797 research outputs found
Record of Anthophora (Clisodon) terminalis in a wooden trap-nesting block and comparison to available nesting information (Hymenoptera: Apidae)
Bee nesting substrate choice can influence habitat use, conservation effort efficacy, and population or landscape-use modeling, but information on nesting sites are often scattered in the literature. Here we bring together the available information on nests of a widespread bee, Anthophora (Clisodon) terminalis Cresson, and describe an unusual new nesting substrate use for this species
Megachile (Megachile) montivaga (Hymenoptera: Megachilidae) nesting in live thistle (Asteraceae: Cirsium)
Although Megachile Latreille (leafcutter bees) are well known for their diverse nesting habits, records of the genus nesting in live plants are rare. Here, we report the widespread Megachile (Megachile) montivaga Cresson nesting in live thistle (Cirsium neomexicanum Gray), the first explicit record of this behavior in the Nearctic
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Brain activation during execution and motor imagery of novel and skilled sequential hand movements.
This experiment used functional magnetic resonance imaging (fMRI) to compare functional neuroanatomy associated with executed and imagined hand movements in novel and skilled learning phases. We hypothesized that 1 week of intensive physical practice would strengthen the motor representation of a hand motor sequence and increase the similarity of functional neuroanatomy associated with executed and imagined hand movements. During fMRI scanning, a right-hand self-paced button press sequence was executed and imagined before (NOVEL) and after (SKILLED) 1 week of intensive physical practice (n = 54; right-hand dominant). The mean execution rate was significantly faster in the SKILLED (3.8 Hz) than the NOVEL condition (2.5 Hz) (P < 0.001), but there was no difference in execution errors. Activation foci associated with execution and imagery was congruent in both the NOVEL and SKILLED conditions, though activation features were more similar in the SKILLED versus NOVEL phase. In the NOVEL phase, activations were more extensive during execution than imagery in primary and secondary cortical motor volumes and the cerebellum, while during imagery activations were greater in the striatum. In the SKILLED phase, activation features within these same volumes became increasingly similar for execution and imagery, though imagery more heavily activated premotor areas, inferior parietal lobe, and medial temporal lobe, while execution more heavily activated the precentral/postcentral gyri, striatum, and cerebellum. This experiment demonstrated congruent activation of the cortical and subcortical motor system during both novel and skilled learning phases, supporting the effectiveness of motor imagery-based mental practice techniques for both the acquisition of new skills and the rehearsal of skilled movements
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Effects of motor imagery training after chronic, complete spinal cord injury.
Abnormalities in brain motor system function are present following spinal cord injury (SCI) and could reduce effectiveness of restorative interventions. Motor imagery training, which can improve motor behavior and modulate brain function, might address this concern but has not been examined in subjects with SCI. Ten subjects with SCI and complete tetra-/paraplegia plus ten healthy controls underwent assessment before and after 7 days of motor imagery training to tongue and to foot. Motor imagery training significantly improved the behavioral outcome measure, speed of movement, in non-paralyzed muscles. Training was also associated with increased fMRI activation in left putamen, an area associated with motor learning, during attempted right foot movement in both groups, despite foot movements being present in controls and absent in subjects with SCI. This fMRI change was absent in a second healthy control group serially imaged without training. In subjects with SCI, training exaggerated, rather than normalized, baseline derangement of left globus pallidus activation. The current study found that motor imagery training improves motor performance and alters brain function in subjects with complete SCI despite lack of voluntary motor control and peripheral feedback. These effects of motor imagery training on brain function have not been previously described in a neurologically impaired population, and were similar to those found in healthy controls. Motor imagery might be of value as one component of a restorative intervention
Paper Session I-A - Unmanned Aerial Vehicles as Technology Demonstrators for Advanced Range Systems
This project consists of the development and operation of an unmanned aerial vehicle (UAV) as a technology demonstration test bed for advanced range systems under development at Kennedy Space Center. The goal is to acquire a reliable, rapidly accessible vehicle for initial flight testing of electronic payloads through a limited portion of airspace to verify basic communications, command and control, tracking, and telemetry functions. The cost and schedule benefits of the project should exceed the other available options of flight in actual manned aircraft or sounding rockets.
