38 research outputs found
Activity of Pursuit-Related Neurons in Medial Superior Temporal Area (MST) during Static Roll-Tilt
Recent studies have shown that rhesus macaques can perceive visual motion direction in earth-centered coordinates as accurately as humans. We tested whether coordinate frames representing smooth pursuit and/or visual motion signals in medial superior temporal area (MST) are earth centered to better understand its role in coordinating smooth pursuit. In 2 Japanese macaques, we compared preferred directions (re monkeys' head–trunk axis) of pursuit and/or visual motion responses of MSTd neurons while upright and during static whole-body roll-tilt. In the majority (41/51 = 80%) of neurons tested, preferred directions of pursuit and/or visual motion responses were not significantly different while upright and during 40° static roll-tilt. Preferred directions of the remaining 20% of neurons (n = 10) were shifted beyond the range expected from ocular counter-rolling; the maximum shift was 14°, and the mean shift was 12°. These shifts, however, were still less than half of the expected shift if MST signals are coded in the earth-centered coordinates. Virtually, all tested neurons (44/46 = 96%) failed to exhibit a significant difference between resting discharge rate while upright and during static roll-tilt while fixating a stationary spot. These results suggest that smooth pursuit and/or visual motion signals of MST neurons are not coded in the earth-centered coordinates; our results favor the head- and/or trunk-centered coordinates
H2S biosynthesis and catabolism: new insights from molecular studies
Hydrogen sulfide (H2S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H2S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H2S within tissues. Studies utilising these systems are revealing new insights into the biology of H2S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H2S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H2S gas within tissue
Photometric follow-up of the transiting planetary system TrES-3: Transittiming variation and long-term stability of the system
We present new observations of the transiting system TrES-3 obtained from 2009 to 2011 at several observatories. The orbital parameters of the system were redetermined and a new linear ephemeris was calculated. The best quality light curve was used for light-curve analysis, and other data sets were used to determine mid-transit times (Tc) and study transit time variation (TTV). For planet parameter determination we used two independent codes and finally, we concluded that our parameters are in agreement with previous studies. Based on our observations, we determined 14 mid-transit times. Together with published TC, we found that the timing residuals showed no significant deviation from the linear ephemeris. We concluded that a periodic TTV signal with an amplitude greater than 1 min over a 4 yr time span seems to be unlikely. Our analysis of an upper mass limit allows us to exclude an additional Earth-mass planet close to inner 3:1, 2:1 and 5:3 and outer 3:5, 1:2 and 1:3 meanmotion resonances. Using the long-term integration and applying the method of maximum eccentricity, the region from 0.015 au to 0.05 au was found unstable and the region beyond the 0.05 au was found to have a chaotic behaviour and its depletion increases with increasing values of the initial eccentricity as well as inclination
Head roll dependent variability of subjective visual vertical and ocular counterroll
We compared the variability of the subjective visual vertical (SVV) and static ocular counterroll (OCR), and hypothesized a correlation between the measurements because of their shared macular input. SVV and OCR were measured simultaneously in various whole-body roll positions [upright, 45 degrees right-ear down (RED), and 75 degrees RED] in six subjects. Gains of OCR were -0.18 (45 degrees RED) and -0.12 (75 degrees RED), whereas gains of compensation for body roll in the SVV task were -1.11 (45 degrees RED) and -0.96 (75 degrees RED). Normalized SVV and OCR variabilities were not significantly different (P > 0.05), i.e., both increased with increasing roll. Moreover, a significant correlation (R (2) = 0.80, slope = 0.29) between SVV and OCR variabilities was found. Whereas the gain of OCR is different from the gain of SVV, trial-to-trial variability of OCR follows the same roll-dependent modulation observed in SVV variability. We propose that the similarities in variability reflect a common otolith input, which, however, is subject to distinct central processing for determining the gain of SVV and OCR
The Kosice meteorite fall: Recovery and strewn field
We provide the circumstances and details of the fireball observation, search
expeditions, recovery, strewn field, and physical characteristics of the Kosice meteorite that fell in Slovakia on February 28, 2010. The meteorite was only the 15th case of an observed bolide with a recovered mass and subsequent orbit determination. Despite multiple eyewitness reports of the bolide, only three videos from security cameras in Hungary were used for the strewn field determination and orbit computation. Multiple expeditions of professionals and individual searchers found 218 fragments with total weight of 11.3 kg. The
strewn field with the size of 593 km is characterized with respect to the space distribution of the fragments, their mass and size-frequency distribution. This work describes a catalog of 78 fragments, mass, size, volume, fusion crust, names of discoverers, geographic location, and time of discovery, which represents the most complex study of a fresh meteorite fall. From the analytical results, we classified the Kosice meteorite as an ordinary H5 chondrite