This paper reviews the relevant dental literature concerning the effect of die-spacing on crown elevation and pre-and post-cementation crown retention. Techniques of providing die-spacing and measurement of the thickness of die-spacer are discussed. A review of the role of the provision of a cement space in reducing post-cementation crown elevation is presented. Factors which may affect crown retention prior to and following cementation are also reviewed. The influence of variables in techniques and experimental design on the results of the studies reviewed is discussed.Key words: Die-spacing, crown elevation, pre-cementation retention, post-cementation retention.(Received for publication January 1996. Revised March 1996 Accepted April 1996.) IntroductionFull crowns frequently do not seat with minimal m a r ginal discrepancy following cementat i o n .

Exercise induces a selective redistribution of CD62L(-) T lymphocytes. This study examined the effects of beta adrenergic receptor blockade on this phenomenon. Twelve healthy men were exercised to exhaustion on a treadmill prior to and following 1 week of treatment with the nonselective beta antagonist propranolol or the beta1 selective antagonist metoprolol. Dynamic exercise resulted in a significant lymphocytosis (p < 0.001). CD8(+)CD62L(-) T cells showed a greater than 3-fold increase in response to exercise (p < 0.001) as compared to CD8(+)CD62L(+) T cells, which showed a more modest increase. Treatment with the nonselective beta antagonist propranolol significantly attenuated the preferential increase of circulating CD8(+)CD62L(-) lymphocytes (p = 0.01) but had no effect on CD8(+)CD62L(+) T cells. Treatment with the beta1 selective antagonist metoprolol did not affect the response of either subset. Our findings replicate a prior study indicating that CD62L expression influences T lymphocyte trafficking in response to exercise and extends those findings by showing that this phenomenon is mediated, in part, via the beta2-adrenergic receptor.

Studies suggest that physical fitness promotes cardiovascular health, including improved endothelial function and possibly reduced inflammatory responses to stressors. This study examined the effects of fitness on leukocyte-endothelial adhesion in response to an acute exercise challenge. Peripheral blood mononuclear cell (PBMC) adhesion to human umbilical venous endothelial cells (HUVEC) was examined in 18 more-fit and 19 less-fit individuals [mean age 39 yr (SD 11)] before and after a 20-min treadmill exercise at 65-70% peak oxygen consumption. PBMC were isolated from whole blood (Ficoll-Paque) at rest and immediately after exercise. HUVEC were incubated for 4 h in the presence of cytokines IL-1 and IL-8 to activate endothelial adhesion molecule expression. Fit subjects showed a significant reduction in PBMC-HUVEC adhesion after exercise (P < 0.01) compared with less-fit subjects, who showed no significant change. Regardless of fitness levels, both at rest and in response to exercise, soluble ICAM-1 in the incubation media attenuated PBMC-HUVEC adhesion by approximately 81% (P < 0.001). The findings indicate that immune cells that demarginate in response to exercise have reduced ability to adhere in individuals who are physically fit, an effect apparently independent of ICAM-1 binding. The findings provide evidence of how physical fitness might protect individuals from inflammatory responses to exercise.

Background: Chronic heart failure (CHF) patients with elevated depression symptoms are at greater risk of morbidity and mortality. The mechanisms linking symptoms of depression with disease progression in CHF are unclear. However, research studies have found evidence of alterations in immune activity associated with depression symptoms that may influence heart function. The present study sought to determine the relationship between depression symptoms and chemotaxis of peripheral blood mononuclear cells (PBMCs) in CHF patients, both at rest and in response to moderate exercise. Methods and Results: Sixty-five patients diagnosed with CHF (mean age, 59.8 6 14.5 years) and 45 non-CHF control subjects (mean age, 52.1 6 11.6) completed the Beck Depression Inventory (BDI) before undergoing a moderate 20-minute bicycle exercise task. Chemotaxis of PBMCs was examined in vitro to a bacterial peptide f-met leu phe (fMLP) and a physiologic chemokine, stromal cell derived factor-1 (SDF-1) immediately before and after exercise. CHF patients had reduced chemotaxis to SDF-1 (P 5 .025) compared with non-CHF subjects. Higher BDI scores were associated with reduced baseline chemotaxis to SDF-1 in both CHF and non-CHF subjects (P 5 .027). In contrast, higher BDI scores were associated with increased chemotaxis to fMLP (P 5 .049) and SDF-1 (P 5 .018) in response to exercise in the CHF patients. Conclusion: The present study suggests a shift in immune cell mobility in CHF patients with greater depression symptom severity, with reduced chemotaxis to a physiologically specific chemokine at rest but increased chemotaxis to both nonspecific and specific chemical attractants in response to physical activity. This could have implications for cardiac repair and remodeling in CHF patients and therefore may affect disease progression.

The worldwide offshore rig chartering business is a significant business with $7 billion to $10 billion in annual expenditures. A study of bidding and contracting practices reveals major inefficiencies in the processes involved in this business, and in the variability of economic decisions, as evidenced by fixture ranges of up to ± $55,000/day for rigs of similar capabilities. The market lacks transparency. Rig chartering supply and demand have very different characteristics. While supply is essentially inelastic, demand is highly volatile. This creates complementary needs for operators and contractors. Operators need:Knowledge of rig capabilities including recent contracts and activities.Knowledge of rig availability and future commitments.The ability to quickly develop multiple contingency drilling scenarios.Easy collaboration with partners and colleagues. Contractors need:Knowledge of upcoming drilling projects and rig capability requirements.Knowledge of competitors' rig dispositions and capabilities.Ability to manage their fleets. Both need:Detailed current supply and demand and dayrate information in each market segment to facilitate tactical and strategic decision-making.Standardized contracting processes. Several companies are managing their rig contracting businesses online, using a real-time expert system to give them the insight they need. Having the right rig for the right job creates tremendous economic advantages. Operators are able to use their drilling budgets more efficiently. Contractors are better able to match their fleets' capabilities with market conditions. This paper offers several examples of decisions that have benefited greatly from market transparency. For example, market insights were essential in helping to determine whether to invest in a rig upgrade or newbuild, as well as how much to invest. Similarly, the ability to lease rigs competitively on the spot market depends on access to market and competitive information. This paper provides examples of efficiency improvements by both operators and contractors, as well as the methodology and results of price/risk analyses. Introduction The demands on business are increasing year on year; the Oil Business is not immune. Every year businesses are challenged to "do more, with less"; execute more projects with less people, develop new products faster with less investment and evaluate more options in less time. To succeed, companies must continually improve their efficiencies. Efficiency gains have traditionally been found in two key areas: improving the timeliness and quality of business decisions and removing the friction or waste in the business processes. This paper will address the opportunities to improve efficiency in the rig contracting business that result from embracing and adopting digital technologies that deliver information to support decisions, that improve inter- and intra-company collaboration and that streamline rig contracting processes. It's All About Decisions and Processes No doubt, business is all about making decisions. Whether the decision involves building a new corporate headquarters or buying a new copy machine, people have to gather the requisite information, analyze it, consider alternatives and select options, and finally, decide. The oil business is no different, except for the dollar magnitude of the decisions, the high uncertainty of those decisions, and the limited time frame in which to make them.