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1

Modeling Earth's Energy Balance  

Science.gov (United States)

In this activity, learners use the STELLA box modeling software to determine Earth's temperature based on incoming solar radiation and outgoing terrestrial radiation. Starting with a simple black body model, the exercise gradually adds complexity by incorporating albedo, then a 1-layer atmosphere, then a 2-layer atmosphere, and finally a complex atmosphere with latent and sensible heat fluxes. With each step, students compare the modeled surface temperature to Earth's actual surface temperature, thereby providing a check on how well each increasingly complex model captures the physics of the actual system.

Menking, Kirsten; College, Vassar; Science Education Resource Center, On T.

2

Dual shell pressure balanced vessel  

Science.gov (United States)

A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

3

Pressure balance at the magnetopause: Experimental studies  

CERN Document Server

The pressure balance at the magnetopause is formed by magnetic field and plasma in the magnetosheath, on one side, and inside the magnetosphere, on the other side. In the approach of dipole earth's magnetic field configuration and gas-dynamics solar wind flowing around the magnetosphere, the pressure balance predicts that the magnetopause distance R depends on solar wind dynamic pressure Pd as a power low R ~ Pd^alpha, where the exponent alpha=-1/6. In the real magnetosphere the magnetic filed is contributed by additional sources: Chapman-Ferraro current system, field-aligned currents, tail current, and storm-time ring current. Net contribution of those sources depends on particular magnetospheric region and varies with solar wind conditions and geomagnetic activity. As a result, the parameters of pressure balance, including power index alpha, depend on both the local position at the magnetopause and geomagnetic activity. In addition, the pressure balance can be affected by a non-linear transfer of the solar ...

Suvorova, A V

2011-01-01

4

Gallery Walk Questions on Earth's Radiation Balance  

Science.gov (United States)

created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about the Earth's Radiation Balance. The questions are organized ...

5

Rare earth luminescence under pressure  

International Nuclear Information System (INIS)

The luminescence properties of different rare earth ions (RE3+ : Sm3+, Tb3+ and Er3+) in lithium fluoroborate glasses and oxyfluoride nanocrystalline glass-ceramics have been analyzed as a function of the pressure. The roles of the pressure-induced energy transfer between optically active ions, their host local structures and the energy trap centers in the quenching of the rare earth luminescence are discussed

6

Sunspot geometry and pressure balance  

International Nuclear Information System (INIS)

Measurements on magnetic canopies extending from sunspots show that, at the outer penumbral edge, heights of the bases are independent of sunspot diameter and average 180 km. This places a lower limit on the outer penumbral base; with an assumed thickness of 250 km, the top is approx. equal to 430 km above z = 0(tausub(c) = 1) in the photosphere. Chistyakov's (1962) observations require the penumbral surface to be convex in radial section. The Wilson depression, able thus to be found only from limb-side penumbras, is 1360 km from his selected measurements. Averaged over all regular sunspots without special selection, this drops to 1040 km. Thus tausup(*) = 1 in umbras lies around z = -610 km. Magnetic field-strength measurements relate probably to tausup(*) approx. equal to 0.02, some 160 km higher, where z approx. equal to -450 km. The magnetic pressure of the typical 3250 G sunspot field would support the external-axial gas-pressure difference at z = -330 km, the difference of 120 km lying well within the uncertainties. Tension forces, commonly invoked to achieve pressure balance, do not exceed the uncertainties of measurement. Beyond the sunspot, the base of the sunspot field rises only slowly over at least 16000 km horizontally, whereas Beckers (1963) found the inclination of H? superpenumbral fibrils to be some 130. These results are nicely compatible since the field angle is typically of this magnitude at the minimum heights where H? fibrils will beminimum heights where H? fibrils will be observed, say 1400 km. (orig.)

7

Temperature, Pressure, and the Earth  

Science.gov (United States)

This is a lesson where learners explore the effects of pressure on temperature and states of matter and use this information to infer the conditions of the interior of the Earth. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 2 in the Astro-Venture Geology Training Unit that was developed to increase students' awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use with the Astro-Venture multimedia modules.

8

Pressure balance equilibria in the Rotamak  

International Nuclear Information System (INIS)

It is shown that the steady phase in the operation of the Rotamak is well described by the assumption that the plasma is in an averaged magnetohydrodynamic pressure balance situation and that, using a model based on this assumption, self-consistency imposes conditions relating the temperature and density of the plasma to the steady components of the internal magnetic fields

9

The energy balance of the earth' surface : a practical approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study is devoted to the energy balance of the earth's surface with a special emphasis on practical applications. A simple picture of the energy exchange processes that take place at the ground is the following. Per unit time and area an amount of radiant energy is supplied to the surface. This radiation originates partly from the sun, but an~ other fraction is coming from the atmosphere (= infra-red radiation emitted by clouds, water vapour and CO 2 ). F...

Bruin, H. A. R.

1982-01-01

10

Low-temperature hydrogen circulation system of the pressure balance  

International Nuclear Information System (INIS)

In China Spallation Neutron Source (CSNS), which is under construction recently in Southern China, a cryogenic system is used to cool down the neutron moderator. Pressure control system is a key unit to balance the pressure in H2 loop. Denisty of H2 in loop is almost constant under the design condition of 18-21K. When temperature change 1K, large variation pressure about 1 MPa change in H2 loop. By analysis three pressure control modes of warm buffer, cryogenic dewar and accumulator, pressure fluctuation can be controlled by accumulator more perfectly with less hydrogen inventory in H2 loop. (authors)

11

Application of satellite scatterometer to the study of Earth angular momentum balance  

Science.gov (United States)

The dynamics of the Earth system has been studied for many years; however, it is still not fully understood on a fundamental level because of its underlying complexity. The interactions among the atmosphere, ocean and solid Earth, which occur through energy and momentum exchanges and mass transport, are often essential. However, the actual mechanisms by which the angular momentum is transferred from the atmosphere to the solid Earth still remain unclear. The atmosphere exchanges angular momentum with the solid Earth through the two major torques: wind stress torque and mountain torque. The ocean exchanges angular momentum with the solid Earth through pressure and friction torque acting on the ocean floor. Since a large portion of the atmospheric angular momentum is exchanged with the ocean through the wind stress torque acting on the sea surface, precise observations of sea surface wind, the major driven force causing the oceanic circulation, can provide an opportunity for fully understanding these mechanisms. A quantitative understanding of the relations between the wind forcing and the reaction of the ocean is also desirable. In this research, the European Remote Sensing Satellite 1 (ERS-1) scatterometer measurements were reprocessed using the European Space Agency (ESA)'s CMOD4 model function and a line-wise ambiguity removal algorithm with sea-ice detection scheme to obtain the unique wind vector from the scatterometer's multi-solutions. The reprocessed wind stress fields were compared with both ESA's wind products and the National Center for Environmental Prediction (NCEP) analytical fields. The results indicated that the wind stress fields generated by the new algorithm are reasonably better. This more accurate and consistent ERS-1 scatterometer global high resolution surface wind data was then used to study the Earth system angular momentum balance, including forcing a parallel free-surface ocean general circulation model to investigate the changes of the oceanic angular momentum and its contribution to the Earth angular momentum balance. The calculated global torque agrees very well with changes in the atmospheric angular momentum. The oceanic angular momentum itself only accounts for a relatively small portion in the Earth angular momentum balance. Torques that include the ERS-1 scatterometer wind forcing over the ocean produce a better balance with the rate of change of global atmospheric angular momentum compared to those from the NCEP model system alone.

Xu, Jin

12

Steady convection keeps Earth's magnetic field in balance  

Science.gov (United States)

The onslaught of the solar wind on the Sun-facing side of Earth's magnetic field causes terrestrial magnetic field lines to break through magnetic reconnection. The persistent pressure of the solar wind pulls the field lines and the associated plasma around to the magnetotail on Earth's nightside, where magnetic reconnection occurs once again to form the plasma sheet region. This uneven distribution creates a pressure gradient that drives nightside plasma back toward the planet. The Earthward transport of this nightside magnetospheric plasma is known to occur in one of two ways: as a magnetic substorm or as steady magnetospheric convection (SMC). Substorms include acute inflows that cause plasma to pile up in the inner magnetosphere and have been tied to the onset of aurorae. SMC, on the other hand, has been proposed as a mechanism for rebalancing the plasma gradient established between the day and night sides of Earth's magnetic field. Kissinger et al. compiled 14 years of magnetic field and plasma observations to study how plasma flows and magnetospheric conditions differ between SMC events and substorms.

Schultz, Colin

2012-06-01

13

Earth in the balance. Ecology and the human spirit  

International Nuclear Information System (INIS)

This book is the translation of the original American edition ''earth in the balance''. When Earth in the Balance first came out, it caused quite a stir and for good reason. It convincingly makes the case that a crisis of epidemic proportions is nearly upon us and that if the world does not get its act together soon and agree to some kind of 'Global Marshall Plan' to protect the environment, we're all up a polluted creek without a paddle. Myriad plagues are upon us, but the worst include the loss of biodiversity, the depletion of the ozone layer, the slash-and-burn destruction of rain forests, and the onset of global warming. None of this is new, of course, nor was it new in 1992. But most environmentalists will still get a giddy feeling reading such a call to action as written by a prominent politician. The book is arranged into three sections: the first describes the plagues; the second looks at how we got ourselves into this mess; and the final chapters present ways out. Gore gets his points across in a serviceable way, though he could have benefited from a firmer editor's hand; at times the analogies are arcane and the pacing is odd kind of like a Gore speech that climaxes at weird points and then sinks just as the audience is about to clap. Still, at the end you understand what's been said. Gore believes that if we apply some American ingenuity, the twin engines of democracy and capitalism can be rigged to help us stabilize world population growth, spread social ze world population growth, spread social justice, boost education levels, create environmentally appropriate technologies, and negotiate international agreements to bring us back from the brink. For example, a worldwide shift to clean, renewable energy sources would create huge economic opportunities for companies large and small to design, build, and maintain solar panels, wind turbines, fuel cells, and other eco friendly innovations

14

Rigidly framed earth retaining structures thermal soil structure interaction of buildings supporting unbalanced lateral earth pressures  

CERN Document Server

Structures placed on hillsides often present a number of challenges and a limited number of economical choices for site design. An option sometimes employed is to use the building frame as a retaining element, comprising a Rigidly Framed Earth Retaining Structure (RFERS). The relationship between temperature and earth pressure acting on RFERS, is explored in this monograph through a 4.5 year monitoring program of a heavily instrumented in service structure. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also revealed that thermal cycles, rather than lateral earth pressure, were the cause of failure in many structural elements. The book demonstrates that depending on the relative stiffness of the retained soil mass and that of the structural frame, the developed lateral earth pressure, during thermal expansion, can reach magnitudes several times larger than those determined using classical earth pressure theories....

Aboumoussa, Walid

2014-01-01

15

Reliability of Center of Pressure Measures During Dynamic Balance Performance  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Aim: Few studies have assessed the reliability of postural balance measures during dynamic balance performance that introduce additional challenging to postural control system. In addition sometimes in the static conditions some deficiencies of the postural control system may not be revealed obviously therefore the aim of this study was to assess the reliability of postural control parameters during functional performance on force plate in healthy subjects.Materials and Methods: Ten healthy male subjects (mean age: 25.4 years, weight: 68.2 kg height:176.9cm participated in this study. None of the subjects were involved in sport activities. Every subject performed three 15seconds trials of eyes open single leg stance on a force plate during dynamic balance task. Participants grasped object with hand at their waist level and release it at above shoulder level. The reproducibility of the center of pressure (COP deviations (average speed &length of path was assessed. All participants were tested on 2 sessions with an inter-measurement interval of 7 days. COP data was collected for each trial. The intraclass correlation coefficient (ICC was used as parameter of intra-session and inter-session (Test-Retest reliability.Results: The ICCs for intra-session reliability of average speed and length of COP path were 0.89 and 0.91 respectively. The ICCs for inter-session reliability were 0.95 and 0.96 respectively.Conclusion: The study showed high and very high reliability for center of pressure measures during dynamic balance task. Therefore this dynamic performance can be used as a balance pattern in postural control assessment. These can be used as reliable parameters in dynamic postural control assessment due to high reliability of average speed and length of COP path.

Mohammad Ali Sanjary

2011-12-01

16

Physical Limitations of Empirical Field Models: Force Balance and Plasma Pressure  

International Nuclear Information System (INIS)

In this paper, we study whether the magnetic field of the T96 empirical model can be in force balance with an isotropic plasma pressure distribution. Using the field of T96, we obtain values for the pressure P by solving a Poisson-type equation (gradient)2P = (gradient) · (J x B) in the equatorial plane, and 1-D profiles on the Sun-Earth axis by integrating (gradient)P = J x B. We work in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials. Our results lead to the conclusion that the T96 model field cannot be in equilibrium with an isotropic pressure. We also analyze in detail the computation of Birkeland currents using the Vasyliunas relation and the T96 field, which yields unphysical results, again indicating the lack of force balance in the empirical model. The underlying reason for the force imbalance is likely the fact that the derivatives of the least-square fitted model B are not accurate predictions of the actual magnetospheric field derivatives. Finally, we discuss a possible solution to the problem of lack of force balance in empirical field models

17

Physical Limitations of Empirical Field Models: Force Balance and Plasma Pressure  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we study whether the magnetic field of the T96 empirical model can be in force balance with an isotropic plasma pressure distribution. Using the field of T96, we obtain values for the pressure P by solving a Poisson-type equation {del}{sup 2}P = {del} {center_dot} (J x B) in the equatorial plane, and 1-D profiles on the Sun-Earth axis by integrating {del}P = J x B. We work in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials. Our results lead to the conclusion that the T96 model field cannot be in equilibrium with an isotropic pressure. We also analyze in detail the computation of Birkeland currents using the Vasyliunas relation and the T96 field, which yields unphysical results, again indicating the lack of force balance in the empirical model. The underlying reason for the force imbalance is likely the fact that the derivatives of the least-square fitted model B are not accurate predictions of the actual magnetospheric field derivatives. Finally, we discuss a possible solution to the problem of lack of force balance in empirical field models.

Sorin Zaharia; C.Z. Cheng

2002-06-18

18

Dual shell pressure balanced reactor vessel. Final project report  

International Nuclear Information System (INIS)

The Department of Energy's Office of Energy Research (OER) has previously provided support for the development of several chemical processes, including supercritical water oxidation, liquefaction, and aqueous hazardous waste destruction, where chemical and phase transformations are conducted at high pressure and temperature. These and many other commercial processes require a pressure vessel capable of operating in a corrosive environment where safety and economy are important requirements. Pacific Northwest Laboratory (PNL) engineers have recently developed and patented (U.S. patent 5,167,930 December 1, 1992) a concept for a novel Dual Shell Pressure Balanced Vessel (DSPBV) which could solve a number of these problems. The technology could be immediately useful in continuing commercialization of an R ampersand D 100 award-winning technology, Sludge-to-oil Reactor System (STORS), originally developed through funding by OER. Innotek Corporation is a small business that would be one logical end-user of the DSPBV reactor technology. Innotek is working with several major U.S. engineering firms to evaluate the potential of this technology in the disposal of wastes from sewage treatment plants. PNL entered into a CRADA with Innotek to build a bench-scale demonstration reactor and test the system to advance the economic feasibility of a variety of high pressure chemical processes. Hydrothermal processing of corrosive substances on a large scale can now be made significantly safer and more economical through use of the DSPBV. Hydrothermal chemical reactions such as wet-air oxidation and supercritical water oxidation occur in a highly corrosive environment inside a pressure vessel. Average corrosion rates from 23 to 80 miles per year have been reported by Rice (1994) and Latanision (1993)

19

Changes in Earth's radiation balance between 1985 and 2012  

Science.gov (United States)

Since the turn of the century, surface temperatures on Earth have continued to increase, but at a slower rate than between 1985 and 1999. This is despite increasing greenhouse gas emissions due to human activity. Consistent with the steadily increasing strength of the greenhouse effect, Allan et al. find that heating of the planet—measured as the difference between the amount of sunlight absorbed by Earth and the longwave radiative energy emitted to space—was greater between 2000 and 2012 than during the earlier time period, 1985-1999, despite the slowing rate of surface warming.

Orwig, Jessica

2014-11-01

20

Elastic properties of alkaline earth oxides under high pressure  

International Nuclear Information System (INIS)

A phenomenological theory has been developed to describe the elastic behavior of alkaline earth oxide solids under high pressure. The values of second order elastic constants, Cauchy's deviation and Zener anisotropy ratio at different pressures have been computed for MgO, CaO, SrO, and BaO. The results were found to be satisfactory and in agreement with available experimental and other theoretical results

 
 
 
 
21

Progress in development of controlled-clearance pressure balance in NMIJ  

International Nuclear Information System (INIS)

A new controlled-clearance pressure balance is under development with the aim of improving the hydraulic high-pressure standard up to 1 GPa. This pressure balance consists of three parts: (i) a pressure generation device up to 1 GPa, (ii) a weight-loading unit which can load/unload weights automatically and independently, (iii) a controlled-clearance piston-cylinder which is designed to allow the jacket pressure to be applied independently. Some adjustments were made for loading heavy weights on/off the piston safely, keeping them in balance, then generating the pressure stably. Stability of the generated pressure was checked for several piston-cylinders, and it was found that pressure fluctuation was less than a few parts per million. The jacket pressure coefficient of a 500 MPa controlled-clearance piston-cylinder was precisely evaluated as a function of both the system pressure and the jacket pressure.

22

EDITORIAL: The Earth radiation balance as driver of the global hydrological cycle  

Science.gov (United States)

Variations in the intensity of the global hydrological cycle can have far-reaching effects on living conditions on our planet. While climate change discussions often revolve around possible consequences of future temperature changes, the adaptation to changes in the hydrological cycle may pose a bigger challenge to societies and ecosystems. Floods and droughts are already today amongst the most damaging natural hazards, with floods being globally the most significant disaster type in terms of loss of human life (Jonkman 2005). From an economic perspective, changes in the hydrological cycle can impose great pressures and damages on a variety of industrial sectors, such as water management, urban planning, agricultural production and tourism. Despite their obvious environmental and societal importance, our understanding of the causes and magnitude of the variations of the hydrological cycle is still unsatisfactory (e.g., Ramanathan et al 2001, Ohmura and Wild 2002, Allen and Ingram 2002, Allan 2007, Wild et al 2008, Liepert and Previdi 2009). The link between radiation balance and hydrological cycle Globally, precipitation can be approximated by surface evaporation, since the variability of the atmospheric moisture storage is negligible. This is the case because the fluxes are an order of magnitude larger than the atmospheric storage (423 x 1012 m3 year-1 versus 13 x 1012 m3 according to Baumgartner and Reichel (1975)), the latter being determined by temperature (Clausius-Clapeyron). Hence the residence time of evaporated water in the atmosphere is not more than a few days, before it condenses and falls back to Earth in the form of precipitation. Any change in the globally averaged surface evaporation therefore implies an equivalent change in precipitation, and thus in the intensity of the global hydrological cycle. The process of evaporation requires energy, which it obtains from the surface radiation balance (also known as surface net radiation), composed of the absorbed solar and net thermal radiative exchanges at the Earth's surface. Globally averaged, this surface radiation balance is positive, since radiative absorption, scattering and emission in the climate system act to generate an energy surplus at the surface and an energy deficit in the atmosphere (Liepert 2010). Evaporation, or more precisely its energy equivalent, the latent heat flux, is the main process that compensates for this imbalance between surface and atmosphere, since the latent heat dominates the convective energy flux over sensible heating. The radiative energy surplus at the surface is thus mainly consumed by evaporation and moist convection and subsequently released in the atmosphere through condensation. This implies that any alterations in the available radiative energy will induce changes in the water fluxes. Our focus in this editorial is therefore on the surface radiation balance as the principal driver of the global hydrological cycle. Note that this energetic view is in agreement with that of Richter and Xie (2008) who argue that the spatial and temporal behaviour of the process of evaporation is controlled by surface and atmospheric properties such as atmospheric stability, wind speed, moisture deficit and moisture availability. From radiation theory it is expected that with increasing radiative absorption due to abundance of anthropogenic greenhouse gases in the atmosphere and consequent warming, the emission of thermal energy from the atmosphere towards the surface is increasing (known as downward thermal radiation). This enhances the radiative energy surplus at the surface, and, where surface water is not limited, fuels evaporation besides warming the Earth's surface. The enhanced greenhouse effect therefore tends to accelerate the hydrological cycle, as also shown in many climate model simulations with increasing levels of greenhouse gases (e.g., IPCC 2007, but also see Yang et al 2003, Andrews et al 2009). We can assume that the increase in greenhouse gases since preindustrial times had already led to a substantial increase of downw

Wild, Martin; Liepert, Beate

2010-06-01

23

Pressure-temperature Phase Diagram of the Earth  

CERN Document Server

Based on a pressure-temperature (P-T) phase diagram model of the Earth, Jones & Lineweaver (2010) described uninhabited terrestrial liquid water. Our model represents the atmosphere, surface, oceans and interior of the Earth - allowing the range of P-T conditions in terrestrial environments to be compared to the phase regime of liquid water. Here we present an overview and additional results from the Earth model on the location of the deepest liquid water on Earth and the maximum possible extent of the terrestrial biosphere. The intersection of liquid water and terrestrial phase space indicates that the deepest liquid water environments in the lithosphere occur at a depth of ~ 75 km. 3.5 % of the volume of the Earth is above 75 km depth. Considering the 3.5 % of the volume of the Earth where liquid water exists, ~ 12% of this volume is inhabited by life while the remaining ~ 88% is uninhabited. This is distinct from the fraction of the volume of liquid water occupied by life. We find that at least 1% of t...

Jones, Eriita

2010-01-01

24

STOCHASTIC ACCELERATION OF SUPRATHERMAL PARTICLES UNDER PRESSURE BALANCE CONDITIONS  

Energy Technology Data Exchange (ETDEWEB)

The acceleration of suprathermal charged particles in the heliosphere under pressure balance conditions including for the first time the radial spatial particle diffusion and convection in the solar wind is investigated. The physical conditions are derived for which the stationary phase space distribution of suprathermal particles approaches the power-law distribution f{proportional_to}p {sup -5}, which is often seen in spacecraft observations. For separable source distributions in momentum and position we analytically solve the stationary particle transport equation for a radially constant solar wind speed V {sub 0} and a momentum-independent radial spatial diffusion coefficient. The resulting stationary solution at any position within the finite heliosphere is the superposition of an infinite sum of power laws in momentum below and above the (assumed mono-momentum) injection momentum p{sub I} . The smallest spatial eigenvalue determines the flattest power law, to which the full stationary solution approaches at large and small enough momenta. Only for the case of a reflecting inner and a free-escape outer spatial boundary, does one small eigenvalue exist, yielding the power-law distribution f{proportional_to}p {sup -5} at sufficiently large momentum values. The other three spatial boundary conditions imply steeper momentum spectra. Momentum spectra and radial profiles of suprathermal particles are calculated by adopting a uniform outer ring spatial source distribution.

Antecki, T.; Schlickeiser, R. [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Zhang, M., E-mail: ta@tp4.rub.de, E-mail: rsch@tp4.rub.de, E-mail: mzhang@fit.edu [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

2013-02-10

25

Earth in the balance - ecology and the human spirit  

International Nuclear Information System (INIS)

This book by Senator Albert Gore presents a global prospective on the environmental crisis facing the Earth. The chapters are framed in the twin ideas of the threat posed by human civilization to the global environment and the threat to human civilization posed by changes in the global environment. Gore first looks at evidence of risk in the environment: historical aspects of climate and civilization; ozone layer; water; land use; food supply; waste disposal. In Part II different aspects of our current approaches to the environment are described: politics; economics; technology; social problems; environmentalism of the human spirit. Finally in Part III, Gore presents his approach to the global environmental crisis, first presenting a section about a global sense of responsibility and purpose and then describing his ideas for A Global Marshal Plan. 169 refs., 4 figs

26

Anomalous high pressure behaviour in nanosized rare earth sesquioxides  

Science.gov (United States)

We report Raman spectroscopic studies of the nanosized rare earth sesquioxides, namely yttrium sesquioxide (Y2O3), gadolinium sesquioxide (Gd2O3) and samarium sesquioxide (Sm2O3), under high pressure. The samples were characterized using x-ray diffraction, Raman spectroscopy and atomic force microscopy at atmospheric pressures. Y2O3 and Gd2O3 were found to be cubic at ambient, while Sm2O3 was found to be predominantly cubic with a small fraction of monoclinic phase. The strongest Raman peaks are observed at 379, 344 and 363 cm-1, respectively, for Y2O3, Sm2O3 and Gd2O3. All the samples were found to be nanosized with 50-90 nm particle sizes. The high pressures were generated using a Mao-Bell type diamond anvil cell and a conventional laser Raman spectrometer is used to monitor the pressure-induced changes. Y2O3 seems to undergo a crystalline to partial amorphous transition when pressurized up to about 19 GPa, with traces of hexagonal phase. However, on release of pressure, the hexagonal phase develops into the dominant phase. Gd2O3 is also seen to develop into a mixture of amorphous and hexagonal phases on pressurizing. However, on release of pressure Gd2O3 does not show any change and the transformation is found to be irreversible. On the other hand, Sm2O3 shows a weakening of cubic phase peaks while monoclinic phase peaks gain intensity up to about a pressure of 6.79 GPa. However, thereafter the monoclinic phase peaks also reduce in intensity and mostly disordering sets in which does not show significant reversal as the pressure is released. The results obtained are discussed in detail.

Dilawar, Nita; Varandani, Deepak; Mehrotra, Shalini; Poswal, Himanshu K.; Sharma, Surinder M.; Bandyopadhyay, Ashis K.

2008-03-01

27

High Pressure Behavior of Organic Materials and the Early Earth  

Science.gov (United States)

Organic molecules observed in proto-planetary discs, such as cyanuric acid (H3C3N3O3), transform through currently unknown processes to the complex prebiotic compounds believed to have led to life on Earth. These processes could occur within the upper layers of the early Earth during the Hadean and Archaean. Laboratory experiments show that pressures of 1-10 GPa and temperatures of 300-600 K facilitate the formation of complex molecules from simple organic precursors. In particular, formic acid, another organic material associated with proto-planetary discs, undergoes irreversible reactions at pressures and temperatures above 2.5 GPa and 430 K with the products characterized by Raman peaks at 1349, 1520 and 1592 cm^{- 1}, close to peaks measured from interplanetary dust particle material. Cyanuric acid is of special interest because it has a structure similar to the carbon-nitrogen rings and helices incorporated in nucleosides and other key biological components. It appears to form N-H\\dotsO and C--O\\dotsH intramolecular bonds at pressures above 5.0 GPa, and forms complex macromolecular material at temperatures over 400K. If by emerging below the surface of a planet it can be protected from impact (including the late heavy bombardment) and other external threats, life may ultimately be initiated by conformational changes induced in pre-biotic molecules by pressure.

Montgomery, W.; Crowhurst, J.; Zaug, J. M.; Jeanloz, R.

2006-12-01

28

Phase transitions in rare earth tellurides under pressure  

Science.gov (United States)

Using first-principles calculations we have studied the valence and structural transitions of the rare earth monotellurides RTe (R = Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) under pressure. The self-interaction corrected local spin-density approximation is used to establish the ground state valence configuration as a function of volume for the RTe in both the NaCl (B1) and CsCl (B2) structures. We find that in ambient conditions all the RTe are stabilized in the B1 structure. A trivalent (R3+) rare earth ground state is predicted for the majority of the RTe, with the exception of SmTe, EuTe, DyTe, TmTe and YbTe, where the fully localized divalent (R2+) rare earth configuration is found to be energetically most favourable. Under pressure, the trivalent RTe undergo structural transitions to the B2 structure without associated valence transition. The divalent RTe on the other hand are characterized by a competition between the structural and electronic degrees of freedom, and it is the degree of f-electron delocalization that determines the sequence of phase transitions. In EuTe and YbTe, where respectively the half-filled and filled shells result in a very stable divalent configuration, we find that it is the structural B1 ? B2 transition that occurs first, followed by the R2+ ? R3+ valence transition at even higher pressures. In SmTe, DyTe and TmTe, the electronic transition occurs prior to the structural transition. With the exception of YbTe, the calculated transition pressures are found to be in good agreement with experiment.

Petit, L.; Svane, A.; Lüders, M.; Szotek, Z.; Vaitheeswaran, G.; Kanchana, V.; Temmerman, W. M.

2014-07-01

29

High Pressure Structural Studies on Rare-Earth Sesquioxides  

Science.gov (United States)

The Rare-Earth sesquioxides (RE2O3) exhibit interesting physical and chemical properties. Some of these oxides have tremendous technological applications. At ambient conditions, the RE2O3 systems exist in three polymorphic forms, namely: hexagonal A- type, monoclinic B- type, and cubic C- type. The structural stability of three RE2O3 systems: RE = Gd, Ho, Tm and the Tb4O7 system have been studied under high pressure. All the four systems exhibited interesting pressure induced phase transitions. Gd2O3 exhibited C-A transition at ~ 12 GPa, whereas Ho2O3 and Tm2O3 exhibited C-B transition at pressures of 9.5 and 7 GPa respectively. Tb4O7 transformed from its cubic fluorite structure to probably the cotunnite phase at a relatively higher pressure of 27 GPa. The unusual large pressure stability of Tb4O7 was attributed to the presence of Tb4+ ions. The bulk moduli show systematic increase with higher cations, probably due to the enhanced influence of the 4f electron states and increased nature of covalency. However, the mechanisms of the structural transitions C-B-A with increased pressure and increased cation radii are yet to be understood.

Sahu, P. Ch; Lonappan, Dayana; Shekar, N. V. Chandra

2012-07-01

30

The effect of cloud type on Earth's energy balance - Global analysis  

Science.gov (United States)

The role of fractional area coverage by cloud types in the energy balance of the earth is investigated through joint use of International Satellite Cloud Climatology Project (ISCCP) C1 cloud data and Earth Radiation Budget Experiment (ERBE) broadband energy flux data for the one-year period March 1985 through February 1986. Multiple linear regression is used to relate the radiation budget data to the cloud data. Comparing cloud forcing estimates obtained from the ISCCP-ERBE regression with those derived from the ERBE scene identification shows generally good agreement except over snow, in tropical convective regions, and in regions that are either nearly cloudless or always overcast. It is suggested that a substantial fraction of the disagreement in longwave cloud forcing in tropical convective regions is associated with the fact that the ERBE scene identification does not take into account variations in upper-tropospheric water vapor. On a global average basis, low clouds make the largest contribution to the net energy balance of the Earth, because they cover such a large area and because their albedo effect dominates their effect on emitted thermal radiation. High, optically thick clouds can also very effectively reduce the energy balance, however, because their very high albedos overcome their low emission temperatures.

Hartmann, Dennis L.; Ockert-Bell, Maureen E.; Michelsen, Marc L.

1992-01-01

31

THE HABITABLE ZONE OF EARTH-LIKE PLANETS WITH DIFFERENT LEVELS OF ATMOSPHERIC PRESSURE  

Energy Technology Data Exchange (ETDEWEB)

As a contribution to the study of the habitability of extrasolar planets, we implemented a one-dimensional energy balance model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p = 1/3 to 3 bar. At low pressure, the habitability is low and varies with a; at high pressure, the habitability is high and relatively constant inside the HZ. We interpret these results in terms of the pressure dependence of the greenhouse effect, the efficiency of horizontal heat transport, and the extent of the liquid water temperature range. Within the limits discussed in the paper, the results can be extended to planets in eccentric orbits around non-solar-type stars. The main characteristics of the pressure-dependent HZ are modestly affected by variations of planetary properties, particularly at high pressure.

Vladilo, Giovanni; Murante, Giuseppe; Silva, Laura [INAF-Trieste Astronomical Observatory, Trieste (Italy); Provenzale, Antonello [Institute of Atmospheric Sciences and Climate-CNR, Torino (Italy); Ferri, Gaia; Ragazzini, Gregorio, E-mail: vladilo@oats.inaf.it [Department of Physics, University of Trieste, Trieste (Italy)

2013-04-10

32

THE HABITABLE ZONE OF EARTH-LIKE PLANETS WITH DIFFERENT LEVELS OF ATMOSPHERIC PRESSURE  

International Nuclear Information System (INIS)

As a contribution to the study of the habitability of extrasolar planets, we implemented a one-dimensional energy balance model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p = 1/3 to 3 bar. At low pressure, the habitability is low and varies with a; at high pressure, the habitability is high and relatively constant inside the HZ. We interpret these results in terms of the pressure dependence of the greenhouse effect, the efficiency of horizontal heat transport, and the extent of the liquid water temperature range. Within the limits discussed in the paper, the results can be extended to planets in eccentric orbits around non-solar-type stars. The main characteristics of the prestars. The main characteristics of the pressure-dependent HZ are modestly affected by variations of planetary properties, particularly at high pressure.

33

The habitable zone of Earth-like planets with different levels of atmospheric pressure  

CERN Document Server

As a contribution to the study of the habitability of extrasolar planets, we implemented a 1-D Energy Balance Model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p=1/3 bar to p=3 bar. At low pressure, the habitability is...

Vladilo, Giovanni; Silva, Laura; Provenzale, Antonello; Ferri, Gaia; Ragazzini, Gregorio

2013-01-01

34

High pressure behaviour of heavy rare earth antimonides  

International Nuclear Information System (INIS)

We have investigated theoretically the high-pressure structural phase transition and cohesive properties of two heavy rare earth mono anyimonides (LnSb; Ln = Dy and Lu) by using two body interionic potential with necessary modifications to include the effect of Coulomb screening by the delocalized 4f electrons of the RE ion. The peculiar properties of these compounds have been interpreted in terms of the hybridization of f electrons with the conduction band. The calculated compression curves and the values of high-pressure behaviour have been discussed and compared with the experimental results. These compounds exhibits first order crystallographic phase transition from their NaCl (B1) phase to CsCl (B2) phase at 23.6 GPa and 25.4 GPa respectively. At phase transition the % volume collapse for both the compounds are little higher than the measured ones. The NaCl phase possesses lower energy than CsCl phase and stable at ambient pressure. The bulk moduli of LnSb compounds are obtained from the P-V curve fitted by the Birch equation of state. We also calculated the Ln-Ln distance as a function of pressure. (author)

35

Balancing the books – a statistical theory of prospective budgets in Earth System science  

Directory of Open Access Journals (Sweden)

Full Text Available An honest declaration of the error in a mass, momentum or energy balance, ?, simply raises the question of its acceptability: 'At what value of ? is the attempted balance to be rejected?' Answering this question requires a reference quantity against which to compare ?. This quantity must be a mathematical function of all the data used in making the balance. To deliver this function, a theory grounded in a workable definition of acceptability is essential. A distinction must be drawn between a retrospective balance and a prospective budget in relation to any natural space-filling body. Balances look to the past; budgets look to the future. The theory is built on the application of classical sampling theory to the measurement and closure of a prospective budget. It satisfies R.A. Fisher's 'vital requirement that the actual and physical conduct of experiments should govern the statistical procedure of their interpretation'. It provides a test, which rejects, or fails to reject, the hypothesis that the closing error on the budget, when realised, was due to sampling error only. By increasing the number of measurements, the discrimination of the test can be improved, controlling both the precision and accuracy of the budget and its components. The cost-effective design of such measurement campaigns is discussed briefly. This analysis may also show when campaigns to close a budget on a particular space-filling body are not worth the effort for either scientific or economic reasons. Other approaches, such as those based on stochastic processes, lack this finality, because they fail to distinguish between different types of error in the mismatch between a set of realisations of the process and the measured data. Keywords: balance, budget, sampling, hypothesis test, closing error, Earth System

J. P. O'Kane

2003-01-01

36

Balancing food and predator pressure induces chronic stress in songbirds.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The never-ending tension between finding food and avoiding predators may be the most universal natural stressor wild animals experience. The 'chronic stress' hypothesis predicts: (i) an animal's stress profile will be a simultaneous function of food and predator pressures given the aforesaid tension; and (ii) these inseparable effects on physiology will produce inseparable effects on demography because of the resulting adverse health effects. This hypothesis was originally proposed to explain...

Clinchy, Michael; Zanette, Liana; Boonstra, Rudy; Wingfield, John C.; Smith, James N. M.

2004-01-01

37

Effect of pumping methods on transmembrane pressure, fluid balance and relative recovery in microdialysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is a growing interest in using large pore size probes for microdialysis of macromolecular markers to monitor cell and tissue functions. Fluid balance could be an important issue when using large pore size microdialysis probes, which are affected by the mode of operation. In this study, the effect of pumping systems, push, pull, push-and-pull, and the resulting transmembrane pressure on the fluid balance, as well as, the relative recovery of small molecular nutrients and metabolites and ...

Li, Z.; Hughes, D.; Urban, Jpg; Cui, Z.

2008-01-01

38

SEX DIFFERENCES IN SYMPATHETIC NEURAL-HEMODYNAMIC BALANCE: IMPLICATIONS FOR HUMAN BLOOD PRESSURE REGULATION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Among young normotensive men a reciprocal balance between cardiac output and sympathetic nerve activity is important in the regulation of arterial pressure. In young women, the balance among cardiac output, peripheral resistance and sympathetic nerve activity is unknown. Consequently, the aim of this study was to examine the relationship of cardiac output and total peripheral resistance to muscle sympathetic nerve activity in young women. Multi-unit peroneal recordings of muscle sympathetic n...

Hart, Emma C.; Charkoudian, Nisha; Wallin, B. Gunnar; Curry, Timothy B.; Eisenach, John H.; Joyner, Michael J.

2009-01-01

39

Contact and pressure balance structures in two-fluid cosmic-ray hydrodynamics  

Science.gov (United States)

The role of cosmic-ray-modified contact discontinuities and pressure balance structures in two-fluid cosmic-ray hydrodynamics in one Cartesian space dimension are investigated by means of analytic and numerical solution examples, as well as by weakly nonlinear asymptotics. The fundamental wave modes of the two-fluid cosmic-ray hydrodynamic equations in the long-wavelength limit consist of the backward and forward propagating cosmic-ray-modified sound waves, with sound speed dependent on both the cosmic-ray and thermal gas pressures; the contact discontinuity; and a pressure balance mode in which the sum ofthe cosmic ray and thermal gas pressure perturbations is zero. The pressure balance mode, like the contact discontinuity is advected with the background flow. The interaction of the pressure balance mode with the contact discontinuity is investigated by means of the method of multiple scales. The thermal gas and cosmic-ray pressure perturbations satisfy a linear diffusion equation, and entropy perturbations arising from nonisentropic initial conditions for the thermal gas are frozen into the fluid. The contact discontinuity and pressure balance eigenmodes both admit nonzero perturbations in the thermal gas, whereas the cosmic-ray-modified sound waves are isentropic. The total entropy perturbation is shared between the contact discontinuity and pressure balance eigenmodes, and examples are given in which there is a transfer of entropy between the two modes. In particular, N-wave type density disturbances are obtained which arise as a result of the entropy transfer between the two modes. A weakly nonlinear geometric optics perturbation expansion is used to study the long timescale evolution of the short-wavelength entropy wave and the thermal gas sound waves in a slowly varying, large-scale background flow. The weakly nonlinear geometric optics expansion is also used to generalize previous studies of squeezing instability for short-wavelength sound waves in the two fluid model, by including a weakly nonlinear wave steepening term that leads to shock formation, as well as the effect of long time and space dependence of the background flow. Implications of cosmic-ray-modified pressure balance structures and contact discontinuities in models of the interaction of traveling interplanetary shocks and compression and rarefraction waves with the solar wind termination shock are briefly discussed.

Webb, G. M.; Brio, M.; Zank, G. P.; Story, T.

1995-01-01

40

Seismic Earth Pressure Development in Sheet Pile Retaining Walls: A Numerical Study  

CERN Document Server

The design of retaining walls requires the complete knowledge of the earth pressure distribution behind the wall. Due to the complex soil-structure effect, the estimation of earth pressure is not an easy task; even in the static case. The problem becomes even more complex for the dynamic (i.e., seismic) analysis and design of retaining walls. Several earth pressure models have been developed over the years to integrate the dynamic earth pressure with the static earth pressure and to improve the design of retaining wall in seismic regions. Among all the models, MononobeOkabe (M-O) method is commonly used to estimate the magnitude of seismic earth pressures in retaining walls and is adopted in design practices around the world (e.g., EuroCode and Australian Standards). However, the M-O method has several drawbacks and does not provide reliable estimate of the earth pressure in many instances. This study investigates the accuracy of the M-O method to predict the dynamic earth pressure in sheet pile wall. A 2D pl...

Rajeev, P; Sivakugan, N

2015-01-01

 
 
 
 
41

Pressure Balance between Thermal and Non-Thermal Plasmas in the 3C129 Cluster  

CERN Document Server

With new Chandra observations of the cluster containing the two radio galaxies 3C129 and 3C129.1, we have made a fit to the X-ray surface brightness to obtain thermal pressures. VLA data at 1.4 GHz have been obtained to complement previous maps at 0.33 GHz and at 5 and 8 GHz. From these radio data, we are able to derive the minimum non-thermal pressure of various emitting volumes along the tail of 3C129 and in the lobes of 3C129.1. Under the assumption that the non-thermal plasma excludes significant thermal plasma, we may expect pressure balance for most features since ram pressure should be important only close to the cores of the galaxies. Since we find that the minimum non-thermal pressures are generally only a factor of a few below estimates of the ambient thermal pressure, we conclude that it is unlikely that relativistic protons contribute significantly to the total pressure. Reasonable contributions from low energy electrons and filling factors in the range 0.1 to 1 suffice to achieve pressure balance...

Harris, D E

2003-01-01

42

Three-dimensional axisymmetric magnetosphere in pressure balance with the solar wind  

International Nuclear Information System (INIS)

A computer model of a magnetosphere in which the magnetic dipole axis points into the solar wind has been developed. The axial symmetry implied by this physical situation admits a two-dimensional treatment. The model features (1) a magnetopause in pressure balance with the solar wind, (2) an analytic asymptotic tail model to account for the distant magnetotail, and (3) a full accounting of the magnetohydrodynamic pressure in the magnetosphere. The plasma pressure is a function of the Euler potential, ?( = rA/sub phi/). The principal physical result is that with an increase in the plasma pressure from zero the magnetic field configuration changes slowly at first. As the pressure increases further, the field configuration changes more rapidly until X and O lines are formed

43

Experimental study on the instability of Pressure Balance Injection System (PBIS)  

Energy Technology Data Exchange (ETDEWEB)

The Passive Safety Reactor has been developed to reduce the construction cost and to improve the safety. Japan Atomic Energy Research institute (JAERI) proposed the System-Integrated Pressurized Water Reactor (SPWR) as a Passive Safety Reactor. In the SPWR design, the Pressure Balanced Injection System (PBIS) was introduced for the passive safety concept. The water with boron in a containment vessel were passively injected into the core by the pressure difference between the containment vessel and reactor vessel at a severe accidental condition. However there are few studies on the thermo-hydraulic characteristics of the PBIS. In this study, the thermal hydraulics of the PBIS are experimentally investigated using the small scale model. The instability of the injected flow was observed in the adiabatic experiment. The instability was caused by the pressure balance between the two vessels. The mechanism of the instability are discussed, resulting in the good agreement with the experimental results. In the steam experiment, another instability was observed, which was caused by the heat balance in the main tank.

Okamoto, Koji; Teshima, Hideyuki; Madarame, Haruki [Univ. of Tokyo, Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-06-01

44

Experimental study on the instability of Pressure Balance Injection System (PBIS)  

International Nuclear Information System (INIS)

The Passive Safety Reactor has been developed to reduce the construction cost and to improve the safety. Japan Atomic Energy Research institute (JAERI) proposed the System-Integrated Pressurized Water Reactor (SPWR) as a Passive Safety Reactor. In the SPWR design, the Pressure Balanced Injection System (PBIS) was introduced for the passive safety concept. The water with boron in a containment vessel were passively injected into the core by the pressure difference between the containment vessel and reactor vessel at a severe accidental condition. However there are few studies on the thermo-hydraulic characteristics of the PBIS. In this study, the thermal hydraulics of the PBIS are experimentally investigated using the small scale model. The instability of the injected flow was observed in the adiabatic experiment. The instability was caused by the pressure balance between the two vessels. The mechanism of the instability are discussed, resulting in the good agreement with the experimental results. In the steam experiment, another instability was observed, which was caused by the heat balance in the main tank

45

Static and seismic passive earth pressure coefficients on rigid retaining structures: discussion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The author needs to be commended for his computational efforts in determining the passive earth pressure coefficients for both the static case as well as in the presence of pseudostatic earthquake forces. The upper bound theorem of limit analysis with the use of a kinematically admissible translational failure mechanism was formed as the basis for solving the problem. In this discussion, the passive earth pressure coefficients given by the author have been compared with those obtained on the ...

Kumar, Jyant

2001-01-01

46

Effect of balanced low pressure drying of curcuma longa leaf on skin immune activation activities.  

Science.gov (United States)

The effect of balanced low pressure drying pretreatment associated with ultrasonication extraction (BU) on the enhancement of skin immune modulatory activities of Curcuma longa leaf was studied by comparing with conventional hot air drying (HE), freeze drying (FE) and balanced low pressure drying (BE) pretreatment processes. In considering skin immune activation activities such as the inhibition of hyaluronidase activity, the BU extract showed ca. 10% higher than those of HE, and even higher than that of the FE extract. Nitric oxide production from macrophage of the BU extract in adding 1.0 mg/mL was increased up to 16.5 ?M. When measuring inhibition of IL-6 and TNF-a production from the human T lymphocytes (T cell), the BU extract also showed 53% and 78% of inhibition effect, respectively. It is found that the BU extract could effectively suppress the expression levels of skin inflammation related genes such as Cox-2 and iNOS, down to 80% and 85% compared to the control, respectively. Balanced low pressure drying process was especially active on dehydration of the leaves with minimizing the destruction and making easier elution of the bioactive substances, which resulted in higher extraction yield and better biological activities. PMID:25226899

Choi, Wooseok; Lim, Hye Won; Lee, Hyeon Yong

2014-01-01

47

Earth radiation balance as observed and represented in CMIP5 models  

Science.gov (United States)

The genesis and evolution of Earth's climate is largely regulated by the Earth radiation balance. Despite of its key role in the context of climate change, substantial uncertainties still exist in the quantification of the magnitudes of its different components, and its representation in climate models. While the net radiative energy flows in and out of the climate system at the top of atmosphere are now known with considerable accuracy from new satellite programs such as CERES and SORCE, the energy distribution within the climate system and at the Earth's surface is less well determined. Accordingly, the magnitudes of the components of the surface energy balance have recently been controversially disputed, and potential inconsistencies between the estimated magnitudes of the global energy and water cycle have been emphasized. Here we summarize this discussion as presented in Chapter 2.3 of the 5th IPCC assessment report (AR5). In this context we made an attempt to better constrain the magnitudes of the surface radiative components with largest uncertainties. In addition to satellite observations, we thereby made extensive use of the growing number of surface observations to constrain the radiation balance not only from space, but also from the surface. We combined these observations with the latest modeling efforts performed for AR5 (CMIP5) to infer best estimates for the global mean surface radiative components. Our analyses favor global mean values of downward surface solar and thermal radiation near 185 and 342 Wm-2, respectively, which are most compatible with surface observations (Wild et al. 2013). These estimates are on the order of 10 Wm-2 lower and higher, respectively, than in some of the previous global energy balance assessments, including those presented in previous IPCC reports. It is encouraging that these estimates, which make full use of the information contained in the surface networks, coincide within 2 Wm-2 with the latest satellite-derived estimates (Kato et al. 2013), which are completely independently determined. This enhances confidence in these recent surface flux estimates. IPCC AR5 further presents increasing evidence from direct observations that the surface radiative fluxes undergo significant changes on decadal timescales, not only in their thermal components as expected from the increasing greenhouse effect, but also in the amount of solar radiation that reaches the Earth surface. In the thermal range, surface observations suggest an overall increase of downward thermal radiation in line with latest projections from the CMIP5 models and expectations from an increasing greenhouse effect. On the other hand the strong decadal changes in surface solar radiation seen in the observations ("dimming/brightening") are not fully captured by current climate models. These decadal changes in surface solar radiation may largely affect various aspects of climate change. Selected related references: Hartmann, D.L., A.M.G. Klein Tank, M. Rusticucci, L. Alexander, S. Brönnimann, Y. Charabi, F. Dentener, E. Dlugokencky, D. Easterling, A. Kaplan, B. Soden, P. Thorne, M. Wild and P.M. Zhai, 2013: Observations: Atmosphere and Surface. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kato, S., Loeb, N.G., Rose, F.G., Doelling, D.R., Rutan, D.A., Caldwell, T.E., Yu, L.S, and Weller, R.A., 2013: Surface irradiances consistent with CERES-derived top-of-atmosphere shortwave and longwave irradiances. Journal of Climate 26 (9):2719-2740. doi:Doi 10.1175/Jcli-D-12-00436.1 Wild, M., 2012: New Directions: A facelift for the picture of the global energy balance. Atmospheric Environment, 55, 366-367. Wild, M. 2012: Enlightening Global Dimming and Brightening. Bull. Amer. Meteor. Soc., 93, 27-37, d

Wild, Martin; Folini, Doris; Schär, Christoph; Loeb, Norman; König-Langlo, Gert

2014-05-01

48

A THEORY OF BIMODAL ACCELERATION OF PICKUP IONS BY COMPRESSIVE SOLAR WIND TURBULENCE UNDER PRESSURE BALANCE  

International Nuclear Information System (INIS)

Recently, it was demonstrated that stochastic acceleration of particles going through a series of compressive plasma waves can be efficient and fast. It could be too fast so that the pressure built up by the accelerated particles may in turn modify the amplitude of waves to prevent the particles from having an exploding pressure. We call this condition pressure balance. In this paper, we take into account the fact that active acceleration of particles only occupies a limited volume of space due to a possible intermittent nature of plasma waves or turbulence. We develop a bimodal acceleration theory that treats the populations of particles in the active and inactive acceleration regions separately and allows the two populations to exchange particles efficiently. Under the requirement of the pressure balance condition, we show that the system automatically produces a solution of v –5 steady state distribution for the accelerated particles. It is found that the v –5 distribution is more robust and easier to achieve with a small volume of intense particle acceleration. These properties explain why the v –5 distribution is commonly observed in space. We apply our model to pickup ion propagation and acceleration throughout the entire heliosphere. Our results can reproduce various observations in some great detail. We also found that this mechanism could be responsible for producing anomalous cosmic rays deep in the heliosheath.ays deep in the heliosheath.

