Behavioral responses of the parsnip webworm to host plant volatiles

Sixth instars of the parsnip webworm, Depressaria pastinacella, orient by olfaction to bud, male flowers, and female flowers of their primary host plant, Pastinaca sativa. Because octyl acetate and octyl butyrate are characteristic of tissues consumed by the sixth instar, we investigated the influence of these esters on webworm feeding behavior and chemo-orientation. Although octyl acetate and octyl butyrate are feeding deterrents, and octyl butyrate is an olfactory repellent, octyl acetate serves as an olfactory attractant. In olfactometers, webworms do not show a preference when given a choice between octyl acetate and host plant tissues. These findings suggest that octyl acetate is a sufficient cue for olfactory orientation. Such behavior may explain differences in the relative abundance of these esters observed among populations of wild parsnip under differential selection pressure from these insects.     

Dynamics and fragmentation of thick-shelled microbubbles

Localized delivery could decrease the systemic side effects of toxic chemotherapy drugs. The unique delivery agents we examine consist of microbubbles with an outer lipid coating, an oil layer, and a perfluorobutane gas core. These structures are 0.5-12 /spl mu/m in radius at rest. Oil layers of these acoustically active lipospheres (AALs) range from 0.3-1.5 /spl mu/m in thickness and thus the agents can carry a large payload compared to nano-scale drug delivery systems. We show that triacetin-based drug-delivery vehicles can be fragmented using ultrasound. Compared with a lipid-shelled contrast agent, the expansion of the drug-delivery vehicle within the first cycle is similar, and a subharmonic component is demonstrated at an equivalent radius, frequency, and driving pressure. For the experimental conditions explored here, the pulse length required for destruction of the drug-delivery vehicle is significantly greater, with at least five cycles required, compared with one cycle for the contrast agent. For the drug-delivery vehicle, the observed destruction mechanism varies with the initial radius, with microbubbles smaller than resonance size undergoing a symmetric collapse and producing a set of small, equal-sized fragments. Between resonance size and twice resonance size, surface waves become visible, and the oscillations become asymmetrical. For agents larger than twice the resonance radius, the destruction mechanism changes to a pinch-off, with one fragment containing a large fraction of the original volume.     

Nondestructive subharmonic imaging

Ultrasound contrast agent microbubbles are intravascular agents that can be used to estimate blood perfusion. Blood perfusion may be estimated by destroying the bubbles in a vascular bed and observing the refresh of contrast agents back into the vascular bed. Contrast agents can be readily destroyed by traditional imaging techniques. The design of a nondestructive imaging technique is necessary for the accurate quantification of contrast agent refresh. In this work, subharmonic imaging is investigated as a method for nondestructive imaging with the contrast agent microbubble MP1950 (Mallinckrodt, Inc., St. Louis, MO). Optical observation during insonation, in conjunction with a modified Rayleigh-Plesset (R-P) analysis, provides insight into the mechanisms of and parameters required for subharmonic frequency generation. Subharmonic imaging with a transmission frequency that is the same as the resonant frequency of the bubble is shown to require a minimum pressure of insonation that is greater than the experimentally-observed bubble destruction threshold. Subharmonic imaging with a transmission frequency that is twice the resonant frequency of the bubble produces a subharmonic frequency response while minimizing bubble instability. Optimization is performed using optical experimental analysis and R-P analysis     

The design of next generation in-vehicle navigation systems for the older driver

It has been proposed that the current design of in-vehicle displays may not be appropriate for the older driver. This paper describes an empirical, road-based investigation of the benefits to older and younger drivers of providing landmarks within the instructions presented by an in-vehicle navigation system. Thirty two participants navigated a challenging urban route using either landmarks or distance information to identify the location of forthcoming manoeuvres. A range of driver behaviour measures were collected, including visual glance data, driving errors, driver workload, navigation errors, navigation confidence, and pre and post-trial driver attitudinal responses. Results show that, for older and younger drivers, landmarks reduced the time spent glancing to a visual display, reduced navigation and driving errors, and influenced driver confidence. There were some key differences between the older and younger drivers. The wider implications for the design of in-car interfaces for the older driver are discussed.     

