Portfolios of quantum algorithms.

Quantum computation holds promise for the solution of many intractable problems. However, since many quantum algorithms are stochastic in nature they can find the solution of hard problems only probabilistically. Thus the efficiency of the algorithms has to be characterized by both the expected time to completion and the associated variance. In order to minimize both the running time and its uncertainty, we show that portfolios of quantum algorithms analogous to those of finance can outperform single algorithms when applied to the NP-complete problems such as 3-satisfiability.

Intellectual property. Europe's database experiment.

Database protection laws in Europe may have produced a modest, one-time growth spurt for commercial providers. Unfortunately, Europe's new database laws have also produced significant problems including overprotection of low-value data (e.g., telephone books), new barriers to database integration, and further erosion of the public domain. The authors of this Policy Forum caution that these problems could cripple commercial and academic science.

Coping with change: intellectual property rights, new legislation, and the human mutation database initiative.

In 1996, the European Union issued a directive requiring member states to protect databases against unauthorized copying. Similar legislation is currently being considered and will probably be enacted in the US. Such database legislation 1) will almost certainly increase existing pressures on human mutation databases to commercialize, and 2) could inadvertently make human mutation data harder to acquire and use. Strategies for minimizing these difficulties are discussed. Alternatively, a nonprofit, community-wide "depository" could probably support itself by selling sophisticated bioinformatic products to the private sector. The proposed depository would offer substantially similar databases to academic and government users at little or no cost.

Recall intervals: effect on treatment needs: a retrospective study.

The purpose of this retrospective study was to examine the effect of recall intervals on the incidence of dental caries. Data were collected from patient records of a private pediatric dental practice. Variables examined were time of the recall interval, age, race and sex of the patient, and whether the patient lived in a fluoridated area. There were 207 patients who qualified for the study. Of the 207 patients in the study, 173 did not have any teeth with dental caries at the recall visit. A significant difference between increased caries activity and recall interval was not found in this study. There was no significant difference found between the explanatory variables and caries activity.

Recall intervals: effect on treatment needs of the handicapped patient: a retrospective study.

The purpose of the retrospective study was to examine the effect of recall intervals on incidence of dental caries in handicapped patients. Data was collected from patient records of a private pediatric dental practice. Variables examined were time of the recall interval, age, race and sex of the patient, handicap, and whether the patient lived in a fluoridated area or not. Approximately six hundred charts were reviewed which resulted in 83 patients that qualified for the study. Of the 83 patients in the study, 57 did not have dental caries at the recall visit. The relationship between increased caries activity and recall interval was not significant. However, a trend indicating an increased chance of developing caries after a twelve month recall interval was detected.

Inhibitors and activators of fibrinolysis during and after childbirth in maternal and cord blood.

During normal childbirth profound changes in the fibrinolytic system take place. Tissue plasminogen activator (t-PA), the antigen and its biological activity and, the activity of plasminogen activator inhibitor (PAI): were measured in twenty-two healthy women during and shortly after spontaneous delivery (2nd stage and 3rd stage of labour, 48 and 72 hours post partum). Significant increases of plasma t-PA antigen and activity occurred during childbirth and before delivery of the placenta, while the inhibitor remained unchanged. After delivery the PA inhibitor and t-PA antigen showed a steep decline. The activity of t-PA remained largely unchanged during labour and after delivery. The comparison between the activity levels of PAI in infant cord blood and in maternal peripheral blood, taken simultaneously during the process of placental separation, showed significantly higher PAI activity in the mother. In contrast the levels of t-PA activity were found to be significantly higher in cord blood. Our results demonstrate that during the process of child-birth and separation of the placenta distinct alterations in the fibrinolytic system occur most likely due to placental effects.