestigious brands, purchase frequency, and savings allocation for their children. Given the lack of significant differences between Hispanic and Anglo consumers and among Hispanic generations, only savings allocation for children's future was studied intensively. According to these results, Hispanic consumers' savings for their children is affected by consumers' language preference through their ethnic identification and familism. No moderating effects were found for consumers' gender, age, and country of origin, suggesting that individual differences do not affect consumers' acculturation process. Additionally, the effects of familism were tested among ethnic groups. The results suggest not only that familism discriminates among Hispanic and Anglo consumers, but also is a significant predictor of consumers' brand loyalty, brand quality attitudes, and savings allocation. Three acculturation segments were obtained through cluster analysis: bicultural, high acculturation, and low acculturation groups, supporting the biculturalism proposition. ^

Analysis of Heterokaryon Formation in Fusarium oxysporum f. sp. cubense.

Fusarium oxysporum forma specialis cubense is a soilborne phytopathogen that infects banana. The true evolutionary identity of this so called species, Fusarium oxysporum, is still unknown. Many techniques have been applied in order to gain insight for the observed genetic diversity of this species. The current classification system is based on vegetative compatibility groups (VCG's). Vegetative compatibility is a self non-self recognition system in which only those belonging to a VCG can form stable heterokaryons, cells containing two distinct nuclei. Heterokaryons in turn, are formed from hypha! anastomosis, the fusion of two hyphae. Furthermore, subsequent to heterokaryon formation potential mechanisms exist which may generate genetic variability. One is through viral transfer upon hyphal anastomosis. The other mechanism is a form of mitotic recombination referred to as the parasexual cycle. Very little research has been performed to directly obser.ve the cellular events; hypha! anastomosis, heterokaryon formation, and the parasexual cycle in Fusarium oxysporum f. sp. cubense. The purpose of this research was to design and use methods which would allow for the detection of hypha! anastomosis and heterokaryon formation, as well as any characteristics surrounding this event, within and between VCG's in Foe. First, some general growth properties were recorded: the number of nuclei per hypha, the size ofthe hyphal tip cell, the size of the cell adjacent to the hypha! tip (pre-tip) cell, and the number of cells to the first branch point. Second, four methods were designed in order to assay hyphal anastomosis and heterokaryon formation: 1) pairings on membrane: phase or brightfield microscopy, 2) pairings on membrane: fluorescence microscopy, 3) spore crosses: fluorescence microscopy, and 4) double picks in fractionated MMA. All of these methods were promtsmg.

The acculturation of middle income Hispanic households

Research on the consumer behavior of the Hispanic population has recently attracted the attention of marketing practitioners as well as researchers. This study's purpose was to develop a model and scales to examine the acculturation process of Hispanic consumers with income levels of $35,000 and above, and its effects on their consumer behavior. The proposed model defined acculturation as a bilinear and multidimensional change process, measuring consumers' selective change process in four dimensions: language preference, Hispanic identification, American identification, and familism. A national sample of 653 consumers was analyzed. The scales developed for testing the model showed good to high internal consistency and adequate concurrent validity. According to the results, consumers' contact with Hispanic and Anglo acculturation agents generates change or reinforces consumers' language preferences. Language preference fully mediates the effects of the agents on consumers' American identification and familism; however, the effects of the acculturation agents on Hispanic identification are only partially mediated by individuals' language preference change. It was proposed that the acculturation process would have an effect on consumers' brand loyalty, attitudes towards high quality and prestigious brands, purchase frequency, and savings allocation for their children. Given the lack of significant differences between Hispanic and Anglo consumers and among Hispanic generations, only savings allocation for children's future was studied intensively. According to these results, Hispanic consumers' savings for their children is affected by consumers' language preference through their ethnic identification and familism. No moderating effects were found for consumers' gender, age, and country of origin, suggesting that individual differences do not affect consumers' acculturation process. Additionally, the effects of familism were tested among ethnic groups. The results suggest not only that familism discriminates among Hispanic and Anglo consumers, but also is a significant predictor of consumers' brand loyalty, brand quality attitudes, and savings allocation. Three acculturation segments were obtained through cluster analysis: bicultural, high acculturation, and low acculturation groups, supporting the biculturalism proposition.