49

A THEORY OF BIMODAL ACCELERATION OF PICKUP IONS BY COMPRESSIVE SOLAR WIND TURBULENCE UNDER PRESSURE BALANCE  

Energy Technology Data Exchange (ETDEWEB)

Recently, it was demonstrated that stochastic acceleration of particles going through a series of compressive plasma waves can be efficient and fast. It could be too fast so that the pressure built up by the accelerated particles may in turn modify the amplitude of waves to prevent the particles from having an exploding pressure. We call this condition pressure balance. In this paper, we take into account the fact that active acceleration of particles only occupies a limited volume of space due to a possible intermittent nature of plasma waves or turbulence. We develop a bimodal acceleration theory that treats the populations of particles in the active and inactive acceleration regions separately and allows the two populations to exchange particles efficiently. Under the requirement of the pressure balance condition, we show that the system automatically produces a solution of v {sup -5} steady state distribution for the accelerated particles. It is found that the v {sup -5} distribution is more robust and easier to achieve with a small volume of intense particle acceleration. These properties explain why the v {sup -5} distribution is commonly observed in space. We apply our model to pickup ion propagation and acceleration throughout the entire heliosphere. Our results can reproduce various observations in some great detail. We also found that this mechanism could be responsible for producing anomalous cosmic rays deep in the heliosheath.

Zhang Ming [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Schlickeiser, Reinhard [Institut fuer Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany)

2012-09-10

50

Numerical Simulation of Earth Pressure on Head Chamber of Shield Machine with FEM  

International Nuclear Information System (INIS)

Model parameters of conditioned soils in head chamber of shield machine are determined based on tree-axial compression tests in laboratory. The loads acting on tunneling face are estimated according to static earth pressure principle. Based on Duncan-Chang nonlinear elastic constitutive model, the earth pressures on head chamber of shield machine are simulated in different aperture ratio cases for rotating cutterhead of shield machine. Relationship between pressure transportation factor and aperture ratio of shield machine is proposed by using aggression analysis.

51

High Pressure Phase Transformations in Heavy Rare Earth Metals and Connections to Actinide Crystal Structures  

International Nuclear Information System (INIS)

High-pressure studies have been performed on heavy rare earth metals Terbium (Tb) to 155 GPa and Holmium (Ho) to 134 GPa in a diamond anvil cell at room temperature. The following crystal structure sequence was observed in both metals hcp ? Sm-type ? dhcp ? distorted fcc (hR-24) ? monoclinic (C2/m) with increasing pressure. The last transformation to a low symmetry monoclinic phase is accompanied by a volume collapse of 5 % for Tb at 51 GPa and a volume collapse of 3 % for Ho at 103 GPa. This volume collapse under high pressure is reminiscent of f-shell delocalization in light rare earth metal Cerium (Ce), Praseodymium (Pr), and heavy actinide metals Americium (Am) and Curium (Cm). The orthorhombic Pnma phase that has been reported in Am and Cm after f-shell delocalization is not observed in heavy rare earth metals under high pressures. (authors)

52

Strutural phase transitions in rare earth sesquioxides under pressure  

Science.gov (United States)

RE2O3 systems exist in three polymorphic forms at ambient conditions, namely: hexagonal A-type, monoclinic B-type, and cubic C-type. They show several structural phase transformations under pressure and many experimental studies have been reported in the recent times. However, the underlying mechanism which determines the stability of the cubic C-type phase for majority of the oxides under pressure and its eventual phase transformation either to the monoclinic or to the hexagonal phase has not been understood. Pressure is expected to promote the stability of A-type over C-type as the molar volume is found to decrease in the phase sequence C-B-A. In this report, the results of high pressure x-ray diffraction studies on a variety of such oxides carried out by our Group will be presented. The systematic structural transition data have been compared and contrasted with the results available for other RE2O3 systems. The correlation between the structure and stability under pressure for the C-type cubic phase will be discussed followed by the phase transition to B-type or A-type and their coexistence. The results of our DFT computation studies on Dy2O3 which corroborates the experimental results will also be presented.

Chandra Shekar, N. V.; Arulraj, A.; Sanjay Kumar, N. R.; Ravi, C.; Sekar, M.; Sahu, P. Ch.

2013-02-01

53

Integral linear momentum balance in combining flows for calculating the pressure drop coefficients  

International Nuclear Information System (INIS)

Equations for calculating the loss coefficient in combining flows in tee functions are obtained by an integral linear momentum balance. It is a practice, when solving this type of problem, to neglect the pressure difference in the upstream location as well as the wall-fluid interaction in the lateral branch of the junction. In this work it is demonstrated the influence of the above parameters on the loss coefficient based on experimental values and by apropriate algebraic manipulation of the loss coefficient values published by previous investigators. (Author)

54

Ram-pressure balance surfaces for an outwardly accelerating stellar wind bow shock  

Science.gov (United States)

We study the problem of a stellar wind bow shock (produced by an isotropic wind/plane flowing environment interaction) that lies within the wind acceleration region in the simple, ram-pressure balance approximation. We show that this problem has a simple, approximate analytic solution that produces reasonably accurate results when applied to wind velocity profiles appropriate for radiatively driven winds. These solutions should be useful for initializing numerical simulations and for evaluating whether or not the simulations are giving physically reasonable solutions. Also, our analytic solutions should be useful in the interpretation of observations without the necessity of having to perform complex numerical simulations.

Raga, A. C.; Cantó, J.; Koenigsberger, G.; Esquivel, A.

2014-10-01

55

Pressure-induced superconducting phase in rare-earth tritellurides (RTe3, R = Gd, Tb, Dy)  

International Nuclear Information System (INIS)

It has recently been reported that the low-dimensional rare-earth tritellurides RTe3 (R=La-Nd,Sm,Gd-Tm) enter an unidirectional, incommensurate charge-density-wave (CDW) state when cooled below a temperature TCDW1? 450-250 K, which decreases with increasing rare earth atomic number, due to the effect of chemical pressure. For the heavier R (i. e.: Dy-Tm), a second CDW appears at TCDW2CDW1, orthogonal to the first one. We have recently found that the application of external pressure induces a superconducting (SC) state in GdTe3, TbTe3 and DyTe3 at low temperatures, coexisting or competing with the two CDWs and the local moment rare-earth magnetism. In this talk, we present the results of experiments we have performed on these materials at high pressure and low temperature, to help develop an understanding of the origin of the superconducting state.

56

Impact of Interactive Energy-Balance Modeling on Student Learning in a Core-Curriculum Earth Science Course  

Science.gov (United States)

An interactive instructional module has been developed to study energy balance at the earth's surface. The module uses a graphical interface to model each of the major energy components involved in the partitioning of energy at this surface: net radiation, sensible and latent heat fluxes, ground heat flux, heat storage, anthropogenic heat, and advective heat transport. The graphical interface consists of an energy-balance diagram composed of sky elements, a line or box representing the air or sea surface, and arrows which indicate magnitude and direction of each of the energy fluxes. In April 2005 an energy-balance project and laboratory assignment were developed for a core-curriculum earth science course at Clark Atlanta University. The energy-balance project analyzes surface weather data from an assigned station of the Georgia Automated Environmental Monitoring Network (AEMN). The first part of the project requires the student to print two observations of the "Current Conditions" web page for the assigned station: one between the hours of midnight and 5:00 a.m., and the other between the hours of 3:00- 5:00 p.m. A satellite image of the southeastern United States must accompany each of these printouts. The second part of the project can be completed only after the student has modeled the 4 environmental scenarios taught in the energy-balance laboratory assignment. The student uses the energy-balance model to determine the energy-flux components for each of the printed weather conditions at the assigned station. On successful completion of the project, the student has become familiar with: (1) how weather observations can be used to constrain parameters in a microclimate model, (2) one common type of error in measurement made by weather sensors, (3) some of the uses and limitations of environmental models, and (4) fundamentals of the distribution of energy at the earth's surface. The project and laboratory assignment tie together many of the earth science concepts taught in the course: geology (soils), oceanography (surface mixed layer), and atmospheric science (meteorology of the lowest part of the atmosphere). Details of the project and its impact on student assessment tests and surveys will be presented.

Mandock, R. L.

2008-12-01

57

Negative-pressure-induced collector for a self-balance free-flow electrophoresis device.  

Science.gov (United States)

Uneven flow in free-flow electrophoresis (FFE) with a gravity-induced fraction collector caused by air bubbles in outlets and/or imbalance of the surface tension of collecting tubes would result in a poor separation. To solve these issues, this work describes a novel collector for FFE. The collector is composed of a self-balance unit, multisoft pipe flow controller, fraction collector, and vacuum pump. A negative pressure induced continuous air flow rapidly flowed through the self-balance unit, taking the background electrolyte and samples into the fraction collector. The developed collector has the following advantages: (i) supplying a stable and harmonious hydrodynamic environment in the separation chamber for FFE separation, (ii) effectively preventing background electrolyte and sample flow-back at the outlet of the chamber and improving the resolution, (iii) increasing the preparative scale of the separation, and (iv) simplifying the operation. In addition, the cost of the FFE device was reduced without using a multichannel peristaltic pump for sample collection. Finally, comparative FFE experiments on dyes, proteins, and cells were carried out. It is evident that the new developed collector could overcome the problems inherent in the previous gravity-induced self-balance collector. PMID:24648284

Yang, Cheng-Zhang; Yan, Jian; Zhang, Qiang; Guo, Chen-Gang; Kong, Fan-Zhi; Cao, Cheng-Xi; Fan, Liu-Yin; Jin, Xin-Qiao

2014-06-01

58

High Pressure, Earth-storable Rocket Technology. Volume 1  

Science.gov (United States)

The effect of elevated chamber pressure on combustion efficiency and heat transfer has been determined at the 100 lbf (445 N) thrust level for nitrogen tetroxide propellants. Measurements were made up to 500 psia (3.45 MPa) with testbed hardware; tests at 100 psia (0.690 MPa) and 250 psia (1.72 MPa) were made with radiation-cooled rhenium chambers. The first task of the program served to determine desirable thruster applications and operating conditions: high total impulse, i.e., communication satellite or spacecraft bus axial engines, at chamber pressures up to 250 psia (1.72 MPa) pressure-fed, or up to 500 psia (3.45 MPa) pump-fed. The hardware modifications and testing required to obtain the data were determined in Task 2, which included design-support hot fire tests; supplemental hardware, including a 250 psia (1.72 MPa) Pc rhenium chamber and a 20% fuel-film cooled platelet injector was fabricated in Task 3. Testing showed that satisfactory operation of Ir-Re radiation chambers is assured at pressures up to 250 psia and may be possible up to 500. The heat transfer data obtained show good correlation with throat Reynolds number and are generally under values given by the simplified Bartz equation; chambers equilibrium temperatures match predicted values. Preliminary optimization of trip configuration and mixture ratio were made; Isp performance from thrust measurements was within 1% of predicted values. Stability, compatibility, and front-end thermal management were determined to be satisfactory.

Jassowski, D. M.

1997-01-01

59

High Pressure, Earth-storable Rocket Technology. Volume 2  

Science.gov (United States)

The effect of elevated chamber pressure on combustion efficiency and heat transfer has been determined at the 100 lbf (445 N) thrust level for nitrogen tetroxide propellants. Measurements were made up to 500 psia (3.45 Mpa) with testbed hardware; tests at 100 psia (0.690 MPa) and 250 psia (1.72 MPa) were made with radiation-cooled rhenium chambers. The first task of the program served to determine desirable thruster applications and operating conditions: high total impulse, i.e. communication satellite or spacecraft bus axial engines, at chamber pressures up to 250 psia (1.72 MPa) pressure-fed, or up to 500 psia (3.45 MPa) pump-fed. The hardware modifications and testing required to obtain the data were determined in Task 2, which included design-support hot fire tests; supplemental hardware, including a 250 psia (1.72 MPa) Pc rhenium chamber and a 20% fuel-film cooled platelet injector was fabricated in Task 3. Testing showed that satisfactory operation of Ir-Re radiation chambers is assured at pressures up to 250 psia and may be possible up to 500. The heat transfer data obtained show good correlation with throat Reynolds number and are generally under values given by the simplified Bartz equation; chambers equilibrium temperatures match predicted values. Preliminary optimization of trip configuration and mixture ratio were made; Isp performance from thrust measurements was within 1% of predicted values. Stability, compatibility, and front-end thermal management were determined to be satisfactory.

Jassowski, D. M.

1997-01-01

60

A perfectly balanced method for estimating the internal pressure gradients in ?-coordinate ocean models  

Science.gov (United States)

The estimation of the internal pressure gradients (IPG) in ?-coordinate ocean models has been addressed both in text books and in many research papers. In this paper a perfectly balanced method for estimating internal density and pressure gradients is suggested. The method is perfect in the sense that for cases with ? = ?( z), where ? is density and z the vertical coordinate, the numerical estimates of the density and pressure gradients are zero. The method has in addition another important property: for continuous stratification, the estimates of the internal pressure gradients vary continuously with changes in the stratification. The properties of the method are investigated using two very simple vertical column test cases, the seamount case, and two Nordic Seas test cases, one with ? = ?( z) and another more realistic case with ? = ?( x, y, z). For the seamount case and the simple Nordic Seas case, the errors are orders of magnitude smaller than the corresponding errors reported in earlier papers. For the simple vertical column case with non-zero density gradients, the estimates of the gradients produced with the new method converge quadratically towards the true values as the horizontal and vertical grid sizes both tend to zero. The new method may be regarded as a modified second order method calibrated such that the errors are zero for ? = ?( z).

Berntsen, Jarle

 
 
 
 
61

The role of pressure solution creep in the ductility of the earth's upper crust  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this review is to characterize the role of pressure solution creep in the ductility of the Earth's upper crust and to describe how this creep mechanism competes and interacts with other deformation mechanisms. Pressure solution creep is a major mechanism of ductile deformation of the upper crust, accommodating basin compaction, folding, shear zone development, and fault creep and interseismic healing. However, its kinetics is strongly dependent on the composition of the rocks (main...

Gratier, Jean-pierre; Dysthe, Dag; Renard, Francois

2013-01-01

62

Hypothermic machine perfusion of the liver and the critical balance between perfusion pressures and endothelial injury.  

Science.gov (United States)

Hypothermic machine perfusion (HMP) provides better protection against cold ischemic injury than cold storage in marginal donor kidneys. Also, in liver transplantation a switch from static cold storage to HMP could be beneficial as it would allow longer preservation times and the use of marginal donors. A critical question concerning application of HMP in liver preservation is the crucial balance between perfusion pressure and occurrence of endothelial injury. Rat livers were cold-perfused for 24 hours to study perfusion pressures for both hepatic artery and portal vein. Cold storage served as control and was compared to HMP-preserved livers using a mean arterial perfusion pressure of 25 mm Hg and a portal perfusion pressure of 4 mm Hg (25% of normothermic liver circulation) and to HMP at 50 mm Hg and 8 mm Hg perfusion, respectively (50% of normothermic liver circulation). UW solution was enriched with 14.9 micromol/L propidium iodide (PI) to stain for dead cells and with an additional 13.5 micromol/L acridine orange to stain for viable hepatocytes. A low PI-positive cell count was found using HMP at 25% of normal circulation compared to cold storage. The PI count was high for the HMP group perfused at just 50% of normal circulation compared to HMP at 25% and compared to cold storage. In summary, for liver HMP, perfusion at 25% showed complete perfusion with minimal cellular injury. HMP using perfusion pressures of 25 mm Hg for the hepatic artery and 4 mm Hg for the portal vein is feasible without induction of endothelial injury. PMID:15808634

't Hart, N A; van der Plaats, A; Leuvenink, H G D; van Goor, H; Wiersema-Buist, J; Verkerke, G J; Rakhorst, G; Ploeg, R J

2005-01-01

63

A Plantar-pressure Based Tongue-placed Tactile Biofeedback System for Balance Improvement  

CERN Document Server

Maintaining an upright stance represents a complex task, which is achieved by integrating sensory information from the visual, vestibular and somatosensory systems. When one of these sensory inputs becomes unavailable and/or inaccurate and/or unreliable, postural control generally is degraded. One way to solve this problem is to supplement and/or substitute limited/altered/missing sensory information by providing additional sensory information to the central nervous system via an alternative sensory modality. Along these lines, we developed an original biofeedback system [1] whose underlying principle consists in supplying the user with supplementary sensory information related to foot sole pressure distribution through a tongue-placed output device (Tongue Display Unit, "TDU" [2]). The purpose of the present experiment was to assess its effectiveness in improving balance in young healthy adults.

Vuillerme, Nicolas; Pinsault, Nicolas; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

2007-01-01

64

The pressure and energy balance of the cool corona over sunspots  

Science.gov (United States)

The 22 largest sunspots observed with the Skylab SO55 spectrometer are studied for a relation between their EUV radiation and their umbral size or magnetic classification. The ultimate goal is to determine why the coronal plasma is so cool over a sunspot and how this cool plasma manages to support itself against gravity. Based on the time behavior of the EUV emission, a steady-state model is developed for the pressure and energy balance of the cool coronal-plasma loops over the spots. Analysis of the temperature structure in a typical loop indicates that the loop is exceedingly well insulated from the outside corona, that its energy balance is determined purely by internal heating and cooling processes, and that a heat input of about 0.0001 erg/cu cm per sec is required along the full length of the loop. It is proposed that: (1) coronal material flows steadily across the field lines at the tops of the loops and falls downward along both sides under gravity; (2) the corona is heated by mechanical-energy transport across the very thin transition region immediately over network-cell interiors; and (3) strong magnetic fields tend to inhibit mechanical-energy dissipation in the corona.

Foukal, P. V.

1976-01-01

65

Structural phase transitions of rare earth monophosphides with NaCl-type structure under high pressures  

Energy Technology Data Exchange (ETDEWEB)

Rare earth monophosphides REP (RE=La, Ce, Pr, Nd, Sm, Gd, Tb, Tm and Yb) crystallize in a NaCl-type structure at ambient pressure. Using synchrotron radiation X-ray diffractions of REP have been studied up to about 60 GPa at room temperature. All phosphides are found to undergo structural phase transitions at high pressures. The high pressure phases of LaP, PrP and NdP can be assigned to be a tetragonal structure, which can be seen as the distorted CsCl-type structure. The pressure-induced phase transitions of SmP, GdP, TbP, TmP and YbP occur at around 35, 40, 38, 53 and 51 GPa, respectively. The structure of the high pressure phases is unknown. X-ray diffraction patterns of the compounds with many f-electrons become more complex at high pressure. It is expected that 4f-electrons in rare earth atoms influence the structure of the high pressure phases. (author)

Adachi, Takafumi (Institute for Molecular Science, Okazaki, Aichi (Japan)); Shirotani, Ichimin; Shimomura, Osamu

1999-04-01

66

Structural phase transitions of rare earth monophosphides with NaCl-type structure under high pressures  

International Nuclear Information System (INIS)

Rare earth monophosphides REP (RE=La, Ce, Pr, Nd, Sm, Gd, Tb, Tm and Yb) crystallize in a NaCl-type structure at ambient pressure. Using synchrotron radiation X-ray diffractions of REP have been studied up to about 60 GPa at room temperature. All phosphides are found to undergo structural phase transitions at high pressures. The high pressure phases of LaP, PrP and NdP can be assigned to be a tetragonal structure, which can be seen as the distorted CsCl-type structure. The pressure-induced phase transitions of SmP, GdP, TbP, TmP and YbP occur at around 35, 40, 38, 53 and 51 GPa, respectively. The structure of the high pressure phases is unknown. X-ray diffraction patterns of the compounds with many f-electrons become more complex at high pressure. It is expected that 4f-electrons in rare earth atoms influence the structure of the high pressure phases. (author)

67

Exposure of phototrophs to 548 days in low Earth orbit: microbial selection pressures in outer space and on early earth.  

Science.gov (United States)

An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated with the natural community survived. Of the augmented organisms, cells of A. cylindrica and Chroococcidiopsis survived, but no cells of N. commune. Only cells of Chroococcidiopsis were cultured from samples exposed to the unattenuated extraterrestrial ultraviolet (UV) spectrum (>110?nm or 200?nm). Raman spectroscopy and bright-field microscopy showed that under these conditions the surface cells were bleached and their carotenoids were destroyed, although cell morphology was preserved. These experiments demonstrate that outer space can act as a selection pressure on the composition of microbial communities. The results obtained from samples exposed to >200?nm UV (simulating the putative worst-case UV exposure on the early Earth) demonstrate the potential for epilithic colonization of land masses during that time, but that UV radiation on anoxic planets can act as a strong selection pressure on surface-dwelling organisms. Finally, these experiments have yielded new phototrophic organisms of potential use in biomass and oxygen production in space exploration. PMID:21593797

Cockell, Charles S; Rettberg, Petra; Rabbow, Elke; Olsson-Francis, Karen

2011-10-01

68

Studies on the Stability of the Industrial Pressure Balances for Hydrostatic Pressure Measurement up to 100 MPa  

Science.gov (United States)

In the present paper, the results on the study, carried out on industrial pressure balance (PB) have been reported, which was characterized at NPL twice. The results thus obtained are also compared with the values reported by the manufacturer at the time of procurement and the stability of the effective area is established for the last seven years. Further studies were carried out on the same type and model of PBs as previous PB, being used by different users at two different locations. It is observed that there is a small change in the short term stability but the change is prominent in case of long term stability. However, such changes are well within the estimated measurement uncertainty of the instrument. The change in effective area is quite significant for the identical models at three different locations in India i.e. in Delhi (north), Chennai (south) and Guwahati (west), due to obvious reasons of different form geometry of the p-c assemblies. However, the behavior of effective area is found similar at all the three locations. The causes for such behaviours are described.

Yadav, S.; Gupta, V. K.; Kumar, L.; Bandyopadhyay, A. K.

2013-01-01

69

Measuring the initial earth pressure of granite using hydraulic fracturing test; Goseong and Yuseong areas  

Energy Technology Data Exchange (ETDEWEB)

This report provides the initial earth pressure of granitic rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are obtained by hydraulic fracturing test in three boreholes drilled up to 350{approx}500 m depth at the Yuseong and Goseong sites. These sites were selected based on the result of preliminary site evaluation study. The boreholes are NX-size (76 mm) and vertical. The procedure of hydraulic fracturing test is as follows: - Selecting the testing positions by preliminary investigation using BHTV logging. - Performing the hydraulic fracturing test at each selected position with depth.- Estimating the shut-in pressure by the bilinear pressure-decay-rate method. - Estimating the fracture reopening pressure from the pressure-time curves.- Estimating the horizontal principal stresses and the direction of principal stresses. 65 refs., 39 figs., 12 tabs. (Author)

Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Won, Kyung Sik [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-02-01

70

Elastic, thermal and high pressure structural properties of heavy rare earth antimonides  

International Nuclear Information System (INIS)

Pressure induced structural phase transition of two heavy rare earth antimonides (RESb; RE=Ho, Er) have been studied theoretically by using an inter-ionic potential theory. This method has been found quite satisfactory in the case of pnictides of rare earth and describes the crystal properties in the framework of rigid-ion modal. The long-range Coulomb interaction, short-range repulsive interaction and van der Waals (vdW) interactions are properly incorporated in this theory. These compounds exhibit first order crystallographic phase transition from their NaCl-type structure to CsCl-type structure at 27 GPa and 33.2 GPa, respectively. The bulk moduli of RESb compounds are compared with the experimental values of elastic constants. We have also calculated the Debye temperature by incorporating the elastic constants for both the rare earth antimonides. (author)

71

Double molybdates and tungstates of alkali metal compounds and rare earths synthesized at high pressure  

International Nuclear Information System (INIS)

By using X-ray phase analysis methods, double molybdates and tungstates of alkali and rare earths elements of composition MLn(EO4)2 have been produced, synthesized under a high pressure (about 25 to 80 kbars) and at temperatures of 800 to 1000 deg C. It has been shown that characteristic of those compounds with light alkali metals (Li) is the structural type of tungstate, and that compounds with heavy alkali metals (K-C) are crystallized under a high pressure in a structure which is similar to P-KV(WO4)2

72

Ultra-high pressure phase transformations in light rare earth metals  

Science.gov (United States)

The rare earth metals, also known as the lanthanide series, are characterized by the filling of the 4f shell. When pressure is employed as the primary variable, the behavior of rare earth metals becomes very interesting. As pressure increases, the inter-atomic distances decrease substantially because of the high compressibility of rare earth metals. This has significant effects on their structural and electronic properties. The low-pressure structural sequence for trivalent rare earth metals is well documented below 40 GPa. hexagonal close packed (hcp) ?samarium (Sm )-type?double hcp ? face-centered cubic (fcc) The post-fcc phases are of great interest but are difficult to observe because of the ultra-high pressures required and extremely small sample volumes. Diamond anvil cell (DAC) technology and its combination with synchrotron radiation has made it possible to attain ultra-high pressures and study crystalline phase transformations by x-ray diffraction. In particular, I will focus on the post-fcc phases of the light rare earth metals, praseodymium (Pr), neodymium, Sm, and gadolinium (Gd). Praseodymium was studied at room temperature in a DAC up to 103 GPa by energy dispersive x-ray diffraction (EDXD) using a synchrotron source. A new structure observed at 10--12 GPa is referred to as monoclinic C2/m with 4 atoms/cell. At 20 GPa, a previously known volume collapse was monitored from the monoclinic C2/m structure to the orthorhombic alpha-U structure. However, an unusually high volume collapse of 16.7% was measured which is generally associated with f delocalization. Neodymium was studied to 155 GPa in a DAC using EDXD with a synchrotron source. A new phase transformation from the monoclinic C2/m phase to the orthorhombic alpha-U phase was observed at 113 +/- 6 GPa without any observable volume collapse. Samarium has been studied to the highest pressure of 205 GPa in a DAC using EDXD with a synchrotron source. A new phase transformation from hP3 (hexagonal, 3 atoms/cell) to C2/m was observed at 103 +/- 5 GPa with no volume discontinuities. Gadolinium was studied to 235 GPa in a DAC with EDXD with a synchrotron source. The monoclinic C2/m structure had not been previously observed in Gd. Also, the phase transformation of C2/m ? body-centered monoclinic (bcm) occurred with a 9.4% volume collapse.

Chesnut, Gary Neal

2001-07-01

73

Magnetic cooling by the application of external pressure in rare-earth compounds  

Science.gov (United States)

A method for cooling by the application of pressure was recently proposed. As in any other (magnetic) adiabatic cooling technique, the cooling results from a change in the magnetic entropy of the system under investigation. As opposed to the well known method of adiabatic demagnetization (for paramagnets) or to the magnetocaloric effect (for ferromagnets and antiferromagnets), the entropy change does not result from the application of an external magnetic field, but from the application of external pressure (barocaloric effect). The pressure-induced change in the magnetic entropy may be obtained by different mechanisms including pressure-induced structural or/and magnetic phase transitions, pressure-induced changes in the degree of 4f-conduction electron hybridization in Kondo systems, pressure-induced valence transitions, and pressure-induced spin fluctuations. The present work illustrates this new concept of adiabatic cooling on the basis of recent experimental data. The data are discussed within a simple model balancing the total entropy as a function of microscopic thermodynamic parameters of the system under investigation. Implications for a possible technical use of this effect are addressed.

Strässle, Th.; Furrer, A.; Hossain, Z.; Geibel, Ch.

2003-02-01

74

THE INFLUENCE OF PRESSURE-DEPENDENT VISCOSITY ON THE THERMAL EVOLUTION OF SUPER-EARTHS  

International Nuclear Information System (INIS)

We study the thermal evolution of super-Earths with a one-dimensional (1D) parameterized convection model that has been adopted to account for a strong pressure dependence of the viscosity. A comparison with a 2D spherical convection model shows that the derived parameterization satisfactorily represents the main characteristics of the thermal evolution of massive rocky planets. We find that the pressure dependence of the viscosity strongly influences the thermal evolution of super-Earths—resulting in a highly sluggish convection regime in the lower mantles of those planets. Depending on the effective activation volume and for cooler initial conditions, we observe with growing planetary mass even the formation of a conductive lid above the core-mantle boundary (CMB), a so-called CMB-lid. For initially molten planets our results suggest no CMB-lids but instead a hot lower mantle and core as well as sluggish lower mantle convection. This implies that the initial interior temperatures, especially in the lower mantle, become crucial for the thermal evolution—the thermostat effect suggested to regulate the interior temperatures in terrestrial planets does not work for massive planets if the viscosity is strongly pressure dependent. The sluggish convection and the potential formation of the CMB-lid reduce the convective vigor throughout the mantle, thereby affecting convective stresses, lithospheric thicknesses, and heat fluxes. The pressure dependence of the viscosity pressure dependence of the viscosity may therefore also strongly affect the propensity of plate tectonics, volcanic activity, and the generation of a magnetic field of super-Earths.

75

Engineering kinematic theory of the contact earth pressure and its application to the static calculation of thin quay walls  

Directory of Open Access Journals (Sweden)

Full Text Available Construction of deep-water thrust berthing structures requires using new and more perfect methods of calculation containing fewer assumptions. A version of the engineering kinematic theory of contact earth pressure in the application to the water-transport and offshore structures was suggested in the article. A dimensionless static “compression – tension” diagram of the soil, presented by curvilinear function, was used in the method. In this case, the displacement of the limit point of the diagram is determined with the account of the plastic deformation modulus in the earth contact point. Practical application of engineering theory was implemented in the proposed method of the mirroring with respect to anchored thin walls. In this method different lateral pressure profiles depending on the rated scheme were used. This method consists in three steps’ loading of anchored wall. The first stage – the normal calculation of the wall in the form of beam loaded by active earth pressure and bearing on the anchor pole and partly on the base ground. The second stage – the anchor reaction and the foundation earth reactive pressure are mirrored in the form of external loads acting on the part of the water area on the beam bearing on the backfill and foundation soil. Third stage – repeating the first external load in the form of the earth pressure profile behind the wall derived in the second calculation step. Suggested calculation as distinct from existing methods, which are using active earth pressure, defines more exactly the strains in retaining wall upward or downward.

V.S. Korovkin

2013-10-01

76

Direct solar radiation pressure on the orbits of small near-Earth asteroids: observable effects?  

Science.gov (United States)

We consider the perturbations of Near-Earth Asteroid orbits due to direct solar radiation pressure (both the absorption and the reflection components). When the body is spherical and the surface albedo homogeneous the effect is small (and only short-periodic). However, when at least one of these restrictive and unrealistic assumptions is relaxed, long-term orbital effects appear and they may potentially lead to observable displacement of the orbit. We illustrate this conclusion by computing the orbital perturbations due to radiation pressure for objects with an odd-zonal distribution of albedo and for objects with ellipsoidal shape. Especially in the first case the effects are large, due to the long-term perturbations of the semimajor axis. For high-eccentricity orbits observed over a long interval of time, the (v/c)-correction of the direct radiation pressure, known as Poynting-Robertson effect, should be also considered. As an example we demonstrate that for the asteroid 1566 Icarus, during its next close approach to the Earth, the orbit displacement due to the direct solar radiation forces might be, under reasonable assumptions, comparable to the orbit determination uncertainty, thus potentially observable.

Vokrouhlický, D.; Milani, A.

2000-10-01

77

Evaluation of subsurface fracture geometry using fluid pressure response to solid earth tidal strain  

Energy Technology Data Exchange (ETDEWEB)

The nature of solid earth tidal strain and surface load deformation due to the influence of gravitational forces and barometric pressure loading are discussed. The pore pressure response to these types of deformation is investigated in detail, including the cases of a confined aquifer intersected by a well and a discrete fracture intersected by a well. The integration of the tidal response method with conventional pump tests in order to independently calculate the hydraulic parameters of the fracture-formation system is discussed. How advanced spectral analysis methods, coupled with correlation analysis can be used to extract the tidal response signals from the pressure record is shown. Uncertainties in the signals are estimated using various information-theoretic methods in order to place a confidence level at which we can safely assume that the measured signal is indeed of tidal origin. A detailed case study of the method carried out at the Raft River Geothermal Reservoir in Idaho is presented. All of the analyzed tidal data is presented and the results of the computed fracture orientation using the solid earth tidal strain approach are compared with the extensive field work carried out at Raft River over the past decade. The direction that future work in the continuing development of this technology should take is discussed, including: (1) the present need for an expanded data base for the confirmation of present tidal strain response models, and (2) improvement in response models.

Hanson, J.M.

1984-09-01

78

Pressure change associated with dipolarization in the near-earth plasma sheet  

International Nuclear Information System (INIS)

Complete text of publication follows. We have studied pressure changes that occur in association with dipolarization in the plasma sheet of the near-Earth magnetotail around substorm onsets. We performed a superposed epoch analysis using Geotail data. Here the contribution of high-energy particles to the ion pressure was considered. It is found that, unlike the previously reported results, the ion pressure increases in association with dipolarization at X ? -10 Re where the initial dipolarization takes place. This pressure change is largely contributed by high-energy particles. Tailward of this region, the ion pressure does not significantly increase even after the beginning of dipolarization, while it decreases in some cases; in both cases, the contribution of high-energy particles is not very large. Furthermore, the ion beta enhances around substorm expansion onset in the close vicinity of the magnetic equator of the initial dipolarization region. These observations suggest that the characteristics of the dipolarization differ between the initial dipolarization and tailward regions. We also examine in detail a few individual cases that were observed by Geotail and THEMIS in the vicinity of the magnetic equator. We also discuss implications for the rarefaction wave proposed in the current disruption model.

79

High Pressure Earth Storable Rocket Technology Program-Hipes Options 1/2 Report  

Science.gov (United States)

Under the High Pressure Earth Storable Rocket Technology (HIPES) Program, TRW successfully completed testing of two 100 lbf thrust class rhenium chambers using N204-MMH. The first chamber was successfully fired for 4789 seconds of operating time with a maximum duration of 700 seconds. This chamber had been previously fired for 5230 seconds with N2O4-N2H4. The second chamber was successfully fired for 8085 seconds with a maximum firing duration of 1200 seconds. The Isp (specific impulse) for both chambers ranged from 323 lbf-sec/lbm to 330 lbf-sec/lbm.

Chazen, M. L.; Sicher, D.; Calvignac, J.; Ono, D.

1999-01-01

80

Lateral Earth Pressure at Rest and Shear Modulus Measurements on Hanford Sludge Simulants  

Energy Technology Data Exchange (ETDEWEB)

This report describes the equipment, techniques, and results of lateral earth pressure at rest and shear modulus measurements on kaolin clay as well as two chemical sludge simulants. The testing was performed in support of the problem of hydrogen gas retention and release encountered in the double- shell tanks (DSTs) at the Hanford Site near Richland, Washington. Wastes from single-shell tanks (SSTs) are being transferred to double-shell tanks (DSTs) for safety reasons (some SSTs are leaking or are in danger of leaking), but the available DST space is limited.

Wells, Beric E.; Jenks, Jeromy WJ; Boeringa, Gregory K.; Bauman, Nathan N.; Guzman, Anthony D.; Arduino, P.; Keller, P. J.

2010-09-30

 
 
 
 
81

The Coupled Effects of Pressure and Mineralogy on the Dynamics of Axisymmetric Thermochemical Plumes in the Earth's Lower Mantle  

Science.gov (United States)

Mass balance considerations based on chondrites compositions as well as the observed anticorrelation between bulk sound and shear wave velocities suggest that a significant part of the deep mantle is enriched in Si and Fe, relative to the bulk mantle composition. Several numerical studies and laboratory experiments have shown that the presence of these compositional heterogeneities may have a first order impact on the dynamics of ascending mantle plumes, through their induced chemical density contrast ? ??/? with respect to the surrounding mantle. However, using mineral physics data and thermodynamic considerations, we first show that contrary to what was assumed in previous geodynamic studies, ? ??/? may significantly vary with pressure in the lower mantle (up to 200% variation), depending on the Si and Fe content of the chemically distinct material. We therefore investigate the coupled effects of mineralogy and pressure on the dynamics of axisymmetric thermochemical plumes in the Earth's lower mantle, using both high resolution numerical experiments and analytical theory. Our results show that the effect of mineralogy is considerable: (1) For relatively low Si enrichment, an oscillatory behavior of the plume head is observed, similar to previous laboratory experiments [Davaille, Nature, 402, 756-760, (1999)] but without the need of large volume of chemically distinct material. (2) For Si-enriched compositions with respect to a reference pyrolitic mantle, the chemical density excess increases with decreasing depth, leading to the stagnation of large plume heads at various depths in the lower mantle. As a consequence, these thermochemical plumes may display broad (~ 1200 km wide and more) negative seismic velocity anomalies at various lower mantle depths, which may not necessarily be associated with upwelling currents. In addition, the coupling between mineralogy and dynamics may provide an efficient mechanism for the long term survival of compositional heterogeneity in the lower mantle, as suggested by geophysical observations and geochemical record.

Samuel, H.; Bercovici, D.

2005-12-01

82

Local structure around rare-earth ions in B2O3 glass at high pressure  

International Nuclear Information System (INIS)

Melt quenching of B2O3 with less than 25 mol. % rare-earth oxide (RE2O3) at ambient pressure results in a milky white glass because of liquid-liquid phase separation into B2O3 and RE2O3·3B2O phases. In contrast, we have found that melt quenching under GPa-order pressure realizes a transparent RE-doped B2O3 glass. This study investigates the local structure around the RE ions in the B2O3 glass prepared at 3 GPa using optical measurements and electron-spin-echo envelope modulation spectroscopy. It is shown that the RE-rich microparticles disappear and the RE ions are isolated from each other in a highly symmetric crystal field formed by triangular and tetrahedral boron units. This result is consistent with that extrapolated from the data for RE-doped sodium borate glasses.

83

Local structure around rare-earth ions in B2O3 glass at high pressure  

Science.gov (United States)

Melt quenching of B2O3 with less than 25 mol. % rare-earth oxide (RE2O3) at ambient pressure results in a milky white glass because of liquid-liquid phase separation into B2O3 and RE2O3.3B2O phases. In contrast, we have found that melt quenching under GPa-order pressure realizes a transparent RE-doped B2O3 glass. This study investigates the local structure around the RE ions in the B2O3 glass prepared at 3 GPa using optical measurements and electron-spin-echo envelope modulation spectroscopy. It is shown that the RE-rich microparticles disappear and the RE ions are isolated from each other in a highly symmetric crystal field formed by triangular and tetrahedral boron units. This result is consistent with that extrapolated from the data for RE-doped sodium borate glasses.

Funabiki, Fuji; Matsuishi, Satoru; Hosono, Hideo

2013-06-01

84

Lifshitz and other transitions in alkaline-earth 122 pnictides under pressure  

Science.gov (United States)

We carry out T =0 first-principles total energy calculations in the entire set of alkaline 122-pnictides (A Fe2As2 ; A = alkaline-earth element Ca, Sr, Ba, Ra) as a function of hydrostatic pressure. We find multiple distinct transitions to occur, namely an enthalpic transition in which the zero-pressure striped antiferromagnetic orthorhombic (OR-AFM) phase becomes thermodynamically less stable than a competing tetragonal (T) phase, a magnetic transition in which the OR-AFM phase loses its magnetism and orthorhombicity, and a lattice parameter anomaly in which the tetragonal c-axis collapses and a collapsed tetragonal (cT) phase becomes stable. Our results for energy band dispersions and spectra, lattice parameters, enthalpies, magnetism, and elastic constants over a wide range of hydrostatic pressure provide a coherent understanding of these experimentally observed transitions. In particular, the T-cT transition and anomalies in lattice parameters and elastic properties, observed at finite temperatures, are interpreted as arising from proximity to T =0 Lifshitz transitions, wherein pressure causes nontrivial changes in the Fermi surface topology in these materials.

Quader, Khandker; Widom, Michael

2014-10-01

85

Validating and calibrating the Nintendo Wii balance board to derive reliable center of pressure measures.  

Science.gov (United States)

The Nintendo Wii balance board (WBB) has generated significant interest in its application as a postural control measurement device in both the clinical and (basic, clinical, and rehabilitation) research domains. Although the WBB has been proposed as an alternative to the "gold standard" laboratory-grade force plate, additional research is necessary before the WBB can be considered a valid and reliable center of pressure (CoP) measurement device. In this study, we used the WBB and a laboratory-grade AMTI force plate (AFP) to simultaneously measure the CoP displacement of a controlled dynamic load, which has not been done before. A one-dimensional inverted pendulum was displaced at several different displacement angles and load heights to simulate a variety of postural sway amplitudes and frequencies (<1 Hz). Twelve WBBs were tested to address the issue of inter-device variability. There was a significant effect of sway amplitude, frequency, and direction on the WBB's CoP measurement error, with an increase in error as both sway amplitude and frequency increased and a significantly greater error in the mediolateral (ML) (compared to the anteroposterior (AP)) sway direction. There was no difference in error across the 12 WBB's, supporting low inter-device variability. A linear calibration procedure was then implemented to correct the WBB's CoP signals and reduce measurement error. There was a significant effect of calibration on the WBB's CoP signal accuracy, with a significant reduction in CoP measurement error (quantified by root-mean-squared error) from 2-6 mm (before calibration) to 0.5-2 mm (after calibration). WBB-based CoP signal calibration also significantly reduced the percent error in derived (time-domain) CoP sway measures, from -10.5% (before calibration) to -0.05% (after calibration) (percent errors averaged across all sway measures and in both sway directions). In this study, we characterized the WBB's CoP measurement error under controlled, dynamic conditions and implemented a linear calibration procedure for WBB CoP signals that is recommended to reduce CoP measurement error and provide more reliable estimates of time-domain CoP measures. Despite our promising results, additional work is necessary to understand how our findings translate to the clinical and rehabilitation research domains. Once the WBB's CoP measurement error is fully characterized in human postural sway (which differs from our simulated postural sway in both amplitude and frequency content), it may be used to measure CoP displacement in situations where lower accuracy and precision is acceptable. PMID:25268919

Leach, Julia M; Mancini, Martina; Peterka, Robert J; Hayes, Tamara L; Horak, Fay B

2014-01-01

86

Petrography and alteration of Chehelkureh copper deposit: Mass balance of elements and behavior of rare earth elements  

International Nuclear Information System (INIS)

Chehelkureh copper deposit is located in Kuh-e-Lunka area, 120 km Northwest of Zahedan (Southeast of Iran). The host rocks of mineralization are intercalated Eocene turbiditic greywackes, siltstones, and shales (flysch). They are folded with N-S trend and the eastern limb of this fold has been drag folded. Several stocks and dykes of granodiorite to quartz monzodiorite and granite compositions intruded the turbidites, converting them locally to hornfels. These intrusions are oriented parallel to the major Northwest-Southeast fault set. The Chehelkureh are field comprises numerous irregular lenses and veins. The ore field extends for 1500 meters in N23degW direction, and is displaced by late brittle faults striking roughly East-West. The fault and fracture filling ores include quartz, dolomite, ankerite, siderite, calcite, and lesser amounts of pyrrhotite, arsenopyrite, pyrite, chalcopyrite, sphalerite, galena, Se-rich galena, marcasite, molybdenite, ilmenite, and rutile. Assay data from 39 drill holes show high contents of base metals, with an average of 1.48% Cu, 1.77% Zn, 0.85% Pb (4.1% Cu + Zn + Pb), and silver (average 22 ppm in 45 samples). The ores are not so enriched in gold (0.14 ppm on average in 45 samples). A composite sample of least-altered greywackes and shales (host rocks) is used for comparison with mineralized samples. Mass-balance calculations were carried out to quantify chemical changes resulting from different alteration episs resulting from different alteration episodes. With the low solubility and low variance of Al (Al2O3) in moderately altered sedimentary country rocks compared with many other immobile trace components, Al2O3 is used as an immobile component for mass-balance calculations. There is a net mass increase in Fe2O3T, and Mg O and a net mass decrease in Na2O, Ca O, K2O, and, SiO2 with chloritization. Carbonatization shows Fe2O3T. and Mg O enrichment and SiO2 and Na2O depletion, implying that ankerite, siderite and dolomite are predominant phases. SiO2 is enriched in silicified samples and depleted in other alteration types. There is no mass change in Cu, Pb and Zn with kaolinization, but these elements are enriched in other alteration types. Hg is enriched in all alteration types except kaolinization, which may even show a slight depletion. Samples from gossan with siIicifcation showedanincrease in SiO2, Fe2O3T, Cu, Pb, Hg, and Znandadecrease in Mg O, Na2O,Ca O, and K2O. Sometraceandmajor elements have high variance in different alterations and are more complicated to interpret, such as P2O5, Mn O, Ni, CO, and Rb. The rare earth element contents of the composite host rock sample are enriched in the LREE relative to the HREE and moderately depleted in Eu and Ho. As a whole, samples with kaolinization and carbonatization (ankerite and siderite) have been enriched in rare earth element contents and other wallrock alteration, including chloritization, dolomitization, kaolinization, minor sericitization, and silicification, are depleted in rare earth element. SEM-EDS evidence indicates that enrichment of rare earth element-bearing phosphates, such as monazite, occurred with carbonatization and kaolinization assemblages

87

Impurity trapped exciton states related to rare earth ions in crystals under high hydrostatic pressure  

International Nuclear Information System (INIS)

Emission related to rare earth ions in solids takes place usually due to 4fn ? 4fn and 4fn?15d1 ? 4fn internal transitions. In the case of band to band excitation the effective energy transfer from the host to optically active impurity is required. Among other processes one of the possibilities is capturing of the electron at excited state and hole at the ground state of impurity. Localization of electron or hole at the dopand site creates a long range Coulomb potential that attracts the second carrier which then occupies the localized Rydberg-like states. Such a system can be considered as impurity trapped exciton. Usually impurity trapped exciton is a short living phenomenon which decays non-radiatively leaving the impurity ion in the excited state. However, in several compounds doped with Eu2+ the impurity trapped exciton states become stable and contribute to the radiative processes though anomalous luminescence that appears apart of the 4f7 ? 4f7 and 4f75d1 ? 5f7 emission. In this contribution pressure effect on energies of the 4fn?15d1?5fn transitions in Ln doped oxides and fluorides as well as influence of pressure on the energy of impurity trapped exciton states is discussed. The latest results on high pressure investigations of luminescence related to Pr3+, and Eu2+ in dif, and Eu2+ in different lattices are reviewed.

88

Stress in highly demanding IT jobs: transformational leadership moderates the impact of time pressure on exhaustion and work-life balance.  

Science.gov (United States)

The objective of this article is to investigate transformational leadership as a potential moderator of the negative relationship of time pressure to work-life balance and of the positive relationship between time pressure and exhaustion. Recent research regards time pressure as a challenge stressor; while being positively related to motivation and performance, time pressure also increases employee strain and decreases well-being. Building on the Job Demand-Resources model, we hypothesize that transformational leadership moderates the relationships between time pressure and both employees' exhaustion and work-life balance such that both relationships will be weaker when transformational leadership is higher. Of seven information technology organizations in Germany, 262 employees participated in the study. Established scales for time pressure, transformational leadership, work-life balance, and exhaustion were used, all showing good internal consistencies. The results support our assumptions. Specifically, we find that under high transformational leadership the impact of time pressure on exhaustion and work-life balance was less strong. The results of this study suggest that, particularly under high time pressure, transformational leadership is an important factor for both employees' work-life balance and exhaustion. PMID:23834443

Syrek, Christine J; Apostel, Ella; Antoni, Conny H

2013-07-01

89

Validating and Calibrating the Nintendo Wii Balance Board to Derive Reliable Center of Pressure Measures  

Directory of Open Access Journals (Sweden)

Full Text Available The Nintendo Wii balance board (WBB has generated significant interest in its application as a postural control measurement device in both the clinical and (basic, clinical, and rehabilitation research domains. Although the WBB has been proposed as an alternative to the “gold standard” laboratory-grade force plate, additional research is necessary before the WBB can be considered a valid and reliable center of pressure (CoP measurement device. In this study, we used the WBB and a laboratory-grade AMTI force plate (AFP to simultaneously measure the CoP displacement of a controlled dynamic load, which has not been done before. A one-dimensional inverted pendulum was displaced at several different displacement angles and load heights to simulate a variety of postural sway amplitudes and frequencies (<1 Hz. Twelve WBBs were tested to address the issue of inter-device variability. There was a significant effect of sway amplitude, frequency, and direction on the WBB’s CoP measurement error, with an increase in error as both sway amplitude and frequency increased and a significantly greater error in the mediolateral (ML (compared to the anteroposterior (AP sway direction. There was no difference in error across the 12 WBB’s, supporting low inter-device variability. A linear calibration procedure was then implemented to correct the WBB’s CoP signals and reduce measurement error. There was a significant effect of calibration on the WBB’s CoP signal accuracy, with a significant reduction in CoP measurement error (quantified by root-mean-squared error from 2–6 mm (before calibration to 0.5–2 mm (after calibration. WBB-based CoP signal calibration also significantly reduced the percent error in derived (time-domain CoP sway measures, from ?10.5% (before calibration to ?0.05% (after calibration (percent errors averaged across all sway measures and in both sway directions. In this study, we characterized the WBB’s CoP measurement error under controlled, dynamic conditions and implemented a linear calibration procedure for WBB CoP signals that is recommended to reduce CoP measurement error and provide more reliable estimates of time-domain CoP measures. Despite our promising results, additional work is necessary to understand how our findings translate to the clinical and rehabilitation research domains. Once the WBB’s CoP measurement error is fully characterized in human postural sway (which differs from our simulated postural sway in both amplitude and frequency content, it may be used to measure CoP displacement in situations where lower accuracy and precision is acceptable.

Julia M. Leach

2014-09-01

90

Establishment of a force balanced piston gauge for very low gauge and absolute pressure measurements at NPL, India  

International Nuclear Information System (INIS)

National Physical Laboratory, the National Metrology Institute (NMI) of India is maintaining Primary standards of pressure that cover several decades of pressure, starting from 3.0E-06 Pa to 1.0 GPa. Among which a recent addition is a Force Balanced Piston Gauge, the non-rotating piston type, having better resolution and zero stability compared to any other primary pressure standards commercially available in the range 1.0 Pa to 15.0 kPa (abs and gauge). The characterization of this FPG is done against Ultrasonic Interferometer Manometer (UIM), the National Primary pressure standard, working in the range 1.0 Pa to 130.0 kPa (abs and diff) and Air Piston Gauge (APG), a Transfer Pressure Standard, working in the range 6.5 kPa to 360 kPa (abs and gauge), in their overlapping pressure regions covering both absolute and gauge pressures. As NPL being one of the signatories to the CIPM MRA, the Calibration and Measurement Capabilities (CMC) of both the reference standards (UIM and APG), are Peer reviewed and notified in the Key Comparison Data Base (KCDB) of BIPM. The estimated mean effective area of the Piston Cylinder assembly of this FPG against UIM (980.457 mm2) and APG (980.463 mm2) are well within 4 ppm and 10 ppm agreement respectively, with the manufacturer's reported value (980.453 mm2). The expanded uncertainty of this FPG, Q(0.012 Pa, 0.0025% of reading), evaluated against UIM as reference standard, is well within the reported valustandard, is well within the reported value of the manufacturer, Q(0.008 Pa, 0.003% of reading) at k = 2. The results of the characterization along with experimental setup and measurement conditions (for gauge and absolute pressure measurements), uncertainty budget preparation and evaluation of measurement uncertainty are discussed in detail in this paper.

