Single-particle dispersion in stably stratified turbulence

We present models for single-particle dispersion in vertical and horizontal directions of stably stratified flows. The model in the vertical direction is based on the observed Lagrangian spectrum of the vertical velocity, while the model in the horizontal direction is a combination of a continuous-time eddy-constrained random walk process with a contribution to transport from horizontal winds. Transport at times larger than the Lagrangian turnover time is not universal and dependent on these winds. The models yield results in good agreement with direct numerical simulations of stratified turbulence, for which single-particle dispersion differs from the well studied case of homogeneous and isotropic turbulence

Optometric trends in sports vision: Knowledge, utilization, and practitioner role expansion potential in 1994

Background: The optometric discipline of sports vision is a relatively young and actively growing area which has spurred the interest of optometrists and sports organizations at all levels of athletics. Methods: 473 optometrists were surveyed and compared to a similar survey sent to 100 optometrists in 1980, 1983, and the same 473 in 1987-88. Also, 290 college and 108 professional teams were surveyed. Results: Optometrists felt there were more opportunities available in sports vision. Contact lenses are preferred over spectacles for most general sports, and optometrists usually consider the specific visual demands of the athlete when providing services. Vision therapy was reported to be used in nearly half the practices surveyed. College and professional team results suggest a broader acceptance and utilization of sports vision services. Conclusions: Since the establishment of the American Optometric Association Sports Vision Section (AOA-SVS) seventeen years ago, advances have been made in utilization and acceptance worldwide. The results of this survey, however, show that there. is still an unmet need for vision care and screening services at both the collegiate and professional levels

Ultrastructure of grape leaf protoplasts in comparison with the source tissue

Based on their histochemical properties, protoplasts from grape leaf mesophyll were found to be viable and devoid of remnants of the cell wall. The results were confirmed by electron microscopy of sectioned and freeze-etched protoplast preparations. The only remarkable difference between cells in the intact tissue and the protoplasts was the occurrence of electron-dense globules in the cytoplasm of some individuals. These "osmiophilic bodies" are believed to be due to inevitable plasmolytic effects during wall removal and seem not to have any influence on protoplast CO2-assimilation, as has been demonstrated earlier. lt therefore appears that the vital structures remain intact and functional, in spite of the stress situation created by the isolation procedure.Ultrastruktur von Rebenblatt-Protoplasten und Ausgangsgewebe - ein VergleichAnhand histochemischer Nachweise, welche das Weiterfunktionieren der Plasmamembran als physiologische Barriere nach dem Isolationsprozeß bestätigen, können Mesophyllprotoplasten von Vitis vinifera L. als lebensfähig betrachtet werden. Dieser Befund, sowie das vollständige Fehlen von Zellwandresten, wurde durch elektronenmikroskopische Untersuchungen an Ultradünnschnitten bzw. Gefrierätzproben von Protoplastenpräparaten erhärtet. Das vereinzelte Auftreten von elektronendichten, runden Gebilden (sog. osmiophilic bodies) im Cytoplasma ist vermutlich eine der plasmolysierenden Wirkung des Isolationsmediums zuzuschreibende Erscheinung. Wie früher gezeigt, hat aber die verwendete Isolationsmethodik keinen negativen Einfluß auf den photosynthetischen C-Stoffwechsel der Protoplasten. Daraus geht hervor, daß die lebenswichtigen Zellkomponenten, trotz der isolationsbedingten Streßsituation, keinen irreversiblen und damit nachweisbaren, strukturellen oder funktionellen Beeinträchtigungen unterworfen sind

Green Fluorescent Protein in the sea urchin: new experimental approaches to transcriptional regulatory analysis in embryos and larvae

The use of Green Fluorescent Protein (GFP) as a reporter for expression transgenes opens the way to several new experimental strategies for the study of gene regulation in sea urchin development. A GFP coding sequence was associated with three different previously studied cis-regulatory systems, viz those of the SM50 gene, expressed in skeletogenic mesenchyme, the CyIIa gene, expressed in archenteron, skeletogenic and secondary mesenchyme, and the Endo16 gene, expressed in vegetal plate, archenteron and midgut. We demonstrate that the sensitivity with which expression can be detected is equal to or greater than that of whole-mount in situ hybridization applied to detection of CAT mRNA synthesized under the control of the same cis-regulatory systems. However, in addition to the important feature that it can be visualized nondestructively in living embryos, GFP has other advantages. First, it freely diffuses even within fine cytoplasmic cables, and thus reveals connections between cells, which in sea urchin embryos is particularly useful for observations on regulatory systems that operate in the syncytial skeletogenic mesenchyme. Second, GFP expression can be dramatically visualized in postembryonic larval tissues. This brings postembryonic larval developmental processes for the first time within the easy range of gene transfer analyses. Third, GFP permits identification and segregation of embryos in which the clonal incorporation of injected DNA has occurred in any particular desired region of the embryo. Thus, we show explicitly that, as expected, GFP transgenes are incorporated in the same nuclei together with other transgenes with which they are co-injected

Wavelet Decomposition of Forced Turbulence: Applicability of the Iterative Donoho-Johnstone Threshold

We examine the decomposition of forced Taylor-Green and Arn’old-Beltrami- Childress (ABC) flows into coherent and incoherent components using an orthonormal wavelet decomposition. We ask whether wavelet coefficient thresh- olding based on the Donoho-Johnstone criterion can extract a coherent vortex signal while leaving behind Gaussian random noise. We find that no threshold yields a strictly Gaussian incoherent component, and that the most Gaussian incoherent flow is found for data compression lower than that achieved with the fully iterated Donoho-Johnstone threshold. Moreover, even at such low compression, the incoherent component shows clear signs of large-scale spatial correlations that are signatures of the forcings used to drive the flows

