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1

Balanced Earth satellite orbits  

Science.gov (United States)

An analytic model for third-body perturbations and for the second zonal harmonic of the central body's gravitational field is presented. A simplified version of this model applied to the Earth-Moon-Sun system indicates the existence of high-altitude and highly-inclined orbits with their apsides in the equator plane, for which the apsidal as well as the nodal motion ceases. For special positions of the node, secular changes of eccentricity and inclination disappear too ('balanced' orbits). For an ascending node at vernal equinox, the inclination of balanced orbits is 94.56 deg, for a node at autumnal equinox 85.44 deg, independent of the eccentricity of the orbit. For a node perpendicular to the equinox, there exist circular balanced orbits at 90 deg inclination. By slightly adjusting the initial inclination as suggested by the simplified model, orbits can be found - calculated by the full model or by different methods - that show only minor variations in eccentricity, inclination, argument of perigee, and longitude of the ascending node for 105 revolutions and more. Orbits near the unstable equilibria at 94.56 deg and 85.44 deg inclination show very long periodic librations and oscillations between retrogade and prograde motion.

Kudielka, V.

1994-12-01

2

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.

3

Recent Energy Balance of Earth  

Directory of Open Access Journals (Sweden)

Full Text Available A recently published estimate of Earth’s global warming trend is 0.63 ± 0.28 W/m2, as calculated from ocean heat content anomaly data spanning 1993-2008. This value is not representative of the recent (2003-2008 warming/cooling rate because of a “flattening” that occurred around 2001-2002. Using only 2003-2008 data from Argo floats, we find by four different algorithms that the recent trend ranges from –0.010 to –0.161 W/m2 with a typical error bar of ±0.2 W/m2. These results fail to support the existence of a frequently-cited large positive computed radiative imbalance.

Robert S. Knox

2010-11-01

4

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 be observed, say 1400 km. (orig.)

5

Earth radiation pressure effects on satellites  

Science.gov (United States)

A diffuse-earth radiation force model is presented, which includes a latitudinally varying representation of the shortwave and longwave radiation of the terrestrial sphere. Applications to various earth satellites indicate that this force, in particular the shortwave component, can materially affect the recovery of estimated parameters. Earth radiation pressure cannot explain the anomalous deceleration of LAGEOS, but can produce significant along track accelerations on satellites with highly eccentric orbits. Analyses of GEOS-1 tracking data confirm this result.

Knocke, P. C.; Ries, J. C.; Tapley, B. D.

1988-01-01

6

Global Sea Level Rise and the Earth's Energy Balance  

Science.gov (United States)

As the oceans warm due to human-caused climate change, they contribute to both global and regional sea level rise. But the uptake of heat by the ocean also reflects the net radiative imbalance of the planet due to human interference with the climate. Global sea level rise and its components therefore provide a constraint on the Earth's Energy Balance, and vice versa. We will present an assessment of the sea level and energy budgets and their implications for the magnitude of deep ocean warming and net radiative forcing over the past decade. Observations from satellite altimeters and the GRACE gravity mission will be compared with in situ observations of ocean warming. In addition, we will consider observations from the Clouds and the Earth's Radiant Energy System (CERES) instruments to assess the Earth's net radiation balance. Finally, a new estimate of bias corrections for the XBT observations will be assessed and presented.

Willis, J.; Hobbs, W. R.

2012-12-01

7

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

8

Modeling of the Earth’s Planetary Heat Balance with Electrical Circuit Analogy  

Directory of Open Access Journals (Sweden)

Full Text Available The integral heat model for the system of the Earth’s surface—the atmosphere—the open space based on the electrical circuit analogy is presented. Mathematical models of the heat balance for this system are proposed. Heat circuit which is analog of the electrical circuit for investigating the temperature dependencies on the key parameters in the clear form is presented.

Yevgeniy V. Lapovok

2010-04-01

9

An observationally based energy balance for the Earth since 1950  

Science.gov (United States)

Perturbations to the Earth’s energy balance since 1950 are examined using measurements and radiative transfer calculations, thus identifying results that can be obtained without using global climate models. Important terms that can be constrained in this way are ocean heat content, radiative forcing by long-lived trace gases, radiative forcing from volcanic eruptions, and the increasing emission of heat from a warming Earth. We explicitly consider the emission of energy by a warming Earth by using correlations between surface temperature and satellite radiant flux data to define this term and show that is already quite significant. About 20% of the integrated positive forcing by greenhouse gases and solar radiation since 1950 has been radiated to space. Only about 10% of the positive forcing (about 1/3 of the net forcing) has gone into heating the Earth, almost all into the oceans. About 20% of the positive forcing has been balanced by volcanic aerosols and the remaining 50% is mainly attributable to tropospheric aerosols. After accounting for the measured terms, the residual forcing between 1970 and 2000 due to direct and indirect forcing by aerosols as well as semidirect forcing from greenhouse gases and any unknown mechanism can be estimated as -1.1±0.4 W m-2 (1 sigma). This is consistent with IPCC best estimates but rules out very large negative forcings from aerosol indirect effects. Further, the data imply an increase from the 1950s to the 1980s followed by constant or slightly declining aerosol forcing into the 1990s, consistent with estimates of trends in global sulfate emissions. An apparent increase in residual forcing in the late 1990s may be due to inconsistencies in the ocean heat uptake data.

Murphy, D. M.; Solomon, S.; Portmann, R. W.; Rosenlof, K. H.; Forster, P.; Wong, T.

2009-12-01

10

Pressure balanced drag turbine mass flow meter  

Science.gov (United States)

The density of the fluid flowing through a tubular member may be measured by a device comprising a rotor assembly suspended within the tubular member, a fluid bearing medium for the rotor assembly shaft, independent fluid flow lines to each bearing chamber, and a scheme for detection of any difference between the upstream and downstream bearing fluid pressures. The rotor assembly reacts to fluid flow both by rotation and axial displacement; therefore concurrent measurements may be made of the velocity of blade rotation and also bearing pressure changes, where the pressure changes may be equated to the fluid momentum flux imparted to the rotor blades. From these parameters the flow velocity and density of the fluid may be deduced.

Dacus, M.W.; Cole, J.H.

1980-04-23

11

Why is the earth not burning ? The earth radiative energy balance  

CERN Document Server

The concept of energy balance is a key one in climate science. Yet, students may find it counterintuitive: while it is obvious that some energy comes in from the sun, the part coming out is more elusive. Asking them why the earth is not burning after billions of years of exposure to the sun, takes them to the question "where does the energy goes?" A series of Fermi like calculations then convinces them that storage capabilities are negligible compared to the amount of energy coming in: the earth necessarily re-emits what it receives.

Bret, A

2011-01-01

12

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)

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

Journey to the Center of the Earth: Exploring High Pressure  

Energy Technology Data Exchange (ETDEWEB)

The deeper we go into the Earth, the higher the pressure. At the pressures found within the center of our planet, minerals do not simply compress. Pressure dramatically alters all materials properties, in the process creating numerous novel phases not found on the surface. This lecture will describe how we simulate the conditions found in planetary interiors in the lab, what kinds of new behavior we find, and how these observations can explain what is going on within the Earth. High pressure explorations also lead to discoveries of novel materials with potential for practical applications in our low-pressure, environment.

Mao, Wendy

2009-09-29

15

Analytical study of pressure balancing in gas film seals  

Science.gov (United States)

The load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

Zuk, J.

1973-01-01

16

A Balanced-pressure Sliding Seal for Transfer of Pressurized Air Between Stationary and Rotating Parts  

Science.gov (United States)

A combination sliding-ring and pressure-balancing seal capable of transferring pressurize air from stationary to rotating parts was developed and experimentally investigated at sliding velocities and cooling-air pressures up to 10,000 feet per minute and 38.3 pounds per square inch absolute, respectively. Leakage of cooling air was completely eliminated with an expenditure of balance air less than one-fourth the leakage loss of air from labyrinth seals under the same conditions. Additional cooling of the carbon-base seal rings was required, and the maximum wear rate on the rings was about 0.0005 inch per hour.

Curren, Arthur N; Cochran, Reeves P

1957-01-01

17

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

18

Molecular atmospheric transmittance function in the range of 2-400 ?m and Earth radiation balance.  

Science.gov (United States)

Mechanisms of the influence of the atmospheric transmission function, in the range 2-400 ?m and especially in the windows 8-13 and 3-4 ?m, on the thermal balance of the Earth's atmosphere are discussed. The negative and positive feedbacks between the absorption of the outgoing heat radiation in the atmosphere and the heating of the Earth's surface are considered. The database GEISA-92, which provides spectral line parameters of atmospheric constituents, has been used for simulations of infrared radiation transfer and the Earth's radiation balance. The temperature dependence of the molecular transmission function is calculated, and three steady states for Earth radiation balance are obtained. A type of the radiation balance, leading to "closing" of the atmospheric transmittance window 8-13 ?m and development of the explosive greenhouse effect, is discussed.

Zakharov, V. I.; Gribanov, K. G.; Falko, M. V.; Golovko, V. F.; Chursin, A. A.; Nikitin, A. V.; Tyuterev, V. G.

1997-01-01

19

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

20

Economics as if the earth really mattered. Putting balance back on the balance sheet.  

Science.gov (United States)

Some of the thinking in the economic realm which affects the relationship between the economy and the environment is discussed. The standard economic model inherently conflicts with the environment. Humans as consumers have their needs met by maximizing production and efficiency in a free market economy, where an invisible hand guides to profit. The question is raised as to what the environmental impact is for economic growth. The need for clean air, water, and preservation of other living things is not met. It is argued that pollution is a necessary byproduct of production. Economic progress as measured by gross national product (GNP) cannot account for the degradation of nature, e.g., the Alaskan oil spill actually increased GNP. Traditional economics also tell little about the maldistribution of wealth. It is pointed out that Americans spend $5 billion a year on special diets while 400 million around the world are undernourished. Limits to natural resources are also not accounted for by economic theorists, or the value of the seemingly free life-sustaining services performed by a forest in purifying air, preventing erosion and flooding, regulating climate, and supporting biological diversity. It is pointed out that restructuring must occur if the capacity of the Earth to support life is classed in economic terms as an externality. Steady state economic models consider the cycles of production and consumption in the context of the surrounding ecosystem of waste and raw materials and try to achieve a state of equilibrium. Despite the 1972 President's Commission on Population Growth and the American Future's statement that population growth is not necessary for a vital economy, the mythology exists that the economy will collapse, personal income will drop, and business will decline without an ever-growing population. A summary on positive outcomes of zero population growth is given. The economist Julian Simon promotes the view that there is no environmental degradation and technological fixes and human ingenuity will keep prosperity growing. Economic growth is seen as the cure for poverty, unemployment, and other ills. Technology has its shortcomings as pesticides and soil depletion have shown. Food supplies have dropped. Sustainability with all its lack of specificity has come to mean more rapid economic growth in both developed and developing countries, with assumptions of an infinite universe and economic expansion. A steady state economy aims to reduce overconsumption and stop population growth in order to balance the economic system in the ecosystem. PMID:12284468

Sherman, D

1991-09-01

 
 
 
 
21

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)

22

High pressure ?SR studies: rare earths and related materials  

International Nuclear Information System (INIS)

After a short introduction to ?SR with respect to the study of magnetic properties, followed by a brief outline of the principle of the high pressure-low temperature ?SR spectrometer installed at the Paul Scherrer Institute, we discuss some measurements on rare earth materials employing this instrument. They are concerned with: (1) The pressure dependence of the spin turning process in ferromagnetic Gd. (2) The volume dependence of the internal magnetic field in the heavy rare earth metals Gd, Dy, and Ho in their ordered magnetic states. (3) The response of the (first order) magnetic transition in the frustrated antiferromagnets of type RMn2 (R = Y,Gd) to pressure. (4) The variation of magnetic parameters with pressure in La2CuO4 (powder sample), the antiferromagnetic parent compound of the high TC superconductors of type La2-x(Sr, Ba)xCuO4. In conclusion a short outlook on further developments is given

23

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

24

Performance of earth pressure cell as grain pressure transducer in a model silo  

Directory of Open Access Journals (Sweden)

Full Text Available Numerous methods have been proposed for determining the pressure exerted by grain at discrete locations in a storage structure, but few satisfactory solutions have been found. Earth pressure cells were tested as potential measurement devices for grain bins. Earth pressure cells are commercial transducers designed for geotechnical applications. Calibration of the earth pressure cell was performed in a pressurized chamber filled with wheat under normal load as well as shear load. The cell was tested in a model grain silo 1.83 m in diameter d with a height hc of 5.75 m. Vertical floor pressures and horizontal wall pressures were measured at different points in the model bin. The vertical floor pressure pvi was measured at two different radial locations and horizontal wall pressure ph was measured at four different wall heights. The vertical floor pressure obtained using the earth pressure cell was in good agreement with the mean floor pressure pv calculated using load cells that supported the entire floor or the bin. Considerable variation in the vertical floor pressure along the silo floor radius was observed. The variation of the lateral-to-vertical pressure ratio, K, was monitored during each fill-unload cycle of the model silo. In the case of the maximum h/d ratio of 2, K increased during filling and stabilized after reaching a grain h/d ratio of 1.3. At the onset of discharge, the pressure ratio immediately increased up to value of approximately 0.7, and remained stable during unloading down to a h/d ratio of approximately 0.65 when K decreased rapidly.

J. Horabik

2007-03-01

25

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

26

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.

27

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

28

Water-Energy balance in pressure irrigation systems  

Science.gov (United States)

Modernization of irrigation schemes, generally understood as transformation of surface irrigation systems into pressure -sprinkler and trickle- irrigation systems, aims at, among others, improving irrigation efficiency and reduction of operation and maintenance efforts made by the irrigators. Automation techniques become easier after modernization, and operation management plays an important role in energy efficiency issues. Modern systems use to include elevated water reservoirs with enough capacity to irrigate during peak water demand period about 16 to 48 h. However, pressure irrigation systems, in contrast, carry a serious energy cost. Energy requirements depend on decisions taken on management strategies during the operation phase, which are conditioned by previous decisions taken on the design project of the different elements which compose the irrigation system. Most of the countries where irrigation activity is significant bear in mind that modernization irrigation must play a key role in the agricultural infrastructure policies. The objective of this study is to characterize and estimate the mean and variation of the energy consumed by common types of irrigation systems according to their management possibilities. Also is an objective to estimate the fraction of the water reservoirs available along the irrigation campaign for storing the energy from renewable sources during their availability periods. Simulation taking into account all elements comprising the irrigation system has been used to estimate the energy requirements of typical irrigation systems of several crop production systems. The simulation of various types of irrigation systems and management strategies, in the framework imposed by particular cropping systems, would help to develop criteria for improving the energy balance in relation to the irrigation water supply productivity and new opportunities in the renewable energy field.

Sánchez, Raúl; Rodríguez-Sinobas, Leonor; Juana, Luis; Laguna, Francisco V.; Castañón, Guillermo; Gil, María; Benitez, Javier

2013-04-01

29

STOCHASTIC ACCELERATION OF SUPRATHERMAL PARTICLES UNDER PRESSURE BALANCE CONDITIONS  

International Nuclear Information System (INIS)

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?p –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 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 pI . 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?p –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.

30

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

31

How reliable are latitudinal energy balance models for habitability calculations when using Earth's radiative properties?  

Science.gov (United States)

Exoplanet habitability studies are often performed using simple energy balance models (EBMs), which rely on an understanding of a planet's radiative properties. However, knowledge of these properties is currently limited. Here, I use Earth as a testbed for examining habitability and model uncertainty in a diffusive latitudinal EBM. Using an empirical approach, I parametrize Earth's radiative properties - top of atmosphere albedo and outgoing infrared radiation - as a function of surface temperature, using measurements from the NASA Clouds and Earth's Radiant Energy System instruments. When using surface temperature to construct these functions, a bias analysis shows only small global biases of 3 and - 0.3 W m-2 are introduced for the albedo and infrared functions, respectively. I also show there is a very fine balance between Earth's incoming solar and outgoing infrared radiation in the observational data, which is substantially smaller than previously assumed in this model. Using observationally derived radiative functions for an Earth-like planet, the snowball transition can be determined within a semimajor axis of ˜3 per cent, with a structural uncertainty of ˜2 per cent in the radiative function construction. This work shows that diffusive EBMs can be successfully used to identify habitable exo-Earths within ˜3 per cent if the radiative properties are known.

Gilmore, James B.

2014-05-01

32

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 (R(3+)) 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 (R(2+)) 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 R(2+) ? R(3+) 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. PMID:24934628

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

2014-07-01

33

Measurement of the earth radiation balance as an instrument design problem.  

Science.gov (United States)

The net radiation balance of the earth is important globally for synoptic scale models and long-term climatic trends. It is important at the mesoscale level because it is a strong driving force on local meteorological phenomena. Both synoptic and mesoscale measurements are possible only from earth orbiting spacecraft, and serious efforts have been made to implement them. They have not achieved sufficient accuracy, precision, and stability to be really meaningful meteorologically. Measuring a small difference between two large numbers-the input to the earth and the earth radiation to space-is quite difficult and compounded by the spectral differences between the two. The instrumental considerations to achieving improvements in net radiation balance are discussed. The ratio of input to outflow, like albedo, is a dimensionless number which is amenable to measurement without recourse to calibrated instruments. If the solar constant is indeed reasonably constant, this ratio, which is more easily measured than an absolute value of either quantity, will be acceptable. Instrument stability, both spectral and absolute, as well as calibration methods and accuracy will be discussed with specific emphasis on estimating how and to what degree they can be improved. PMID:20168484

Yates, H W

1977-02-01

34

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

35

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.

36

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)

37

Pressure regimes and core formation in the accreting earth  

Science.gov (United States)

Recent work suggests that a large degree of melting is required to segregate metal from silicates, suggesting a connection with the formation of magma oceans. At low pressures metallic liquids do not wet silicate minerals, preventing the metal from aggregating into large masses that can sink. At high pressures, above 25 GPa, the dihedral angles of grains in contact with oxygen-rich metallic liquids may be reduced enough to allow percolation of metal, but this has not been confirmed. Physical models of core formation and accretion may therefore involve the formation of magma oceans and the segregation of metal at both high and low pressures. Models of core formation involving different pressure regimes are discussed as well as chemical evidence bearing on the models. Available geophysical data is ambiguous. The nature of the 670 km boundary (chemical difference or strictly phase change) between the upper and lower mantle is in doubt. There is some evidence that plumes are derived from the lower mantle, and seismic tomography strongly indicates that penetration of subducting oceanic crust into the lower mantle, but the tomography data also indicates that the 670 km discontinuity is a significant barrier to general mantle convection. The presence of the D' layer at the base of the lower mantle could be a reaction zone between the mantle and core indicating core-mantle disequilibrium, or D' layer could be subducted material. The abundance of the siderophile elements in the mantle could provide clues to the importance of high pressure processes in Earth, but partition coefficients at high pressures are only beginning to be measured.

Newsom, H. E.

1992-01-01

38

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

39

Effects of the O-ring used for sealing in high-pressure balances on measurements of pressure  

Science.gov (United States)

An oil-operated pressure balance is standard equipment widely used in the field of pressure metrology. Most of the commonly used pressure balances are in a simple piston-cylinder configuration where the piston and the cylinder can deform freely under pressure. This simple piston-cylinder assembly has an O-ring chamber on the cylinder bottom to seal the cylinder. The effects of this O-ring seal on the effective area are not well known. This paper demonstrates by the numerical method using finite element method and the experimental method that, when performing precise measurements of pressure using a pressure balance, the cylinder will be deformed by the oil pressure exerted on the bottom of the cylinder surrounded by the O-ring, causing a non-linearity in the change of effective area, and that, when the piston-cylinder assembly is used in the body with different diameters of O-ring, the effective area, i.e. the pressure, can be significantly changed. The effects of O-ring seals on the effective area of a DH5306 oil-operated pressure balance were investigated using two piston-cylinder assemblies with nominal effective areas of 2 mm2 over the pressure range of 100-300 MPa. Three different sizes of O-ring, 4.8, 8.0 and 11.7 mm in diameter, were used. The maximum change of the effective area can reach 30 ppm at 300 MPa and 18 ppm at 100 MPa due to the change of O-ring. Therefore, for precise pressure measurement, the correct understanding of the O-ring under the cylinder is required along with checking of the size of the O-ring under the cylinder whenever calibrating the piston-cylinder assembly.

Woo, S. Y.; Lee, Y. J.; Choi, I. M.; Kim, B. S.; Shin, H. H.

2002-08-01

40

Pressure balance between midplane and inner and outer divertor in ASDEX Upgrade H-mode discharges  

Energy Technology Data Exchange (ETDEWEB)

Electron pressure profiles have been obtained in the outer midplane and along the divertor target using various diagnostics in ASDEX Upgrade. Inter-ELM and ELM phases of H-mode discharges with different power- and neutral fluxes in the divertor are investigated. To check the parallel pressure balance, mapping using equilibrium reconstruction is corrected/checked by physics constraints, like the upstream separatrix temperature according to power balance. Good agreement between the midplane pressure and the divertor pressure obtained from Langmuir probe measurements, assuming a Mach flow = 1 into the sheath, is observed for the outer scrape-off layer (SOL). A pressure reduction around the strike point by more than one order of magnitude is observed for low power, high neutral flux conditions. Strong detachment/pressure loss is seen in the inner divertor for all conditions. During ELMs, higher electron pressures are obtained in the outer divertor SOL compared to the midplane.

Kallenbach, A. [Max-Planck-Institut fuer Plasmaphysik, IPP-EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)], E-mail: Arne.Kallenbach@ipp.mpg.de; Dux, R.; Eich, T.; Fischer, R.; Herrmann, A.; Kurzan, B.; Mueller, H.W.; Neu, R.; Pugno, R.; Wischmeier, M.; Wolfrum, E. [Max-Planck-Institut fuer Plasmaphysik, IPP-EURATOM Association, Boltzmannstr. 2, D-85748 Garching (Germany)

2009-06-15

 
 
 
 
41

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

42

The Earth's radiation balance and its representation in CMIP5 models  

Science.gov (United States)

The genesis and evolution of Earth's climate is largely regulated by the global energy balance. Despite the central importance of the global energy balance for the climate system and climate change, substantial uncertainties still exist in the quantification of its different components, and its representation in climate models. While the net radiative energy flow in and out of the climate system at the top of atmosphere is known with considerable accuracy from new satellite programs such as CERES, much less is known about the energy distribution within the climate system and at the Earth surface. Accordingly, the quantification of the global energy balance has been controversially disputed in the past. Here we review this discussion and make an attempt to put additional constraints on the components with largest uncertainties. In addition to satellite observations, we thereby make extensive use of the growing number of surface observations to constrain the global energy balance not only from space, but also from the surface. We combine these observations with the latest modeling efforts performed for the 5th IPCC assessment report (CMIP5) 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. These estimates are lower and higher, respectively, than in many previous assessments, including those presented in previous IPCC reports. It is encouraging that our estimates, which make full use of the information contained in the surface networks, coincide within 2 Wm-2 with the latest satellite-derived estimates (Stephens et al. 2012, Kato et al. submitted to J. Climate), which are completely independently determined. Combining our above estimates with an estimated global mean surface absorbed solar radiation and thermal emission of 161 Wm-2 and 397 Wm-2, respectively, results in 106 Wm-2 of surface net radiation globally available for distribution amongst the non-radiative surface energy balance components. The 23 CMIP5 models investigated in this study overestimate the downward solar and underestimate the downward thermal radiation, both by 5-10 Wm-2 on average. Thus, the CMIP5 models nevertheless simulate an adequate global mean surface net radiation, by error compensation in their downward solar and thermal components. This also suggests that, globally, the simulated surface sensible and latent heat fluxes, around 20 and 85 Wm-2 on average, state realistic values. The findings of this study are compiled into a new global energy balance diagram, and may be able to reconcile currently disputed inconsistencies between global mean energy and water cycle estimates. The study is published online in Climate Dynamics. Related references: Wild, M., 2012: New Directions: A facelift for the picture of the global energy balance. Atmospheric Environment, 55, 366-367. 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., published online. Doi:10.1007/s00382-012-1569-8. Stephens, G.L., Li, J.-L., Wild, M., Clayson, C.A., Loeb, N., Kato, S., L'Ecuyer, T., Stackhouse, P.W., and Andrews, T., 2012b: An update on Earth's energy balance in light of the latest global observations, Nature Geoscience, 5, 691-696, doi:10.1038/ngeo1580.

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

2013-04-01

43

High pressure behaviour of heavy rare earth mono 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 antimonides (RESb; RE = 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 and strong mixing of f states of RE ion with the p orbital of neighboring pnictogen ion. These compounds exhibit first order crystallographic phase transition from their NaCl (B1) phase to CsCl (B2) phase at 23.6 GPa and 25.4 GPa respectively. The bulk modulii of RESb compounds are obtained from the P-V curve fitted by the Birch equation of state. We also calculated the RE-RE distance as a function of pressure. Elastic properties of these compounds have also been studied and their second order elastic constants are calculated.

44

Energy Balance and Power Performance Analysis for Satellite in Low Earth Orbit  

Science.gov (United States)

The electrical power system (EPS) of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA) power generation, the peak power tracking (PPT) method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.

Jang, Sung-Soo; Kim, Sung-Hoon; Lee, Sang-Ryool; Choi, Jaeho

2010-09-01

45

Research on Earth's rotation and the effect of atmospheric pressure on vertical deformation and sea level variability  

Science.gov (United States)

The work done under NASA grant NAG5-485 included modelling the deformation of the earth caused by variations in atmospheric pressure. The amount of deformation near coasts is sensitive to the nature of the oceanic response to the pressure. The PSMSL (Permanent Service for Mean Sea Level) data suggest the response is inverted barometer at periods greater than a couple months. Green's functions were constructed to describe the perturbation of the geoid caused by atmospheric and oceanic loading and by the accompanying load-induced deformation. It was found that perturbation of up to 2 cm are possible. Ice mass balance data was used for continental glaciers to look at the glacial contributions to time-dependent changes in polar motion, the lod, the earth's gravitational field, the position of the earth's center-of-mass, and global sea level. It was found that there can be lateral, non-hydrostatic structure inside the fluid core caused by gravitational forcing from the mantle, from the inner core, or from topography at the core/mantle or inner core/outer core boundaries. The nutational and tidal response of a non-hydrostatic earth with a solid inner core was modeled. Monthly, global tide gauge data from PSMSL was used to look at the 18.6-year ocean tide, the 14-month pole tide, the oceanic response to pressure, the linear trend and inter-annual variability in the earth's gravity field, the global sea level rise, and the effects of post glacial rebound. The effects of mantle anelasticity on nutations, earth tides, and tidal variation in the lod was modeled. Results of this model can be used with Crustal Dynamics observations to look at the anelastic dissipation and dispersion at tidal periods. The effects of surface topography on various components of crustal deformation was also modeled, and numerical models were developed of post glacial rebound.

Wahr, John

1993-03-01

46

Instability of the Ice Free Earth: Dynamics of a Discrete Time Energy Balance Model  

CERN Document Server

In late sixties, Mihail Budyko and William Sellers, a Russian and an American climate scientists, independently introduced the concept of Energy Balance Model with ice albedo feedback. Since then many have followed in their footsteps to establish various versions of this model. In this paper, a novel equation is introduced to account for the dynamics of the ice line, and is coupled to Budyko's model. We found that the coupled temperature profile-ice line system has a one dimensional center stable manifold. Furthermore, this conceptual model, that accounts only for feedback from the ice albedo and that should not be used for predictive purposes, suggests that under some climate forcings, the ice free earth is unstable.

Widiasih, E

2011-01-01

47

A new look at the Earth's radiation balance from an A-train observational perspective  

Science.gov (United States)

The weather and climate of the Earth are driven by interactions of the longwave and shortwave radiation between the Earth's atmosphere and surface. Past studies have tried to derive the Earth radiative budget through the use of models and passive satellite sensors. These past efforts did not have information about the vertical distribution of cloud or aerosols within the atmosphere that significantly influence radiative transfer within the atmosphere. This problem was improved upon with the launch of CloudSat and CALIPSO in 2006. These satellites provide the information on the vertical distribution of clouds. From CloudSat, a fluxes and heating rates product was produced to study the radiative budget, but this was limited to some degree because of undetected clouds and aerosol that have non-negligible effects on the radiative balance. This study addresses these issues by combining CALIPSO and MODIS data with CloudSat to detect and obtain the properties of cloud and aerosol undetected by the CloudSat CPR. The combined data were used to create a cloud and aerosol mask that identified distributions of undetected cloud and aerosol globally and quantified their radiative effects both seasonally and annually. Low clouds were found to have the highest impacts of nearly -6 Wm-2. High clouds globally have little effect, trapping 1 Wm-2, with the majority of the impact in the tropics. Four case studies are presented to show how heating rates change in the vertical due low cloud, cirrus, precipitation, and aerosol. The cloud and aerosol mask was used to create seasonal global distributions of cloud radiative effect using all clouds detected by CloudSat and CALIPSO, and the direct effect of aerosols estimated at the TOA. Using fluxes at the top and bottom of the atmosphere global distributions of outgoing and incoming radiation are shown, and an annual radiation budget of the Earth is derived. Clouds globally are found to have a radiative forcing of -20 Wm -2 at the TOA. The radiative budget of the Earth is calculated in two ways; Using normalized shortwave fluxes by the average solar daily insolation, and by changing the solar zenith angle to simulate the diurnal cycle. Finally, the product is validated by comparing the outgoing and surface fluxes with CERES and ISCPP flux products.

Henderson, David S.

48

Salt balance: From space experiments to revolutionizing new clinical concepts on earth - A historical review  

Science.gov (United States)

For a long time, sodium balance appeared to be a “done deal” and was thought to be well understood. However, experiments in preparation of space missions showed that the concept of osmotic sodium storage and close correlations of sodium with water balance are only part of the regulatory mechanisms of body salt. By now it has turned out that the human skin is an important storage place and regulator for sodium, that sodium storage involves macrophages which in turn salt-dependently co-regulate blood pressure, that body sodium also strongly influences bone and protein metabolism, and that immune functions are also strongly influenced by sodium. In addition, the aging process appears to lead to increased body sodium storage, which in turn might influence the aging process of the human body. The current review article summarizes the developments that have led to these revolutionizing new findings and concepts as well as consequences deriving from these findings. Therefore, it is not intended in this article to give a complete literature overview over the whole field but to focus on such key literature and considerations that led to the respective developments.

Gerzer, Rupert

2014-11-01

49

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

50

A novel pneumatic micropipette aspiration method using a balance pressure model  

Science.gov (United States)

This paper presents a novel micropipette aspiration (MA) method based on a common pneumatic micro-injection system. This method is the first to quantify the influence of capillary effect on aspiration pressure using a balance pressure model, and in return, uses the capillary effect to quantify the aspiration pressure. Subsequently, the seal between the cell and the micropipette is detected to judge and exclude the ineffective MA attempts. The rationality of the balance pressure model is validated by the designed micropipette-filling experiments. Through applied to elasticity-determination of the cells with different sizes, the feasibility and versatility of this MA method are proved. With abilities to quantify aspiration pressures and detect the seam between the cell and the micropipette, our method is expected to advance the application of the commercial pneumatic injector in the MA of cells. Moreover, with the quantified volume of the liquid entering into the micropipette during MA process, our method also has a potential applicability to the study of the permeability of the cell membrane in the future.

Zhao, Qili; Wu, Ming; Cui, Maosheng; Qin, Yanding; Yu, Jin; Sun, Mingzhu; Zhao, Xin; Feng, Xizeng

2013-12-01

51

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.

52

A new non-pressure-balanced structure in interplanetary space: Boundary layers of magnetic clouds  

Science.gov (United States)

Here is analyzed the observational data of 70 magnetic cloud boundary layers (BLs) from the Three-Dimensional (3-D) Plasma and Energetic Particle (3DP) and 50 BLs from the Solar Wind Experiment (SWE) instruments on Wind spacecraft from February 1995 to June 2003. From this analysis, we discover that the boundary layer of a magnetic cloud is a new non-pressure-balanced structure different from the jump layer (i.e., shocked front) of an interplanetary shock wave. The main results are that (1) the BL is often a non-pressure-balanced structure with the magnetic pressure decrease associated with the abrupt variation of field direction angle (?, ?) for about 90% and more than 85% of the BLs investigated from 3DP and SWE data, respectively; (2) the events of heated and accelerated plasma in the BLs are about 90%, 85% and 85%, 82% of the BLs investigated, respectively, from 3DP and SWE data; (3) the reversal flows are observed and their occurrence ratio is as high as 80% and 90% of the BLs investigated from 3DP and SWE data, respectively; and (4) the plasma and field characteristics for the BLs are also obviously different from those in the jump layers (JLs) of shock waves. These results show that there exist important dynamic interactions inside the BLs. As a preliminary interpretation, this could be associated with the magnetic reconnection process possibly occurring inside the BLs. Thus the study of the BLs, as a new non-pressure-balanced structure in interplanetary space, could open a "new window" for revealing some important physical processes in interplanetary space.

Wei, Fengsi; Feng, Xueshang; Yang, Fang; Zhong, Dingkun

2006-03-01

53

Performance of pressure control valves and flow meters precision in operational irrigation-water balance accuracy  

Science.gov (United States)

In pressure irrigation-water distribution networks, pressure regulating devices for controlling the discharged flow rate by irrigation units are needed due to the variability of flow rate. In addition, applied water volume is used controlled operating the valve during a calculated time interval, and assuming constant flow rate. In general, 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. Its lecture could be used for refining the water balance but its accuracy must be taken into account. Ideal PRV performance would maintain a constant downstream pressure. However, the true performance depends on both upstream pressure and the discharged flow rate. The objective of this work is to asses the influence of the performance on the applied volume during the whole irrigation events in a year. The results of the study have been obtained introducing the flow rate into a PRV model. 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 the PRV.

Sánchez, R.; Rodríguez-Sinobas, L.; Juana, L.; Laguna, F. V.; Gil, M.; Benítez, J.

2012-04-01

54

Gas flow and pressure balancing in modeling grate/kiln induration  

Science.gov (United States)

The performance of iron-ore pellet induration plants, including their energy consumption, is critically dependent on the relative flowrates and conditions of gas streams involved in the process. Equations and procedures for gas flow and pressure balance calculations within a dynamic mathematical model of the complete grate/kiln induration process are presented. Detailed simulation results, including pellet temperature profiles, enthalpy balances, and heat losses for a particular operating plant are discussed. Energy consumption per tonne of product changes appreciably with production rate, and there is a rate at which the specific fuel usage is minimized. Fuel oil consumption is increased if part of the oil is burned in the grate furnace rather than in the kiln.

Thurlby, J. A.

1988-02-01

55

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

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

Nonlinear pressure effects in superconducting rare earth-iron-silicides  

International Nuclear Information System (INIS)

The superconducting transition temperatures (Tsub(c)) of RE2Fe3Si5 (RE = Sc, Y, Lu) vary in a nonlinear fashion under hydrostatic pressure up to 20 kbar. For the Sc and Lu compounds Tsub(c) decreases at an average rate of -7x10-5K bar-1, while Tsub(c) of Y2Fe3Si5 increases rapidly (33x10-5K bar-1) and passes through a maximum whose value is twice that at ambient pressure. The results are compared with the effects of volume contraction across the series (Ysub(1-x)Lusub(x))2Fe3Si5 and (Ysub(1-x)Dysub(x))2Fe3Si5. (Auth.)

58

Pressure dependence of the charge-density-wave gap in rare-earth tritellurides.  

Science.gov (United States)

We investigate the pressure dependence of the optical properties of CeTe3, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the midinfrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe3. PMID:17358625

Sacchetti, A; Arcangeletti, E; Perucchi, A; Baldassarre, L; Postorino, P; Lupi, S; Ru, N; Fisher, I R; Degiorgi, L

2007-01-12

59

Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides  

Energy Technology Data Exchange (ETDEWEB)

We investigate the pressure dependence of the optical properties of CeTe{sub 3}, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe{sub 3}.

Sacchetti, A.; /Zurich, ETH; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P.; Lupi, S.; /Rome U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.; Degiorgi, L.; /Zurich, ETH

2009-12-14

60

Pressure dependence of the charge-density-wave gap in rare-earth tri-tellurides  

CERN Document Server

We investigate the pressure dependence of the optical properties of CeTe$_3$, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of $R$Te$_3$.

Sacchetti, A; Perucchi, A; Baldassarre, L; Postorino, P; Lupi, S; Ru, N; Fisher, I R; Degiorgi, L

2006-01-01

 
 
 
 
61

Errors in water retention curves determined with pressure plates: Effects on the soil water balance  

Science.gov (United States)

Pressure plates apparatus are very common experimental devices utilized to measure the soil water retention curve. Many studies have demonstrated the lack of reliability of pressure plates apparatus when they are used to measure the soil water retention curve in the dry range, due to low plate and soil conductance, lack of hydrostatic equilibrium, lack of soil-plate contact and soil dispersion. In this research, we investigated measurements of soil water retention curves obtained with a combination of Stackman's tables, pressure plates apparatus and the chilled-mirror dew point technique. Specifically, the aim of this research was: (a) to investigate the differences in the measured soil water retention curves by the different experimental methods, (b) evaluate relationships between the experimental differences and soil texture, (c) analyze the effect of experimental differences on hydraulic properties parameterization and (d) investigate the effects of the different parameters set on water transport computation. The results showed differences in measurements made by the combination of Stackman's tables and Richards' pressure plates apparatus as compared to the dew point method, for fine textured soils, while no significant differences were detected for coarse textured soils. Computed cumulative drainage and evaporation displayed lower values if soil water retention curves were obtained from data obtained with the Stackman's tables and Richards' pressure plates apparatus instead of the dew point method. In soils, where the soil water retention curve was measured with traditional methods (Stackman's tables and Richards' pressure plates apparatus) average cumulative drainage was 173 mm, with respect to a combination of methods including the dew point methods, where the average cumulative drainage was 184 mm. Average cumulative evaporation was 77 mm for the traditional methods, while it was 91 mm, for the combination of methods. Overall, when simulation models are used for studies related to solute transport, polluted soil remediation, irrigation management and others, erroneous measurement of the SWRC for fine textured soils, may lead to erroneous computation of the soil water balance.

Solone, R.; Bittelli, M.; Tomei, F.; Morari, F.

2012-11-01

62

Energy balance of a high-pressure cesium pulsed discharge in a transparent capillary  

Energy Technology Data Exchange (ETDEWEB)

An experimental evaluation was made of the various components of the energy balance of a pulsed high-pressure cesium discharge (Papprox.10/sup 2/-10/sup 3/ atm) in a transparent thick-walled capillary. It is shown that, with the selected parameters of the discharge, the contribution of the thermal lag of the plasma and of longitudinal dissipation of heat to the energy of the process is negligibly small. It is brought out that the positive column of a discharge of the given type is a continuously ventilated cesium plasma filament, surrounded by a thin shell of the vapors of a material of the wall, to which the Elenbaas-Heller equation for steady-state radiative thermal conductivity is applicable.

Barol' skii, S.G.; Ermokhin, N.V.; Kulik, P.P.; Ryabyi, V.A.

1977-01-01

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

Pressure-induced structural transition and long-period structures of rare-earth metal hydrides  

International Nuclear Information System (INIS)

Pressure-induced structural transition of rare-earth metal hydride, YH3, has been investigated by synchrotron radiation X-ray diffraction experiments. We observed the pressure-induced structural transformation from the hexagonal metal lattice into an fcc one through an intermediate state, which appears in the wide pressure span of 12-22 GPa. The obtained X-ray diffraction patterns in the intermediate state are represented by long-period structures, e.g. 27R, of the yttrium metal lattice. These long-period structures are interpreted in terms of the periodic arrangements of hexagonal-type and fcc-type stacking layers of the yttrium metals. Such structural transition is considered to be characteristic for rare-earth metal hydride. (author)

65

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

66

The plastic deformation of iron at pressures of the Earth's inner core  

Science.gov (United States)

Soon after the discovery of seismic anisotropy in the Earth's inner core, it was suggested that crystal alignment attained during deformation might be responsible. Since then, several other mechanisms have been proposed to account for the observed anisotropy, but the lack of deformation experiments performed at the extreme pressure conditions corresponding to the solid inner core has limited our ability to determine which deformation mechanism applies to this region of the Earth. Here we determine directly the elastic and plastic deformation mechanism of iron at pressures of the Earth's core, from synchrotron X-ray diffraction measurements of iron, under imposed axial stress, in diamond-anvil cells. The epsilon-iron (hexagonally close packed) crystals display strong preferred orientation, with c-axes parallel to the axis of the diamond-anvil cell. Polycrystal plasticity theory predicts an alignment of c-axes parallel to the compression direction as a result of basal slip, if basal slip is either the primary or a secondary slip system. The experiments provide direct observations of deformation mechanisms that occur in the Earth's inner core, and introduce a method for investigating, within the laboratory, the rheology of materials at extreme pressures. PMID:10890442

Wenk; Matthies; Hemley; Mao; Shu

2000-06-29

67

Blood pressure and fluid-electrolyte balance in mice with reduced or absent ANP.  

Science.gov (United States)

Atrial natriuretic peptide (ANP)-gene knockout mice of three genotypes (+/+, +/-, and -/-) were maintained on a low-salt diet (0.008% NaCl). They were then fed either the same low-salt diet or a high-salt diet (8% NaCl) for 1 wk. No differences were found among genotypes in daily food and water intakes or in urinary volume and electrolyte excretions. Arterial blood pressures measured in anesthetized animals at the end of the dietary regimen were significantly and similarly increased in -/- compared with +/+ mice on each diet. Renal excretion of fluid and electrolytes was measured in anesthetized mice before and after acute blood volume expansion. No genotype differences were observed before volume expansion. After volume expansion the wild-type (+/+) mice had much greater saluretic responses than either the heterozygous (+/-) or the homozygous mutant (-/-) animals on the low-salt diet but not on the high-salt diet. We conclude that ANP lowers blood pressure in the absence of detected changes in renal function; ANP is not essential for normal salt balance, even on high-salt intake; and ANP is essential for the natriuretic response to acute blood volume expansion on a low-salt but not high-salt intake. PMID:8760210

John, S W; Veress, A T; Honrath, U; Chong, C K; Peng, L; Smithies, O; Sonnenberg, H

1996-07-01

68

Anthropogenic and natural exergy losses (exergy balance of the Earth's surface and atmosphere)  

International Nuclear Information System (INIS)

Natural exergy losses connected with the absorption of solar radiation by the Earth have been calculated. The exergy income caused by the radiation exchange between the Earth and the cosmic space has also been considered. The exergy losses occurring near the Earth's surface have been distinguished because they represent the most accessible natural resources of exergy. The term 'natural losses of utilizable exergy' has been proposed. These losses have been compared with the anthropogenic ones caused by the activity of humankind. The positive impact of the natural exergy losses has been pointed out: they were a main cause of the formation of the terrestrial natural environment, of the non-renewable natural resources of fuels, and of the generation of stable dissipative structures in form of living beings

69

Digitalis-like activity in human plasma: Relation to blood pressure and sodium balance  

Energy Technology Data Exchange (ETDEWEB)

PURPOSE: On the assumption that renal tubular cells are more important as the target cells for a natriuretic factor than blood cells, we used a well-characterized cultured renal tubular cell line, Madin-Darby canine kidney (MDCK), cells to monitor the circulating digitalis-like factor in human plasma and examine its role in the regulation of blood pressure and sodium balance. SUBJECTS AND METHODS: We investigated the effects of plasma on binding of radioactive ouabain to monolayered MDCK cells in order to determine the level of a circulating digitalis-like factor. First, we measured specific 3H-ouabain binding to MDCK cells in the presence of plasma from 71 outpatients (34 normotensive subjects and 37 hypertensive patients) after incubation for 4 hours. Second, we measured specific 3H-ouabain binding after incubation of cells with plasma from 16 hospitalized subjects (eight normotensive subjects and eight hypertensive patients) receiving low and high sodium diets. RESULTS: In Study 1, ouabain binding was lower by 30% with plasma from hypertensive patients than with plasma from normotensive subjects (p less than 0.01). There was a significant negative correlation between individual subject's systolic or mean blood pressure and ouabain binding (r = -0.34, p less than 0.01 or r = -0.29, p less than 0.01). In Study 2, ouabain binding was also significantly reduced by 25% in the presence of plasma from hypertensive subjects as compared with plasma from normotensive subjects irrespective of sodium intake (p less than 0.01). A significant negative correlation was also found for all subjects between either systolic, diastolic, or mean blood pressure and ouabain binding (r = -0.58, p less than 0.01, r = -0.51, p less than 0.01, or r = -0.55, p less than 0.01, respectively).

Goto, A.; Yamada, K.; Ishii, M.; Sugimoto, T. (Univ. of Tokyo (Japan))

1990-10-01

70

Digitalis-like activity in human plasma: Relation to blood pressure and sodium balance  

International Nuclear Information System (INIS)

PURPOSE: On the assumption that renal tubular cells are more important as the target cells for a natriuretic factor than blood cells, we used a well-characterized cultured renal tubular cell line, Madin-Darby canine kidney (MDCK), cells to monitor the circulating digitalis-like factor in human plasma and examine its role in the regulation of blood pressure and sodium balance. SUBJECTS AND METHODS: We investigated the effects of plasma on binding of radioactive ouabain to monolayered MDCK cells in order to determine the level of a circulating digitalis-like factor. First, we measured specific 3H-ouabain binding to MDCK cells in the presence of plasma from 71 outpatients (34 normotensive subjects and 37 hypertensive patients) after incubation for 4 hours. Second, we measured specific 3H-ouabain binding after incubation of cells with plasma from 16 hospitalized subjects (eight normotensive subjects and eight hypertensive patients) receiving low and high sodium diets. RESULTS: In Study 1, ouabain binding was lower by 30% with plasma from hypertensive patients than with plasma from normotensive subjects (p less than 0.01). There was a significant negative correlation between individual subject's systolic or mean blood pressure and ouabain binding (r = -0.34, p less than 0.01 or r = -0.29, p less than 0.01). In Study 2, ouabain binding was also significantly reduced by 25% in the presence of plasma from hypertensive subjects as compared with plasma from normotensive subjects irrespective of sodium intake (p less than 0.01). A significant negative correlation was also found for all subjects between either systolic, diastolic, or mean blood pressure and ouabain binding (r = -0.58, p less than 0.01, r = -0.51, p less than 0.01, or r = -0.55, p less than 0.01, respectively)

71

Reliability and Sex Differences in the Foot Pressure Load Balance Test and Its Relationship to Physical Characteristics in Preschool Children  

Directory of Open Access Journals (Sweden)

Full Text Available This study aimed to examine the trial-to-trial reliability and sex differences in a foot pressure load balance test and its relationship to physical characteristics in 396 preschool children (201 boys and 195 girls. The subjects were asked to maintain an upright standing posture for 10 seconds three times on the Footview Clinic, an instrument designed to calculate the right-left and anterior-posterior ratios of foot pressure load. The ratios of the left and anterior foot pressure loads in right and left feet were selected as variables. Intra-class correlation coefficients between the second and third trials in all variables were high (intra-class correlation coefficients = 0.70 - 0.90. The above variables showed insignificant sex differences and little relationships with physique. When measuring foot pressure load balance, it is desirable to use a mean of the second and third trials as a representative.

Kosho Kasuga

2012-05-01

72

Earth's core-mantle boundary - Results of experiments at high pressures and temperatures  

Science.gov (United States)

Laboratory experiments document that liquid iron reacts chemically with silicates at high pressures (above 2.4 x 10 to the 10th Pa) and temperatures. In particular, (Mg,Fe)SiO3 perovskite, the most abundant mineral of earth's lower mantle, is expected to react with liquid iron to produce metallic alloys (FeO and FeSi) and nonmetallic silicates (SiO2 stishovite and MgSiO3 perovskite) at the pressures of the core-mantle boundary, 14 x 10 to the 10th Pa. The experimental observations, in conjunction with seismological data, suggest that the lowermost 200 to 300 km of earth's mantle, the D-double-prime layer, may be an extremely heterogeneous region as a result of chemical reactions between the silicate mantle and the liquid iron alloy of earth's core. The combined thermal-chemical-electrical boundary layer resulting from such reactions offers a plausible explanation for the complex behavior of seismic waves near the core-mantle boundary and could influence earth's magnetic field observed at the surface.

Knittle, Elise; Jeanloz, Raymond

1991-01-01

73

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

74

Magnetopause pressure balance in subsolar point during northward IMF orientation and high level of turbulence in magnetosheath in accordance with THEMIS data  

International Nuclear Information System (INIS)

Complete text of publication follows. Plasma static and dynamic, magnetic pressure variations at the subsolar point of the magnetosphere of the Earth are studied using data of THEMIS satellites. The interval when interplanetary magnetic field (IMF) had the northward orientation and magnetopause crossings had features near to the tangentional discontinuity was selected. 18 magnetopause crossings were analyzed. Great variations of plasma flow parameters and magnetic field were simultaneously observed in the magnetosheath (turbulent magnetosheath). It is shown that in spite of such great magnetosheath variations and limited applicability of MHD approximation to the noncollisional plasma, the condition of stress balance is fulfilled in the limited regions near magnetopause just before the magnetopause and after it. The problem of magnetosheath plasma penetration inside the magnetosphere is discussed.

75

Sodium intake and cardiac sympatho-vagal balance in young men with high blood pressure.  

Science.gov (United States)

We have previously reported that a high sodium intake increases sleep-time blood pressure (BP) in young men. However, there are cases in which this relation does not apply. To account for them, we investigated the relation between sodium intake and cardiac sympatho-vagal balance (SVB) in young men with high BP. Sodium intake was estimated from the amount of urinary sodium excretion over 1 week. Twenty-four-hour (24-h) urinary sodium excretion (Salt24), 24-h ambulatory BP and ECG were obtained on the last day of the observation period. As an index of sodium intake, the expression In(Salt24/Cr24) (Cr24, 24-h urinary creatinine excretion) was used. From power-spectral analysis of ECG-RR intervals during sleep, we obtained the LF/HF ratio between the low-frequency component (LF) and the high frequency component (HF) and used it as an index of SVB. The subjects were male medical students divided into a normal BP group (N-group; n=103) and a high BP group (H-group; n=26, 24-h BP>125/75 mmHg). Mean In(Salt24/Cr24) and LF/HF in the H-group were significantly higher than those in the N-group (LF/HF: 1.86+/-0.44 [SD] vs. 1.37+/-0.30, pSVB (LF/HF) increases BP in young men. PMID:15253104

Tochikubo, Osamu; Nishijima, Kiyoko

2004-06-01

76

Transport coefficients and entropy-scaling law in liquid iron up to Earth-core pressures.  

Science.gov (United States)

Molecular dynamics simulations were applied to study the structural and transport properties, including the pair distribution function, the structure factor, the pair correlation entropy, self-diffusion coefficient, and viscosity, of liquid iron under high temperature and high pressure conditions. Our calculated results reproduced experimentally determined structure factors of liquid iron, and the calculated self-diffusion coefficients and viscosity agree well with previous simulation results. We show that there is a moderate increase of self-diffusion coefficients and viscosity along the melting curve up to the Earth-core pressure. Furthermore, the temperature dependencies of the pair correlation entropy, self-diffusion, and viscosity under high pressure condition have been investigated. Our results suggest that the temperature dependence of the pair correlation entropy is well described by T(-1) scaling, while the Arrhenius law well describes the temperature dependencies of self-diffusion coefficients and viscosity under high pressure. In particular, we find that the entropy-scaling laws, proposed by Rosenfeld [Phys. Rev. A 15, 2545 (1977)] and Dzugutov [Nature (London) 381, 137 (1996)] for self-diffusion coefficients and viscosity in liquid metals under ambient pressure, still hold well for liquid iron under high temperature and high pressure conditions. Using the entropy-scaling laws, we can obtain transport properties from structural properties under high pressure and high temperature conditions. The results provide a useful ingredient in understanding transport properties of planet's cores. PMID:24655191

Cao, Qi-Long; Wang, Pan-Pan; Huang, Duo-Hui; Yang, Jun-Sheng; Wan, Ming-Jie; Wang, Fan-Hou

2014-03-21

77

Differential Velocity between Solar Wind Protons and Alpha Particles in Pressure Balance Structures  

Science.gov (United States)

Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advected into and reconnects with the flux concentration. A minimum variance analysis (MVA) of magnetic discontinuities in PBSs showed there is a larger proportion of tangential discontinuities than in the surrounding high-speed wind, supporting the hypothesis that plasmoids or extended current sheets are formed during reconnection at the base of plumes. To further evaluate the character of magnetic field discontinuities in PBSs, differential streaming between alpha particles and protons is analyzed here for the same sample of PBSs used in the MVA. Alpha particles in high-speed wind generally have a higher radial flow speed than protons. However, if the magnetic field is folded back on itself, as in a large-amplitude Alfven wave, alpha particles will locally have a radial flow speed less than protons. This characteristic is used here to distinguish between folded back magnetic fields (which would contain rotational discontinuities) and tangential discontinuities using Ulysses high-latitude, high-speed solar wind data. The analysis indicates that almost all reversals in the radial magnetic field in PBSs are folded back field lines. This is found to also be true outside PBSs, supporting existing results for typical high-speed, high-latitude wind. There remains a small number of cases that appear not to be folds in the magnetic field and which may be flux tubes with both ends rooted in the Sun. The distinct difference in MVA results inside and outside PBSs remains unexplained.

Yamauchi, Yohei; Suess, Steven T.; Steinberg, John T.; Sakurai, Takashi

2004-01-01

78

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

79

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

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

Effect of load cycle operation on reactivity balance and power density distribution in WWER-type pressurized water reactors  

International Nuclear Information System (INIS)

Starting from a quasistationary reactivity balance, the control reactivity needed for load cycle operation and the resulting power density distribution have been determined using a point model and a one-dimensional model. The models can be applied to different types of the daily scheduled load operation (sinusoidal, trapezoidal, and ramp-shaped) as well as to any other control concepts. The sinusoidal load cycle operation at constant main steam pressure has been determined to be the most preferable one. (author)

82

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

83

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

84

Variations of the Earth's figure axis caused by pressure changes in the core  

Science.gov (United States)

Significant variations in the degree two and order one geopotential coefficients: C21 and S21 have been observed from analysis of the Satellite Laser Ranging (SLR) and GRACE data. The geopotential coefficients: C21and S21, from SLR and GRACE data determine the principal figure axis of the entire Earth with respect to the z-axis of the terrestrial reference system as defined by the mean rotation axis on the mantle. The changes in the pattern of flow in the core result in the pressure variations acting at the core-mantle boundary (CMB), in turn, cause deformation of the mantle and produce a torque on the core. Thus, the observed mean figure axis from the recent GRACE and SLR solution could provide improved constant on the Earth's core dynamics: tilt of the core figure axis from the mantle axis. We investigate the effects on the variations of the C21/S21 and lower degree zonal harmonics coefficients due to the surface deformation and torque changes of the mantle induced by the fluid pressure at CMB.

Cheng, Minkang; Fang, Ming

2010-05-01

85

Potassium partitioning into molten iron alloys at high-pressure: Implications for Earth's core  

Science.gov (United States)

It has long been known that the Earth's mantle is more depleted in potassium, than C1-chondrites [1,2]. Two major mechanisms could explain this depletion: (i) the depletion is due to potassium volatility during the early stages of planetary accretion, or (ii) potassium has been incorporated into the core during segregation of an iron-rich metallic liquid. The potassium isotopic composition data of most solar system material place strong limits of 2% on the quantity of potassium that could have been lost by volatilization, ruling out any considerable volatilization or evaporation of potassium [3]. Thus, at least part of the potassium deficit in the mantle might be due to the incorporation of K into the core. To provide strong constraints on the potassium content of the core at the time of Earth's formation, multi-anvil experiments were carried out to determine the partition coefficients of potassium between molten silicates and iron alloy liquids (S-free and S-bearing alloys), between 5 and 15 GPa, at a temperature of 2173 K, and at an oxygen fugacity about 2 log units below the iron-wustite (IW) buffer. No pressure dependence of the potassium partition coefficients in S-free and S-bearing systems was found within the investigated pressure range. We also shown that the degree of melt polymerization is not a controling factor for K partitioning in compositions relevant to the Earth's mantle. We review all available high-pressure data to obtain reliable partition coefficients for the interaction between molten silicates and Fe-alloy liquids at pressures and temperatures relevant to those of core formation in a terrestrial magma ocean. All the existing data, for an oxygen fugacity of about 2 orders of magnitude lower than the IW buffer, and for compositions relevant to the Earth's mantle, and at 2173 K plot around a constant value of 0.083 ± 0.051 and 0.0063 ± 0.0019 for S-bearing and S-free metal, respectively [4]. The dominant controlling parameters appear to be the temperature and the chemical composition of the metallic phase, with potassium partitioning coefficients significantly increased with temperature, and with the sulphur and oxygen contents of the Fe-alloy liquid. Our considerations distinguish too extreme cases, with an S-free or S-rich iron core, which yield K-contents of ~25 or ~250 ppm, respectively. These two extreme values have very different consequences for thermal budget models of the Earth's core since its formation. [1] Gast, P.W., 1960. J. Geophys. Res. 65, 1287. [2] Wasserburg, G.J. et al. 1964. Science 143, 465. [3] Humayon, M., Clayton, R.N., 1995. Geochim. Cosmochim. Acta 59, 2131. [4] Bouhifd, M.A. et al. 2006. Phys. Earth Planet. Int., (under review).

Bouhifd, M.; Gautron, L.; Bolfan-Casanova, N.; Malavergne, V.; Hammouda, T.; Andrault, D.; Jephcoat, A.

2006-12-01

86

Metal-silicate partitioning of potassium at high pressure and temperature conditions and implications for thermal history of the Earth  

Science.gov (United States)

The possible presence of potassium in the Earth's core as a radioactive heat source can have a significant influence on the thermal evolution of the Earth (Buffett, 2002 GRL; Labrosse, 2003 PEPI). Core-mantle equilibration at high P-T (e.g. ~30 GPa, ~3450 K [Righter, 2011 EPSL]) was suggested from the mantle contents of siderophile elements. Basal magma ocean (Labrosse et al., 2007 Nature) also should be equilibrated with molten iron at the core-mantle boundary (CMB) (~135 GPa) due to its gravitational stability (Nomura et al., 2011 Nature). Previous experimental studies on potassium partitioning between liquid metal and silicate melt showed contradictory results on the concentration of potassium in the Earth's core because of experimental artifacts (K loss in metal phase), different (simplified) chemical compositions for study and large extrapolations to high P-T which suits for core-mantle equilibration at the base of the magma ocean. Recently, Corgne et al. (2007 EPSL) performed the partitioning experiments up to 7.7 GPa and 2200°C with chemical compositions of CI chondrite doped with moderate amount of S and K and revealed a significant effect of O contents in molten alloy on K partition coefficient while with negligible effect of P-T and S and C contents. The change in electronic structure of potassium from 4s- to 3d-like was predicted by theory (Bukowinski, 1976 GRL) and potassium alloying with nickel and iron was reported by experiments using diamond anvil cell at ~30 GPa and 2200 K (Parker et al., 1997 Science; Lee and Jeanloz, 2003 GRL). So, it is important to investigate the effect of pressure on K partition coefficient at the pressure conditions above ~30 GPa up to 135 GPa. Hirao et al. (2006 GRL) performed melting experiment at 135 GPa and 3500 K using laser-heated diamond anvil cell (LHDAC) and showed the value of partition coefficient Dk is 0.15, but their results lack the elemental mass balances between run products and starting materials. Our melting experiments were performed at high P-T conditions using LHDAC. Fine powdered mixtures of Fe (or Fe-FeS, Fe-FeSi) metal and gels with chemical compositions of KLB-1 peridotite doped with 1wt% K were used as a starting material. The gel powder was dehydrated by heating to 1273 K for 1 h in a H2-CO2 gas mixing furnace, in which oxygen fugacity was controlled to be slightly above the iron-wustite buffer. Pressure was measured after quenching with the Raman shift of diamond anvil. Ar was used as a pressure medium. The sample was heated from double side using Nd:YLF laser. A recovered sample was processed with Ion Slicer (JEOL EM-09100 IS), and subsequently examined by energy-dispersive X-ray spectrometry (EDS) attached with field emission scanning electron microscope (FE-SEM: JOEL JSM-7000F). Our preliminary results at ~20 GPa, fO2 of ~IW-1 and high temperature up to 5000 K with KLB-1 gel and S-free metal shows the clear correlation between O contents in molten iron and K partition coefficients suggested by Corgne et al. (2007). The results of partitioning coefficient at high P-T range up to primordial CMB conditions will be discussed in our presentation.

Nomura, R.; Hirose, K.

2011-12-01

87

Earth  

International Nuclear Information System (INIS)

Results of investigations into the Earth composition are discussed. Composition of the core mantle and crust are considered in detail. The Earth is shown to be strongly differentiated. Probably, the core comprises three elements: Fe, Ni, S. 9 elements: O, Si, Al, Fe, Mg, Ca, Na, K and Ti (without account of water) make up more than 99% of the crust

88

Upper Airway Anatomical Balance Contributes to Optimal Continuous Positive Airway Pressure for Japanese Patients with Obstructive Sleep Apnea Syndrome  

Science.gov (United States)

Background: The aim of this study was to examine whether the upper airway anatomical balance, as reflected by tongue size relative to maxillomandibular size, is related to optimal nasal continuous positive airway pressure (PnCPAP). Methods: Sixty-six male Japanese obstructive sleep apnea syndrome (OSAS) patients (median apnea-hypopnea index [AHI] = 33.9 episodes/h [10th/90th percentile = 19.5/59.9], median body mass index [BMI] = 25.1 kg/m2 [10th/90th percentile = 21.2/30.4]) were recruited. All patients underwent standard polysomnography (PSG), and PnCPAP was determined by nasal continuous positive airway pressure (nCPAP) titration. The anatomical balance was defined as the tongue area (TG) divided by the lower face cage (LFC) measured on cephalometry. A predictive equation of PnCPAP was created using demographic, polysomnographic, and cephalometric variables. Results: Significant correlations were found between PnCPAP and descriptive variables, including BMI, AHI, lowest SpO2, distance from the anterosuperior point of the hyoid bone to the mandibular plane (MP-H), and TG/LFC. Stepwise multiple regression analysis revealed that AHI and TG/LFC were independent predictors of PnCPAP. The predictive equation was: PnCPAP = 1.000 + 0.043 × AHI + 9.699 × TG / LFC, which accounted for 28.0% of the total variance in PnCPAP (R2 = 0.280, p < 0.01). Conclusions: Anatomical balance of upper airway in addition to the severity of OSAS is an important contributing factor for PnCPAP in Japanese OSAS patients. Citation: Ito E; Tsuiki S; Namba K; Takise Y; Inoue Y. Upper airway anatomical balance contributes to optimal continuous positive airway pressure for Japanese patients with obstructive sleep apnea syndrome. J Clin Sleep Med 2014;10(2):137-142. PMID:24532996

Ito, Eiki; Tsuiki, Satoru; Namba, Kazuyoshi; Takise, Yuji; Inoue, Yuichi

2014-01-01

89

Global mechanisms in atmosphere models and a balance of the Earth angle moment. Atmosphere radio-waveguides and teleconnection  

International Nuclear Information System (INIS)

Complete text of publication follows. The satellite data and data of observing the radio-waveguide parameters (especially in the low troposphere layers) by means of radio-technical devices (in the ultra short-wave diapason) is the informative basis of the modern atmosphere long-termed forecasts. As any water quantities in atmosphere are formed on the basis of the cycle- and front-genesis (or in the convective non-stability lines) one can introduce the corresponding model on the basis of thermodynamics and hydro-mechanics of the corresponding processes [1,2]. For example, physics of these processes can coincide with the soliton mechanics, which has the long-periodical basis of the energy support. The action mechanics of such a soliton defines the key thermo-hydro-dynamical parameters of the atmosphere ultra-short-wave radio-waveguide. We present new approach to modeling a role of the atmosphere circulations forms in definition of the long-periodical processes in atmosphere, parameters of the troposphere ultra-short-wave radio-waveguides and the Earth angle momentum balance. We carried out a series of the computer experiments to provide new predictors for the long-termed and super long-termed forecasts of the low frequency atmospheric processes. Besides, we have adapted the modified theory of the macro-turbulence for possible using the atmosphere radio-waveguides as a special effective predictors in the long-termed plan.

90

Thermodynamics of the Earth's core materials based on high-pressure experimental data  

Science.gov (United States)

Thermodynamics of iron and iron alloys are of crucial information for understanding of the composition, structure, and evolution of the Earth's core. Recent accumulated data from static high-pressure and -temperature experiments allows us to model the thermodynamic properties of both solid and liquid phases. In the present study, I examined the thermodynamics of the melting relations in the system Fe-FeO to the outer core-inner core boundary pressure from the latest static high-pressure and -temperature experiments. The modeling is divisible into (i) for end-member phases of Fe and FeO and (ii) for a liquid with an intermediate composition. (i) For the pure Fe system, I have included a recent laser-heated diamond anvil cell data on melting up to 200 GPa (ref.1) and pressure-volume-temperature data for face-centered cubic phase examined in a multi-anvil apparatus (ref. 2). (ii) At low pressures, non-ideality has been recognized for liquids in the system Fe-FeO. In the present study however, with the ideal solution model assumed for liquids under the core pressures, the calculated eutectic temperatures are not inconsistent with the results of the laser-heated DAC experiments showing a solid assemblage Fe+FeO was stable up to 4200 K (ref. 3). This indicates that the non-ideality decreases with increasing pressure and temperature and may diminish under the core conditions. The new solution model, namely ideal solution, predicts that the eutectic composition is about Fe-9.5 wt.%O, almost constant under the core pressures, which compositions would put the limit of the oxygen content in the core because the density of solid FeO is too small to match the inner core density. Thermodynamics allows us to derive the properties that are difficult to directly constrain by experiment. From the Gibbs free energy for the Fe-FeO liquids, I calculated the density, sound velocity, and adiabatic temperature gradient of a hypothetical oxygen-bearing outer core. I will show the effects of oxygen on the sound velocity and density of liquid iron under the outer core conditions. Also, I will discuss the distribution of oxygen in the outer core. Ref. 1. Anzellini et al. (2013 Science); 2. Tsujino et al (2013 EPSL); 3. Ozawa et al. (2011 Science)

Komabayashi, T.

2013-12-01

91

First-principles modelling of Earth and planetary materials at high pressures and temperatures  

Energy Technology Data Exchange (ETDEWEB)

Atomic-scale materials modelling based on first-principles quantum mechanics is playing an important role in the science of the Earth and the other planets. We outline the basic theory of this kind of modelling and explain how it can be applied in a variety of different ways to probe the thermodynamics, structure and transport properties of both solids and liquids under extreme conditions. After a summary of the density functional formulation of quantum mechanics and its practical implementation through pseudopotentials, we outline the simplest way of applying first-principles modelling, namely static zero-temperature calculations. We show how calculations of this kind can be compared with static compression experiments to demonstrate the accuracy of first-principles modelling at pressures reached in planetary interiors. Noting that virtually all problems concerning planetary interiors require an understanding of materials at high temperatures as well as high pressures, we then describe how first-principles lattice dynamics gives a powerful way of investigating solids at temperatures not too close to the melting line. We show how such calculations have contributed to important progress, including the recent discovery of the post-perovskite phase of MgSiO{sub 3} in the D'' layer at the base of the Earth's mantle. A range of applications of first-principles molecular dynamics are then reviewed, including the properties of metallic hydrogen in Jupiter and Saturn, of water, ammonia and methane in Uranus and Neptune, and of oxides and silicates and solid and liquid iron and its alloys in the Earth's deep interior. Recognizing the importance of phase equilibria throughout the planetary sciences, we review recently developed techniques for the first-principles calculation of solid and liquid free energies, melting curves and chemical potentials of alloys. We show how such calculations have contributed to an improved understanding of the temperature distribution and the chemical composition throughout the Earth's interior. The review concludes with a summary of the present state of the field and with some ideas for future developments.

Gillan, M J [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Alfe, D [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Brodholt, J [Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Vocadlo, L [Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Price, G D [Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2006-08-15

92

First-principles modelling of Earth and planetary materials at high pressures and temperatures  

Science.gov (United States)

Atomic-scale materials modelling based on first-principles quantum mechanics is playing an important role in the science of the Earth and the other planets. We outline the basic theory of this kind of modelling and explain how it can be applied in a variety of different ways to probe the thermodynamics, structure and transport properties of both solids and liquids under extreme conditions. After a summary of the density functional formulation of quantum mechanics and its practical implementation through pseudopotentials, we outline the simplest way of applying first-principles modelling, namely static zero-temperature calculations. We show how calculations of this kind can be compared with static compression experiments to demonstrate the accuracy of first-principles modelling at pressures reached in planetary interiors. Noting that virtually all problems concerning planetary interiors require an understanding of materials at high temperatures as well as high pressures, we then describe how first-principles lattice dynamics gives a powerful way of investigating solids at temperatures not too close to the melting line. We show how such calculations have contributed to important progress, including the recent discovery of the post-perovskite phase of MgSiO3 in the D'' layer at the base of the Earth's mantle. A range of applications of first-principles molecular dynamics are then reviewed, including the properties of metallic hydrogen in Jupiter and Saturn, of water, ammonia and methane in Uranus and Neptune, and of oxides and silicates and solid and liquid iron and its alloys in the Earth's deep interior. Recognizing the importance of phase equilibria throughout the planetary sciences, we review recently developed techniques for the first-principles calculation of solid and liquid free energies, melting curves and chemical potentials of alloys. We show how such calculations have contributed to an improved understanding of the temperature distribution and the chemical composition throughout the Earth's interior. The review concludes with a summary of the present state of the field and with some ideas for future developments.

Gillan, M. J.; Alfè, D.; Brodholt, J.; Vocadlo, L.; Price, G. D.

2006-08-01

93

Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle.  

Science.gov (United States)

The mineral olivine dominates the composition of the Earth's upper mantle and hence controls its mechanical behaviour and seismic anisotropy. Experiments at high temperature and moderate pressure, and extensive data on naturally deformed mantle rocks, have led to the conclusion that olivine at upper-mantle conditions deforms essentially by dislocation creep with dominant [100] slip. The resulting crystal preferred orientation has been used extensively to explain the strong seismic anisotropy observed down to 250 km depth. The rapid decrease of anisotropy below this depth has been interpreted as marking the transition from dislocation to diffusion creep in the upper mantle. But new high-pressure experiments suggest that dislocation creep also dominates in the lower part of the upper mantle, but with a different slip direction. Here we show that this high-pressure dislocation creep produces crystal preferred orientations resulting in extremely low seismic anisotropy, consistent with seismological observations below 250 km depth. These results raise new questions about the mechanical state of the lower part of the upper mantle and its coupling with layers both above and below. PMID:15716950

Mainprice, David; Tommasi, Andréa; Couvy, Hélène; Cordier, Patrick; Frost, Daniel J

2005-02-17

94

X-ray absorption experiments on rare earth and uranium compounds under high pressure  

International Nuclear Information System (INIS)

After an introduction into the phenomenon of the mixed valency and the method of measuring the microstructures by X-ray absorption spectroscopy in the area of the L edges under pressure, the results of investigations at selected substitutes of the chalcogenides and puictides of the rare earths and the uranium were given. Thus, pressure-induced valency transitions in YbS and YbTe, instabilities in valency and structural phase transitions in EUS and SmTe as well as the change in the electron structure in USb under pressure were investigated in order to answer questions of solid state physics (e.g. semiconductor-metal transitions, correlation between valency and structural phase transitions). Hybridization effects in LIII spectra of formally tetravalent Ca are analyzed at CeF4 and CeO2 (insulators) and the role of final state effects in the LIII spectra are analyzed at EuP2P2 and TmSe-TmTe (semiconductor systems). (RB)

95

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

96

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 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.

97

Energy balance in the solar transition region. II - Effects of pressure and energy input on hydrostatic models  

Science.gov (United States)

The radiation of energy by hydrogen lines and continua in hydrostatic energy-balance models of the transition region between the solar chromosphere and corona is studied using models which assume that mechanical or magnetic energy is dissipated in the hot corona and is then transported toward the chromosphere down the steep temperature gradient of the transition region. These models explain the average quiet sun and also the entire range of variability of the Ly-alpha lines. The relations between the downward energy flux, the pressure of the transition region, and the different hydrogen emission are described.

Fontenla, J. M.; Avrett, E. H.; Loeser, R.

1991-01-01

98

Towards the bulk carbon content of Earth; new metal carbide geobarometer in high pressure diamond.  

Science.gov (United States)

Formation of the metallic core in Earth (and other terrestrial planets) is not thought to have completely removed metallic iron from the lower mantle, where metallic iron might therefore be expected to occur as a widespread minor component [1]. We provide a new interpretation of metallic carbide inclusions in some diamond, which support a very high pressure origin from the lower mantle. Unlike rare carbides reported from diamonds previously without silicon [2], some diamonds from Jagersfontein coexist with iron-rich carbides which do contain significant silicon and oxygen, including in some cases their partial exsolution products. Based on an experimental calibration for liquid iron coexisting with lower mantle perovskite [3], we are able to show that some carbides were likely derived from pressures of approximately 45 GPa, or depths of >1100 km. This potential geobarometer has not been corrected for the behaviour of carbon in the liquid iron system, which might be an important experimental goal. The recognition of this independent carbide geobarometer offers an important new tool to confirm the superdeep origin of some diamond. The carbide-bearing diamonds are from a group whose charcteristics have recently been described [5]. Their distinctive light carbon isotopic signature (13^C ~ 17 ) coupled with evidence for very low contents nitrogen which is nonetheless highly aggregated, might be interpreted as indicative of subducted carbon. However, we are also open to the possibility that the bulk carbon isotopic composition of the Earth might also be different from the normal mantle value (13^C ~ 6 ), in which case the potential 0.4 wt% C in the Earth's core could also be isotopically very light, as suggested by Grady et al [6]. References [1] Frost D et al, Nature 428, 409-412 (2004) [2] Jacob D E et al, Contrib. Mineral. Petrol., 146, 566-576 (2004) [3] Lin et al, Science, 295, 313-315 (2002) [4] Dubrovinsky L. et al, Nature 422, 58-61 (2003) [5] Jones A P et al, 9th Int Kimb Conf 9IKC-A-00360 (2008) [6] Grady et al, Int. J. Astrobiol. 3, 117-124 (2004)

Jones, A. P.; Dobson, D.; Milledge, H. J.

