Investigating customer satisfaction dimensions with service quality of online auctions: an empirical investigation of e-Bay

Over the recent years, C2C (consumer-to-consumer) electronic market has increased rapidly, and has become the most active segment of e-markets today. Despite the growth and popularity of online auctions and especially of e-Bay, which has been considered to be one of the most profitable e-commerce companies, the online auction environment is risky and transactions are complex due to the fact that buyer and seller do not know each other and they are not familiar. Although many studies have examined the impact of e-service quality on customer satisfaction in B2C (business-to-consumer) or B2B (business-to-business) commerce, the literature is insufficient in the case of C2C commerce. However, a number of authors have conducted research in C2C and particularly in e-Bay but in all of the cases, data source from e-Bay’s feedback system was employed in order to investigate service quality issues. Nevertheless, in this study a field research was conducted in order to collect the necessary data and thus reducing possible bias. The purpose of this paper is to examine some determinants of satisfaction with service quality dimensions in the online auction environment. More specifically, this paper is examining the case of e-Bay, in order to have a better understanding of buyers’ satisfaction in this risky environment. The paper’s aim is accomplished through an empirical investigation of a sample of 2,099 buyers of e-Bay, examining buyers’ expectation and perception levels towards service quality of e-Bay. Gap analysis was first employed in order to identify users’ disconfirmation dimensions in the online auction market place. Some research hypotheses are formulated to find out whether these dimensions have a positive disconfirmation. In most of the cases a positive disconfirmation is tracked down. Secondly, factor analysis was utilized to identify broad determinants of e-Bay service quality. The pool of the initial items deduced to four factors. These factors are, to a degree, differentiated in the Greek environment from factors found in other studies. A second round of research hypotheses are formulated again to find out whether those factors are related to the users’ disconfirmation dimensions. Finally, a new theoretical model is proposed based on the above mentioned hypotheses.     

Malignant tumors of the thyroid

Carcinoma of the thyroid gland is not common. The majority of lesions in this series were differentiated in type. The treatment of choice is almost total thyroidectomy supplemented by I131 in some cases. L-thyroxine was prescribed routinely for all patients postoperatively for replacement and depression treatment. The immediate postoperative mortality was about 1% and prognosis is relatively good. Undifferentiated thyroid carcinomas are fast growing and very lethal and unfortunately no method of treatment is effective. Only four patients in this group survived more than a year.     

Modeling and optimization of multi-tubular metal hydride beds for efficient hydrogen storage

This work presents a novel systematic approach for the optimal design of a multi-tubular metal hydride tank, containing up to nine tubular metal hydride reactors, used for hydrogen storage. The tank is designed to store enough amount of hydrogen for 25 km range¹, for a fuel cell vehicle. A detailed 3D Cartesian, mathematical model is developed and validated against a 2D cylindrical developed by Kikkinides et al. [1]. The objective is to find the optimal process design so as to increase the overall thermal efficiency, and thus minimize the storage time. Optimization results indicate that almost 90% improvement of the storage time can be achieved, over the case where the tank is not optimized and for a minimum storage capacity of 99% of the maximum value.     

Off lattice Monte Carlo simulations of AB hybrid dendritic star copolymers

The conformational properties of Hybrid Dendritic Star copolymers (HDS) which combine the characteristics of dendrimers with those of flexible polymers are studied, for the first time, by means of Off Lattice Monte Carlo simulations. Using the efficient Pivot algorithm we calculate the asphericity and the acylindricity of the whole molecule for various solvent conditions and different characteristics of dendritic and star chains. Moreover, the effects of the number and the length of star branches on the conformation of the dendritic part are also studied. By considering the HDS copolymers as ‘hairy spheres’ we have calculated the star monomer distribution profiles. The shapes of the profiles are compared with previous Monte Carlo results.     

Semi-autonomous Navigation of a Robotic Wheelchair

The present work considers the development of a wheelchair for people with special needs, which is capable of navigating semi-autonomously within its workspace. This system is expected to prove useful to people with impaired mobility and limited fine motor control of the upper extremities. Among the implemented behaviors of this robotic system are the avoidance of obstacles, the motion in the middle of the free space and the following of a moving target specified by the user (e.g., a person walking in front of the wheelchair). The wheelchair is equipped with sonars, which are used for distance measurement in preselected critical directions, and with a panoramic camera with a 360 degree field of view, which is used for following a moving target. After suitably processing the color sequence of the panoramic images using the color histogram of the desired target, the orientation of the target with respect to the wheelchair is determined, while its distance is determined by the sonars. The motion control laws developed for the system use the sensory data and take into account the non-holonomic kinematic constraints of the wheelchair, in order to guarantee certain desired features of the closed-loop system, such as stability. Moreover, they are as simplified as possible to minimize implementation requirements. An experimental prototype has been developed at ICS–FORTH, based on a commercially-available wheelchair. The sensors, the computing power and the electronics needed for the implementation of the navigation behaviors and of the user interfaces (touch screen, voice commands) were developed as add-on modules and integrated with the wheelchair.     

