64 research outputs found
Variable Configuration Planner for Legged-Rolling Obstacle Negotiation Locomotion: Application on the CENTAURO Robot
Hybrid legged-wheeled robots are able to adapt their leg configuration and height to vary their footprint polygons and go over obstacles or traverse narrow spaces. In this paper, we present a variable configuration wheeled motion planner based on the A* algorithm. It takes advantage of the agility of hybrid wheeled-legged robots and plans paths over low-lying obstacles and in narrow spaces. By imposing a symmetry on the robot polygon, the computed plans lie in a low-dimensional search space that provides the robot with configurations to safely negotiate obstacles by expanding or shrinking its footprint polygon. The introduced autonomous planner is demonstrated using simulations and real-world experiments with the CENTAURO robot
The Evolution of Compact Binary Star Systems
We review the formation and evolution of compact binary stars consisting of
white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and
BHs are thought to be the primary astrophysical sources of gravitational waves
(GWs) within the frequency band of ground-based detectors, while compact
binaries of WDs are important sources of GWs at lower frequencies to be covered
by space interferometers (LISA). Major uncertainties in the current
understanding of properties of NSs and BHs most relevant to the GW studies are
discussed, including the treatment of the natal kicks which compact stellar
remnants acquire during the core collapse of massive stars and the common
envelope phase of binary evolution. We discuss the coalescence rates of binary
NSs and BHs and prospects for their detections, the formation and evolution of
binary WDs and their observational manifestations. Special attention is given
to AM CVn-stars -- compact binaries in which the Roche lobe is filled by
another WD or a low-mass partially degenerate helium-star, as these stars are
thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
Rapid Changes in the Light/Dark Cycle Disrupt Memory of Conditioned Fear in Mice
Background: Circadian rhythms govern many aspects of physiology and behavior including cognitive processes. Components of neural circuits involved in learning and memory, e.g., the amygdala and the hippocampus, exhibit circadian rhythms in gene expression and signaling pathways. The functional significance of these rhythms is still not understood. In the present study, we sought to determine the impact of transiently disrupting the circadian system by shifting the light/ dark (LD) cycle. Such ‘‘jet lag’ ’ treatments alter daily rhythms of gene expression that underlie circadian oscillations as well as disrupt the synchrony between the multiple oscillators found within the body. Methodology/Principal Findings: We subjected adult male C57Bl/6 mice to a contextual fear conditioning protocol either before or after acute phase shifts of the LD cycle. As part of this study, we examined the impact of phase advances and phase delays, and the effects of different magnitudes of phase shifts. Under all conditions tested, we found that recall of fear conditioned behavior was specifically affected by the jet lag. We found that phase shifts potentiated the stress-evoked corticosterone response without altering baseline levels of this hormone. The jet lag treatment did not result in overall sleep deprivation, but altered the temporal distribution of sleep. Finally, we found that prior experience of jet lag helps to compensate for the reduced recall due to acute phase shifts. Conclusions/Significance: Acute changes to the LD cycle affect the recall of fear-conditioned behavior. This suggests that
Knowledge, Attitude and Practice on Blood Donation among Health Science Students in a University campus, South India
Background: The major part of demand for blood in India has been meeting through voluntary blood donations. The healthy, active and receptive huge student population is potential blood donors to meet safe blood requirements. However, there is a paucity of studies on awareness and attitude among health science students on voluntary blood donation. Objective: The objective of this study was to determine the knowledge and attitude about blood donation among health science students. Methods: A cross-sectional study was conducted among 410 health sciences students from different streams in a University campus of South India through a structured survey questionnaire in the year 2009. Results: The overall knowledge on blood donation was good, but majority (62%) of students never donated blood. Knowledge level was found highest among allied health science (53.1%) and lowest among pharmacy students (20.7%). ‘Feeling of medically unfit’ and ‘never thought of blood donation’ were the major reasons for not donating blood. A significant association was observed between different streams of students and levels of knowledge and attitude about blood donation. Conclusion: This study elicits the importance of adopting effective measures in our campuses to motivate about voluntary blood donation among students
Agile Legged-Wheeled Reconfigurable Navigation Planner Applied on the CENTAURO Robot
Hybrid legged-wheeled robots such as the CEN-TAURO, are capable of varying their footprint polygon to carry out various agile motions. This property can be advantageous for wheeled-only planning in cluttered spaces, which is our focus. In this paper, we present an improved algorithm that builds upon our previously introduced preliminary footprint varying A* planner, which was based on the rectangular symmetry of the foot support polygon. In particular, we introduce a Theta* based planner with trapezium-like search, which aims to further reduce the limitations imposed upon the wheeled-only navigation of the CENTAURO robot by the low-dimensional search space, maintaining the real-time computational efficiency. The method is tested on the simulated and real full-size CENTAURO robot in cluttered environments
LASERS : A BOON IN THE MANAGEMENT OF TEMPOROMANDIBULAR DISORDERS
Temporomandibular disorders have been identified as the most important cause of pain in the facial region. Pain relief and reestablishment of normal masticatory function are the main goals of conservative management of Temporomandibular Disorders (TMD). Laser therapy is a part of the treatment modality that have demonstrated to have an analgesic, anti-inflammatory and biostimulating effect. The LLLT is a non invasive , quick and safe, non pharmacological intervention that may be beneficial for patient with TMDs. This review article projects the use of LLLT for management of temporomandibular disorders ,its mode of action and also gives a review on various studies conducted to assess its efficacy on pain management
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