2009-04-01

99

A well-balanced scheme for a one-pressure model of two-phase flows  

Energy Technology Data Exchange (ETDEWEB)

We consider a model of two-phase flows in which one phase is compressible and the other is incompressible. The system is a closed system with four governing equations for four unknowns. We construct a well-balanced scheme for this system. We then supplement the scheme with a practical modification so that it is always well defined. Our scheme is shown to be capable of maintaining equilibrium states.

Mai Duc Thanh [Department of Mathematics, International University, Quarter 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City (Viet Nam); Ismail, Ahmad Izani Md [School of Mathematical Sciences, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia)], E-mail: mdthanh@hcmiu.edu.vn, E-mail: izani@cs.usm.my

2009-06-15

100

Earth  

Science.gov (United States)

This NASA (National Aeronautics and Space Administration) planet profile provides data and images of the planet Earth. These data include planet size, orbit facts, distance from the Sun, rotation and revolution times, temperature, atmospheric composition, density, surface materials and albedo. Images with descriptions show Earth features such as the Ross Ice Shelf in Antarctica, Simpson Desert in Australia, Mt. Etna in Sicily, the Cassiar Mountains in Canada, the Strait of Gibraltar, Mississippi River, Grand Canyon, Wadi Kufra Oasis in Libya, and Moon images such as Hadley Rille, Plum Crater, massifs and Moon rocks. These images were taken with the Galileo Spacecraft and by the Apollo missions.

 
 
 
 
101

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

102

Observing Infrasound and Atmospheric Pressure with the NSF EarthScope USArray Transportable Array  

Science.gov (United States)

We are creating a real-time infrasound array whose sensing elements are co-located with the 400 seismic stations in the USArray Transportable Array component of the NSF EarthScope program. This continuously sampled array, of an unprecedented scale, will provide opportunities for groundbreaking and interdisciplinary research in atmospheric acoustics, atmospheric science, and seismology. Such an array will sample mean (absolute) values and fluctuations of the surface air pressure with nominal 70 km station spacing, with a dynamic range of about 7 orders of magnitude, and with a sampling frequency of up to 40 Hz. All samples will be synchronized to UTC. This dense network of infrasound sensors will permit us to study the nature of long-range infrasound propagation from regional to continental distances, and study the sources of infrasound signals, using actual acoustic data, free of concerns about seismic-to-acoustic coupling. All new TA stations deployed starting this fall will have a Quanterra Environmental Processor with internal VTI SCP1000 MEMS barometric pressure gauge, Setra 278 absolute microbarometer, and NCPA Infrasound Microphone. We will present data from field tests and from the newly deployed instrumentation.

Vernon, F. L.; Hedlin, M. A.; Busby, R. W.; Woodward, R.

2010-12-01

103

The "systolic volume balance" method for the noninvasive estimation of cardiac output based on pressure wave analysis.  

Science.gov (United States)

Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific conditions. A new systolic volume balance (SVB) method, including a simpler empirical form (eSVB), was derived from basic physical principles that govern blood flow and, in particular, a volume balance approach for the conservation of mass ejected into and flowed out of the arterial system during systole. The formulas were validated by a one-dimensional model of the systemic arterial tree. Comparisons of CO estimates between the proposed and previous methods were performed in terms of agreement and accuracy using "real" CO values of the model as a reference. Five hundred and seven different hemodynamic cases were simulated by altering cardiac period, arterial compliance, and resistance. CO could be accurately estimated by the SVB method as follows: CO = C × PP(ao)/(T - P(sm) × T(s)/P(m)) and by the eSVB method as follows: CO = k × C × PP(ao)/T, where C is arterial compliance, PP(ao) is aortic pulse pressure, T is cardiac period, P(sm) is mean systolic pressure, T(s) is systolic duration, P(m) is mean pressure, and k is an empirical coefficient. SVB applied on aortic pressure waves did not require calibration or empirical correction for CO estimation. An empirical coefficient was necessary for brachial pressure wave analysis. The difference of SVB-derived CO from model CO (for brachial waves) was 0.042 ± 0.341 l/min, and the limits of agreement were -0.7 to 0.6 l/min, indicating high accuracy. The intraclass correlation coefficient and root mean square error between estimated and "real" CO were 0.861 and 0.041 l/min, respectively, indicating very good accuracy. eSVB also provided accurate estimation of CO. An in vivo validation study of the proposed methods remains to be conducted. PMID:22427512

Papaioannou, Theodore G; Vardoulis, Orestis; Stergiopulos, Nikos

2012-05-15

104

Measuring Center of Pressure Signals to Quantify Human Balance Using Multivariate Multiscale Entropy by Designing a Force Platform  

Directory of Open Access Journals (Sweden)

Full Text Available To assess the improvement of human body balance, a low cost and portable measuring device of center of pressure (COP, known as center of pressure and complexity monitoring system (CPCMS, has been developed for data logging and analysis. In order to prove that the system can estimate the different magnitude of different sways in comparison with the commercial Advanced Mechanical Technology Incorporation (AMTI system, four sway tests have been developed (i.e., eyes open, eyes closed, eyes open with water pad, and eyes closed with water pad to produce different sway displacements. Firstly, static and dynamic tests were conducted to investigate the feasibility of the system. Then, correlation tests of the CPCMS and AMTI systems have been compared with four sway tests. The results are within the acceptable range. Furthermore, multivariate empirical mode decomposition (MEMD and enhanced multivariate multiscale entropy (MMSE analysis methods have been used to analyze COP data reported by the CPCMS and compare it with the AMTI system. The improvements of the CPCMS are 35% to 70% (open eyes test and 60% to 70% (eyes closed test with and without water pad. The AMTI system has shown an improvement of 40% to 80% (open eyes test and 65% to 75% (closed eyes test. The results indicate that the CPCMS system can achieve similar results to the commercial product so it can determine the balance.

Cheng-Wei Huang

2013-08-01

105

Stochastic water balance simulation for Lake Balaton (Hungary) under climatic pressure.  

Science.gov (United States)

Lake Balaton--due to its remarkable shallowness--is deemed to be sensitive to climatic variations. Historical records suggest, that the water level naturally fluctuated within significantly broader boundaries than the present regulation interval. We made a detailed, dynamic water balance simulations relying on a watershed model and two climatic scenarios. A periodic ARMA model simulated the natural water balance of the lake. The results confirmed, that the lake is not endangered under the expected climate changes. The probability of low levels may increase in the future by up to an order of magnitude. Uneven distribution and increased deviation of precipitation was found to be an important climatic factor from the aspect of low waters. A sensitivity analysis showed, that the sensitivity of the lake increases with the amplitude of climate change. The parameter uncertainty analysis revealed, that even with so long history of observations, the uncertainty of statistical estimates has larger effect than the anticipated climate change. Unfortunately, the time horizon of climate change is not far enough to make up for the necessary data collection, so possible interventions must dispense with a sound scientific justification. PMID:19213999

Honti, M; Somlyódy, L

2009-01-01

106

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

107

Sodium-potassium balance in the regulation of high blood pressure  

Directory of Open Access Journals (Sweden)

Full Text Available The World Health Organization considers essential hypertension as a primary cause of death. Twenty-five percent of the population over 15 has high blood pressure (HBP, equivalent to a billion people. It has been predicted that this group will increase by 60%, lineal with age increase in the overall population. Unfortunately, detection, treatment and effective control of HBP, are deficient both in Chile and in the rest of the world, making it an unresolved health problem demanding urgent attention. The recently conducted Chilean National Health Survey (2009-2010 revealed a 26.9% prevalence of this condition in the population, sixty-five percent of individuals are aware of their condition, 37.6% are in treatment and only 16,49% are effectively controlled. Furthermore, the survey reveals unhealthy life-style markers, which explains the epidemic that besets the country as there are multiple risk factors at stake. This review focuses mainly on the importance of the sodium-potassium relationship in the regulation of high blood pressure. It must be pointed out that all of the studies underscore the importance of sodium in the genesis of hypertension because of its effects of blood pressure, especially in sensitive individuals, while little attention has been given to the manifold beneficial actions of potassium in the regulation of blood pressure.

Luis Hernán Zárate Méndez

2012-02-01

108

Electron spin transition causing structure transformations of earth's interiors under high pressure  

Science.gov (United States)

To elucidate the correlation between structure transitions and spin state is one of the crucial problems for understanding the geophysical properties of earth interiors under high pressure. High-pressure studies of iron bearing spinels attract extensive attention in order to understand strong electronic correlation such as the charge transfer, electron hopping, electron high-low spin transition, Jahn-Teller distortion and charge disproponation in the lower mantle or subduction zone [1]. Experiment Structure transitions of Fe3-xSixO4, Fe3-xTixO4 Fe3-xCrxO4 spinel solid solution have been investigated at high pressure up to 60 GPa by single crystal and powder diffraction studies using synchrotron radiation with diamond anvil cell. X-ray emission experiment (XES) at high pressure proved the spin transition of Fe-K? from high spin (HS) to intermediate spin state (IS) or low spin state (LS). Mössbauer experiment and Raman spectra study have been also conducted for deformation analysis of Fe site and confirmation of the configuration change of Fe atoms. Jahn-Teller effect A cubic-to-tetragonal transition under pressure was induced by Jahn-Teller effect of IVFe2+ (3d6) in the tetrahedral site of Fe2TiO4 and FeCr2O4, providing the transformation from 43m (Td) to 42m (D2d). Tetragonal phase is formed by the degeneracy of e orbital of Fe2+ ion. Their c/a ratios are c/aion [2]. Spin transition HS-to-LS transition starts from 15.6GPa in Fe3O4, 19.6 GPa in Fe2TiO4, 17GPa in Fe2SiO4. The transition is more capable due to VIFe2+ in the octahedral site. The extremely shortened octahedral bonds result in a distortion of 8-fold cation site. This structure change is accelerated by HS-LS transition of Fe2+ in the 8-fold coordination site. Post spinel transition The transition to orthorhombic post-spinel structure with Cmcm has been confirmed in the whole compositional range of Fe3-xTixO4 and Fe3-xCrxO4 . There are M1 and M2 in the orthorhombic phase. Fe2+ and Ti4+ are disordered in the M2 site. At pressures above 53 GPa, Fe2TiO4 structure further transforms to Pmma. This structure change results in the order-disorder transition [2]. New structure of Fe2SiO4 The spin transition exerts an influence to Fe2SiO4 spinel structure and triggers two distinct curves of the lattice constant in the spinel phase. The reversible structure transition from cubic to pseudo-rhombohedral phase was observed at about 45 GPa. This transition is induced by the 20% shrinkage of ionic radius of VIFe2+at the low sin state. Laser heating experiment at 1500 K has confirmed the decomposition from the pseudo-rhombohedral phase to two oxides of FeO and SiO2. [1] T. Yamanaka High-Pressure research 28, 203-216 (2008) [2] T. Yamanaka, T. Mine, S. Asogawa and Y. Nakamoto Physical Review B 80, 134120 (2009)

Yamanaka, T.; Kyono, A.; Kharlamova, S.; Alp, E.; Bi, W.; Mao, H.

2012-12-01

109

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

110

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

International Nuclear Information System (INIS)

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)

111

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

112

Highly balanced single-layer high-temperature superconductor SQUID gradiometer freely movable within the Earth's magnetic field  

Energy Technology Data Exchange (ETDEWEB)

We developed a gradiometer system based on a single-layer high-temperature superconductor dc superconducting quantum interference device (SQUID), which can be freely moved within the Earth's magnetic field during measurement. The problem of circumferential shielding currents in the parallel gradiometer pick-up loop is solved by the use of an appropriately designed magnetometer SQUID integrated on the gradiometer chip. The magnetometer's feedback coil of the flux-locked loop is laid out as a small Helmholtz coil pair, thus keeping the homogeneous magnetic field constant for both the magnetometer and the gradiometer. Therefore, the balance of the directly coupled gradiometer SQUID is enhanced from 100 up to 3800. The noise limited magnetic field gradient resolution of 45 pT m{sup -1} Hz{sup -1/2} is preserved down to frequencies of several Hz even after strong motion in the Earth's magnetic field.

Schultze, Volkmar; IJsselsteijn, Rob; May, Torsten; Meyer, Hans-Georg [Department of Quantum Electronics, Institute for Physical High Technology, D-07745 Jena (Germany)

2003-07-01

113

Band structures of CsCl-structured BaS and CaSe at high pressure: Implications for metallization pressures of the alkaline earth chalcogenides  

Science.gov (United States)

The indirect energy gaps of CsCl-structured BaS and CaSe are measured at high pressures using absorption spectroscopy to pressures of 41 and 53 GPa, respectively. Band-structure calculations using density-functional theory and quasiparticle corrections are also conducted on BaS and CaSe as a function of pressure. The measured indirect gaps of BaS and CaSe shift linearly with pressure with a slope, (dEgap/dP), of -1.8(2)×10-2 and -1.5(3)×10-2 eV/GPa, respectively. These values are in reasonable agreement with the theoretical results of -2.2×10-2 eV/GPa for BaS and -2.3×10-2 eV/GPa for CaSe. Our calculations indicate that the energy gap in both compounds is indirect with the valence-band maxima at M and the conduction-band minima at ?. Based on a simple linear extrapolation of our data, we estimate the metallization pressures of CsCl-structured BaS and CaSe to be above 113 and 125 GPa, respectively. Our estimates of metallization pressures are compared with those of other alkaline earth monochalcogenides to determine the degree to which changes in the electronic structures of these compounds under pressure can be described using systematic trends based on ionic radii.

Cervantes, Phillip; Williams, Quentin; Côté, Michel; Rohlfing, Michael; Cohen, Marvin L.; Louie, Steven G.

1998-10-01

114

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

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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

115

Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure  

Science.gov (United States)

Supine hypertension, which is very common in patients with autonomic failure, limits the use of pressor agents and induces nighttime natriuresis. In 13 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nifedipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supine BP, renal sodium handling, and orthostatic tolerance was determined. Medications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin was removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin decreased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P hypertension in patients with autonomic failure. However, nifedipine has a prolonged depressor effect and worsens orthostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with nitroglycerin and nifedipine may be offset by a direct effect of both drugs on renal sodium handling.

Jordan, J.; Shannon, J. R.; Pohar, B.; Paranjape, S. Y.; Robertson, D.; Robertson, R. M.; Biaggioni, I.

1999-01-01

116

Tracking Severe Thunderstorm Outflows and Local Pressure Changes Using NSF EarthScope USArray TA Pressure Sensors  

Science.gov (United States)

The NSF Earthscope USArray Transportable Array, a dense array of over 400 seismic stations deployed in a grid with 75km station spacing, provides real-time monitoring of seismicity as well as surface barometric pressure from instrumentation housed within enclosed vaults. Beginning on June 22nd 2010 several of the stations from North Dakota south through Texas have periodically observed sudden and dramatic increases in surface pressure (ranging from ~2.0 to 4.0 mb in less than 5 minutes, sometimes with gradual increases following). Doppler radar, local observations and satellite images confirm the passage of moderate to severe thunderstorms coinciding with these pressure jumps. On further investigation, it was determined that the USArray TA stations observing the pressure jumps were actually observing outflow gust fronts from the thunderstorms on multiple occasions throughout the summer months. Additional pressure observations reveal the effects of dense, sinking air associated with evaporative cooling in the downdraft regions of some of the more severe thunderstorms. The data presented within this paper will reveal the temporal nature and speed of these characteristics using the high-resolution continuous 1sps pressure data from several USArray TA stations. Additional data will be provided from Doppler radar and satellite images as well as local observations. The overall utility and viability of the USArray TA pressure data will then be discussed as a supplemental aid for now-casting severe weather events.

Tytell, J. E.; Vernon, F. L.; Eakins, J. A.

2010-12-01

117

The elastic constants of MgSiO3 perovskite at pressures and temperatures of the Earth's mantle  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The temperature anomalies in the Earth's mantle associated with thermal convection1 can be inferred from seismic tomography, provided that the elastic properties of mantle minerals are known as a function of temperature at mantle pressures. At present, however, such information is difficult to obtain directly through laboratory experiments. We have therefore taken advantage of recent advances in computer technology, and have performed finite-temperature ab initio molecular d...

Oganov, A. R.; Brodholt, J. P.; Price, G. D.

2009-01-01

118

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

119

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

120

Studies on the high-pressure reaction of rare-earth sesquioxides with vanadium dioxide  

International Nuclear Information System (INIS)

The reaction of rare-earth sesquioxides (Ln2O3) with vanadium dioxide (VO2) at 1400sup(o)C and 50 kbar* * and 30 kbar was studied. Quadrivalent vanadium ions were reduced to the trivalent state, rare-earth vanadates (III) (LnVO3) being obtained. For LnVO3 a typical transformation of the ABO3-type compounds, one from the aragonite-type to the perovskite-type via the vaterie- or calcite-type structure was observed with a decrease in the ionic radius of the rare-earth ions. The magnetic properties of the vaterite-type LnVO3 were studied. (author)

 
 
 
 
121

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

122

High pressure transport measurements on the rare earth systems samarium hexaboride, cerium bismuth platinide and europium hexaboride  

Science.gov (United States)

High pressure transport and magnetotransport measurements on the rare earth systems SmB6,/ Ce3Bi4Pt3 and EuB6 as well as high pressure magnetic measurements on EuB6 are reported. In the case of SmB6 the resistivity, magnetoresistance and Hall effect were measured at pressures to 150 kbar, and fields as high as 18 T, over temperatures from 1 K to 300 K. At 1 bar SmB6 is a metal with a resistivity well in excess of the unitarity limit at low temperature. The mean field hybridization model used for Kondo Insulators cannot explain the sudden collapse of the gap in this material at a sample dependent critical pressure or the gap's weak quadratic field dependence. At high pressure the resistivity of SmB6 resembles that of a non ordering heavy fermion material with a T2 temperature dependence. The field dependence of the high pressure resistivity suggests a Fermi surface orbit shaped similarly to one in LaB6. The resistivity of the Kondo Insulator Ce3Bi4Pt3 was measured at pressures up to 150 kbar at temperatures between 1 K and 300 K. The gap ? increases by an order of magnitude in this pressure range. From ?, the pressure dependences of the Kondo temperature and Ce valence were determined and found consistent with the predictions of the mean field hybridization model in the weak coupling limit. Three dimensional variable range hopping was found to dominate the low temperature transport at pressures above 30 kbar. In EuB6 the resistivity and magnetoresistance were measured at pressures from 1 bar to 169 kbar in fields to 7 T over temperatures from 1 K to 300 K. The magnetoresistance near the ordering temperature TC is negative and scales with the magnetization while at low temperature it is large, ?rho/?0 > 10, and positive. Shubnikov-de Haas oscillations about a small branch of the Fermi surface were observed. In addition TC was measured using a magnetic susceptibility technique at pressures from 1 bar to 57 kbar. The apparatus is described. Tc increases with pressures up to ~100 kbar, then becomes nearly pressure independent. Finally evidence of an unusual two step magnetic ordering process was found in the temperature dependence of the spontaneous magnetization and resistivity.

Cooley, Jason Christopher

1997-11-01

123

The Effect of Nickel on the Seismic Wave Belocities of Iron at the Pressure Conditions of the Earth's Core  

Science.gov (United States)

Understanding the physical properties of the Earth's core is a key step in the study of the evolution and dynamics of our planet. For much of the last century, based on studies of meteorites [1], it was believed that Earth's core was predominantly a mixture of iron and nickel. More specifically, the Earth's inner core is a solid Fe-Ni alloy at high temperature (T, 6000 K) and high pressure (P, 360 GPa). Furthermore, to account for the lower than expected density in the Earth's core, it has been suggested that light elements must also be present [2]. While the effect of light elements on the properties of iron have been the subject of an extensive literature [3-6], the effect of nickel on the properties of iron has often been overlooked; this is due to the expectation, based on their proximity in the periodic table, that the properties of Ni are sufficiently similar to those of iron that the presence of nickel can be neglected. Although recent research using high P-T experiments and theoretical studies of Fe-Ni alloys has been performed in order to establish whether nickel affects the physical properties of iron, the results have been inconclusive and sometimes contradictory [7-11]. Here we present a DFT study of the athermal elastic properties of solid Fe-Ni alloys at core pressures using the GGA. We have calculated the equation of state (EoS) for Fe-Ni alloys at several compositions for bcc, fcc and hcp structures, and fitted the results to Birch-Murnaghan 3rd order equations of state. We have also calculated the elastic constants for each structure at 360 GPa and evaluated the seismic wave velocities. Our results show that the effect of small amounts of Ni is significant (-1.9% in vp and -4.0% in vs for hcp structure of Fe93.25-Ni6.75 alloy), and therefore nickel must be taken into account if a detailed model of the Earth's inner core is to be constructed. Other aspects of the influence of nickel, such as its effect on the high P-T phase diagram and melting curve, have yet to be conclusively established. 1. McDonough, Sun, Chem Geol 120 (1995) 223 2. Poirier, Phys Earth Planet Int 85 (1994) 319 3. Côté, Vo?adlo, Dobson, Alfè, Brodholt, Phys Earth Planet Int 178 (2010) 2 4. Shahar, Xiegler, Young, Ricolleau, Schauble, Fei, Earth Planet Scie Lett 288 (2009) 228 5. Lin, Scott, Fischer, Chang, Kantor, Prakapenka, Geophys Res Lett 36 (2009) 6306 6. Côté, Vo?adlo, Brodholt, Geophys Res Lett 35 (2008) 5306 7. Kuwayama, Hirose, Stat, Ohishi, Earth Planet Scie Let 273 (2008) 379 8. Shabashov, Zamatovskii, Pilyugin, Phys. Met Metallogr+ 108 (2009) 475 9. Erkholm, Mikhaylushkin, Simak, Johansson, Abrikosov, Earth Planet Sci Lett 308 (2011) 90 10. Kantor, Kantor, Kurnosov, Kuznetsov, Dubrovinskaia, et al., Phys Earth Planet Int 164 (2007) 83 11. Asker, Vitos, Abrikosov, Phys. Rev B 79 (2009) 214112

Martorell Masip, B.; Vocadlo, L.; Brodholt, J. P.; Wood, I.

2011-12-01

124

Dynamic balance improvement program  

Science.gov (United States)

The reduction of residual unbalance in the space shuttle main engine (SSME) high pressure turbopump rotors was addressed. Elastic rotor response to unbalance and balancing requirements, multiplane and in housing balancing, and balance related rotor design considerations were assessed. Recommendations are made for near term improvement of the SSME balancing and for future study and development efforts.

Butner, M. F.

1983-01-01

125

Anomalous thermal expansion and magnetostriction of rare earth compounds under high pressure  

International Nuclear Information System (INIS)

The thermal expansion coefficients of Kondo compounds, CeBe13 and CeRh2Si2, and the magnetostriction of Tb0.3Dy0.7Fe2(Terfenol-D) have been measured at high pressure. By simple analysis using thermodynamical relation, it is found that the density of state at the Fermi level and the Gruneisen parameters ? of the Kondo compounds decrease rapidly with increasing pressure corresponding to the large pressure-induced enhancement of Kondo temperatures. An anomalous behaviour in the thermal expansion coefficients of CeRh2Si2 is observed at high pressure above TN. This anomaly is suggested as an origin of pressure-induced superconductivity. The giant magnetostriction (GMS) of Terfenol-D is found to be enhanced by applying hydrostatic pressure below 0.5-bar GPa but GMS decreases above it. These results are discussed briefly by comparing with the previous ones

126

BLOOD PRESSURE, HEART RATE AND MELATONIN CYCLES SYNCHRONIZATION WITH THE SEASON, EARTH MAGNETISM AND SOLAR FLARES.  

Science.gov (United States)

Three spectral components with periods of about (~) 0.41, ~0.5 and ~1.0 year had been found with serially independent sampling in human circulating melatonin. The time series consisted of around-the-clock samples collected for 24 hours at 4-hour intervals from different patients over several years. Some of these components had been found to be circadian stage-dependent, the daytime measurements following mostly a circannual variation, whereas a half-year characterized the nighttime samples. The latter were incorporated into a circasemiannual map. The relative brevity of the series prevented a check for the coexistence of all three spectral components, even if each component seemed to have a raison d'être. In time series of transdisciplinary data, a 1.00-year synchronized component is interpreted as representing the seasons. The half-year may qualify the circannual waveform, but it is also a signature of geomagnetics. An ~0.41-year (~5-month) component is the signature of solar flares. It has been called a cis-half-year (cis = on this side of a half-year) and may be detected only intermittently. Charles L. Wolff predicted the existence, among others, of ~0.42- and ~0.56-year components as beat periods of rotations at different solar latitudes.The multiple components characterizing circulating melatonin could also be found in a (to our knowledge unique) data set of a clinically healthy scientist (RBS). Herein, we focus on vascular data self-measured by RBS as he aged from ~20 to ~60 years. A multi-component model consisting of cosine curves with periods of 0.41, 0.50 and 1.00 year was fitted to weekly means of systolic (S) and diastolic (D) blood pressure (BP) and heart rate (HR) collected ~5 times a day over 39 years by RBS. All three components can coexist for a while, although all of them are nonstationary in their characteristics and come and go by the criterion of statistical significance.Intermittently, BP and HR are synchronized selectively with one or the other aspect of RBS' physical environment, namely the seasons (at ~1.0 year), earth magnetism (at ~0.5 year) and/or solar flares (at ~0.42 year). Cosmic-biotic transfer of information, albeit hardly of energy (the biospheric amplitudes are very small) may be mediated in this set of frequency windows. As found earlier, RBS' circulation is also frequency-trapped environmentally in multidecadal windows, HR being locked into the transtridecadal Brückner, or rather Brückner-Egeson-Lockyer, BEL sunspot and terrestrial weather cycle, while his BP follows Hale's didecadal cycle in the changing polarity of sunspots.The ~0.41-year HR cycle may be associated with changes in solar flares, the cis-half-year amplitude of HR showing a cross-correlation coefficient of 0.79 with the total solar flare index (from both solar hemispheres) at a lag of ~3.2 years. The superposed time courses of these two variables indicate the presence of a shared Horrebow-Arago-Schwabe sunspot cycle of ~11 years, the cis-half-year in HR being more prominent after the total solar flare index reaches its ~11-year peak. Differences in the time-varying behavior of BP vs. HR are also described. PMID:21566725

Cornélissen, G; Halberg, F; Sothern, R B; Hillman, D C; Siegelová, J

2010-01-01

127

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

Science.gov (United States)

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 cu m volume of rock increased by 1470 cu m. The corresponding increase in fluid storage between 7.5 and 15 MPa was 1090 cu m. 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, Donald W.; Robinson, Bruce A.

128

From Science Reserves to Sustainable Multiple Uses beyond Earth orbit: Evaluating Issues on the Path towards Balanced Environmental Management on Planetary Bodies  

Science.gov (United States)

Over the past five decades, our understanding of space beyond Earth orbit has been shaped by a succession of mainly robotic missions whose technologies have enabled scientists to answer diverse science questions about celestial bodies across the solar system. For all that time, exploration has been guided by planetary protection policies and principles promulgated by COSPAR and based on provisions in Article IX of the Outer Space Treaty of 1967. Over time, implementation of the various COSPAR planetary protection policies have sought to avoid harmful forward and backward contamination in order to ensure the integrity of science findings, guide activities on different celestial bodies, and appropriately protect Earth whenever extraterrestrial materials have been returned. The recent increased interest in extending both human missions and commercial activities beyond Earth orbit have prompted discussions in various quarters about the need for updating policies and guidelines to ensure responsible, balanced space exploration and use by all parties, regardless whether activities are undertaken by governmental or non-governmental entities. Already, numerous researchers and workgroups have suggested a range of different ways to manage activities on celestial environments (e.g, wilderness parks, exclusion zones, special regions, claims, national research bases, environmental impact assessments, etc.). While the suggestions are useful in thinking about how to manage future space activities, they are not based on any systematically applied or commonly accepted criteria (scientific or otherwise). In addition, they are borrowed from terrestrial approaches for environmental protection, which may or may not have direct applications to space environments. As noted in a recent COSPAR-PEX workshop (GWU 2012), there are no clear definitions of issues such as harmful contamination, the environment to be protected, or what are considered reasonable activity or impacts for particular locations—and over what time frames. Likewise, there are no guidelines for how to deal with the potential conflict between economic viability for commercial space activity and the need for reasonable planetary protection measures and standards. Before creating guidelines for particular locations or developing a international environmental regime for blending space exploration and use, it is advisable to have at least have a cursory overview of what lies ahead in the technical, scientific, commercial, environmental and policy realms. To develop such an overview, I undertook a preliminary analysis of the proposed activities, stakeholders, timeframes, and potential environmental impacts anticipated in coming years for robotic and human missions, particularly for the Moon and Mars. Hopefully, this type of information will be useful as the international community works towards updating policies and guidelines for responsible, balanced space exploration and use by all parties.

Race, Margaret

129

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

130

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).

131

Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride  

Energy Technology Data Exchange (ETDEWEB)

We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing lattice constant across the rare-earth series. We propose a possible mechanism describing this behavior and we suggest the presence of a one-dimensional character in these two-dimensional compounds. We also envisage that interactions and umklapp processes might play a relevant role in the formation of the charge-density-wave state in these compounds.

Sacchetti, A.; Degiorgi, L.; /Zurich, ETH; Giamarchi, T.; /Geneva U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.

2009-12-14

132

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.)

133

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

134

The effect of temperature and pressure on the elastic behaviour of rare-earth phosphate glasses  

International Nuclear Information System (INIS)

The longitudinal and shear wave velocities propagated in phosphate glasses containing samarium, euporium, neodynium and lantanum have been studied for the first time using the ultrasonic technique from 4.2 to 300 K. The elastic behaviour changes with temperature in an anomalous fashion due to anharmonic vibrational, thermally activated relaxations and the present of two-level system especially at low temperature. The pressure variation of the elastic constants has also been measured and has been used to calculate the elastic Grueneisen parameter for these glasses. For each of these vitreous materials, except the lanthanum phosphates, the bulk and shear moduli decrease under hydrostatic pressure; an indication of acoustic modes softening

135

Earth in the balance. Ecology and the human spirit; Urgence Planete Terre. L'esprit humain face a la crise ecologique  

Energy Technology Data Exchange (ETDEWEB)

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 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.

Al Gore

2007-07-01

136

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

Science.gov (United States)

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.

Pandey, Sugandha Dogra; Samanta, K.; Singh, Jasveer; Sharma, Nita Dilawar; Bandyopadhyay, A. K.

2014-10-01

137

Device for achieving pressure balance in the steam generator of a power plant in case of a main-steam pipe or a feedwater pipe break  

International Nuclear Information System (INIS)

In order to increase the safety in the steam generator of a power plant in case of a pipe break, the possibility of a pressure balance between the feedwater inlet and the initial steam outlet chambers is allowed for. According to the invention, the partition wall separating these two chambers will exhibit several overflow openings, each of which will be provided with a closure and half of which may be opened to one side only, care having been taken that in case of an accident on occurrence of a certain differential pressure they will always be opened to the low-pressure side. As closures caps, which may be swing out of the way, or rupture diaphragms are mentioned. (UWI) 891 HP

138

Experimental study on thermal-hydraulic behaviors of a pressure balanced coolant injection system for a passive safety light water reactor JPSR  

Energy Technology Data Exchange (ETDEWEB)

A conceptual design study of a passive safety light water reactor JPSR has been performed at Japan Atomic Energy Research Institute JAERI. A pressure balanced coolant injection experiment has been carried out, with an objective to understand thermal-hydraulic characteristics of a passive coolant injection system which has been considered to be adopted to JPSR. This report summarizes experimental results and data recorded in experiment run performed in FY. 1993 and 1994. Preliminary experiments previously performed are also briefly described. As the results of the experiment, it was found that an initiation of coolant injection was delayed with increase in a subcooling in the pressure balance line. By inserting a separation device which divides the inside of core make-up tank (CMT) into several small compartments, a diffusion of a high temperature region formed just under the water surface was restrained and then a steam condensation was suppressed. A time interval from an uncovery of the pressure balance line to the initiation of the coolant injection was not related by a linear function with a discharge flow rate simulating a loss-of-coolant accident (LOCA) condition. The coolant was injected intermittently by actuation of a trial fabricated passive valve actuated by pressure difference for the present experiment. It was also found that the trial passive valve had difficulties in setting an actuation set point and vibrations noises and some fraction of the coolant was remained in CMT without effective use. A modification was proposed for resolving these problems by introducing an anti-closing mechanism. (author)

Satoh, Takashi; Watanabe, Hironori; Araya, Fumimasa; Nakajima, Katsutoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwamura, Takamichi; Murao, Yoshio

1998-02-01

139

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 desbalance 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.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-tubule 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

2010-12-01

140

Experimental study on thermal-hydraulic behaviors of a pressure balanced coolant injection system for a passive safety light water reactor JPSR  

International Nuclear Information System (INIS)

A conceptual design study of a passive safety light water reactor JPSR has been performed at Japan Atomic Energy Research Institute JAERI. A pressure balanced coolant injection experiment has been carried out, with an objective to understand thermal-hydraulic characteristics of a passive coolant injection system which has been considered to be adopted to JPSR. This report summarizes experimental results and data recorded in experiment run performed in FY. 1993 and 1994. Preliminary experiments previously performed are also briefly described. As the results of the experiment, it was found that an initiation of coolant injection was delayed with increase in a subcooling in the pressure balance line. By inserting a separation device which divides the inside of core make-up tank (CMT) into several small compartments, a diffusion of a high temperature region formed just under the water surface was restrained and then a steam condensation was suppressed. A time interval from an uncovery of the pressure balance line to the initiation of the coolant injection was not related by a linear function with a discharge flow rate simulating a loss-of-coolant accident (LOCA) condition. The coolant was injected intermittently by actuation of a trial fabricated passive valve actuated by pressure difference for the present experiment. It was also found that the trial passive valve had difficulties in setting an actuation set point and vibrations noises and some fraction of the coolant was remained in CMT without effective use. A modification was proposed for resolving these problems by introducing an anti-closing mechanism. (author)

 
 
 
 
141

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.

142

Correlation between sway parameters of center of pressure in quiet standing with eyes open and eyes closed, functional balance tests and symmetry index in chronic hemiparesis patients  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background and Aim: Proprioceptive problems, visuospatial deficits and muscle weakness are the main causes of weight bearing asymmetry and postural control impairment in chronic hemiparesis patients. The aim of this study was to investigate the correlation between center of pressure parameters in quiet standing with eyes open and closed and functional balance tests and symmetry index in these patients. Materials and Methods: In this correlation study, 16 stroke patients (mean age: 52.937±10.109 years, were selected by simple non-probability sapling. Force plate, Functional Reach and Timed Up and Go tests and scales were used in order to investigate postural sway parameters in quiet standing, functional balance and symmetry index, respectively. Results: Moderate to high significant correlation was obtained between Timed Up and Go test and symmetry index and most of the postural sway parameters in eyes closed condition, while Functional Reach test had only moderate significant correlation with standard deviation of velocity (anterior-posterior and phase plane total. Also symmetry index showed moderate correlation with most of the postural sway parameters. Conclusion: Current study demonstrates the role of vision and task in correlation between center of pressure parameters, balance tests and symmetry index. Key words: Correlation, Symmetric weight bearing, Postural sway, Functional Reach, Timed Up and Go, Force plate, Quiet standing

Dorsa Hamedi

2013-11-01

143

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

144

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

145

Metal-silicate partitioning of iodine at high pressures and temperatures: Implications for the Earth's core and 129*Xe budgets  

Science.gov (United States)

The partition coefficients of iodine Dmet/sil between molten metal and molten silicate were investigated using a Laser Heated Diamond Anvil Cell (LHDAC) at pressures between 2 and 20 GPa and at ~2800 K. No pressure dependence of Dmet/sil was observed within this range, but the composition of the Fe-Ni alloy liquid phase was shown to have an effect. When the metallic liquid was alloyed with S, O and Si, there was an increase in iodine solubility in the metal. Iodine exhibited mildly siderophile behaviour across all the investigated conditions, with Dmet/sil=1.25±0.65 (2 s.d.) (Fe metal system) and Dmet/sil=4.33±1.41 (2 s.d.) (Fe-alloy). In conjunction with a revised bulk silicate Earth (BSE) concentration, it is calculated that the core could be a significant reservoir for iodine, with up to 82% of the bulk Earth's iodine budget in the core, depending on the light element content of the metal phase and the process of core formation. The composition of the metal phase appears to have a greater effect on the partitioning and sequestration of iodine than the style of core segregation. As the core likely formed while 129I was still extant, the core can also be a reservoir for radiogenic 129Xe from the decay system 129I-129Xe (T1/2=15.7 Myr). Preliminary modelling indicates that the decay of 129I in the core has the potential to generate radiogenic 129Xe concentrations that are at least two orders of magnitude greater than what has been estimated for the depleted mantle. While this may have a significant impact on the isotopic signatures of the overlying mantle, it is not yet clear how flux from the core fits within the overall picture of mantle noble gas evolution.

Armytage, Rosalind M. G.; Jephcoat, Andrew P.; Bouhifd, M. A.; Porcelli, Donald

2013-07-01

146

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

147

Windsock memory COnditioned RAM (CO-RAM) pressure effect: Forced reconnection in the Earth's magnetotail  

Science.gov (United States)

Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by Dungey (1963) can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its numerous modifications were able to explain fully the onset conditions for MR in the tail. In this paper, we introduce new onset conditions for forced MR in the tail. We call our scenario the "windsock memory conditioned ram pressure effect." Our nonflux transfer-associated forcing is introduced by a combination of the large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented interplanetary magnetic field (IMF). Using global MHD Grand Unified Magnetosphere Ionosphere Coupling Simulation version 4 simulation results, upstream data from Wind, magnetosheath data from Cluster 1 and distant tail data from the two-probe Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun mission, we show that the simultaneous occurrence of vertical windsock motions of the magnetotail and enhanced solar wind dynamic pressure introduces strong nightside disturbances, including enhanced electric fields and persistent vertical cross-tail shear flows. These perturbations, associated with a stream interaction region in the solar wind, drive MR in the tail during episodes of northward oriented interplanetary magnetic field (IMF). We detect MR indirectly, observing plasmoids in the tail and ground-based signatures of earthward moving fast flows. We also consider the application to solar system planets and close-in exoplanets, where the proposed scenario can elucidate some new aspects of solar/stellar wind-magnetosphere interactions.

Vörös, Z.; Facskó, G.; Khodachenko, M.; Honkonen, I.; Janhunen, P.; Palmroth, M.

2014-08-01

148

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

149

Windsock memory conditioned RAM (Co-Ram) pressure effect: forced reconnection in the Earth's magnetotail  

CERN Document Server

Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by \\citet{dung63}, can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its numerous modifications were able to explain fully the onset conditions for MR in the tail. In this paper, we introduce new onset conditions for forced MR in the tail. We call our scenario the "windsock memory conditioned ram pressure effect". Our non-flux-transfer associated forcing is introduced by a combination of large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented IMF. Using global MHD GUMICS-4 simulation results, upstream data from WIND, magnetosheath data from Cluster-1 and distant-tail data from the two-probe ARTEMIS mission, we show that the simultaneo...

Vörös, Z; Khodachenko, M; Honkonen, I; Janhunen, P; Palmroth, M

2014-01-01

150

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

151

Melting of Fe and Fe120Si8 at the Earth's Core Pressures by ab Initio Molecular Dynamics  

Science.gov (United States)

The solid Earth's inner core (IC) consists mainly of iron likely alloyed with some light elements. At low temperature iron is stable in hexagonal close packed (hcp) phase up to very high pressures. However, there is an accumulating evidence that under pressures (~ 364 GPa) and temperatures (above 6000 K) in the Earth's IC iron, either pure or alloyed with light elements (e.g. Si), might be stable in the body-centred cubic (bcc) phase1,2. The melting temperature of this phase in the IC is unknown. Conditions of the IC are not achieved in experiment. Previous theoretical studies concentrated mostly on the melting of the hcp phase3. We show, by combination of ab initio molecular dynamics and Z-method4 that pure bcc Fe melts at at the pressure in the center of IC at ~7000 K. Iron, alloyed with 6.25% of Si, melts at a temperature of ~7200 K. While light elements depress hcp Fe melting temperatures5, we show that Si addition has opposite effect on bcc Fe. Melting temperatures of bcc and hcp 2,3 are within mutual error bars, even though bcc melts at a higher temperature. However, the melting temperature of Si-alloyed bcc iron is clearly above that of Si-alloyed hcp phase5. This is because of different bonding of Si-Fe within the bcc as compared to the hcp structure. Therefore, the existing estimates of core temperatures have to be corrected upwards. 1. Brown, J.M. & McQueen, R.G. J. Geophys. Res. 91, 7485(1986). 2. Belonoshko, A.B., Ahuja, R. & Johansson, B. Nature 424, 1032(2003); Belonoshko, A.B., Skorodumova, N.V., Rosengren, A. & Johansson, B. Science 319, 797(2008). 3. Belonoshko, A.B., Ahuja, R. & Johansson, B. Phys. Rev. Lett. 84, 3638(2000); Alfé, D., Gillan, M.J. & Price, G.D. Nature 401, 462(1999). 4. Kresse, G. & Furthmüller, J. J. Phys. Rev. B 54, 11169(1996); Belonoshko, A.B., Skorodumova, N.V., Rosengren, A. & Johansson, B. Phys. Rev. B 73, 012201(2006). 5. Alfé, D., Price, G.D. & Gillan, M.J. Cont. Phys. 48, 63 (2007).

Belonoshko, A. B.; Rosengren, A.; Burakovsky, L.; Preston, D. L.; Johansson, B.

2008-12-01

152

The melting points of some rare-earth metal nitrides as a function of nitrogen pressure  

International Nuclear Information System (INIS)

The melting points of LaN, CeN, PrN, NdN, and GdN were determined in an autoclave in the pressure range 10-2 to 102 atm by means of the Pirani-Alterthum technique consisting of heating compact nitride rods until melting occurs. A narrow borehole extending to the centre of the rod served as the blackbody cavity. To check the results a second method was used in which a small amount of nitride powder was placed in the apex of a V-shaped tungsten ribbon and the ribbon was heated resistively until melting was observed. Although blackbody conditions were here absent, the results obtained by the two methods were in good agreement. The nitrides were subjected to X-ray and chemical analysis before and after melting. (author)

153

Application of a magnetic suspension balance to the oxidation study of the zirconium based alloys under high pressure water vapour  

International Nuclear Information System (INIS)

The fuel claddings in the Pressurised Water Reactor are corroded in water at high temperature and high pressure. The technical device able to follow continuously the corrosion rate in conditions close to this medium does not yet exist. That is the reason why a high pressure thermogravimetric installation based on magnetic suspension has been designed to study in situ the oxidation kinetics of the zirconium based alloys under water vapour until 50 bars of pressure at 415 degrees C. The accuracy of measurements is about 5 * 10-5 g under 2 bars, and 10-4 g under 50 bars. The reproducibility of measurements was verified and the deviation regarding post test weighing at room temperature is around 5 * 10-5 g what is clearly satisfying. Finally, the results presented in this work allow validating the high pressure thermogravimetric measurements obtained with this magnetic suspension device. (authors)

154

Estudio experimental del empuje sobre estructuras de contención en suelos reforzados con geomallas Experimental study of the lateral earth pressure on retaining structures in soils reinforced with geogrids  

Directory of Open Access Journals (Sweden)

Full Text Available Este artículo presenta un estudio experimental de la variación de las tensiones de empuje sobre una pared que soporta un suelo reforzado con geomallas. Para ello se utilizó un equipo diseñado y construido especialmente para ejecutar ensayos de empuje bajo condiciones de deformación plana. Se describe el equipo de ensayo y los instrumentos de medición, así como el suelo y la preparación de las muestras de arena y la geomalla utilizada. En la primera etapa de la investigación se ensayan muestras sin reforzar y se comparan los resultados con aquellos provenientes de las teorías clásicas de empuje. Posteriormente se presentan los resultados de ensayos de empuje en suelo reforzado con una, dos, tres y cuatro geomallas. Se concluye que la incorporación de geomallas como refuerzo en el suelo disminuye el empuje ejercido por el suelo sobre la estructura de contención. Esta disminución del empuje es de aproximadamente un 25% cuando se usa una geomalla, un 50% con dos o tres geomallas y de un 75% con cuatro geomallas para los espaciamientos, sobrecargas e incremento de desplazamientos usados. Resultó posible identificar que la distribución de la tensión de empuje con la profundidad no sólo no sigue la variación triangular sino que se desarrollan arcos de tensiones en el suelo entre las geomallas.This article presents an experimental study on the variation with depth of the stresses due to lateral earth pressure on a wall retaining a soil reinforced with geogrids. To this end, an apparatus was designed and constructed especially tailored for performing lateral earth pressure tests under plain strain conditions. The experimental apparatus and the measurement instruments as well as the soil and the sample preparation and the geogrids used, are described. In a first stage of research, samples without reinforcing are tested and the results are compared with those from classic earth pressure theories. Subsequently, results from lateral earth pressure tests in soils reinforced with one, two, three and four geogrids are presented. It is concluded that the inclusion of geogrids as soil reinforcement reduces the earth pressure on the retaining structure. This lateral earth pressure reduction is approximately of 25% when one geogrid is used, 50% with two or three geogrids and 75% with four geogrids for the spacing, surcharges and displacement increments used. It was possible to identify that the lateral earth pressure distribution with depth not only does not follow a triangular variation, but it develops stress arching in the soil and between the geogrids.

Lissette Ruiz-Tagle

2011-12-01

155

Estudio experimental del empuje sobre estructuras de contención en suelos reforzados con geomallas / Experimental study of the lateral earth pressure on retaining structures in soils reinforced with geogrids  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Este artículo presenta un estudio experimental de la variación de las tensiones de empuje sobre una pared que soporta un suelo reforzado con geomallas. Para ello se utilizó un equipo diseñado y construido especialmente para ejecutar ensayos de empuje bajo condiciones de deformación plana. Se describ [...] e el equipo de ensayo y los instrumentos de medición, así como el suelo y la preparación de las muestras de arena y la geomalla utilizada. En la primera etapa de la investigación se ensayan muestras sin reforzar y se comparan los resultados con aquellos provenientes de las teorías clásicas de empuje. Posteriormente se presentan los resultados de ensayos de empuje en suelo reforzado con una, dos, tres y cuatro geomallas. Se concluye que la incorporación de geomallas como refuerzo en el suelo disminuye el empuje ejercido por el suelo sobre la estructura de contención. Esta disminución del empuje es de aproximadamente un 25% cuando se usa una geomalla, un 50% con dos o tres geomallas y de un 75% con cuatro geomallas para los espaciamientos, sobrecargas e incremento de desplazamientos usados. Resultó posible identificar que la distribución de la tensión de empuje con la profundidad no sólo no sigue la variación triangular sino que se desarrollan arcos de tensiones en el suelo entre las geomallas. Abstract in english This article presents an experimental study on the variation with depth of the stresses due to lateral earth pressure on a wall retaining a soil reinforced with geogrids. To this end, an apparatus was designed and constructed especially tailored for performing lateral earth pressure tests under plai [...] n strain conditions. The experimental apparatus and the measurement instruments as well as the soil and the sample preparation and the geogrids used, are described. In a first stage of research, samples without reinforcing are tested and the results are compared with those from classic earth pressure theories. Subsequently, results from lateral earth pressure tests in soils reinforced with one, two, three and four geogrids are presented. It is concluded that the inclusion of geogrids as soil reinforcement reduces the earth pressure on the retaining structure. This lateral earth pressure reduction is approximately of 25% when one geogrid is used, 50% with two or three geogrids and 75% with four geogrids for the spacing, surcharges and displacement increments used. It was possible to identify that the lateral earth pressure distribution with depth not only does not follow a triangular variation, but it develops stress arching in the soil and between the geogrids.

Lissette, Ruiz-Tagle; Felipe, Villalobos.

