Some consequences of intense electromagnetic wave injection into space plasmas

The future possibility of actively testing the current understanding of how energetic particles may be accelerated in space or dumped from the radiation belts using intense electromagnetic energy from ground based antennas is discussed. The ground source of radiation is merely a convenience. A space station source for radiation that does not have to pass through the atmosphere and lower ionosphere, is an attractive alternative. The text is divided into two main sections addressing the possibilities of: (1) accelerating electrons to fill selected flux tubes above the Kennel-Petscheck limit for stably trapped fluxes, and (2) using an Alfven maser to cause rapid depletion of energetic protons or electrons from the radiation belts

Vibrotactile-auditory interactions are post-perceptual

Vibrotactile stimuli can elicit compelling auditory sensations, even when sound energy levels are minimal and undetectable. It has previously been shown that subjects judge auditory tones embedded in white noise to be louder when they are accompanied by a vibrotactile stimulus of the same frequency. A first experiment replicated this result at four different levels of auditory stimulation (no tone, tone at detection threshold, tone at 5 dB above threshold, and tone at 10 dB above threshold). The presence of a vibrotactile stimulus induced an increase in the perceived loudness of auditory tones at three of the four values in this range. In two further experiments, a 2-interval forced-choice procedure was used to assess the nature of this cross-modal interaction. Subjects were biased when vibrotaction was applied in one interval, but applying vibrotaction in both intervals produced performance comparable to conditions without vibrotactile stimuli. This demonstrates that vibrotaction is sometimes ignored when judging the presence of an auditory tone. Hence the interaction between vibrotaction and audition does not appear to occur at an early perceptual level

Proprioception in motor learning: : lessons from a deafferented subject

This document is the Accepted Manuscript version of the following article: N. Yousif, J. Cole, J. Rothwell, and J. Diedrichsen, ‘Proprioception in motor learning: lessons from a deafferented subject’, Experimental Brain Research, Vol. 233 (8): 2449-2459, August 2015. The final publication is available at Springer via https://doi.org/10.1007/s00221-015-4315-8.Proprioceptive information arises from a variety of channels, including muscle, tendon, and skin afferents. It tells us where our static limbs are in space and how they are moving. It remains unclear however, how these proprioceptive modes contribute to motor learning. Here, we studied a subject (IW) who has lost large myelinated fibres below the neck and found that he was strongly impaired in sensing the static position of his upper limbs, when passively moved to an unseen location. When making reaching movements however, his ability to discriminate in which direction the trajectory had been diverted was unimpaired. This dissociation allowed us to test the involvement of static and dynamic proprioception in motor learning. We found that IW showed a preserved ability to adapt to force fields when visual feedback was present. He was even sensitive to the exact form of the force perturbation, responding appropriately to a velocity- or position-dependent force after a single perturbation. The ability to adapt to force fields was also preserved when visual feedback about the lateral perturbation of the hand was withdrawn. In this experiment, however, he did not exhibit a form of use-dependent learning, which was evident in the control participants as a drift of the intended direction of the reaching movement in the perturbed direction. This suggests that this form of learning may depend on static position sense at the end of the movement. Our results indicate that dynamic and static proprioception play dissociable roles in motor learning.Peer reviewedFinal Accepted Versio

Proprioception in motor learning: : lessons from a deafferented subject

This document is the Accepted Manuscript version of the following article: N. Yousif, J. Cole, J. Rothwell, and J. Diedrichsen, ‘Proprioception in motor learning: lessons from a deafferented subject’, Experimental Brain Research, Vol. 233 (8): 2449-2459, August 2015. The final publication is available at Springer via https://doi.org/10.1007/s00221-015-4315-8.Proprioceptive information arises from a variety of channels, including muscle, tendon, and skin afferents. It tells us where our static limbs are in space and how they are moving. It remains unclear however, how these proprioceptive modes contribute to motor learning. Here, we studied a subject (IW) who has lost large myelinated fibres below the neck and found that he was strongly impaired in sensing the static position of his upper limbs, when passively moved to an unseen location. When making reaching movements however, his ability to discriminate in which direction the trajectory had been diverted was unimpaired. This dissociation allowed us to test the involvement of static and dynamic proprioception in motor learning. We found that IW showed a preserved ability to adapt to force fields when visual feedback was present. He was even sensitive to the exact form of the force perturbation, responding appropriately to a velocity- or position-dependent force after a single perturbation. The ability to adapt to force fields was also preserved when visual feedback about the lateral perturbation of the hand was withdrawn. In this experiment, however, he did not exhibit a form of use-dependent learning, which was evident in the control participants as a drift of the intended direction of the reaching movement in the perturbed direction. This suggests that this form of learning may depend on static position sense at the end of the movement. Our results indicate that dynamic and static proprioception play dissociable roles in motor learning.Peer reviewedFinal Accepted Versio

Michigan Production Costs for Tart Cherries by Production Region

The weighted average cost of producing tart cherries in Michigan on a representative farm in 2009 is $0.36/lb. This cost was averaged across the three main production regions in Michigan and weighted by average per acre production for each region as published by the Michigan Agricultural Statistics Service. --Costs vary across the main production regions and by farm size. Costs are about$0.04/lb less for mid-sized farms in Northwest Michigan and $0.08/lb and$0.10/lb in West Central and Southwest Michigan, respectively. --This report was developed through interviews with tart cherry growers and other experts in each of the three main growing regions in 2005 and 2006. Many of the numbers were updated in 2009. --The cost of production calculation is based on estimates of operating costs, harvest costs, and management, interest and tax costs. It also includes an amortized cost of establishing an orchard and employing the land in production (versus some other use). The following tables summarize the cost findings for each of the production regions.Tart cherry, costs, production, Michigan, Agribusiness, Crop Production/Industries, Q100, Q120,

Observing without acting: a balance of excitation and suppression in the human corticospinal pathway

Transcranial magnetic stimulation (TMS) studies of human primary motor cortex (M1) indicate an increase corticospinal excitability during the observation of another's action. This appears to be somewhat at odds with recordings of pyramidal tract neurons in primate M1 showing that there is a balance of increased and decreased activity across the population. TMS is known to recruit a mixed population of cortical neurons, and so one explanation for previous results is that TMS tends to recruit those excitatory output neurons whose activity is increased during action observation. Here we took advantage of the directional sensitivity of TMS to recruit different subsets of M1 neurons and probed whether they responded differentially to action observation in a manner consistent with the balanced change in activity in primates. At the group level we did not observe the expected increase in corticospinal excitability for either TMS current direction during the observation of a precision grip movement. Instead, we observed substantial inter-individual variability ranging from strong facilitation to strong suppression of corticospinal excitability that was similar across both current directions. Thus, we found no evidence of any differential changes in the excitability of distinct M1 neuronal populations during action observation. The most notable change in corticospinal excitability at the group level was a general increase, across muscles and current directions, when participants went from a baseline state outside the task to a baseline state within the actual observation task. We attribute this to arousal- or attention-related processes, which appear to have a similar effect on the different corticospinal pathways targeted by different TMS current directions. Finally, this rather non-specific increase in corticospinal excitability suggests care should be taken when selecting a "baseline" state against which to compare changes during action observation