2,014 research outputs found
Leg Sympathetic Response to Noxious Skin Stimuli is Similar in High and Low Level Human Spinal Cord Injury
Objective To determine if sympathetically mediated vasoconstriction in the lower extremities is injury level dependent. Although sympathetic responses have been measured in the limbs of people with high and low level SCI using blood flow measurements, including Doppler ultrasound and venous plethysmography, a direct comparison between injury levels has not been made. Methods Volunteers with chronic SCI were grouped according to injury level. Above T6: high level (HL, n = 7), and T6 and below: low level (LL, n = 6). All subjects had complete motor and sensory loss. Leg arterial flows were recorded by venous occlusion plethysmography, and continuous heart rate and mean arterial pressure (MAP) were measured. The conditioning stimulus consisted of transcutaneous stimulation to the arch of the contralateral foot. Results HL and LL subjects demonstrated a significant decrease in arterial conductance during stimulation with no significant difference found between groups. As expected, only group HL demonstrated a significant increase in MAP. Conclusions These results support our hypothesis that local (leg) sympathetic responses are similar for both high and low level SCI. Significance While low level SCI does not typically present with autonomic dysreflexia, bouts of increased reflex sympathetic activity could have ramifications for metabolism as well as renal and motor system functio
Leg Sympathetic Response to Noxious Skin Stimuli is Similar in High and Low Level Human Spinal Cord Injury
Objective To determine if sympathetically mediated vasoconstriction in the lower extremities is injury level dependent. Although sympathetic responses have been measured in the limbs of people with high and low level SCI using blood flow measurements, including Doppler ultrasound and venous plethysmography, a direct comparison between injury levels has not been made. Methods Volunteers with chronic SCI were grouped according to injury level. Above T6: high level (HL, n = 7), and T6 and below: low level (LL, n = 6). All subjects had complete motor and sensory loss. Leg arterial flows were recorded by venous occlusion plethysmography, and continuous heart rate and mean arterial pressure (MAP) were measured. The conditioning stimulus consisted of transcutaneous stimulation to the arch of the contralateral foot. Results HL and LL subjects demonstrated a significant decrease in arterial conductance during stimulation with no significant difference found between groups. As expected, only group HL demonstrated a significant increase in MAP. Conclusions These results support our hypothesis that local (leg) sympathetic responses are similar for both high and low level SCI. Significance While low level SCI does not typically present with autonomic dysreflexia, bouts of increased reflex sympathetic activity could have ramifications for metabolism as well as renal and motor system functio
Partial breakdown of quantum thermalization in a Hubbard-like model
We study the possible breakdown of quantum thermalization in a model of
itinerant electrons on a one-dimensional chain without disorder, with both spin
and charge degrees of freedom. The eigenstates of this model exhibit peculiar
properties in the entanglement entropy, the apparent scaling of which is
modified from a "volume law" to an "area law" after performing a partial,
site-wise measurement on the system. These properties and others suggest that
this model realizes a new, non-thermal phase of matter, known as a quantum
disentangled liquid (QDL). The putative existence of this phase has striking
implications for the foundations of quantum statistical mechanics.Comment: As accepted to PR
Controlling Great-Tailed Grackle Damage to Citrus in the Lower Rio Grande Valley, Texas
Great-tailed grackle (Quiscalus mexicanus) damage to citrus is a serious concern to producers in the lower Rio Grande Valley of Texas. Damage caused by grackles pecking fruit is initiated by breeding colonies in the spring on immature fruit and extends through the fall and winter on ripening fruit. The most significant damage occurs during the post-breeding period of July through September when neither the currently registered DRC-1339-treated dog food bait nor frightening strategies are effective. Observations by Texas Wildlife Services personnel suggested that watermelon was highly attractive to grackles during the period when dog food baits are poorly accepted. Two control strategies using watermelon to bait large cage traps and to formulate DRC-1339 baits were evaluated in cage and field trials during a 2-year research project. This paper reports on the development and preliminary evaluations of a unique trap design and the 0.1% DRC-1339-treated watermelon bait. Summer field trials in citrus groves were conducted to evaluate the effectiveness and safety of trapping and DRC-1339 baiting. Results of preliminary evaluations clearly demonstrated the utility of these methods for controlling grackles. Although the effectiveness of these methods for controlling grackle damage in citrus groves was less conclusive, no measurable hazards to non-target wildlife were documented. With suggested modifications, both methods may provide a viable means to reduce grackle damage to citrus during a period when other alternative methods are ineffective
Geometry of One-Dimensional Wave Propagation
We investigate the geometrical features of one-dimensional wave propagation,
whose dynamics is described by the (2+1)-dimensional Lorentz group. We find
many interesting geometrical ingredients such as spinorlike behavior of wave
amplitudes, gauge transformations, Bloch-type equations, and Lorentz-group
Berry phases. We also propose an optical experiment to verify these effects.Comment: RevTeX, 16 pages, 6 postscript figure
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