2011-12-01

156

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

157

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

158

High-pressure rare earth silicates: Lanthanum silicate with barium phosphate structure, holmium silicate apatite, and lutetium disilicate type X  

International Nuclear Information System (INIS)

The phase relations of a wide selection of rare earth disilicates have been investigated up to 10 GPa and 1700 deg. C using piston cylinder and multi-anvil equipment. Single-crystal X-ray structures have been obtained for the following high-pressure phases: (1) La2.67(SiO4)2: monoclinic, space group C2/m, Z=2, a=9.419(2), b=5.445(1), c=7.214(1) A, ?=115.71(3)o, R=0.042; disordered Ba3(PO4)2 structure type, with 3xb and 7xb superstructures identified. (2) Ho8.67(SiO4)6(OH)2: hexagonal, P63/m, Z=1, a=9.3221(4), c=6.7347(2) A, R=0.026; silicate hydroxyapatite. (3) Lu2Si2O7: tetragonal, P41212, Z=4, a=6.5620(2), c=11.9535(4) A, R=0.023; type X diorthosilicate structure, and the silicate analogue of tetragonal Er2Ge2O7

159

Defect and intra-4f luminescence of rare earth doped group-III nitrides synthesized by high pressure high temperature method  

Energy Technology Data Exchange (ETDEWEB)

Cubic boron nitride (c-BN) and AlN exhibit the largest band gaps among all group-III nitrides with 6.2 and 6.0 eV, respectively. Both materials posses the ability for optoelectonic building blocks which can operate at high temperatures, high power, high frequencies and under extreme chemical conditions. The intensive and narrow intra-4f luminescence of rare earth doped c-BN and AlN crystals could be employed for laser diodes or in optical communication technology. Rare earth doped c-BN and AlN crystals were synthesized via the high temperature high pressure method, with temperatures and pressures between 1450-1620 C and 4.5-6.3 GPa, respectively. Ba{sub 3}B{sub 2}N{sub 4} and Li{sub 3}AlN{sub 2} were used as solvents with addition of rare earth fluorides as source material for the synthesis of c-BN and AlN, respectively. The luminescence of rare earth doped c-BN and AlN is a superposition of different defect transitions of the host material and intra-4f transitions of the rare earth dopant ion. Intrinsic defects as well as impurity defect complexes serve as origin for various defect bands in c-BN and AlN.

Mueller, Sven; Vetter, Ulrich; Hofsaess, Hans [Georg-August-Universitaet Goettingen (Germany). II. Physikalisches Institut; Taniguchi, Takashi [National Institute for Materials Science, Namiki, Tsukuba, Ibaraki (Japan)

2010-07-01

160

???????? ????????????? ?????????? ??? ??? ?????? ??? ??????? ?????????? ?? ????? ??? Google Earth  

Digital Repository Infrastructure Vision for European Research (DRIVER)

? ??????? ??????? ????? ?? ?????????? ?????????, ????????? ??? ??????????? ??? ????????????? ?????????? «????? ??????????: ? ?????????? ???». ? ???????? ??????????? ???? ??? «Google Earth» ??????????????? ?? ???????? ??? ??? ?????? ?? ?????? kmz. ??????????? ?? ?????????????...

???????, ?????

2010-01-01

 
 
 
 
161

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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,...

Farzin Salmasi; Behnam Mansuri

2013-01-01

162

The coefficient of earth pressure at rest and deformation and densification of granular soils subjected to static and dynamic loading  

Science.gov (United States)

The coefficient of earth pressure at rest, Ko, of granular soil deposits and backfills is a significant parameter in geotechnical engineering profession. A knowledge of Ko value in granular deposits and backfills not only is necessary for many geotechnical construction, but could also assist engineers and researchers in interpretations of laboratory and in situ tests. The primary purpose of the study is to gain a better understanding of K o behavior of granular soils during loading, unloading, and vibration, especially produced by vibratory surface compaction equipments. Compressibility and rebound behaviors of granular soils were studied, and effect of particle damage on Ko and one-dimensional compression behavior were also reviewed. Influence of dynamic stress characteristics, including maximum dynamic vertical stress increase and frequency, on the change in Ko and minimum achievable void ratio of granular soils during vibration were determined. A comprehensive laboratory testing program, mainly the series of oedometer test with lateral stress measurement, were conducted on Ottawa, Lake Michigan Beach, Niigata, and Toyoura sand. Reconstituted dry sand specimens were subjected to 7 different loading histories, and the maximum effective vertical stress was 341 kPa. Different characteristics of dynamic vertical stresses, including periodic impulse stresses (f = 61 Hz, fp = 1,170 Hz), approximately sinusoidal dynamic stresses (f = 60 to 120 Hz, fp = 120 to 180 Hz), as well as 'cyclic loading' (loading-unloading-reloading, f ? 0 Hz), with various maximum dynamic stress amplitudes and durations of vibration, were applied to the sand specimens. A total of 155 oedometer tests with lateral stress measurement were completed. Particle modification, if any occurred during the oedometer test, was investigated through results of grain size and SEM analyses of sand particles before and after the oedometer test, and compression behavior of sand specimens observed during the oedometer test.

Vardhanabhuti, Barames

163

In-situ sound velocity measurements at high pressure and high temperature using Brillouin spectroscopy with synchrotron radiation and infrared laser heating system. Application to the deep earth science  

International Nuclear Information System (INIS)

Average composition and structure of the Earth's deep interior can be approached by comparing observed seismic velocities to appropriate laboratory sound velocity data collected for candidate minerals under relevant pressure and temperature conditions. Simultaneous measurement of sound velocities and densities also enable us to construct a primary pressure scale, which can independently determine the pressure. Our newly developed high-pressure and high-temperature sound velocity measurement system using Brillouin spectroscopy with synchrotron radiation and infrared laser heating techniques has proven to be highly suitable for establishments of Earth's mineralogical model and the primary pressure scale. (author)

164

Quiet time plasma pressure distribution in the Earth's magnetospheric trap calculated on the basis of the existing models of trapped radiation  

International Nuclear Information System (INIS)

One of the main parameters, which control the generation of currents and electric fields in the magnetospheric trap, is the plasma pressure. At present the complete picture of the plasma pressure distribution in the magnetospheric trap has not been obtained yet. Trapped particles of the radiation belts provide a considerable part of plasma pressure at low L-shells. The evaluations of this part during quiet times can be made on the basis of existing trapped radiation models. The radial profiles of plasma pressure at 1.2< L<7 were obtained using the trapped radiation model AP8 MAX (L<6.6) and the theoretical model of the distribution of the proton fluxes in the Earth's radiation belts (L<7) developed on the basis of the numerical solution of the radial diffusion equation with dissipation processes. The calculations were compared with AMPTE/CCE data. It was shown that they are in good agreement at low L-shells. The magnetic field produced by such pressure profiles is analyzed. During the magnetospheric disturbances only the outer part of this pressure distribution is changed. The observed magnetic field disturbance is a result of the difference between the disturbed and quiet-time plasma pressure profiles. The role of geomagnetically effective eastward ring current existing near the inner edge of the plasma sheet is analyzed

165

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

166

Balance Checklist  

Science.gov (United States)

... America Exercise Director, Parkinson Association of SW Florida Balance Checklist Balance can be defined as the ability to the ... or moving. Good Posture is critical to good balance. When the body is correctly aligned, movement is ...

167

Russia - Nato. The military balance  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This project aims to explain how the military balancing of Russia against NATO can be explained from a neoclassical realist framework. The project consists in three analytical parts of respectively, 1: The military capabilities balance between NATO and Russia; 2: How the international system puts pressure on Russia; and 3: How the strategic culture of Russia can explain its balancing.

Daugaard, Søren Bech; Jacobsen, Karen Vesterga?rd; Aigro, Signe; Skarequist, Anne

2010-01-01

168

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

169

Striking a Solar Balance  

Science.gov (United States)

This NASA video reviews the role of the sun in driving the climate system. It uses colorful animations to illustrate Earth's energy balance and how increased greenhouse gases are creating an imbalance in the energy budget, leading to warming. The video also reviews how the NASA satellite program collects data on the sun.

Nasa; Nasa.gov/multimedia

170

Experimental Study on the Performance of the Passive Safety Injection for Pressure Balance Line Break and Direct Vessel Injection Line Break  

International Nuclear Information System (INIS)

A passive core cooling system (PCCS) has been installed at the Institute of Nuclear Energy Research (INER) Integral System Test (IIST) facility. It includes three core makeup tanks (CMTs), three accumulators (ACCs), a-four stage automatic depressurization system (ADS), a passive residual heat removal (PRHR) heat exchanger submerged into an in-containment refueling water storage tank (IRWST). The purpose of this research is to study the performance of the PCCS with passive injection during either a pressure balance line (PBL) break or a direct vessel injection (DVI) line break. Five experiments were performed simulating break area ratios of 0.5% to 2.0% (1.88 mm to 3.77 mm) at either a PBL or at a DVI-line. The general system response and the interactions of CMT, ACC, PRHR, and IRWST to the effect of core heat removal are observed and discussed. The experimental results show long term core cooling can be reached for the cases of the PBL break and the DVI-line break following the PCCS actuation procedures. (authors)

171

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.

SchiØttz-Christensen, Berit

2012-01-01

172

Experimental investigation of anaerobic nitrogen fixation rates with varying pressure, temperature and metal concentration with application to the atmospheric evolution of early Earth and Mars.  

Science.gov (United States)

The atmosphere of the early Earth is thought to have been significantly different than the modern composition of 21% O2 and 78% N2, yet the planet has been clearly established as hosting microbial life as far back as 3.8 billion years ago. As such, constraining the atmospheric composition of the early Earth is fundamental to establishing a database of habitable atmospheric compositions. A similar argument can be made for the planet Mars, where nitrates have been hypothesized to exist in the subsurface. During the early period on Mars when liquid water was likely more abundant, life may have developed to take advantage of available nitrates and a biologically-driven Martian nitrogen cycle could have evolved. Early Earth atmospheric composition has been investigated numerically, but only recently has the common assumption of a pN2 different than modern been investigated. Nonetheless, these latest attempts fail to take into account a key atmospheric parameter: life. On modern Earth, nitrogen is cycled vigorously by biology. The nitrogen cycle likely operated on the early Earth, but probably differed in the metabolic processes responsible, dominantly due to the lack of abundant oxygen which stabilizes oxidized forms of N that drive de-nitrification today. Recent advances in evolutionary genomics suggest that microbial pathways that are relatively uncommon today (i.e. vanadium and iron-based nitrogen fixation) probably played important roles in the early N cycle. We quantitatively investigate in the laboratory the effects of variable pressure, temperature and metal concentration on the rates of anoxic nitrogen fixation, as possible inputs for future models investigating atmospheric evolution, and better understand the evolution of the nitrogen cycle on Earth. A common anaerobic methanogenic archaeal species with i) a fully sequenced genome, ii) all three nitrogenases (molybdenum, vanadium and iron-based) and iii) the ability to be genetically manipulated will be used as a model species. This species will be genetically modified to create knock-out mutants lacking one or more nitrogenase genes. These mutants will be used in variable pressure, temperature and metal-concentration experiments. Nitrogen fixation rate and nitrogenase gene expression will be measured using isotope dilution and quantitative polymerase chain reaction, respectively.

Gupta, Prateek

2012-07-01

173

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

174

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.

175

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

176

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

177

Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride charge density wave compounds  

CERN Document Server

We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing lattice constant across the rare-earth series. We propose a possible mechanism describing this behavior and we suggest the presence of a one-dimensional character in these two-dimensional compounds. We also envisage that interactions and umklapp processes might play a relevant role in the formation of the charge-density-wave state in these compounds.

Sacchetti, A; Giamarchi, T; Ru, N; Fisher, I R

2006-01-01

178

Balance failure in single limb stance due to ankle sprain injury: an analysis of center of pressure using the fractal dimension method.  

Science.gov (United States)

Instrumented postural control analysis plays an important role in evaluating the effects of injury on dynamic stability during balance tasks, and is often conveyed with measures based on the displacement of the center-of-pressure (COP) assessed with a force platform. However, the desired outcome of the task is frequently characterized by a loss of dynamic stability, secondary to injury. Typically, these failed trials are discarded during research investigations, with the potential loss of informative data pertaining to task success. The novelty of the present study is that COP characteristics of failed trials in injured participants are compared to successful trial data in another injured group, and a control group of participants, using the fractal dimension (FD) method. Three groups of participants attempted a task of eyes closed single limb stance (SLS): twenty-nine participants with acute ankle sprain successfully completed the task on their non-injured limb (successful injury group); twenty eight participants with acute ankle sprain failed their attempt on their injured limb (failed injury group); sixteen participants with no current injury successfully completed the task on their non-dominant limb (successful non-injured group). Between trial analyses of these groups revealed significant differences in COP trajectory FD (successful injury group: 1.58±0.06; failed injury group: 1.54±0.07; successful non-injured group: 1.64±0.06) with a large effect size (0.27). These findings demonstrate that successful eyes-closed SLS is characterized by a larger FD of the COP path when compared to failed trials, and that injury causes a decrease in COP path FD. PMID:24746034

Doherty, Cailbhe; Bleakley, Chris; Hertel, Jay; Caulfield, Brian; Ryan, John; Delahunt, Eamonn

2014-05-01

179

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  

Energy Technology Data Exchange (ETDEWEB)

Fire is the primary terrestrial ecosystem disturbance agent on a global scale. It affects carbon balance of global terrestrial ecosystems by emitting carbon to atmosphere directly and immediately from biomass burning (i.e., 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 (i.e., fire indirect effect). Here, we provide the first quantitative assessment about the impact of fire on the net carbon balance of global terrestrial ecosystems for the 20th century, and investigate the roles of fire direct and indirect effects. This study is done by quantifying the difference between the 20th century fire-on and fire-off simulations with NCAR community land model CLM4.5 as the model platform. Results show that fire decreases net carbon gain of the global terrestrial ecosystems by 1.0 Pg C yr-1 average across the 20th century, as a results of fire direct effect (1.9 Pg C yr-1) partly offset by indirect effect (-0.9 Pg C yr-1). Fire generally decreases the average carbon gains of terrestrial ecosystems in post-fire regions, which are significant over tropical savannas and part of forests in North America and the east of Asia. The general decrease of carbon gains in post-fire regions is because fire direct and indirect effects have similar spatial patterns and the former (to decrease carbon gain) is generally stronger. Moreover, the effect of fire on net carbon balance significantly declines prior to ~1970 with trend of 8 Tg C yr-1 due to increasing fire indirect effect and increases afterward with trend of 18 Tg C yr-1 due to increasing fire direct effect.

Li, Fang; Bond-Lamberty, Benjamin; Levis, Samuel

2014-03-07

180

New high-pressure and high-temperature metal/silicate partitioning of U and Pb: Implications for the cores of the Earth and Mars  

International Nuclear Information System (INIS)

In order to quantify possible fractionation of U and Pb into a metallic core, we have performed piston cylinder and multi-anvil press experiments at high pressure (up to 20 GPa) and high temperature (up to 2400 degrees C) and obtained the distribution coefficient D(metal-silicate) and the exchange partition coefficient K(metal-silicate) for these elements between metal and silicates (mineral or liquid). DPb(metal-silicate) and DU(metal-silicate) depend strongly on the S content of the metallic phase, and also on the oxygen fugacity, in agreement with an effective valence state of 4 for U in silicates and 2 for Pb in silicates. KdPb( metal-silicate) and KdU(metal-silicate) show no discernable pressure and temperature trend. U remains lithophile even at high pressure and high temperature but its lithophile nature decreases at very low oxygen fugacity. From our experimental data, it was possible to calculate the U and Pb contents of the cores of Mars and Earth under core-mantle equilibrium conditions at high pressure and high temperature. From the D(metal-silicate) of the present study, we obtained that: 0.008 ppm ? Pb (in the core) ? 4.4 ppm, and 0.0003 ppb ? U (in the core) ? 0.63 ppb, depending on whether the metal is S-free or S-saturated respectively, and if the mantle was molten or solid during the segregation process of the Earth's core around ?IW-2. For Mars, based on a core segregation process around ?IW-1, wregation process around ?IW-1, we obtained that: 0.005 ppm ? Pb (in the core) ? 3 ppm, and 0.00002 ppb ? U (in the core) < 0.05 ppb, depending on the metallic composition: S-free or S-saturated respectively. Our results suggest that the low concentration of Pb in the terrestrial mantle could not be explained by an early Pb sequestration in the Earth's core even if S is the dominant light element of the core. If we assume a magma ocean scenario, U might produced a maximum value of 1.5% of the total heat budget of the core with a segregation occurring below ?IW-3. The values found in the present study for U in the Martian core suggest that the magnetic field activity of Mars before ? 0.5 b.y. after its formation would be difficult to ascribe to the decay of U alone. (authors)

 
 
 
 
181

Balance Disorders  

Science.gov (United States)

... stand up too quickly. Problems that affect the skeletal or visual systems, such as arthritis or eye ... your body, such as your vision and your musculoskeletal sensory system, to ... of balance disorders? There are more than a dozen different balance ...

182

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

183

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

184

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

185

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

Science.gov (United States)

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.

Khenata, R.; Sahnoun, M.; Baltache, H.; Rérat, M.; Rached, D.; Driz, M.; Bouhafs, B.

2006-01-01

186

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

187

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

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

Cloud and surface control on the Earth's net radiation balance and the role of atmospheric/oceanic energy transports: A satellite perspective  

Science.gov (United States)

The two dimensional 5 year mean energy transport potential function, based on the Nimbus-7 ERB (Earth Radiation Budget) measurements, shows an east-west coupled dipole structure in which North Africa is the major energy sink and the western Pacific is the major energy source. In conjunction with the dipole, the cross-meridional transports are up to 30 percent of the tropical north-south transports. This is the main justification for the importance of the east-west energy transport. The separation of the required energy transport into oceanic and atmospheric components based on the maximum entropy production reveals that cross-meridional energy transports in the oceanic areas are mainly achieved by the ocean fluid. Cloud-radiation feedback shows that cloud-induced long wave warming (cloud greenhouse influence) is dominant over the tropics whereas cloud-induced short wave cooling (cloud albedo influence) is dominant in the mid- and high-latitudes. These differential distributions result in a global net cloud cooling effect of -2.1 W m(exp -2).

Sohn, Byung-Ju

1990-08-01

191

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

192

High-pressure polymorphism of Fe[subscript 2]P and its implications for meteorites and Earth's core  

Energy Technology Data Exchange (ETDEWEB)

Minerals with composition (Fe,Ni){sub 2}P, are rare, though important accessory phases in iron and chondritic meteorites. The occurrence of these minerals in meteorites is believed to originate either from the equilibrium condensation of protoplanetary materials in solar nebulae or from the later accretion and condensation processes in the cores of parent bodies. Fe-Ni phosphides are considered a possible candidate for a minor phase present in the Earth's core, and at least partially responsible for the observed density deficit with respect to pure iron. We report results of high-pressure high-temperature X-ray diffraction experiments with synthetic barringerite (Fe{sub 2}P) up to 40 GPa and 1400 K. A new phase transition to the Co{sub 2}Si-type structure has been found at 8.0 GPa, upon heating. The high-pressure phase can be metastably quenched to ambient conditions at room temperature, and then, if heated again, transforms back to barringerite, providing an important constraint on the thermodynamic history of meteorite.

Dera, P.; Lavina, B.; Borkowski, L.A.; Prakapenka, V.B.; Sutton, S.R.; Rivers, M.L.; Downs, R.T.; Boctor, N.Z.; Prewitt, C.T. (UNLV); (UofC); (Univ of AZ); (CIW)

2008-05-19

193

Balancing Work and Family: A Panel Analysis of the Impact of Part-Time Work on the Experience of Time Pressure  

Science.gov (United States)

In this article we consider the consequences of work-family reconciliation, in terms of the extent to which the adjustment of the labour market career to family demands (by women) contributes to a better work-life balance. Using the Flemish SONAR-data, we analyse how changes in work and family conditions between the age of 26 and 29 are related to…

Laurijssen, Ilse; Glorieux, Ignace

2013-01-01

194

Solubility of Uranium in Fe-S-Si Melts at High Pressure and Temperature and at Highly Reducing Conditions: Uranium as a heat source in the Earth's Core?  

Science.gov (United States)

The presence of Uranium and its role as a radioactive heat source in the Earth's Fe-metallic core has been controversial (e.g., Wheeler et al., 2006; Bao et al., 2005). We report here on partitioning of U between molten enstatite chondrite and Fe-S-Si melts at about 4 log units below the Iron-Wustite oxygen buffer and pressures between 3 and 8 GPa. All experiments were performed at super-liquidus temperatures in the range of 2000- 2400 C. Both the metal and silicates were completely molten, in keeping with the concept of an early global magma ocean. At these pressures and temperatures, the partition coefficient, DU (U concentration in metallic sulfide liquid/U concentration in molten silicate) is in the range of 0.03-0.08. DU is positively correlated with S as observed in prior studies (Bao et al., 2005; Wheeler et al., 2006), but is inversely correlated with Si in metallic liquid. In metal with little or no sulfur, DU is lower by an order of magnitude or more. In the range of our measurements, no strong effect of either T or P on the partition coefficient is observed. U shows no correlation with Ca suggesting that U is not carried via CaS at these highly reducing conditions, as has been suggested (Murrell and Burnett, 1982; Furst et al., 1982). Nor does the U content of metal-sulfide have any discernible dependency on the O content of the metallic liquid. Thus it appears that neither Ca nor O act as carriers or catalytic agents for the entry of U into Fe-S melts. Rather, we suggest that the reaction UO2 +2 FeS = US2 +2FeO proceeds to the right at elevated P and T and highly reducing conditions, facilitating the incorporation of U in Fe-S liquids. Assuming that the behavior of DU is not significantly changed at the much higher P and T relevant to the magma ocean, our data permit 0.6-1.8 ppb of U in the core with heat production capacity of 0.1-0.3 TW at present, a small fraction of the 6-12 TW total heat flux from the core (Buffet, 2003). We conclude that under highly reducing conditions uranium might be incorporated into the Earth's metallic core.

Murthy, V.; Draper, D. S.; Agee, C. B.

2006-12-01

195

Balancing Stick  

Science.gov (United States)

In this quick and simple activity, learners explore how the distribution of the mass of an object determines the position of its center of gravity, its angular momentum, and your ability to balance it. Learners discover it is easier to balance a wooden dowel on the tip of their fingers when a lump of clay is near the top of the stick. Use this activity to introduce learners to rotational inertia.

Exploratorium, The

2014-02-03

196

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

197

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

198

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.

199

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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.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

2005-06-01

200

Production balance  

International Nuclear Information System (INIS)

In terms of the environment, the year 2011 was balanced in the company Slovenske elektrarne. The trend of a high share of electricity production from nuclear and hydro power plants persisted; therefore, a greater part of electricity supplies (88.5%) was not loaded by emissions of harmful substances into the atmosphere. (author)

 
 
 
 
201

Balance Problems  

Science.gov (United States)

... of falls and fall-related injuries, such as hip fracture. Some balance problems are due to problems in the inner ear. Others may involve another part of the body, such as the brain or the heart. Aging, infections, head injury, certain medicines, or problems with blood ...

202

Balancing Act.  

Science.gov (United States)

Reviews family-friendly policies such as flextime, child care referral, job sharing and parental leave; examines how such policies work in postsecondary institutions, corporations, and small businesses; describes curricular approaches to balancing work and family; and lists work and family resource organizations. (SK)

Lozada, Marlene

1997-01-01

203

X-ray Raman scattering study of MgSiO3 glass at high pressure: Implication for triclustered MgSiO3 melt in Earth's mantle  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Silicate melts at the top of the transition zone and the core-mantle boundary have significant influences on the dynamics and properties of Earth's interior. MgSiO3-rich silicate melts were among the primary components of the magma ocean and thus played essential roles in the chemical differentiation of the early Earth. Diverse macroscopic properties of silicate melts in Earth's interior, such as density, viscosity, and crystal-melt partitioning, depend on their electronic and short-range loc...

Lee, Sung Keun; Lin, Jung-fu; Cai, Yong Q.; Hiraoka, Nozomu; Eng, Peter J.; Okuchi, Takuo; Mao, Ho-kwang; Meng, Yue; Hu, Michael Y.; Chow, Paul; Shu, Jinfu; Li, Baosheng; Fukui, Hiroshi; Lee, Bum Han; Kim, Hyun Na

2008-01-01

204

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

205

Separation of the rare earths by high pressure liquid chromatography and the fission yield on sup(148m)Pm and sup(148g)Pm using thermal neutron induced fission of 233U and 239Pu  

International Nuclear Information System (INIS)

This report is in two parts: in the first part, the method of high pressure liquid chromatography is described with particular reference to rare earth nuclei produced in nuclear reactions; in the second part, the results of a study of the fission yield of sup(148m)Pm and sup(148g)Pm from the thermal fission of 233U and 239Pu are presented. (G.T.H.)

206

Lunar Balance and Locomotion  

Science.gov (United States)

Balance control and locomotor patterns were altered in Apollo crewmembers on the lunar surface, owing, presumably, to a combination of sensory-motor adaptation during transit and lunar surface operations, decreased environmental affordances associated with the reduced gravity, and restricted joint mobility as well as altered center-of-gravity caused by the EVA pressure suits. Dr. Paloski will discuss these factors, as well as the potential human and mission impacts of falls and malcoordination during planned lunar sortie and outpost missions. Learning objectives: What are the potential impacts of postural instabilities on the lunar surface? CME question: What factors affect balance control and gait stability on the moon? Answer: Sensory-motor adaptation to the lunar environment, reduced mechanical and visual affordances, and altered biomechanics caused by the EVA suit.

