Making business sense of electronic commerce

Although its infrastructure is still very young, e-commerce continues to create new business models and innovative marketing and technology strategies. To avoid unraveling their core processes, organizations considering e-commerce applications must take time out to evaluate the many facets of adoption and integration. Arguments for not investing in e-commerce are rapidly dissolving. It is now widely accepted that a business cannot ignore e-commerce investment without incurring heavy penalties over the long run. We believe organizations that want to invest in e-commerce must have a significantly higher degree of technological fluency and a bolder approach to experimentation with unfamiliar business models than they would for investments in other areas. Successfully exploiting e-commerce requires creatively linking an organization's strategy and its supporting technology as well as managing pervasive IT applications that change very quickly and are becoming increasingly integrated and convergent. Only then can enterprises achieve the flexible and adaptive behavior that is central to effective e-commerce     

Psychiatric and psychologic aspects of stomatologic diseases, or stomatologic aspects of psychiatric diseases. Review of the literature

Dental symptoms, oral medicine and psychiatric and psychologic problems have strict relationships in several domains. Behavior and behavioural problems (deficient oral hygiene, lack of regular dental control, dependence of nicotine or alcohol, etc.) as well as certain psychiatric diseases influence the patients' dental state to a great extent. There are further problems determined by the different types of anxiety, fear and bad previous experiences which have an impact on people's attitudes towards dental treatment and the development of hygienic habits. Dentists' psychologic and psychiatric knowledge can have a considerable contribution to the reduction of the patients' anxiety, furthermore to an appropriate treatment, by the recognition of the underlying psychiatric disease.     

The Role of Phase Changes in TiO<Subscript>2</Subscript>/Pt/TiO<Subscript>2</Subscript> Filaments

This work analyses the role of phase changes in TiO₂/Pt/TiO₂ layer stacks for micro-heater application regarding their stability and reliable operation. The polycrystalline Pt layer wrapped in a TiO₂ adhesion layer underwent a continuous recrystallisation in a self-heating operation causing a drift in the resistance (R) versus temperature (T) performance. Simultaneously, the TiO₂ adhesion layer also deteriorates at high temperature by phase changes from amorphous to anatase and rutile crystallite formation, which not only influences the Pt diffusion in different migration phenomena, but also reduces the cross section of the Pt heater wire. Thorough scanning electron microscopy, energy dispersive spectroscopy, cross-sectional transmission electron microscopy (XTEM) and electron beam diffraction analysis of the structures operated at increasing temperature revealed the elemental structural processes leading to the instabilities and the accelerated degradation, resulting in rapid breakdown of the heater wire. Owing to stability and reliability criteria, the conditions for safe operation of these layer structures could be determined.     

Combining RF encoding with parallel imaging: a simulation study

Object  

The aim of this work was to investigate combining spatial encoding by radio frequency (RF) excitation with conventional parallel imaging (PI) methods to determine whether this could improve overall imaging performance.     

Two methods for semi-automated quantification of changes in ventricular volume and their use in schizophrenia

Two semi-automated methods for quantification of ventricular volume change from baseline and follow-up magnetic resonance imaging scans have been developed. Technique 1 employs direct segmentation of the ventricles from both the scans using thresholding and contour extraction. Technique 2 operates on difference images produced by voxel based intensity subtraction of the baseline from the registered follow-up images. Here, all voxels with intensities above a noise threshold and in a restricted area are monitored to compute volumetric changes. In phantom measurements the first technique was accurate to 0.0046%, the second to 0.167% of the phantom volume. Results from normal volunteers was that the average ventricular volume changed by 1.52% and 1.54% for images acquired within 9 months using techniques 1 and 2, respectively. With schizophrenic patients mean change of 10.78% and 9.43% were found employing the first and second procedures, respectively. All measurements agreed with a radiologist's visual grading of the changes. Robust, objective, fast, easy-to-use, and fairly accurate procedures have been developed and validated to quantify volumetric changes.     

Impact of number of channels on RF shimming at 3T

Object

At high-field strengths (≥3T) inhomogeneity of the radio frequency (RF) field and RF power deposition become increasingly problematic. Parallel Transmission (PTx)—the use of segmented transmission arrays with independently driven elements—affords the ability to combat both of these issues. There are a variety of existing designs for PTx coils, ranging from systems with two channels to systems with eight or more. In this work, we have investigated the impact of the number of independent channels on the achievable results for both homogeneity improvement and power reduction in vivo.