91

Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand  

DEFF Research Database (Denmark)

The influence of wall flexibility on earth pressure, bending moments and failure modes is studied. Numerical models are compared to results from model tests carried out in a geotechnical centrifuge. The back-fill is dry sand and failure is introduced by allowing the wall to rotate around the anchor level. The Finite element program PLAXIS is used and two material models are evaluated, the Mohr-Coulomb model and the Hardening Soil model. The differences between the two concern the deformation properties. Generally good agreement was observed between physical and numerical models. The HS-model showed the right behaviour in pre-failure as well as failure for both flexible and stiff walls, whereas the MC-model showed some shortcomings when stiff walls were modelled.

KrogsbØll, Anette Susanne; Fuglsang, Leif D

2006-01-01

92

Direct solar and earth-albedo radiation pressure effects on the orbit of Pageos 1  

Science.gov (United States)

The orbit of the Pageos 1 balloon satellite was analyzed for the effects of direct solar and albedo radiation pressure. Anomalous behavior occurred in the orbital acceleration near the end of the 2nd year of the satellite's lifetime which may have resulted from the change in its shape; the shape has become slightly oblate, spinning about a minor axis and precessing about the direction of the sun. The near-earth micrometeoroid particle flux was estimated to be 5 x 10 to the -8th/sq cm/s by analyzing the balloon inflation process with sublimating compounds and the resulting variation of the satellite mass due to the leakage through the holes produced by micrometeoroid bombardment.

Zerbini, S.

1980-01-01

93

Structural stability and electronic structure of actinide and rare-earth based intermetallics under high pressure  

Science.gov (United States)

The rare-earth and actinide based intermetallics are endowed with exotic physical and chemical properties due to the presence of idiosyncratic f-electrons in these systems. These properties exhibit interesting changes under the action of various thermodynamic fields and hence continue to be a subject of extensive research. For instance, under pressure, the nature of f-electrons can be changed from localized to itinerant, leading to a variety of changes in their structural, physical and chemical properties. During the last one and half decade, we have carried out extensive research on the structural stability and phase transition behaviour of the aluminides and gallides of these f-electron based systems using a unique combination of Guinier diffractometer and diamond anvil cell. To bring out the correlations between the structural stability and phase transition behaviour with their electronic structure, we have also carried out electronic structure calculations as a function of reduced volume. In this talk, we have presented some of our studies on the AB2 type actinide and rare-earth based intermetallics, elaborated on the trends seen in the structural behaviour and correlated with their electronic structure.

Sahu, P. Ch; Shekar, N. V. Chandra

2010-03-01

94

Structural stability and electronic structure of actinide and rare-earth based intermetallics under high pressure  

Energy Technology Data Exchange (ETDEWEB)

The rare-earth and actinide based intermetallics are endowed with exotic physical and chemical properties due to the presence of idiosyncratic f-electrons in these systems. These properties exhibit interesting changes under the action of various thermodynamic fields and hence continue to be a subject of extensive research. For instance, under pressure, the nature of f-electrons can be changed from localized to itinerant, leading to a variety of changes in their structural, physical and chemical properties. During the last one and half decade, we have carried out extensive research on the structural stability and phase transition behaviour of the aluminides and gallides of these f-electron based systems using a unique combination of Guinier diffractometer and diamond anvil cell. To bring out the correlations between the structural stability and phase transition behaviour with their electronic structure, we have also carried out electronic structure calculations as a function of reduced volume. In this talk, we have presented some of our studies on the AB{sub 2} type actinide and rare-earth based intermetallics, elaborated on the trends seen in the structural behaviour and correlated with their electronic structure.

Sahu, P Ch; Shekar, N V Chandra, E-mail: pcsahu@igcar.gov.i [High Pressure Physics Section, Condensed Matter Physics Division Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

2010-03-01

95

A flow and pressure distribution of APR+ reactor under 4-pump running conditions with a balanced flow rate  

International Nuclear Information System (INIS)

In order to quantify the flow distribution characteristics of APR+ reactor, a test was performed on a test facility, ACOP (APR+ Core Flow and Pressure Test Facility), having a length scale of 1/5 referring to the prototype plant. The major parameters are core inlet flow and outlet pressure distribution and sectional pressure drops along the major flow path inside reactor vessel. To preserve the flow characteristics of prototype plant, the test facility was designed based on a preservation of major flow path geometry. An Euler number is considered as primary dimensionless parameter, which is conserved with a 1/40.9 of Reynolds number scaling ratio. ACOP simplifies each fuel assembly into a hydraulic simulator having the same axial flow resistance and lateral cross flow characteristics. In order to supply boundary condition to estimate thermal margins of the reactor, the distribution of inlet core flow and core exit pressure were measured in each of 257 fuel assembly simulators. In total, 584 points of static pressure and differential pressures were measured with a limited number of differential pressure transmitters by developing a sequential operation system of valves. In the current study, reactor flow characteristics under the balanced four cold leg flow conditions at each of the cold legs were quantified, which is a part of the test matrix composing the APR+ flow distribution test program. The final identification of the reactor flow distribution was obtained by enactor flow distribution was obtained by ensemble averaging 15 independent test data. The details of the design of the test facility, experiment, and data analysis are included in the current paper.

96

Study on passive earth pressure acting on the embedment of an earth retaining wall for braced excavation work in cohesive soil; Nenseido jiban ni okeru kussaku dodomeheki neirebu no judo doatsu ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

Passive earth pressure exerts a great influence on the stress and deformation of earth retaining walls in braced excavation. To calculate this pressure, conventional ultimate earth pressure equation, or Rankine-Resals and Coulomb`s equation, are currently applied respectively to cohesive and sandy soil. However, these intentional equation to determine passive earth pressure do not adequately take into account the excavation width during work and the shearing resistance on the earth retaining wall surface. This paper deals with cohesive soil only, deriving a calculation equation for passive earth pressure, which takes into account excavation width and the shearing resistance of the earth retaining wall surface. Then, constants in this equation are determined using the calculation results obtained from the finite element method with blasts-plastic elements. The calculation results are also compared with measured values in the model test in order to check the applicability of the calculation equation for passive earth pressure thus obtained. Finally, this paper proposes a practicable calculation equation for passive earth pressure. 13 refs., 10 figs., 10 tabs.

Nakamura, H. [Pacific Consultants K.K., Tokyo (Japan); Hirashima, K. [Yamanashi University, Yamanashi (Japan). Faculty of Engineering

1995-12-15

97

Barometric pressure, dry bulb temperature and vapor pressure at the lowest terrestrial site on earth, Dead Sea basin, Neve Zohar, Israel  

Science.gov (United States)

The Dead Sea basin is located at the lowest terrestrial site on the earth and, thereby, has the tallest atmospheric air column above its surface. Consequently, the Dead Sea basin is expected, a priori, to have the highest terrestrial barometric pressure and, thereby, the highest molecular oxygen density on the earth. The barometric pressure and dry bulb temperature have been monitored continuously at Neve Zohar, located on the western shore of the Dead Sea, since January 1995. The monthly average daily barometric pressure values exceed normal atmospheric pressure by a maximum of 4.83 hPa (4.77%) and a minimum of 33.1 hPa (3.26%) for December and July, respectively. This increase in barometric pressure can serve as a simple way to improve arterial oxygenation in hypoxemic patients. As a result, a number of research projects have been initiated on the treatment of patients suffering from pulmonary and cardiac diseases at the Dead Sea basin. The hourly barometric pressure data with regard to both its diurnal and monthly variation and the correlation between barometric pressure and dry bulb temperature will be analyzed.

Kudish, A. I.; Evseev, E. G.

2006-03-01

98

Vapor pressure and activity of components of melts formed by manganese chloride and chlorides of alkaline-earth metals  

International Nuclear Information System (INIS)

The boiling points of melts were measured at different pressures over the melts for certain concentrations of components of the liquid phase in binary systems constituted by manganese chloride and chlorides of alkaline-earth metals. The temperature dependences of the saturated vapor pressure, normal boiling points, and enthalpies of evaporation were calculated. The concentration dependences of the thermodynamic activities of the components of four binary systems MnCl2-MCl2 (M=Mg, Ca, Sr, Ba) were analyzed

99

Unusual pressure dependence of the crystallographic structure in RNiO{sub 3} perovskites (R = rare earth)  

Energy Technology Data Exchange (ETDEWEB)

We report the first experimental observation of a pressure-induced structural phase transition in the RNiO{sub 3} series (R = rare earth). At {approx_equal} 40 kbar, the space group of NdNiO{sub 3} changes from Pbnm(orthorhombic) to the PrNiO{sub 3} indicating that the symmetry of the structure increases with pressure. (author) 1 fig., 7 refs.

Medarde, M.; Mesot, J.; Rosenkranz, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Lacorre, P. [Lab. Fluorures, Le Mans (France); Marshall, W.; Loveday, J.S. [Edinburgh Univ. (United Kingdom); Klotz, S.; Hamel, G. [Paris-6 Univ., 75 (France)

1997-09-01

100

Laterality of lower limbs and relationship with the plantar pressure distribution in the static balance  

Directory of Open Access Journals (Sweden)

Full Text Available The distribution of loads during gait has been evaluated in many studies, some of which have been seen to influence the handedness of the individual in this distribution. However, in the static pool, several studies have been carried out which assess the possible causes of inequitable distribution of the charges, some according to the vision or adjoining space and according to influence of visual laterality. In our study we will observe the influence of the lateral lower limb preference in the distribution of the load on the sole of the foot, using three tests to assess the lateral dominance: shoot with precision, dynamic balance and static balance (Maupas et al. 2002. According to our results, lower limb lateral preference does not influence significantly the distribution of charges in the sole of the foot, however, we observe a tendency to increase the load/weight on the left limb in righthanded people (according to tests of balance dynamic and precision shot and on the right limb in left handed people

*Carmen Mayolas Pi*, Adoración Villarroya Aparicio*, Joaquín Reverter Masia**

2011-06-01

 
 
 
 
101

Argon surface wave discharges at medium pressure. Experiments and discussion on the energy balance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Argon surface wave discharges, created at 210 MHz in capillary tubes have been studied at medium pressure, from 10 Torr to 200 Torr. Such discharges have been experimentally characterized ; the electron density profile along the plasma column, the effective electron neutral collision frequency v and the mean power needed to maintain an electron-ion pair in the discharge 0 have been determined as functions of the pressure. It is experimentally proven that 0 is independent of the electron densi...

Granier, A.; Gousset, G.; Leprince, P.; Marec, J.

1987-01-01

102

Potassium Modulates Electrolyte Balance and Blood Pressure through Effects on Distal Cell Voltage and Chloride.  

Science.gov (United States)

Dietary potassium deficiency, common in modern diets, raises blood pressure and enhances salt sensitivity. Potassium homeostasis requires a molecular switch in the distal convoluted tubule (DCT), which fails in familial hyperkalemic hypertension (pseudohypoaldosteronism type 2), activating the thiazide-sensitive NaCl cotransporter, NCC. Here, we show that dietary potassium deficiency activates NCC, even in the setting of high salt intake, thereby causing sodium retention and a rise in blood pressure. The effect is dependent on plasma potassium, which modulates DCT cell membrane voltage and, in turn, intracellular chloride. Low intracellular chloride stimulates WNK kinases to activate NCC, limiting potassium losses, even at the expense of increased blood pressure. These data show that DCT cells, like adrenal cells, sense potassium via membrane voltage. In the DCT, hyperpolarization activates NCC via WNK kinases, whereas in the adrenal gland, it inhibits aldosterone secretion. These effects work in concert to maintain potassium homeostasis. PMID:25565204

Terker, Andrew S; Zhang, Chong; McCormick, James A; Lazelle, Rebecca A; Zhang, Chengbiao; Meermeier, Nicholas P; Siler, Dominic A; Park, Hae J; Fu, Yi; Cohen, David M; Weinstein, Alan M; Wang, Wen-Hui; Yang, Chao-Ling; Ellison, David H

2015-01-01

103

Pressure sensor-based tongue-placed electrotactile biofeedback for balance improvement - Biomedical application to prevent pressure sores formation and falls  

CERN Document Server

We introduce the innovative technologies, based on the concept of "sensory substitution", we are developing in the fields of biomedical engineering and human disability. Precisely, our goal is to design, develop and validate practical assistive biomedical and/or technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in case of spinal cord injuries (persons with paraplegia, or tetraplegia); and (2) balance control improvement to prevent fall in older and/or disabled adults. This paper describes the architecture and the functioning principle of these biofeedback systems and presents preliminary results of two feasibility studies performed on young healthy adults.

Vuillerme, Nicolas; Pinsault, Nicolas; Moreau-Gaudry, Alexandre; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

2007-01-01

104

Pressure sensor-based tongue-placed electrotactile biofeedback for balance improvement--biomedical application to prevent pressure sores formation and falls.  

Science.gov (United States)

We introduce the innovative technologies, based on the concept of "sensory substitution", we are developing in the fields of biomedical engineering and human disability. Precisely, our goal is to design, develop and validate practical assistive biomedical and/or technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in case of spinal cord injuries (persons with paraplegia, or tetraplegia); and (2) balance control improvement to prevent fall in older and/or disabled adults. This paper describes the architecture and the functioning principle of these biofeedback systems and presents preliminary results of two feasibility studies performed on young healthy adults. PMID:18003410

Vuillerme, N; Chenu, O; Pinsault, N; Moreau-Gaudry, A; Fleury, A; Demongeot, J; Payan, Y

2007-01-01

105

South Dakota Space Grant Consortium: Balancing Indigenous Earth System and Space Science with Western/Contemporary Science  

Science.gov (United States)

The South Dakota Space Grant Consortium (SDSGC) was established March 1, 1991 by a NASA Capability Enhancement Grant. Since that time SDSGC has worked to provide earth system and space science education, outreach and services to all students across South Dakota. South Dakota has nine tribes and five Tribal Colleges. This has presented a tremendous opportunity to develop sustainable equitable partnerships and collaborations. SDSGC believes strongly in developing programs and activities that highlight and reinforce the balance of Indigenous science and ways of knowing with current findings in Western/Contemporary Science. This blending of science and culture creates a learning community where individuals especially students, can gain confidence and pride in their unique skills and abilities. Universities are also witnessing the accomplishments and achievements of students who are able to experience a tribal environment and then carry that experience to a college/university/workplace and significantly increase the learning achievement of all. The presentation will highlight current Tribal College and Tribal Community partnerships with the Rosebud Sioux Reservation (Sinte Gleska University), Pine Ridge Indian Reservation (Oglala Lakota College), Standing Rock Sioux Reservation (Sitting Bull College) and Cheyenne River Sioux Reservation (Si Tanka) amongst others. Programs and activities to be explained during the presentation include but not limited to: NASA Workforce Native Connections, Scientific Knowledge for Indian Learning and Leadership (SKILL), NSF "Bridges to Success" Summer Research Program, NSF "Fire Ecology" Summer Research Experience, as well as geospatial and space science programs for students and general community members. The presentation will also cover the current initiatives underway through NASA Workforce Development. These include: partnering with the Annual He Sapa Wacipi (Black Hills Pow Wow - attendance of 14,000 Natives) to host Native Space Days 2005 (October 2005), NASA research and internship programs, and the NASA Student Fellowship Summit. An overview of recent American Indian student success will conclude the presentation. The South Dakota School of Mines and Technology has struggled over many years to develop and implement sustainable successful initiatives with Tribal Colleges and Communities. The motivating philosophy is the betterment of all people in South Dakota and the nation through developing a worldview and understanding of the integrated nature of all things, especially earth system and space science. If people are provided equity and access, there is no limit to what they can accomplish. SDSM&T in the last three years has graduated nineteen Natives with degrees in engineering, many of those students Tribal College transfers. This is a significant increase, as only forty Natives had graduated from SDSM&T between the years of 1970 and 2000. SDSM&T has seen a number of "historical firsts" in the past five years. We see this as being a direct result of creating for students an educational philosophy and process where Indigenous understanding and connections become the foundation on which to build a STEM degree program. NASA's presence on the SDSM&T campus and in South Dakota has provided the necessary focus and encouragement for success to take place. We are building bridges in South Dakota and the builders are from Indian Country.

Bolman, J.; Nall, J.

2005-05-01

106

Earth'  

...  Examples of overshooting include cutting down trees more quickly than they can re-grow, catching fish at a faster rate than they reproduce and releasing more CO2 into the atmosphere than the planet can absorb. First overshoot in 1986  While overshooting is manageable for a short while, repeated overshoots deplete the resources upon which our economy depends and add to the Earth's 'ecological debt'. According to the Global Footprint Network, humanity first went into overshoot ...

107

Azimuthal Pressure Gradient and Associated Auroral Development in the Near-Earth Plasma Sheet Soon Before Substorm Onset  

Science.gov (United States)

The azimuthal plasma pressure gradient in the near-Earth plasma sheet makes crucial contributions to field-aligned current (FAC) formation. Numerical simulations and statistical observations have shown that a plasma pressure peak tends to build up in the pre-midnight region of the near-earth plasma sheet during the substorm growth phase due to enhanced magnetic drift. This leads to azimuthal pressure gradients in this region. The temporal variation of the azimuthal pressure gradient may provide an indication for the FACs variations associated with the substorm growth phase and thus may setup a plasma sheet pre-condition for the substorm onset being triggered near this region. We take advantage of two of the THEMIS spacecraft separated azimuthally near the orbit apogee and investigate the azimuthal plasma pressure gradient in the R~10-12 RE region. Equatorial plasma pressure is estimated by removing the curvature force effect. Four events with the spacecraft footprints mapped very close to the aurora onset region were selected. Two of them showed substantial duskward pressure gradient enhancement 2-5 min before onset. A late-growth-phase auroral arc, which became the substorm onset arc, was found to intensify simultaneously with the pressure gradient enhancement. The other two vents showed almost no change of azimuthal pressure gradient before onset, at the same time neither growth-phase auroral arc intensification was found near the spacecraft footprints, nor did onset occur along an observable arc. These results indicate that the duskward azimuthal pressure gradient enhancement associated with enhanced upward FACs during the late-growth-phase may provide important energy redistribution for the intensification of the growth-phase auroral arc soon before it breaks up and set up conditions for substorm onset to occur along such an arc.

Xing, X.; Lyons, L. R.; Nishimura, Y.; Angelopoulos, V.; Donovan, E. F.; Larson, D. E.; Carlson, C. W.; Auster, H.

2010-12-01

108

Soft-tissue balancing with pressure distribution during total knee arthroplasty.  

Science.gov (United States)

We measured the pressure distribution across the tibiofemoral and patellofemoral joints during total knee arthroplasty (TKA) using Fuji pressure-sensitive film (Prescale) in 51 patients (63 joints) comparing the results with those in 21 patients in whom Prescale was not used. We classified the stress-distribution patterns in the tibiofemoral joints into four types: normal, varus-valgus instability, rotational malalignment, and a combination of instability and malrotation. The medial ligaments were then released according to the information obtained from these patterns. The conformity ratio of the contact area between repeated trials was 87.0%. Pressure distribution across the patellofemoral joints was also considered. There was a significant decrease in the mean valgus stress angle in the Prescale group compared with the control group (p < 0.01). Release of the lateral retinaculum according to the results showed no significant differences in subluxation of the patella between the released group and the group which did not appear to need this procedure. PMID:9119849

Takahashi, T; Wada, Y; Yamamoto, H

1997-03-01

109

Exposure of phototrophs to 548 days in low Earth orbit: microbial selection pressures in outer space and on early earth  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated wi...

Cockell, Charles S.; Rettberg, Petra; Rabbow, Elke; Olsson-francis, Karen

2011-01-01

110

In-situ response time testing of force-balance pressure transmitters in nuclear power plants  

International Nuclear Information System (INIS)

This paper reports on recommendations for response time testing of safety system pressure transmitters in nuclear power plants that are found in Regulatory Guide 1.118 and requirements are defined in plant technical specifications. The conventional testing method involves simultaneously applying a pressure ramp signal to the process transmitter and to a fast-response reference transmitter. The time delay between the response of the two transmitters, when they obtain a predetermined value, is called the process transmitter response time. This method is referred to as the ramp test. Although the ramp test is an accepted method, large variations in its results are sometimes encountered because of empirical difficulties associated with the test. This test requires access to each transmitter, and it must be performed inside the containment during shutdown. The in-situ test is accomplished by interrupting the power to the transmitter for a few seconds. It is referred to as the Power Interrupt (PI) test, and it can be conducted while the plant is operating. The test includes the entire electromechanical system and the response time is obtained by analyzing the transient response following the restoration of power to the transmitter. Response times obtained from the PI test and the ramp test are in good agreement and usually differ by less than 50 ms

111

Small Scale Pressure-Balanced Structures Driven by Slow-mode Waves in the Solar Wind  

Science.gov (United States)

This work aims to reveal the dependence of the properties of small-scale PBSs on the background magnetic field (B0) direction and thus to corroborate the in situ mechanism that forms them. We analyze the plasma and magnetic field data obtained by WIND in the quiet fast solar wind at 1 AU. By wavelet cross-coherence analysis, we obtain the correlation coefficients and phase angle between the thermal pressure Pth and the magnetic pressure PB, distributing against the temporal scale and the angle ?xB between B0 and GSE-x. We note that the angle coverage of a PBS decreases with shorter temporal scale, but the occurrence of the PBSs is independent of ?xB. Suspecting that the isolated small PBSs are formed by compressive waves in situ, we continue this study by testing the wave mode forming a small-scale PBS with B0 quasi-parallel to GSE-x. We use the proton velocity distribution functions to reveal the proton temperature anisotropy T? /T?. Besides, minimum variance analysis is applied to find the magnetic field minimum variance vector BN as wave vector k. We also study the time variation of the cross-helicity sigma_c and compressibility Cp, and compare with that from the numerical predictions for slow-mode waves. Finally, short time small-scale PBS is proved to be driven by oblique slow-mode waves in the solar wind.

Yao, S.; Tu, C.; He, J.; Wang, L.; Marsch, E.

2013-12-01

112

Pressure Balance at Mars and Solar Wind Interaction with the Martian Atmosphere  

Science.gov (United States)

The strongest crustal fields are located in certain regions in the Southern hemisphere. In the Northern hemisphere, the crustal fields are rather weak and usually do not prevent direct interaction between the SW and the Martian ionosphere/atmosphere. Exceptions occur in the isolated mini-magnetospheres formed by the crustal anomalies. Electron density profiles of the ionosphere of Mars derived from radio occultation data obtained by the Radio Science Mars Global Surveyor (MGS) experiment have been compared with the crustal magnetic fields measured by the MGS Magnetometer/Electron Reflectometer (MAG/ER) experiment. A study of 523 electron density profiles obtained at latitudes from +67 deg. to +77 deg. has been conducted. The effective scale-height of the electron density for two altitude ranges, 145-165 km and 165-185 km, and the effective scale-height of the neutral atmosphere density in the vicinity of the ionization peak have been derived for each of the profiles studied. For the regions outside of the potential mini-magnetospheres, the thermal pressure of the ionospheric plasma for the altitude range 145-185 km has been estimated. In the high latitude ionosphere at Mars, the total pressure at altitudes 160 and 180 km has been mapped. The solar wind interaction with the ionosphere of Mars and origin of the sharp drop of the electron density at the altitudes 200-210 km will be discussed.

Krymskii, A. M.; Ness, N. F.; Crider, D. H.; Breus, T. K.; Acuna, M. H.; Hinson, D.

2003-01-01

113

Chaotic behavior of water column oscillator simulating pressure balanced injection system in passive safety reactor  

Energy Technology Data Exchange (ETDEWEB)

Japan Atomic Energy Research Institute (JAERI) proposed a passive safety reactor called the System-integrated Pressurized Water Reactor (SPWR). In a loss of coolant accident, the Pressurizing Line (PL) and the Injection Line (IL) are passively opened. Vapor generated by residual heat pushes down the water level in the Reactor Vessel (RV). When the level is lower than the inlet of the PL, the vapor is ejected into the Containment Vessel (CV) through the PL. Then boronized water in the CV is injected into the RV through the IL by the static head. In an experiment using a simple apparatus, gas ejection and water injection were found to occur alternately under certain conditions. The gas ejection interval was observed to fluctuate considerably. Though stochastic noise affected the interval, the experimental results suggested that the large fluctuation was produced by an inherent character in the system. A set of piecewise linear differential equations was derived to describe the experimental result. The large fluctuation was reproduced in the analytical solution. Thus it was shown to occur even in a deterministic system without any source of stochastic noise. Though the derived equations simulated the experiment well, they had ten independent parameters governing the behavior of the solution. There appeared chaotic features and bifurcation, but the analytical model was too complicated to examine the features and mechanism of bifurcation. In this study, a new simple model is proposed which consists of a set of piecewise linear ordinary differential equations with only four independent parameters. (authors)

Morimoto, Y.; Madarame, H.; Okamoto, K. [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

2001-07-01

114

Super earth interiors and validity of Birch's Law for ultra-high pressure metals and ionic solids  

Science.gov (United States)

Super Earths, recently detected by the Kepler Mission, expand the ensemble of known terrestrial planets beyond our Solar System's limited group. Birch's Law and velocity-density systematics have been crucial in constraining our knowledge of the composition of Earth's mantle and core. Recently published static diamond anvil cell experimental measurements of sound velocities in iron, a key deep element in most super Earth models, are inconsistent with each other with regard to the validity of Birch's Law. We examine the range of validity of Birch's Law for several metallic elements, including iron, and ionic solids shocked with a two-stage light gas gun into the ultra-high pressure, temperature fluid state and make comparisons to the recent static data.

Ware, Lucas Andrew

2015-01-01

115

The “Stick-Slip” Phenomenon During the Active Earth Pressure Failure of a Granular Soil of Analogical Material  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this paper is to highlight the "stick-slip" phenomenon in the mechanisms of failure related to active earth pressure of an analogical material simulating a granular medium. For this, a two-dimensional small-scale model was used and a phenomenological analysis of these mechanisms was conducted employing measurements of the fields of deformations using the method of digital image correlation. It was noted that a fluctuation in the response of the material occurs during the equal increments of displacements imposed on the mobile wall. This incremental response of the medium during the failure process related to active earth pressure explains the "stick-slip" phenomenon

S. M. Daoud

2014-02-01

116

Engineering kinematic theory of the contact earth pressure and its application to the static calculation of thin quay walls  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Construction of deep-water thrust berthing structures requires using new and more perfect methods of calculation containing fewer assumptions. A version of the engineering kinematic theory of contact earth pressure in the application to the water-transport and offshore structures was suggested in the article. A dimensionless static “compression – tension” diagram of the soil, presented by curvilinear function, was used in the method. In this case, the displacement of the limit point of ...

Korovkin, V. S.

2013-01-01

117

Small-scale Pressure-balanced Structures Driven by Oblique Slow Mode Waves Measured in the Solar Wind  

Science.gov (United States)

Recently, small-scale pressure-balanced structures (PBSs) were identified in the solar wind, but their formation mechanism remains unclear. This work aims to reveal the dependence of the properties of small-scale PBSs on the background magnetic field (B 0) direction and thus to corroborate the in situ mechanism that forms them. We analyze the plasma and magnetic field data obtained by WIND in the quiet solar wind at 1 AU. First, we use a developed moving-average method to obtain B 0(s, t) for every temporal scale (s) at each time moment (t). By wavelet cross-coherence analysis, we obtain the correlation coefficients between the thermal pressure P th and the magnetic pressure P B, distributing against the temporal scale and the angle ?xB between B 0(s, t) and Geocentric Solar Ecliptic coordinates (GSE)-x. We note that the angle coverage of a PBS decreases with shorter temporal scale, but the occurrence of the PBSs is independent of ?xB. Suspecting that the isolated small PBSs are formed by compressive waves in situ, we continue this study by testing the wave modes forming a small-scale PBS with B 0(s, t) quasi-parallel to GSE-x. As a result, we identify that the cross-helicity and the compressibility attain values for a slow mode from theoretical calculations. The wave vector is derived from minimum variance analysis. Besides, the proton temperatures obey T < T ? derived from the velocity distribution functions, excluding a mirror mode, which is the other candidate for the formation of PBSs in situ. Thus, a small-scale PBS is shown to be driven by oblique, slow-mode waves in the solar wind.

Yao, Shuo; He, J.-S.; Tu, C.-Y.; Wang, L.-H.; Marsch, E.

2013-09-01

118

Small-scale Pressure-balanced Structures Driven by Mirror-mode Waves in the Solar Wind  

Science.gov (United States)

Recently, small-scale pressure-balanced structures (PBSs) have been studied with regard to their dependence on the direction of the local mean magnetic field B0 . The present work continues these studies by investigating the compressive wave mode forming small PBSs, here for B0 quasi-perpendicular to the x-axis of Geocentric Solar Ecliptic coordinates (GSE-x). All the data used were measured by WIND in the quiet solar wind. From the distribution of PBSs on the plane determined by the temporal scale and angle ?xB between the GSE-x and B0 , we notice that at ?xB = 115° the PBSs appear at temporal scales ranging from 700 s to 60 s. In the corresponding temporal segment, the correlations between the plasma thermal pressure P th and the magnetic pressure P B, as well as that between the proton density N p and the magnetic field strength B, are investigated. In addition, we use the proton velocity distribution functions to calculate the proton temperatures T and T ?. Minimum Variance Analysis is applied to find the magnetic field minimum variance vector BN . We also study the time variation of the cross-helicity ?c and the compressibility C p and compare these with values from numerical predictions for the mirror mode. In this way, we finally identify a short segment that has T > T ?, proton ? ~= 1, both pairs of P th-P B and N p-B showing anti-correlation, and ?c ? 0 with C p > 0. Although the examination of ?c and C p is not conclusive, it provides helpful additional information for the wave mode identification. Additionally, BN is found to be highly oblique to B0 . Thus, this work suggests that a candidate mechanism for forming small-scale PBSs in the quiet solar wind is due to mirror-mode waves.

Yao, Shuo; He, J.-S.; Tu, C.-Y.; Wang, L.-H.; Marsch, E.

2013-10-01

119

SMALL-SCALE PRESSURE-BALANCED STRUCTURES DRIVEN BY OBLIQUE SLOW MODE WAVES MEASURED IN THE SOLAR WIND  

Energy Technology Data Exchange (ETDEWEB)

Recently, small-scale pressure-balanced structures (PBSs) were identified in the solar wind, but their formation mechanism remains unclear. This work aims to reveal the dependence of the properties of small-scale PBSs on the background magnetic field (B{sub 0}) direction and thus to corroborate the in situ mechanism that forms them. We analyze the plasma and magnetic field data obtained by WIND in the quiet solar wind at 1 AU. First, we use a developed moving-average method to obtain B{sub 0}(s, t) for every temporal scale (s) at each time moment (t). By wavelet cross-coherence analysis, we obtain the correlation coefficients between the thermal pressure P{sub th} and the magnetic pressure P{sub B}, distributing against the temporal scale and the angle {theta}{sub xB} between B{sub 0}(s, t) and Geocentric Solar Ecliptic coordinates (GSE)-x. We note that the angle coverage of a PBS decreases with shorter temporal scale, but the occurrence of the PBSs is independent of {theta}{sub xB}. Suspecting that the isolated small PBSs are formed by compressive waves in situ, we continue this study by testing the wave modes forming a small-scale PBS with B{sub 0}(s, t) quasi-parallel to GSE-x. As a result, we identify that the cross-helicity and the compressibility attain values for a slow mode from theoretical calculations. The wave vector is derived from minimum variance analysis. Besides, the proton temperatures obey T < T{sub Parallel-To} derived from the velocity distribution functions, excluding a mirror mode, which is the other candidate for the formation of PBSs in situ. Thus, a small-scale PBS is shown to be driven by oblique, slow-mode waves in the solar wind.

Yao Shuo [School of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing 100083 (China); He, J.-S.; Tu, C.-Y.; Wang, L.-H. [Department of Geophysics, Peking University, Beijing (China); Marsch, E., E-mail: yaoshuo@cugb.edu.cn [Christian Albrechts University at Kiel, Kiel (Germany)

2013-09-01

120

SMALL-SCALE PRESSURE-BALANCED STRUCTURES DRIVEN BY MIRROR-MODE WAVES IN THE SOLAR WIND  

International Nuclear Information System (INIS)

Recently, small-scale pressure-balanced structures (PBSs) have been studied with regard to their dependence on the direction of the local mean magnetic field B0 . The present work continues these studies by investigating the compressive wave mode forming small PBSs, here for B0 quasi-perpendicular to the x-axis of Geocentric Solar Ecliptic coordinates (GSE-x). All the data used were measured by WIND in the quiet solar wind. From the distribution of PBSs on the plane determined by the temporal scale and angle ?xB between the GSE-x and B0 , we notice that at ?xB = 115° the PBSs appear at temporal scales ranging from 700 s to 60 s. In the corresponding temporal segment, the correlations between the plasma thermal pressure Pth and the magnetic pressure PB, as well as that between the proton density Np and the magnetic field strength B, are investigated. In addition, we use the proton velocity distribution functions to calculate the proton temperatures T and T?. Minimum Variance Analysis is applied to find the magnetic field minimum variance vector BN . We also study the time variation of the cross-helicity ?c and the compressibility Cp and compare these with values from numerical predictions for the mirror mode. In this way, we finally identify a short segment that has T > T?, proton ? ? 1, both pairs of Pth-PB and Np-B showing anti-correlation, and ?c ? 0 with Cp > 0. Although the examination of ?c and Cp is not conclusive, it provides helpful additional information for the wave mode identification. Additionally, BN is found to be highly oblique to B0 . Thus, this work suggests that a candidate mechanism for forming small-scale PBSs in the quiet solar wind is due to mirror-mode waves

 
 
 
 
121

The effect of different skin-ankle brace application pressures on quiet single-limb balance and electromyographic activation onset of lower limb muscles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG) activation sequence of four lower limb muscles. Metho...

Papadakis Stamatios A; Vagenas George; Badekas Athanasios; Nikolopoulos Christos; Papadopoulos Emmanuel S; Athanasopoulos Spyros

2007-01-01

122

The effect of different skin-ankle brace application pressures on quiet single-limb balance and electromyographic activation onset of lower limb muscles  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG activation sequence of four lower limb muscles. Methods Thirty three male physical education students who volunteered to take part in the study were measured under three ankle brace conditions: i without brace, ii with brace and 30 kPa application pressure and iii with brace and 60 kPa application pressure. Single limb balance (anteroposterior and mediolateral parameter was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris activation onset. Results The results showed that overall balance (total stability parameter was not significantly affected in any of the three ankle brace conditions. However, the anteroposterior centre of pressure excursion and centre of pressure excursion velocity were significantly increased with the application of ankle brace, both with 30 and 60 kPa application pressures. Furthermore, it was found that single limb balance was significantly worse with closed eyes compared to open eyes. EMG measurements showed that the sequence of lower limb activation onset was not affected in any of the three ankle brace application conditions. The results of this study showed that the application of an ankle brace with two different skin-brace interface pressures had no effect on overall single limb balance and the sequence of lower limb muscle activation. Conclusion These findings suggest that peripheral joint receptors are either not adequately stimulated by the brace application and therefore are not able to alter the balance control strategy of the CNS, or that they play a less important role in the control of single limb balance. Further research is needed in this area with more dynamic and functional measurements, before the safe use of ankle bracing can be widely recommended.

Papadakis Stamatios A

2007-09-01

123

Heliotropic orbits at oblate asteroids: balancing solar radiation pressure and J2 perturbations  

Science.gov (United States)

The combined effect of significant solar radiation pressure and perturbations on spacecraft orbits is investigated using both singly and doubly-averaged disturbing potentials with the Lagrange Planetary Equations. The resulting dynamics are applied to a spacecraft around an oblate asteroid. Several Sun-frozen families of orbits are identified using the singly-averaged potential, including two new families of orbits and a previously-discovered equatorial heliotropic orbit family. Families of both stable and unstable Sun-frozen orbits are mapped and characterized in the singly-averaged case. In addition, a heliotropic constraint is implemented to locate heliotropic orbits out of the equatorial plane using a constrained, doubly-averaged potential. Dynamic bounds for these 3D heliotropic orbits are shown to have an inclination limit of approximately 46 degrees for oblate bodies, and this limit is independent of the value of and radiation parameters. The resulting heliotropic and related periodic families of orbits are good candidates to consider for low-altitude science orbits around small oblate bodies with low or near-180 degree obliquity like Bennu, the target for the OSIRIS-REx mission.

Lantukh, Demyan; Russell, Ryan P.; Broschart, Stephen

2015-02-01

124

Pressure and Ionization Balances in the Circum-Heliospheric Interstellar Medium and the Local Bubble  

CERN Document Server

A disconcerting mismatch of thermal pressures for two media in contact with each other, (1) the warm, Circum-heliospheric Interstellar Medium (CHISM) and (2) the very hot material within a much larger region called the Local Bubble (LB), has troubled astronomers for over two decades. A possible resolution of this problem, at least in part, now seems possible. We now understand that earlier estimates for the average electron density in the very hot LB plasma were inflated by an unrecognized foreground contamination to the low energy diffuse X-ray background measurements. This foreground illumination arises from photons emitted by charge exchange reactions between solar wind ions and neutral atoms from the interstellar medium that enter into the heliosphere. However, with the resolution of this problem comes a new one. The high ionization fraction of helium in the CHISM, relative to that of hydrogen, could be understood in terms of the effects from a strong flux of EUV and X-ray radiation coming from both the L...

Jenkins, Edward B

2008-01-01

125

In-situ Laser Heating and Pressure Change With Radial Diffraction to Investigate Deformation of Deep Earth Relevant Minerals  

Science.gov (United States)

: Many deep Earth mineral phases have stability fields that are accessible only with diamond anvil cell (DAC), and currently this remains the only method for studying these mineral phases at pressures relevant to the deep Earth. So far radial diffraction DAC experiments have had two serious limitations, pressure and stress could only be applied incrementally ex-situ and deformation was limited to ambient temperature. These limitations bring into question the applicability of these experiments to deformation behavior in the deep earth where minerals are deforming at high-temperature and pressure. To address this issue we developed a novel combination of remotely controlled radial DAC with in-situ laser heating. This enables us to change pressure and thus stress on the sample while at high temperature. For remotely controlling the pressure we constructed a holding frame which can be used for different radial cell designs. The DAC is placed within the holding frame together with a gas-driven membrane. Inflating the membrane pushes the piston into the cylinder which is retained by the frame. While the membrane applies force from the bottom, the top of the assembly provides optical access for one- sided laser heating. The laser is directed from the top, vertically along the symmetry axis of the DAC onto the sample. The gas-pressure can be controlled remotely from outside the hutch, thus allowing for pressure change during heating and X-ray exposure. Using in-situ laser heating we induce recrystallization in a sample of Mg0.75Fe0.25O that had been deformed at room temperature. We observe grain growth and texture strengthening upon recrystallization. The remote pressure control is used to deform bcc Fe into the hcp Fe stability field and then back into the bcc phase on decompression. We observe development of strong textures in both the bcc phase and the hcp phase of Fe as well as texture change during decompression of the hcp phase. By combining the techniques, we convert in-situ a sample of natural San Carlos olivine (Fo90.7Fa9.3) into an assemblage of perovskite and periclase in the DAC. This sample was deformed at pressures from 30 to 50 GPa and at a temperature of 1100 ± 100 K. Both perovskite and periclase develop texture during deformation with periclase developing the stronger texture of the two. Texture in periclase is different from that obtained in room temperature compression experiments and this could be due to deformation in a two phase aggregate or deformation at high temperature. Elastic lattice strains are significantly lower in the perovskite and periclase assemblage when deformed at high temperature as compared to a room temperature experiment.

Miyagi, L.; Kunz, M.; Voltolini, M.; Wenk, H.

2007-12-01

126

Energy balance in a low pressure capacitive discharge driven by a double-saddle antenna  

International Nuclear Information System (INIS)

A radio frequency (rf) plasma is created at low pressure (?1 mTorr) in the source tube of a 'helicon' excited diffusion system in the absence of a dc magnetic field. The coupling is capacitive for the low source power of 160 W at 13.56 MHz considered here. Temperature measurements of the glass source tube yield a plasma power deposition of ?35 W. The plasma parameters (density, potential, electron temperature) were measured using a retarding field energy analyzer. An analytical model based on the measured plasma parameters and on additional external parameters measured in the matching box (rf voltages and phase, rf current) is developed. The model takes into account the geometry of the double saddle rf antenna. It is found that the inside of the glass wall adjacent to the antenna wire charges negatively. Ion acceleration into the glass along the antenna and fast electrons escaping the plasma account for most of the power deposition to the walls (?16.8 W). Secondary electrons liberated by ions impinging onto the glass along the antenna contribute a power of ?4.6 W. Adding the power of 3.7 W deposited to the part of the tube not affected by the antenna, the total power deposition responsible for the temperature rise of the tube is found to be about 25 W. The model shows that the power deposition is strongly nonuniform along the tube as a result of the antenna geometry. An estimate of the power deposited into the electrons by stochastic heating yields ?1.4 W, cchastic heating yields ?1.4 W, compared to an estimate of 5.8 W for the measured power loss from electrons

127

Extrarenal Na+ balance, volume, and blood pressure homeostasis in intact and ovariectomized deoxycorticosterone-acetate salt rats.  

Science.gov (United States)

Water-free Na+ storage may buffer extracellular volume and mean arterial pressure (MAP) in spite of Na+ retention. We studied the relationship among internal Na+, K+, water balance, and MAP in Sprague-Dawley rats, with or without deoxycorticosterone-acetate (DOCA) salt, with or without ovariectomy (OVX). The rats were fed a low-salt (0.1% NaCl) or high-salt (8% NaCl) diet for 5 weeks. DOCA salt increased MAP (161+/-14 versus 123+/-4 mm Hg; P<0.05), and DOCA-OVX salt increased MAP further (181+/-22 mm Hg; P<0.05). DOCA salt increased the total body Na+ by &40% to 45%; however, water-free Na+ retention by osmotically inactive Na+ storage and by osmotically neutral Na+/K+ exchange allowed the rats to maintain the extracellular volume close to normal. DOCA-OVX salt rats showed similar Na+ retention. However, their osmotically inactive Na+ storage capacity was greatly reduced and only partially compensated by neutral Na+/K+ exchange, resulting in greater volume retention despite similar Na+ retention. For every 1% wet weight total body water gain, MAP increased by 2.3+/-0.2 mm Hg in DOCA salt rats and 2.5+/-0.3 mm Hg in DOCA-OVX salt rats. Because water-free Na+ retention buffered total body water content by 8% to 11% wet weight, we conclude that this internal Na+ escape buffered MAP. Extrarenal Na+ and volume balance seem to play an important role in long-term volume and MAP control. PMID:16636196

Titze, Jens; Luft, Friedrich C; Bauer, Katharina; Dietsch, Peter; Lang, Rainer; Veelken, Roland; Wagner, Hubertus; Eckardt, Kai-Uwe; Hilgers, Karl F

2006-06-01

128

Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration  

CERN Document Server

The inner structure of the earth is still a topic of discussion. Seismic measurements showed a structure of solid, liquid, solid which describes the mantle, outer core and inner core with the inner core in the center. The analysis of waveform doublets suggests now that the inner core is out of center and even of faster rotation than the mantel and crust. From the sum of Buoyancy and Gravity on the earth inner core, the position energy is plotted and together with the tangential tidal acceleration, it is derived that Earth Inner Core cannot be in a center position without additional force. The Earth Core System is explained as Hydrodynamic Bearing. The Eccentricities out of nutation due to the effects from the sun and moon are calculated as an approximation.

Wolf, M

2013-01-01

129

Jump conditions for pressure anisotropy and comparison with the Earth's bow shock  

Directory of Open Access Journals (Sweden)

Full Text Available Taking into account the pressure anisotropy in the solar wind, we study the magnetic field and plasma parameters downstream of a fast shock, as functions of upstream parameters and downstream pressure anisotropy. In our theoretical approach, we model two cases: a the perpendicular shock and b the oblique shock. We use two threshold conditions of plasma instabilities as additional equations to bound the range of pressure anisotropy. The criterion of the mirror instability is used for pressure anisotropy p perp /pparrallel > 1. Analogously, the criterion of the fire-hose instability is taken into account for pressure anisotropy p perp /pparrallel < 1. We found that the variations of the parallel pressure, the parallel temperature, and the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock. Finally, we compare our theory with plasma and magnetic field parameters measured by the WIND spacecraft.

D. F. Vogl

2001-01-01

130

SMALL-SCALE PRESSURE-BALANCED STRUCTURES DRIVEN BY MIRROR-MODE WAVES IN THE SOLAR WIND  

Energy Technology Data Exchange (ETDEWEB)

Recently, small-scale pressure-balanced structures (PBSs) have been studied with regard to their dependence on the direction of the local mean magnetic field B{sub 0} . The present work continues these studies by investigating the compressive wave mode forming small PBSs, here for B{sub 0} quasi-perpendicular to the x-axis of Geocentric Solar Ecliptic coordinates (GSE-x). All the data used were measured by WIND in the quiet solar wind. From the distribution of PBSs on the plane determined by the temporal scale and angle ?{sub xB} between the GSE-x and B{sub 0} , we notice that at ?{sub xB} = 115° the PBSs appear at temporal scales ranging from 700 s to 60 s. In the corresponding temporal segment, the correlations between the plasma thermal pressure P{sub th} and the magnetic pressure P{sub B}, as well as that between the proton density N{sub p} and the magnetic field strength B, are investigated. In addition, we use the proton velocity distribution functions to calculate the proton temperatures T and T{sub ?}. Minimum Variance Analysis is applied to find the magnetic field minimum variance vector B{sub N} . We also study the time variation of the cross-helicity ?{sub c} and the compressibility C{sub p} and compare these with values from numerical predictions for the mirror mode. In this way, we finally identify a short segment that has T > T{sub ?}, proton ? ? 1, both pairs of P{sub th}-P{sub B} and N{sub p}-B showing anti-correlation, and ?{sub c} ? 0 with C{sub p} > 0. Although the examination of ?{sub c} and C{sub p} is not conclusive, it provides helpful additional information for the wave mode identification. Additionally, B{sub N} is found to be highly oblique to B{sub 0} . Thus, this work suggests that a candidate mechanism for forming small-scale PBSs in the quiet solar wind is due to mirror-mode waves.

Yao, Shuo [School of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing 100083 (China); He, J.-S.; Tu, C.-Y.; Wang, L.-H. [Department of Geophysics, Peking University, Beijing (China); Marsch, E., E-mail: yaoshuo@cugb.edu.cn [Christian Albrechts University at Kiel, Kiel D-24118 (Germany)

2013-10-20

131

Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System. Experimental Design and Analysis Approach to Model Pressure and Temperature Effects in Hypersonic Wind Tunnel Research  

Science.gov (United States)

Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

Lynn, Keith C.; Commo, Sean A.; Johnson, Thomas H.; Parker, Peter A,

2011-01-01

132

Structural and electronic transitions in rare-earth metal hydrides at high pressures  

International Nuclear Information System (INIS)

Compression of rare-earth metal, Y, with hydrogen fluid produced insulating trihysdide YH3, which showed a structural transition from hexagonal to fcc metal lattice at about 10 GPa and successively an electronic transition with band gap closure at 23 GPa on further compression. (author)

133

The pressure dilation of a deep, jointed region of the earth  

Energy Technology Data Exchange (ETDEWEB)

A series of pressurization tests of a 3.5-km deep body of jointed crystalline rock has shown that both the pressure deformation (i.e., dilation) of the region and the boundary permeation are nonlinear functions of the effective stress. This is because the apertures for both the joints and microcracks are strong functions of the effective normal stress acting to close them. For a surface pressure increase from zero to 7.5 MPa, the fluid storage in the natural joints and microcracks in this 0.3 km{sup 3} volume of rock increased by 1470 m{sup 3}. The corresponding increase in fluid storage between 7.5 and 15 MPa was 1090 m{sup 3}. However, even at a surface pressure level of 15 MPa, the permeation loss rate from this large volume of rock is only 0.3 l/s after six months of pressure maintenance. Using transient nonlinear numerical modeling, it is shown that the pressure-dependent fracture permeability model of Gangi, and the fracture porosity equivalent, adequately represent the measured permeability and porosity data obtained to date from this continuing series of pressurization experiments.

Brown, D.W.; Robinson, B.A.

1990-03-05

134

Ternary systems M-Ni-C (M - ''light'' rare earth metal) at various pressures and temperatures  

International Nuclear Information System (INIS)

The phase cohmposition of alloys in M-Ni-C ternary systems (M=La, Ce, Pr, Nd, Sm) at pressures of 1.0, 5.0, 7.7 GPa and temperatures of 600, 800, 1100 K as well as atmospheric pressure and temperatures of 600, 850 and 1000 K is studied. The interrelation of volumetric effects of chemical reactions with variations in phase diagrams of binary M-N ernary M-N systems at the transition from loW to high pressures is determined

135

Remarks on earth pressure testing in accordance with prEN 489; Anmerkungen zur Erddruckpruefung gemaess prEN 489  

Energy Technology Data Exchange (ETDEWEB)

Earth pressure testing in the draft prEN 489 pre-insulated bonded pipe systems for underground district heating networks dated 3 October 2000 has been almost exactly adopted form the initial 1994 version. On the basis of their experience, the Fernwaerme-Forschungsinstitut in Hannover e.V. (Hanover District Heating Research Institute - FFI) and the Institut fuer Grundbau, Bodenmechanik und Energiewasserbau (Institute for Foundation Engineering, Soil Mechanics and Hydraulic Engineering) have serious doubts whether the load on the pipe joint in Earth pressure testing represents the actual load in practice. (orig.) [German] In den Entwurf prEN 489 'Werkmaessig gedaemmte Verbundmantelrohrsysteme fuer erdverlegte Fernwaermenetze' vom Oktober 2000 ist die 'Erddruckpruefung' gegenueber der Erstfassung von 1994 nahezu ungeaendert uebernommen worden. Das Fernwaerme-Forschungsinstitut in Hannover e.V. hegt aufgrund seiner seit mehr als 20 Jahren andauernden eigenen Entwicklung der Erddruckpruefung und der dabei gewonnenen Erfahrungen ernsthafte Zweifel, ob die Belastung der Muffenverbindung in der Erddruckpruefung die tatsaechliche Belastung in der Praxis repraesentiert. Das Institut fuer Grundbau, Bodenmechanik und Energiewasserbau der Universitaet Hannover hat aus bodenmechanischer Sicht seinerseits Vorstellungen dargelegt, die gerechtfertigte Bedenken gegenueber der Erddruckpruefung nach prEN 489 beinhalten. (orig.)

Achmus, M. [Hannover Univ. (DE). Inst. fuer Grundbau, Bodenmechanik und Energiewasserbau (IGBE); Brachetti, H.E. [Hannover Univ. (Germany); Grage, T.; Lin, P.T. [Fernwaerme-Forschungsinstitut in Hannover e.V., Hemmingen (Germany)

2001-09-01

136

Pressure-induced novel superconductivity and heavy fermion state in rare earth compounds  

International Nuclear Information System (INIS)

We have carried out the electrical resistivity measurements under high pressures up to 24 GPa for CeTX3 (T: Co and Ir, X: Si and Ge), CePd5Al2 and YbIr2Zn20 in order to investigate quantum criticality and superconductivity. Antiferromagnets CeTX3 with the non-centrosymmetric tetragonal structure show superconductivity under high pressures and reveal a huge upper critical field for H? [001]. An antiferromagnet CePd5Al2, which is an isostructural family of a heavy fermion superconductor NpPd5Al2, also shows superconductivity under high pressures. In these compounds, superconductivity appears in the vicinity of quantum critical point. On the other hand, YbIr2Zn20 without magnetic ordering approaches to the quantum critical point with increasing pressure and exhibits a super-heavy fermion state exceeding 10 J/(K2· mol).

137

Origin of "memory glass" effect in pressure-amorphized rare-earth molybdate single crystals  

Science.gov (United States)

The memory glass effect (MGE) describes the ability of some materials to recover the initial structure and crystallographic orientation after pressure-induced amorphization (PIA). In spite of numerous studies the nature and underlying mechanisms of this phenomenon are still not clear. Here we report investigations of MGE in ??-Eu2(MoO4)3 single crystal samples subjected to high pressure amorphization. Using the XRD and TEM techniques we carried out detailed analysis of the structural state of high pressure treated single crystal samples as well as structural transformations due to subsequent annealing at atmospheric pressure. The structure of the sample has been found to be complex, mainly amorphous, however, the amorphous medium contains evenly distributed nanosize inclusions of a paracrystalline phase. The inclusions are highly correlated in orientation and act as "memory units" in the MGE.

Willinger, Elena; Sinitsyn, Vitaly; Khasanov, Salavat; Redkin, Boris; Shmurak, Semeon; Ponyatovsky, Eugeny

2015-02-01

138

Hydrogen and deuterium sorption by selected rare earth intermetallic compounds at pressures up to 1500 atm  

International Nuclear Information System (INIS)

A limited survey was conducted of hydrogen and deuterium sorption by 13 selected ABsub(x) alloys (A equivalent to La, Ce, Pr, Er; B equivalent to Co, Ni). A structural analysis showed that AB5 hydrides share essentially the same structure, with a maximum of nine sites per AB5 unit available for hydrogen storage. To determine whether all nine sites could be filled at pressures higher than those previously studied, pressure-composition isotherms were obtained at 21 0C and up to 1500 atm for each of the alloys under study. The effect on the pressure-composition isotherm of substituting one A or B element for another (neodymium or manganese) was also explored. The pressure plateaus were usually shifted by these substitutions. (Auth.)

139

Direct qualitative and quantitative determination of rare earths after separation by high pressure liquid chromatography (HPLC)  

International Nuclear Information System (INIS)

The rare earths from lanthanum to erbium can be separated by means of HPLC in an eluent system containing di-isopropylether/tetrahydrofuran/nitric acid (100:30:3), and they are determined qualitatively and quantitatively after calibration. Fluorescence quenching of THF at break-through of the single elements serves as indication method. This quenching is proportional to the concentration. The calibration curve is linear within 0.2 to 0.02 moles input. Standards, ores (monazites, cerite earths, yttriae) and technical products were analysed qualitatively and quantitatively. The results obtained are in good agreement with analytical values from different methods. The relative standard deviation is 1.8-3% (N = 10). The procedure takes 50 min from dissolution of the analytical sample. (orig.)

140

High-pressure elastic properties of major materials of Earth's mantle from first principles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The elasticity of materials is important for our understanding of processes ranging from brittle failure, to flexure, to the propagation of elastic waves. Seismologically revealed structure of the Earth's mantle, including the radial (one-dimensional) profile, lateral heterogeneity, and anisotropy are determined largely by the elasticity of the materials that make up this region. Despite its importance to geophysics, our knowledge of the elasticity of potentially relevant mineral phases at co...

Karki, B. B.; Stixrude, L.; Wentzcovitch, R. M.

2001-01-01

 
 
 
 
141

Unified understanding of the valence transition in the rare-earth monochalcogenides under pressure  

Science.gov (United States)

Valence instability is a key ingredient of the unusual properties of f electron materials, yet a clear understanding is lacking as it involves a complex interplay between f electrons and conduction states. Here we propose a unified picture of pressure-induced valence transition in Sm and Yb monochalcogenides, considered as a model system for mixed valent 4f-electron materials. Using high-resolution x-ray-absorption spectroscopy, we show that the valence transition is driven by the promotion of a 4f electron specifically into the lowest unoccupied (LU) 5d t2g band. We demonstrate with a promotional model that the nature of the transition at low pressures is intimately related to the density of states of the LU band, while at high pressures it is governed by the hybridization strength.

Jarrige, I.; Yamaoka, H.; Rueff, J.-P.; Lin, J.-F.; Taguchi, M.; Hiraoka, N.; Ishii, H.; Tsuei, K. D.; Imura, K.; Matsumura, T.; Ochiai, A.; Suzuki, H. S.; Kotani, A.

2013-03-01

142

Phase transformations in americium at high pressure: Relation to rare earth elements  

International Nuclear Information System (INIS)

The crystal structure of 241Am has been investigated up to 18.0 GPa, using a diamond anvil high-pressure apparatus. The normal dhep form of Am, stable at 1 atm and room temperature, undergoes three-phase transformations below 18.0 GPa. The first transformation occurs at about 5.0 +- 1.0 GPa, the second occurs at about 10.0 +- 1.0 GPa, and the third occurs at about 15.0 +- 1.0 GPa. The structure of the Am phase at 5-GPa pressure is fcc. However, we are unable to determine the structure of the new phases at about 10.0- and 15.0-GPa pressure from our present data. The structural behavior of Am showing that Am undergoes a sequence of structural transformations somewhat similar to the lanthanide metals is discussed

143

3-D Force-balanced Magnetospheric Configurations  

International Nuclear Information System (INIS)

The knowledge of plasma pressure is essential for many physics applications in the magnetosphere, such as computing magnetospheric currents and deriving magnetosphere-ionosphere coupling. A thorough knowledge of the 3-D pressure distribution has however eluded the community, as most in-situ pressure observations are either in the ionosphere or the equatorial region of the magnetosphere. With the assumption of pressure isotropy there have been attempts to obtain the pressure at different locations by either (a) mapping observed data (e.g., in the ionosphere) along the field lines of an empirical magnetospheric field model or (b) computing a pressure profile in the equatorial plane (in 2-D) or along the Sun-Earth axis (in 1-D) that is in force balance with the magnetic stresses of an empirical model. However, the pressure distributions obtained through these methods are not in force balance with the empirical magnetic field at all locations. In order to find a global 3-D plasma pressure distribution in force balance with the magnetospheric magnetic field, we have developed the MAG-3D code, that solves the 3-D force balance equation J x B = (upside-down delta) P computationally. Our calculation is performed in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials as B = (upside-down delta) psi x (upside-down delta) alpha. The pressure distribution, P = P(psi,alpha), is prescribed in the equatorial plane and is based on satellite measurements. In addition, computational boundary conditions for y surfaces are imposed using empirical field models. Our results provide 3-D distributions of magnetic field and plasma pressure as well as parallel and transverse currents for both quiet-time and disturbed magnetospheric conditions

144

Effect of pressure on the crystal field splitting in rare earth pnictides and chalcogenides  

Energy Technology Data Exchange (ETDEWEB)

The experimental situation for the pressure dependence of the crystal field of praseodymium pnictides and chalcogenides is reviewed and compared with the predictions of the point charge model. The problem of separating exchange and crystal field contributions from the measured NMR frequency shift or susceptibility measurements is discussed as well as problems explaining these effects with conduction electron related models.

Schirber, J.E.; Weaver, H.T.

1978-01-01

145

Elemental and isotope behaviour at ultra-high pressure (UHP) conditions: Earth and Environment  

... Therse rocks contain extremely light Li isotope ratios (bulk rocks, garnets and omphacite) and are with very radiogenic Os and Sr isotope signatures. We now investigate the elemental and isotopic influence that the host gneiss may play in shaping the geochemistry of the high pressure eclogite lenses and layers. Collaborators: & nbsp ...

146

Towards a unified understanding of the valence transition in rare-earth systems under pressure  

Science.gov (United States)

Valence instability is a key ingredient of the unusual properties of f electron materials, yet a clear understanding is lacking as it involves a complex interplay between f electrons and conduction states. I will present a unified picture of pressure-induced valence transition using lanthanum monochalcogenides as model system for 4f-electron materials. Using high-resolution x-ray absorption spectroscopy, I will show that the pressure-induced valence transition in Sm and Yb monochalcogenides is driven by the promotion of a 4f electron into the lowest unoccupied (LU) 5dt2g band. This band holds the key to explaining the diverse transitions of the monochalcogenides, offering a complete picture of the f electron delocalization mechanism. I demonstrate with a promotional model that the nature of the transition at low pressures is intimately related to the density of states of the LU band, while at high pressures it is governed by the hybridization strength. These results set a new standard for the generic understanding of valence fluctuations in f-electron materials.

Jarrige, Ignace; Yamaoka, Hitoshi; Rueff, Jean-Pascal; Lin, Jung-Fu; Taguchi, Munetaka; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding; Imura, Keiichiro; Matsumura, Takeshi; Ochiai, Akira; Suzuki, Hiroyuki; Kotani, Akio

2013-03-01

147

Mecanismos fisiopatológicos del desbalance glomérulo-tubular en la hipertensión arterial / Pathophysiological mechanisms of the lack of glomerulus-tubule balance in arterial high blood pressure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Cuba | Language: Spanish Abstract in spanish Las actuales tendencias e hipótesis para interpretar los mecanismos etiopatogénicos de la hipertensión arterial esencial, involucran al sistema renal como mecanismo preponderante en la regulación a largo plazo de la presión arterial y la existencia en él de algún fenómeno que puede conllevar a desba [...] lance glomérulo-tubular, con preponderancia tubular Aunque el análisis de este último hecho no ha sido como tal abordado en la patogénesis del síndrome hipertensivo. Con el objetivo de interpretar el papel del desbalance glomérulo-tubular, con preponderancia tubular en la fisiopatología de la hipertensión arterial como fenómeno en el que confluyen múltiples mecanismos fisiopatológicos renales ya descritos, se revisaron estos últimos, de forma integrada y su relación causal con el desbalance glomérulo-tubular, con preponderancia tubular. La preponderancia tubular, punto común de los mecanismos que se discuten, favorece la disminución de la excreción fraccional de Na+, la retención hidrosalina y la elevación de la presión arterial. Abstract in english The current trends and hypotheses to know the etiopathogenesis mechanisms of the essential arterial high blood pressure involved the renal system as a prevailing mechanism in the long-term regulation of arterial pressure and the existence in it of some phenomenon that could lead to a glomerulus-tubu [...] le lack of balance with tubular preponderance. Although the analysis of this latter fact, has not been approached as such in pathogenesis of hypertensive syndrome. With the aim of to interpret the role of glomerulus-tubule lack of balance with tubular preponderance in pathophysiology of arterial high blood pressure as a phenomenon in which converging multiple renal pathophysiological mechanisms already described, these latter were reviewed in a integrated way and its causal relation with the above mentioned lack of balance with tubular preponderance. This preponderance, a common point of discussed mechanisms, favors the decrease of a fractional releasing of Na+, the hydrosaline retention and the raise of arterial pressure.

María Ofelia, Barber Fox; Katiana, Galvizu Díaz; Aydelín, Pérez Ramos; María Ofelia, Fox Pascual.

2010-12-01

148

Effect of Chemical Pressure on the Charge Density Wave Transition in Rare-earth Tritellurides RTe_3  

CERN Document Server

The charge density wave transition is investigated in the bi-layer family of rare earth tritelluride RTe_3 compounds (R = Sm, Gd, Tb, Dy, Ho, Er, Tm) via high resolution x-ray diffraction and electrical resistivity. The transition temperature T_{CDW} increases monotonically with increasing lattice parameter by an extraordinarily large amount, from 244(3) K for TmTe_3 to 416(3) K for SmTe_3. It is suggested that this behavior, and the observation of a secondary transition for the heaviest members of the series, is intimately linked to the effect of chemical pressure on the degree of bilayer splitting of the Fermi surface.

Ru, N; Shin, K Y; Toney, M F; Fisher, I R

2006-01-01

149

General behavior of chalcogenides of rare-earth metals in transition to the intermediate valence state under high pressures  

Science.gov (United States)

High-precision measurements of the electric resistance, thermopower, and volume of TmS, TmSe, and TmTe under hydrostatic pressures up to 8.5 GPa were conducted. Comparison of the behavior of the electron-transport characteristics and volume of TmTe and SmTe in the electron transition region demonstrates a complete analogy up to the quantitative coincidence. We found that the thermopower of all samarium and thulium chalcogenides in the lattice-collapse region and during the subsequent reconstruction of the electronic spectrum obeys the universal dependence, which corresponds to the intersection of the Fermi level with the peak of the electron density of states. The results obtained testify in favor of the exciton nature of the intermediate valence state in chalcogenides of the rare-earth metals.

Tsiok, O. B.; Khvostantsev, L. G.; Golubkov, A. V.; Smirnov, I. A.; Brazhkin, V. V.

2014-10-01

150

Raman scattering of rare earth sesquioxide Ho2O3: A pressure and temperature dependent study  

International Nuclear Information System (INIS)

Pressure and temperature dependent Raman scattering studies on Ho2O3 have been carried out to investigate the structural transition and the anharmonic behavior of the phonons. Ho2O3 undergoes a transition from cubic to monoclinic phase above 15.5?GPa, which is partially reversible on decompression. The anharmonic behavior of the phonon modes of Ho2O3 from 80?K to 440?K has been investigated. We find an anomalous line-width change with temperature. The mode Grüneisen parameter of bulk Ho2O3 was estimated from high pressure Raman investigation up to 29?GPa. Furthermore, the anharmonic components were calculated from the temperature dependent Raman scattering.

151

High Pressure, Earth-Storable Rocket Technology. Volume 3; Appendices C and D  

Science.gov (United States)

The effect of elevated chamber pressure on combustion efficiency and heat transfer has been determined at the 100 lbf (445 N) thrust level for nitrogen tetroxide propellants. Measurements were made up to 500 psia (3.45 MPa) with testbed hardware; tests at 100 psia (0.690 MPa) and 250 psia (1.72 MPa) were made with radiation-cooled rhenium chambers. The first task of the program served to determine desirable thruster applications and operating conditions: high total impulse, i.e. communication satellite or spacecraft bus axial engines, at chamber pressures up to 250 psia (1.72 MPa) pressure-fed, or up to 500 psia (3.45 MPa) pump-fed. The hardware modifications and testing required to obtain the data were determined in Task 2, which included design-support hot fire tests; supplemental hardware, including a 250 psia (1.72 MPa) Pc rhenium chamber and a 20% fuel-film cooled platelet injector was fabricated in Task 3. Testing showed that satisfactory operation of Ir-Re radiation chambers is assured at pressures up to 250 psia and may be possible up to 500. The heat transfer data obtained show good correlation with throat Reynolds number and are generally under values given by the simplified Bartz equation; chambers equilibrium temperatures match predicted values. Preliminary optimization of trip configuration and mixture ratio were made; Isp performance from thrust measurements was within 1% of predicted values. Stability, compatibility, and front-end thermal management were determined to be satisfactory.

Jassowski, D. M.

1997-01-01

152

ON PHASE TRANSITIONS AND STRUCTURAL SYSTEMATICS I N ALKALINE EARTH METALS UNDER PRESSURE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The crystal structures of Mg, Ca, Sr and Ba were studied by energy dispersive X-ray diffraction at room temperature and pressures up to 50 GPa. Mg transforms around 50 GPa from hcp to bcc. Structura1 transitions to bcc and to a simple cubic structure are observed in Ca at 19.5 and 32 GPa respectively. Sr shows the well known transition from fcc to bcc at 3.5 GPa and additional phase transitions around 26, 35 and 46 GPa, which lead ultimately to the Ba-IV-structure. The experiments on Ba gave ...

Olijnyk, H.; Holzapfel, W.

1984-01-01

153

Local structure around rare-earth ions in B{sub 2}O{sub 3} glass at high pressure  

Energy Technology Data Exchange (ETDEWEB)

Melt quenching of B{sub 2}O{sub 3} with less than 25 mol. % rare-earth oxide (RE{sub 2}O{sub 3}) at ambient pressure results in a milky white glass because of liquid-liquid phase separation into B{sub 2}O{sub 3} and RE{sub 2}O{sub 3}{center_dot}3B{sub 2}O phases. In contrast, we have found that melt quenching under GPa-order pressure realizes a transparent RE-doped B{sub 2}O{sub 3} glass. This study investigates the local structure around the RE ions in the B{sub 2}O{sub 3} glass prepared at 3 GPa using optical measurements and electron-spin-echo envelope modulation spectroscopy. It is shown that the RE-rich microparticles disappear and the RE ions are isolated from each other in a highly symmetric crystal field formed by triangular and tetrahedral boron units. This result is consistent with that extrapolated from the data for RE-doped sodium borate glasses.

Funabiki, Fuji [Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503 (Japan); Matsuishi, Satoru [Research Center for Strategic Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503 (Japan); Hosono, Hideo [Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503 (Japan); Research Center for Strategic Materials, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8503 (Japan)

2013-06-14

154

Effect of chemical and hydrostatic pressures on structural and magnetic properties of rare-earth orthoferrites: a first-principles study  

Science.gov (United States)

The dependence of structural and magnetic properties of rare-earth orthoferrites (in their Pbnm ground state) on the rare-earth ionic radius is systematically investigated from first principles. The effects of this ‘chemical pressure’ on lattice constants, Fe-O bond lengths, Fe-O-Fe bond angles and Fe-O bond length splittings are all well reproduced by these ab initio calculations. The simulations also offer novel predictions (on tiltings of FeO6 octahedra, cation antipolar displacements and weak magnetization) to be experimentally checked. In particular, the weak ferromagnetic moment of rare-earth orthoferrites is predicted to be a linear function of the rare-earth ionic radius. Finally, the effects of applying hydrostatic pressure on structural and magnetic behavior of SmFeO3 is also studied. It is found that, unlike previously assumed, hydrostatic pressure typically generates changes in physical properties that are quantitatively and even qualitatively different from those associated with the chemical pressure.

Zhao, Hong Jian; Ren, Wei; Yang, Yurong; Chen, Xiang Ming; Bellaiche, L.

2013-11-01

155

Effect of chemical and hydrostatic pressures on structural and magnetic properties of rare-earth orthoferrites: a first-principles study.  

Science.gov (United States)

The dependence of structural and magnetic properties of rare-earth orthoferrites (in their Pbnm ground state) on the rare-earth ionic radius is systematically investigated from first principles. The effects of this 'chemical pressure' on lattice constants, Fe-O bond lengths, Fe-O-Fe bond angles and Fe-O bond length splittings are all well reproduced by these ab initio calculations. The simulations also offer novel predictions (on tiltings of FeO6 octahedra, cation antipolar displacements and weak magnetization) to be experimentally checked. In particular, the weak ferromagnetic moment of rare-earth orthoferrites is predicted to be a linear function of the rare-earth ionic radius. Finally, the effects of applying hydrostatic pressure on structural and magnetic behavior of SmFeO3 is also studied. It is found that, unlike previously assumed, hydrostatic pressure typically generates changes in physical properties that are quantitatively and even qualitatively different from those associated with the chemical pressure. PMID:24135000

Zhao, Hong Jian; Ren, Wei; Yang, Yurong; Chen, Xiang Ming; Bellaiche, L

2013-11-20

156

Effects of chemical and hydrostatic pressures on structural, magnetic, and electronic properties of R2NiMn O6 (R =rare -earth ion ) double perovskites  

Science.gov (United States)

The effects of chemical and hydrostatic pressures on structural, magnetic, and electronic properties of R2NiMn O6 double perovskites, with R being a rare-earth ion, have been systematically studied by using specific first-principles calculations. These latter reproduce well the correlation between several properties (e.g., lattice parameters, Ni-O-Mn bond angles, magnetic Curie temperature, and electronic band gap) and the rare-earth ionic radius (i.e., the chemical pressure). They also provide novel predictions awaiting experimental confirmation, such as (i) that many physical quantities respond in dramatically different manners to chemical versus hydrostatic pressure, unlike as commonly thought for perovskites containing rare-earth ions, and (ii) a dependence of antipolar displacements on chemical and hydrostatic pressures, which would further explain why the recently predicted electrical polarization of L a2NiMn O6/R2NiMn O6 superlattices [H. J. Zhao, W. Ren, Y. Yang, J. Íñiguez, X. M. Chen, and L. Bellaiche, Nat. Commun. 5, 4021 (2014), 10.1038/ncomms5021] can be created and controlled by playing with the rare-earth element.

Zhao, Hong Jian; Liu, Xiao Qiang; Chen, Xiang Ming; Bellaiche, L.

2014-11-01

157

Effect of chemical and hydrostatic pressures on structural and magnetic properties of rare-earth orthoferrites: a first-principles study  

International Nuclear Information System (INIS)

The dependence of structural and magnetic properties of rare-earth orthoferrites (in their Pbnm ground state) on the rare-earth ionic radius is systematically investigated from first principles. The effects of this ‘chemical pressure’ on lattice constants, Fe–O bond lengths, Fe–O–Fe bond angles and Fe–O bond length splittings are all well reproduced by these ab initio calculations. The simulations also offer novel predictions (on tiltings of FeO6 octahedra, cation antipolar displacements and weak magnetization) to be experimentally checked. In particular, the weak ferromagnetic moment of rare-earth orthoferrites is predicted to be a linear function of the rare-earth ionic radius. Finally, the effects of applying hydrostatic pressure on structural and magnetic behavior of SmFeO3 is also studied. It is found that, unlike previously assumed, hydrostatic pressure typically generates changes in physical properties that are quantitatively and even qualitatively different from those associated with the chemical pressure. (paper)

158

Analytical Third Order Solution for Coupling Effects of Earth Oblateness and Direct Solar Radiation Pressure on the Motion of Artificial Satellites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Coupling effects of Earth oblateness and direct solar radiation pressure on the motion of an artificial satellite are evaluated. Secular and periodic terms are retained up to order three and two respectively, where the coefficient of the second zonal harmonic of the geopotential is considered of first order. The solution revealed the existenc...

Hadia Hassan Selim

2014-01-01

159

Postural balance in low back pain patients: Intra-session reliability of center of pressure on a portable force platform and of the one leg stand test  

DEFF Research Database (Denmark)

Low back pain (LBP) patients have poorer postural control compared to healthy controls, and the importance of assessing and addressing balance is a matter of debate. In the clinic, balance is often tested by means of the one leg stand test (OLST) while research often employs center of pressure (CoP) on a force platform. Portable force platforms might be of clinical relevance, but their reliability for LBP patients in a clinical setting has not been demonstrated. As LBP patients are more dependent on vision compared to healthy controls, the ratio of tests performed with eyes open and eyes closed (Romberg Ratio) might be of clinical interest. This study aimed to assess postural balance in LBP patients by analyzing intra-session reliability of CoP parameters on a portable force platform, the Romberg Ratio, and the OLST. Furthermore, we aimed to determine whether CoP parameters and OLST measure identical aspects of postural stability. We examined 49 LBP patients and found acceptable reliability of the CoP parameters' trace length and velocity, whereas reliability regarding C90 area, the Romberg Ratio, and the OLST was poor. Correlations between the CoP parameters and OLST were insignificant. Reliability of trace length and velocity is acceptable and can be used as parameters when assessing CoP in LBP patients.

Maribo, Thomas; Stengaard-Pedersen, Kristian

2011-01-01

160

Postural balance in low back pain patients : Intra-session reliability of center of pressure on a portable force platform and of the one leg stand test  

DEFF Research Database (Denmark)

Low back pain (LBP) patients have poorer postural control compared to healthy controls, and the importance of assessing and addressing balance is a matter of debate. In the clinic, balance is often tested by means of the one leg stand test (OLST) while research often employs center of pressure (CoP) on a force platform. Portable force platforms might be of clinical relevance, but their reliability for LBP patients in a clinical setting has not been demonstrated. As LBP patients are more dependent on vision compared to healthy controls, the ratio of tests performed with eyes open and eyes closed (Romberg Ratio) might be of clinical interest. This study aimed to assess postural balance in LBP patients by analyzing intra-session reliability of CoP parameters on a portable force platform, the Romberg Ratio, and the OLST. Furthermore, we aimed to determine whether CoP parameters and OLST measure identical aspects of postural stability. We examined 49 LBP patients and found acceptable reliability of the CoP parameters' trace length and velocity, whereas reliability regarding C90 area, the Romberg Ratio, and the OLST was poor. Correlations between the CoP parameters and OLST were insignificant. Reliability of trace length and velocity is acceptable and can be used as parameters when assessing CoP in LBP patients.

Maribo, Thomas; Stengaard-Pedersen, Kristian

2011-01-01

 
 
 
 
161

Pressurizer  

International Nuclear Information System (INIS)

A thin walled tube is welded on to the coupling of the overpressure protection in the lid of the pressurizer. The tube opening is located above the highest possible water level in the pressurizer occurring at different regimes of the nuclear power plant. The advantage of the configuration is that an elastic steam cushion is always preserved in the pressurizer during an accident. (Ha)

162

Pressure sensor-based tongue-placed electrotactile biofeedback for balance improvement - Biomedical application to prevent pressure sores formation and falls.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We introduce the innovative technologies, based on the concept of "sensory substitution", we are developing in the fields of biomedical engineering and human disability. Precisely, our goal is to design, develop and validate practical assistive biomedical and/or technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in c...

Vuillerme, Nicolas; Chenu, Olivier; Pinsault, Nicolas; Moreau-gaudry, Alexandre; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

2007-01-01

163

Chaotic behavior in a system simulating the pressure balanced injection system. Analysis of passive safety reactor behavior. JAERI's nuclear research promotion program, H12-012 (Contract research)  

International Nuclear Information System (INIS)

The pressure Balanced Injection System (PBIS) was proposed in a passive safety reactor. Pressurizing Line (PL) connects the Reactor Vessel (RV) and the gas area in the Contain Vessel (CV), and Injected Line (IL) connects two vessels at relatively lower position. In an accident, the two lines are passively opened. The vapor generated by the residual heat pressed downward the water level in the RV. When the level is lower than the inlet of the PL, vapor is ejected into the CV through the PL attaining the pressure balance between the vessels. Then boron water in the CV is injected into the RV through the IL by the static head. This process is repeated by the succeeding vapor generation. In an experiment, the oscillating system was replaced by water column in a U-shaped duct. The vapor generation was simulated by cover gas supply to one end of the duct, while the other end was open to the atmosphere. When the water level reached a certain level, electromagnetic valves opened and the cover gas was ejected. The gas pressure decreased rapidly, resulting in a surface rise. When the water level reached another level, the valves closed. The cover gas pressure increased again, thus, gas ejection occurred intermittently. The interval of the gas ejection was not constant but fluctuated widely. Mere stochastic noise could hardly explain the large amplitude. Then was expressed the system using a set of linear equations. Various types of piecewise linear model were developed to examine the cause of the fluctuation. There appeared tangential bifurcation, period-doubling bifurcation, period-adding bifurcation and so on. The calculated interval exhibited chaotic features. Thus the cause of the fluctuation can be attributed to chaotic features of the system having switching. Since the piecewise linear model was highly simplified the behavior, a quantitative comparison between the calculation and the experiment was difficult. Therefore, numerical simulation code considering nonlinear effect was developed to describe the system behavior in the case there was no stochastic noise. The comparison between the simulation and the experiment revealed that there are some bifurcation-like phenomena being not real bifurcations. Real bifurcations are discovered in the simulation as well as in the experiment. Confirmation of chaotic behavior of the system in the experiment is a subject for a future study. (author)

164

High-pressure syntheses and characterization of the rare-earth fluoride borates RE2(BO3)F3 (RE = Tb, Dy, Ho)  

International Nuclear Information System (INIS)

The new rare-earth fluoride borates RE2(BO3)F3 (RE = Tb, Dy, Ho) were synthesized under high-pressure/high-temperature conditions of 1.5 GPa/1200 C for Tb2(BO3)F3 and 3.0 GPa/900 C for Dy2(BO3)F3 and Ho2(BO3)F3 in a Walker-type multianvil apparatus from the corresponding rare-earth sesquioxides, rare-earth fluorides, and boron oxide. The single-crystal structure determinations revealed that the new compounds are isotypic to the known rare-earth fluoride borate Gd2(BO3)F3. The new rare-earth fluoride borates crystallize in the monoclinic space group P21/c (Z = 8) with the lattice parameters a = 16.296(3), b = 6.197(2), c = 8.338(2) A, ? = 93.58(3) for Tb2(BO3)F3, a = 16.225(3), b = 6.160(2), c = 8.307(2) A, ? = 93.64(3) for Dy2(BO3)F3, and a = 16.189(3), b = 6.124(2), c = 8.282(2) A, ? = 93.69(3) for Ho2(BO3)F3. The four crystallographically different rare-earth cations (CN = 9) are surrounded by oxygen and fluoride anions. All boron atoms form isolated trigonal-planar [BO3]3- groups. The six crystallographically different fluoride anions are in a nearly planar coordination by three rare-earth cations. (orig.)

165

Shp2 signaling in POMC neurons is important for leptin's actions on blood pressure, energy balance, and glucose regulation.  

Science.gov (United States)

Previous studies showed that Src homology-2 tyrosine phosphatase (Shp2) is an important regulator of body weight. In this study, we examined the impact of Shp2 deficiency specifically in proopiomelanocortin (POMC) neurons on metabolic and cardiovascular function and on chronic blood pressure (BP) and metabolic responses to leptin. Mice with Shp2 deleted in POMC neurons (Shp2/Pomc-cre) and control mice (Shp2(flox/flox)) were implanted with telemetry probes and venous catheters for measurement of mean arterial pressure (MAP) and leptin infusion. After at least 5 days of stable control measurements, mice received leptin infusion (2 ?g·kg(-1)·day(-1) iv) for 7 days. Compared with Shp2(flox/flox) controls, Shp2/Pomc-cre mice at 22 wk of age were slightly heavier (34 ± 1 vs. 31 ± 1 g) but consumed a similar amount of food (3.9 ± 0.3 vs. 3.8 ± 0.2 g/day). Leptin infusion reduced food intake in Shp2(flox/flox) mice (2.6 ± 0.5 g) and Shp2/Pomc-cre mice (3.2 ± 0.3 g). Despite decreasing food intake, leptin infusion increased MAP in control mice, whereas no significant change in MAP was observed in Shp2/Pomc-cre mice. Leptin infusion also decreased plasma glucose and insulin levels in controls (12 ± 1 to 6 ± 1 ?U/ml and 142 ± 12 to 81 ± 8 mg/100 ml) but not in Shp2/Pomc-cre mice. Leptin increased V?o2 by 16 ± 2% in controls and 7 ± 1% in Shp2/Pomc-cre mice. These results indicate that Shp2 signaling in POMC neurons contributes to the long-term BP and antidiabetic actions of leptin and may play a modest role in normal regulation of body weight. PMID:25339680

do Carmo, Jussara M; da Silva, Alexandre A; Ebaady, Sabira E; Sessums, Price O; Abraham, Ralph S; Elmquist, Joel K; Lowell, Bradford B; Hall, John E

2014-12-15

166

Achieving high-pressure and high-temperature within a TEM: Crystallographic defects as hosts for concentrating and storing carbon deep within Earth  

Science.gov (United States)

Transmission electron microscopy in combination with in-situ high-pressure and high-temperature measurements is uniquely able to provide high-resolution data about materials under conditions resembling those in Earth's interior. By using nanocontainers of graphitized carbon, it is possible to achieve pressures and temperatures up to 40 GPa and 1200 °C, respectively. A wide range of relatively simple minerals and mineral analogs have been examined using this approach. By studying alpha-PbO2-type titanium dioxide (TiO2) and perovskite-structured nickel-doped lanthanum chromate (LaCr0.5Ni0.5O3), we show the influence of crystallographic defects in concentrating and storing carbon within these analogs to minerals occurring deep inside Earth. Such in-situ observations are impossible by using existing conventional high-pressure techniques. Figure 1. Temporal compression sequence of an anatase nanocrystal with two visible fault planes inside a multi-walled graphitic cage. (a)-(g) The times indicated in each panel are from the start of irradiation. Pressure was generated by shrinkage of the cage resulting from displacement damage by electrons (30 A/cm2) at 770 C. The disappearance of anatase (101) planes and emergence of alpha-PbO2-type TiO2 (110) planes indicates a phase transition between (e) and (f) (see insets).

Wu, J.; Buseck, P. R.

2013-12-01

167

SPES-2, AP600 intergral system test S01007 2 inch CL to core make-up tank pressure balance line break  

International Nuclear Information System (INIS)

The SPES-2 is a full height, full pressure experimental test facility reproducing the Westinghouse AP600 reactor with a scaling factor of 1/395. The experimental plant, designed and operated by SIET in Piacenza, consists of a full simulation of the AP600 primary core cooling system including all the passive and active safety systems. In 1992, Westinghouse, in cooperation with ENEL (Ente Nazionale per l' Energia Elettrica), ENEA (Enter per le numove Technlogie, l' Energia e l' Ambient), Siet (Societa Informazioni Esperienze Termoidraulich) and ANSALDO developed an experimental program to test the integrated behaviour of the AP600 passive safety systems. The SPES-2 test matrix, concluded in November 1994, has examined the AP600 passive safety system response for a range of small break LOCAs at different locations on the primary system and on the passive system lines; single steam generator tube ruptures with passive and active safety systems and a main steam line break transient to demonstrate the boration capability of passive safety systems for rapid cooldown. Each of the tests has provided detailed experimental results for verification of the capability of the analysis methods to predict the integrated passive safety system behaviour. Cold and hot shakedown tests have been performed on the facility to check the characteristics of the plant before starting the experimental campaign. The paper first presents a description of the SPES-2 test facility then the main resule SPES-2 test facility then the main results of S01007 test open-quotes 2close quotes Cold Leg (CL) to Core Make-up Tank (CMT) pressure balance line breakclose quotes are reported and compared with predictions performed using RELAP5/mod3/80 obtained by ANSALDO through agreement with U.S.N.R.C. (U.S. Nuclear Regulatory Commission). The SPES-2 nodalization and all the calculations here presented were performed by ANSALDO and sponsored by ENEL as a part of pre-test predictions for SPES-2

168

Earth materials and earth dynamics  

Energy Technology Data Exchange (ETDEWEB)

In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

Bennett, K; Shankland, T. [and others

2000-11-01

169

Postural balance in low back pain patients : criterion-related validity of centre of pressure assessed on a portable force platform  

DEFF Research Database (Denmark)

INTRODUCTION: Altered postural control has been observed in low back pain (LBP) patients. They seem to be more dependent on vision when standing. The objective of the study was to determine concurrent and predictive validity of measures of postural stability in LBP patients. MATERIALS AND METHODS: Centre of Pressure (CoP) measurements were tested against pain, fear of pain, and physical function. Velocity, anterior-posterior displacement, and the Romberg Ratio obtained on a portable force platform were used as measures of postural stability. RESULTS: Baseline and 12-week follow-up results of 97 LBP patients were evaluated. The correlations between CoP measurements and pain, fear of pain, and physical function were poor. There were no significant differences in CoP measurements between patients with no change or deterioration and patients with improvement in pain and back-specific function. CONCLUSION: This first study of concurrent and predictive validity of postural balance in LBP patients revealed no association between CoP measures and pain, fear of pain, and physical function.

Maribo, Thomas; SchiØttz-Christensen, Berit

2012-01-01

170

Education and Outreach Programs Offered by the Center for High Pressure Research and the Consortium for Materials Properties Research in Earth Sciences  

Science.gov (United States)

Major research facilities and organizations provide an effective venue for developing partnerships with educational organizations in order to offer a wide variety of educational programs, because they constitute a base where the culture of scientific investigation can flourish. The Consortium for Materials Properties Research in Earth Sciences (COMPRES) conducts education and outreach programs through the Earth Science Educational Resource Center (ESERC), in partnership with other groups that offer research and education programs. ESERC initiated its development of education programs in 1994 under the administration of the Center for High Pressure Research (CHiPR), which was funded as a National Science Foundation Science and Technology Center from 1991 to 2002. Programs developed during ESERC's association with CHiPR and COMPRES have targeted a wide range of audiences, including pre-K, K-12 students and teachers, undergraduates, and graduate students. Since 1995, ESERC has offered inquiry-based programs to Project WISE (Women in Science and Engineering) students at a high school and undergraduate level. Activities have included projects that investigated earthquakes, high pressure mineral physics, and local geology. Through a practicum known as Project Java, undergraduate computer science students have developed interactive instructional tools for several of these activities. For K-12 teachers, a course on Long Island geology is offered each fall, which includes an examination of the role that processes in the Earth's interior have played in the geologic history of the region. ESERC has worked with Stony Brook's Department of Geosciences faculty to offer courses on natural hazards, computer modeling, and field geology to undergraduate students, and on computer programming for graduate students. Each summer, a four-week residential college-level environmental geology course is offered to rising tenth graders from the Brentwood, New York schools in partnership with Stony Brook's Department of Technology and Society. During the academic year, a college-level Earth science course is offered to tenth graders from Sayville, New York. In both programs, students conduct research projects as one of their primary responsibilities. In collaboration with the Museum of Long Island Natural Sciences on the Stony Brook campus, two programs have been developed that enable visiting K-12 school classes to investigate earthquakes and phenomena that operate in the Earth's deep interior. From 1997 to 1999, the weekly activity-based Science Enrichment for the Early Years (SEEY) program, focusing on common Earth materials and fundamental Earth processes, was conducted at a local pre-K school. Since 2002, ESERC has worked with the Digital Library for Earth System Education (DLESE) to organize the Skills Workshops for their Annual Meeting and with EarthScope for the development of their Education and Outreach Program Plan. Future education programs and tools developed through COMPRES partnerships will place an increased emphasis on deep Earth materials and phenomena.

Richard, G. A.

2003-12-01

171

Effect of Horizontal Drain Length and Cutoff Wall on Seepage and Uplift Pressure in Heterogeneous Earth Dam with Numerical Simulation  

Directory of Open Access Journals (Sweden)

Full Text Available Design of earth dams and their problems are important during construction and after it,because of their potential hazards and failure for downstream population. This study focus on theeffectiveness of using horizontal drain and cutoff wall in reducing seepage flow from an assumedheterogeneous earth dam. For this purpose various horizontal drain lengths and cutoff wall depth examineunder the earth dam in different location of foundation. Seepage analysis, hydraulic gradient and upliftpressure, are computing by numerical simulation, using Seep/w software. Results show that increasinghorizontal drain length, cause slightly in increasing seepage rate and increasing hydraulic gradient.Optimum location of cut off wall for reduction of seepage rate and piping is in the middle of damfoundation. By increasing in cut off wall depth, seepage from earth dam and its foundation is reducing.Different location of cut off wall in dam foundation has little effect on exit hydraulic gradient and always itis less than unity. Installation of cut off wall in middle of foundation, results 19.68 percent decreasing inhydraulic gradient respect to existent of cut off wall in upstream of dam.

Farzin Salmasi

2013-05-01

172

Análise da pressão plantar e do equilíbrio postural em diferentes fases da gestação / Analysis of plantar pressure and postural balance during different phases of pregnancy  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Analisar a pressão plantar e o equilíbrio postural nos três trimestres de gravidez, bem como a correlação com as características antropométricas. METODOLOGIA: 60 voluntárias com idade média de 23,3 ± 5,5 anos, sendo 15 mulheres em cada grupo: não-gestantes (C), primeiro (1T), segundo (2T) [...] e terceiro trimestre (3T). A avaliação foi efetuada por meio de plataforma de pressão na posição bipodal com os olhos abertos. As variáveis analisadas nos pés direito e esquerdo foram: pico de pressão em todo o pé (PT), no antepé (PA) e no retropé (PR); distância entre a borda medial dos pés (largura da base de suporte); distância do centro de força ao limite anterior (CFF) e posterior (CFC) dos pés; deslocamento ântero-posterior (AP) e médio--lateral (ML) do centro de força; e área de contato (AC). RESULTADOS: Não houve diferença no pico de pressão de contato e na distância CFF e CFC entre os grupos. O deslocamento AP foi maior (p 0,05) entre os grupos para o deslocamento ML. Houve correlação positiva entre peso ganho durante a gestação com AC para o grupo 2T e com PT no pé direito do grupo 1T. CONCLUSÃO: Os resultados demonstram a influência das mudanças anatômicas e fisiológicas inerentes à gestação na pressão plantar, além de sugerir uma redução do equilíbrio postural no 3T, relacionada ao maior deslocamento AP nessa fase. Abstract in english OBJECTIVE: To analyze plantar pressure and postural balance during the three trimesters of pregnancy, and also to correlate these with anthropometric characteristics. METHOD: Sixty volunteers participated in this study, with a mean age of 23.3 ± 5.5 years. There were 15 subjects in each group: non-p [...] regnant (C), first trimester (1T), second trimester (2T) and third trimester (3T). Evaluations were performed in bipedal stance with open eyes, using a pressure platform. The following variables were analyzed in the right and left feet: peak pressures in the whole foot (WFP), forefoot (FFP) and hindfoot (HFP); distance between the medial borders of the foot (width of support base); the distance from the center of force to the anterior (COF-A) and posterior (COF-P) limits of the foot; anteroposterior (AP) and mediolateral (ML) COF displacements; and the contact area (CA). RESULTS: There were no differences in peak contact pressures and COF-A and COF-P distances between the groups. The AP displacement was greater (p 0.05) between the groups regarding ML displacement. There was a positive correlation between weight gained during pregnancy and CA for the 2T group, and between weight gain and WFP in the right feet in the 1T group. CONCLUSION: The results demonstrate the influence of the anatomical and physiological changes inherent to pregnancy on plantar pressure. They also suggest that postural equilibrium decreases in the third trimester, associated with greater AP displacement during this phase.

SI, Ribas; ECO, Guirro.

2007-10-01

173

Análise da pressão plantar e do equilíbrio postural em diferentes fases da gestação Analysis of plantar pressure and postural balance during different phases of pregnancy  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Analisar a pressão plantar e o equilíbrio postural nos três trimestres de gravidez, bem como a correlação com as características antropométricas. METODOLOGIA: 60 voluntárias com idade média de 23,3 ± 5,5 anos, sendo 15 mulheres em cada grupo: não-gestantes (C, primeiro (1T, segundo (2T e terceiro trimestre (3T. A avaliação foi efetuada por meio de plataforma de pressão na posição bipodal com os olhos abertos. As variáveis analisadas nos pés direito e esquerdo foram: pico de pressão em todo o pé (PT, no antepé (PA e no retropé (PR; distância entre a borda medial dos pés (largura da base de suporte; distância do centro de força ao limite anterior (CFF e posterior (CFC dos pés; deslocamento ântero-posterior (AP e médio--lateral (ML do centro de força; e área de contato (AC. RESULTADOS: Não houve diferença no pico de pressão de contato e na distância CFF e CFC entre os grupos. O deslocamento AP foi maior (p 0,05 entre os grupos para o deslocamento ML. Houve correlação positiva entre peso ganho durante a gestação com AC para o grupo 2T e com PT no pé direito do grupo 1T. CONCLUSÃO: Os resultados demonstram a influência das mudanças anatômicas e fisiológicas inerentes à gestação na pressão plantar, além de sugerir uma redução do equilíbrio postural no 3T, relacionada ao maior deslocamento AP nessa fase.OBJECTIVE: To analyze plantar pressure and postural balance during the three trimesters of pregnancy, and also to correlate these with anthropometric characteristics. METHOD: Sixty volunteers participated in this study, with a mean age of 23.3 ± 5.5 years. There were 15 subjects in each group: non-pregnant (C, first trimester (1T, second trimester (2T and third trimester (3T. Evaluations were performed in bipedal stance with open eyes, using a pressure platform. The following variables were analyzed in the right and left feet: peak pressures in the whole foot (WFP, forefoot (FFP and hindfoot (HFP; distance between the medial borders of the foot (width of support base; the distance from the center of force to the anterior (COF-A and posterior (COF-P limits of the foot; anteroposterior (AP and mediolateral (ML COF displacements; and the contact area (CA. RESULTS: There were no differences in peak contact pressures and COF-A and COF-P distances between the groups. The AP displacement was greater (p 0.05 between the groups regarding ML displacement. There was a positive correlation between weight gained during pregnancy and CA for the 2T group, and between weight gain and WFP in the right feet in the 1T group. CONCLUSION: The results demonstrate the influence of the anatomical and physiological changes inherent to pregnancy on plantar pressure. They also suggest that postural equilibrium decreases in the third trimester, associated with greater AP displacement during this phase.

SI Ribas

2007-10-01

174

High Pressure Melting, Phase Diagrams, and Equations of State in the Fe-FeSi System with Application to Earth's Core  

Science.gov (United States)

The Earth's core is comprised mostly of iron, with some nickel and several weight percent of one or more light elements. The light element(s) dictate phase relations, structure, and dynamic behaviour, so it is crucial to evaluate various candidates at conditions of planetary interiors. We present results on high P-T phase diagrams and equations of state in the Fe-FeSi system with application to the structure and composition of Earth's core. X-ray diffraction measurements were performed on stoichiometric FeSi and on Fe-Si alloys containing 9 and 16 wt% silicon in a laser-heated diamond anvil cell at the APS, NSLS, and ALS. Pressures were determined from the lattice parameter of KBr. We have investigated the phase diagram of Fe-9Si to 100 GPa and over 3000 K. Our melting curve agrees with previous results on similar alloys [1,2], as demonstrated using multiple methods of detecting melting. Our subsolidus results are similar to those of Lin et al. [3], though we find the B2 structure instead of bcc, and a shallower slope for the hcp+B2 to fcc+B2 boundary. We studied phase relations of Fe-16Si to over 135 GPa, finding agreement with previous melting curves [2,4]. Below 45 GPa, this alloy has the D0_3 structure. At high pressures, Fe-16Si breaks down into a mixture of B2 and hcp phases, with this mixture stable to pressures of the Earth's outer core. This is the first study on the B2 phase of FeSi with in situ X-ray diffraction at high pressures and temperatures. We report a wide B2+B20 two-phase field in FeSi, with complete conversion to the B2 structure by ~42 GPa. A melting experiment on FeSi agrees with the results of Lord et al. [5]. We have synthesized our results with previous studies to construct T-X and P-X phase diagrams, and we have determined thermal equations of state of each alloy. Our measured densities can be used to constrain the maximum amount of silicon in the Earth's outer core by comparison to the equation of state of hcp-Fe [6] and the seismologically-determined density. Assuming a core-mantle boundary (CMB) temperature of 4000 +/- 500 K and a 1-2% density decrease upon melting, the amount of silicon in the outer core required to match PREM at the CMB is 11.3 +/- 1.5 weight percent, under the simplifying assumption of a purely Fe-Ni-Si outer core. The minimum temperature of an Fe-Si outer core is 4380 K, based on the eutectic melting point of Fe-FeSi alloys, and silicon is shown not to significantly depress the melting point of iron at core conditions. At the highest pressures reached, only the hcp and B2 structures are seen in the Fe-FeSi system. We predict that alloys containing more than ~4-8 wt% Si will convert to an hcp+B2 mixture and later to the hcp structure with increasing pressure, and that an iron-silicon alloy in the Earth's inner core would most likely be a mixture of hcp and B2 phases. [1] Kuwayama and Hirose (2004) Am Mineral 89, 273-276 [2] Morard et al. (2011) PCM 38, 767-776 [3] Lin et al (2002) Science 295, 313-315 [4] Asanuma et al. (2010) PCM 37, 353-359 [5] Lord et al. (2010) JGR 115, B06208 [6] Dewaele et al. (2006) PRL 97, 215504

Fischer, R. A.; Campbell, A. J.; Reaman, D. M.; Heinz, D. L.; Dera, P. K.; Prakapenka, V.

2012-12-01

175

Metal-silicate partitioning of Mo and W at high pressures and temperatures: Evidence for late accretion of sulphur to the Earth  

Science.gov (United States)

In order to place better constraints on the conditions of core formation on Earth and other planetary bodies we have performed experiments to determine the partitioning of Mo and W between liquid Fe-rich metal and liquid silicate at pressures of 1.5-24 GPa and temperatures of 1803-2723 K. Experiments performed in MgO capsules at 1.5 GPa/1923 K indicate that Mo is in the +4 oxidation state in the silicate at oxygen fugacities >2 log units below the IW (Fe-FeO) buffer. In contrast W6+ is the dominant tungsten oxidation state in the silicate at 1.5 GPa/1923 K and 1.8-3.3 log units below the IW buffer. When our 15 data for pressures between 6 and 24 GPa are combined with those of Cottrell et al. (2009) we find evidence neither for a change in oxidation state of W above 6 GPa nor for a change in pressure dependence of partitioning in the experimental fO2 range. Metal-silicate partitioning of both Mo and W shows strong dependence on silicate melt composition with both elements becoming more siderophile as the melt becomes more SiO2-rich. Although the trends in the partitioning data can be related to silicate melt composition in terms of the ratio of nonbridging oxygens to tetrahedral cations {NBO}/{T} we find that use of a regular solution model for the silicate melt results in a significantly better fit to the data. We combined our results with those in the literature to obtain partitioning equations applicable to the Earth. In terms of weight partitioning we define Diwt and (KDi) as follows: (DMowt)={[Mo]}/{[Mo]};(DFewt)={[Fe]}/{[Fe]};(KDMo)={(D}/{Mowt)(DFewt)2};(KDW)={(D}/{Wwt)(DFewt)3} The experimental data, when corrected for compositional effects, yield the following expressions for a pyrolite mantle: log(KDMo)=1.44-{143}/{T}- 167PT (0.19) log(KDW)=1.85-{6728}/{T}- 77PT (0.24) The value in brackets corresponds to 1 standard error of the fit. These expressions were combined with the continuous accretion model of Wade and Wood (2005) to investigate the constraints which they place on the accretionary process. We find, however, that, for accretionary paths consistent with the silicate Earth contents of Ni, Co, V, Cr and Nb, W should partition twice as strongly into the core as Mo. This is in stark contrast to the estimated core-mantle partition coefficients of ˜40 for W and 90-140 for Mo. Neither changes to the accretionary path nor the assumption of partial disequilibrium can readily alter this result. The answer appears to reside with the identity of one of the light elements in the core. We investigated the effect of S on our accretionary model by adding 2% of this element (consistent with cosmochemical estimates) to the core. If S is added at constant S/Fe ratio throughout accretion the net effect is negligible. If, however, S is added exclusively during the last 10-20% of accretion DMo and DW become consistent with the silicate Earth contents of these elements. Only small additional adjustments to the model are required to accommodate changes in partitioning of Ni, Co, V, Cr and Nb. We conclude that the Mo and W contents of the silicate Earth indicate that S (and other moderately volatile elements) was added to the Earth during core formation but only during the last ˜20% of accretion. This conclusion is the same as that reached by Schönbächler et al. (2010) from the Ag isotopic composition of silicate Earth.

Wade, Jon; Wood, Bernard J.; Tuff, James

2012-05-01

176

Carbonate stability in the earth's mantle - A vibrational spectroscopic study of aragonite and dolomite at high pressures and temperatures  

Science.gov (United States)

The structural changes of aragonite and dolomite taking place at high pressures and temperatures were investigated by measuring the Raman spectra of these materials to pressures of 23 and 28 GPa (generated in a diamond anvil cell), respectively; in addition, the IR spectra of aragonite were measured to 40 GPa. The spectroscopic data demonstrated that, at 300 K, dolomite and aragonite samples were stable to pressures of 28 and 41 GPa, respectively. No phase transitions were observed following heating of aragonite and dolomite to temperatures of 2000 K and 800 K, respectively. The mode Grueneisen parameters indicate that the carbonate group in these two minerals is relatively insensitive to pressure, with the dominant compaction mechanism being the compression of the Ca and Mg polyhedra.

Kraft, Susan; Knittle, Elise; Williams, Quentin

1991-01-01

177

High pressure and high temperature experimental study on water storage capacity and distribution in the earth upper mantle  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Trace amounts of hydrogen dissolved as defects in nominally anhydrous minerals (NAMs) in the mantle are believed to play a key role in physical and chemical processes in the Earth's upper mantle. Hence the estimation of water storage in mantle phases and solubility mechanisms are important in order to better understand the effect of water. Experimental data on water solubility in NAMs are available for upper mantle minerals such as olivine, pyroxenes and garnet. However, the majority of studi...

Ferot, Anai?s

2011-01-01

178

Coupled orbit-attitude dynamics of high area-to-mass ratio (HAMR) objects: influence of solar radiation pressure, Earth's shadow and the visibility in light curves  

Science.gov (United States)

The orbital and attitude dynamics of uncontrolled Earth orbiting objects are perturbed by a variety of sources. In research, emphasis has been put on operational space vehicles. Operational satellites typically have a relatively compact shape, and hence, a low area-to-mass ratio (AMR), and are in most cases actively or passively attitude stabilized. This enables one to treat the orbit and attitude propagation as decoupled problems, and in many cases the attitude dynamics can be neglected completely. The situation is different for space debris objects, which are in an uncontrolled attitude state. Furthermore, the assumption that a steady-state attitude motion can be averaged over data reduction intervals may no longer be valid. Additionally, a subset of the debris objects have significantly high area-to-mass ratio (HAMR) values, resulting in highly perturbed orbits, e.g. by solar radiation pressure, even if a stable AMR value is assumed. Note, this assumption implies a steady-state attitude such that the average cross-sectional area exposed to the sun is close to constant. Time-varying solar radiation pressure accelerations due to attitude variations will result in un-modeled errors in the state propagation. This work investigates the evolution of the coupled attitude and orbit motion of HAMR objects. Standardized pieces of multilayer insulation (MLI) are simulated in a near geosynchronous orbits. It is assumed that the objects are rigid bodies and are in uncontrolled attitude states. The integrated effects of the Earth gravitational field and solar radiation pressure on the attitude motion are investigated. The light curves that represent the observed brightness variations over time in a specific viewing direction are extracted. A sensor model is utilized to generate light curves with visibility constraints and magnitude uncertainties as observed by a standard ground based telescope. The photometric models will be needed when combining photometric and astrometric observations for estimation of orbit and attitude dynamics of non-resolved space objects.

Früh, Carolin; Kelecy, Thomas M.; Jah, Moriba K.

2013-12-01

179

The role of small-scale ion injections in the buildup of Earth's ring current pressure: Van Allen Probes observations of the 17 March 2013 storm  

Science.gov (United States)

particle transport into the inner magnetosphere during geomagnetic storms is responsible for significant plasma pressure enhancement, which is the driver of large-scale currents that control the global electrodynamics within the magnetosphere-ionosphere system. Therefore, understanding the transport of plasma from the tail deep into the near-Earth magnetosphere, as well as the energization processes associated with this transport, is essential for a comprehensive knowledge of the near-Earth space environment. During the main phase of a geomagnetic storm on 17 March 2013 (minimum Dst ~ -137 nT), the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument on the Van Allen Probes observed frequent, small-scale proton injections deep into the inner nightside magnetosphere in the region L ~ 4 - 6. Although isolated injections have been previously reported inside geosynchronous orbit, the large number of small-scale injections observed in this event suggests that, during geomagnetic storms injections provide a robust mechanism for transporting energetic ions deep into the inner magnetosphere. In order to understand the role that these injections play in the ring current dynamics, we determine the following properties for each injection: (i) associated pressure enhancement, (ii) the time duration of this enhancement, and (iii) the lowest and highest energy channels exhibiting a sharp increase in their intensities. Based on these properties, we estimate the effect of these small-scale injections on the pressure buildup during the storm. We find that this mode of transport could make a substantial contribution to the total energy gain in the storm time inner magnetosphere.

Gkioulidou, Matina; Ukhorskiy, A. Y.; Mitchell, D. G.; Sotirelis, T.; Mauk, B. H.; Lanzerotti, L. J.

2014-09-01

180

Quantifying the role of fire in the Earth system - Part 2: Impact on the net carbon balance of global terrestrial ecosystems for the 20th century  

Science.gov (United States)

Fire is the primary form of terrestrial ecosystem disturbance on a global scale. It affects the net carbon balance of terrestrial ecosystems by emitting carbon directly and immediately into the atmosphere from biomass burning (the fire direct effect), and by changing net ecosystem productivity and land-use carbon loss in post-fire regions due to biomass burning and fire-induced vegetation mortality (the fire indirect effect). Here, we provide the first quantitative assessment of the impact of fire on the net carbon balance of global terrestrial ecosystems during the 20th century, and investigate the roles of fire's direct and indirect effects. This is done by quantifying the difference between the 20th century fire-on and fire-off simulations with the NCAR Community Land Model CLM4.5 (prescribed vegetation cover and uncoupled from the atmospheric model) as a model platform. Results show that fire decreases the net carbon gain of global terrestrial ecosystems by 1.0 Pg C yr-1 averaged across the 20th century, as a result of the fire direct effect (1.9 Pg C yr-1) partly offset by the indirect effect (-0.9 Pg C yr-1). Post-fire regions generally experience decreased carbon gains, which is significant over tropical savannas and some North American and East Asian forests. This decrease is due to the direct effect usually exceeding the indirect effect, while they have similar spatial patterns and opposite sign. The effect of fire on the net carbon balance significantly declines until ?1970 with a trend of 8 Tg C yr-1 due to an increasing indirect effect, and increases subsequently with a trend of 18 Tg C yr-1 due to an increasing direct effect. These results help constrain the global-scale dynamics of fire and the terrestrial carbon cycle.

Li, F.; Bond-Lamberty, B.; Levis, S.

2014-03-01

 
 
 
 
181

Synthesis of Alkaline Earth Diazenides MAEN2 (MAE = Ca, Sr, Ba) by Controlled Thermal Decomposition of Azides under High Pressure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The alkaline earth diazenides MAEN2 with MAE = Ca, Sr and Ba were synthesized by a novel synthetic approach, namely, a controlled decomposition of the corresponding azides in a multianvil press at highpressure/ high-temperature conditions. The crystal structure of hitherto unknown calcium diazenide (space group I4/mmm (no. 139), a = 3.5747(6) Å, c = 5.9844(9) Å, Z = 2, wRp = 0.078) was solved and refined on the basis of powder X-ray diffraction data as well as that of SrN2 and BaN2. Accordi...

Schneider, Sebastian B.; Frankovsky, Rainer; Schnick, Wolfgang

2012-01-01

182

Fault-related-folding structure and reflection seismic sections. Construction of earth model using balanced cross section; Danso ga kaizaisuru shukyoku kozo no keitai to jishin tansa danmen. 1. Balanced cross section wo mochiita chika model no kochiku  

Energy Technology Data Exchange (ETDEWEB)

Pre-stacking depth migration treatment is studied for the estimation of the fold configuration from seismic survey cross sections. The estimation of a velocity structure is necessary for the execution of such treatment, and the utilization of structural-geological knowledge is required for its interpretation. The concept of balanced cross section in relation to the fault-bend fold constructs a stratum structure model under conditions that the deformation during fold and fault formation is a planar strain, that there is no change in volume due to deformation, and that a fold is a parallel fold. In addition to the above geometric and kinetic approach, there is another fold formation process simulation model using a Newtonian fluid for study from the viewpoint of dynamics. This simulation stands on the presumption that the boundary contains a ramp that had been in presence before fold formation and that an incompressible viscous matter is mounted on the top surface. The viscous matter flows and deforms for the formation of an anticline on the ramp. Such enables the reproduction of a fault-bend fold formation process, and helpful discussion may be furthered on the dynamic aspect of this simulation. 5 refs., 4 figs.

Matsuoka, T.; Tamagawa, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Tsukui, R. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

1997-05-27

183

Structural, electronic, elastic and high-pressure properties of some alkaline-earth chalcogenides: An ab initio study  

International Nuclear Information System (INIS)

The full-potential linearized augmented plane wave method (FP-LAPW) within the generalized gradient approximation (GGA) is used to calculate the electronic band structures and the total energies of BaS, CaSe and CaTe in NaCl and CsCl-type structures. The latter provide us with the ground states properties such as lattice parameter, bulk modulus and its pressure derivative, elastic constants and the structural phase stability of these compounds. The transition pressures at which these compounds undergo the structural phase transition from NaCl to CsCl phase are calculated. The energy band gaps and their volume dependence in NaCl and CsCl type-structures are investigated. The pressure and the volume at which band overlap metallization occurs are also determined. The ground state properties, the transition and metallization pressures (volumes) are found to agree with the experimental and other theoretical results. The elastic constants at equilibrium in both NaCl and CsCl structures are calculated and compared with the available theoretical results for CaSe, while for BaS and CaTe the elastic constants are not available

184

Number Balance  

Science.gov (United States)

This activity promotes algebraic thinking of equivalency as well as giving children practice in addition and subtraction. Students see weights on each side of a balance, and are asked to find ways they can hang a weight or two weights to balance the bar. An interactive balance allows student to explore the different ways weights can be added to balance or equalize the bars. A more challenging problem,"Getting the Balance" is cataloged separately. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support.

2006-01-01

185

Low pressure ion chromatography with a low cost paired emitter-detector diode based detector for the determination of alkaline earth metals in water samples  

International Nuclear Information System (INIS)

The use of a low pressure ion chromatograph based upon short (25 mm x 4.6 mm) surfactant coated monolithic columns and a low cost paired emitter-detector diode (PEDD) based detector, for the determination of alkaline earth metals in aqueous matrices is presented. The system was applied to the separation of magnesium, calcium, strontium and barium in less than 7 min using a 0.15 M KCl mobile phase at pH 3, with post-column reaction detection at 570 nm using o-cresolphthalein complexone. A comparison of the performance of the PEDD detector with a standard laboratory absorbance detector is shown, with limits of detection for magnesium and calcium using the low cost PEDD detector equal to 0.16 and 0.23 mg L-1, respectively. Finally, the developed system was used for the determination of calcium and magnesium in a commercial spring water sample

186

The effect of compression on Individual Pressure Vessel Nickel/Hydrogen components. [for energy storage in low earth orbits  

Science.gov (United States)

Compression tests were performed on representative Individual Pressure Vessel (IPV) Nickel/Hydrogen cell components in an effort to better understand the effects of force on component compression and the interactions of components under compression. It appears that the separator is the most easily compressed of all of the stack components. It will typically partially compress before any of the other components begin to compress. The compression characteristics of the cell components in assembly differed considerably from what would be predicted based on individual compression characteristics. Component interactions played a significant role in the stack response to compression. The results of the compression tests were factored into the design and selection of Belleville washers added to the cell stack to accommodate nickel electrode expansion while keeping the pressure on the stack within a reasonable range of the original preset.

Manzo, Michelle A.; Perez-Davis, Marla E.

1988-01-01

187

Pressure Dependence of Elastic Wave Velocity for beta-Mg2SiO4 and the Composition of the Earth's Mantle.  

Science.gov (United States)

The pressure dependence of the elastic wave velocities for hot-pressed, elastically isotropic polycrystals of the beta (modified spinel) phase of magnesium orthosilicate (Mg(2)SiO(4)) has been determined at room temperature to 3 gigapascals (GPa) by ultrasonic pulse interferometry. Pressure derivatives of the bulk (dK/dP = 4.8) and shear (dG/dP = 1.7) moduli derived from the travel times of the compressional (P) and shear (S) waves clearly demonstrate that the velocity contrast between the olivine and beta phases of Mg(2)SiO(4) decreases with increasing pressure. When combined with plausible values for the (as yet unmeasured) temperature derivatives, these new data can be used to calculate the contrast in P and S wave velocities across an olivine-beta phase transformation occuaring at pressure-temperature conditions corresponding to about 400 kilometers depth in the earth. The seismologically observed contrasts DeltaV in both P and S wave velocities constrain the percentage of orthosilicate in a model mantle of uniform chemical composition for appropriate relative magnitudes of the temperature (T) derivatives of the bulk and shear moduli for the beta phase. Allowed combinations of orthosilicate content (percent), dK/dT, and dG/dT (both in gigapascals per Kelvin) for a pair of recent seismological models with DeltaV(p) = DeltaV(s) 4.6% include (65, -0.018, -0.020), (55, -0.015, -0.018), and (45, -0.012, -0.016). PMID:17759972

Gwanmesia, G D; Rigden, S; Jackson, I; Liebermann, R C

1990-11-01

188

Growth of Carnobacterium spp. from permafrost under low pressure, temperature, and anoxic atmosphere has implications for Earth microbes on Mars.  

Science.gov (United States)

The ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration. Because most water on present-day Mars is frozen in the regolith, permafrosts are considered to be terrestrial analogs of the martian subsurface environment. Six bacterial isolates were obtained from a permafrost borehole in northeastern Siberia capable of growth under conditions of low temperature (0 °C), low pressure (7 mbar), and a CO(2)-enriched anoxic atmosphere. By 16S ribosomal DNA analysis, all six permafrost isolates were identified as species of the genus Carnobacterium, most closely related to C. inhibens (five isolates) and C. viridans (one isolate). Quantitative growth assays demonstrated that the six permafrost isolates, as well as nine type species of Carnobacterium (C. alterfunditum, C. divergens, C. funditum, C. gallinarum, C. inhibens, C. maltaromaticum, C. mobile, C. pleistocenium, and C. viridans) were all capable of growth under cold, low-pressure, anoxic conditions, thus extending the low-pressure extreme at which life can function. PMID:23267097

Nicholson, Wayne L; Krivushin, Kirill; Gilichinsky, David; Schuerger, Andrew C

2013-01-01

189

Tunnel construction work under high earth pressure and springwater flouing condition. Construction details of a pioneer drift for Hida tunnel, Tokai-Hokuriku expressway  

International Nuclear Information System (INIS)

Tunnels such as those planned for the International Linear Collider (ILC) Project are long and narrow structures under the ground. In the construction of these tunnels, various circumstances sometimes restrict the initial surveys from obtaining detailed geological information. In Japan, complicated geological structure composed of discontinuous plate tectonics can be found. Therefore, in order to ensure effective construction planning and execution, it is important that precise geological information be acquired through initial survey and then verified with investigation results during the construction. Hida Tunnel of Tokai Hokuriku Expressway, which is 10.7 km long and took more than 11 years to finish, is the second longest highway tunnel in Japan. The tunnel was constructed using the TBM method in the beginning. Later the method was replaced with NATM because of hostile construction conditions, which include existences of springwater and massive earth pressure due to more than 1000 m of earth loading on top, as well as weak zones consisted of active faults. This paper reports on the geological structure and construction details of a pioneer drift for Hida Tunnel, which was completed by overcoming complicated and poor geological conditions. At the same time, we will mention the ideal method of the geological survey in future ILC plan. (author)

190

Phase relations and sound velocity measurements of iron-sulfur systems at high pressure: implications for the Earth's inner core  

Science.gov (United States)

The sound velocity is one of the most important physical properties which can be assessed by seismology. In spite of its importance, the technical difficulty provides limitation of the measurements under the core conditions. Here we show the results of measurements of the sound velocity of hcp-iron, Fe3S, and FeH by the inelastic X-ray scattering (IXS) method using DAC at high pressure and temperature. Inelastic X-ray scattering spectra were taken at BL35XU, Spring-8. We made the measurements of hcp-iron at pressures up to 180 GPa at room temperature, which is the highest pressure for the IXS measurement. Sound velocity measurements at high pressure and temperature were made up to 91 GPa at 700 K, and to 62 GPa and 1000 K using the external heating diamond anvil cell. The present results revealed that there is almost no temperature effect on the sound velocity of hcp-Fe at least up to 1000 K. We also measured the sound velocity and density of Fe3S up to 85 GPa at room temperature, and clarified the effect of sulfur and hydrogen on the sound velocity of iron at high pressure. Phase relations of the Fe-S (Kamada et al., 2010; 2012) and Fe-S-O systems (Terasaki et al., 2011) were studied up to the core pressures based on the laser heated diamond anvil cell combined with the in situ synchrotron X-ray diffraction at SPring-8. Fe3S dissolves first at the solidus before melting of FeO and metallic iron alloy at the liquidus of the systems up to 180 GPa. The maximum solubility of sulfur in hcp-iron approaches to about 7.5 at % at 86 GPa and 8 at % at 123 GPa, and it does not increase so much at higher pressures. The temperature at ICB based on the extrapolation of the liquidus and solidus temperatures of the outer core composition in the Fe-S-O is about 4360-5630 K assuming that the outer core composition is Fe75O5S20 in the atomic ratio. The temperature at the core-mantle boundary will be 3340-4300 K by the adiabatic decompression from the temperature at the inner core boundary. The CMB temperature is consistent with that derived by the recent geodynamic model (Glisovic, Forte, Moucha, 2012). Based on the phase relations and the sound velocity measurements, we argued the chemical compositions of the outer and inner cores which can account for the density and sound velocity of the core. The presence of Fe3S in the inner core may be a cause of the hemispherical heterogeneity of the inner core.

Ohtani, E.; Kamada, S.; Sakai, T.; Terasaki, H.; Shibazaki, Y.; Sakamaki, T.; Takahashi, S.; Sakairi, T.; Fukui, H.; Baron, A. Q.

2012-12-01

191

`Galileo Galilei' (GG) small-satellite project: an alternative to the torsion balance for testing the equivalence principle on Earth and in space  

Science.gov (United States)

`Galileo Galilei' (GG) is a proposal for a small, low-orbit satellite devoted to testing the equivalence principle (EP) of Galileo, Newton and Einstein. The GG report on the phase A study recently carried out with funding from ASI (Agenzia Spaziale Italiana) concluded that GG can test the equivalence principle to 1 part in 1017 at room temperature. The main novelty is to modulate the expected differential signal of an EP violation at the spin rate of the spacecraft (2 Hz). Compared with other experiments, the modulation frequency is increased by more than a factor of 104, thus reducing 1/f (low-frequency) electronic and mechanical noise. The challenge for an EP test in space is to improve over the sensitivity of ground-based experiments (about 1 part in 1012) by many orders of magnitude, so as to deeply probe a so far totally unexplored field; doing that with more than one pair of bodies is an unnecessary complication. For this reason GG is now proposed with a single pair of test masses. At present the best and most reliable laboratory-controlled tests of the equivalence principle have been achieved by the `Eöt-Wash' group with small test cylinders arranged on a torsion balance placed on a turntable which provides the modulation of the signal (a 1-2 h rotation period). The torsion balance is not a suitable instrument in space. We have designed and built the GGG (`GG on the Ground') prototype. It is made of coaxial test cylinders weakly coupled (via mechanical suspensions) and quickly rotating (6 Hz achieved so far); in addition, it is well suited to be flown in space - where the driving signal is about three orders of magnitude stronger and the absence of weight is very helpful - inside the coaxial, co-rotating GG cylindrical spacecraft. The GGG apparatus is now operational. Preliminary measurement data indicate that weakly coupled, fast-spinning macroscopic rotors can be a suitable instrument to detect small differential effects. Rotation (up to 6 Hz so far) is stabilized by a small passive oil damper. A finer active damper, using small capacitance sensors and actuators as in the design of the space experiment, is in preparation. The current sensitivity of the GGG system is of 10-9 m s-2/?Hz at about 300 s, which can be improved because horizontal seismic noise is rejected very well; perturbing effects of terrain tilts (due to microseismicity and tides) will be reduced by adding a passive cardanic suspension. As for the capacitance read-out, the current sensitivity (5 pm displacements in 1 s integration time at room temperature) is adequate to make GGG competitive with the torsion balance. Because of the stronger signal and weaker coupling of the test rotors in space, this sensitivity is also adequate for GG to reach its target accuracy (10-17). Information, references, research papers and photographs of the apparatus are available on the Web (http://tycho.dm.unipi.it/nobili).

Nobili, A. M.; Bramanti, D.; Polacco, E.; Roxburgh, I. W.; Comandi, G.; Catastini, G.

2000-06-01

192

Synthesis of alkaline earth diazenides M(AE)N2 (M(AE) = Ca, Sr, Ba) by controlled thermal decomposition of azides under high pressure.  

Science.gov (United States)

The alkaline earth diazenides M(AE)N(2) with M(AE) = Ca, Sr and Ba were synthesized by a novel synthetic approach, namely, a controlled decomposition of the corresponding azides in a multianvil press at high-pressure/high-temperature conditions. The crystal structure of hitherto unknown calcium diazenide (space group I4/mmm (no. 139), a = 3.5747(6) Å, c = 5.9844(9) Å, Z = 2, wR(p) = 0.078) was solved and refined on the basis of powder X-ray diffraction data as well as that of SrN(2) and BaN(2). Accordingly, CaN(2) is isotypic with SrN(2) (space group I4/mmm (no. 139), a = 3.8054(2) Å, c = 6.8961(4) Å, Z = 2, wR(p) = 0.057) and the corresponding alkaline earth acetylenides (M(AE)C(2)) crystallizing in a tetragonally distorted NaCl structure type. In accordance with literature data, BaN(2) adopts a more distorted structure in space group C2/c (no. 15) with a = 7.1608(4) Å, b = 4.3776(3) Å, c = 7.2188(4) Å, ? = 104.9679(33)°, Z = 4 and wR(p) = 0.049). The N-N bond lengths of 1.202(4) Å in CaN(2) (SrN(2) 1.239(4) Å, BaN(2) 1.23(2) Å) correspond well with a double-bonded dinitrogen unit confirming a diazenide ion [N(2)](2-). Temperature-dependent in situ powder X-ray diffractometry of the three alkaline earth diazenides resulted in formation of the corresponding subnitrides M(AE(2))N (M(AE) = Ca, Sr, Ba) at higher temperatures. FTIR spectroscopy revealed a band at about 1380 cm(-1) assigned to the N-N stretching vibration of the diazenide unit. Electronic structure calculations support the metallic character of alkaline earth diazenides. PMID:22235865

Schneider, Sebastian B; Frankovsky, Rainer; Schnick, Wolfgang

2012-02-20

193

Integration of Infrasound, Atmospheric Pressure, and Seismic Observations with the NSF EarthScope USArray Transportable Array  

Science.gov (United States)

Earthscope's USArray Transportable Array (TA) network serves as a real-time monitoring and recording platform for both seismic and weather phenomena. To date, most of the approximately 500 TA stations have been retrofitted with VTI SCP1000 MEMS barometric pressure gauges capable of recording data at 1 sample per second (sps). Additionally, over 300 of the TA stations have also been retrofitted with Setra 278 barometric gauges and NCPA infrasound sensors capable of recording data at 1 and 40 sps. While individual seismic events have been successfully researched via the TA network, observations of powerful weather events by the TA network have yet to be embraced by the scientific community. This presentation will focus on case studies involving severe weather passage across portions of the TA network throughout 2011 in order to highlight its viability as a platform for real-time weather monitoring and research. It will also highlight the coupling of atmospheric signals into the seismic observations. Examples of gust front passages and pressure couplets from severe thunderstorms will be presented, as will observations of multiple tornados occurred in the Spring of 2011. These data will demonstrate the overall viability of the TA network for monitoring severe weather events in real-time.

Vernon, F.; Tytell, J.; Hedlin, M. A. H.; Walker, K.; Busby, R.; Woodward, R.

2012-04-01

194

Indoor seismology by probing the Earth's interior by using sound velocity measurements at high pressures and temperatures  

International Nuclear Information System (INIS)

The adiabatic bulk (K S) and shear (G) moduli of mantle materials at high pressure and temperature can be obtained directly by measuring compressional and shear wave velocities in the laboratory with experimental techniques based on physical acoustics. We present the application of the current state-of-the-art experimental techniques by using ultrasonic interferometry in conjunction with synchrotron x radiation to study the elasticity of olivine and pyroxenes and their high-pressure phases. By using these updated thermoelasticity data for these phases, velocity and density profiles for a pyrolite model are constructed and compared with radial seismic models. We conclude that pyrolite provides an adequate explanation of the major seismic discontinuities at 410- and 660-km depths, the gradient in the transition zone, as well as the velocities in the lower mantle, if the uncertainties in the modeling and the variations in different seismic models are considered. The characteristics of the seismic scaling factors in response to thermal anomalies suggest that anticorrelations between bulk sound and shear wave velocities, as well as the large positive density anomalies observed in the lower mantle, cannot be explained fully without invoking chemical variations

195

Deformation of polyphase aggregates, forsterite+MgO, at pressures and temperatures of the Earth's upper mantle  

Science.gov (United States)

Modelling the solid-state flow of the upper mantle requires a thorough understanding of its rheology and therefore necessitates to perform deformation experiments on mantle rocks (or analogues) at very high pressures and temperatures. Minerals other than olivine constitute up to 40 vol% of upper mantle rocks and may have a significant effect on the rheological behavior of these rocks. Nevertheless, most experimental studies to date have focused on the deformation properties of olivine single crystals or monomineralic olivine aggregates. In this study, and as a first step before focusing on more realistic mantle-like compositions, we have performed deformation experiments on polymineralic model aggregates of forsterite and MgO, at upper mantle pressures and temperatures. Commercial powders of Mg2SiO4 and MgO were mixed and ground in WC grinders and dried in a one-atmosphere furnace at 1000°C. Powders with different volume proportions of the two phases were sintered by spark plasma sintering (SPS) at temperatures of 1300-1400°C and 100 MPa for a few minutes, resulting in dense pellets 8 mm in diameter and 3-4 mm in length. Microstructural analysis by SEM reveals equilibrated microstructures with forsterite and MgO grain sizes of a few microns. Deformation experiments on samples 1.2 mm in diameter and 1.2 mm in length were performed at 3-8 GPa and 1000-1300°C in a D-DIA apparatus coupled with synchrotron X-ray radiation. The technique permits in situ measurement of macroscopic strain rates as well as stress levels sustained by different subpopulations of grains of each phase. Typically, two specimens, respectively a monomineralic and a polyphase aggregate, were deformed concurrently in order to minimize the relative uncertainties in temperature and pressure and to facilitate the comparison of their rheological properties. The samples were deformed to total strains of 15-25%. As expected, the harder phase, forsterite, sustains much higher stress levels than MgO, in agreement with numerical models for two-phase flow. Results on stress and strain partitioning in polyphase aggregates and on the effect of the presence of a weak phase on the rheology of forsterite-rich aggregates will be discussed.

Bejina, F.; Bystricky, M.; Ingrin, J.

2012-12-01

196

Microstructual investigation of mixed rar earth iron boron processed vis melt-spinning and high-pressure gas-atomization for isotrophic bonded permanent magnets  

Energy Technology Data Exchange (ETDEWEB)

A solid solution of three rare earths (RE) in the RE{sub 2}Fe{sub 14}B structure have been combined to create the novel mixed rare earth iron boron (MRE{sub 2}Fe{sub 14}B) alloy family. MRE{sub 2}Fe{sub 14}B exhibits reduced temperature dependent magnetic properties; remanence and coercivity. The desired form of MRE{sub 2}Fe{sub 14}B is a powder that can be blended with a polymer binder and compression or injection molded to form an isotropic polymer bonded permanent magnet (PBM). Commercially, Nd{sub 2}Fe{sub 14}B is the alloy of choice for PBMs. Powders of Nd{sub 2}Fe{sub 14}B are made via melt-spinning as can be MRE{sub 2}Fe{sub 14}B which allows for direct comparisons. MRE{sub 2}Fe{sub 14}B made using melt-spinning at high wheel speeds is overquenched and must be annealed to an optimal hard magnetic state. Due to the rare earth content in the MRE{sub 2}Fe{sub 14}B powders, they must be protected from the environment in which they operate. This protection is accomplished by using a modified fluidized bed process to grow a protective fluoride coating nominally 15nm thick, to reduce air oxidation. MRE{sub 2}Fe{sub 14}B has demonstrated reduced temperature dependent magnetic properties in ribbon and PBM form. The real challenge has been modifying alloy designs that were successfully melt-spun to be compatible with high-pressure gas-atomization (HPGA). The cooling rates in HPGA are lower than melt-spinning, as the powders are quenched via convective cooling, compared to melt-spinning, which quenches initially by conductive cooling. Early alloy designs, in gas atomized and melt-spun form, did not have similar phase compositions or microstructures. Alloy additions, such as the addition of zirconium as a nucleation catalyst, were successful in creating similar phases and microstructures in the HPGA powders and melt-spun ribbon of the same MRE{sub 2}Fe{sub 14}B composition.

Buelow, Nicholas Lee

2005-08-01

197

Formulation of high-precision volume-of-fluid method establishing appropriate balance between pressure and surface tension and its application to gas entrainment phenomena in fast breeder reactors  

International Nuclear Information System (INIS)

To evaluate directly gas entrainment (GE) phenomena in fast reactors, a numerical simulation method based on a high-precision volume-of-fluid (VOF) methodology have been studied. Unstructured meshes to subdivide simulation domains have been employed because exact modeling of complicated geometries is necessary for GE simulations. In this note, formulations of each calculation procedure in the high-precision VOF methodology on unstructured meshes are briefly presented. Calculation procedures of surface tension forces are also presented. In addition, unphysical behaviors of velocity distributions near gas-liquid interface induced by inappropriate formulation of pressure gradient are addressed and an appropriate formulation is presented considering proper balance conditions between pressure and surface tension forces. Finally, the improved simulation method is applied to the basic GE experiment. The simulation results show that the GE phenomena occur in the same mechanism with the experimental results. (author)

198

Balancing Acts  

Science.gov (United States)

... a new type of balance therapy using computerized, virtual reality. UPMC associate professor Susan Whitney, Ph.D., developed ... a virtual grocery store in the university's Medical Virtual Reality Center. Patients walk on a treadmill and safely ...

199

Coupled Orbit-Attitude Dynamics of High Area-to-Mass Ratio (HAMR) Objects: Influence of Solar Radiation Pressure, Earth's Shadow and the Visibility in Light Curves  

CERN Document Server

The orbital and attitude dynamics of uncontrolled Earth orbiting objects are perturbed by a variety of sources. In research, emphasis has been put on operational space vehicles. Operational satellites typically have a relatively compact shape, and hence, a low area-to-mass ratio (AMR), and are in most cases actively or passively attitude stabilized. This enables one to treat the orbit and attitude propagation as decoupled problems, and in many cases the attitude dynamics can be neglected completely. The situation is different for space debris objects, which are in an uncontrolled attitude state. Furthermore, the assumption that a steady-state attitude motion can be averaged over data reduction intervals may no longer be valid. Additionally, a subset of the debris objects have significantly high area-to-mass ratio values, resulting in highly perturbed orbits, e.g. by solar radiation pressure, even if a stable AMR value is assumed. This assumption implies a steady-state attitude such that the average cross-sect...

Frueh, Carolin; Kelecy, Thomas

2013-01-01

200

High-pressure synthesis and characterization of the rare-earth fluoride borate LaB{sub 2}O{sub 4}F  

Energy Technology Data Exchange (ETDEWEB)

The rare-earth fluoride borate LaB{sub 2}O{sub 4}F was synthesized under high-pressure/high-temperature conditions of 1.1 GPa and 1300 C in a Walker-type multianvil apparatus from lanthanum oxide, lanthanum fluoride, and boron oxide. The single-crystal structure determination revealed that LaB{sub 2}O{sub 4}F is isotypic to CeB{sub 2}O{sub 4}F. The compound crystallizes in the orthorhombic space group Pbca (no. 61) with eight formula units and the lattice parameters a = 8.2493(9), b = 12.6464(6), c = 7.3301(5) A, V = 764.7(2) A{sup 3}, R{sub 1} = 0.0354, and wR{sub 2} = 0.0474 (all data). The structure exhibits a 9+1 coordinated lanthanum cation, one threefold coordinated fluoride ion and a chain of corner-sharing [BO{sub 3}]{sup 3-} groups. In addition to the IR- and Raman-spectroscopic investigations, DFT calculations were performed to support the assignment of the vibrational bands. (orig.)

Hinteregger, Ernst; Kocsis, Krisztina; Hofer, Thomas S.; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Perfler, Lukas [Innsbruck Univ. (Austria). Inst. fuer Mineralogie und Petrographie

2013-09-15

 
 
 
 
201

Estudo da sinterização da zircônia dopada com óxidos de terras raras a 5 GPa de pressão / Sintering of rare earth-doped zirconia under 5 GPa pressure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A zircônia (ZrO2) tem mostrado grande destaque entre as cerâmicas avançadas, atraindo muito o interesse de pesquisadores em seus vários campos de atuação. A zircônia apresenta elevada resistência quando na fase tetragonal, mas a fase estável a temperatura ambiente é a monoclínica, sendo necessário o [...] uso de estabilizantes para a fase tetragonal. Neste trabalho propomos a sinterização rápida da zircônia parcialmente estabilizada com óxidos de terras raras (ZrO2-OTR), mediante o emprego da alta pressão de 5 GPa. As condições de sinterização realizadas neste trabalho são inovadoras, haja visto que utilizou-se de tecnologia alternativa para processar a ZrO2-OTR, chamada de altas temperaturas e altas pressões (HPHT). Foi utilizada uma pressão de 5 GPa, temperaturas de 1100, 1200 e 1300 ºC nos tempos de 2 e 5 min. O melhor resultado foi obtido nas amostras sinterizadas a 5 GPa/1300 ºC/5 min, onde apresentaram microdureza média de 488,73 kgf/mm², para uma tenacidade à fratura de 5,33 MPa.m½, as quais apresentaram densidade da ordem de 97,88% da teórica, e 88% em volume de fase tetragonal retida à temperatura ambiente. Abstract in english Zirconia (ZrO2) has shown great projection among the advanced ceramics, attracting the interest of researchers in its various fields of application. Tetragonal zirconia presents high mechanical strength, but the room temperature stable phase is the monoclinic, being necessary the use of stabilizers [...] for obtaining the tetragonal phase. In this work the rapid sintering of zirconia partially stabilized with rare earth oxides (ZrO2-OTR), via 5 GPa high pressure is proposed. The sintering conditions employed in this work are innovative, due to the use of an alternative technology to process ZrO2-OTR, so called high temperature - high pressure (HPHT). A pressure of 5 GPa and temperatures of 1100, 1200 and 1300 ºC for times of 2 and 5 min were used. The best results were obtained for samples sintered at 5 GPa at 1300 ºC/5 min., where a micro-hardness of 488,73 kgf/mm², a fracture toughness of 5,33 MPa.m½, a density of 97,88%, and a 88vol.% of tetragonal phase retained at room temperature were achieved.

C., Kuranaga; F. S. de Azevedo, Ribeiro; M., Filgueira.

2005-06-01

202

Chaotic behavior in a system simulating the pressure balanced injection system. Analysis of passive safety reactor behavior. JAERI's nuclear research promotion program, H12-012 (Contract research)  

Energy Technology Data Exchange (ETDEWEB)

The pressure Balanced Injection System (PBIS) was proposed in a passive safety reactor. Pressurizing Line (PL) connects the Reactor Vessel (RV) and the gas area in the Contain Vessel (CV), and Injected Line (IL) connects two vessels at relatively lower position. In an accident, the two lines are passively opened. The vapor generated by the residual heat pressed downward the water level in the RV. When the level is lower than the inlet of the PL, vapor is ejected into the CV through the PL attaining the pressure balance between the vessels. Then boron water in the CV is injected into the RV through the IL by the static head. This process is repeated by the succeeding vapor generation. In an experiment, the oscillating system was replaced by water column in a U-shaped duct. The vapor generation was simulated by cover gas supply to one end of the duct, while the other end was open to the atmosphere. When the water level reached a certain level, electromagnetic valves opened and the cover gas was ejected. The gas pressure decreased rapidly, resulting in a surface rise. When the water level reached another level, the valves closed. The cover gas pressure increased again, thus, gas ejection occurred intermittently. The interval of the gas ejection was not constant but fluctuated widely. Mere stochastic noise could hardly explain the large amplitude. Then was expressed the system using a set of linear equations. Various types of piecewise linear model were developed to examine the cause of the fluctuation. There appeared tangential bifurcation, period-doubling bifurcation, period-adding bifurcation and so on. The calculated interval exhibited chaotic features. Thus the cause of the fluctuation can be attributed to chaotic features of the system having switching. Since the piecewise linear model was highly simplified the behavior, a quantitative comparison between the calculation and the experiment was difficult. Therefore, numerical simulation code considering nonlinear effect was developed to describe the system behavior in the case there was no stochastic noise. The comparison between the simulation and the experiment revealed that there are some bifurcation-like phenomena being not real bifurcations. Real bifurcations are discovered in the simulation as well as in the experiment. Confirmation of chaotic behavior of the system in the experiment is a subject for a future study. (author)

Madarame, Haruki; Okamoto, Koji; Tanaka, Gentaro; Morimoto, Yuichiro [Tokyo Univ., School of Engineering, Tokyo (Japan); Sato, Akira [Yamagata Univ., Faculty of Engineering, Yonezawa, Yamagata (Japan); Kondou, Masaya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

203

Earth meandering  

Science.gov (United States)

In this paper we try to put away current Global Tectonic Model to look the tectonic evolution of the earth from new point of view. Our new dynamic model is based on study of river meandering (RM) which infer new concept as Earth meandering(EM). In a universal gravitational field if we consider a clockwise spiral galaxy model rotate above Ninety East Ridge (geotectonic axis GA), this system with applying torsion field (likes geomagnetic field) in side direction from Rocky Mt. (west geotectonic pole WGP) to Tibetan plateau TP (east geotectonic pole EGP),it seems that pulled mass from WGP and pushed it in EGP due to it's rolling dynamics. According to this idea we see in topographic map that North America and Green land like a tongue pulled from Pacific mouth toward TP. Actually this system rolled or meander the earth over itself fractaly from small scale to big scale and what we see in the river meandering and Earth meandering are two faces of one coin. River transport water and sediments from high elevation to lower elevation and also in EM, mass transport from high altitude-Rocky Mt. to lower altitude Himalaya Mt. along 'S' shape geodetic line-optimum path which connect points from high altitude to lower altitude as kind of Euler Elastica(EE). These curves are responsible for mass spreading (source) and mass concentration (sink). In this regard, tiltness of earth spin axis plays an important role, 'S' are part of sigmoidal shape which formed due to intersection of Earth rolling with the Earth glob and actual feature of transform fault and river meandering. Longitudinal profile in mature rivers as a part of 'S' curve also is a kind of EE. 'S' which bound the whole earth is named S-1(S order 1) and cube corresponding to this which represent Earth fracturing in global scale named C-1(cube order 1 or side vergence cube SVC), C-1 is a biggest cycle of spiral polygon, so it is not completely closed and it has separation about diameter of C-7. Inside SVC we introduce cone vergence cube (CVC or geotectonic equator GE) which rotate 45 degree counterclockwise with respect to SVC. Every cube from big scale to small scale fractalize in order of 23 and every '8' shape from big scale to small scale also fractalize in the same order. Three dimensional and fractoscopic imagination about understanding the changing on earth is very important so we should imagine '8' as curved surface, sea floor spreading happened in maximum curvature of these surfaces. '8' formed from pair 'S' string with opposite direction. '8' oscillate in Pole-Pole and Side-Side direction and have saddle geometry with two 'U' path along perpendicular saddle (e.g. Lut/Jazmurian and Helmand/Mashkal basin in Iran actually intersection of this saddle shape with the earth surface and Iceland /Black Sea and CapeVerde/Victoria Lake are also In/Out (small scale polygon) of 'U' shape conduit which followed axial saddle of Side-'S-2' and Okhotsk Sea /Balkhash Lake followed axial saddle conduit of Pole-'S-2' actually intersection of this perpendicular conduit with surface make spot-like-lakes/volcanoes or basin. Global EM in Side-S-1 bounded compression region-TP inside and tension region-East African Rift offside).This is a interesting competing between two kinematic geometry - spherical and isometrical geometry by using the interaction of them we can analyze the earth face in past, present and future apart of the forces that cause this face. C-1 in two dimensional look like six sided big tent which speared over Tibet and main rod driven along GA. Pair S-1 curve. have seven component(fold) and six segment in between,S-7 exactly located on TP(center of S-1). Between two successive fold we have complex geology(e.g. eastern Iran and Afghanistan)mass dragged from North America and Siberian and accumulated gradually during six step in Earth Foundation(Tibet),S-7 bounded Takla Makan Desert (in smaller loop) and TP (in bigger loop) S-7 alter the earth balance and responsible for earth disturbing, another sample of 'S' curve we see around Australia and Kermadec/Tonga Trench, Aleutian ri

Asadiyan, H.; Zamani, A.

2009-04-01

204

Balancing Eggs  

Science.gov (United States)

Theory predicts that an egg-shaped body should rest in stable equilibrium when on its side, balance vertically in metastable equilibrium on its broad end and be completely unstable on its narrow end. A homogeneous solid egg made from wood, clay or plastic behaves in this way, but a real egg will not stand on either end. It is shown that this…

Mills, Allan

2014-01-01

205

High-pressure syntheses and characterization of the rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho)  

Energy Technology Data Exchange (ETDEWEB)

The new rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho) were synthesized under high-pressure/high-temperature conditions of 1.5 GPa/1200 C for Tb{sub 2}(BO{sub 3})F{sub 3} and 3.0 GPa/900 C for Dy{sub 2}(BO{sub 3})F{sub 3} and Ho{sub 2}(BO{sub 3})F{sub 3} in a Walker-type multianvil apparatus from the corresponding rare-earth sesquioxides, rare-earth fluorides, and boron oxide. The single-crystal structure determinations revealed that the new compounds are isotypic to the known rare-earth fluoride borate Gd{sub 2}(BO{sub 3})F{sub 3}. The new rare-earth fluoride borates crystallize in the monoclinic space group P2{sub 1}/c (Z = 8) with the lattice parameters a = 16.296(3), b = 6.197(2), c = 8.338(2) A, {beta} = 93.58(3) for Tb{sub 2}(BO{sub 3})F{sub 3}, a = 16.225(3), b = 6.160(2), c = 8.307(2) A, {beta} = 93.64(3) for Dy{sub 2}(BO{sub 3})F{sub 3}, and a = 16.189(3), b = 6.124(2), c = 8.282(2) A, {beta} = 93.69(3) for Ho{sub 2}(BO{sub 3})F{sub 3}. The four crystallographically different rare-earth cations (CN = 9) are surrounded by oxygen and fluoride anions. All boron atoms form isolated trigonal-planar [BO{sub 3}]{sup 3-} groups. The six crystallographically different fluoride anions are in a nearly planar coordination by three rare-earth cations. (orig.)

Hinteregger, Ernst; Pitscheider, Almut; Wurst, Klaus; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Enders, Michael [Innsbruck Univ. (Austria). Inst. fuer Pharmazie

2013-11-15

206

Stationkeeping of the First Earth-Moon Libration Orbiters: The ARTEMIS Mission  

Science.gov (United States)

Libration point orbits near collinear locations are inherently unstable and must be controlled. For Acceleration Reconnection and Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) Earth-Moon Lissajous orbit operations, stationkeeping is challenging because of short time scales, large orbital eccentricity of the secondary, and solar gravitational and radiation pressure perturbations. ARTEMIS is the first NASA mission continuously controlled at both Earth-Moon L1 and L2 locations and uses a balance of optimization, spacecraft implementation and constraints, and multi-body dynamics. Stationkeeping results are compared to pre-mission research including mode directions.

Folta, David; Woodard, Mark; Cosgrove, D.

2011-01-01

207

Investigation of electron parallel pressure balance in the scrape-off layer of deuterium-based radiative divertor discharges IN DIII-D  

International Nuclear Information System (INIS)

Electron density, temperature, and parallel pressure measurements at several locations along field lines connecting the midplane scrapeoff layer (SOL) with the outer divertor are presented for both attached and partially-detached divertor cases: Ip = 1.4 MA, q95 = 4.2, and Pinput ? 6.7 MW under ELMing H-mode conditions. At the onset of the Partially Detached Divertor (PDD), a high density, low temperature plasma forms in the divertor SOL (divertor MARFE). The electron pressure drops by a factor of ? 2 between the midplane separatrix and the X-point, and then an additional ?3--5 times between the X-point and the outboard separatrix strike point. These results are in contrast to the attached (non-PDD) case, where electron pressure in the SOL is reduced by, at most, a factor of two between the midplane and the divertor target. Divertor MARFEs generally have only marginal adverse impact on important H-mode characteristics, such as confinement time. In fact, PDD discharges at low input power maintains good H-mode characteristics until a high density, low temperature plasma abruptly forms inside the separatrix near the X-point (X-point MARFE). Concurrent with the appearance of this X-point MARFE is a degradation in both energy confinement and the plasma fueling rate, and an increase in the carbon impurity concentration inside the core plasma. The formation of the X-point MARFE is consistent with a thermal instability resulting from the temperature dependence of the carbon radiative cooling rate in the range ? 7--30 eV

208

New high pressure rare earth tantalates RExTa2O5+1.5x (RE=La, Eu, Yb)  

International Nuclear Information System (INIS)

Rare earth tantalates La0.075Ta2O5.113, Eu0.089Ta2O5.134 and Yb0.051Ta2O5.077 have been prepared by solid state reaction at P=7.0 GPa and T=1050–1100 °C and studied by X-ray diffraction, thermal analysis and electron microscopy. Low hydrated amorphous tantalum, lanthanum, europium and ytterbium hydroxides were used as starting materials. Aqueous as well as anhydrous compounds were obtained. Title tantalates are crystallized in the structure type of F–Ta2O5 [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464–471] [5]. The structure was refined by the Rietveld method from X-ray powder diffractometer data: La0.075Ta2O5.113, a=10.5099(2), b=7.2679(1), c=6.9765(1) Å, V=532.90(1) Å3, Z=6, space group Ibam; Eu0.089Ta2O5.134, a=10.4182(3), b=7.2685(1), c=6.9832(1) Å, V=528.80(2) Å3, Z=6, space group Ibam; Yb0.051Ta2O5.077, a=10.4557(2), b=7.3853(1), c=6.8923(1) Å, V=532.21(1) Å3, Z=6, space group Ibam. RE atoms do not replace the tantalum in its positions but the only water in the channels of the structure. Highly charged cations RE+3 compress the unit cell so that its volume becomes less than that of F–Ta2O5. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer. - Graphical abstract: The structure of RExTa2O5+1.5x and its HRTEM image (“A” arrows show empty channel, “B” arrows show filled channel). - Highlights: • We synthesized new tantalates of RE under high pressure high temperature conditions. • RE atoms replace water molecules in the channels of the structure. • Aqueous as well as anhydrous tantalates were obtained. • Highly charged cations RE+3 compress the unit cell decreasing RE–O distances

209

Formation of high-precision volume-of-fluid method establishing appropriate balance between pressure and surface tension and its application to gas entrainment phenomena in fast breeder reactors  

International Nuclear Information System (INIS)

To evaluate directly gas entrainment (GE) phenomena in fast breeders, we have been studied a numerical simulation method based on a high-precision volume-of-fluid (VOF) methodology. In addition, we have been employed unstructured meshes to subdivide simulation domains because exact modeling of complicated geometries in each simulation domain is a key to simulate gas entrainment phenomena accurately. Therefore, as important parts of our study, formulations of each calculation procedure in the high-precision VOF methodology on unstructured meshes are conducted in this paper. In concrete terms, calculation procedures for 1) interfacial gradient vectors, 2) interface reconstructions, 3) fluxes of volume fraction on each mesh cell face are formulated on unstructured meshes. Calculation procedures of Surface tension forces are also formulated in this paper. Then, unphysical behaviors of velocity distributions near gas-liquid interface induced by inappropriate formulation of pressure gradient are discussed and an appropriate formulation is derived considering proper balance conditions between pressure and surface tension forces. It is confirmed that this new formulation reduces the unphysical behaviors in a numerical simulation of a rising gas bubble in liquid. Finally, the basic GE experiment is simulated using our numerical simulation method. The simulation results shows that the GE phenomena occurs in the same mechanism with the experimental results. (author)xperimental results. (author)

210

En Balance  

Science.gov (United States)

Purpose This study was designed to assess the feasibility of culturally and language-sensitive diabetes education as a way to increase physical activity and to improve health/diabetes management in a group of Spanish-speaking Hispanics in the Inland Empire region of Southern California. Methods En Balance is a culturally sensitive diabetes education program designed for Spanish-speaking Hispanic adults. The 3-month educational intervention assessed 16 males and 23 females living in Riverside and San Bernardino counties of Southern California. Baseline and 3-month evaluations of physical activity were assessed using the validated Arizona Activity Frequency Questionnaire. Results After 3 months on the En Balance program, there was a significant increase in moderate intensity physical activity energy expenditure (M = 368 ± 894 kcal/day, P < 0.01) and high intensity physical activity energy expenditure (M = 405 ± 2569 kcal/day, P = 0.05) compared to baseline and significant reductions in A1C (?0.90%, P = 0.01), total cholesterol (?13.44 mg/dl, P = 0.01), LDL cholesterol (?10.28 mg/dl, P = 0.03), and waist circumference (?1.52 cm, P = 0.04). Conclusion En Balance program resulted in significant mean increases in both moderate and high intensity physical activity energy expenditure among this group of Hispanic diabetic participants, indicating that despite a general pattern of low physical activity in this group, an intervention that stresses both nutrition and exercise in culturally sensitive ways can positively impact participant’s physical activity levels as well as impact nutritional changes. PMID:22968219

Wheeler, Gina; Montgomery, Susanne B.; Beeson, Larry; Bahjri, Khaled; Shulz, Eloy; Firek, Anthony; De Leon, Marino; Cordero-MacIntyre, Zaida

2014-01-01

211

Social Balance Theory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We construct a model based on social balance theory proposed by Fritz Heider to analyze the interpersonal network among social agents. The model of social balance theory provides us an interesting tool to see how a social group evolves to the possible balance state. We introduce the balance index that can be used to measure social balance in macro structure level (global balance index) or in micro structure (local balance index) to see how the local balance index influences ...

Khanafiah, Deni; Situngkir, Hokky

2004-01-01

212

Effect of rare earth on lattice size and equilibrium hydrogen pressure for AB5-type MmNi3.55Co0.75Al0.30Mn0.40  

International Nuclear Information System (INIS)

We investigated the effect of rare earth in Mm (misch metal) to crystal structure and hydrogenation properties especially lattice size and equilibrium hydrogen pressure in MmNi3.55Co0.75Al0.30Mn0.40 using X-ray diffraction (XRD) and pressure-composition (P-C) isotherms measurements. We successfully prepared the alloys, where Mm was composed of MxLa0.81-xNd0.14Pr0.05 (Mx = Ce0.47, Y0.40, Gd0.25, Tm0.20, Lu0.16). The substitution amount for each alloy was adjusted to appear stoichiometric single phase and to keep the same lattice volume considering atomic radius of each rare earth element. Among these alloys, however, the Ce containing ones studied showed different characteristics in terms of anisotropy of lattice parameters and equilibrium hydrogen pressure to others. All alloys studied showed the same reversible hydrogen content. Significant difference of the enthalpy and entropy of hydride formation have not been observed

213

Balanced Flow Meters without Moving Parts  

Science.gov (United States)

Balanced flow meters are recent additions to an established class of simple, rugged flow meters that contain no moving parts in contact with flow and are based on measurement of pressure drops across objects placed in flow paths. These flow meters are highly accurate, minimally intrusive, easily manufacturable, and reliable. A balanced flow meter can be easily mounted in a flow path by bolting it between conventional pipe flanges. A balanced flow meter can be used to measure the flow of any of a variety of liquids or gases, provided that it has been properly calibrated. Relative to the standard orifice-plate flow meter, the balanced flow meter introduces less turbulence and two times less permanent pressure loss and is therefore capable of offering 10 times greater accuracy and repeatability with less dissipation of energy. A secondary benefit of the reduction of turbulence is the reduction of vibration and up to 15 times less acoustic noise generation. Both the balanced flow meter and the standard orifice-plate flow meter are basically disks that contain holes and are instrumented with pressure transducers on their upstream and downstream faces. The most obvious difference between them is that the standard orifice plate contains a single, central hole while the balanced flow meter contains multiple holes. The term 'balanced' signifies that in designing the meter, the sizes and locations of the holes are determined in an optimization procedure that involves balancing of numerous factors, including volumetric flow, mass flow, dynamic pressure, kinetic energy, all in an effort to minimize such undesired effects as turbulence, pressure loss, dissipation of kinetic energy, and non-repeatability and nonlinearity of response over the anticipated range of flow conditions. Due to proper balancing of these factors, recent testing demonstrated that the balanced flow-meter performance was similar to a Venturi tube in both accuracy and pressure recovery, but featured reduced cost and pipe-length requirements.

Kelley, Anthony R.; VanBuskirk, Paul

2008-01-01

214

Dynamical balance in the Indonesian Seas circulation  

Science.gov (United States)

A high resolution, four-open port, non-linear, barotropic ocean model (2D POM) is used to analyze the Indonesian Seas circulation. Both local and overall momentum balances are studied. It is shown that geostrophy holds over most of the area and that the Pacific-Indian Ocean pressure difference is essentially balanced by the resultant of pressure forces acting on the bottom.

Burnett, William H.; Kamenkovich, Vladimir M.; Jaffe, David A.; Gordon, Arnold L.; Mellor, George L.

2000-09-01

215

First-Principles Studies of Pressure-Induced Structural and Insulator-To Transitions in Alkaline-Earth Dicarbides MC2 (M = Ca, Sr and Ba)  

Science.gov (United States)

Pressure-induced phase transitions in MC2 (M = Ca, Sr and Ba) are investigated by using the first-principles plane wave pseudopotential method within the generalized gradient approximation. The first-order phase transition from tetragonal phase (CaC2-type, space group I4/mmm) to rhombohedral (CsCl-type, space group R/line{3}m) structure is predicted to occur at 22.2, 10.0 and 3.6 GPa, respectively, and transition pressure point of BaC2 agrees well with recent theoretical works. Based on the electronic analysis, the ionic Ca-C bond character becomes stronger with increasing pressure in both I4/mmm and R/line{3}m phases. In particular, there will occur a transition from insulator to metal with increasing pressure due to the reason that the calculated band gap gets narrower and finally closes at some high pressure.

Jiang, Li-Na

2013-12-01

216

Automated pressure regulator  

International Nuclear Information System (INIS)

A pressure regulator has been constructed that automatically nulls a sensitive differential pressure indicator of the type used in high-quality PVT experiments, thus permitting at least partial automation of such experiments. Distinguishing features are: high resolution, sufficient rigidity for operation in a pressure range up to 100 MPa, and a control logic that permits nulling of the pressure transducer, even if the initial state is very far from balance

217

A Balancing Act: A Quantitative Analysis of the Influence of Work/Life Balance and Work Atmosphere on Personal and Professional Success of Women Scientists  

Science.gov (United States)

Despite an increase in advanced degrees awarded to women in the geosciences, scientific leaders in academia remain dominantly male. Women are underrepresented in tenure-track positions in Earth science departments at research universities and are less likely to have more senior positions within their academic institutions. Our empirical study analyzes factors that influence personal and professional success for women scientists. Prior research has shown that women are subjected to unintended and unrecognized biases that can have an ultimate impact on their productivity, advancement, and success. We used an electronic survey to collect data from 662 early-career geoscientists who are members of the Earth Science Women's Network and/or the network's Earth Science Jobs list. We asked respondents to self-report their perceptions of work/life balance, professional atmosphere and other variables indicative and/or predictive of personal and professional success. In a previous analysis (Kogan & Laursen, 2011) we found that women consistently rated the professional atmosphere in their departments and their interactions with colleagues less favorably than men. Women indicated lower rates of collaboration with colleagues in their unit compared to their male peers. We also found work/life balance is of particular concern to early-career scientists, especially since tenure clock and the biological clock function on similar timetables. Women reported more caregiving responsibilities than men, further complicating the balance between work and personal life. We hypothesize that the work life balance and professional atmosphere influences productivity, advancement, and career/job satisfaction. We now investigate how work/life balance, atmosphere within the work unit, and mentoring influence productivity, job and career satisfaction, and career advancement. We introduce a structural equation model that seeks to explain how these relationships vary dependent upon gender, career level, caretaking responsibilities, and other variables. Our data indicate strong positive correlations between professional climate and job satisfaction, and between work/life balance and productivity. Our results suggest that the uneven pressures experienced by women influence their ability to achieve personal and professional success. However, our model implies that positive changes in women's work/life balance and professional atmosphere have the potential to help them become more successful both professionally and personally.

Archie, T.; Laursen, S. L.; Kogan, M.

2012-12-01

218

Bulk Earth carbon and its isotopic value  

Science.gov (United States)

The carbon isotope distribution in the Earth today is the net product of several primary processes, including planetary accretion, segregation of the core, the Moon-forming giant impact, magma oceans, crustal recycling, and biological processes. Therefore carbon isotope fractionation under mantle pressure and temperature conditions is one of the most important factors in deciphering the messages recorded in mantle samples and will assist towards the greater understanding the geodynamic carbon system. The largest and most powerful geochemical differentiation event during Earth's geologic history was core formation. The behaviour of 13C during this process is little constrained and needs to be investigated to understand the potential effects that it may have had on the carbon isotope composition of the silicate Earth. Isotopic fractionation of carbon at mantle pressure and temperatures in laboratory experiments and for natural terrestrial and extra-terrestrial samples between coexisting elemental carbon and carbides (reducing conditions) are higher than other systems previously investigated and can exceed 12 ‰ in the cores of celestial bodies and observed in Fe-meteorites (Deines and Wickman, 1975; Mikhail et al., 2010). First we review the mean values for carbon in ordinary chondrites and other solar system meteorites (from Mars, Vesta and the Moon) with a value of ?13C ? -20 +/- 4 ‰ (Grady et al 2004). Then we review the notion that the bulk Earth ?13C is around -5 ‰ similar to enstatite and carbonaceous chondrites and reflected in the majority of peridotitic mantle materials. Our modelling demonstrates that in order to understand the core/mantle carbon ratio we need to constrain the bulk Earth's initial ?13C value. We can constrain the relative proportion of carbon in the core/mantle by using simple isotopic mass balance and produce a range of carbon contents for the Earth then apply this to the maximum and minimums for the core using geophysical constraints. The mantle dominates the terrestrial carbon reservoir from an initial ?13C value of -5 ‰, but is dwarfed by the core with an initial ?13C value of -20 ‰. REFERENCES: S. Mikhail 2010 AGU U21A-001 abstract; Deines, P., Wickman, F.E., 1975. A contribution to the stable carbon isotope geochemistry of iron meteorites. Geochimica Et Cosmochimica Acta 39, 547-557. Grady, M. Verchovsky A, Wright, I. 2004 Magmatic carbon in Martian meteorites: attempts to constrain the carbon cycle on Mars. Int. J. Astrobiol. 2004;3:117-124.

Jones, A. P.; Mikhail, S.; Basugupta, S.

2012-12-01

219

Radiogenic heat production and the earth's heat balance. A source of arguments in geoscience; Radiogene Waermeproduktion und der Waermehaushalt der Erde. Ein Streitthema in der Geowissenschaft  

Energy Technology Data Exchange (ETDEWEB)

The terrestrial heat flow into interstellar space amounts to approx. 32 TW on the basis of an average heat flow density of 63 mW per sq.m. of earth surface. The loss flow derives part of the energy from the residual heat of the nascent phase of the earth (approx. 40%) and the other part from the natural disintegration of longlived radionuclides, i.e. radiogenic heat production (roughly 60%). This concept met with broad consensus in the geosciences until the 1980s. In 1993, Pollack et al. concluded from the evaluation of recent measured data that heat loss via the oceanic crust of the earth was clearly higher, which raises the loss flow to a total of 44 TW. This is contradicted by Hoffmeister and Criss, who conclude from a modified geochemical model that the total heat loss of 31 TW is fully compensated by radiogenic heat production. In 2001, C. Herndon introduced a new idea into the discussion. According to his thesis, planetary differentiation caused a nuclear georeactor to be created in the center of the earth, whose continuous thermal power of approx. 3 TW contributes to compensating heat losses. Physicists and geoscientists hope to be able to derive new findings on this thesis and on the distribution of radiogenic heat production in the interior of the earth from the planned geo-neutrino experiment in Homestake, USA. (orig.)

Kuczera, B.

2008-11-15

220

Balance and Stroke Risk  

Medline Plus

Full Text Available ... right-hand corner of the player. Balance and Stroke Risk HealthDay December 30, 2014 Related MedlinePlus Pages Balance Problems Stroke Transcript Can you balance on one leg for ...

 
 
 
 
221

Balanced Mind Foundation  

Science.gov (United States)

... Parent Network: Our Mission Get Started eNews Balanced Mind Updates Jul. 21, 2014 July eUpdate: DBSA Webinars ... Introducing the DBSA Young Adult Council Follow Balanced Mind Parent Network Updates: Balanced Mind Parent Network Updates ...

222

Google Earth  

Science.gov (United States)

Google Earth has gone underwater with this latest iteration of their popular Earth-roaming application. Along with traveling the usual roads provided by previous versions of Google Earth, visitors can now visit the bottom of the Mariana Trench, learn about ocean observations, and even discover new places to surf and dive. On the Google Earth homepage, visitors can take a guided tour of all these new features. This version is compatible with all operating systems.

2009-01-01

223

Earth Calendar  

Science.gov (United States)

This handout lists major events in Earth history with approximate ages (in millions of years before present). The calendar date is determined by setting midnight, January 1, to correspond with the formation of the Earth, and setting the following midnight, December 31, to correspond to the present. Thus, the entire history of the Earth is displayed as a single calendar year.

Barker, Jeffrey

224

Edible Earth  

Science.gov (United States)

In this activity, learners make a model of the solid Earth's layers that's good enough to eat! Learners use tasty foodstuffs to simulate Earth's inner core, outer core, mantle, and crust. The recipe includes ingredients for one edible Earth, but can be doubled or tripled to accommodate groups of learners. This activity requires adult supervision.

American Museum of Natural History

2011-08-20

225

Spooky sodium balance.  

Science.gov (United States)

Current teaching states that when sodium intake is increased from low to high levels, total-body sodium (TBNa) and water increase until daily sodium excretion again equals intake. When sodium intake is reduced, sodium excretion briefly exceeds intake until the excess TBNa and water are eliminated, at which point sodium excretion again equals intake. However, careful balance studies oftentimes conflict with this view and long-term studies suggest that TBNa fluctuates independent of intake or body weight. We recently performed the opposite experiment in that we fixed sodium intake for several weeks at three levels of sodium intake and collected all urine made. We found weekly (circaseptan) patterns in sodium excretion that were inversely related to aldosterone and directly to cortisol. TBNa was not dependent on sodium intake but instead exhibited far longer (? monthly) infradian rhythms independent of extracellular water, body weight, or blood pressure. The findings are consistent with our ideas on tissue sodium storage and its regulation that we developed on the basis of animal research. We are implementing (23)Na-magnetic resonance imaging (MRI) to pursue open questions on sodium balance in patients. Our findings could be relevant to therapeutic strategies for hypertension and target-organ damage. PMID:24107854

Titze, Jens; Dahlmann, Anke; Lerchl, Kathrin; Kopp, Christoph; Rakova, Natalia; Schröder, Agnes; Luft, Friedrich C

2014-04-01

226

Burnup of UO2-Gd2O3 nuclear fuel elements. Separation of gadolinium from rare earths by high pressure liquid chromatography (HPLC)  

International Nuclear Information System (INIS)

In the framework of a research project on burnable poisons, a technique to separate gadolinium from irradiated samples of (U-Gd)O2+x has been developed in order to determine the burnup of mixed oxides fuel elements. The separation of Gd from the other rare earths (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) has been carried out by HPLC after uranium extraction with TBP. The procedure can be applied as a step to determine the burnup of spent nuclear fuels

227

High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties  

Science.gov (United States)

Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB6, SrB6, BaB6 and the ternary hexaborides CaxSr1-xB6, CaxBa1-xB6, SrxBa1-xB6 (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB6 (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process.

Gürsoy, M.; Takeda, M.; Albert, B.

2015-01-01

228

A New Carbonate Chemistry in the Earth's Lower Mantle  

Science.gov (United States)

The global geochemical carbon cycle involves exchange between the Earth’s mantle and the surface. Carbon (C) is recycled into the mantle via subduction and released to the atmosphere via volcanic outgassing. Carbonates are the main C-bearing minerals that are transported deep in the Earth’s mantle via subduction of the oceanic lithosphere [1]. The way C is recycled and its contribution to the lower mantle reservoir is however largely unknown [ e.g 2, 3]. In this respect, it is important to assess if carbonates can be preserved in the deep mantle, or if decarbonatation, melting or reduction play a role in the deep carbon cycle. To clarify the fate of carbonates in the deep mantle, we carried out high-pressure and high-temperature experiments up to 105 GPa and 2850 K. Natural Fe-Mg carbonates or oxide mixtures of (Mg,Fe)O + CO2 were loaded into laser heated diamond anvil cells. In situ characterizations were done by X-ray Diffraction (XRD) using synchrotron radiation at the high-pressure beamline ID27 of the European Synchrotron Radiation Facility. A focused ion beam technique was then used to prepare the recovered samples for electron energy loss spectroscopy in a dedicated scanning transmission electron microscope (EELS-STEM) and scanning transmission X-ray microscopy (STXM). In situ XRD clearly shows the transformation of the initial carbonate phase into a new Mg-Fe high pressure carbonate phase at lower mantle conditions. We also provide direct evidence for recombination of CO2 with (Mg,Fe)O to form this new carbonate structure. In addition, subsequent EELS-STEM and STXM spectroscopies carried out on recovered samples yields C K-edge and stoechiometry characteristic to this new carbonate structure. This new high pressure phase concentrates a large amount of Fe(III), as a result of redox reactions within the siderite-rich carbonate. The oxidation of iron is balanced by partial reduction of carbon into CO groups and/or diamond. These reactions may provide an explanation for the coexistence of oxidized and reduced C species observed on natural samples [4, 5], but also a new diamond formation mechanism at lower mantle conditions. [1] Sleep, N. H., and K. Zahnle (2001) J. Geophys. Res.-Planets 106(E1), 1373-1399. [2] Javoy, M. (1997) Geophys. Res. Lett. 24(2), 177-180. [3] Lecuyer et al. (2000) Earth Planet. Sci. Lett. 181(1-2), 33-40. [4] Brenker et al. (2007) Earth Planet. Sci. Lett. 260(1-2), 1-9. [5] Stachel et al. (2000) Contrib. Mineral. Petrol. 140(1), 16-27.

Boulard, E.; Gloter, A.; Corgne, A.; Antonangeli, D.; Auzende, A.; Perrillat, J.; Guyot, F. J.; Fiquet, G.

2010-12-01

229

THE COSMIC-RAY INTENSITY NEAR THE ARCHEAN EARTH  

Energy Technology Data Exchange (ETDEWEB)

We employ three-dimensional state-of-the-art magnetohydrodynamic models of the early solar wind and heliosphere and a two-dimensional model for cosmic-ray transport to investigate the cosmic-ray spectrum and flux near the Archean Earth. We assess how sensitive the cosmic-ray spectrum is to changes in the sunspot placement and magnetic field strength, the large-scale dipole magnetic field strength, the wind ram pressure, and the Sun's rotation period. Overall, our results confirm earlier work that suggested the Archean Earth would have experienced a greatly reduced cosmic-ray flux than is the case today. The cosmic-ray reduction for the early Sun is mainly due to the shorter solar rotation period and tighter winding of the Parker spiral, and to the different surface distribution of the more active solar magnetic field. These effects lead to a global reduction of the cosmic-ray flux at 1 AU by up to two orders of magnitude or more. Variations in the sunspot magnetic field have more effect on the flux than variations in the dipole field component. The wind ram pressure affects the cosmic-ray flux through its influence on the size of the heliosphere via the pressure balance with the ambient interstellar medium. Variations in the interstellar medium pressure experienced by the solar system in orbit through the Galaxy could lead to order of magnitude changes in the cosmic-ray flux at Earth on timescales of a few million years.

Cohen, O.; Drake, J. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kota, J. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092 (United States)

2012-11-20

230

Titan's Greenhouse Effect And Climate: Lessons From The Earth's Cooler Cousin  

Science.gov (United States)

We argue that continuing scientific study of Earth's `distant cousin’ Titan can provide a greater understanding and insight into the energy balance of our own planet's atmosphere. Titan's Earth-like properties have been recognized for some time, from the discovery of its atmosphere in 1907, through the Voyager 1 encounter in 1980 that showed Titan's atmosphere is mostly nitrogen gas with a surface pressure within a factor of two of terrestrial. Calculation shows that Titan's atmosphere causes `greenhouse’ warming of the surface, an effect similar to that seen on the Earth, Mars, and Venus. In the 1990s, direct imaging from the Earth by adaptive optics revealed that Titan's ubiquitous haze layer is slowly changing in apparent response to the seasons that occur due to the Saturn system's obliquity. The NASA Cassini mission that arrived in Saturnian orbit in 2004, and the ESA Huygens Titan probe of 2005, have returned a flood of new data regarding this intriguing world. For the first time, we are building a detailed picture of weather in the lower atmosphere, where condensable methane takes on the role played by water in the Earth's atmosphere, leading to methane rainfall, rivers and lakes. We examine parallels between the atmospheres of Earth and of Titan, including the possibilities for dramatic climate change. Extending the duration of the Cassini spacecraft mission during the next decade will provide part of the needed picture, but in addition we urge planning for a future new mission focused on Titan's climate, and other measures.

Nixon, Conor A.; Titan Climate White Paper Proposal Team

2009-12-01

231

Earth Force  

Science.gov (United States)

"Earth Force engages young people as active citizens who improve the environment and their communities now and in the future." Educators can learn about Earth Force's three programs: Community Action and Problem solving (CAPS), the Global Rivers Environmental Education Network (GREEN), and Earth Force After School. Users can discover students' many accomplishments such as creating reusable fabric grocery bags, recycling cell phones and ink cartridges to earn money, and cleaning up litter. The Tools for Teachers section offers evaluation results, a quality rubric, and a description of the six-step Earth Force community action and problem-solving process.

232

Using Multi-threading for the Automatic Load Balancing of 2D Adaptive Finite Element Meshes  

Science.gov (United States)

In this paper, we present a multi-threaded approach for the automatic load balancing of adaptive finite element (FE) meshes The platform of our choice is the EARTH multi-threaded system which offers sufficient capabilities to tackle this problem. We implement the adaption phase of FE applications oil triangular meshes and exploit the EARTH token mechanism to automatically balance the resulting irregular and highly nonuniform workload. We discuss the results of our experiments oil EARTH-SP2, on implementation of EARTH on the IBM SP2 with different load balancing strategies that are built into the runtime system.

Heber, Gerd; Biswas, Rupak; Thulasiraman, Parimala; Gao, Guang R.; Saini, Subhash (Technical Monitor)

1998-01-01

233

Using Multithreading for the Automatic Load Balancing of 2D Adaptive Finite Element Meshes  

Science.gov (United States)

In this paper, we present a multi-threaded approach for the automatic load balancing of adaptive finite element (FE) meshes. The platform of our choice is the EARTH multi-threaded system which offers sufficient capabilities to tackle this problem. We implement the question phase of FE applications on triangular meshes, and exploit the EARTH token mechanism to automatically balance the resulting irregular and highly nonuniform workload. We discuss the results of our experiments on EARTH-SP2, an implementation of EARTH on the IBM SP2, with different load balancing strategies that are built into the runtime system.

Heber, Gerd; Biswas, Rupak; Thulasiraman, Parimala; Gao, Guang R.; Bailey, David H. (Technical Monitor)

1998-01-01

234

Ce{sub 2}B{sub 8}O{sub 15}. High-pressure synthesis and crystal structure determination of a rare-earth polyborate exhibiting a new 'Fundamental Building Block'  

Energy Technology Data Exchange (ETDEWEB)

The new cerium polyborate Ce{sub 2}B{sub 8}O{sub 15} was synthesized under high-pressure/high-temperature conditions of 6 GPa and 1050 C in a Walker-type multianvil apparatus. The single-crystal structure determination revealed that the new compound crystallizes in the space group P2/c with the lattice parameters a = 916.6(2), b = 421.0(1), c = 1248.9(3) pm, {beta} = 116.7(1) , V = 0.4303(2) nm{sup 3}, R1 = 0.0356, and wR2 = 0.0504. The crystal structure of Ce{sub 2}B{sub 8}O{sub 15} exhibits a new fundamental building block (FBB) in borate chemistry that consists of four BO{sub 4} tetrahedra and can be written as 4{open_square}: [{Phi}] left angle 3{open_square} right angle vertical stroke {open_square} vertical stroke. These FBB are interconnected via common corners, forming a complex threedimensional network that contains the Ce{sup 3+} cations. Ce{sub 2}B{sub 8}O{sub 15} represents the most boron rich rare-earth borate synthesized under high-pressure/high-temperature conditions so far. We report about the synthetic conditions, structural details, thermal behaviour, and the IR/Raman spectra of Ce{sub 2}B{sub 8}O{sub 15}. (orig.)

Glaetzle, Matthias; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

2013-10-01

235

Earth\\'s Mass Variability  

CERN Document Server

The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

Mawad, Ramy

2014-01-01

236

Balance control impairment in obese individuals is caused by larger balance motor commands variability.  

Science.gov (United States)

It is acknowledged that various factors impaired balance control. Among them, heavy body weight is associated with poor balance control because the location of the center of mass is further away from the ankle joint. Thus, a larger active ankle torque is required to counter the greater gravitational torque. Because balance motor commands have signal-dependent noise whose standard deviation increases with the absolute value of the neural control signal, it was hypothesized that faster center of pressure speed observed in obese individuals would be related to larger balance motor commands variability. A feedback-control model and parametric system identification technique was used to estimate the variability in the balance motor commands and neural controller parameters based on previously published experimental data. Results of the neuromechanical model confirmed that the balance motor commands of obese individuals are more variable than that of lean individuals. PMID:25455209

Simoneau, Martin; Teasdale, Normand

2015-01-01

237

Melting in super-earths.  

Science.gov (United States)

We examine the possible extent of melting in rock-iron super-earths, focusing on those in the habitable zone. We consider the energetics of accretion and core formation, the timescale of cooling and its dependence on viscosity and partial melting, thermal regulation via the temperature dependence of viscosity, and the melting curves of rock and iron components at the ultra-high pressures characteristic of super-earths. We find that the efficiency of kinetic energy deposition during accretion increases with planetary mass; considering the likely role of giant impacts and core formation, we find that super-earths probably complete their accretionary phase in an entirely molten state. Considerations of thermal regulation lead us to propose model temperature profiles of super-earths that are controlled by silicate melting. We estimate melting curves of iron and rock components up to the extreme pressures characteristic of super-earth interiors based on existing experimental and ab initio results and scaling laws. We construct super-earth thermal models by solving the equations of mass conservation and hydrostatic equilibrium, together with equations of state of rock and iron components. We set the potential temperature at the core-mantle boundary and at the surface to the local silicate melting temperature. We find that ancient (?4?Gyr) super-earths may be partially molten at the top and bottom of their mantles, and that mantle convection is sufficiently vigorous to sustain dynamo action over the whole range of super-earth masses. PMID:24664915

Stixrude, Lars

2014-04-28

238

Re-entry dynamics of high area-to-mass ratio objects in eccentric Earth orbits considering drag and solar radiation pressure  

International Nuclear Information System (INIS)

The discovery of a new population of objects with high area-to-mass ratios (HAMR) in orbits near the geostationary ring has motivated recent research seeking to understand the behaviour of those debris under the influence of certain types of disturbances, such as solar radiation pressure and atmospheric drag. Based on a series of selection criteria, it was made from the NORAD catalogue a list of potential candidates for study. As we developed an orbital propagator that takes into account the major disturbances, it was possible to study the behaviour and variation of orbital parameters during decay of the HAMR objects. The results obtained for two cases studied exhibit the dynamic behaviour of all orbital parameters and show good agreement with the observed decay times

239

Performance of balanced bellows safety relief valves  

International Nuclear Information System (INIS)

By the nature of its design, the set point and lift of a conventional spring loaded safety relief valve are sensitive to back pressure. One way to reduce the adverse effects of the back pressure on the safety relief valve function is to install a balanced bellows in a safety relief valve. The metallic bellows has a rather wide range of manufacturing tolerance which makes the design of the bellows safety relief valve very complicated. The state-of-the-art balanced bellows safety relief valve can only substantially minimize, but cannot totally eliminate the back pressure effects on its set point and relieving capacity. Set point change is a linear function of the back pressure to the set pressure ratio. Depending on the valve design, the set point correction factor can be either greater or smaller than unity. There exists an allowable back pressure and critical back pressure for each safety relief valve. When total back pressure exceeds the Ra, the relieving capacity will be reduced mainly resulting from the valve lift being reduced by the back pressure and the capacity reduction factor should be applied in valve sizing. Once the Rc is exceeded, the safety relief valve becomes unstable and loses its over pressure protection capability. The capacity reduction factor is a function of system overpressure, but their relationship is non-linear in nature. (orig.)

240

Dizziness and Balance  

Science.gov (United States)

... as acoustic neuroma) Head injury Migraine What is vertigo? Vertigo is a type of dizziness in which there ... seem worse. Nausea and vomiting may accompany the vertigo at times. Balance testing Balance system assessment is ...

 
 
 
 
241

Random walk and balancing  

CERN Document Server

Presents a minireview of topics concerned with balancing in quiet (bipedal) standing, and balancing of a stick. In the focus is the apparent stochastic nature of the swaying of the human inverted pendulum.

Borg, F G

2004-01-01

242

Human Balance System  

Science.gov (United States)

... support. 1 A properly functioning balance system allows humans to see clearly while moving, identify orientation with ... Dr. Daniel Merfeld, Massachusettes Eye & Ear Infirmary The human balance system involves a complex set of sensorimotor- ...

243

Monkey Math Balance  

Science.gov (United States)

In this interactive Flash game, players must balance the scale by having the same sum on both sides. Numbers are presented on coconuts and students must figure how to group them to equalize the balance.

Project, Vaisaga

2009-07-01

244

Plant adaptation to low atmospheric pressures: potential molecular responses  

Science.gov (United States)

There is an increasing realization that it may be impossible to attain Earth normal atmospheric pressures in orbital, lunar, or Martian greenhouses, simply because the construction materials do not exist to meet the extraordinary constraints imposed by balancing high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow plants at reduced atmospheric pressure. Yet current understanding of plant growth at low pressures is limited to just a few experiments and relatively rudimentary assessments of plant vigor and growth. The tools now exist, however, to make rapid progress toward understanding the fundamental nature of plant responses and adaptations to low pressures, and to develop strategies for mitigating detrimental effects by engineering the growth conditions or by engineering the plants themselves. The genomes of rice and the model plant Arabidopsis thaliana have recently been sequenced in their entirety, and public sector and commercial DNA chips are becoming available such that thousands of genes can be assayed at once. A fundamental understanding of plant responses and adaptation to low pressures can now be approached and translated into procedures and engineering considerations to enhance plant growth at low atmospheric pressures. In anticipation of such studies, we present here the background arguments supporting these contentions, as well as informed speculation about the kinds of molecular physiological responses that might be expected of plants in low-pressure environments.

Ferl, Robert J.; Schuerger, Andrew C.; Paul, Anna-Lisa; Gurley, William B.; Corey, Kenneth; Bucklin, Ray

2002-01-01

245

Isotope composition and volume of Earth´s early oceans  

DEFF Research Database (Denmark)

Oxygen and hydrogen isotope compositions of Earth´s seawater are controlled by volatile fluxes among mantle, lithospheric (oceanic and continental crust), and atmospheric reservoirs. Throughout geologic time the oxygen mass budget was likely conserved within these Earth system reservoirs, but hydrogen´s was not, as it can escape to space. Isotopic properties of serpentine from the approximately 3.8 Ga Isua Supracrustal Belt in West Greenland are used to characterize hydrogen and oxygen isotope compositions of ancient seawater. Archaean oceans were depleted in deuterium [expressed as δD relative to Vienna standard mean ocean water (VSMOW)] by at most 25± 5‰, but oxygen isotope ratios were comparable to modern oceans. Mass balance of the global hydrogen budget constrains the contribution of continental growth and planetary hydrogen loss to the secular evolution of hydrogen isotope ratios in Earth´s oceans. Our calculations predict that the oceans of early Earth were up to 26% more voluminous, and atmospheric CH4 and CO2 concentrations determined from limits on hydrogen escape to space are consistent with clement conditions on Archaean Earth.

Pope, Emily Catherine; Bird, Dennis K.

2012-01-01

246

Balance and Stroke Risk  

Medline Plus

Full Text Available ... player. Balance and Stroke Risk HealthDay December 30, 2014 Related MedlinePlus Pages Balance Problems Stroke Transcript Can ... to look for small blood vessel disease. The results? People who were unable to balance on one ...

247

Can You Balance?  

Science.gov (United States)

This interactive Flash tool allows primary students to explore the concepts of equality and inequality with a balance. Learners receive cubes on both sides of a balance and must select from the given choices to determine the correct number of cubes to equalize the balance.

2009-01-01

248

Rare earths  

International Nuclear Information System (INIS)

The conference was held from September 12 to 13, 1984 in Jetrichovice, Czechoslovakia. The participants heard 16 papers of which 4 were inputted in INIS. These papers dealt with industrial separation processes of rare earths, the use of chemical methods of separation from the concentrate of apatite and bastnesite, the effect of the relative permittivity of solvents in the elution of rare earth elements from a cation exchanger, and the determination of the content of different rare earth elements using X-ray fluorescence analysis and atomic absorption spectroscopy. (E.S.)

249

JAMA Patient Page: Pressure Ulcers  

Science.gov (United States)

... other contributing illnesses, and implementation of a healthy diet. Relieving or reducing the pressure on the area is essential. Once an ulcer appears, additional treatment options can include: • Local ulcer care, including maintaining proper moisture balance and use of anti- ...

250

DYMAC digital electronic balance  

International Nuclear Information System (INIS)

The Dynamic Materials Accountability (DYMAC) System at LASL integrates nondestructive assay (NDA) instruments with interactive data-processing equipment to provide near-real-time accountability of the nuclear material in the LASL Plutonium Processing Facility. The most widely used NDA instrument in the system is the DYMAC digital electronic balance. The DYMAC balance is a commercial instrument that has been modified at LASL for weighing material in gloveboxes and for transmitting the weight data directly to a central computer. This manual describes the balance components, details the LASL modifications, reviews a DYMAC measurement control program that monitors balance performance, and provides instructions for balance operation and maintenance

251

Earth Day  

Science.gov (United States)

The State University of New York at Buffalo presents this History of Earth Day website. The goal of the site is that teachers and students can better understand the development and purpose of Earth Day. In addition to the history, SUNY-Buffalo has compiled a series of websites complete with projects associated with Earth Day, appropriate for children, high school students, and college undergrads. Furthermore, the legal aspect of Earth Day - environmental legislation, EPA standards, and Global Climate Change legislation - are also discussed on the site. A list of further sites is also provided if users want more information on this national effort to help solve environmental issues such as pollution, overpopulation, and global warming. Teachers will find this website both informative and helpful in developing appropriate teaching curricula connected to this holiday, while students can have fun learning and creating projects of their own that contribute to preserving the environment.

2007-04-19

252

Earth Systems  

Science.gov (United States)

This self-contained module on Earth systems includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

Houghton Mifflin Science

253

Earth's Surface  

Science.gov (United States)

This self-contained module on Earth's crust includes a range of fun activities that students can perform in the classroom and at home with family members. They impart important concepts such as observation, identification, measurement, and differentiation.

Houghton Mifflin Science

254

Medical Devices Assess, Treat Balance Disorders  

Science.gov (United States)

You may have heard the phrase as difficult as walking and chewing gum as a joking way of referring to something that is not difficult at all. Just walking, however, is not all that simple physiologically speaking. Even standing upright is an undertaking requiring the complex cooperation of multiple motor and sensory systems including vision, the inner ear, somatosensation (sensation from the skin), and proprioception (the sense of the body s parts in relation to each other). The compromised performance of any of these elements can lead to a balance disorder, which in some form affects nearly half of Americans at least once in their lifetimes, from the elderly, to those with neurological or vestibular (inner ear) dysfunction, to athletes with musculoskeletal injuries, to astronauts returning from space. Readjusting to Earth s gravity has a significant impact on an astronaut s ability to balance, a result of the brain switching to a different "model" for interpreting sensory input in normal gravity versus weightlessness. While acclimating, astronauts can experience headaches, motion sickness, and problems with perception. To help ease the transition and study the effects of weightlessness on the body, NASA has conducted many investigations into post-flight balance control, realizing this research can help treat patients with balance disorders on Earth as well. In the 1960s, the NASA-sponsored Man Vehicle Laboratory at the Massachusetts Institute of Technology (MIT) studied the effects of prolonged space flight on astronauts. The lab s work intrigued MIT doctoral candidate Lewis Nashner, who began conducting NASA-funded research on human movement and balance under the supervision of Dr. Larry Young in the MIT Department of Aeronautics and Astronautics. In 1982, Nashner s work resulted in a noninvasive clinical technique for assessing the cooperative systems that allow the body to balance, commonly referred to as computerized dynamic posturography (CDP). CDP employs a series of dynamic protocols to isolate and assess balance function deficiencies. The technology was based on Nashner s novel, engineering-inspired concept of balance as an adaptable collaboration between multiple sensory and motor systems. CDP proved useful not only for examining astronauts, but for anyone suffering from balance problems. Today, CDP is the standard medical tool for objectively evaluating balance control.

2009-01-01

255

Future Satellite Gravimetry and Earth Dynamics  

CERN Document Server

Currently, a first generation of dedicated satellite missions for the precise mapping of the Earth’s gravity field is in orbit (CHAMP, GRACE, and soon GOCE). The gravity data from these satellite missions provide us with very new information on the dynamics of planet Earth. In particular, on the mass distribution in the Earth’s interior, the entire water cycle (ocean circulation, ice mass balance, continental water masses, and atmosphere), and on changes in the mass distribution. The results are fascinating, but still rough with respect to spatial and temporal resolution. Technical progress in satellite-to-satellite tracking and in gravity gradiometry will allow more detailed results in the future. In this special issue, Earth scientists develop visions of future applications based on follow-on high-precision satellite gravimetry missions.

Flury, Jakob

2005-01-01

256

Low-Hysteresis Flow-Through Wind-Tunnel Balance  

Science.gov (United States)

Improved flow-through wind-tunnel balance includes features minimizing both spurious force readings caused by internal pressurized flow and mechanical hysteresis. Symmetrical forces caused by internal flow cancelled.

Kunz, N.; Luna, P. M.; Roberts, A. C.; Smith, R. C.; Horne, W. L.; Smith, K. M.

1992-01-01

257

Balance in Random Trees  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We prove that a random labeled (unlabeled) tree is balanced. We also prove that random labeled and unlabeled trees are strongly k-balanced for any k ≥ 3. Definition: Color the vertices of graph G with two colors. Color an edge with the color of its endpoints if they are colored with the same color. Edges with different colored endpoints are left uncolored. G is said to be balanced if neither the number of vertices nor and the num...

Azer Akhmedov; Warren Shreve

2014-01-01

258

Technique for Enhanced Rare Earth Separation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A process is demonstrated for the efficient separation of rare earth elements, using a combination of selective reduction and vacuum distillation of halides. The large differences in the redox chemistry of the rare earth elements and in the vapor pressures of rare earth di- and trihalides are exploited for separation. Experimental proof of concept is provided for the binary systems praseodymium-neodymium and neodymium-samarium. This process enhances the separation factor for the isolation of ...

Uda, Tetsuya; Jacob, Thomas K.; Hirasawa, Masahiro

2000-01-01

259

Digital Earth - A sustainable Earth  

Science.gov (United States)

All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

Mahavir

2014-02-01

260

Earth's magnetosphere  

International Nuclear Information System (INIS)

The following aspects of the Earth's magnetosphere were discussed: general structure, magnetic field merging and magnetospheric convection, time-varying convection and magnetospheric substorms, magnetic storms, and comparative magnetospheres. Solar flares and the magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, and Uranus were also described

 
 
 
 
261

Balanced fractional opial inequalities  

Energy Technology Data Exchange (ETDEWEB)

Here we present L{sub p}, p>1, fractional Opial type inequalities subject to high order boundary conditions. They involve the right and left Caputo, Riemann-Liouville fractional derivatives. These derivatives are blended together into the balanced Caputo, Riemann-Liouville, respectively, fractional derivative. This balanced fractional derivative is introduced here for the first time. We give applications to a special case.

Anastassiou, George A. [Department of Mathematical Sciences, University of Memphis, Memphis, TN 38152 (United States)], E-mail: ganastss@gmail.com

2009-11-15

262

Balanced fractional opial inequalities  

International Nuclear Information System (INIS)

Here we present Lp, p>1, fractional Opial type inequalities subject to high order boundary conditions. They involve the right and left Caputo, Riemann-Liouville fractional derivatives. These derivatives are blended together into the balanced Caputo, Riemann-Liouville, respectively, fractional derivative. This balanced fractional derivative is introduced here for the first time. We give applications to a special case.

263

Leadership: A Balancing Act  

Science.gov (United States)

Maintaining balance in leadership can be difficult because balance is affected by the personality, strengths, and attitudes of the leader as well as the complicated environment within and outside the community college itself. This article explores what being a leader at the community college means, what the threats are to effective leadership, and…

Hines, Thomas E.

2011-01-01

264

Balance and Stroke Risk  

Medline Plus

Full Text Available ... hand corner of the player. Balance and Stroke Risk HealthDay December 30, 2014 Related MedlinePlus Pages Balance ... answer is yes, you may be at lower risk for brain disease and stroke than people who ...

265

Judicial Checks and Balances  

Science.gov (United States)

In the Anglo-American constitutional tradition, judicial checks and balances are often seen as crucial guarantees of freedom. Hayek distinguishes two ways in which the judiciary provides such checks and balances: judicial independence and constitutional review. We create a new database of constitutional rules in 71 countries that reflect these…

La Porta, Rafael; Lopez-de-Silanes, Florencio; Pop-Eleches, Cristian; Shleifer, Andrei

2004-01-01

266

Mass balance myths  

International Nuclear Information System (INIS)

In the event of an oil spill at sea, remediation technologies rely on oil spill monitoring and mass balance calculations. The types of oil spills that require knowledge of mass-balance include weathering studies, dispersant-effectiveness testing, measurement of response effectiveness and damage assessment. Non-destructive and non-interfering measuring methods are needed to find components of the mass balance equation such as temporal and spatial distribution of the oil thickness, and the temporal and spatial distribution of oil concentration in the sub-surface plume. The main challenge is the variation in the size scale of laboratory and open ocean measurements. Most large scale oil-spill experiments do not have scientific credibility because there are few situations in which all the oil in the system is accounted for. While some components are accurately accounted for, others ignore mass balance, or the range of measurements is not sufficient to allow for computation of mass balance. 48 refs

267

Engine balancing system  

Energy Technology Data Exchange (ETDEWEB)

This patent describes a single-cylinder engine comprising a crank shaft, a crank web connected to the crank shaft, a connecting rod connected to the crank web through a crank pin, a cylinder, and a piston connected to the connecting rod to move in reciprocatory movement within the cylinder. An engine balancing system is described comprising: a counter balancer supported by the crank web; and a single primary balancer rotatably supported by a shaft extending parallel to the crank shaft. The single primary balancer is driven to rotate at a velocity equal to that of the counterbalancer in a direction opposite to a direction of rotation of the counterbalancer; wherein a center line of the cylinder of the engine deviates from a center of rotation of the crank shaft toward the single primary balancer.

Fujikawa, T.; Hirata, M.; Tamba, S.; Miguchi, A.

1986-12-16

268

Rotating Balances Used for Fluid Pump Testing  

Science.gov (United States)

Marshall Space Flight Center has developed and demonstrated two direct read force and moment balances for sensing and resolving the hydrodynamic loads on rotating fluid machinery. These rotating balances consist of a series of stainless steel flexures instrumented with semiconductor type, unidirectional strain gauges arranged into six bridges, then sealed and waterproofed, for use fully submerged in degassed water at rotational speeds up to six thousand revolutions per minute. The balances are used to measure the forces and moments due to the onset and presence of cavitation or other hydrodynamic phenomena on subscale replicas of rocket engine turbomachinery, principally axial pumps (inducers) designed specifically to operate in a cavitating environment. The balances are inserted into the drive assembly with power to and signal from the sensors routed through the drive shaft and out through an air-cooled twenty-channel slip ring. High frequency data - balance forces and moments as well as extensive, flush-mounted pressures around the rotating component periphery - are acquired via a high-speed analog to digital data acquisition system while the test rig conditions are varied continuously. The data acquisition and correction process is described, including the in-situ verifications that are performed to quantify and correct for known system effects such as mechanical imbalance, "added mass," buoyancy, mechanical resonance, and electrical bias. Examples of four types of cavitation oscillations for two typical inducers are described in the laboratory (pressure) and rotating (force) frames: 1) attached, symmetric cavitation, 2) rotating cavitation, 3) attached, asymmetric cavitation, and 4) cavitation surge. Rotating and asymmetric cavitation generate a corresponding unbalanced radial force on the rotating assembly while cavitation surge generates an axial force. Attached, symmetric cavitation induces no measurable force. The frequency of the forces can be determined a priori from the pressure environment while the magnitude of the hydrodynamic force is proportional to the pressure unsteadiness.

Skelley, Stephen; Mulder, Andrew

2014-01-01

269

Near-earth Thin Current Sheets and Birkeland Currents during Substorm Growth Phase  

International Nuclear Information System (INIS)

Two important phenomena observed during the magnetospheric substorm growth phase are modeled: the formation of a near-Earth (|X| ? 9 RE) thin cross-tail current sheet, as well as the equatorward shift of the ionospheric Birkeland currents. Our study is performed by solving the 3-D force-balance equation with realistic boundary conditions and pressure distributions. The results show a cross-tail current sheet with large current (J? ? 10 nA/m2) and very high plasma ? (? ? 40) between 7 and 10 RE. The obtained region-1 and region-2 Birkeland currents, formed on closed field lines due to pressure gradients, move equatorward and become more intense (Jparallelmax ? 3 (micro)A/m2) compared to quiet times. Both results are in agreement with substorm growth phase observations. Our results also predict that the cross-tail current sheet maps into the ionosphere in the transition region between the region-1 and region-2 currents

270

Development of the NTF-117S Semi-Span Balance  

Science.gov (United States)

A new high-capacity semi-span force and moment balance has recently been developed for use at the National Transonic Facility at the NASA Langley Research Center. This new semi-span balance provides the NTF a new measurement capability that will support testing of semi-span test models at transonic high-lift testing regimes. Future testing utilizing this new balance capability will include active circulation control and propulsion simulation testing of semi-span transonic wing models. The NTF has recently implemented a new highpressure air delivery station that will provide both high and low mass flow pressure lines that are routed out to the semi-span models via a set high/low pressure bellows that are indirectly linked to the metric end of the NTF-117S balance. A new check-load stand is currently being developed to provide the NTF with an in-house capability that will allow for performing check-loads on the NTF-117S balance in order to determine the pressure tare affects on the overall performance of the balance. An experimental design is being developed that will allow for experimentally assessing the static pressure tare affects on the balance performance.

Lynn, Keith C.

2010-01-01

271

Earth Institute  

Science.gov (United States)

The mission of the Earth Institute at Columbia University is to help the world achieve sustainability by expanding understanding of the Earth as one integrated system. Through research, education, and the practical application of research to real-world challenges, the Institute addresses nine interconnected global issues: climate and society, water, energy, poverty, ecosystems, public health, food and nutrition, and hazards and urbanization. The Institute's site offers a collection of videotaped events, including the biannual "State of the Planet" conferences, 2002-08, a Distinguished Lecture series, and the Sustainable Development seminar series, as well as e-seminars and e-briefings, information about funding opportunities, and information about educational opportunities at Columbia.

272

Earth's Water  

Science.gov (United States)

The total amount of water on Earth, the places in which it is found and the percentages of fresh vs. salt are examined in this lesson. A short demonstration allows students to visualize the percentage differences and a coloring exercise illustrates locations. This lesson uses the 5E instructional model. All background information, student worksheets and images/photographs/data are included in these downloadable sections: Teacher's Guide, Student Capture Sheet and PowerPoint Presentation.

273

Balance in Random Trees  

Directory of Open Access Journals (Sweden)

Full Text Available We prove that a random labeled (unlabeled tree is balanced. We also prove that random labeled and unlabeled trees are strongly k-balanced for any k ≥ 3. Definition: Color the vertices of graph G with two colors. Color an edge with the color of its endpoints if they are colored with the same color. Edges with different colored endpoints are left uncolored. G is said to be balanced if neither the number of vertices nor and the number of edges of the two different colors differs by more than one.

Azer Akhmedov

2014-09-01

274

BIOCHEMISTRY: Balancing Cellular Energy  

Science.gov (United States)

Access to the article is free, however registration and sign-in are required. The structure of the core of an enzyme complex that senses and responds to changes in the cell's energy balance has been solved. Adenosine monophosphate-activated protein kinase (AMPK) complex regulates cellular energy balance. On page 1726 of this issue, Townley and Shapiro (2) describe crystal structures for the core of the AMPK complex from fission yeast. The study provides insights into binding of AMP and adenosine triphosphate (ATP), which may be very helpful in the design of new drugs that might treat disorders of energy balance (i.e. obesity and type-2 diabetes).

D. Grahame Hardie (University of Dundee;Division of Molecular Physiology)

2007-03-23

275

Social Balance Explanation  

Science.gov (United States)

A triad of attitudinal relationships is considered balanced if all three relationships are positive, or if one is positive and two are negative. Balance theory has been extended to apply to larger interpersonal groups (Situngkir & Khanafiah, 2004), perceptions of groups such as the US Supreme Court (Pilialoha & Brewer, 2006), matchmaking (Chapdelaine, Kenny, & LaFontana, 1994), the connection between voters and their political parties (Ray, 1999), bargaining (Kette, 1986), and developing a comprehensive theory of self-esteem, self-concept, implicit attitudes and stereotyping (Greenwald, Banaji, Rudman, Farnham, Nosek, & Mellot, 2002). This page describes a study that can be used to illustrate balance theory.

