Tissue necrosis under a Nance palatal arch: a case report.

A Nance palatal arch is a method of reinforcing anchorage to help prevent mesial movement of maxillary first permanent molars. It is recognised that it is difficult to maintain oral hygiene around the appliance and that iatrogenic damage can occur. We present a case of a 22-year-old male patient in whom the palatal mucosa became necrotic, palatal bone became exposed and long-term periodontal damage occurred. We describe the case, his treatment and the resolution of the inflammation as well as exploring the causes for the damage and alternate treatment options.

Additive manufacturing of polymer-derived ceramics.

The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

Six opinions on IT security. Panel discussion.

Physicians consult over the Internet. Diagnoses are delivered via E-mail. Data is kept in multimedia repositories. Health care IT is filled with data security challenges. Here's what six experts think about the possibilities and vulnerabilities.

Reproducibility of left ventricular myocardial volume and mass measurements by ultrafast computed tomography.

Ultrafast computed tomography has been reported to be an accurate method of measuring left ventricular mass in dogs. To assess the interstudy, intraobserver and interobserver variability of left ventricular myocardial mass measurements in humans, left ventricular myocardial volume was measured three times within 24 h in 16 patients with ischemic heart disease. The mean percent difference of the mean of the three studies performed was -0.01 +/- 1.4% (range -2.9% to 3.6%). The regression analysis for the intraobserver variability at baseline was: Y = -4.33 + 1.03X; r = 0.99, SEE = 3.5 ml. The mean percent difference of the mean of the two sets of measurements performed by two independent observers was 0.28 +/- 2.1% (range -4.35% to 4.35%). The interobserver variability excluding papillary muscles at baseline study was: Y = -4.34 + 1.06X; r = 0.99, SEE = 1.5 ml. The regression analysis with versus without papillary muscles showed: Y = -8.72 + 0.97X; r = 0.96, SEE = 2.6 ml. Regression analysis to assess the variability of 24-h studies at end-systole versus end-diastole revealed: Y = 3.07 + 0.94X; r = 0.97, SEE = 1.8 ml. In conclusion, ultrafast computed tomography is a minimally invasive technique, with very low interstudy, intraobserver and interobserver variability for left ventricular myocardial volume and mass determinations in serial studies.

Effects of venesection on cerebral function in chronic lung disease.

Regional cerebral blood flow measurements and neuropsychological testing were conducted before and after venesection on 6 patients with polycythemia secondary to chronic obstructive pulmonary disease. Venesection resulted in lowered viscosity and hematocrit, and an accompanying improvement in cerebral perfusion and mental function. Blood flow was significantly increased in the left cerebral hemisphere following phlebotomy, and there was significant improvement in sensory/mental function. Cerebral function would appear to be related to blood flow alterations influenced by the viscosity of the blood.