Return Dates Research Articles

User Acceptability Patterns for Mefloquine and Doxycycline Malaria Chemoprophylaxis.

Background: The objective of this study was to profile the user acceptability (self-reported adverse effects and compliance patterns) for mefloquine (250 mg weekly) and doxycycline (100 mg daily), which are currently the recommended malaria chemoprophylactic regimens for chloroquine resistant areas. Methods: Travelers with return dates between November 1993 and October 1994 were enrolled in the study at a pretravel consultation at the Traveller's Medical and Vaccination Centres (TMVC) clinics in Adelaide and Melbourne, if they had been prescribed either mefloquine or doxycycline as the sole chemoprophylactic for their trip. The choice of antimalarial was decided after intensive discussions of the two regimens, contraindications, potential side effects, relative costs, and preferred efficacy. Questionnaires relating to self-reported morbidity and compliance levels were mailed to travelers approximately 2 weeks after their return to Australia. Results: Two hundred and eighty-five travelers (60.0% female, 40.0% male) used mefloquine for a mean of 6.5 tablets. Overall, 51.2% of users experienced illness or symptoms while taking the medication. Symptoms attributed by travelers to mefloquine, and usually temporally related to it, were reported by 37.9% of all users. Adverse events with significant impact on activities were reported by 14.6% of all female users and 6.1% of all male users. On return, 78.2% reported complete compliance with the mefloquine regimen overall; 6.3% stopped the drug specifically because of adverse effects, which were attributed to the drug and which were interfering with daily activities (8.8% females and 2.6% males). Three hundred and eighty-three travelers (47.8% female and 52.2% male) used doxycycline for a mean of 27.5 daily doses. Health problems were experienced by 36.8% of travelers and 21.4% overall experienced what they considered to be adverse drug effects. Troublesome effects were reported by 8.7% of all females and 4.5% males. Complete compliance with the regimen was reported by 68.1% of users. Overall, 5.7% stopped early because of adverse effects, which were attributed to the drug and which were interfering with daily activities (6.6% females, 5.0% males). Conclusions: Drug morbidity must be a consideration when prescribing antimalarial drugs. Noted in this study was the finding of a greater number of adverse events reported by females, particularly for mefloquine. The reasons for this difference between males and females will need to be further explored.

Phenotypic Variation in the Arrival Time of Breeding Salamanders: Individual Repeatability and Environmental Influences

We address the question of whether individual variation in arrival date of breeding salamanders at a temporary pond is repeatable among years. We present data on variation in the date of arrival of individually marked males and females, and date of pond-filling over 12 years at a breeding site. These data allow us to partition variances within and among individuals, but remove the effects of annual environmental differences by standardizing annual return dates. Date of arrival differed significantly among individual males and females. Repeatability for date of return of individual males was (r = 0.0665), but significantly higher for females (r = 0.1662). Snout-vent length had no effect on the date of return for females, but small males returned earlier than large males

Meteoric storms and formation of meteor streams

AbstractMeteoric storms must be very young formations, since planetary perturbations disperse any dense cloud of meteoroids within several revolutions around the sun. It is shown that, by comparing the dates of appearances of the storms of a meteor stream with the return dates of the parent comet, insight can be gained into the problem of the origin and early evolution of such a stream. Applying a recent theory of particle ejection from comets, we have developed a formula relating the character of motion of a cloud of meteoroids to the circumstances of ejection.Practical application of the method to the Leonid, Perseid and η-Aquarid storms indicates low mass density of cometary meteoroids (not more than 0.3 g/cm3), ejection velocities of tens to hundreds of meters per second (with water vapor as the drag force), and suggests that meteoroids are ejected from periodic comets predominantly after perihelion. This finding contrasts with observational evidence of the type II tails of ‘new’ dust-rich comets. It is concluded that the discrepancy may actually reflect structural differences between the ‘new’ and periodic comets.