Chemically induced residual stresses in dental composites

In several European countries, dental composites are replacing mercury-containing amalgams as the most common restorative materials. One problem with dental composites is residual stresses which may lead to poor performance of the restoration. In the present study, a combined modeling and materials characterization approach is presented and predictions compare well with experimental data on residual stresses. The model takes stress relaxation into account through the complete relaxation time spectrum of the resin. The approach allows for detailed parametric studies where resin and composite composition as well as cure conditions may be tailored with respect to residual stress generation.     

Deformation and fracture of glass bead/ CTBN-rubber/epoxy composites

Carboxyl-terminated butadiene-acrylonitrile-rubber decreases modulus and yield stress of the studied epoxy but increases fracture toughness. The addition of glass bead compensates for the loss in modulus but has little effect on yield stress. However, it significantly contributes to the fracture toughness by providing additional mechanisms for toughening of both the unmodified and rubber-modified epoxy. For the toughened epoxies studied, fracture surfaces gave only limited information on fracture mechanisms since significant energy absorption also occurs in the material below the fracture surface. Suggestions for suitable material compositions for fiber composite matrices are given.     

Paper remote: an augmented television guide and remote control

The television (TV) is one of the most common entertainment devices in homes. Searching and finding TV programs is a common task and using TV guides is one way of performing this. This paper presents three studies that are focused on examining audiences’ TV habits and TV guide usage, evaluating a new concept based on linking paper and pen with TV technology, and studying the audiences’ attitudes toward and anticipated interest in the future guide. The results of our first study emphasize the value of using paper based TV guides and also identify the deficiencies. We also found indications that the advantages and disadvantages of paper-based TV guides are related to the physical properties of paper. Thus, we suggest a solution that uses digital pen and paper technology to offer a new interaction method for TV. A research system “Paper Remote”, is developed and used in the two subsequent studies. Viewers tick designated areas on the paper-based guide to perform actions such as channel switching. However, this solution is not a substitute for the remote control device. We argue that these user studies on linking digital paper to the TV for everyday information navigation illuminate the possibilities of providing innovative solutions also for home information systems also.     

Cryogenic temperature measurement for large applications

We have developed a resistance thermometry system for the acquisition, control and monitoring of temperature in large-scale cryogenic applications. The resistance of the sensor is converted to a voltage using a self-balancing AC bridge circuit featuring square-wave excitation currents down to 1 nA. The system is easily scalable and includes intelligent features to treat special situations such as magnet quenches different from normal operation.     

Food intake after gastrectomy for gastric carcinoma: the role of a gastric reservoir

Patients with carcinoma of the stomach who underwent curative resection were randomized to total gastrectomy (n = 49), total gastrectomy and an S-shaped gastric substitute (n = 28) or subtotal gastrectomy (n = 12); all had a Roux-en-Y reconstruction. The gastric substitute and gastric remnant allowed a volume of 400-500 ml to be installed without increments in basal pressures. The corresponding volume in the Roux limb was 100 ml. Energy intake was approximately 120 kJ/kg preoperative weight per day 3 months after operation, and then remained constant. Patients who had subtotal gastrectomy ate less (91.7 kJ/kg preoperative weight) 3 months after operation, but thereafter increased their intake. Patients allocated to have a gastric pouch or subtotal gastrectomy complained more frequently of adverse postprandial symptoms (P < 0.03) as a major cause of reduced calorie intake. The construction of a gastric reservoir did not improve nutritional adaptation after surgery for gastric carcinoma.     

