942 resultados para ARM COORDINATION


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Aim. External fertilisation requires synchronisation of gamete release between the two sexes. Adequate synchronisation is essential in aquatic media because sperm is very short-lived in water. In the cichlid Lamprologus callipterus, fertilisation of the eggs takes place inside an empty snail shell, where females stay inside the shell and males have to ejaculate into the shell opening. This spawning pattern makes the coordination of gamete release difficult. Methods. This study examined the synchronisation of males and females during egg laying. Results. The results showed that the male initiates each spawning sequence and that sperm release and egg laying are very well synchronised. 68% of all sperm releases occurred at exactly the same time when the female laid an egg, and 99% of ejaculations occurred within ±5 seconds from egg deposition. On average 95 eggs are laid one by one with intervals of several minutes between subsequent eggs, leading to a total spawning duration in excess of six hours. Conclusions. We discuss this exceptional spawning pattern and how it might reflect a conflict between the sexes, with males attempting to induce egg laying and females extending the egg laying period to raise the chance for parasitic males to participate in spawning.

Relevância:

20.00% 20.00%

Publicador:

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Bucknell Humanoid Robot Arm project was developed in order toprovide a lightweight robotic arm for the IHMC / Bucknell University bipedal robot that will provide a means of manipulation and facilitate operations in urban environments. The resulting fabricated arm described in this thesis weighs only 13 pounds, and is capable of holding 11 pounds fully outstretched, lifting objects such as tools, and it can open doors. It is also capable of being easily integrated with the IHMC / Bucknell University biped. This thesis provides an introduction to robots themselves, discusses the goals of the Bucknell Humanoid Robot Arm project, provides a background on some of the existing robots, and shows how the Bucknell Humanoid Robot Arm fits in with the studies that have been completed. After reading these studies, important items such as design trees and operational scenarios were completed. The completion of these items led to measurable specifications and later the design requirements and specifications. A significant contribution of this thesis to the robotics discipline involves the design of the actuator itself. The arm uses of individual, lightweight, compactly designed actuators to achieve desired capabilities and performance requirements. Many iterations were completed to get to the final design of each actuator. After completing the actuators, the design of the intermediate links and brackets was finalized. Completion of the design led to the development of a complex controls system which used a combination of Clanguage and Java.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

OBJECTIVE: The aim of this study was to evaluate the feasibility of a clinical trial investigating the effects of acupuncture (AP) and Chinese herbal medicine (CHM) on hot flushes and quality of life in postmenopausal women. METHODS: Forty postmenopausal women reporting at least 20 hot flushes per week were enrolled in a randomized controlled trial. They were randomly allocated to receive traditional Chinese medicine (TCM) AP, sham AP, verum CHM, or placebo CHM for 12 weeks. Follow-up assessment was conducted 12 weeks after intervention. Primary outcome measures included hot flush frequency and severity. As a secondary outcome measure, the severity of menopausal symptoms was assessed using the Menopause Rating Scale (MRS) II. RESULTS: TCM AP induced a significant decline in all outcome measures from pretreatment to posttreatment compared with sham AP (hot flush frequency, P = 0.016; hot flush severity, P = 0.013; MRS, P < 0.001). In the TCM AP group, a larger decrease in MRS scores persisted from pretreatment to follow-up (P = 0.048). No significant differences were noted between the verum CHM group and the placebo CHM group. Compared with the verum CHM group, there was a significant decrease in MRS scores (P = 0.002) and a trend toward a stronger decrease in hot flush severity (P = 0.06) in the TCM AP group from pretreatment to posttreatment. CONCLUSIONS: TCM AP is superior to sham AP and verum CHM in reducing menopausal symptoms, whereas verum CHM shows no significant improvements when compared with placebo CHM.

Relevância:

20.00% 20.00%

Publicador: