Spectral Properties of H-Reflex Recordings After an Acute Bout of Whole-Body Vibration

Although research supports the use of whole-body vibration (WBV) to improve neuromuscular performance, the mechanisms for these improvements remain unclear. The purpose of this study was to identify the effect ofWBV on the spectral properties of electrically evoked H-reflex recordings in the soleus (SOL) muscle. The H-reflex recordings were measured in the SOL muscle of 20 participants before and after a bout of WBV. The H-reflexes were evoked every 15 seconds for 150 seconds after WBV. A wavelet procedure was used to extract spectral data, which were then quantified with a principle components analysis. Resultant principle component scores were used for statistical analysis. The analysis extracted 1 principle component associated with the intensity of the myoelectric spectra and 1 principle component associated with the frequency. The scores of the principle component that were related to the myoelectric intensity were smaller at 30 and 60 milliseconds after WBV than before WBV. The WBV transiently decreased the intensity of myoelectric spectra during electrically evoked contractions, but it did not influence the frequency of the spectra. The decrease in intensity likely indicates a smaller electrically evoked muscle twitch response, whereas the lack of change in frequency would indicate a similar recruitment pattern of motor units before and after WBV

Probing the dynamic structure factor of a neutral Fermi superfluid along the BCS-BEC crossover using atomic impurity qubits

We study an impurity atom trapped by an anharmonic potential, immersed within a cold atomic Fermi gas with attractive interactions that realizes the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC). Considering the qubit comprising the lowest two vibrational energy eigenstates of the impurity, we demonstrate that its dynamics probes the equilibrium density fluctuations encoded in the dynamic structure factor of the superfluid. Observing the impurity's evolution is thus shown to facilitate nondestructive measurements of the superfluid order parameter and the contact between collective and single-particle excitation spectra. Our setup constitutes a novel model of an open quantum system interacting with a thermal reservoir, the latter supporting both bosonic and fermionic excitations that are also coupled to each other.Comment: Updated to final author version. 9+7 pages, 18 figure

Cultural background modulates how we look at other persons' gaze

The current study investigated the role of cultural norms on the development of face-scanning. British and Japanese adults’ eye movements were recorded while they observed avatar faces moving their mouth, and then their eyes toward or away from the participants. British participants fixated more on the mouth, which contrasts with Japanese participants fixating mainly on the eyes. Moreover, eye fixations of British participants were less affected by the gaze shift of the avatar than Japanese participants, who shifted their fixation to the corresponding direction of the avatar’s gaze. Results are consistent with the Western cultural norms that value the maintenance of eye contact, and the Eastern cultural norms that require flexible use of eye contact and gaze aversion

Plant genotype and environment interact to shape a diverse arthropod community on evening primrose (Oenothera biennis)

Both an individual's genotype and environment govern its phenotype, and this phenotype may have extended consequences for species interactions and communities. We examined the importance of plant genotype and environmental factors operating at large (habitat) and small (microhabitat) spatial scales in affecting a multitrophic arthropod community on plants. We planted 926 plants from 14 genotypes of Oenothera biennis into five natural habitats that represent the range of environments in which this plant locally occurs. Genotypic differences among plants accounted for as much as 41% of the variation in arthropod diversity (Simpson's diversity index) and also affected arthropod evenness, richness, abundance, and biomass on individual plants. However, the effects of particular plant genotypes on the arthropod community varied across habitats (i.e., there were significant plant genotype?by?habitat interactions). Plant genotype explained more variation in the arthropod community than did environmental variation among microhabitats, but less variation than habitats, as predicted by the scale?dependent hypothesis. Herbivores and omnivores were more strongly affected by plant genetic variation than predators, consistent with the notion that phytophagous insects undergo stronger reciprocal interactions with plants than do predators. We detected heritable variation in arthropod community variables and the ability for the herbivore community to select on plant traits, suggesting that evolution in O. biennis can lead to changes in the arthropod community. Genetic variation in plant size, architecture, and reproductive phenology were the plant traits most strongly correlated with arthropod community variables. Our results demonstrate that genotype?by?environment interactions are a major determinant of arthropod community structure.Our research is funded by Sigma Xi, Mountain Equipment Co?op Environment Fund, and the Natural Sciences and Engineering Research Council of Canada

Reduced neural sensitivity to social stimuli in infants at risk for autism

In the hope of discovering early markers of autism, attention has recently turned to the study of infants at risk owing to being the younger siblings of children with autism. Because the condition is highly heritable, later-born siblings of diagnosed children are at substantially higher risk for developing autism or the broader autism phenotype than the general population. Currently, there are no strong predictors of autism in early infancy and diagnosis is not reliable until around 3 years of age. Because indicators of brain functioning may be sensitive predictors, and atypical social interactions are characteristic of the syndrome, we examined whether temporal lobe specialization for processing visual and auditory social stimuli during infancy differs in infants at risk. In a functional near-infrared spectroscopy study, infants aged 4–6 months at risk for autism showed less selective neural responses to social stimuli (auditory and visual) than low-risk controls. These group differences could not be attributed to overall levels of attention, developmental stage or chronological age. Our results provide the first demonstration of specific differences in localizable brain function within the first 6 months of life in a group of infants at risk for autism. Further, these differences closely resemble known patterns of neural atypicality in children and adults with autism. Future work will determine whether these differences in infant neural responses to social stimuli predict either later autism or the broader autism phenotype frequently seen in unaffected family members

Virtual histology of transgenic mouse embryos for high-throughput phenotyping.

Journal ArticleA bold new effort to disrupt every gene in the mouse genome necessitates systematic, interdisciplinary approaches to analyzing patterning defects in the mouse embryo. We present a novel, rapid, and inexpensive method for obtaining high-resolution virtual histology for phenotypic assessment of mouse embryos. Using osmium tetroxide to differentially stain tissues followed by volumetric X-ray computed tomography to image whole embryos, isometric resolutions of 27 mum or 8 mum were achieved with scan times of 2 h or 12 h, respectively, using mid-gestation E9.5-E12.5 embryos. The datasets generated by this method are immediately amenable to state-of-the-art computational methods of organ patterning analysis. This technique to assess embryo anatomy represents a significant improvement in resolution, time, and expense for the quantitative, three-dimensional analysis of developmental patterning defects attributed to genetically engineered mutations and chemically induced embryotoxicity

Interplay between function and structure in complex networks

We show that abrupt structural transitions can arise in functionally optimal networks, driven by small changes in the level of transport congestion. Our results offer an explanation as to why so many diverse species of network structure arise in Nature (e.g. fungal systems) under essentially the same environmental conditions. Our findings are based on an exactly solvable model system which mimics a variety of biological and social networks. We then extend our analysis by introducing a novel renormalization scheme involving cost motifs, to describe analytically the average shortest path across multiple-ring-and-hub networks. As a consequence, we uncover a 'skin effect' whereby the structure of the inner multi-ring core can cease to play any role in terms of determining the average shortest path across the network.Comment: Expanded version of physics/0508228 with additional new result

Spinal Motor Control Differences between the Sexes

Activity-related knee joint dysfunction is more prevalent in females than males. One explanation for the discrepancy is differences in movement patterns between the sexes. However, the underlying mechanisms responsible for these differences remain unidentified. This study tested spinal motor control mechanisms influencing motor neuron pool output and subsequent muscle activation in 17 males and 17 females. The following variables were assessed at the soleus: the gain of the unconditioned H-reflex, gain of both intrinsic pre-synaptic inhibition (IPI) and extrinsic presynaptic inhibition (EPI), the level of recurrent inhibition (RI), the level of supraspinal drive determined by the ratio of the Vmax:Mmax (V-wave), electromechanical delay (EMD) and the rate of force development (RFD). The Wilks Lambda multivariate test of overall differences among groups was significant (p = 0.031). Univariate betweensubjects tests revealed males had greater RI (p = 0.042). However, the sexes did not differ on any of the other variables tested. In conclusion, the sexes differ on modulation of spinal motor control. Specifically, RI, a post-synaptic regulator of force output, was greater in males

Integrated Laboratory Demonstrations of Multi-Object Adaptive Optics on a Simulated 10-Meter Telescope at Visible Wavelengths

One important frontier for astronomical adaptive optics (AO) involves methods such as Multi-Object AO and Multi-Conjugate AO that have the potential to give a significantly larger field of view than conventional AO techniques. A second key emphasis over the next decade will be to push astronomical AO to visible wavelengths. We have conducted the first laboratory simulations of wide-field, laser guide star adaptive optics at visible wavelengths on a 10-meter-class telescope. These experiments, utilizing the UCO/Lick Observatory's Multi-Object / Laser Tomography Adaptive Optics (MOAO/LTAO) testbed, demonstrate new techniques in wavefront sensing and control that are crucial to future on-sky MOAO systems. We (1) test and confirm the feasibility of highly accurate atmospheric tomography with laser guide stars, (2) demonstrate key innovations allowing open-loop operation of Shack-Hartmann wavefront sensors (with errors of ~30 nm) as will be needed for MOAO, and (3) build a complete error budget model describing system performance. The AO system maintains a performance of 32.4% Strehl on-axis, with 24.5% and 22.6% at 10" and 15", respectively, at a science wavelength of 710 nm (R-band) over the equivalent of 0.8 seconds of simulation. The MOAO-corrected field of view is ~25 times larger in area than that limited by anisoplanatism at R-band. Our error budget is composed of terms verified through independent, empirical experiments. Error terms arising from calibration inaccuracies and optical drift are comparable in magnitude to traditional terms like fitting error and tomographic error. This makes a strong case for implementing additional calibration facilities in future AO systems, including accelerometers on powered optics, 3D turbulators, telescope and LGS simulators, and external calibration ports for deformable mirrors.Comment: 29 pages, 11 figures, submitted to PAS

Hazard Assessment of Personal Protective Clothing for Hydrogen Peroxide Service

Selection of personal protective equipment (PPE) for hydrogen peroxide service is an important part of the hazard assessment process. But because drip testing of chemical protective clothing for hydrogen peroxide service has not been reported for about 40 years, it is of great interest to test new protective clothing materials with new, high-concentration hydrogen peroxide following similar procedures. The suitability of PPE for hydrogen peroxide service is in part determined by observations made when hydrogen peroxide is dripped onto swatches of protective clothing material. Protective clothing material was tested as received, in soiled condition, and in grossly soiled condition. Materials were soiled by pretreating the material with potassium permanganate (KMnO4) solution then drying to promote a reaction. Materials were grossly soiled with solid KMnO4 to greatly promote reaction. Observations of results including visual changes to the hydrogen peroxide and materials, times to ignition, and self-extinguishing characteristics of the materials are reported