Materials and methods

A 3T Philips Achieva MRI system fitted with an 8-channel PTx body coil was driven so as to emulate configurations with 1, 2 4 and 8 independent channels. RF shimming was used in two different anatomies in order to assess improvements in RF homogeneity.

Results

Significant homogeneity improvements were observed when increasing from 1 to 2, 2 to 4, and 4 to 8 channel configurations. Reductions in RF power requirements and local SAR were predicted for increasing numbers of channels.

Conclusion

Increasing the number of RF transmit channels adds extra degrees of freedom which can be used to benefit homogeneity improvement or power reduction for body imaging at 3T.     

An efficient automated z-shim based method to correct through-slice signal loss in EPI at 3T

Object  To develop an efficient, automated method to correct through-slice signal loss in gradient-echo EPI at 3T. Material and methods  The optimal choice of two z-shim values for signal recovery was determined from simulations and experiments. The specific required z-shim values are determined using a rapid calibration method that combines information about the slice profile with a sparse set of measurements. The proposed correction method was implemented for a language fMRI study which suffers from signal loss near the auditory canals, and tested on 12 volunteers. Results  Using a square root sum of squares combination of two z-shim values full signal restoration (to within 2% of the correct value) was achieved in 96% of all correctable brain pixels for 3 mm slices, and partial correction in pixels outside this range. In all subjects, language processing activation was recovered in the inferior and lateral areas of the left temporal lobe which was not detectable with conventional fMRI. Conclusion  The careful choice of two z-shim values by the proposed method achieves through-slice signal loss correction for the majority of pixels in the brain for 3 mm slices at 3T.     

MRI of moving subjects using multislice snapshot images with volume reconstruction (SVR): application to fetal, neonatal, and adult brain studies

Motion degrades magnetic resonance (MR) images and prevents acquisition of self-consistent and high-quality volume images. A novel methodology, Snapshot magnetic resonance imaging (MRI) with Volume Reconstruction (SVR) has been developed for imaging moving subjects at high resolution and high signal-to-noise ratio (SNR). The method combines registered 2-D slices from sequential dynamic single-shot scans. The SVR approach requires that the anatomy in question is not changing shape or size and is moving at a rate that allows snapshot images to be acquired. After imaging the target volume repeatedly to guarantee sufficient sampling every where, a robust slice-to-volume registration method has been implemented that achieves alignment of each slice within 0.3 mm in the examples tested. Multilevel scattered interpolation has been used to obtain high-fidelity reconstruction with root-mean-square (rms) error that is less than the noise level in the images. The SVR method has been performed successfully for brain studies on subjects that cannot stay still, and in some cases were moving substantially during scanning. For example, awake neonates, deliberately moved adults and, especially, on fetuses, for which no conventional high-resolution 3-D method is currently available. Fine structure of the in-utero fetal brain is clearly revealed for the first time and substantial SNR improvement is realized by having many individually acquired slices contribute to each voxel in the reconstructed image.     

Perisomatic Inhibition and Its Relation to Epilepsy and to Synchrony Generation in the Human Neocortex

Inhibitory neurons innervating the perisomatic region of cortical excitatory principal cells are known to control the emergence of several physiological and pathological synchronous events, including epileptic interictal spikes. In humans, little is known about their role in synchrony generation, although their changes in epilepsy have been thoroughly investigated. This paper demonstraits how parvalbumin (PV)- and type 1 cannabinoid receptor (CB1R)-positive perisomatic interneurons innervate pyramidal cell bodies, and their role in synchronous population events spontaneously emerging in the human epileptic and non-epileptic neocortex, in vitro. Quantitative electron microscopy showed that the overall, PV+ and CB1R+ somatic inhibitory inputs remained unchanged in focal cortical epilepsy. On the contrary, the size of PV-stained synapses increased, and their number decreased in epileptic samples, in synchrony generating regions. Pharmacology demonstrated—in conjunction with the electron microscopy—that although both perisomatic cell types participate, PV+ cells have stronger influence on the generation of population activity in epileptic samples. The somatic inhibitory input of neocortical pyramidal cells remained almost intact in epilepsy, but the larger and consequently more efficient somatic synapses might account for a higher synchrony in this neuron population. This, together with epileptic hyperexcitability, might make a cortical region predisposed to generate or participate in hypersynchronous events.