Carrier Body Research Articles

Phoretic load of the parasitic mite Acarophenax lacunatus (Cross & Krantz) (Prostigmata: Acarophenacidae) affecting mobility and flight take-off of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Phoresy is the passive transport of an organism on the body of another from a different species, which is a beneficial adaptation for entomophagous arthropods to reach their hosts. Such an interaction occurs between the parasitic mite Acarophenax lacunatus (Prostigmata: Acarophenacidae) and its host, the lesser grain borer Rhyzopertha dominica (Coleoptera: Bostrichidae). Phoresy may have indirect effects in the host species determined by the number of phoretic individuals per carrier (phoretic load) and their distribution on the carrier's body. In the present study, the phoretic load and body distribution of A. lacunatus on adults of R. dominica was assessed. Also the potential interference of the above parameters with host mobility and flight take-off ability were evaluated. Phoretic load and body distribution were assessed by visual inspection under a stereomicroscope, while host mobility was assessed using a computer-automated tracking system. Flight take-off ability was assessed in crowed arenas (containing 50 insects each) at 30 °C. The observed mite load ranged from 1 to 11 mites/host, with a peak at around 5 mites/host. Among the host body parts, mites were mainly attached to the thorax (3.70 ± 0.17 mites), where attachment prevailed on the legs and metathorax. Host take-off ability was significantly decreased in the presence of high loads (>7 mites/host) of phoretic mites. Although high phoretic loads (>7 mites/insect) impaired host walking, phoretic loads between 4 and 6 mites/host appeared to favor host walking and consequently the surface dispersal of the parasitic mite.

Body Design of a Tracked Carrier

This paper describes the design of the light-class all terrain tracked carrier's body, developed by order given by STC Spectehnika MAMI. This design meets the modern technical requirements as well as terms of esthetics and ergonomics.

Attrition of the Charge on a Carrier Moving Through a Gas

Metallic, free-flying probes were used for sensing areas filled with weak concentration of free, unbalanced ambipolar charge or plasma, or for determining the charge on aerosols. Depending on the conditions, problems can be encountered in the behavior of the probe. This paper focuses on the charge exchange processes occurring between a small metal charge carrier and the gaseous medium through which the carrier travels; these processes may lead to a charge imbalance. In the experiments described, a small lead pellet was propelled with a small volume of pressurized carbon dioxide on a horizontal ballistic trajectory in air. At the launch site, the probe was charged by triboelectrification in a polytetrafluoroethylene tube, and its pre-and post flight charge measured with dynamic Faraday cups. The charge loss, incurred by the pellet crossing a 96 cm path (40 ms flight time), was 11%. Analysis of the results suggests that the onset of discharge from the carrier's body to the gas medium is a likely cause for the observed results.

Backpack Moment of Inertia Affects Oxygen Consumption During Walking

Prior research on the metabolic energy cost of carrying backpack loads has focused primarily on the effects of weight carried on the rate of oxygen consumption during walking. However, less research has been done on the effects of manipulating backpack mass center location or moment of inertia (MOI) on oxygen consumption. PURPOSE: The purpose of this study was to examine the effects of manipulating the MOI (distribution of mass about an axis of rotation) of a backpack load on the rate of oxygen consumption during walking. We hypothesized that varying the relationships among MOI values for the principal axes would differentially affect oxygen consumption. METHODS: Fourteen male volunteers participated in the study. Steel weights (26 kg total mass) were positioned in each of three military backpacks to produce different MO Is, but with the same mass (35 kg, inclusive of the backpack) and mass center locations (0.3 m posterior to the pack frame and 0.3 m superior to the bottom of the pack). The three packs differed in that each had the MOI of a unique principal axis (Ixx, Iyy, Izz) set at a small value (< 1.0 kg.m2), while the other two principal axes had large moments of inertia (> 2.0 kg.m2). Relative to the load carrier's body, Ixx, Iyy, and Izz defined the MOI about the anterior-posterior axis, the medial-lateral axis, and the vertical axis, respectively. The volunteers walked on a level treadmill at 4.8 km/h for 10 min carrying each of the packs. The rate of oxygen consumption (VO2) was recorded (COSMED K4b2, COSMED, Rome, Italy) during the last 90 sec of the walking period and was scaled to body plus load mass. A repeated measures ANO VA with three levels of MOI and follow-up comparisons were used to assess differences in the mean mass specific VO2. RESULTS: A significant difference (p < .05) in mean mass specific VO2 was found between the small Ixx value pack (15.04 ml/kg/min (SD 1.96)) and the small Iyy value pack (16.27 ml/kg/min (SD 2.09)). Mean differences approached statistical significance (p = .061) between the small Ixx pack and the small Izz pack (16.15 ml/kg/min (SD 2.23)). The small Iyy value and small Izz value packs did not statistically differ. CONCLUSION: The mean mass specific rate of oxygen consumption was 7.6% lower when Ixx was minimized relative to Iyy. Therefore, the metabolic energy cost of carrying backpack loads is not solely dependent on the amount of mass carried. The manner in which items are stowed in the backpack also affects metabolic energy expenditure and thus the physical endurance of the load carrier.

Best for Baby?

To the Editor: We would like to comment on “Device for Carrying a Physically Handicapped Child: Suggestion from the Field,” which was written by Jacqueline D. Mast (Physical Therapy, March 1985). We agree that it is important for parents and caretakers to have a means of transporting a child from place to place. We are concerned about effects that the recommended cloth carrier would have on a child with central nervous system damage. It is our experience that children with this disability most frequently require positioning that will inhibit capital and cervical hyperextension, scapular retraction, lower extremity extension and adduction, and plantar flexion. The carrier, by its design, facilitates scapular retraction, inhibits hands-to-midline, and allows hip and knee extension and plantar flexion. The contours of the carrier's body encourage trunk and cervical extension. On the positive side, the carrier does position the child's legs into abduction and free the child's and the caretaker's hands for activities. [ ARTICLE][1] [1]: /lookup/volpage/65/351?iss=3

On the transmission of brucei, rhodesiense, and gambiense by trypanosis by the Glossina fly after prolonged passage in laboratories

The author checked on a large material the position existing in the literature that trypanosomes from the brucei-rhodesiense-gambiense group lose their ability to develop in the carrier's body after long-term cultivation on media with blood. The study was carried out both on very old laboratory strains and on younger ones.