Paloski, William H.

2008-01-01

207

Uniqueness of Herndon's Georeactor: Energy Source and Production Mechanism for Earth's Magnetic Field  

CERN Document Server

Herndon's georeactor at the center of Earth is immune to meltdown, which is not the case for recently published copy-cat georeactors, which would necessarily be subject to hot nuclear fuel, prevailing high temperature environments, and high confining pressures. Herndon's georeactor uniquely is expected to be self-regulating through establishing a balance between heat production and actinide settling out. The seven decade old idea of convection in the Earth's fluid core is refuted because thermal expansion cannot overcome the 23 percent higher density at the core's bottom than at its top. Some implications of geomagnetic field production within Herndon's georeactor are briefly described.

Herndon, J Marvin

2009-01-01

208

THE COSMIC-RAY INTENSITY NEAR THE ARCHEAN EARTH  

International Nuclear Information System (INIS)

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.

209

The Cosmic-Ray Intensity near the Archean Earth  

Science.gov (United States)

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.; Kóta, J.

2012-11-01

210

Development of high temperature reference electrodes for in-pile application: Part I. Feasibility study of the external pressure balanced Ag/AgCl reference electrode (EPBRE) and the cathodically charged Palladium hydrogen electrode  

International Nuclear Information System (INIS)

The main problems connected with corrosion potential measurements at elevated temperatures and pressures are related to the stability and lifetime of the reference electrode and the correct estimation of the potential related to the Standard Hydrogen Scale (SHE). Under Pressurised Water Reactor (PWR) conditions of 300 degrees Celsius and 150 bar, the choice of materials is also a limiting factor due to the influence of radiation. Investigations on two reference electrodes that can be used under PWR conditions are reported: the cathodically charged palladium hydrogen electrode, and the external pressure balanced silver/silver chloride electrode. Preliminary investigations with the Pd-electrode were focused on the calculation of the required charging time and the influence of dissolved oxygen. High temperature applications are discussed on the basis of results reported in the literature. Investigations with the silver/silver chloride reference electrode mainly dealt with the salt bridge which is necessary to connect the reference electrode with the testing solution. It is shown that the thermal junction potential is independent of the length of the salt bridge. In addition, the high temperature contributes to an increase of the conductivity of the solution, which is beneficial for the salt bridge connection

211

Ballet Balance Strategies  

DEFF Research Database (Denmark)

Animating physically realistic human characters is challenging, since human observers are highly tuned to recognize human cues such as emotion and gender from motion patterns. The main contribution of this paper is a new model firmly based on biomechanics, which is used to animate balance and basic movements of a ballet dancers. It is supported by computer simulated experiments and it is in good agreement with biomechanical measurements of real-life dancers. Our results questions the previous approaches in dynamic animation, which only uses the center of gravity strategy, and instead demonstrate the viability of the center of pressure strategy.

Pedersen, Camilla; Erleben, Kenny

2006-01-01

212

Improve Your Balance  

Science.gov (United States)

... My Go4Life Get Free Stuff Be A Partner Balance Improve Your Balance Each year, more than 2 million older Americans ... types of exercise — endurance , strength , balance, and flexibility . Balance Stand on One Foot Heel-to-Toe Walk ...

213

Striking a Balance: Less Sodium (Salt), More Potassium  

Science.gov (United States)

Striking a Balance: Less Sodium (Salt), More Potassium Updated:Oct 7,2014 In your battle against high blood pressure, sodium (salt) ... and calcium and magnesium. Potassium also affects the balance of fluids in your body. So talk to ...

214

Observation of vapor pressure enhancement of rare-earth metal-halide salts in the temperature range relevant to metal-halide lamps  

Energy Technology Data Exchange (ETDEWEB)

Total vapor-phase densities of Dy in equilibrium with a DyI{sub 3}/InI condensate and Tm in equilibrium with a TmI{sub 3}/TlI condensate have been measured for temperatures between 900 K and 1400 K. The measurements show strong enhancements in rare-earth vapor densities compared to vapors in equilibrium with the pure rare-earth metal-halides. The measurements were made with x-ray induced fluorescence on the sector 1-ID beam line at the Advanced Photon Source. The temperature range and salt mixtures are relevant to the operation of metal-halide high-intensity discharge lamps.

Curry, J. J.; Henins, A.; Hardis, J. E. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Estupinan, E. G. [Osram Sylvania Inc., Beverly, Massachusetts 01915 (United States); Lapatovich, W. P. [Independent Consultant, 51 Pye Brook Lane, Boxford, Massachusetts 01921 (United States); Shastri, S. D. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2012-02-20

215

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

216

Balance in Assessment  

Science.gov (United States)

The review by Black and Wiliam of national systems makes clear the complexity of assessment, and identifies important issues. One of these is "balance": balance between local and central responsibilities, balance between the weights given to various purposes of schooling, balance between weights for various functions of assessment, and balance

White, Richard

2007-01-01

217

30 CFR 816.57 - Hydrologic balance: Activities in or adjacent to perennial or intermittent streams.  

Science.gov (United States)

... 2010-07-01 false Hydrologic balance: Activities in or adjacent to perennial...ACTIVITIES § 816.57 Hydrologic balance: Activities in or adjacent to perennial...h) of this chapter and that earth materials, ground-water discharges, and...

2010-07-01

218

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  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Frueh, Carolin; Jah, Moriba; Kelecy, Thomas

2013-01-01

219

Estudio experimental y numérico del desplazamiento y rotación de suelo reforzado con geomallas bajo empuje activo Experimental and numerical study of the displacement and rotation of geogrid reinforced soil under active lateral earth pressure  

Directory of Open Access Journals (Sweden)

Full Text Available Se presenta un estudio experimentaly numérico de desplazamiento y rotación de suelo sin y con refuerzo de geomallas bajo la acción del empuje activo. Para ello se ha usado la técnica de medición PIV con la cual se procesan imágenes digitales para la obtención de campos de desplazamiento y rotación. El equipo de ensayo de empuje posee una ventana transparente que permite registrar el movimiento del suelo. Los resultados medidos de movimiento del suelo permiten determinar áreas de suelo que fluyen y no fluyen debido a la acción del empuje activo. De esta manera se puede determinar la posición y geometría de la superficie de falla, la cual se puede comparar con la definida por la teoría de la plasticidad de empuje activo de Rankine. Esta comparación resulta solo posible para el caso sin geomallas, dado que con geomallas la zona de suelo en fluencia cambia significativamente. La presencia de geomallas puede reducir hasta dos veces el volumen de suelo que entra en fluencia debido al empuje activo. Esta conclusión relacionada con la deformación del suelo está en directa relación con la disminución de la tensión de empuje activo al utilizar geomallas como elementos de refuerzo. También se presenta un análisis numérico usando el programa computacional Plaxis para estimar los desplazamientos horizontales. Los resultados numéricos entregan estimaciones que se aproximan a los resultados medidos de desplazamientos horizontales en términos de la forma de la zona de suelo en fluencia. Sin embargo, no son capaces de reproducir en detalle la geometría de la superficie de falla.An experimental and numerical study is presented related to displacement and rotation of soil with and without geogrid reinforcement under the application of active lateral earth pressure. To this end, the measurement technique PIV has been used, with which digital images are processed to obtain displacement and rotation fields. The experimental earth pressure equipment has a transparent window which allows the recording of soil movements. Through the process and analysis of the measured soil movement, soil areas which yielded and did not yield due to the active earth pressure, were defined. In this form, the position and geometry of the failure surface can be determined and compared with the defined by the plasticity theory of active Rankine states. This comparison is only possible for the case without geogrids since the presence of geogrids change significantly the zone of soil yielding. Geogrids can reduce up to twice the volume of soil yielding due to the active lateral earth pressure. This conclusion related with the soil deformation is in direct relation with the active lateral earth pressure reduction when geogrids are used as reinforced elements. In addition, a numerical analysis using the computational program Plaxis is presented to estimate horizontal displacements. The numerical results estimate reasonably well the horizontal displacements measured in terms of the shape of the soil yielding area. However, they do not reproduce in detail the geometry of the failure surface.

Lissette Ruiz-Tagle

2011-01-01

220

Estudio experimental y numérico del desplazamiento y rotación de suelo reforzado con geomallas bajo empuje activo / Experimental and numerical study of the displacement and rotation of geogrid reinforced soil under active lateral earth pressure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Se presenta un estudio experimentaly numérico de desplazamiento y rotación de suelo sin y con refuerzo de geomallas bajo la acción del empuje activo. Para ello se ha usado la técnica de medición PIV con la cual se procesan imágenes digitales para la obtención de campos de desplazamiento y rotación. [...] El equipo de ensayo de empuje posee una ventana transparente que permite registrar el movimiento del suelo. Los resultados medidos de movimiento del suelo permiten determinar áreas de suelo que fluyen y no fluyen debido a la acción del empuje activo. De esta manera se puede determinar la posición y geometría de la superficie de falla, la cual se puede comparar con la definida por la teoría de la plasticidad de empuje activo de Rankine. Esta comparación resulta solo posible para el caso sin geomallas, dado que con geomallas la zona de suelo en fluencia cambia significativamente. La presencia de geomallas puede reducir hasta dos veces el volumen de suelo que entra en fluencia debido al empuje activo. Esta conclusión relacionada con la deformación del suelo está en directa relación con la disminución de la tensión de empuje activo al utilizar geomallas como elementos de refuerzo. También se presenta un análisis numérico usando el programa computacional Plaxis para estimar los desplazamientos horizontales. Los resultados numéricos entregan estimaciones que se aproximan a los resultados medidos de desplazamientos horizontales en términos de la forma de la zona de suelo en fluencia. Sin embargo, no son capaces de reproducir en detalle la geometría de la superficie de falla. Abstract in english An experimental and numerical study is presented related to displacement and rotation of soil with and without geogrid reinforcement under the application of active lateral earth pressure. To this end, the measurement technique PIV has been used, with which digital images are processed to obtain dis [...] placement and rotation fields. The experimental earth pressure equipment has a transparent window which allows the recording of soil movements. Through the process and analysis of the measured soil movement, soil areas which yielded and did not yield due to the active earth pressure, were defined. In this form, the position and geometry of the failure surface can be determined and compared with the defined by the plasticity theory of active Rankine states. This comparison is only possible for the case without geogrids since the presence of geogrids change significantly the zone of soil yielding. Geogrids can reduce up to twice the volume of soil yielding due to the active lateral earth pressure. This conclusion related with the soil deformation is in direct relation with the active lateral earth pressure reduction when geogrids are used as reinforced elements. In addition, a numerical analysis using the computational program Plaxis is presented to estimate horizontal displacements. The numerical results estimate reasonably well the horizontal displacements measured in terms of the shape of the soil yielding area. However, they do not reproduce in detail the geometry of the failure surface.

Lissette, Ruiz-Tagle; Felipe, Villalobos.

 
 
 
 
221

Interstellar Turbulence, Cloud Formation and Pressure Balance  

CERN Document Server

We discuss HD and MHD compressible turbulence as a cloud-forming and cloud-structuring mechanism in the ISM. Results from a numerical model of the turbulent ISM at large scales suggest that the phase-like appearance of the medium, the typical values of the densities and magnetic field strengths in the intercloud medium, as well as Larson's velocity dispersion-size scaling relation in clouds may be understood as consequences of the interstellar turbulence. However, the density-size relation appears to only hold for the densest simulated clouds, there existing a large population of small, low-density clouds, which, on the other hand, are hardest to observe. We then discuss several tests and implications of a fully dynamical picture of interstellar clouds. The results imply that clouds are transient, constantly being formed, distorted and disrupted by the turbulent velocity field, with a fraction of these fluctuations undergoing gravitational collapse. Simulated line profiles and estimated cloud lifetimes are co...

Vázquez-Semadeni, E

1998-01-01

222

Earth's Background Free Oscillations  

Science.gov (United States)

Earth's background free oscillations, known as Earth's hum, were discovered in 1998. Excited modes of the oscillations are almost exclusively fundamental spheroidal and toroidal modes from 2 to 20 mHz. Seasonal variations in the source distribution suggest that the dominant sources are ocean infragravity waves in the shallow and deep oceans. A probable excitation mechanism is random shear traction acting on the sea bottom owing to linear topographic coupling of the infragravity waves. Excitation by pressure sources on Earth's surface is also significant for a frequency below 5 mHz. A possible pressure source is atmospheric turbulence, which can cause observed resonant oscillations between the solid modes and atmospheric acoustic modes.

Nishida, Kiwamu

2013-05-01

223

An Analog Earth Climate Model  

Science.gov (United States)

The earth climate is broadly governed by the radiative power of the sun as well as the heat retention and convective cooling of the atmosphere. I have constructed an analog earth model for an undergraduate climate class that simulates mean climate using these three parameters. The ‘earth’ is a hollow, black, bronze sphere (4 cm diameter) mounted on a thin insulated rod, and illuminated by two opposite optic fibers, with light focused on the sphere by a set of lenses. The sphere is encased in a large double-walled aluminum cylinder (34 cm diameter by 26 cm high) with separate water cooling jackets at the top, bottom, and sides. The cylinder can be filled with a gas of choice at a variety of pressures or can be run in vacuum. The exterior is cladded with insulation, and the temperature of the sphere, atmosphere and walls is monitored with thermocouples. The temperature and waterflow of the three cooling jackets can be monitored to establish the energy output of the whole system; the energy input is the energy yield of the two optic fibers. A small IR transmissive lens at the top provides the opportunity to hook up the fiber of a hyper spectrometer to monitor the emission spectrum of the black ‘earth’ sphere. A pressure gauge and gas inlet-outlet system for flushing of the cell completes it. The heat yield of the cooling water at the top is the sum of the radiative and convective components, whereas the bottom jacket only carries off the radiative heat of the sphere. Undergraduate E&ES students at Wesleyan University have run experiments with dry air, pure CO2, N2 and Ar at 1 atmosphere, and a low vacuum run was accomplished to calibrate the energy input. For each experiment, the lights are flipped on, the temperature acquisition routine is activated, and the sphere starts to warm up until an equilibrium temperature has been reached. The lights are then flipped off and the cooling sequence towards ambient is registered. The energy input is constant for a given experiment. For each time increment the radiative heat loss of the sphere is calculated from the Stefan Boltzman expression using the observed temperature at that time. The heating of the ‘earth sphere’ is accounted for in the energy balance equation by applying the temperature increase per time increment with the specific heat of bronze. The remaining energy term is the sum of the convective cooling and greenhouse effect. The heat budgets of the cooling trajectories were calculated analogous, with radiative and convective cooling causing the temperature drop per time increment. The greenhouse component again is lumped with the convective term. Equilibrium temperatures of 50-70 C were reached, with ambient temperature at 22 C. Somewhat surprising, experiments with radiatively neutral pure Argon gas yielded the highest equilibrium temperatures. Argon had the lowest specific heat of the gases used, and the observed equilibrium temperatures for different cell gases broadly scaled inversely with the heat capacity of those gases. Apparently, the efficiency of the free convective cooling strongly impacts the equilibrium temperatures. The greenhouse effects possibly have only a minor impact on final temperature as a result of the short cell pathlength. Experiments at higher cell filling pressures may provide more insight in this.

Varekamp, J. C.

2010-12-01

224

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

225

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 ...

226

Dizziness and Balance  

Science.gov (United States)

... Information Series © ASHA 2011 7976-3 Dizziness and Balance AUDIOLOGY Information Series Our balance system helps us ... I do if I have a problem with balance or dizziness? It is important to see your ...

227

Snowball Earth  

Science.gov (United States)

Audio program from the University of Wisconsin's Earthwatch Radio discusses the notion of the entire planet covered with ice. Doug Macdougall is an earth scientist at the University of California-San Diego and author of a new book called "Frozen Earth." He says the planet-wide freeze is known as "Snowball Earth."

228

Mars, earth, and ice  

International Nuclear Information System (INIS)

Possible mechanisms to explain the global ice covering of Mars, and previous ice ages on the earth, are considered. Evidence for the Milankovitch effect is found in the close correspondence of earth's past climate with its orbital variations, as recorded principally in ocean sediments, and the role of CO2 is discussed. Mars' range of obliquity, 10 times that of the earth, and orbital eccentricity, fluctuating over a range 2 1/2 times that of the earth, could produce an important climate-driving cycle. Mathematical models of the Martian surface and atmosphere based on Viking data suggest that escaped CO2 could create a surface pressure of 1-3 bars. Other factors such as the effect of continental drift, the increased brightness of the sun, and planetary reversals of magnetic field polarity are discussed, and the questions of where Martian water and CO2 have gone are considered

229

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

230

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

231

ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT - PHYSICAL REMOVAL OF MICROBIOLOGICAL AND PARTICULATE CONTAMINANTS IN DRINKING WATER : SEPARMATIC? FLUID SYSTEMS DIATOMACEOUS EARTH PRESSURE TYPE FILTER SYSTEM MODEL 12P-2  

Science.gov (United States)

The verification test of the SeparmaticTM DE Pressure Type Filter System Model 12P-2 was conducted at the UNH Water Treatment Technology Assistance Center (WTTAC) in Durham, New Hampshire. The source water was finished water from the Arthur Rollins Treatment Plant that was pretr...

232

High-pressure phases and transitions of the layered alkaline earth nitridosilicates SrSiN2 and BaSiN2  

International Nuclear Information System (INIS)

We investigate the high-pressure phase diagram of SrSiN2 and BaSiN2 with density-functional calculation. Searching a manifold of possible candidate structures, we propose new structural modifications of SrSiN2 and BaSiN2 attainable in high-pressure experiments. The monoclinic ground state of SrSiN2 transforms at 3 GPa into an orthorhombic BaSiN2 type. At 14 GPa a CaSiN2-type structure becomes the most stable configuration of SrSiN2. A hitherto unknown Pbcm modification is adopted at 85 GPa and, finally, at 131 GPa a LiFeO2-type structure. The higher homologue BaSiN2 transforms to a CaSiN2 type at 41 GPa and further to a Pbcm modification at 105 GPa. Both systems follow the pressure-coordination rule: the coordination environment of Si increases from tetrahedral through trigonal bipyramidal to octahedral. Some high-pressure phases are related in structure through simple group-subgroup mechanisms, indicating displacive phase transformations with low activation barriers.

233

A hypothesis of earth quake  

CERN Document Server

Without a model, it is impossible for a geophysicist to study the possibility of forecasting earth quakes. In order to make a simple model, we make a hypothesis of earth quakes. The hypothesis is: (i) There are two kinds of earth quakes, one is the triggered breaking (earth quake), the other is spontaneous breaking (earth quake). (ii) Most major quakes in continental plates Eurasian Plate, North America Plate, South America Plate, Africa Plate and Australia Plate are triggered breaking. (iii) These triggered quakes are triggered by the movements of high pressure centers and low pressure centers of the atmosphere on continental plates. (iv) How can the movements of the high pressure centers trigger a quake? It depends on the extent of the high pressure center and the speed of the movement. Here, we stress high pressure center instead of low pressure center because it is dominated by high pressure center mostly. Of course, the boundary of the plates must have stored enough energy to have quakes, that is, near t...

Tsai, Yeong-Shyeong

2008-01-01

234

Water and sodium balance in space  

DEFF Research Database (Denmark)

We have previously shown that fluid balances and body fluid regulation in microgravity (microG) differ from those on Earth (Drummer et al, Eur J Physiol 441:R66-R72, 2000). Arriving in microG leads to a redistribution of body fluid-composed of a shift of fluid to the upper part of the body and an exaggerated extravasation very early in-flight. The mechanisms for the increased vascular permeability are not known. Evaporation, oral hydration, and urinary fluid excretion, the major components of water balance, are generally diminished during space flight compared with conditions on Earth. Nevertheless, cumulative water balance and total body water content are stable during flight if hydration, nutritional energy supply, and protection of muscle mass are at an acceptable level. Recent water balance data disclose that the phenomenon of an absolute water loss during space flight, which has often been reported in the past, is not a consequence of the variable microG. The handling of sodium, however, is considerably affected by microG. Sodium-retaining endocrine systems, such as renin-aldosterone and catecholamines, are much more activated during microG than on Earth. Despite a comparable oral sodium supply, urinary sodium excretion is diminished and a considerable amount of sodium is retained-without accumulating in the intravascular space. An enormous storage capacity for sodium in the extravascular space and a mechanism that allows the dissociation between water and sodium handling likely contribute to the fluid balance adaptation in weightlessness.

Drummer, C; Norsk, P

2001-01-01

235

A Question of Balance  

Science.gov (United States)

Most authorities consider balance to be a component of skill-related physical fitness. Balance, however, is directly related to health, especially for older adults. Falls are a leading cause of injury and death among the elderly. Improved balance can help reduce falls and contribute to older people remaining physically active. Balance is a…

Claxton, David B.; Troy, Maridy; Dupree, Sarah

2006-01-01

236

Functional balance tests  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background and Aim: All activities of daily living need to balance control in static and dynamic movements. In recent years, a numerous increase can be seen in the functional balance assessment tools. Functional balance tests emphasize on static and dynamic balance, balance in weight transfer, the equilibrium response to the imbalances, and functional mobility. These standardized and available tests assess performance and require minimal or no equipment and short time to run. Functional balan...

Parvin Raji

2012-01-01

237

Earth Floor  

Science.gov (United States)

This Classroom of the Future (COTF) website highlights information about the Earth and its development through time. Spheres discusses layers of the Earth's environment such as the hydrosphere, Cycles discusses rock and water cycles, and Diversity illustrates different species and genetic variations that have emerged on Earth. Also covered are biomes, adaptation, geologic time, and plate tectonics. Each of these sections is an in-depth tutorial on these specific topics.

238

Visible Earth  

Science.gov (United States)

NASA's Visible Earth is a searchable directory of images, visualizations, and animations of the Earth. The images are also listed under the following categories: agriculture, atmosphere, biosphere, cryosphere, human dimensions, hydrosphere, land surface, oceans, radiance or imagery, solid earth, locations, and satellites. Accompanying each image are credits, data about the image, the satellite it was taken from, a description of what is shown, and a high-resolution viewable image.

239

Earth Day  

Science.gov (United States)

On April 22, 2005, people around the world will celebrate the 35th anniversary of Earth Day. This Topic in Depth focuses on the past and present of this significant day. From the Wisconsin Historical Society, the first two sites contain historical documents pertaining to Earth Day. The first (1) document features a May 1970 issue of The Gaylord Nelson Newsletter reporting on the first Earth Day. The second (2) document is a speech by Nelson entitled "An Environmental Agenda for the 70's." Housed in the archives of the US Environmental Protection Agency (EPA) website, the next two sites also contain historical documents. The first (3) site contains an article written by Nelson for the EPA Journal in April of 1980, entitled "Earth Day '70: What It Meant." The second (4) site contains an article written by John C. Whitaker (former Interior undersecretary in the Nixon administration) for the EPA Journal in the summer of 1998. The article is entitled "Earth Day Recollections: What It Was Like When the Movement Took Off." The (5) Earth Day Network (first mentioned in the April 4, 2003, Scout Report for Life Sciences) works "to broaden the environmental movement worldwide and to educate and mobilize people, governments, and corporations to take responsibility for a clean and healthy environment." In addition to information sections about Ongoing Programs, Current Campaigns, and News, the Earth Day Network website contains Earth Day 2005 Materials for organizers. From EarthDay.gov, Take Action In Your Classroom (6) offers links to a variety of environmental education resources. The next website, from the U.S. Army Environmental Center, presents (7) Army Earth Day; and links to information about the Army's environmental activities. The final (8) site is an Earth Day-inspired educational website (first reported on in the April 14, 1999 Scout Report for Science & Engineering) from the Wilderness Society. The site offers a collection of environmental education resources for teachers and students. [NL

240

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

 
 
 
 
241

Social Balance Theory  

CERN Document Server

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 the global balance structure. Several experiments are done and we discover how the social group can form separation of subgroups in a group or strengthening a social group while emphasizing the structure theorem and social mitosis previously introduced.