276

Balance of power  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper argues that the efficiency distribution of players in a game determines how aggressively these players interact.We formalize the idea of balance of power: players fight very inefficient players but play softly versus equally (or more) efficient players.This theory of conduct predicts that entry by new firms leads to a less aggressive outcome if it creates a balance of power. A balance of power is created if more players get technologies that are close to the most efficient technolo...

Lucas, James Raymond

2004-01-01

277

Getting the Balance  

Science.gov (United States)

This activity promotes algebraic thinking of equivalency as well as giving children practice in addition and subtraction. Since there are many different solutions for the values of the unknowns, learners can focus on the idea of working systematically. Students see two weights on one side of an interactive balance, and are asked to find how many different ways they can hang three weights on the other side for it to be balanced. An easier problem, "Number Balance", (cataloged separately) is linked on the problem page. The Teachers' Notes page offers rationale, suggestions for implementation, discussion questions, ideas for extension and support.

2007-08-01

278

Impact Earth  

Science.gov (United States)

This 24 minute planetarium show teaches about meteors, meteorites, asteroids, and comets. The show was created for fulldome theaters, but is also available on DVD to be shown in flat version for TVs and computer monitors, and can be freely viewed online. It shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall, and describes ways that asteroid hunters seek new objects in the solar system, and how ground penetrating radar is used to find meteorites that have survived to the Earth's surface. Narrated by astronaut Tom Jones, it also discusses ways that humans might try to deflect an asteroid or comet that is on a collision course with Earth. The show was created for informal science venues (digital planetariums); it is also useful as supplemental material for middle school science. Impact Earth is available for free if presented directly from the Space Update site (widescreen or fisheye views linked from YouTube). Otherwise, a DVD of the show can be purchased for $10.

279

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... people are discussing a problem common to many older adults -- a problem with balance. Balance problems can have a serious impact on an older person's life. In fact, balance problems are one ...

280

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... with each other -- kind of organized by the brain -- to help us maintain our balance, or, another ... balance nerve then sends the stimulation to the brain centers for balance. Another leg of the stool ...

 
 
 
 
281

Structure, force balance, and evolution of incompressible cross-tail current sheet thinning  

Science.gov (United States)

THEMIS five-point observations on April 8, 2009 were used to study thinning of the current sheet in the near-Earth tail that led to the onset of a small substorm. Taking advantage of a fortuitous alignment of the five spacecraft near 2300 LT and 11 RE and within 1.5 RE of the current sheet center, latitudinal gradients are analyzed. A significant latitudinal pressure gradient is present indicating the necessity of a (J × B)z force to maintain the pre-onset equilibrium state. During thinning the total pressure remained approximately constant at all spacecraft rather than increasing. Within the plasma sheet, magnetic field strength increased while plasma pressure decreased due to decreasing temperature. We present a comprehensive explanation for the relationship between the thinning, the stretched structure, and development of intense current density. Our analysis of this event suggests that (1) the thinning in this event is an MHD force-balanced self-evolving process and is not a forced process due to an increased lobe field; (2) the thinning changes flux tube structure in length and curvature but not significantly in volume; (3) the thinning evolves with a change of the radial plasma pressure profile in the near-Earth tail, which is associated with a locally intensified current sheet. The conclusion is that the increased lobe field strength is not the necessary and the primary cause for cross tail current sheet thinning but rather thinning can occur within the plasma sheet as a result of unknown internal processes.

Saito, M. H.; Fairfield, D.; Le, G.; Hau, L.-N.; Angelopoulos, V.; McFadden, J. P.; Auster, U.; Bonnell, J. W.; Larson, D.

2011-10-01

282

Susceptibility of the early Earth to irreversible glaciation caused by carbon dioxide clouds.  

Science.gov (United States)

Simple energy-balance climate models of the Budyko/Sellers type predict that a small (2-5%) decrease in solar output could result in runaway glaciation on the Earth. But solar fluxes 25-30% lower early in the Earth's history apparently did not lead to this result. One currently favoured explanation is that high partial pressures of carbon dioxide, caused by higher volcanic outgassing rates and/or slower rates of silicate weathering, created a large enough greenhouse effect to keep the planet warm. This does not resolve the problem of climate stability, however, because as we argue here, the oceans can freeze much more quickly than CO2 can accumulate in the atmosphere. Had such a transient global glaciation occurred in the distant past when solar luminosity was low, it might have been irreversible because of the formation of highly reflective CO2 clouds, similar to those encountered in climate simulations of early Mars. Our simulations of the early Earth, incorporating the possible formation of such clouds, suggest that the Earth might not be habitable today had it not been warm during the first part of its history. PMID:11540934

Caldeira, K; Kasting, J F

1992-09-17

283

Cloud radiation interaction and the Earth's climate: Relevance to the climate of the Arctic  

International Nuclear Information System (INIS)

The influence on the energy balance of the earth's climate system is reviewed and is based on recent satellite observations of the Earth's Radiation Budget (ERB) and other satellite-derived cloud information. The special difficulties that polar cloudiness poses in analysis of ERB data are discussed. The role of arctic cloudiness on the snow-ice albedo feedback is examined and the possible influence of this feedback to global cloudiness and thus to the radiation balance on the earth are explored

284

A climatic thermostat making Earth habitable  

CERN Document Server

The mean surface temperature on Earth and other planets with atmospheres is determined by the radiative balance between the non-reflected incoming solar radiation and the outgoing long-wave black-body radiation from the atmosphere. The surface temperature is higher than the black-body temperature due to the greenhouse warming. Balancing the ice-albedo cooling and the greenhouse warming gives rise to two stable climate states. A cold climate state with a completelyice-covered planet, called Snowball Earth, and a warm state similar to our present climate where greenhouse warming prevents the total glacition. The warm state has dominated Earth in most of its geological history despite a 30 % fainter young Sun. The warming could have been controlled by a greenhouse thermostat operating by temperature control of the weathering process depleting the atmosphere from $CO_2$. This temperature control has permitted life to evolve as early as the end of the heavy bombartment 4 billion years ago.

Ditlevsen, P D

2005-01-01

285

Balance and Stroke Risk  

Medline Plus

Full Text Available ... a simple balance test could be an important indicator of brain health. He says individuals showing poor ... Follow us on Twitter Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players U.S. National Library of Medicine ...

286

National Energy Balance-1987  

International Nuclear Information System (INIS)

The National Energy Balance - 1987 showns energy fluxes of several primary and secondary energy sources, since the production to final consumption in the main economic sectors, since 1971 to 1986. (E.G.)

287

Energy Balance and Obesity  

Science.gov (United States)

Studies of energy balance and obesity as they relate to cancer. Aspects include the effects of body mass index (BMI), body composition (waist circumference, etc) dietary intake, and physical activity.

288

National Energy Balance - 1985  

International Nuclear Information System (INIS)

The National Energy Balance - 1985 shows energy fluxes of several primary and secondary energy sources, since the production to the final consumption in the main economic sectors, since 1974 to 1984 (E.G.)

289

Balanced-bellows spirometer  

Science.gov (United States)

Compact balanced-bellows dry type spirometer was designed to be insensitive to acceleration fields along any or all coordinate axes. It provides true indication of respiratory action of test subject without need for calibration in acceleration fields.

Holden, G. G.; Smith, J. R., Jr.

1972-01-01

290

Balance and Stroke Risk  

Medline Plus

Full Text Available ... asked to stand on one leg with their eyes open while researchers timed them. Then they had ... test could be an important indicator of brain health. He says individuals showing poor balance on one ...

291

National Energy Balance - 1984  

International Nuclear Information System (INIS)

The National Energy Balance - 1984 shows energy fluxes of several primary and secondary energy sources, since the productions to final consumption in the main economic sectors, since 1973 to 1983. (E.G.)

292

Research of Human Postural Balance Parameters  

Directory of Open Access Journals (Sweden)

Full Text Available In present article postural balance between subjects with stroke and healthy subjects, is being investigated with eyes opened and eyes closed. In the research participated 30 healthy subjects and 15 subjects with stroke. At the same time two experimental measurements were performed – postural balance was measured using balance platform and oscillations of the centre of mass were observed using two-axial accelerometer. It was noted, that amplitudes of subjects with stroke were larger almost two times than control group’s of healthy subjects. It was find out, that ratios of pressure distribution on both left and right legs are in range from 1 to 0.9 for healthy subjects, and ratios below 0.9 are common for subjects with stroke. When subjects were standing with eyes closed, sway amplitudes were higher and the ratios of load distribution on left and right legs were lower.Article in Lithuanian

Julius Griškevi?ius

2011-02-01

293

Judicial Checks and Balances  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the Anglo?American constitutional tradition, judicial checks and balances are often seen as crucial guarantees of freedom. Hayek distinguishes two ways in which the judiciary provides such checks and balances: judicial independence and constitutional review. We create a new database of constitutional rules in 71 countries that reflect these provisions. We find strong support for the proposition that both judicial independence and constitutional review are associated with greater freedom....

La Porta, Rafael; Lopez-de-silanes, Florencio; Pop-eleches, Cristian; Shleifer, Andrei

2004-01-01

294

Power balance in highly loaded fluorescent lamps  

International Nuclear Information System (INIS)

Discrepancies reported in the literature between numerical predictions and experimental measurements in low-pressure Hg discharges at high current densities are considered. Elements of a one-dimensional fluid model and recent spectroscopic and Langmuir probe measurements are combined in a semi-empirical way to individually examine components of the positive column power balance and the discharge conductivity. At a Hg vapour pressure of 0.81 Pa (6.1 mTorr) and a current density of 300 mA cm-2, previous discrepancies in the power balance and discharge conductivity are simultaneously resolved by assuming a higher electron density than that obtained from the Langmuir probe measurements. This conclusion is supported by independent measurements of ion density reported in a companion paper. The importance of radial cataphoresis under these conditions, particularly with regard to radiation transport, is highlighted. This work is of particular interest for the design of fluorescent lamps operating at high current densities

295

Power balance in highly loaded fluorescent lamps  

Energy Technology Data Exchange (ETDEWEB)

Discrepancies reported in the literature between numerical predictions and experimental measurements in low-pressure Hg discharges at high current densities are considered. Elements of a one-dimensional fluid model and recent spectroscopic and Langmuir probe measurements are combined in a semi-empirical way to individually examine components of the positive column power balance and the discharge conductivity. At a Hg vapour pressure of 0.81 Pa (6.1 mTorr) and a current density of 300 mA cm{sup -2}, previous discrepancies in the power balance and discharge conductivity are simultaneously resolved by assuming a higher electron density than that obtained from the Langmuir probe measurements. This conclusion is supported by independent measurements of ion density reported in a companion paper. The importance of radial cataphoresis under these conditions, particularly with regard to radiation transport, is highlighted. This work is of particular interest for the design of fluorescent lamps operating at high current densities.

Lister, G G [Osram Sylvania, 71 Cherry Hill Drive, Beverly, MA 01915 (United States); Curry, J J [National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899-8422 (United States); Lawler, J E [Department of Physics, University of Wisconsin, 1150 University Avenue, Madison, WI 53706 (United States)

2004-11-21

296

Power balance in highly loaded fluorescent lamps  

Science.gov (United States)

Discrepancies reported in the literature between numerical predictions and experimental measurements in low-pressure Hg discharges at high current densities are considered. Elements of a one-dimensional fluid model and recent spectroscopic and Langmuir probe measurements are combined in a semi-empirical way to individually examine components of the positive column power balance and the discharge conductivity. At a Hg vapour pressure of 0.81 Pa (6.1 mTorr) and a current density of 300 mA cm-2, previous discrepancies in the power balance and discharge conductivity are simultaneously resolved by assuming a higher electron density than that obtained from the Langmuir probe measurements. This conclusion is supported by independent measurements of ion density reported in a companion paper. The importance of radial cataphoresis under these conditions, particularly with regard to radiation transport, is highlighted. This work is of particular interest for the design of fluorescent lamps operating at high current densities.

Lister, G. G.; Curry, J. J.; Lawler, J. E.

2004-11-01

297

Rolling-Convolute Joint For Pressurized Glove  

Science.gov (United States)

Rolling-convolute metacarpal/finger joint enhances mobility and flexibility of pressurized glove. Intended for use in space suit to increase dexterity and decrease wearer's fatigue. Also useful in diving suits and other pressurized protective garments. Two ring elements plus bladder constitute rolling-convolute joint balancing torques caused by internal pressurization of glove. Provides comfortable grasp of various pieces of equipment.

Kosmo, Joseph J.; Bassick, John W.

1994-01-01

298

Characteristic of VHF plasma produced by balanced power feeding  

International Nuclear Information System (INIS)

The characteristics of a VHF hydrogen plasma produced by a balanced power feeding method were examined using a two-dimensional hybrid model. The simulation results showed that the electron density peaks at a certain pressure inside the discharge electrodes and significantly decreases outside the electrodes for high gas pressure. In addition, the power absorption efficiency inside the electrodes was improved by increasing the gas pressure. On the other hand, the plasma was produced within the electrodes for low applied voltages.

299

The Spiritual Imperative of Native Epistemology: Restoring Harmony and Balance to Education.  

Science.gov (United States)

Examines the spiritual imperative of Native epistemology with the aim of restoring harmony and balance to education for all people. Focuses on the Sacred Circle, which speaks to all life's interconnectedness; Mother Earth, which speaks to man's sense of place and connection to the earth; and Elders, who connect people to their past and their…

Hanohano, Peter

1999-01-01

300

Extraordinary hall balance.  

Science.gov (United States)

Magnetoresistance (MR) effects are at the heart of modern information technology. However, future progress of giant and tunnelling MR based storage and logic devices is limited by the usable MR ratios of currently about 200% at room-temperature. Colossal MR structures, on the other hand, achieve their high MR ratios of up to 10(6)% only at low temperatures and high magnetic fields. We introduce the extraordinary Hall balance (EHB) and demonstrate room-temperature MR ratios in excess of 31,000%. The new device concept exploits the extraordinary Hall effect in two separated ferromagnetic layers with perpendicular anisotropy in which the Hall voltages can be configured to be carefully balanced or tipped out of balance. Reprogrammable logic and memory is realised using a single EHB element. PACS numbers: 85.75.Nn,85.70.Kh,72.15.Gd,75.60.Ej. PMID:23804036

Zhang, S L; Liu, Y; Collins-McIntyre, L J; Hesjedal, T; Zhang, J Y; Wang, S G; Yu, G H

2013-01-01

 
 
 
 
301

Balanced Modulation for Nonvolatile Memories  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a practical writing/reading scheme in nonvolatile memories, called balanced modulation, for minimizing the asymmetric component of errors. The main idea is to encode data using a balanced error-correcting code. When reading information from a block, it adjusts the reading threshold such that the resulting word is also balanced or approximately balanced. Balanced modulation has suboptimal performance for any cell-level distribution and it can be easily imp...

Zhou, Hongchao; Anxiao; Jiang(?, Jhih-Hang, ??); Bruck, Jehoshua

2012-01-01

302

Finding Your Balance  

CERN Document Server

Balance isn't an issue of time, but an issue of choice. It's about living your values by aligning your behavior with what you believe is really important. Aligning your behavior with your values is much like any other developmental experience; the basic process involves assessment, challenge, and support. You need to determine where you are, define where you want to go, and then put into place the tools you need to get there.Balance is about more than how you spend your time. It's about how you live your life. It's about recognizing that you have control over the choices you make and aligning

(CCL), Center for Creative Leadership; Patterson, Gordon

2011-01-01

303

Getting the balance right  

International Nuclear Information System (INIS)

This 8 page leaflet is published by the Nuclear Electricity Information Group (NEIG) which is made up of eight different bodies working within the nuclear industry. It aims to present a balanced outline of the facts needed to form an opinion about energy policy in the UK. It looks at the price of electricity, other sources of electricity, (oil and coal, solar power, wind power, water power), safety in the nuclear industry, nuclear waste disposal and risks from radiation. The NEIG is in favour of a balanced energy programme with nuclear energy being only a part of the overall scheme. (U.K.)

304

Rotary and Magnus balances  

Science.gov (United States)

Two wind tunnel techniques for determining part of the aerodynamic information required to describe the dynamic bahavior of various types of vehicles in flight are described. Force and moment measurements are determined with a rotary-balance apparatus in a coning motion and with a Magnus balance in a high-speed spinning motion. Coning motion is pertinent to both aircraft and missiles, and spinning is important for spin stabilized missiles. Basic principles of both techniques are described, and specific examples of each type of apparatus are presented. Typical experimental results are also discussed.

Malcolm, G. N.

1981-01-01

305

Earth-Sun Geometry - Earth Revolution Animation  

Science.gov (United States)

The representation is an animation of the Earth revolving around the sun. The Earth is shown as a solid green sphere with the equator and arctic circle marked with black lines and the dark side of the Earth shaded. The Earth's axis is shown with a red line. As the Earth revolves around the sun, the axis is shown to always be pointing in the same direction. The positions of Earth at the winter solstice, vernal equinox, summer solstice, and autumnal equinox are labeled.

Dr. Michael Pidwirny

306

Evapotranspiration Estimation with Remote Sensing and Various Surface Energy Balance Algorithms—A Review  

Digital Repository Infrastructure Vision for European Research (DRIVER)

With the advent of new satellite technology, the radiative energy exchanges between Sun, Earth, and space may now be quantified accurately. Nevertheless, much less is known about the magnitude of the energy flows within the climate system and at the Earth’s surface, which cannot be directly measured by satellites. This review surveys the basic theories, observational methods, and different surface energy balance algorithms for estimating evapotranspiration (ET) from landscapes and regions w...

Yuei-An Liou; Sanjib Kumar Kar

2014-01-01

307

Grid Computing for Earth Science  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The fundamental challenges facing humankind at the beginning of the 21st century require an effective response to the massive changes that are putting increasing pressure on the environment and society. The worldwide Earth science community, with its mosaic of disciplines and players (academia, industry, national surveys, international organizations, and so forth), provides a scientific basis for addressing issues such as the development of new energy resources; a secure water supply; safe st...

Renard, Philippe; Badoux, Vincent; Petitdidier, Monique; Cossu, Roberto

2009-01-01

308

Operational water balance in irrigation districts  

Science.gov (United States)

In pressure irrigation-water distribution networks, applied water volume is usually controlled opening a valve during a calculated time interval, and assuming constant flow rate. In general, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of pressure conditions. A pressure regulating valve PRV is the commonly used pressure regulating device in a hydrant, which, also, executes the open and close function. A hydrant feeds several irrigation units, requiring a wide range in flow rate. In addition, some flow meters are also available, one as a component of the hydrant and the rest are placed downstream. Every land owner has one flow meter for each group of field plots downstream the hydrant. Ideal PRV performance would maintain a constant downstream pressure. However, the true performance depends on both upstream pressure and the discharged flow rate. Theoretical flow rates values have been introduced into a validated in laboratory PRV performance model coupled with an irrigation district waterworks. Variations on flow rate are simulated by taking into account the consequences of variations on climate conditions and also decisions in irrigation operation, such us duration and frequency application. The model comprises continuity, dynamic and energy equations of the components of both the PRV and the water distribution network. In this work the estimation of water balance terms during the irrigation events in an irrigation campaign has been carried on. The effect of demand concentration peaks has been assessed.

Sánchez, Raúl; Rodríguez-Sinobas, Leonor; Juana, Luis; Laguna, Francisco V.

2014-05-01

309

Clouds and the Earth's Radiant Energy System  

Science.gov (United States)

The Clouds and the Earth's Radiant Energy System (CERES) is a key component of the Earth Observing System (EOS) program. The CERES instrument provides radiometric measurements of the Earth's atmosphere from three broadband channels. The CERES missions are a follow-on to the successful Earth Radiation Budget Experiment (ERBE) mission. The first CERES instrument (PFM) was launched on November 27, 1997, as part of the Tropical Rainfall Measuring Mission (TRMM). Two CERES instruments (FM1 and FM2) were launched into polar orbit on board the EOS flagship Terra on December 18, 1999, and two additional CERES instruments (FM3 and FM4) were launched on board EOS Aqua on May 4,2002. [Mission Objectives] The scientific justification for the CERES measurements can be summarized by three assertions: (1) changes in the radiative energy balance of the Earth-atmosphere system can cause long-term climate changes (e.g., carbon dioxide inducing global warming); (2) besides the systematic diurnal and seasonal cycles of incoming solar energy, changes in cloud properties (amount, height, optical thickness) cause the largest changes of the Earth's radiative energy balance; and (3) cloud physics is one of the weakest components of current climate models used to predict potential global climate change. CERES has four main objectives: 1) For climate change analysis, provide a continuation of the ERBE record of radiative fluxes at the top of the atmosphere (TOA), analyzed using the same algorithms that produced the ERBE data. 2) Double the accuracy of estimates of radiative fluxes at TOA and the Earth's surface. 3) Provide the first long-term global estimates of the radiative fluxes within the Earth's atmosphere. 4) Provide cloud property estimates that are consistent with the radiative fluxes from surface to TOA. [Temporal_Coverage: Start_Date=1997-12-27; Stop_Date=] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

310

Multidimensional spectral load balancing  

Science.gov (United States)

A method of and apparatus for graph partitioning involving the use of a plurality of eigenvectors of the Laplacian matrix of the graph of the problem for which load balancing is desired. The invention is particularly useful for optimizing parallel computer processing of a problem and for minimizing total pathway lengths of integrated circuits in the design stage.

Hendrickson, Bruce A. (Albuquerque, NM); Leland, Robert W. (Albuquerque, NM)

1996-12-24

311

1992 provisional energy balance  

International Nuclear Information System (INIS)

This paper gives a provisional energy balance in France in 1992. After a brief study of economical and energy context in world wide, this paper gives informations about energy dependence ratio and evolutions of energy sources (electric power, coal, petroleum, natural gas), evolution of energy consumption. 1 fig,. 4 tab

312

National energy balance - 1978  

International Nuclear Information System (INIS)

The national energy balance of 1978 shows some modifications in relation to the last year. New tables were included aiming to show the brazilian energy situation, such as the hydraulic potential and the non-renewable energy resources. (E.G.)

313

National Energy Balance - 1981  

International Nuclear Information System (INIS)

The National Energy Balance - 1981, shows a new metodology and information in level of several economic sectors, as well as a separation of primary and secondary energy sources, its energy fluxes, i.e. production, imports, exports, consumption, etc...(E.G.)

314

National energy balance - 1977  

International Nuclear Information System (INIS)

The national energy balance of the 1976 shows several modifications in relation to the last year. The historical serie is based in more confiable information, from several energy companies. The most greater modifications are on energy source of hard control, such as lignite and charcoal for non-siderurgic uses. (E.G.)

315

Balancing through episodic learning  

DEFF Research Database (Denmark)

Peter Jarvis’s theory about learning suggests that human beings learn and change as a result of hearing, seeing, smelling, tasting, touching, and feeling. They change and learn by interacting with other humans, things, and events in certain time-space contexts and by reflecting upon these, as well as upon wished-for future states or past experiences, knowledge, and history, and upon what these experiences mean to one’s own self and identity. This chapter explores how female top managers have to reflect and find a balance in their work-family lives on the basis of interaction with, and inputs from, all these human and nonhuman elements. It shows how they have to overcome relational inertia related to all of them in order to succeed in obtaining such a balance. If a certain degree of balance between elements is achieved at work, as well as on the home front, the female top manager may experience being in a state of balance.

Scheuer, John Damm

2013-01-01

316

National Energy Balance - 1986  

International Nuclear Information System (INIS)

The National Energy Balance - 1986 shows energy fluxes of several primary and secondary energy sources, since the production to the final consumption in the main economic sectors, since 1970 to 1985. The incorporation of a new brazilian information is done. (E.G.)

317

Earth Science Lessons  

Science.gov (United States)

This collection of Earth Science lessons, tests, and activities for middle school students is an accompaniment to the Volcano World website. Topics covered include plate tectonics, Pangea, plate movement, Earth layers, earthquakes, volcanoes, rocks and minerals, and prehistoric Earth.

Johnson, Scott

318

Wind-Tunnel Balance Characterization for Hypersonic Research Applications  

Science.gov (United States)

Wind-tunnel research was recently conducted at the NASA Langley Research Center s 31-Inch Mach 10 Hypersonic Facility in support of the Mars Science Laboratory s aerodynamic program. Researchers were interested in understanding the interaction between the freestream flow and the reaction control system onboard the entry vehicle. A five-component balance, designed for hypersonic testing with pressurized flow-through capability, was used. In addition to the aerodynamic forces, the balance was exposed to both thermal gradients and varying internal cavity pressures. Historically, the effect of these environmental conditions on the response of the balance have not been fully characterized due to the limitations in the calibration facilities. Through statistical design of experiments, thermal and pressure effects were strategically and efficiently integrated into the calibration of the balance. As a result of this new approach, researchers were able to use the balance continuously throughout the wide range of temperatures and pressures and obtain real-time results. Although this work focused on a specific application, the methodology shown can be applied more generally to any force measurement system calibration.

Lynn, Keith C.; Commo, Sean A.; Parker, Peter A.

2012-01-01

319

Motor mechanisms of balance during quiet standing.  

Science.gov (United States)

The purpose of this paper is to highlight the motor mechanisms involved in balance as the human, as a biped, continuously defends against gravitational and internal forces to maintain a safe posture. The search for these mechanisms needs precise and valid 3D measurements including both limbs plus valid biomechanical models. The literature shows the need for two force platforms to separate the mechanisms at the ankle and hip (load/unload mechanism). Also, precise measures ( approximately 0.03 mm) of markers on a multi-segment 3D bilateral model are required to record the minute trajectories of all segments and joints. The controlled variable, center-of-mass, is seen to be virtually in phase with the controlling variable, the center-of-pressure, which suggests a 0th order system where a simple series elastic spring could maintain balance. The first model involves a mass/spring/damper of medial/lateral balance: the stiffness was varied with stance width and the predicted sway from a spring controlled inverted pendulum closely matched the experimentally measured stiffness and sway. The second was a non-linear model of the plantarflexor series elastic elements which resulted in three closely validated predictions of anterior/posterior balance: the locus of the gravitational load line, the predicted ankle moment and the ankle stiffness at the operating point. PMID:12488086

Winter, David A; Patla, Aftab E; Ishac, Milad; Gage, William H

2003-02-01

320

Breaking of balanced and unbalanced equatorial waves.  

Science.gov (United States)

A clear-cut signature of a wave-breaking event is irreversible modification of the mean flow. In this paper, we provide examples of different breaking mechanisms and show that breaking scenario of equatorial waves in the beta-plane shallow water model is determined by the degree of balance between the zonal component of the Coriolis force and the pressure gradient. Our analysis is based on a specially designed numerical method which guarantees two essential conditions to simulate nonlinear equatorial waves: (i) the scheme converges toward weak solutions including shocks and (ii) preserves the steadiness of balanced stationary solutions. This allows for accurate diagnostics of Lagrangian invariants of motion such as passive tracer density or potential vorticity. For unbalanced waves, the lack of balance leads to shock formation in finite time. In shock fronts, the variation of the dissipation rate induces a nonadvective potential vorticity flux and violates the local potential vorticity conservation valid for smooth solutions. This dissipative breaking mechanism is generic for unbalanced waves and is associated with enhanced mixing. For long, balanced (Rossby) waves, breaking consists in appearance of recirculation regions. It results in the formation of propagating patterns, the equatorial modons, which trap fluid particles. Such breaking occurs during the propagation of Rossby wave packets with positive geopotential anomaly and is strengthened by decreasing fluid depth. The modons are robust and collide quasielastically with Kelvin waves. PMID:15836268

Bouchut, F; Le Sommer, J; Zeitlin, V

2005-03-01

 
 
 
 
321

The earth's radius and the G variation  

International Nuclear Information System (INIS)

It has been assumed that if the gravitational constant G was larger in the past, the Earth's radius had to be smaller. The assertion holds provided the input from microphysics (in particular the equation of state) is independent of G. While this is true for some theories of gravity with variable G it is not so in the scale covariant theory, where the pressure can be affected by a variable G in a way that, for a constant mass of the Earth, a larger G in the past implies a larger Earth's radius. Comparison with recent palaeomagnetic data is presented. (author)

322

Exercise to Improve Your Balance  

Science.gov (United States)

... Balance Having good balance is important for many everyday activities, such as going up and down the stairs. It also helps you walk safely and avoid tripping and falling over objects in your way. Each year, more than 2 ...

323

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... They thought I was getting senile because the vertigos -- it upset my balance completely. Narrator: These people ... person with a balance disorder might have are vertigo -- or a feeling as if you or the ...

324

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... The tiny nerve fibers collect and join to form the vestibular, or balance, nerves. The balance nerve ... or the things around you are spinning -- dizziness, light-headedness, and blurred vision. Some people also experience ...

325

Quasirandom Load Balancing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a simple distributed algorithm for balancing indivisible tokens on graphs. The algorithm is completely deterministic, though it tries to imitate (and enhance) a random algorithm by keeping the accumulated rounding errors as small as possible. Our new algorithm surprisingly closely approximates the idealized process (where the tokens are divisible) on important network topologies. On d-dimensional torus graphs with n nodes it deviates from the idealized process ...

Friedrich, Tobias; Gairing, Martin; Sauerwald, Thomas

2010-01-01

326

Balance-bot  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Research on inverted pendulum has gained momentum over the last decade on a number of robotic laboratories over the world; due to its unstable proprieties is a good example for control engineers to verify a control theory. To verify that the pendulum can balance we can make some simulations using a closed-loop controller method such as the linear quadratic regulator or the proportional–integral–derivative method. Also the idea of robotic teleoperation is gaining ground. Con...

Abreu, Victor Vicente

2009-01-01

327

National energy balance - 1976  

International Nuclear Information System (INIS)

Based on available data from IBGE, CNP/Petrobras, Eletrobras, Nuclebras and other governmental enterprises the National Energy Balance was done. This publication covers since 1965 to 1975. In conformity to the international rules, the energy resources used for non-energy purposes were excluded. The energy production and consumption for the next ten years were forecasted, considering the actual brazilian energy policy. (E.G.)

328

Extraordinary hall balance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Magnetoresistance (MR) effects are at the heart of modern information technology. However, future progress of giant and tunnelling MR based storage and logic devices is limited by the usable MR ratios of currently about 200% at room-temperature. Colossal MR structures, on the other hand, achieve their high MR ratios of up to 106% only at low temperatures and high magnetic fields. We introduce the extraordinary Hall balance (EHB) and demonstrate room-temperature MR ratios in excess of 31,000%....

Zhang, S. L.; Liu, Y.; Collins-mcintyre, L. J.; Hesjedal, T.; Zhang, J. Y.; Wang, S. G.; Yu, G. H.

2013-01-01

329

Simple Cell Balance Circuit  

Science.gov (United States)

A method has been developed for continuous cell voltage balancing for rechargeable batteries (e.g. lithium ion batteries). A resistor divider chain is provided that generates a set of voltages representing the ideal cell voltage (the voltage of each cell should be as if the cells were perfectly balanced). An operational amplifier circuit with an added current buffer stage generates the ideal voltage with a very high degree of accuracy, using the concept of negative feedback. The ideal voltages are each connected to the corresponding cell through a current- limiting resistance. Over time, having the cell connected to the ideal voltage provides a balancing current that moves the cell voltage very close to that ideal level. In effect, it adjusts the current of each cell during charging, discharging, and standby periods to force the cell voltages to be equal to the ideal voltages generated by the resistor divider. The device also includes solid-state switches that disconnect the circuit from the battery so that it will not discharge the battery during storage. This solution requires relatively few parts and is, therefore, of lower cost and of increased reliability due to the fewer failure modes. Additionally, this design uses very little power. A preliminary model predicts a power usage of 0.18 W for an 8-cell battery. This approach is applicable to a wide range of battery capacities and voltages.

Johnson, Steven D.; Byers, Jerry W.; Martin, James A.

2012-01-01

330

Modeling Early Earth Climate with GEEBITT  

Science.gov (United States)

In this activity, students gain experience using a spreadsheet and working with others to decide how to conduct their model 'experiments' with the NASA GEEBITT (Global Equilibrium Energy Balance Interactive Tinker Toy). While becoming more familiar with the physical processes that made Earth's early climate so different from that of today, they also acquire first-hand experience with a limitation in modeling, specifically, parameterization of critical processes.

Shellito, Cindy; On the Cutting Edge Collection - Science Education Resource Center (SERC) at Carleton College

331

Spreadsheet eases heat balance, payback calculations  

International Nuclear Information System (INIS)

This paper reports that a generalized Lotus type spreadsheet program has been developed to perform the heat balance and simple payback calculations for various turbine-generator (TG) inlet steam pressures. It can be used for potential plant expansions or new cogeneration installations. The program performs the basic heat balance calculations that are associated with turbine-generator, feedwater heating process steam requirements and desuperheating. The printout, shows the basic data and formulation used in the calculations. The turbine efficiency data used are applicable for automatic extraction turbine-generators in the 30-80 MW range. Simple payback calculations are for chemical recovery boilers and power boilers used in the pulp and paper industry. However, the program will also accommodate boilers common to other industries

332

Toward an internally consistent pressure scale  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Our ability to interpret seismic observations including the seismic discontinuities and the density and velocity profiles in the earth's interior is critically dependent on the accuracy of pressure measurements up to 364 GPa at high temperature. Pressure scales based on the reduced shock-wave equations of state alone may predict pressure variations up to 7% in the megabar pressure range at room temperature and even higher percentage at high temperature, leading to large uncertainties in under...

Fei, Yingwei; Ricolleau, Angele; Frank, Mark; Mibe, Kenji; Shen, Guoyin; Prakapenka, Vitali

2007-01-01

333

Earth Observatory Glossary  

Science.gov (United States)

The Earth Observatory Glossary defines words from space science, ecology and Earth science. It is part of the NASA Earth Observatory site, which provides new satellite imagery and scientific information about Earth with a focus on climate and environmental change. The new glossary mode allows users to browse the Earth Observatory site with special terms highlighted that, when selected, will take you to the appropriate entry in the glossary.

334

Earth, Earth's Moon and Mars Balloons  

Science.gov (United States)

This is an activity about planetary sizes and distances. Learners will construct a scale model of the Earth, Earth’s Moon and Mars in relation to each other using balloons. They will use this model to predict distances and reflect on how scientists use models to construct explanations through the scientific process. The lesson models scientific inquiry using the 5E instructional model and includes teacher notesand vocabulary.

335

Balance ability and athletic performance.  

Science.gov (United States)

The relationship between balance ability and sport injury risk has been established in many cases, but the relationship between balance ability and athletic performance is less clear. This review compares the balance ability of athletes from different sports, determines if there is a difference in balance ability of athletes at different levels of competition within the same sport, determines the relationship of balance ability with performance measures and examines the influence of balance training on sport performance or motor skills. Based on the available data from cross-sectional studies, gymnasts tended to have the best balance ability, followed by soccer players, swimmers, active control subjects and then basketball players. Surprisingly, no studies were found that compared the balance ability of rifle shooters with other athletes. There were some sports, such as rifle shooting, soccer and golf, where elite athletes were found to have superior balance ability compared with their less proficient counterparts, but this was not found to be the case for alpine skiing, surfing and judo. Balance ability was shown to be significantly related to rifle shooting accuracy, archery shooting accuracy, ice hockey maximum skating speed and simulated luge start speed, but not for baseball pitching accuracy or snowboarding ranking points. Prospective studies have shown that the addition of a balance training component to the activities of recreationally active subjects or physical education students has resulted in improvements in vertical jump, agility, shuttle run and downhill slalom skiing. A proposed mechanism for the enhancement in motor skills from balance training is an increase in the rate of force development. There are limited data on the influence of balance training on motor skills of elite athletes. When the effectiveness of balance training was compared with resistance training, it was found that resistance training produced superior performance results for jump height and sprint time. Balance ability was related to competition level for some sports, with the more proficient athletes displaying greater balance ability. There were significant relationships between balance ability and a number of performance measures. Evidence from prospective studies supports the notion that balance training can be a worthwhile adjunct to the usual training of non-elite athletes to enhance certain motor skills, but not in place of other conditioning such as resistance training. More research is required to determine the influence of balance training on the motor skills of elite athletes. PMID:21395364

Hrysomallis, Con

2011-03-01

336

Distributed Selfish Load Balancing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Suppose that a set of $m$ tasks are to be shared as equally as possible amongst a set of $n$ resources. A game-theoretic mechanism to find a suitable allocation is to associate each task with a ``selfish agent'', and require each agent to select a resource, with the cost of a resource being the number of agents to select it. Agents would then be expected to migrate from overloaded to underloaded resources, until the allocation becomes balanced. Recent work has studied the ...

Berenbrink, P.; Friedetzky, T.; Goldberg, L. A.; Goldberg, P.; Hu, Z.; Martin, R.

2005-01-01

337

Watt and joule balances  

Science.gov (United States)

The time is fast approaching when the SI unit of mass will cease to be based on a single material artefact and will instead be based upon the defined value of a fundamental constant—the Planck constant—h . This change requires that techniques exist both to determine the appropriate value to be assigned to the constant, and to measure mass in terms of the redefined unit. It is important to ensure that these techniques are accurate and reliable to allow full advantage to be taken of the stability and universality provided by the new definition and to guarantee the continuity of the world's mass measurements, which can affect the measurement of many other quantities such as energy and force. Up to now, efforts to provide the basis for such a redefinition of the kilogram were mainly concerned with resolving the discrepancies between individual implementations of the two principal techniques: the x-ray crystal density (XRCD) method [1] and the watt and joule balance methods which are the subject of this special issue. The first three papers report results from the NRC and NIST watt balance groups and the NIM joule balance group. The result from the NRC (formerly the NPL Mk II) watt balance is the first to be reported with a relative standard uncertainty below 2 × 10-8 and the NIST result has a relative standard uncertainty below 5 × 10-8. Both results are shown in figure 1 along with some previous results; the result from the NIM group is not shown on the plot but has a relative uncertainty of 8.9 × 10-6 and is consistent with all the results shown. The Consultative Committee for Mass and Related Quantities (CCM) in its meeting in 2013 produced a resolution [2] which set out the requirements for the number, type and quality of results intended to support the redefinition of the kilogram and required that there should be agreement between them. These results from NRC, NIST and the IAC may be considered to meet these requirements and are likely to be widely debated prior to a decision on redefinition. The CCM had already recognized that agreement was close and has set in place a process whereby redefinition can take place by 2018. The final decision will be in the hands of the Conférence Générale des Poids et Mesures (CGPM) but the results reported here should aid a positive decision. Figure 1. Figure 1. Results from recent measurements of the Planck constant. The reference for the results h 90 is derived from the conventional values of the Josephson constant K J-90 and the von Klitzing constant R K-90. The factor of ten improvement in uncertainty of the NRC watt balance result, over that achieved by the same apparatus at NPL a few years earlier, can be understood as a factor of five improvement arising from the elimination of an effect discovered at NPL that could not be eliminated before shipment to Canada and a factor of two arising from the considerable improvements made by NRC. Once the kilogram has been redefined, the watt and joule balances will complete their transitions from instruments that are primarily of interest to the electrical community for determining the SI electrical units from the mechanical units, to the principal methods by which an individual National Measurement Institute (NMI) can make an independent determination of the SI unit of mass and thereby contribute to the maintenance of national and international mass scales. This special issue gives an introduction to the diversity of techniques which are required for the operation of watt and joule balances. However it does not contain a review of existing balances; this was a deliberate decision, as a number of such review papers have been published in the past five years [3-7] and it was felt that it was not yet time for another. The first technique considered is that of gravimetry; the watt balance measures the weight Mg of a mass M , and to convert the measured weight into a mass, the value of the acceleration due to gravity g must be known, at the time of the weighing and at the centre of gravity of the mass. The paper by Liard and his co-au

Robinson, Ian A.

2014-04-01

338

On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth’s Radiant Energy Balance  

Directory of Open Access Journals (Sweden)

Full Text Available The sensitivity of the climate system to an imposed radiative imbalance remains the largest source of uncertainty in projections of future anthropogenic climate change. Here we present further evidence that this uncertainty from an observational perspective is largely due to the masking of the radiative feedback signal by internal radiative forcing, probably due to natural cloud variations. That these internal radiative forcings exist and likely corrupt feedback diagnosis is demonstrated with lag regression analysis of satellite and coupled climate model data, interpreted with a simple forcing-feedback model. While the satellite-based metrics for the period 2000–2010 depart substantially in the direction of lower climate sensitivity from those similarly computed from coupled climate models, we find that, with traditional methods, it is not possible to accurately quantify this discrepancy in terms of the feedbacks which determine climate sensitivity. It is concluded that atmospheric feedback diagnosis of the climate system remains an unsolved problem, due primarily to the inability to distinguish between radiative forcing and radiative feedback in satellite radiative budget observations.

Roy W. Spencer

2011-07-01

339

14 CFR 23.421 - Balancing loads.  

Science.gov (United States)

...2010-01-01 2010-01-01 false Balancing loads. 23.421 Section 23.421 Aeronautics...and Balancing Surfaces § 23.421 Balancing loads. (a) A horizontal surface balancing load is a load necessary to maintain...

2010-01-01

340

26 CFR 1.430(f)-1 - Effect of prefunding balance and funding standard carryover balance.  

Science.gov (United States)

...prefunding balance and funding standard carryover balance. 1.430(f)-1 Section...prefunding balance and funding standard carryover balance. (a) In general —(1...application of prefunding and funding standard carryover balances under section...

2010-04-01

 
 
 
 
341

Thermodynamics of the Earth  

International Nuclear Information System (INIS)

Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 x 1012 W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>104 : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical approach to thermal physics, especially thermal expansion and the Grueneisen parameter, invokes insights that have disappeared from view in 'mainstream' physics.

342

Twelve weeks of BodyBalance® training improved balance and functional task performance in middle-aged and older adults  

Directory of Open Access Journals (Sweden)

Full Text Available Vaughan P Nicholson, Mark R McKean, Brendan J Burkett School of Health and Sport Sciences, University of the Sunshine Coast, Sunshine Coast, QLD, Australia Purpose: The purpose of the study was to evaluate the effect of BodyBalance® training on balance, functional task performance, fear of falling, and health-related quality of life in adults aged over 55 years.Participants and methods: A total of 28 healthy, active adults aged 66±5 years completed the randomized controlled trial. Balance, functional task performance, fear of falling, and self-reported quality of life were assessed at baseline and after 12 weeks. Participants either undertook two sessions of BodyBalance per week for 12 weeks (n=15 or continued with their normal activities (n=13.Results: Significant group-by-time interactions were found for the timed up and go (P=0.038, 30-second chair stand (P=0.037, and mediolateral center-of-pressure range in narrow stance with eyes closed (P=0.017. There were no significant effects on fear of falling or self-reported quality of life.Conclusion: Twelve weeks of BodyBalance training is effective at improving certain balance and functional based tasks in healthy older adults. Keywords: postural control, yoga, tai chi, center of pressure, exercise

Nicholson VP

2014-11-01

343

Negative leave balances  

CERN Multimedia

Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1Â September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply. Â Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30Â September and/or 31Â December, leave will automatically be transferred from one account to another on the relevant dates i...

Human Resources Department

2005-01-01

344

Negative leave balances  

CERN Multimedia

Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1 September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply.  Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30 September and/or 31 December, leave will automatically be transferred from one account to another on the relevant dates in or...

Human Resources Department

2005-01-01

345

Tritium particle balance and retention during DT discharges in JET  

International Nuclear Information System (INIS)

The tritium balance based on pressure measurements has been performed on a shot by shot analysis during the plasma operations of the DTE1 campaign carried out at JET in 1997. This gives a complementary analysis to the integrated tritium inventory already reported for a full day of experiments. The particle balance shows that the T flux retention was of the order of about 1.26 1021 T s-1 during the plasma operations (?65% of the injected flux). The outgasing between pulses reduces this T inventory to about 30% of the injection. This detailed gas balance shows also that the retention of hydrogen species depends on the plasma isotopic ratio. However, during the D clean up pulses, the amount of T removed by isotopic exchange is shown to be limited to about 2 1023 particles. Finally, the total particle balance (D+T) is shown to be independent the plasma isotopic ratio. (authors)

346

Deuterium inventory in Tore Supra: Coupled carbon–deuterium balance  

Energy Technology Data Exchange (ETDEWEB)

This paper presents an analysis of the carbon–deuterium circulation and the resulting balance in Tore Supra over the period 2002–2007. Carbon balance combines the estimation of carbon gross erosion from spectroscopy, net erosion and deposition using confocal microscopy, lock-in thermography and SEM, and a measure of the amount of deposits collected in the vacuum chamber. Fuel retention is determined from post-mortem (PM) analyses and gas balance (GB) measurements. Special attention was paid to the deuterium outgassed during the nights and weekends of the experimental campaign (vessel under vacuum, Plasma Facing Components at 120 °C) and during vents (vessel at atmospheric pressure, PFCs at room temperature). It is shown that this outgassing is the main process reconciling the PM and GB estimations of fuel retention, closing the coupled carbon–deuterium balance. In particular, it explains why the deuterium concentration in deposits decreases with increasing depth.

Pégourié, B., E-mail: bernard.pegourie@cea.fr [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Panayotis, S. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Languille, P.; Martin, C. [Laboratoire PIIM, Aix-Marseille Université, CNRS UMR 7345, 13397 Marseille (France); Dittmar, T. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Center for Energy Research, Univ. of California – San Diego, San Diego (United States); Gauthier, E.; Hatchressian, J.-C.; Pascal, J.-Y. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Roubin, P.; Ruffe, R. [Laboratoire PIIM, Aix-Marseille Université, CNRS UMR 7345, 13397 Marseille (France); Tsitrone, E.; Vartanian, S. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Wang, H. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Beauté, A.; Bouvet, J.; Brosset, C.; Bucalossi, J. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); Cabié, M. [Aix-Marseille Univ., CP2M, Marseille (France); Caprin, E.; Courtois, X. [CEA, IRFM, 13108 Saint-Paul-lez-Durance (France); and others

2013-07-15

347

Lattice thermal conductivity of MgO at conditions of Earth’s interior  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thermal conductivity of the Earth’s lower mantle greatly impacts the mantle convection style and affects the heat conduction from the core to the mantle. Direct laboratory measurement of thermal conductivity of mantle minerals remains a technical challenge at the pressure-temperature (P-T) conditions relevant to the lower mantle, and previously estimated values are extrapolated from low P-T data based on simple empirical thermal transport models. By using a numerical technique that combines...

Tang, Xiaoli; Dong, Jianjun

2010-01-01

348

Combined CFD/Population Balance Model for Gas Hydrate Particle Size Prediction in Turbulent Pipeline Flow  

Science.gov (United States)

A combined computational fluid dynamics/population balance model (CFD-PBM) is developed for gas hydrate particle size prediction in turbulent pipeline flow. The model is based on a one-moment population balance technique, which is coupled with flow field parameters computed using commercial CFD software. The model is calibrated with a five-moment, off-line population balance model and validated with experimental data produced in a low-pressure multiphase flow loop.

Balakin, Boris V.; Hoffmann, Alex C.; Kosinski, Pawel; Istomin, Vladimir A.; Chuvilin, Evgeny M.

2010-09-01

349

The effects of load carriage and bracing on the balance of schoolgirls with adolescent idiopathic scoliosis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The balance function of children is known to be affected by carriage of a school backpack. Children with adolescent idiopathic scoliosis (AIS) tend to show poorer balance performance, and are typically treated by bracing, which further affects balance. The objective of this study is to examine the combined effects of school backpack carriage and bracing on girls with AIS. A force platform was used to record center of pressure (COP) motion in 20 schoolgirls undergoing thoraco-lumbar-sacral ort...

Chow, Daniel H. K.; Leung, Dawn S. S.; Holmes, Andrew D.

2007-01-01

350

Data needs for nutrient balances  

DEFF Research Database (Denmark)

One of the tools for evaluating the results of environmental action plans or EU directives related to nutrients in the agricultural sector is to follow the development of annually estimated nitrogen (N) and phosphorus (P) balances and surplus. Unlike greenhouse gas and ammonia emissions, countries are not required to report N and P balances for agriculture as part of any international conventions. As a consequence, there is no organisation equivalent to the Intergovernmental Panel on Climate Change (IPCC) or United Nations Economic Commission for Europe (UNECE) who has responsibility for standardising and improving the methodology to calculate such balances. However, Eurostat and OECD have jointly established a standard for using a gross N balances, and the soil N balance calculated by the CAPRI model has gained acceptance in European policymaking. It can be mentioned that the Task Force on Reactive Nitrogen (TFRN), established under Convention on Long-Range Transboundary Pollution (CLRTP), is currently establishing national N balances that include agriculture.

Vinther, Finn Pilgaard

2011-01-01

351

Energy Balance Models and Planetary Dynamics  

Science.gov (United States)

We know that planetary dynamics can have a significant affect on the climate of planets. Planetary dynamics dominate the glacial-interglacial periods on Earth, leaving a significant imprint on the geological record. They have also been demonstrated to have a driving influence on the climates of other planets in our solar system. We should therefore expect th.ere to be similar relationships on extrasolar planets. Here we describe a simple energy balance model that can predict the growth and thickness of glaciers, and their feedbacks on climate. We will also describe model changes that we have made to include planetary dynamics effects. This is the model we will use at the start of our collaboration to handle the influence of dynamics on climate.

Domagal-Goldman, Shawn

2012-01-01

352

Pressure ulcer  

Science.gov (United States)

... that area. Use pillows, special foam cushions, and sheepskin to reduce the pressure. Treat the sore as ... Use items that can help reduce pressure -- pillows, sheepskin, foam padding, and powders from medical supply stores. ...

353

Study on earth pressure at equilibrium and horizontal subgrade reaction coefficient of an earth wall embedment in braced excavation work on clayey soil; Nenseido jiban ni okeru kussaku dodomeheki neirebu no heiko doatsu to suihei jiban hanryoku keisu ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

Concerning the excavated soil retaining work, examination was conducted about the equilibrium soil pressure and horizontal subgrade reaction coefficient using the finite element method and a formula was proposed including highly sensitive parameters. This formula, conventional calculation method, and values actually measured on site were compared with each other, and it was found that the factors that affect the equilibrium soil pressure are excavation depth, excavation width, coefficient of soil pressure at rest, weight per unit volume of soil, and shear resistance on the soil retaining wall surface, and that the factors that affect the horizontal subgrade reaction coefficient are excavation width, coefficient of soil pressure at rest, penetration depth of the soil retaining wall, and subgrade deformation coefficient. The measurements obtained at an LNG underground tank, where the horizontal displacement of the soil retaining wall is relatively small, were compared with the equilibrium soil pressure and horizontal subgrade reaction coefficient calculated using the proposed formula, and then it was found that there was excellent approximation between them though with a little error. It was concluded that the proposed formula is generally applicable to the calculation of equilibrium soil pressure and horizontal subgrade reaction coefficient, and is good for practical use in excavated soil retaining work. 12 refs., 33 figs., 15 tabs.

