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

Realistic Magnetohydrodynamical Simulation of Solar Local Supergranulation

Three-dimensional numerical simulations of solar surface magnetoconvection using realistic model physics are conducted. The thermal structure of convective motions into the upper radiative layers of the photosphere, the main scales of convective cells and the penetration depths of convection are investigated. We take part of the solar photosphere with size of 60x60 Mm in horizontal direction and by depth 20 Mm from level of the visible solar surface. We use a realistic initial model of the Sun and apply equation of state and opacities of stellar matter. The equations of fully compressible radiation magnetohydrodynamics with dynamical viscosity and gravity are solved. We apply: 1) conservative TVD difference scheme for the magnetohydrodynamics, 2) the diffusion approximation for the radiative transfer, 3) dynamical viscosity from subgrid scale modeling. In simulation we take uniform two-dimesional grid in gorizontal plane and nonuniform grid in vertical direction with number of cells 600x600x204. We use 512 processors with distributed memory multiprocessors on supercomputer MVS-100k in the Joint Computational Centre of the Russian Academy of Sciences.Comment: 6 pages, 5 figures, submitted to the proceedings of the GONG 2008 / SOHO XXI conferenc

Numerical simulations of compressible Rayleigh-Taylor turbulence in stratified fluids

We present results from numerical simulations of Rayleigh-Taylor turbulence, performed using a recently proposed lattice Boltzmann method able to describe consistently a thermal compressible flow subject to an external forcing. The method allowed us to study the system both in the nearly-Boussinesq and strongly compressible regimes. Moreover, we show that when the stratification is important, the presence of the adiabatic gradient causes the arrest of the mixing process.Comment: 15 pages, 11 figures. Proceedings of II Conference on Turbulent Mixing and Beyond (TMB-2009

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

Low level waste shipment accident lessons learned

On October 1, 1994 a shipment of low-level waste from the Fernald Environmental Management Project, Fernald, Ohio, was involved in an accident near Rolla, Missouri. The accident did not result in the release of any radioactive material. The accident did generate important lessons learned primarily in the areas of driver and emergency response communications. The shipment was comprised of an International Standards Organization (ISO) container on a standard flatbed trailer. The accident caused the low-level waste package to separate from the trailer and come to rest on its top in the median. The impact of the container with the pavement and median inflicted relatively minor damage to the container. The damage was not substantial enough to cause failure of container integrity. The success of the package is attributable to the container design and the packaging procedures used at the Fernald Environmental Management Project for low-level waste shipments. Although the container survived the initial wreck, is was nearly breached when the first responders attempted to open the ISO container. Even though the container was clearly marked and the shipment documentation was technically correct, this information did not identify that the ISO container was the primary containment for the waste. The lessons learned from this accident have DOE complex wide applicability. This paper is intended to describe the accident, subsequent emergency response operations, and the lessons learned from this incident

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

Bilayer Splitting in the Electronic Structure of Heavily Overdoped Bi2Sr2CaCu2O8+d

The electronic structure of heavily overdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ is investigated by angle-resolved photoemission spectroscopy. The long-sought bilayer band splitting in this two-plane system is observed in both normal and superconducting states, which qualitatively agrees with the bilayer Hubbard model calculations. The maximum bilayer energy splitting is about 88 meV for the normal state feature, while it is only about 20 meV for the superconducting peak. This anomalous behavior cannot be reconciled with the quasiparticle picture.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

Quasiparticle Liquid in the Highly Overdoped Bi2212

We present results from the study of a highly overdoped (OD) Bi2212 with a $T_{c}=51$K using high resolution angle-resolved photoemission spectroscopy. The temperature dependent spectra near the ($\pi,0$) point show the presence of the sharp peak well above $T_{c}$. From the nodal direction, we make comparison of the self-energy with the optimally doped and underdoped cuprates, and the Mo(110) surface state. We show that this OD cuprate appears to have properties that approach that of the Mo. Further analysis shows that the OD has a more $k$-independent lineshape at the Fermi surface than the lower-doped cuprates. This allows for a realistic comparison of the nodal lifetime values to the experimental resistivity measurements via Boltzmann transport formulation. All these observations point to the validity of the quasiparticle picture for the OD even in the normal state within a certain energy and momentum range.Comment: 4 pages, 4 figure

Nature of the Electronic Excitations near the Brillouin Zone Boundary of Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}

Based on angle resolved photoemission spectra measured on different systems at different dopings, momenta and photon energies, we show that the anomalously large spectral linewidth in the $(\pi,0)$ region of optimal doped and underdoped Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ has significant contributions from the bilayer splitting, and that the scattering rate in this region is considerably smaller than previously estimated. This new picture of the electronic excitation near $(\pi,0)$ puts additional experimental constraints on various microscopic theories and data analysis.Comment: 5 pages, 4 figure