Factors associated with implementation of preventive care measures in patients with diabetes mellitus

BACKGROUND: There is only limited information on the extent to which physicians' characteristics affect the level of care and implementation of guidelines in patients with diabetes mellitus. OBJECTIVE: To identify physician characteristics associated with implementation of measures for preventive care in patients with diabetes mellitus and the distribution of implementation of these measures among them. PATIENTS AND METHODS: A retrospective chart audit of 519 patients eligible for health maintenance organization insurance on December 31, 1994, representing patients with diabetes receiving care from 22 primary care physician-providers of a managed care medical group in suburban North Los Angeles, Calif, and seen by physicians between January 1993 and December 1994. A short retroactive questionnaire for participating physicians was also used. The outcome measures were (1) measurement of serum high-density lipoprotein cholesterol; (2) urinalysis for the detection of proteinuria; and (3) ophthalmology referral for dilated fundus examination. RESULTS: Over a period of 2 years 78% of the patients had a high-density lipoprotein cholesterol determination, 80% had a test for proteinuria, and 62% were referred to an ophthalmologist. After adjustment for patient pool differences, physicians who were perceived by the administration of the medical group as "fast," based on a blinded evaluation of their number of patient encounters per unit time, had an odds ratio of 0.60 (95% confidence interval [CI], 0.37-0.95; P=.03) to obtain a high-density lipoprotein cholesterol determination in their patients and an odds ratio of 0.53 (95% CI, 0.32-0.87; P=.01) to test their patients for proteinuria. In patients requiring insulin, of fast physicians, the odds ratio for a referral for ophthalmology screening was 0.25 (95% CI, 0.07-0.85; P= .03). Duration of time in practice of over 15 years and disagreement with practice guidelines were associated with better outcomes. There was no association between physician sex, internal medicine training, or number of patients with diabetes in the practice and the implementation of outcomes. There was a highly significant association between the implementation of an outcome and the implementation of the other 2, resulting in a nonhomogeneous distribution of health care delivery. Physicians' estimate of their rate of implementation of outcomes, as assessed by the questionnaires, overestimated their actual performance while being in proportion with the documented rates. Most physicians took responsibility for the nonimplementation, accepting that it was an oversight on their part as opposed to an encounter with patient resistance. CONCLUSIONS: Most physicians believe that the lack of implementation of the measures for preventive care in patients with diabetes mellitus is an oversight. The oversight is more prevalent in the practices of busy physicians. The result is a nonhomogeneous distribution of health care. Computer reminders might be the solution.     

ECOLOGICAL RISK-ASSESSMENT METHODOLOGY: A UK CASE STUDY FOR LANDFILLS

The paper presents an ecological risk-assessment methodology which (a) addresses surface-water exposures to aquatic mammals and birds, and (b) accounts for long-term accumulation and biomagnification of pollutants. The methodology has been adapted from those developed in the USA for compliance with US Environmental Protection Agency requirements, and combines predicted or measured surface-water concentration data with information on the natural history of wildlife species and chemical-specific bioaccumulation factors, to determine whether estimated exposures would exceed toxicological criteria. Whilst the methodology is applied to metals in leachate discharges from landfill sites, the general approach is applicable to other industrial sites. The approach could provide the basis for a shift towards more numerical risk-based ecological assessments in a wide variety of contexts.     

The guideline interchange format: a model for representing guidelines

Carboxylate and sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by coating and immobilizing sodium 10-undecenoate (C11(:)) and 10-undecene sulfate (S11(:)) on the polymer by means of an argon plasma treatment. The composition of the coated surfactant layer was proportional to the composition of the coating solution. The thickness of the surfactant layer on the surface of PE samples, which were precoated from an aqueous solution with a total surfactant concentration of 0.30 M, was about 55 A. The presence of carboxylate and sulfate groups after plasma treatment of the precoated surfaces was confirmed by X-ray photoelectron spectroscopy (XPS). About 20% of the initial amount of functional groups of the coated surfactants was retained at the PE surface. The ratio of carboxylate/sulfate groups at the plasma treated surfaces was dependent on the composition of the precoated surfaces. The minimum surface density of these groups on the resulting samples was about one group per 40 A2.