Maximization of users experience in websites: estimating the optimum size of the multimedia content

In this paper, an extended experimental research is performed in order to calculate the mean opinions score (MOS) of several users considering quality of experience variables such as “information perception” and “multimedia type of preference”. The experimental campaign resulted in a great archive of measurements of the MOS of users over several multimedia files. It was found that multimedia type affects information perception whereas users prefer information to be presented by certain multimedia types. A quality factor $q_{i}$ is introduced for the first time for each multimedia type at the best of the authors’ knowledge. This quality factor connects MOS (i.e. user quality experience) and file size (i.e. network resources) with multimedia type. These quality factors express a measure of how MOS is affected by each individual multimedia type and it is inherent to the multimedia type. Approximating equations incorporating MOS and file size as well as quality factors are extracted and are used to construct an optimization problem. The optimization problem has as a target to optimize (i.e. maximize) the overall MOS of “information perception” and “multimedia type of preference” of a website that present information using several multimedia types, constrained by the total size of the website in bytes. Finally, an upper bound for the MOS is extracted based on the total file size of the website in terms of bytes.     

Identification of Doppler microembolic signals with a bigate probe in patients with prosthetic heart valves

BACKGROUND AND PURPOSE: The applicability of a bigate probe, simultaneously harvesting two spatially separated vessel segments, in the identification of Doppler microembolic signals (MES) was evaluated. METHODS: One hundred and ninety-seven patients with artificial heart valves were bilaterally monitored over two segments of each middle cerebral artery, with a minimal distance of 5 mm between them, using 2 MHz probes. Time delay in the appearance of high intensity transients between the two segments was calculated off-line, using dedicated software, integrated in the Doppler device. RESULTS: Bigate monitoring was feasible in 96% of patients. MES prevalence and counts were 37% and 26 (18-44) respectively. All but 8.8% of the 2932 MES signals recorded appeared in both Doppler channels, with a time delay of 4.4 (4.2-4.7) msec (range between 0 and 34 msec). Time delay in 97% of artifact signals was under 1 msec. Application of 1 msec as low and 20 msec as high cut-off point between MES and artifacts resulted in the correct identification of 97% of artifacts and 89.6% of MES. CONCLUSIONS: The multigate approach is a reliable method for identification of Doppler microembolic signals in patients with prosthetic heart valves. The value of this technique in other patient groups remains to be evaluated.     

Hemoglobin-mediated lipid oxidation of protein isolates obtained from cod and haddock white muscle as affected by citric acid,calcium chloride and pH

Acid or alkali solubilization followed by isoelectric precipitation can be used to isolate proteins with good functional properties from muscle tissue. Both acid (pH 3.0) and alkali (pH 10.5) treatment of the muscle decreased lipid oxidation catalyzed by hemoglobin. Citric acid and calcium chloride improved the oxidative stability of both acid- and alkali-solubilized muscle protein isolates when added to the homogenized muscle before separating the membrane or directly to the isolated membranes in the assay. Citric acid may have functioned in part by lowering the pH and destroying preformed peroxides. Exposing the muscle and the hemoglobin together at pH 3 promoted lipid oxidation, while addition of citric acid/calcium chloride or press juice to washed cod prior to solubilization inhibited lipid oxidation even when the tissue and hemoglobin were acidified together.     

Remote monitoring of electromagnetic signals and seismic events using smart mobile devices

This study presents the design and development of a novel mobile wireless system to be used for monitoring seismic events and related electromagnetic signals, employing smart mobile devices like personal digital assistants (PDAs) and wireless communication technologies such as wireless local area networks (WLANs), general packet radio service (GPRS) and universal mobile telecommunications system (UMTS). The proposed system enables scientists to access critical data while being geographically independent of the sites of data sources, rendering it as a useful tool for preliminary scientific analysis.     

Interleukin 1 (IL-1) causes changes in lateral and rotational mobilities of IL-1 type I receptors

To investigate IL-1-dependent interactions of IL-1 type I (IL-1 RI) receptors on intact cells, lateral and rotational mobilities and detergent insolubility were investigated. Lateral mobility was measured by fluorescence photobleaching recovery, using a Cy3-modified, noncompetitive mAb specific for IL-1RI (M5) bound to wild-type IL-1 RI or mutant IL-1 RI with a truncated cytoplasmic tail. Addition of IL-1 causes significant reduction in the mobile fraction of wild-type IL-1 RI for two different transfected cell lines. For the mutant IL-1 RI, no significant decrease in response to IL-1 is observed, indicating that the missing cytoplasmic segment is involved in IL-1-dependent interactions of IL-1 RI that lead to reduced lateral mobility on the cell surface. The rotational mobility of IL-1 RI was assessed with phosphorescence anisotropy decay measurements using erythrosin-labeled M5. IL-1 decreases the rotational mobility of cell surface IL-1 RI on the microsecond time scale and also increases the initial anisotropy, indicating loss in segmental motion. Measurements of resistance to solubilization by Triton X-100 showed that IL-1 binding increases the fraction of IL-1 RI sedimenting with cytoskeletal residues. The IL-1 receptor antagonist protein (IL-1ra) causes partial effects in reducing rotational mobility and increasing detergent insolubility of M5-lableled IL-1 RI, indicating that this ligand causes structural changes in the presence of the dimerizing M5 mAb. These ligand-dependent physical interactions of IL-1 RI on the cell surface may be related to signal initiation by this receptor.