Anisotropia magnética em nanofilmes com assimetria cristalográfica

This Thesis comprises a theoretical study about the influence of the magnetocrystalline anisotropy on the static and dynamic magnetic properties of nanofilms: monolayers and trilayers coupled through the bilinear and biquadratic exchange fields, for situations in which the systems are grown in unusual [hkl] asymmetric directions. Using a theory based on a realistic phenomenological model for description of nanometric systems, we consider the total free magnetic energy including the Zeeman interaction, cubic and uniaxial anisotropies, demagnetizing and surface anysotropy energies, as well as the exchange terms. Numerical calculations are conducted by minimizing the total magnetic energy from the determination of equilibrium static configurations. We consider experimental parameters found in the literature to illustrate our results for Fe/Cr/Fe trilayer systems. In particular, a total of six different magnetic scenarios are analyzed for three regimens of exchange fields and the [211] and [321] asymmetric growth directions. After numerically minimize the total energy, we use the equilibrium configurations to calculate magnetization and magnetoresistance curves with the respective magnetic phases and corresponding critical fields. These results are also used to establish the boundary for occurrence of saturated states. Within the context of the spin waves, we solve the equation of motion for these systems in order to find the respective associated dispersion relations. The results show similar magnetization and magnetoresistance curves for both [211] and [321] growth scenarios, including an equivalent magnetic transition behavior. However, the combination of those peculiar symmetries and influence of the exchange energies results in attractive properties, including the generation of magnetic states as a function of the asymmetric degree imposed in the [hkl] growth orientations. There is also an increasing incompatibility between the values of saturation fields of magnetization and magnetoresistance for the cases in which a magnetic field acts along intermediate cubic anisotropic axes, particularly in the situations where the bilinear and biquadratic exchange fields are comparable. The dispersion relations and static results are consistent, the corresponding magnetic states are also present in both acoustic and optical modes. Furthermore, Goldstone excitations are also observed for that particular cases of a magnetic field acting in the intermediate axes, an effect related to transitions of second order and to the spontaneous symmetry breaking imposed by the combination of the biquadratic energy with the cubic and uniaxial anisotropies.

Courtship behaviour of western hedgehogs (Erinaceus europaeus) in a rural landscape in Ireland and the first appearance of offspring

A study was conducted to investigate the timing of the breeding season of western hedgehogs (Erinaceus europaeus) in a rural landscape in Ireland, their courtship activity and the first appearance and possible dispersal of juveniles. Between June 2008 and June 2010, 24 hedgehogs (18 ♂ and 6 ♀) were caught and monitored by radio tracking and direct following. A preponderance of males was recorded in both adults and juveniles at the study site and the sex ratio deviated significantly from a 1:1 ratio. Courtship behaviour took place between April and July and occurred almost exclusively in a nine ha pasture. An individual female paired with up to seven males in a season. The first appearance of juveniles was recorded in September (2008) and July (2009). The majority (n=22) of juvenile sightings, both alive and as road kill, occurred in July but they continued to be recorded up until November (n=3). The presence of juveniles at the study site in October 2008 and a pregnant female being found in September 2009 indicated that late litters occur in Ireland.

Effect of road quality in structural health monitoring under operational conditions

The effect of unevenness in a bridge deck for the purpose of Structural Health Monitoring (SHM) under operational conditions is studied in this paper. The moving vehicle is modelled as a single degree of freedom system traversing the damaged beam at a constant speed. The bridge is modelled as an Euler-Bernoulli beam with a breathing crack, simply supported at both ends. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. The unevenness in the bridge deck considered is modelled using road classification according to ISO 8606:1995(E). Numerical simulations are conducted considering the effects of changing road surface classes from class A - very good to class E - very poor. Cumulant based statistical parameters, based on a new algorithm are computed on stochastic responses of the damaged beam due to passages of the load in order to calibrate the damage. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are considered. The findings of this paper are important for establishing the expectations from different types of road roughness on a bridge for damage detection purposes using bridge-vehicle interaction where the bridge does not need to be closed for monitoring.