Dynamics of lung collapse and recruitment during prolonged breathing in porcine lung injury

Oleic acid (OA) injection, lung lavage, and endotoxin infusion are three commonly used methods to induce experimental lung injury. The dynamics of lung collapse and recruitment in these models have not been studied, although knowledge of this is desirable to establish ventilatory techniques that keep the lungs open. We measured lung density by computed tomography during breath-holding procedures. Lung injury was induced with OA, lung lavage, or endotoxin in groups of six mechanically ventilated pigs. After a stabilization period, repetitive computed tomography scans of the same slice were obtained during prolonged expirations with and without positive end-expiratory pressure and during prolonged inspirations after 5 and 30 s of expiration. Lung collapse and recruitment occurred mainly within the first 4 s of breath-holding procedures in all three lung injury models, and some collapse and recruitment occurred even within 0.6 s. OA-injured lungs were significantly more unstable than lungs injured by bronchoalveolar lavage or endotoxin infusion. In this experimental setting, expiration times <0.6 s are required to avoid cyclic alveolar collapse during mechanical ventilation without extrinsic positive end-expiratory pressure.     

Some sexological characteristics of stress incontinent women

The goal of stress incontinence surgery is to prevent opening of the urethra during increases in intra-abdominal pressure. Greater refinements in the understanding of the pathophysiology of incontinence and experience with newer treatments have extended surgical thinking beyond the familiar paradigm "to place the urethra in a high retropubic position." When incontinence is associated with vaginal hypermobility, vaginal support may be sufficient to restore continence if the suburethral vaginal wall is sufficiently strong, an evaluation which must often be made by physical examination alone. However, when the vaginal wall is weak, the urethra will require an alternative form of support, usually a sling. If the urethra is intrinsically deficient, vaginal support may not be sufficient to prevent opening during increased intra-abdominal pressure, and coaptation by sling obstruction or periurethral bulking injection may be required. Most laparoscopic approaches to stress incontinence use Burch's method, which offers excellent urethral stability provided the suburethral vaginal wall is strong. Newer insights into the relation between vaginal mobility and urethral closure are discussed, as well as anatomic aspects of the Burch suspension relevant to laparoscopic repair.     

Improved PLSOM algorithm

The original Parameter-Less Self-Organising Map (PLSOM) algorithm was introduced as a solution to the problems the Self-Organising Map (SOM) encounters when dealing with certain types of mapping tasks. Unfortunately the PLSOM suffers from over-sensitivity to outliers and over-reliance on the initial weight distribution. The PLSOM2 algorithm is introduced to address these problems with the PLSOM. PLSOM2 is able to cope well with outliers without exhibiting the problems associated with the standard PLSOM algorithm. The PLSOM2 requires very little computational overhead compared to the standard PLSOM, thanks to an efficient method of approximating the diameter of the inputs, and does not rely on a priori knowledge of the training input space. This paper provides a discussion of the reasoning behind the PLSOM2 and experimental results showing its effectiveness for mapping tasks.     

Planning Smooth and Obstacle-Avoiding B-Spline Paths for Autonomous Mining Vehicles

We study the problem of automatic generation of smooth and obstacle-avoiding planar paths for efficient guidance of autonomous mining vehicles. Fast traversal of a path is of special interest. We consider fourwheel four-gear articulated vehicles and assume that we have an a priori knowledge of the mine wall environment in the form of polygonal chains. Computing quartic uniform B-spline curves, minimizing curvature variation, staying at least at a proposed safety margin distance from the mine walls, we plan high speed paths. We present a study where our implementations are successfully applied on eight path-planning cases arising from real-world mining data provided by the Swedish mining company Luossavaara-Kiirunavaara AB (LKAB). The results from the study indicate that our proposed methods for computing obstacle-avoiding minimum curvature variation B-splines yield paths that are substantially better than the ones used by LKAB today. Our simulations show that, with an average 32.13%, the new paths are faster to travel along than the paths currently in use. Preliminary results from the production at LKAB show an overall 5%-10% decrease in the total time for an entire mining cycle. Such a cycle includes both traveling, ore loading, and unloading.     

Discourses on age: confronting disputed concepts by means of dialogue

The article explores approaches to discourses concerning age, with different agendas and national contexts. The Dialogue Seminar Method is introduced, as a means of facilitating reflection and access to tacit knowledge. Democratic dialogue requires orchestration, and enables horizontal communication and collective reflection.

---