The vehicle will be remotely piloted with a reliable command and control system independent of the devices under test. It must account for any failure modes, and have contingencies to maximize safety of the operations. The UAV will provide standardized mounting, protection, and power to the devices under test. Considerations of airspace, FAA regulations, and authorizations for UAV operations must be thoroughly evaluated.
This rapid demonstration capability will expedite development and initial. testing of advanced range systems projects, and provide gains in overall UAV knowledge, at a reasonable cost. The project fits well within existing ARTWG (Advanced Range Technology Working Group) Roadmaps for the future of Range Systems
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Cortical activation during executed, imagined, and observed foot movements.
Evidence suggests that executed, imagined, and observed movements share neural substrates, however, brain activation during the performance of these three tasks has not yet been examined during lower extremity movements. Functional MRI was performed in 10 healthy right-footed participants during imagined, executed, and observed right ankle movements. Task compliance was high, confirmed via behavioral assessment and electromyographic measurements. Each task was also associated with its own profile of regional activation, however, overall, regional activation showed substantial overlap across the three lower extremity motor tasks. The findings suggest the utility of continued efforts to develop motor imagery and observation programs for improving lower extremity function in a range of clinical settings
Assessing the Accuracy of Complex Refractive Index Retrievals from Single Aerosol Particle Cavity Ring-Down Spectroscopy
<p>Cavity ring-down spectroscopy (CRDS) of single, optically manipulated aerosol particles affords quantitative retrieval of refractive indices for particles of fixed or evolving composition with high precision. Here, we quantify the accuracy with which refractive index determinations can be made by CRDS for single particles confined within the core of a Bessel laser beam and how that accuracy is degraded as the particle size is progressively reduced from the coarse mode (>1 μm radius) to the accumulation mode (<500 nm radius) regime. We apply generalized Lorenz–Mie theory to the intra-cavity standing wave to explore the effect of particle absorption on the distribution of extinction cross section determinations resulting from stochastic particle motion in the Bessel beam trap. The analysis provides an assessment of the accuracy with which the real, <i>n</i>, and imaginary, κ, components of the refractive index can be determined for a single aerosol particle.</p> <p>Published with license by American Association for Aerosol Research</p> <p><a href="https://www.tandfonline.com/pb-assets/tandf/Migrated/UAST_VideoAbstract_Transcript.pdf" target="_blank">Read the transcript</a></p> <p><a href="https://vimeo.com/263371383" target="_blank">Watch the video on Vimeo</a></p
A comparison of two statistical postprocessing methods for heavy-precipitation forecasts over India during the summer monsoon
Accurate ensemble forecasts of heavy precipitation in India are vital for many applications and essential for early warning of damaging flood events, especially during the monsoon season. In this study we investigate to what extent Quantile Mapping (QM) and Ensemble Model Output Statistics (EMOS) statistical postprocessing reduce errors in precipitation ensemble forecasts over India, in particular for heavy precipitation. Both methods are applied to day-1 forecasts at 12-km resolution from the 23-member National Centre for Medium Range Weather Forecasting (NCMRWF) global ensemble prediction system (NEPS-G). By construction, QM leads to distributions close to the observed ones, while EMOS optimizes the ensemble spread, and it is not a priori clear which is better suited for practical applications. The methods are therefore compared with respect to several key aspects of the forecasts: local distributions, ensemble spread, and skill for forecasting precipitation amounts and the exceedance of heavy-precipitation thresholds. The evaluation includes rank histograms, Continuous Ranked Probability Skill Scores (CRPSS), Brier Skill Scores (BSS), reliability diagrams, and receiver operating characteristic. EMOS performs best not only with respect to correcting under- or overdispersive ensembles, but also in terms of forecast skill for precipitation amounts and heavy precipitation events, with positive CRPSS and BSS in most regions (both up to about 0.4 in some areas), while QM in many regions performs worse than the raw forecast. QM performs best with respect to the overall local precipitation distributions. Which aspects of the forecasts are most relevant depends to some extent on how the forecasts are used. If the main criteria are the correction of under- or overdispersion, forecast reliability, match between the forecasted distribution for individual days and observations (CRPSS), and the skill in forecasting heavy-precipitation events (BSS), then EMOS is the better choice for postprocessing NEPS-G forecasts for short lead times
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