Effects of vehicle speed in structural health monitoring from operational conditions of bridges

The effects of vehicle speed for Structural Health Monitoring (SHM) of bridges under operational conditions are studied in this paper. The moving vehicle is modelled as a single degree oscillator traversing a damaged beam at a constant speed. The bridge is modelled as simply supported Euler-Bernoulli beam with a breathing crack. The breathing crack is treated as a nonlinear system with bilinear stiffness characteristics related to the opening and closing of crack. The unevenness of the bridge deck is modelled using road classification according to ISO 8606:1995(E). The stochastic description of the unevenness of the road surface is used as an aid to monitor the health of the structure in its operational condition. Numerical simulations are conducted considering the effects of changing vehicle speed with regards to cumulant based statistical damage detection parameters. The detection and calibration of damage at different levels is based on an algorithm dependent on responses of the damaged beam due to passages of the load. Possibilities of damage detection and calibration under benchmarked and non-benchmarked cases are considered. Sensitivity of calibration values is studied. The findings of this paper are important for establishing the expectations from different vehicle speeds on a bridge for damage detection purposes using bridge-vehicle interaction where the bridge does not need to be closed for monitoring. The identification of bunching of these speed ranges provides guidelines for using the methodology developed in the paper.

Topological massive Dirac edge modes and long-range superconducting Hamiltonians

We discover novel topological effects in the one-dimensional Kitaev chain modified by long-range Hamiltonian deformations in the hopping and pairing terms. This class of models display symmetry-protected topological order measured by the Berry/Zak phase of the lower-band eigenvector and the winding number of the Hamiltonians. For exponentially decaying hopping amplitudes, the topological sector can be significantly augmented as the penetration length increases, something experimentally achievable. For power-law decaying superconducting pairings, the massless Majorana modes at the edges get paired together into a massive nonlocal Dirac fermion localized at both edges of the chain: a new topological quasiparticle that we call topological massive Dirac fermion. This topological phase has fractional topological numbers as a consequence of the long-range couplings. Possible applications to current experimental setups and topological quantum computation are also discussed.

Does maternal concern about children's weight affect children's body size perception at the age of 6.5? A community-based study

OBJECTIVE: Though overweight is often established by school entry, not all mothers of such children report weight concerns. Enhancing concern might assist lifestyle change, but could lead to child body dissatisfaction. We investigated (i) perceived/desired body size and body dissatisfaction in mothers and their 6.5-year-old children, and (ii) the impact of earlier maternal concern about overweight on children's body mass index (BMI) status and body dissatisfaction. DESIGN: Prospective community study. SETTING: Melbourne, Australia. SUBJECTS: 317 mother-child dyads. MAIN EXPOSURES: Child and maternal BMI (kg m(-2)) at 4.0 and 6.5 years; maternal concern about child overweight at 4.0 years. OUTCOME MEASURES: Paired perceived and desired body size on 7-point figural rating scales self-reported by mothers and children, and reported by mothers regarding children; dissatisfaction ('desired' minus 'perceived') score. RESULTS: For all three actual BMI perceived size pairings (mother self-report, mother's report on child and child self-report), BMI correlated with perceived body size (r=0.82 (mother self-report); r=0.65 (mother reporting on child); r=0.22 (child self-report); all P<0.001). Similarly, all three dissatisfaction scores were greater with increasing BMI status. Children's own dissatisfaction scores correlated with their actual BMI, but were not related to mothers' own body dissatisfaction scores or with mothers' dissatisfaction with children's body size. Maternal concern about overweight at the age of 4 years was not associated with BMI change, or child body dissatisfaction by the age of 6.5. Most mothers of overweight and obese children (88 and 90%, respectively) regarded their child as the middle figure (that is, 4) or thinner. CONCLUSIONS: Despite low rates of recognition of child overweight, maternal perceptions of the child's body correlated strongly with the child's actual BMI. Maternal concerns about child BMI did not appear to impact on child BMI change or child body dissatisfaction.

Unknown input observer design for one-sided Lipschitz discrete-time systems subject to time-delay

In this paper, we address the problem of unknown input observer design, which simultaneously estimates state and unknown input, of a class of nonlinear discrete-time systems with time-delay. A novel approach to the state estimation problem of nonlinear systems where the nonlinearities satisfy the one-sided Lipschitz and quadratically inner-bounded conditions is proposed. This approach also allows us to reconstruct the unknown inputs of the systems. The nonlinear system is first transformed to a new system which can be decomposed into unknown-input-free and unknown-input-dependent subsystems. The estimation problem is then reduced to designing observer for the unknown-input-free subsystem. Rather than full-order observer design, in this paper, we propose observer design of reduced-order which is more practical and cost effective. By utilizing several mathematical techniques, the time-delay issue as well as the bilinear terms, which often emerge when designing observers for nonlinear discrete-time systems, are handled and less conservative observer synthesis conditions are derived in the linear matrix inequalities form. Two numerical examples are given to show the efficiency and high performance of our results.