Evaluation strategies of American and Thai consumers

ABSTRACT The effects of two factors (congruity of product information with consumer expectations and perceived risk associated with the product) on strategies used by consumers to evaluate products are tested in the United States and Thailand. When product information does not match expectations, consumers in both cultures increase evaluation effort and shift from using summary representations stored in memory to evaluation based on actual product attributes. Perceived risk also enhances evaluation effort in both cultures, but does not result in a similar shift from category-based to attributebased processing

Theoretical Evaluation of the Detectability of Random Lesions in Bayesian Emission Reconstruction

Detecting cancerous lesion is an important task in positron emission tomography (PET). Bayesian methods based on the maximum a posteriori principle (also called penalized maximum likelihood methods) have been developed to deal with the low signal to noise ratio in the emission data. Similar to the filter cut-off frequency in the filtered backprojection method, the prior parameters in Bayesian reconstruction control the resolution and noise trade-off and hence affect detectability of lesions in reconstructed images. Bayesian reconstructions are difficult to analyze because the resolution and noise properties are nonlinear and object-dependent. Most research has been based on Monte Carlo simulations, which are very time consuming. Building on the recent progress on the theoretical analysis of image properties of statistical reconstructions and the development of numerical observers, here we develop a theoretical approach for fast computation of lesion detectability in Bayesian reconstruction. The results can be used to choose the optimum hyperparameter for the maximum lesion detectability. New in this work is the use of theoretical expressions that explicitly model the statistical variation of the lesion and background without assuming that the object variation is (locally) stationary. The theoretical results are validated using Monte Carlo simulations. The comparisons show good agreement between the theoretical predications and the Monte Carlo results

LaBr₃:Ce and silicon photomultipliers: Towards the optimal scintillating photon-counting detector

We investigate fast silicon photomultiplier (SiPM)-based scintillation detectors for X-ray photon-counting applications, e.g., photon-counting computed tomography (CT). Such detectors may be an alternative to CdTe/CdZnTe (CZT) and Si detectors, which face challenges related to availability and cost-effective growth of detector-grade material, and detection efficiency, respectively. Here, we experimentally study energy response and count rate performance of a 1 mm × 1 mm single-pixel detector consisting of the readily available LaBr3:Ce scintillator and an ultrafast SiPM. We used three radio-isotopes and an X-ray tube for the experiments. Raw detector signals were processed by a second-order low-pass filter with a cut-off frequency fc equal to 25 MHz or 100 MHz. The detector pulse height was shown to be proportional to photon energy. We measured FWHM energy resolutions of 19.5% (fc=25 MHz) and 21.5% (fc=100 MHz) at 60 keV. The measured X-ray tube spectra showed signs of the expected features of such spectra. The best count rate performance was achieved using fc=100 MHz. In case of paralyzable-like counting and a 30 keV counting threshold, the maximum observed count rate (OCR) was 10.5 Mcps/pixel. For nonparalyzable-like counting and the same threshold, the OCR appeared to approach an asymptotic value greater than 20 Mcps/pixel. These numbers are close to those of CdTe/CZT detectors highly optimized for photon-counting CT. In conclusion, we show promising spectral X-ray photon-counting performance of an LaBr3:Ce scintillation detector with SiPM readout. Depending on the application-specific requirements, miniaturization of the pixel size may be necessary, for which we discuss potential dose-efficient implementations.RST/Medical Physics & Technolog

NIBART: A New Interval Based Algebraic Reconstruction Technique for error quantification of emission tomography images

Abstract. This article presents a new algebraic method for reconstructing emission tomography images. This approach is mostly an interval extension of the conventional SIRT algorithm. One of the main characteristic of our approach is that the reconstructed activity associated with each pixel of the reconstructed image is an interval whose length can be considered as an estimate of the impact of the random variation of the measured activity on the reconstructed image. This work aims at investigating a new methodological concept for a reliable and robust quantification of reconstructed activities in scintigraphic images.

Exploring the role of acculturation in brand choice: a new perspective for targeting Indians living in the UK

Indians are the largest UK ethnic minority, contributing significantly to the UK economy. Although this group's considerable spending power makes them of interest to marketing practitioners, greater insight into their consumer behaviour is required. An understanding of the influence of cultural factors on preferences and behaviour is a priority. This qualitative article considers how consumer acculturation affects the brand preferences of British Indian consumers. Berry's acculturation taxonomy and Mendoza's Cultural Life Style Inventory underpin the organisation of the data collection. The findings reveal distinctive brand choice patterns for individuals from different acculturation categories. Separated individuals use more of the ethnic brands than host brands; most integrated individuals are familiar with both ethnic and host brands; whereas assimilated individuals have a much narrower brand understanding, being familiar mainly with the host brands. The implications for researchers and practitioners are explored