Nakamura, H.; Hirashima, K.

1996-03-20

354

Dynamic load balancing of applications  

Science.gov (United States)

An application-level method for dynamically maintaining global load balance on a parallel computer, particularly on massively parallel MIMD computers. Global load balancing is achieved by overlapping neighborhoods of processors, where each neighborhood performs local load balancing. The method supports a large class of finite element and finite difference based applications and provides an automatic element management system to which applications are easily integrated.

Wheat, Stephen R. (Albuquerque, NM)

1997-01-01

355

Are Social Networks Really Balanced?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

There is a long-standing belief that in social networks with simultaneous friendly/hostile interactions (signed networks) there is a general tendency to a global balance. Balance represents a state of the network with lack of contentious situations. Here we introduce a method to quantify the degree of balance of any signed (social) network. It accounts for the contribution of all signed cycles in the network and gives, in agreement with empirical evidences, more weight to th...

Estrada, Ernesto; Benzi, Michele

2014-01-01

356

Pressure ulcers.  

Science.gov (United States)

Pressure sores occur when prolonged pressure or shear is applied to the skin of predisposed patients. Prevention requires identification of patients at risk and institution of thorough surveillance and nursing care. Once pressure ulcers occur, treatment decisions are based on the depth of the ulceration. Management consists of motivating the staff, relieving the pressure, debriding the wound, lowering wound bacterial counts and treating complications. PMID:3565218

Xakellis, G C; Garzone, P

1987-04-01

357

balance del 2007  

Directory of Open Access Journals (Sweden)

Full Text Available La Comisión de Derechos Humanos del Distrito Federal (CDHDF, en el presente artículo, busca realizar un balance de los principales avances, problemáticas y retos que en el ámbito de los derechos humanos se enfrentaron en el 2007. Enmarcados en un hecho sin precedente en el ámbito estatal, se puso en marcha el proceso de construcción del Diagnóstico y Programa de Derechos Humanos del Distrito Federal, esfuerzo que constituye un punto de partida común para instancias públicas, académicas y organismos de la sociedad civil en el DF, que favorecerá directamente a todas las personas que habitan y transitan esta ciudad, y que sin duda constituye una experiencia inédita e innovadora que aspira a convertirse en referente local, nacional e internacional.

Emilio \\u00C1lvarez Icaza

2008-01-01

358

Work-life balance  

Energy Technology Data Exchange (ETDEWEB)

Gay Renouf has opted for a work/life balance; with a chemistry degree she joined the Saskatchewan Research Council out of graduate school in 1986. She first worked on understanding surfactants in emulsions and then dealt more with petroleum engineering issues like pipeline specifications. She is looking at waterfloods in heavy and medium gravity pools and has discovered factors helping to produce heavy oil waterfloods. But all Renouf's life is not devoted to her work: she has been working part-time, spending her free time being a parent, training for marathons and being a running coach. Renouf believes that her passion for running is consistent with her work as a scientist.

Roche, Pat

2011-03-15

359

Museum of the Earth  

Science.gov (United States)

The Museum of the Earth is a natural history museum that stresses the interdependence of the Earth and its life, fostering public understanding of the environment and Earth's past, present and future. The museum is an exhibit facility for one of the nation's largest fossil collections, providing a resource for the public, teachers and students. It serves regional and national audiences by disseminating educational materials as well as promoting best practices and collaboration among providers of informal Earth system education.

2006-08-14

360

Sun-Earth Viewer  

Science.gov (United States)

The Sun-Earth Viewer is an experimental Flash-based viewer that allows visitors to zoom and pan live NASA solar and Earth images. In addition, it features video interviews with scientists and detailed scientific animations, extensive interactive sun-earth illustrations, and live interactive solar and aurora images.

 
 
 
 
361

The fate of Earth’s ocean  

Directory of Open Access Journals (Sweden)

Full Text Available Questions of how water arrived on the Earth’s surface, how much water is contained in the Earth system as a whole, and how much water will be available in the future in the surface reservoirs are of central importance to our understanding of the Earth. To answer the question about the fate of the Earth’s ocean, one has to study the global water cycle under conditions of internal and external forcing processes. Modern estimates suggest that the transport of water to the surface is five times smaller than water movement to the mantle, so that the Earth will lose all its sea-water in one billion years from now. This straightforward extrapolation of subduction-zone fluxes into the future seems doubtful. Using a geophysical modelling approach it was found that only 27% of the modern ocean will be subducted in one billion years. Internal feedbacks will not be the cause of the ocean drying out. Instead, the drying up of surface reservoirs in the future will be due to the increase in temperature caused by a maturing Sun connected to hydrogen escape to outer space. Keywords: Surface water reservoir, water fluxes, regassing, degassing, global water cycle

C. Bounama

2001-01-01

362

Modelling evapotranspiration using the surface energy balance systems (sebs) and landsat tm data (rabat region, morocco)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Modelling and understanding the surface energy balance is important for assessing the re-distribution of moisture and heat in soil and atmosphere. The Surface Energy Balance System (SEBS) estimates turbulent heat fluxes using satellite earth observation data in the visible, near infrared, and thermal spectral domain. SEBS is capable of estimating atmospheric turbulent fluxes and surface evaporation from point to continental scale with reasonable accuracy. Validation of SEBS has been done on a...

Kwast, J.; Jong, S. M.

2004-01-01

363

Pre-onset Azimuthal Pressure Gradient and Associated Auroral Intensifications Related to Dipolarization Fronts  

Science.gov (United States)

The plasma pressure spatial distribution and the magnetic field in force balance with it determine the distribution of the Field-Aligned Current (FAC) in the quasi-static near-Earth plasma sheet. The time evolution of the azimuthal plasma pressure gradient during undisturbed periods is of particular importance in leading to the evolution of FACs, which strongly affect the ionospheric current circulation and the aurora formation before dynamical processes strike, e.g., substorms. Xing et al. (2011) demonstrated by case study that the plasma sheet pressure gradient at ~11 RE near the substorm onset meridian undergoes a substantial duskward enhancement shortly before the onset as identified from the auroral poleward expansion. The increased upward FAC driven by this pressure gradient enhancement leads to the thin onset arc intensification from which the poleward expansion initiates. The mechanism of the formation of such a transient duskward pressure gradient is still an open question. In the present study, we employ the multi-THEMIS spacecraft in azimuthal conjunction -at ~-11 RE and examine the ion flux and distributions during the period of pressure gradient enhancement. Strong field-aligned ion flux enhancements covering the energy range from several KeV to above 25KeV were observed by the spacecraft identifying the higher pressure increase, while at the same time the ion distributions show substantial field-aligned, mushroom-like shift in velocity space. These resemble the ion acceleration ahead of earthward moving dipolarization fronts in a highly stretched magnetic field during the late growth phase. The local plasma develops strong transient parallel anisotropy due to the ion acceleration. On the other hand, the spacecraft observing the lower pressure increase found weaker or no ion flux enhancements and had nearly isotropic distributions. Due to these spatial differences, similar transient pressure gradient enhancements in the dawnward direction were also found for some events. These suggest that the transient azimuthal pressure gradient enhancement near the onset meridian could result from the azimuthal difference of the ion acceleration caused by the localized dipolarization fronts that reach the near-Earth plasma sheet at the onset meridian. The associated transient upward FAC enhancement, which leads to the thin onset arc intensification, would thus be related to the current pair generated in the plasma compression region ahead of the dipolarization front. Thus the earthward penetrating plasma flow channels could play a dominant role in leading to substorm onset.

Xing, X.; Lyons, L. R.; Angelopoulos, V.; Zhou, X.; Donovan, E.; Larson, D. E.; Carlson, C. W.; Auster, U.

2011-12-01

364

Mission to Planet Earth  

International Nuclear Information System (INIS)

Mission to Planet Earth (MTPE) is NASA's concept for an international science program to produce the understanding needed to predict changes in the earth's environment. NASA and its interagency and international partners will place satellites carrying advanced sensors in strategic earth orbits to gather multidisciplinary data. A sophisticated data system will process and archive an unprecedented amount of information about the earth and how it works as a system. Increased understanding of the earth system is a basic human responsibility, a prerequisite to informed management of the planet's resources and to the preservation of the global environment. 8 refs

365

Galactic Cosmic Rays - Clouds Effect and Bifurcation Model of the Earth Global Climate. Part 1. Theory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Based on theoretical and experimental consideration of the first (the Twomey effect) and second indirect aerosol effects the quasianalytic description of physical connection between the galactic cosmic rays intensity and the Earth's cloud cover is obtained. It is shown that the basic equation of the Earth's climate energy-balance model is described by the bifurcation equation (with respect to the temperature of the Earth's surface) in the form of assembly-type catastrophe wi...

Rusov, Vitaliy D.; Glushkov, Alexandr V.; Vaschenko, Vladimir N.; Mykhalus, Oksana T.; Bondartchuk, Yuriy A.; Smolyar, Vladimir P.; Linnik, Elena P.; Mavrodiev, Strachimir Cht; Vachev, Boyko I.

2008-01-01

366

Earth Science Information Center  

Science.gov (United States)

An ESIC? An Earth Science Information Center. Don't spell it. Say it. ESIC. It rhymes with seasick. You can find information in an information center, of course, and you'll find earth science information in an ESIC. That means information about the land that is the Earth, the land that is below the Earth, and in some instances, the space surrounding the Earth. The U.S. Geological Survey (USGS) operates a network of Earth Science Information Centers that sell earth science products and data. There are more than 75 ESIC's. Some are operated by the USGS, but most are in other State or Federal agencies. Each ESIC responds to requests for information received by telephone, letter, or personal visit. Your personal visit.

U.S. Geological Survey

1991-01-01

367

Earth’s Albedo and Global Warming  

Science.gov (United States)

In this interactive activity adapted from NASA and the U.S. Geological Survey, learn about Earth's albedo (the ratio of reflected vs. incident solar radiation), how pollution alters albedo, and how ice-albedo feedback may accelerate global warming.

2008-01-17

368

The right balance  

CERN Multimedia

Over the course of her career as a physicist, Felicitas Pauss, currently responsible for CERN's External Relations, has often been the sole woman in an environment dominated by men. While she freely admits that being a woman physicist can have as many advantages as disadvantages, she thinks the best strategy is to maintain the right balance.   From a very early age, Felicitas Pauss always wanted to be involved in projects that interested and fascinated her. That's how she came to study physics. When she was a first-year university student in Austria in 1970, it was still fairly uncommon for women to go into physics research. "I grew up in Salzburg with a background in music. At that time, it was certainly considered more ‘normal’ for a woman to study music than to do research in physics. But already in high school I was interested in physics and technical instruments and wanted to know how things work and what they are made of”. At the beginning of her care...

CERN Bulletin

2010-01-01

369

Electrodynamics of balanced charges  

CERN Document Server

In this work we modify the wave-corpuscle mechanics for elementary charges introduced by us recently. This modification is designed to better describe electromagnetic (EM) phenomena at atomic scales. It includes a modification of the concept of the classical EM field and a new model for the elementary charge which we call a balanced charge (b-charge). A b-charge does not interact with itself electromagnetically, and every b-charge possesses its own elementary EM field. The EM energy is naturally partitioned as the interaction energy between pairs of different b-charges. We construct EM theory of b-charges (BEM) based on a relativistic Lagrangian with the following properties: (i) b-charges interact only through their elementary EM potentials and fields; (ii) the field equations for the elementary EM fields are exactly the Maxwell equations with proper currents; (iii) a free charge moves uniformly preserving up to the Lorentz contraction its shape; (iv) the Newton equations with the Lorentz forces hold approxi...

Babin, Anatoli

2009-01-01

370

Paul Collier : Balancing beams  

CERN Multimedia

As former head of AB Operations, Paul Collier and his group were in the ‘cockpit’ for the LHC’s maiden voyage - piloting the first beam around the ring. But now, as Head of the Beams Department, he will need his feet firmly on the ground in order to balance all the beam activities at CERN. "As Department Head, I’ll have less direct contact with the machines," Collier says with a hint of regret. "I’ll still obviously be very involved, but they won’t actually let me loose in front of the keyboard anymore!" As the new Head of the BE Department, Collier will be in charge of nearly 400 people, and will oversee all the beam activities, including the preparations for the longest period of beam operation in the history of CERN. In the new organization, the BE, TE and EN Departments have been grouped together in the Accelerator and Technology Sector. "‘Partnership’ is a key word for the three departments," says Collier. "The n...

2009-01-01

371

Balancing "we" and "me".  

Science.gov (United States)

The open office is the dominant form of workspace design for good reason: It fosters collaboration, promotes learning, and nurtures strong culture. But what most companies fail to realize is that collaboration has a natural rhythm that requires both interaction and private contemplation. Companies have been trying for decades to find the balance between public and private workspace that best supports collaboration. In 1980 52% of U.S. employees lacked workspaces where they could concentrate without distraction. In response, high-walled cubicles took over the corporate landscape. By the late 1990s, the tide had turned, and only 23% of employees wanted more privacy, and 50% wanted more access to other people. Ever since, firms have been beefing up spaces that support collaboration and shrinking areas for individual work. But the pendulum seems to have swung too far: Once again, people feel a pressing need for privacy, not only to do heads-down work but to cope with the intensity of work today. To address these needs, according to the authors, we have to rethink our assumptions about privacy. Traditionally defined in physical terms, privacy is now about the individual's ability to control information and stimulation. In this article, the authors examine workspace design through the new lens of privacy and offer insights on how to foster teamwork and solitude. PMID:25509575

Congdon, Christine; Flynn, Donna; Redman, Melanie

2014-10-01

372

Par Pond water balance  

International Nuclear Information System (INIS)

A water budget for the Par Pond hydrologic system was established in order to estimate the rate of groundwater influx to Par Pond. This estimate will be used in modeling exercises to predict Par Pond reservoir elevation and spillway discharge in the scenario where Savannah River water is no longer pumped and discharged into Par Pond. The principal of conservation of mass was used to develop the water budget, where water inflow was set equal to water outflow. Components of the water budget were identified, and the flux associated with each was determined. The water budget was considered balanced when inflow and outflow summed to zero. The results of this study suggest that Par Pond gains water from the groundwater system in the upper reaches of the reservoir, but looses water to the groundwater system near the dam. The rate of flux of groundwater from the water table aquifer into Par Pond was determined to be 13 cfs. The rate of flux from Par Pond to the water table aquifer near the dam was determined to be 7 cfs

373

Structural behaviour of YGa under high pressure  

International Nuclear Information System (INIS)

High pressure X-ray diffraction studies on rare-earth gallide YGa was carried up to a pressure of ? 33 GPa using rotating anode x-ray source in an angle dispersive mode. YGa exhibits CrB (B33) type orthorhombic structure (space group Cmcm) at ambient pressure. It undergoes a reversible structural phase transition from orthorhombic to tetragonal structure at ? 8.8 GPa. Both the phases coexist up to the highest pressure studied. The zero pressure bulk modulus and its derivative for parent phase have been estimated to be Bo = 60 ± 3 GPa, Bo' = 4.6 ± 1.5

374

Structural behaviour of YGa under high pressure  

Energy Technology Data Exchange (ETDEWEB)

High pressure X-ray diffraction studies on rare-earth gallide YGa was carried up to a pressure of ? 33 GPa using rotating anode x-ray source in an angle dispersive mode. YGa exhibits CrB (B33) type orthorhombic structure (space group Cmcm) at ambient pressure. It undergoes a reversible structural phase transition from orthorhombic to tetragonal structure at ? 8.8 GPa. Both the phases coexist up to the highest pressure studied. The zero pressure bulk modulus and its derivative for parent phase have been estimated to be B{sub o} = 60 ± 3 GPa, B{sub o}' = 4.6 ± 1.5.

Sekar, M., E-mail: sekarm@igcar.gov.in; Shekar, N. V. Chandra, E-mail: sekarm@igcar.gov.in; Sahu, P. Ch., E-mail: sekarm@igcar.gov.in [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam- 603 102 Tamil Nadu (India); Babu, R. [Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam- 603 102 Tamil Nadu (India)

2014-04-24

375

Pressure sensor  

International Nuclear Information System (INIS)

The pressure sensor will be used for pressure measurement in high-temperature liquids, in particular for Na or K during fast breeder operation. It has a soft membrane which is unshielded at the pressure medium side and can actuate a rigid membrane an the other side by means of a botton element. The displacement of the rigid membrane is proportional to the difference between the liquid pressure and a reference gas pressure. The displacement can be measured by means of a capacity displacement measuring instrument, using a fixed plate as reference. Absolute calibration is performed by admitting pressurized gas into the zone between the membranes and into the zone between rigid membrane and fixed plate. The coupling between the soft and the rigid membrane is thus interrupted. (DG)

376

Perturbations of a close-earth satellite due to sunlight diffusely reflected from the earth. II - Variable albedo  

Science.gov (United States)

A semianalytical method has been developed to calculate the radiation-pressure perturbations of a close-earth satellite due to sunlight reflected from the earth. It is assumed that the satellite is spherically symmetric and that the solar radiation is reflected from the earth according to Lambert's law. To account for the increasing reflectivity of the earth toward the poles, its albedo is assumed to have a latitudinal dependence. The effect of the terminator on the perturbations has been neglected. The perturbations within a particular revolution are given analytically, while the long-range perturbations are obtained by accumulation.

Lautman, D. A.

1977-01-01

377

Pressure transmitter  

International Nuclear Information System (INIS)

An isolator or the like for nuclear power stations employed to separate two fluids or two pressures or other sensing instruments from the containment or elsewhere includes first and second fluid filled bellows having a fluid connection in between and which together provide a pressure transfer mechanism. Excessive travel of the bellows is prevented by overrange valves, one of which closes the pathway on application of high pressure. (author)

378

Electronic phenomena at high pressure  

International Nuclear Information System (INIS)

High pressure research is undertaken either to investigate intrinsically high pressure phenomena or in order to get a better understanding of the effect of the chemical environment on properties or processes at one atmosphere. Studies of electronic properties which fall in each area are presented. Many molecules and complexes can assume in the excited state different molecular arrangements and intermolecular forces depending on the medium. Their luminescence emission is then very different in a rigid or a fluid medium. With pressure one can vary the viscosity of the medium by a factor of 107 and thus control the distribution and rate of crossing between the excited state conformations. In rare earth chelates the efficiency of 4f-4f emission of the rare earth is controlled by the feeding from the singlet and triplet levels of the organic ligand. These ligand levels can be strongly shifted by pressure. A study of the effect of pressure on the emission efficiency permits one to understand the effect of ligand chemistry at one atmosphere. At high pressure electronic states can be sufficiently perturbed to provide new ground states. In EDA complexes these new ground states exhibit unusual chemical reactivity and new products

379

A new diagram of the global energy balance  

Science.gov (United States)

This study provides a new assessment of the global mean energy flows from a surface perspective as well as an associated diagram of the global mean energy balance. The radiative energy exchanges between Sun, Earth and space are now accurately quantified from new satellite missions. Much less has been known about the magnitude of the energy flows within the climate system and at the Earth surface, which cannot be directly measured by satellites. In addition to satellite observations, the growing number of surface observations is used to constrain the global energy balance not only from space, but also from the surface. These observations are combined with the latest modeling efforts performed for the 5th IPCC assessment report to infer best estimates for the global mean surface radiative components. Our analyses favor global mean downward surface solar and thermal radiation values near 185 and 342 Wm-2, respectively, which are most compatible with surface observations. Combined with an estimated global mean surface absorbed solar radiation and thermal emission of 161 Wm-2 and 398 Wm-2, respectively, this leaves 105 Wm-2 of global mean surface net radiation available for distribution amongst the non-radiative surface energy balance components. Considering an imbalance of 0.6 Wm-2, the global mean sensible and latent heat fluxes are estimated at 20 and 84 Wm-2, respectively, to close the surface energy balance. The global mean surface radiative fluxes derived here in combination with a latent heat flux of 84 Wm-2 may be able to reconcile currently disputed inconsistencies between energy and water cycle estimates. The findings of this study are compiled into a new global energy balance diagram. Related references: Wild, M., Folini, D., Schär, C., Loeb, N., Dutton E.G., and König-Langlo, G., 2013: A new diagram of the global energy balance, AIP Conf. Proc., 1531, 628-631, doi: 10.1063/1.4804848. Wild, M., Folini, D., Schär, C., Loeb, N., Dutton, E.G., and König-Langlo, G., 2013: The global energy balance from a surface perspective, Clim. Dyn., 40, 3107-3134, Doi:10.1007/s00382-012-1569-8. Wild, M., 2012: New Directions: A facelift for the picture of the global energy balance. Atmospheric Environment, 55, 366-367.

Wild, Martin

2014-05-01

380

The Halogen's History of the Early Earth  

Science.gov (United States)

The halogen elements are important in Earth Sciences because, thanks to their unique ability to exist as gazes, liquids and solids, they are perfect tracers and actors for geochemical processes. The cycling of halogens in the Earth is still the matter of controversy because whereas atmosphere, crust and upper mantle are more or less characterized with respect to these elements, a real miss of knowledge is observed concerning the possible role and presence of halogen elements in the deep Earth. In this study we focus on halogen element behaviors during the Earth's differentiation at the Hadean magma ocean stage. We combined synchrotron X-Ray Fluorescence analysis with diamond anvil cells (DAC) experiments at the beam lines Id27 and FAME from ESRF and DiffAbs from SOLEIL. DAC were used as reactors to simulate pressure and temperature conditions relevant for a magma ocean. Experimental monitoring of Br [Bureau et al., 2010, CGA 74, 3839-3850] and I degassing from high pressure hydrous melts was performed in situ in DAC by measuring their partitioning between aqueous fluids and melts during decompression. Results show a stronger affinity of Br and I for the aqueous phase during decompression. Both of them are degassing with water and are totally washout from the melt. Assuming that Br and I are good analogues for F and Cl, and that halogen elements cycle is linked to the Earth's water cycle, this suggests that halogen elements may have been efficiently degassed with water during the early stages of an oxidized magma ocean. We propose that degassing during the Earth's differentiation is one of the first and dominant processes that may have distributed halogen elements between the early Earth's reservoirs.

Bureau, H.; Raepsaet, C.; Munsch, P.; Auzende, A.; Testemale, D.; Mezouar, M.; Kubsky, S.; Carriere, M.; Ricolleau, A.; Fiquet, G.

2012-12-01

 
 
 
 
381

Momentum balances on the inner continental shelf at Martha's Vineyard Coastal Observatory  

Science.gov (United States)

The subtidal, depth-average momentum balances in 12 m and 27 m water depth are investigated using observations from 2001 to 2007 of water velocity, temperature, and density; bottom pressure; surface gravity waves; and wind stress. In the fluctuating across-shelf momentum budget, the dominant terms are surface wind stress, pressure gradient, and Coriolis acceleration. The balance is a combination of (1) the geostrophic balance expected at midshelf sites and (2) the coastal setup and setdown balance driven by the across-shelf wind stress expected where surface and bottom boundary layers overlap. At the 12 m site, the estimated wave radiation stress gradient due to surface gravity wave shoaling is also large but is uncorrelated with the observed pressure gradient. A simple model suggests the wave radiation stress gradient is balanced by an across-shelf pressure gradient with a spatial scale too small to resolve with this mooring array. In the fluctuating along-shelf momentum balance, the dominant terms are surface wind stress, pressure gradient, and bottom stress at the shallower site, but the other estimated terms are not negligible. Our results support the Grant and Madsen (1986) formulation for wave-induced bottom stress. The fluctuating along-shelf pressure gradient is mainly a local sea level response to wind forcing, not a remotely generated pressure gradient. A strong correlation between along-shelf velocity and along-shelf wind stress at the shallower site is captured by a simple steady model of imbalance between wind stress and pressure gradient balanced by linear bottom drag.

Fewings, Melanie R.; Lentz, Steven J.

2010-12-01

382

Thermal balance testing of MSAT 2 spacecraft  

Science.gov (United States)

The present work reports on the recently completed infrared thermal balance/thermal vacuum testing of a MSAT satellite, the first satellite to provide mobile communications service for all of continental North America. MSAT is a two spacecraft program, using a three-axis stabilized Hughes HS-601 series Bus as the vehicle for the Canadian designed Payload. The thermal tests which were performed at the Canadian Space Agency's David Florida Laboratory in Ottawa, Canada, lasted approximately 35 days. The infrared (IR) heating rig was designed to provide radiant heat inputs into seven spacecraft zones during Thermal Vacuum (TV) testing. The TV test was divided into multiple phases. It began with a thermal balance cold phase, followed by a thermal cold cycle and a hot balance phase, complemented by a thermal hot cycle to finish with a thermal cycle with continuous monitoring of the Bus and Payload. The spacecraft's external heat fluxes were provided by IR lamp sources. To ensure flux uniformity, highly reflective baffles and IR East and West faces; the Earth facing (Nadir); and the inside of the thrust cylinder. The aft-end panel heat fluxes were provided by a heated LN2 shroud. The radiation flux intensity on the spacecraft zones from the various rig elements was measured using Monitored Background Radiometers (MBR's) and compared with direct calculations and with pretest predictions. The temperature measurement system was based on Uniform Temperature References (UTR's) located inside the chamber such that all feedthroughs were copper-copper. This system was devised to achieve a temperature measurement accuracy of plus/minus 0.5 C for over 850 thermocouples used in the test. A PC-(QNX-based) based real-time data acquisition system was utilized to provide continuous monitoring of all channels based on a 30-second time scan. In addition, the data acquisition system was able to retrieve telemetry stream from the Satellite Test Equipments (STE) station for real-time data manipulation. Preliminary results showed the test to be successful from both the thermal balance side and the electrical testing side.

Samson, Serge; Choueiry, Elie

1994-11-01

383

Field reversing magnetotail current sheets: earth, Venus, and Comet Giacobini-Zinner  

International Nuclear Information System (INIS)

This dissertation examines the field reversing magnetotail current sheets at the earth, Venus, and Comet Giacobini-Zinner. In the near earth study a new analysis technique is developed to calculate the detailed current density distributions within the cross tail current sheet for the first time. This technique removes the effects of a variable sheet velocity by inverting intersatellite timings between the co-orbiting satellites ISEE-1 and -2. Case studies of three relatively geomagnetically quiet crossings are made; sheet thicknesses and peak current densities are ?1-5 x 104 km and ?5-50 nA/m2. Current density distributions reveal a high density central region, lower density shoulders, and considerable fine structure throughout. In the Venus study another new analysis technique is developed to reconstruct the average tail configuration from a correlation between field magnitude and draping angle in a large statistical data set. In the comet study, high resolution magnetic field and plasma electron data from the ICE traversal of Giacobini-Zinner are combined for the first time to determine the tail/current sheet geometry and calculate certain important but unmeasured local ion and upstream properties. Pressure balance across the tail gives ion temperatures and betas of ?1.2 x 105 K and ?40 in the center of the current sheet to ?1 x 106 K and ?3 in the outer lobes. Axial stress balance shows that the velocity shear upstream near the nucleus is >6 (?1 at ICE), and that a region of strongly enhanced mass loading (ion source rate ?24 times that upstream from lobes) exists upstream from the current sheet. The integrated downtail mass flux is ?2.6 x 1026 H2O+/sec, which is only ?1% of the independently determined total cometary efflux. 79 refs., 37 figs

384

Field reversing magnetotail current sheets: earth, Venus, and Comet Giacobini-Zinner  

Energy Technology Data Exchange (ETDEWEB)

This dissertation examines the field reversing magnetotail current sheets at the earth, Venus, and Comet Giacobini-Zinner. In the near earth study a new analysis technique is developed to calculate the detailed current density distributions within the cross tail current sheet for the first time. This technique removes the effects of a variable sheet velocity by inverting intersatellite timings between the co-orbiting satellites ISEE-1 and -2. Case studies of three relatively geomagnetically quiet crossings are made; sheet thicknesses and peak current densities are approx.1-5 x 10/sup 4/ km and approx.5-50 nA/m/sup 2/. Current density distributions reveal a high density central region, lower density shoulders, and considerable fine structure throughout. In the Venus study another new analysis technique is developed to reconstruct the average tail configuration from a correlation between field magnitude and draping angle in a large statistical data set. In the comet study, high resolution magnetic field and plasma electron data from the ICE traversal of Giacobini-Zinner are combined for the first time to determine the tail/current sheet geometry and calculate certain important but unmeasured local ion and upstream properties. Pressure balance across the tail gives ion temperatures and betas of approx.1.2 x 10/sup 5/ K and approx.40 in the center of the current sheet to approx.1 x 10/sup 6/ K and approx.3 in the outer lobes. Axial stress balance shows that the velocity shear upstream near the nucleus is >6 (approx.1 at ICE), and that a region of strongly enhanced mass loading (ion source rate approx.24 times that upstream from lobes) exists upstream from the current sheet. The integrated downtail mass flux is approx.2.6 x 10/sup 26/ H/sub 2/O+/sec, which is only approx.1% of the independently determined total cometary efflux. 79 refs., 37 figs.

McComas, D.J.

1986-09-01

385

Pressure ulcers  

Science.gov (United States)

Introduction Unrelieved pressure or friction of the skin, particularly over bony prominences, can lead to pressure ulcers in up to one third of people in hospitals or community care, and one fifth of nursing home residents. Pressure ulcers are more likely in people with reduced mobility and poor skin condition, such as older people or those with vascular disease. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of preventive interventions in people at risk of developing pressure ulcers? What are the effects of treatments in people with pressure ulcers? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 64 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: air-filled vinyl boots, air-fluidised supports, alternating-pressure surfaces (including mattresses), alternative foam mattresses, constant low-pressure supports, debridement, electric profiling beds, electrotherapy, hydrocellular heel supports, low-air-loss beds (including hydrotherapy beds), low-level laser therapy, low-tech constant-low-pressure supports, medical sheepskin overlays, nutritional supplements, orthopaedic wool padding, pressure-relieving overlays on operating tables, pressure-relieving surfaces, repositioning (regular "turning"), seat cushions, standard beds, standard care, standard foam mattresses, standard tables, surgery, therapeutic ultrasound, topical lotions and dressings, topical negative pressure, and topical phenytoin. PMID:21524319

2011-01-01

386

Independent effects of adding weight and inertia on balance during quiet standing  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Human balance during quiet standing is influenced by adding mass to the body with a backpack, with symmetrically-applied loads to the trunk, or with obesity. Adding mass to the body increases both the weight and inertia of the body, which theoretically could provide counteracting effects on body dynamics and balance. Understanding the independent effects of adding weight and inertia on balance may provide additional insight into human balance that could lead to novel advancements in balance training and rehabilitation. Therefore, the purpose of this study was to investigate the independent effects of adding weight and inertia on balance during quiet standing. Methods Sixteen normal-weight young adult participants stood as still as possible on a custom-built backboard apparatus under four experimental conditions: baseline, added inertia only, added weight only, and added inertia and weight. Results Adding inertia by itself had no measurable effect on center of pressure movement or backboard movement. Adding weight by itself increased center of pressure movement (indicated greater effort by the postural control system to stand as still as possible and backboard movement (indicating a poorer ability of the body to stand as still as possible. Adding inertia and weight at the same time increased center of pressure movement but did not increase backboard movement compared to the baseline condition. Conclusions Adding inertia and adding weight had different effects on balance. Adding inertia by itself had no effect on balance. Adding weight by itself had a negative effect on balance. When adding inertia and weight at the same time, the added inertia appeared to lessen (but did not eliminate the negative effect of adding weight on balance. These results improve our fundamental understanding of how added mass influences human balance.

Costello Kerry

2012-04-01

387

Thermal History of Planetary Objects: From Asteroids to super-Earths, from plate-tectonics to life (Runcorn-Florensky Medal Lecture)  

Science.gov (United States)

Convection in the interiors of planetesimals (asteroids), planets, and satellites is driving the thermal and chemical evolution of these bodies including the generation of possible magnetic fields. The wide size range induces a wide of range of time scales from hundreds of thousands of years for small planetesimals to a few tens of Gigayears for massive super-Earths. Evolution calculations are often based on energy (and entropy) balances parameterizing the transport properties of the interior in suitable ways. These thereby allow incorporating (in parameterized forms) interesting physical processes that depend in one way or another on the transport properties of the interior. The interior will usually be chemically layered in mantles and cores and include ice layers if icy satellites are considered. In addition to magnetic field generation calculated via energy balances of the core and using semi-empirical dynamo strength relations, processes that can be considered include sintering and compaction for small bodies and mantle (or ice) melting, differentiation and even continental growth for full-scaled terrestrial planets. The rheology of the interior is considered temperature and pressure dependent and the concentration of volatiles can be important. For super-Earths, probably the most critical consideration is how the mantle rheology would vary with pressure and thus with depth. It is possible that the increasing pressure will frustrate deep mantle convection thereby reducing the vigor of mantle convection. Possibly, the generation of a magnetic field in a putative iron-rich core will be impossible, if super-Earths at all have earth-like cores. On a much smaller scale, the decay of short-lived radioactives suffices to heat and melt planetesimals, the melting being helped by the low thermal conductivity of the initially porous body. This allows planets to form from pre-differentiated planetesimals thus helping to differentiate and form cores rapidly. On active planets - like the Earth - the volatile budget matters for the interior evolution. With plate tectonics, large-scale volatile cycles are invoked. On the Earth, even the biosphere is speculated to interact with the interior. It has been argued (e.g., Rosing et al. 2006; Sleep et al, 2012) that the formation of continents could be a consequence of bioactivity harvesting solar energy through photosynthesis to help build the continents and that the mantle should carry a chemical biosignature. A model is presented that includes mantle convection, mantle water vapor degassing at mid-oceanic ridges and regassing through subduction zones, continental crust formation and erosion and water storage and transport in a porous oceanic crust that includes hydrous mineral phases. The biosphere enters the model through its effect on continental erosion and through a reduction of the activation barrier to metamorphic reactions (e.g., Kim et al., 2004) in sediment layers. An abiotic world is found to have a much drier mantle than the present Earth but may have a similar surface coverage by continents. The reduced rate of continental crust production on the abiotic world would be balanced by a reduced rate of continent erosion. Through the effect of water on the mantle rheology, the biotic world would tend to be tectonically more active and have a more rapid long-term carbon-silicate cycle. J. Kim, H. Dong, J. Seabaugh, S. W. Newell, D. D. Eberl, Science 303, 830-832, 2004 N. H. Sleep, D. K. Bird, E. Pope, Annu. Rev. Earth Planet. Sci. 40, 277-300, 2012 M. T. Rosing, D. K. Bird, N. H. Sleep, W. Glassley, F. Albarede, Paleo3 232, 90-113, 2006

Spohn, Tilman

2013-04-01

388

Near Earth Objects  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The word planet comes from Greek planetes, wanderers, because the planets appear to wander across the celestial sphere, contrary to the fixed stars. This thesis presents several methods for using this motion to distinguish between stars and solar system objects in order to detect and track NEOs, Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global ...

Wolff, Stefan

2008-01-01

389

EarthWise Journeys  

Science.gov (United States)

EarthWise Journeys is an independent resource for travel adventures worldwide with special emphasis on socially responsible travel, cross-cultural exchange, and the environment. EarthWise Journeys is dedicated to travelers who seek environmental awareness, adventure, personal growth, and discovery of our global community. EarthWise Journeys assists members find fun and rewarding travel adventures, learning opportunities, volunteer trips with non-profits, and personal retreats. In addition to travel planning, members receive newsletters, the discount airfares ...and more.

390

Simulations of micrometeoroid interactions with the Earth atmosphere  

CERN Document Server

Micrometeoroids (cosmic dust with size between a few $\\mu$m and $\\sim$1 mm) dominate the annual extraterrestrial mass flux to the Earth. We investigate the range of physical processes occurring when micrometeoroids traverse the atmosphere. We compute the time (and altitude) dependent mass loss, energy balance, and dynamics to identify which processes determine their survival for a range of entry conditions. We develop a general numerical model for the micrometeoroid-atmosphere interaction. The equations of motion, energy, and mass balance are simultaneously solved for different entry conditions (e.g. initial radii, incident speeds and angles). Several different physical processes are taken into account in the equation of energy and in the mass balance, in order to understand their relative roles and evolution during the micrometeoroid-atmosphere interaction. In particular, to analyze the micrometeoroid thermal history we include in the energy balance: collisions with atmospheric particles, micrometeoroid radi...

Briani, G; Shore, S N; Pupillo, G; Passaro, A; Aiello, S

2013-01-01

391

Earth's Changing Surface  

Science.gov (United States)

Overview: The Earth's Changing Surface SciPack explores how Earth's ever-changing surface is due to continuous natural processes such as tectonic activity, earthquakes, volcanic activities, weathering and erosion, and sedimentation and the reformation of rock. The focus is on topics supporting Standards and Benchmarks related to how and why these processes occur, and how elements cycle through the land, oceans, and atmosphere as a result of these processes. This SciPack looks at Earth as a system that exists in dynamic equilibrium. In addition to comprehensive inquiry-based learning materials tied to Science Education Standards and Benchmarks, the SciPack includes the following additional components: Pedagogical Implications section addressing common misconceptions, teaching resources and strand maps linking grade band appropriate content to standards. Access to one-on-one support via e-mail to content "Wizards". Final Assessment which can be used to certify mastery of the concepts. Learning Outcomes: Earth's Changing Surface: Changing Earth From Within Explain that both Earth's surface and interior are in motion and describe the causes the motion. Describe how heat within Earth comes from two main sources: radioactive decay and residual heat (gravitational energy left over from the formation of Earth). Explain the fact that the vast majority of earthquakes and volcanic activities which occur near plate boundaries are caused by the movement of the plates. Describe that changes on Earth's surface also happen on the ocean floor to create forms such as ocean basins, mountains and volcanoes. Earth's Changing Surface: Sculpting the Landscape Distinguish between changes in Earth's surface that are abrupt, such as earthquakes and volcanoes and changes that happen very slowly such as uplift and wearing down of mountains. Identify rates of landscape formation. Infer from present data that the processes that shape the earth today are similar to events that occurred in the past. Identify agents of change as destructive, constructive, or both. Describe how erosion by way of waves, wind, glaciers, gravity, running water, etc., causes change in geological features. Earth's Changing Surface: Humans as Agents of Change Distinguish natural processes that shape the surface of Earth from human impact factors that change the surface of Earth. Explain how human activities such as river control, mining, and deforestation have had an effect on the shape of Earth's surface. Describe how human activities do not create new processes but cause changes in the rate and scale of natural processes.

National Science Teachers Association (NSTA)

2008-01-07

392

The Earth: Present Scenario  

Directory of Open Access Journals (Sweden)

Full Text Available In this article, the present scenario of our motherly loved planet ‘Earth’ is presented. We are living in one of the most developed phases of the Earth’s life cycle. The choices we make today will determine the life on the Earth, tomorrow. Problems that are been created by us and the consequences we are going to face are discussed in length. Some statistical data is provided to get a brief idea. Measure/prevention(s to combat the upcoming problems have been putforth.

Nishad Gopal Deshpande

2009-05-01

393

Earth and Moon Viewer  

Science.gov (United States)

At this site you can view either a map of the Earth showing the day and night regions at this moment, or view the Earth from the Sun, the Moon, the night side of the Earth, above any location on the planet specified by latitude, longitude and altitude, from a satellite in Earth orbit, or above various cities around the globe. Images can be generated based on a full-colour image of the Earth by day and night, a topographical map of the Earth, up-to-date weather satellite imagery, or a composite image of cloud cover superimposed on a map of the Earth, or a color composite which shows clouds, land and sea temperatures, and ice. In addition to the Earth, you can also view the Moon from the Earth, Sun, night side, above named formations on the lunar surface or as a map showing day and night. A related document compares the appearance of the Moon at perigee and apogee, including an interactive Perigee and Apogee Calculator.

Walker, John

1999-03-27

394

Stability of xenon oxides at high pressures.  

Science.gov (United States)

Xenon, which is quite inert under ambient conditions, may become reactive under pressure. The possibility of the formation of stable xenon oxides and silicates in the interior of the Earth could explain the atmospheric missing xenon paradox. Using an ab initio evolutionary algorithm, we predict the existence of thermodynamically stable Xe-O compounds at high pressures (XeO, XeO(2) and XeO(3) become stable at pressures above 83, 102 and 114 GPa, respectively). Our calculations indicate large charge transfer in these oxides, suggesting that large electronegativity difference and high pressure are the key factors favouring the formation of xenon compounds. However, xenon compounds cannot exist in the Earth's mantle: xenon oxides are unstable in equilibrium with the metallic iron occurring in the lower mantle, and xenon silicates are predicted to decompose spontaneously at all mantle pressures (possible that xenon atoms may be retained at defects in mantle silicates and oxides. PMID:23247179

Zhu, Qiang; Jung, Daniel Y; Oganov, Artem R; Glass, Colin W; Gatti, Carlo; Lyakhov, Andriy O

2013-01-01

395

Aging: Balancing regeneration and cancer  

Energy Technology Data Exchange (ETDEWEB)

The proliferation of cells must balance the longevity assured by tissue renewal against the risk of developing cancer. The tumor-suppressor protein p16{sup INK4a} seems to act at the pivot of this delicate equilibrium.

Beausejour, Christian M.; Campisi, Judith

2006-08-24

396

Are Social Networks Really Balanced?  

CERN Document Server

There is a long-standing belief that in social networks with simultaneous friendly/hostile interactions (signed networks) there is a general tendency to a global balance. Balance represents a state of the network with lack of contentious situations. Here we introduce a method to quantify the degree of balance of any signed (social) network. It accounts for the contribution of all signed cycles in the network and gives, in agreement with empirical evidences, more weight to the shorter than to the longer cycles. We found that, contrary to what is believed, many signed social networks -- in particular very large directed online social networks -- are in general very poorly balanced. We also show that unbalanced states can be changed by tuning the weights of the social interactions among the agents in the network.

Estrada, Ernesto

2014-01-01

397

How Our Balance System Works  

Science.gov (United States)

... impulses to the brain by way of the acoustic nerve. The nerve impulses are processed in the brain ... as nystagmus) Complaints of vertigo or dizziness Balance dysfunction Gait abnormalities Suspected pathology or disease of the ...

398

Electric power balance sheet 2012  

International Nuclear Information System (INIS)

The mission of RTE, the French electricity Transportation grid, a public service assignment, is to balance the electricity supply and demand in real time. This report presents RTE's technical results for the year 2012: strong seasonal contrast of power consumption, rise of the renewable energies contribution in meeting the electricity demand, slight decay of the nuclear and thermal power generation, decrease of the export balance and change in trades structure, adaptation of RTE's network to the evolutions of the energy system

399

Ankylosing Spondylitis and Postural Balance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objective: In this study, we aimed to investigate that, due to postural changes, the patients with ankylosing spondyilitis (AS) have poorer postural balance than healthy subjects.Materials and Methods: Thirty patients with AS (19 female, 11 male) and 20 healthy subjects (13 female, 7 male) were tested by using the Tetrax Interactive Balance System. The general stability, Fourier analysis showing patterns of sway intensity within eight frequency bands between 0.1 and 3 Hz, and weight distribut...

Mahmut Nafiz Akman; Selda Bagis; Alper Nabi Erkan; Berrin Leblebici; Mehmet Adam

2008-01-01

400

Form 6 - gas balancing agreement  

International Nuclear Information System (INIS)

In 1988, a special Committee of the Rocky Mountain Mineral Law Foundation undertook a project to draft a model from gas balancing agreement. This project was initiated at the request of a number of Foundation members who felt that a model form gas balancing agreement would facilitate the negotiation of operating agreement, since gas balancing issues had become sticking points in the process. The Committee was composed of attorneys representing a wide cross-section of the oil and gas industry including both major and independent oil companies, production companies with interstate pipeline affiliates, and private practitioners. The Committee attempted to address the more controversial issues in gas balancing with optional provisions in the Form. To facilitate the negotiation process, the number of optional provisions was minimized. This form may be used as an Appendix to the new A.A.P.L. Form 610-1989 Model Form Operating Agreement. This book includes provision of this Form which are: Ownership of gas production; Balancing of production accounts; Cash balancing upon depletion; Deliverability tests; Nominations; Statements; Payment of taxes; Operating expenses; Overproducing allowable; Payment of leasehold burdens; Operator's liability; Successors and assigns; Audits; Arbitration; and Operator's fees

 
 
 
 
401

Pressure correction schemes for compressible flows  

International Nuclear Information System (INIS)

This thesis is concerned with the development of semi-implicit fractional step schemes, for the compressible Navier-Stokes equations; these schemes are part of the class of the pressure correction methods. The chosen spatial discretization is staggered: non conforming mixed finite elements (Crouzeix-Raviart or Rannacher-Turek) or the classic MA C scheme. An upwind finite volume discretization of the mass balance guarantees the positivity of the density. The positivity of the internal energy is obtained by discretizing the internal energy balance by an upwind finite volume scheme and b y coupling the discrete internal energy balance with the pressure correction step. A special finite volume discretization on dual cells is performed for the convection term in the momentum balance equation, and a renormalisation step for the pressure is added to the algorithm; this ensures the control in time of the integral of the total energy over the domain. All these a priori estimates imply the existence of a discrete solution by a topological degree argument. The application of this scheme to Euler equations raises an additional difficulty. Indeed, obtaining correct shocks requires the scheme to be consistent with the total energy balance, property which we obtain as follows. First of all, a local discrete kinetic energy balance is established; it contains source terms winch we somehow compensate in the internal energy balance. The kinetic and internal energy equations are associated with the dual and primal meshes respectively, and thus cannot be added to obtain a total energy balance; its continuous counterpart is however recovered at the limit: if we suppose that a sequence of discrete solutions converges when the space and time steps tend to 0, we indeed show, in 1D at least, that the limit satisfies a weak form of the equation. These theoretical results are comforted by numerical tests. Similar results are obtained for the baro-tropic Navier-Stokes equations. (author)

402

Capturing near-Earth asteroids around Earth  

Science.gov (United States)

The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the numerically calculated trajectories, 23 asteroids are recommended for future consideration for capture missions, provided necessary technological developments are made.

Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

2012-12-01

403

Rare earth substituted 124 and 247 superconductors  

Energy Technology Data Exchange (ETDEWEB)

Rare earth substitution has given a series of superconducting compounds in which Tc can be correlated with lattice parameters. Eight rare earth compounds with 124 structure, and five with 247 structure, are easily synthesized in oxygen at pressures between 10 and 70 bar. The 247 compounds are stable only within a narrow range of oxygen pressures bounded by the stability regions of the 124 and 123 phases. The Tc's of the 124 and 247 phases vary inversely with ion size. Surprisingly, the 247 compounds have much lower Tc's (45-55 K) than the 124 or 123 parent compounds. The basal plane areas of 247 are larger and orthorhombic distortions smaller than the corresponding 123 and 124, suggesting weaker bonding in the CuO{sub 2} layers. (orig.).

Morris, D.E.; Asmar, N.G.; Wei, J.Y.T.; Sid, R.L.; Nickel, J.H.; Scott, J.S. (Lawrence Berkeley Lab., CA (USA)); Post, J.E. (Smithsonian Inst., National Museum of Natural History, Washington, DC (USA))

1989-12-01

404

Rare earth substituted 124 and 127 superconductors  

International Nuclear Information System (INIS)

This paper reports how rare earth substitution has given a series of superconducting compounds in which Tc can be correlated with lattice parameters. Eight rare earth compounds with 124 structure, and five with 247 structure, are easily synthesized in oxygen at pressures between 10 and 70 bar. The 247 compounds are stable only within a narrow range of oxygen pressures bounded by the stability regions of the 124 and 123 phases. The Tcs of the 124 and 247 phases vary inversely with ion size. Surprisingly, the 247 compounds have much lower Tcs (45-55 K) than the 124 or 123 parent compounds. The basal plane areas of 247 are larger and orthorhombic distortions smaller than the corresponding 123 and 124, suggesting weaker bonding in the CuO2 layers

405

Análise de fases por difração de raios X de WC-10%Co dopado com terras-raras obtido sob alta pressão / Phase analysis by x-ray diffraction on the WC-10Co doped with rare-earth elements obtained under high pressure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O carbeto cementado WC-Co também denominado de metal duro é um material de grande importância tecnológica produzido por metalurgia do pó através de sinterização por fase líquida, partindo-se da mistura dos pós de carbeto de tungstênio (WC) e de cobalto (Co) em moinho convencional. Entretanto, para o [...] btenção de metal duro com maior capacidade (produtividade, vida útil, etc.), uma nova rota alternativa de metalurgia do pó denominada de altas pressões e altas temperaturas vem sendo utilizada para produção destes materiais com resultados promissores. O presente trabalho tem como objetivo principal a análise de fases de WC-10Co dopado com terras-raras (La2O3, CeO2e Y2O3) preparadas sob condições de alta pressão. Esta liga de metal duro é um exemplo de material compósito largamente utilizado como ferramenta de corte e operações de usinagem em geral. Foram preparadas diversas misturas de WC-10Co contendo até 2 % em peso de terra-rara (La2O3, CeO2e Y2O3) da fase cobalto. Os pós previamente misturados foram compactados numa matriz cilíndrica (? = 7 mm) a uma pressão de 800 MPa e sinterizados a 1400 ºC durante 40 s sob alta pressão de 5,5 GPa. Os compósitos produzidos foram caracterizados por difração de raios X para identificação de fases cristalinas presentes. Além disso, foi feita análise comparativa entre o carbeto isento de terra-rara (amostras de referência) e carbetos dopados com elementos de terra-rara (La2O3, CeO2, e Y2O3). Para as condições estudadas os resultados mostraram que durante o processo de sinterização ocorreu à formação, mesmo que em pequenas quantidades, das fases Co3W3C2 e ? (carbeto tipo ?) nas peças de metal duro estudadas. Abstract in english The WC-Co cemented carbide also called hardmetal is a material of great technological importance, currently produced by powder metallurgy by liquid phase sintering, starting from the mixture of powdered tungsten carbide (WC) and cobalt (Co) using conventional mill. Seeking to obtain materials with h [...] igher capacity (productivity, life, etc