Cost avoidance realized through transportation and disposal of Fernald mixed low-level waste

Currently, Department of Energy (DOE) facilities are undergoing a transformation from shipping radiologically contaminated waste within the DOE structure for disposal to now include Mixed Low Level Waste (MLLW) shipments to a permitted commercial disposal facility (PCDF) final disposition. Implementing this change can be confusing and is perceived as being more difficult than it actually is. Lack of experience and disposal capacity, sometimes and/or confusing regulatory guidance, and expense of transportation and disposal of MLLW ar contributing factors to many DOE facilities opting to simply store their MLLW. Fernald Environmental Restoration Management Company (FERMCO) established itself as a leader i addressing MLLW transportation and disposal by being one of the first DOE facilities to ship mixed waste to a PCDF (Envirocare of Utah) for disposal. FERMCO`s proactive approach in establishing a MLLW Disposal Program produces long-term cost savings while generating interim mixed waste storage space to support FERMCO`s cleanup mission. FERMCO`s goal for all MLLW shipments was to develop a cost efficient system to accurately characterize, sample and analyze the waste, prepare containers and shipping paperwork, and achieve regulatory compliance while satisfying disposal facility waste acceptance criteria (WAC). This goal required the ability to evolve with the regulations, to address waste streams of varying matrices and contaminants, and to learn from each MLLW shipment campaign. These efforts have produced a successful MLLW Disposal Program at the Fernald Environmental Management Project (FEMP). FERMCO has a massed lessons learned from development of this fledgling program which may be applied complex-wide to ultimately save facilities time and money traditionally wasted by maintaining the status quo

Step Aerobics: A Kinematic And Kinetic Analysis

Step aerobics has become a popular form of aerobic exercise. Information regarding the mechanical stresses on the lower extremity during step aerobics may guide in determining the factors contributing to the risk of injury during progressions within this activity. Therefore, the purpose of this study was to investigate selected kinematic and kinetic variables during step aerobics at three heights and two cadences. Nine female subjects, mean age of 25.22 ± 4.3 yrs and mean height of 164 . 81 ±4.5 cm, performed conventional step aerobics. A conventional step was defined as right foot up, left foot up, right foot down, and left foot down. Three step heights of 4,6, and 8 in. and two cadences of 100 and 120 steps/minute (SPM) were performed by each subject in random order. These conditions were similar to those used in a typical step aerobics class. High speed cinematographic data collected at 90 frames/second were used to determine 2-D coordinates of the right leg in the sagittal plane. A Kistler force platform was used to measure ground reaction forces (GRF) of the right foot during step down. Identical mean vertical peak GRF were observed for both cadences. These forces were 1. 60, 1 .66, and 1 .76 percent body weight, at 4,6, and 8 in. respectively. Thus, increasing cadence from 100 to 120 SPM did not increase the risk of experiencing higher GRF in the lower extremity. Significant differences were found only between compressive joint forces and step heights at the ankle, knee, and hip. The magnitude of these joint forces were similar, indicating that there was no dissipation of forces throughout the lower extremity, unlike what has been observed during walking and running. Examination of the knee and hip moments revealed oscillating patterns that varied at different heights and cadences. This may indicate that these joints were used uniquely by individuals in stabilization of the body during the step down phase. With the possible exception of injury due to the lack of force dissipation, these findings suggest that progression of height and/or cadence may not be risk factors contributing to injury

3D photospheric velocity field of a Supergranular cell

We investigate the plasma flow properties inside a Supergranular (SG) cell, in particular its interaction with small scale magnetic field structures. The SG cell has been identified using the magnetic network (CaII wing brightness) as proxy, applying the Two-Level Structure Tracking (TST) to high spatial, spectral and temporal resolution observations obtained by IBIS. The full 3D velocity vector field for the SG has been reconstructed at two different photospheric heights. In order to strengthen our findings, we also computed the mean radial flow of the SG by means of cork tracing. We also studied the behaviour of the horizontal and Line of Sight plasma flow cospatial with cluster of bright CaII structures of magnetic origin to better understand the interaction between photospheric convection and small scale magnetic features. The SG cell we investigated seems to be organized with an almost radial flow from its centre to the border. The large scale divergence structure is probably created by a compact region of constant up-flow close to the cell centre. On the edge of the SG, isolated regions of strong convergent flow are nearby or cospatial with extended clusters of bright CaII wing features forming the knots of the magnetic network.Comment: 7 pages, submitted to A&A, referee's comments include

A modified version of the Bayley Scales of Infant Development-II for cognitive matching of infants with and without Down syndrome

Background Many measures of infants' early cognitive development, including the BSID-II (The Bayley Scales of Infant Development), mix together test items that assess a number of different developmental domains including language, attention, motor functioning and social abilities, and some items contribute to the assessment of more than one domain. Consequently, the scales may lead to under- or over-estimates of cognitive abilities in some clinical samples and may not be the best measure to use for matching purposes. Method To address this issue we created a modified form of the BSID-II (the BSID-M) to provide a ‘purer’ assessment of the general cognitive capacities in infants with Down syndrome (DS) from 6 to 18 months of age. We excluded a number of items that implicated language, motor, attentional and social functioning from the original measure. This modified form was administered to 17 infants with Down syndrome when 6, 12 and 18 months old and to 41 typically developing infants at 4, 7 and 10 months old. Results The results suggested that the modified form continued to provide a meaningful and stable measure of cognitive functioning and revealed that DS infants may score marginally higher in terms of general cognitive abilities when using this modified form than they might when using the standard BSID-II scales. Conclusions This modified form may be useful for researchers who need a ‘purer’ measure with which to match infants with DS and other infants with intellectual disabilities on cognitive functioning