Khanafiah, D; Khanafiah, Deni; Situngkir, Hokky

2004-01-01

242

Mineral solubilities in aqueous fluids at high pressures and temperatures: New thermodynamic model and implications for mass transfer in the Earth's crust and mantle  

Science.gov (United States)

Aqueous fluids are produced by metamorphic devolatilization and magmatic activity in a variety of settings including continental orogens, subduction zones with magmatic arcs as well as oceanic ridges and sea floor. They are responsible for mobility and transport of inorganic and organic solutes as manifested by alteration or veining, distinct element depletion-enrichment patterns or isotopic disturbances. The impact of many fluid-mediated processes is promoted by high time-integrated fluid fluxes, 101-106 m3 m-2, inferred for diffuse and focused fluid flow through lithosphere. Previous approaches to aqueous speciation have almost exclusively been based on the Helgeson-Kirkham-Flowers equation of state, which, however, suffers from inaccuracies in the vicinity of critical point of water and cannot be extrapolated to very high temperatures and pressures due to the lack of experimental data on dielectric constant of H2O. We propose a new thermodynamic model for dissolution of minerals in aqueous fluids at high temperatures and pressures, which is derived from individual energetic contributions to lattice breakdown, solute hydration and compression of the hydration shell. The thermodynamic properties depend on temperature and H2O density only and are calculated using three to five model parameters calibrated by experimental data. Our formulation of the density dependence has the advantage of behaving as a smooth function at the critical point of H2O, it closely corresponds to the generalized Krichevskii parameter, and it linearly correlates with the Born electrostatic energy. Solubilities of quartz, corundum, rutile, calcite, apatite, fluorite, and portlandite monotonously increase for a given phase by 4-5 orders of magnitude as temperature rises from 200 to 1100 oC along typical geotherms. At constant pressure, however, mineral solubilities initially increase with rising temperature, but subsequently drop. This effect results from a reversal in isobaric expansivity of the aqueous solvent and it is proportional to the charge of solute species. Oxide minerals such as quartz, corundum and rutile dissolve in pure H2O as predominantly neutral species. Consequently, their solubility behavior shows little dependence on solvent properties and their retrograde solubilities are limited to pressures below 1.3 kbar. The Ca-bearing phases (calcite, fluorite, apatite and portlandite), by contrast, dissolve to variably charged species, and the electrostriction effects become more significant. The solubilities of these minerals still decrease at medium and high metamorphic grades and over wide range of pressures. Application of transport theory to our thermodynamic model permits calculation of time-integrated fluid fluxes needed to precipitate mineral veins during metamorphic events. The integrated fluid fluxes along geotherms of 20 and 7 oC km-1 vary from 104 to 1015 m3 m-2. Quartz and calcite require the lowest fluid fluxes, and this is in broad agreement with observations of high mobility and veining of these minerals in many metamorphic environments. Conversely, typical integrated fluid fluxes in crustal shear zones predict transfer of quartz and calcite in quantities of several to tens vol. % whereas the mobility of apatite or rutile lies below 1000 ppm. Although less important for the major element metasomatism, such a transfer may substantially affect trace element budget in metasomatized rocks.

Dolejš, David; Manning, Craig E.

2010-05-01

243

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

244

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

245

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

Science.gov (United States)

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.

Zibrov, Igor P.; Filonenko, Vladimir P.; Zakharov, Nikolai D.; Werner, Peter; Drobot, Dmitrii V.; Nikishina, Elena E.; Lebedeva, Elena N.

2013-07-01

246

30 CFR 817.57 - Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams.  

Science.gov (United States)

... 2010-07-01 false Hydrologic balance: Surface activities in or adjacent...ACTIVITIES § 817.57 Hydrologic balance: Surface activities in or adjacent...g) of this chapter and that earth materials, ground-water discharges, and...

2010-07-01

247

Balance (or Vestibular) Rehabilitation  

Science.gov (United States)

... Information Series [PDF]. When should I see an audiologist? Audiologists perform audiologic and balance assessment in order to ... how to treat your dizziness and balance difficulties. Audiologists can give you information to increase your understanding ...

248

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

249

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

250

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

251

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

252

Accretion and Core-Mantle Differentiation of the Earth and Other Terrestrial Planets  

Science.gov (United States)

Using a multi-stage core-mantle differentiation model that incorporates over 250 Grand Tack N-body simulations, we have studied the growth of the Earth’s mantle and core as well as those of Mars, Venus and the embryos, which impacted the Earth (i.e. the proto-lunar impactor Theia). The Grand Tack is the terrestrial planet formation scenario that most successfully matches dynamic and simple compositional constraints. During this scenario, Jupiter and Saturn migrate inwards and then outwards through the inner Solar System. The Earth grows due to the accretion of planetesimals and embryos from throughout the inner disk and from a disk of planetesimals exterior to Jupiter and Saturn, which are scattered inward by their migration. The core-mantle differentiation model uses chemical mass balance and metal-silicate element partitioning data to determine the mantle and core compositions as the Earth grows. Treating the initial oxidation state of the original bodies as free parameters, taking the composition of the Earth’s primitive mantle as a constraint, and assuming that the non-volatile elements are present in Solar System (CI) relative abundances, we use least squares refinement to fit the metal-silicate equilibration pressure, the disequilibrium fraction of projectile cores and 4 parameters defining an initial oxidation gradient in the inner Solar System. Consistent with the Grand Tack scenario’s explanation of the C-type asteroids originating from the outer Solar System, water is delivered from only these bodies. We find that that the accreting Earth evolves in time—accreting increasingly oxidized material and changing the oxidation state of the Earth’s mantle, and that the metal-silicate equilibration pressures are about 60-70% of the core-mantle boundary pressures and nearly all of the metal in each projectile core equilibrates with the some portion of the planet’s silicate mantle. The best fits are found when the planetesimals and embryos closest to the Sun are highly reduced and those further out are increasingly oxidized. Venus is found to be very similar to the Earth, and the FeO content of the Martian mantle depends critically on the location of the original location of its stranded embryo nucleus.

Jacobson, Seth A.; Rubie, David C.; Morbidelli, Alessandro; O'Brien, David P.; Young, Edward D.; de Vries, Jellie; Nimmo, Francis; Palme, Herbert; Frost, Dan J.

2014-11-01

253

Mass balance, meteorological, and runoff measurements at South Cascade Glacier, Washington, 1992 balance year  

Science.gov (United States)

Values of winter snow accumulation and summer snow, firn, and ice ablation were measured at South Cascade Glacier, WA, to determine the winter and net balance for the 1992 balance year. The 1992 winter balance, averaged over the glacier, was 1.91 m, and the net balance was -2.01 m. This extremely negative balance continued a trend of negative balance years beginning in 1977. Air temperature (at 1,615 m and 1,867 m), barometric pressure, precipitation, and runoff from this glacier basin and an adjacent non-glacierized basin were also continuously measured. This report makes all these data, in tabular, graphical, and machine-readable forms, available to users.

Krimmel, R. M.

1993-01-01

254

The Earth  

Science.gov (United States)

This lesson covers the interior of the Earth, geological differentiation, plate tectonics, composition and layers of the atmosphere, weather and climate, consequences of rotation for weather, the magnetic field, magnetosphere and Van Allen Radiation Belts of Earth, auroras (Northern and Southern Lights, and imaging the Earth. There is information on seismic waves, and convection currents; an animation of continental drift; evidence for plate tectonics, including maps of crustal plate boundaries and the age of the sea floor crustal plates; and explanations of solar heating, Coriolis forces, cyclones and anticyclones.

2007-06-17

255

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

256

Keeping in Balance  

Science.gov (United States)

In this lesson for grades 1 and 2, students record observations and look for patterns while exploring weights on a balance scale. They balance equal and unequal weights and record their distances from the fulcrum. Students use a crayon (as the fulcrum) and a ruler to represent the balance. A printable record keeping sheet is provided.

2011-01-01

257

Balance and flux  

Science.gov (United States)

Ecosystems and populations of organisms within ecosystems function by the principle of balance and flux. Balance can be thought of as a state of equilibrium, or a state of equal changes between two sides. Flux can be thought of as a rate of flow or changes. Even small changes in an ecosystem's or population's balance and flux could lead to disaster.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-16

258

Earth ionosphere  

International Nuclear Information System (INIS)

The data on the Earth ionosphere are presented in a popular form. The ionization sourcesi ionosphere structure and dynamics, ionosphere effect upon radiowave propagation are described along with the methods of ionosphere investiagtion

259

Generation of the substorm-fac by slow mode disturbances in the near Earth plasma sheet  

International Nuclear Information System (INIS)

Complete text of publication follows. The magnetospheric substorm is the fundamental but unsolved problem in the solar-terrestrial physics. In our previous studies, by using the GEOTAIL/MGF, LEP, and EPIC data, we have presented the fundamental structure of convection in the near-earth magnetotail and suggested a scenario for the behavior of near-earth plasma sheet during substorms. Observational facts obtained from these studies are summarized as follows: (1) The stress balance is primarily achieved by -grad P and J x B. This basic condition remains unchanged even in the magnetotail disturbances. (2) The diamagnetic property pertains to variation of all time scales. (3) In relatively near-earth magnetotail, -grad P is intensified for a few tens of minutes prior to the onset of magnetotail disturbances. The enhancement subsides in accordance with the development of disturbances. As for the interval of substorms, (i) during the growth phase, plasma pressure is intensified in the near-earth plasma sheet and additional earthward pressure gradient is superimposed to the background gradient. The plasma pressure peak is formed in the region less than the radial distance of 8 RE. (ii) After the onset, enhanced pressure gradient is reduced in accordance with the development of slow mode disturbances. Consequentially, the plasma stress and the Maxwell stress are reduced in the near-earth tail where they have been intensified during the growth phase. From these obser during the growth phase. From these observational facts, it is suggested that the slow mode is the primary process as the non-Alfvenic (non-convective) motion in the earth's magnetotail. The role of slow mode motion is to resolve the pressure gradient and magnetic tension along the background magnetic field. The slow mode disturbance is crucial for the redistribution of plasma fluid along the magnetic field and the reconfiguration of magnetic field. The excitation of the substorm-FAC must be explained by the energy and stress balance consistent with the above facts. In this paper, we refine the data analysis and examined in detail some substorm events. We will show the obtained results and propose its implication for the excitation of substorm-FAC.

260

Determining Atmospheric Pressure Using a Water Barometer  

Science.gov (United States)

The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

Lohrengel, C. Frederick, II; Larson, Paul R.

2012-01-01

 
 
 
 
261

Reconceptualizing balance: attributes associated with balance performance.  

Science.gov (United States)

Balance tests are commonly used to screen for impairments that put older adults at risk for falls. The purpose of this study was to determine the attributes that were associated with balance performance as measured by the Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT) balance test. This study was a cross-sectional secondary analysis of baseline data from a longitudinal cohort study, the Boston Rehabilitative Impairment Study of the Elderly (Boston RISE). Boston RISE was performed in an outpatient rehabilitation research center and evaluated Boston area primary care patients aged 65 to 96 (N=364) with self-reported difficulty or task-modification climbing a flight of stairs or walking 1/2 of a mile. The outcome measure was standing balance as measured by the FICSIT-4 balance assessment. Other measures included: self-efficacy, pain, depression, executive function, vision, sensory loss, reaction time, kyphosis, leg range of motion, trunk extensor muscle endurance, leg strength and leg velocity at peak power. Participants were 67% female, had an average age of 76.5 (±7.0) years, an average of 4.1 (±2.0) chronic conditions, and an average FICSIT-4 score of 6.7 (±2.2) out of 9. After adjusting for age and gender, attributes significantly associated with balance performance were falls self-efficacy, trunk extensor muscle endurance, sensory loss, and leg velocity at peak power. FICSIT-4 balance performance is associated with a number of behavioral and physiologic attributes, many of which are amenable to rehabilitative treatment. Our findings support a consideration of balance as multidimensional activity as proposed by the current International Classification of Functioning, Disability, and Health (ICF) model. PMID:24952097

Thomas, Julia C; Odonkor, Charles; Griffith, Laura; Holt, Nicole; Percac-Lima, Sanja; Leveille, Suzanne; Ni, Pensheng; Latham, Nancy K; Jette, Alan M; Bean, Jonathan F

2014-09-01

262

ITER - Earthing  

Energy Technology Data Exchange (ETDEWEB)

Earthing of electrical installations is mainly governed by safety rules. Electromagnetic compatibility also deals with earthing, among other circuit characteristics. Tokamaks are large-scale electrical installations that are known to generate large and low frequency magnetic fields as well as large and high frequency electric fields. Four European Tokamak installations have been investigated, from the earthing point of view, to identify appropriate techniques to earth the electrical equipment and to provide the lowest possible electromagnetic interference with the measurement circuits. But none of these existing installations looks like ITER, not even remotely. The plasma current range, the superconducting coils, the thick and continuous vacuum vessel, the cryostat, the very high voltage of its neutral beam injectors, the available amount of auxiliary heating power, the sensitivity of its magnetic measurements required for long pulses, the size of the site and the powerful supply grid all affect the plant earthing. Based on these investigations and the ITER specificities, a layout of the ITER site electrical supply grid and of the related earthing grid is proposed. Basic rules to reduce the electromagnetic noise at its sources and to improve the measurement immunity are also suggested.

Perez, Albert, E-mail: albert.perez@epfl.ch [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confederation Suisse, CH-1015 Lausanne (Switzerland); Fasel, Damien; Lister, Jonathan; Marletaz, Blaise; Marmillod, Philippe; Siravo, Ugo [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas (CRPP), Association EURATOM-Confederation Suisse, CH-1015 Lausanne (Switzerland)

2011-10-15

263

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

264

How Our Balance System Works  

Science.gov (United States)

How Our Balance System Works Balance and equilibrium help us stay upright when standing and know where we are in relation ... acceleration (such as going up in an elevator). Balance Testing Balance system assessment is often recommended when ...

265

Functional balance tests  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Aim: All activities of daily living need to balance control in static and dynamic movements. In recent years, a numerous increase can be seen in the functional balance assessment tools. Functional balance tests emphasize on static and dynamic balance, balance in weight transfer, the equilibrium response to the imbalances, and functional mobility. These standardized and available tests assess performance and require minimal or no equipment and short time to run. Functional balance is prerequisite for the most static and dynamic activities in daily life and needs sufficient interaction between sensory and motor systems. According to the critical role of balance in everyday life, and wide application of functional balance tests in the diagnosis and assessment of patients, a review of the functional balance tests was performed.Methods: The Google Scholar, PubMed, Science Direct, Scopus, Magiran, Iran Medex, and IranDoc databases were reviewed and the reliable and valid tests which were mostly used by Iranian researchers were assessed.Conclusion: It seems that Berg balance scale (BBS have been studied by Iranian and foreign researches more than the other tests. This test has high reliability and validity in elderly and in the most neurological disorders.

Parvin Raji

2012-12-01

266

Magnetohydrodynamic Modeling of Space Plasmas with Pressure Anisotropy  

Science.gov (United States)

The present generation of global 3D magnetohydrodynamic (MHD) simulations of the Sun-Earth environment is based on the assumption that the plasma pressure is isotropic. This assumption, however, is an inadequate description of space plasmas, such as plasmas in the Earth's magnetosheath and inner magnetosphere, as well as in the solar corona, where strong magnetic fields give rise to highly anisotropic plasma pressures. Specifically, particle collisions are not frequent enough to balance the particle motions along and perpendicular to the magnetic field, thus the corresponding parallel and perpendicular pressure components are different. This dissertation research, therefore focuses on extending the University of Michigan MHD space physics code BATS-R-US to account for pressure anisotropy. The analytical model is developed by studying the formulation of anisotropic MHD under both classical and semirelativistic approximations, in particular, deriving the dispersion relation and characteristic wave speeds for semirelativistic anisotropic MHD. The software implementation of the new model, Anisotropic BATS-R-US, is verified through numerical tests. Several applications of Anisotropic BATS-R-US are considered in this work. The first application is to simulate the quiet time terrestrial magnetosphere and validate the results with satellite measurements. Pressure anisotropy is found to widen the magnetosheath, enhance the nightside plasma pressure, and reduce the flow speed in the magnetotail. In the second application, Anisotropic BATS-R-US is coupled with two ring current models, respectively, to conduct global magnetospheric simulations during geomagnetic disturbed times. The simulation results indicate the importance of pressure anisotropy in controlling the nightside magnetic field topology. Finally, Anisotropic BATS-R-US is applied to simulate the solar corona and heliosphere, in which pressure anisotropy results in faster solar wind speeds close to the Sun. This application has the potential to capture the anisotropic heating mechanism that has not been addressed by isotropic MHD models.

Meng, Xing

267

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

268

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

269

Maintaining the Balance  

Science.gov (United States)

In this lesson for grades 3, 4 and 5, students participate in activities in which they focus on patterns and relations that can be developed from the exploration of balance, mass, length of the mass arm, and the position of the fulcrum. The focus of this lesson is determining the position necessary to balance uneven objects and the effect on balance of moving the fulcrum. Printable activity sheets, ideas for implementation and extension are included.

2011-01-01

270

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

271

The Influence of the Atmospheric Transmission for the Solar Radiation and Earth’s Surface Radiation on the Earth’s Climate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The physical and mathematical model of the planetary heat balance is developed to establish the influence of the atmospheric transmission for the solar radiation in the shortwave spectrum range and for the surface IR radiation in the longwave spectrum range on the Earth’s climate. It is shown the possibility of the decreas- ing of the atmospheric and surface temperatures with the decreasing of the atmospheric transmission for IR spectrum range, and this decreasing can’t be equilibrated wi...

Bogoyavlenskii, Alexander I.; Abdussamatov, Habibullo I.; Khankov, Sergey I.; Lapovok, Yevgeniy V.

2010-01-01

272

Spaceship Earth  

Science.gov (United States)

In this lesson, from Science NetLinks, students will develop an understanding of our planet as a system by designing a very-long-duration space mission in which the life-support system is patterned after that of earth.

Science Netlinks;

2002-09-10

273

A Balance of Power?  

Science.gov (United States)

The booming economy of the Pacific Northwest region promotes the dilemma of balancing the need for increased electrical power with the desire to maintain that region's unspoiled natural environment. Pertinent factors discussed within the balance equation are population trends, economic considerations, industrial power requirements, and…

Mosey, Edward

1991-01-01

274

Mobility Balance Sheet 2009  

International Nuclear Information System (INIS)

The Mobility Balance Sheet provides an overview of the state of the art of mobility in the Netherlands. In addition to describing the development of mobility this report also provides explanations for the growth of passenger and freight transport. Moreover, the Mobility Balance Sheet also focuses on a topical theme: the effects of economic crises on mobility.

275

Pan Balance - Shapes  

Science.gov (United States)

This resource provides a virtual manipulative pan balance to explore and practice equality with geometric shapes. Each shape is assigned a certain weight. The pictorial representation is entered in a table and the items on each side of the balance can be represented by an algebraic expression.

Mathematics, Illuminations N.

2009-03-04

276

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

277

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

278

Impact: Earth!  

Science.gov (United States)

What would happen if a large meteorite or other object hit the Earth? It's something that has engaged the minds and talents of astrophysicists (and students of all ages) for decades. Now the generally curious can create their own simulated impact with Purdue University's "Impact Earth" website. Visitors can browse the Famous Craters area to get started. This part includes some "classics," such as the Ries Crater and the Tunguska Fireball. Of course, visitors really must use the handy interface to craft their own impact, projectile, and target parameters to get the full effect on how such an event plays out. Also, the site includes a complete Documentation file (a peer-reviewed article) and a detailed glossary.

2013-01-01

279

Earth Lab  

Science.gov (United States)

Earth Lab is a database of fossils, minerals and rocks from the UK. A photograph is displayed for each specimen selected, as well as the scientific name, location and properties or age of the specimen. The fossils can be searched by area, age, and group; minerals by area, element, group, and property; and rocks by area, geological age, and type of rock. A series of questions allows users to identify their own specimens.

280

Air Under Pressure  

Science.gov (United States)

Students are introduced to air masses, with an emphasis on the differences between and characteristics of high- versus low-pressure air systems. Students explore actual data by comparing maps of high- and low-pressure air masses to radar data showing where weather is occurring. Students also hear about weather forecasting instrumentation and how engineers work to improve these instruments for atmospheric measurements on Earth and in space.

Integrated Teaching And Learning Program

 
 
 
 
281

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.

282

Un-Earth-Like Interiors of Earth-Like Exoplanets  

Science.gov (United States)

Plate tectonics has played key roles in forming/modifying the surface environment of the Earth. Geophysical studies have shown that plate tectonics is linked to deep processes in the Earth and likely driven by convection in the deep mantle. Recent astrophysical survey (Bond et al., 2010) has shown large variations in key elemental ratios (such as Mg/Si) for planetary host stars. As Earth-like exoplanets may have the rocky mantles, composed mainly of magnesium silicates similar to the Earth, Mg/Si is of particular interest to understand the structure and dynamics of the solid parts of these exoplanets. The astrophysical data suggest that Mg/Si can vary between ~0.8 and ~2. Rocky exoplanets with Mg/Si~2 will have the mantles made almost entirely of olivine (Mg2SiO4) and its high-pressure polymorphs, while the mantles of rocky exoplanets with Mg/Si~1 will be made mostly of pyroxene (MgSiO3) and its high pressure polymorphs. The variation in mineralogy is significant considering that Earth's upper mantle is made of ~60% olivine and ~40% pyroxene. While the variation in mineralogy would not change the densities of the Earth-like exoplanets more than ~3%, it has profound consequences for the structure and convection in the mantle. For example, some rocky exoplanets with high Mg/Si may develop much more extensive melting at shallower depths in the mantle, resulting in different compositions and structures for their crusts compared with the Earth. In the opposite, extensive melting in some rocky exoplanets with low Mg/Si may be limited to the deep mantle. In Earth's mantle, high-pressure polymorphs of olivine and pyroxene undergo phase transitions to dense magnesium silicates and oxides in the lower mantle (~70% perovskite, MgSiO3, and ~30% periclase, MgO) at 660-km depth (Shim et al., 2001). Due to the high viscosity of MgSiO3 perovskite, the viscosity of the lower mantle is two orders of magnitude higher than the upper mantle in the Earth, affecting convection and chemical mixing. Because the viscosity of periclase (MgO) is much lower than perovskite (Ammann et al., 2011), some rocky exoplanets with high Mg/Si will have rheology of their lower mantles dominated by periclase, leading to much more vigorous convection in their mantles. These few examples suggest that variations in elemental abundances in rocky exoplanets can lead to very different compositions and processes in the solid part of the exoplanets, even if their densities are very similar to that of the Earth.

Shim, S.-H. D.

2014-03-01

283

Active balance system and vibration balanced machine  

Science.gov (United States)

An active balance system is provided for counterbalancing vibrations of an axially reciprocating machine. The balance system includes a support member, a flexure assembly, a counterbalance mass, and a linear motor or an actuator. The support member is configured for attachment to the machine. The flexure assembly includes at least one flat spring having connections along a central portion and an outer peripheral portion. One of the central portion and the outer peripheral portion is fixedly mounted to the support member. The counterbalance mass is fixedly carried by the flexure assembly along another of the central portion and the outer peripheral portion. The linear motor has one of a stator and a mover fixedly mounted to the support member and another of the stator and the mover fixedly mounted to the counterbalance mass. The linear motor is operative to axially reciprocate the counterbalance mass.

Qiu, Songgang (Inventor); Augenblick, John E. (Inventor); Peterson, Allen A. (Inventor); White, Maurice A. (Inventor)

2005-01-01

284

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

285

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

286

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.

287

Are You Balanced?  

Science.gov (United States)

One of the most basic money management skills that everyone needs to know is how to maintain and balance (reconcile) their checkbook. Why then are there so many people who don\\'t know how? If your business math skills are a little rusty, you might want to visit this web site for a little practice. Business Math Practice To get started, read the following two articles on balancing your checkbook. Step-by-Step Financial Basics Did you find the actual balancing process a little hard to follow? ...

Gordon, Mr.

2006-10-20

288

Earth Observation Plan Focuses on User Needs and Measurements  

Science.gov (United States)

The White House's new U.S. National Plan for Civil Earth Observations focuses on user needs and measurements while defining a framework for constructing a balanced portfolio of Earth observations and observing systems, officials with the White House Office of Science and Technology Policy (OSTP) said at a 4 September forum about the plan.

Showstack, Randy

2014-09-01

289

Greenland Ice Sheet Mass Balance  

Science.gov (United States)

Mass balance equation for glaciers; areal distribution and ice volumes; estimates of actual mass balance; loss by calving of icebergs; hydrological budget for Greenland; and temporal variations of Greenland mass balance are examined.

Reeh, N.

1984-01-01

290

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 ...

291

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 ...

292

[Buprenorphine in balanced anesthesia].  

Science.gov (United States)

Buprenorphine was administered for the balanced general anaesthesia in 300 patients during several operations. The results obtained, the good features of analgesia, morphine-like, the absence of cardiovascular and respiratory side effects are presented. PMID:2633073

Di Noto, M; Morgana, G; Piccolo, G; Proietti, L

1989-10-01

293

National energy balance 1989  

International Nuclear Information System (INIS)

The national energy balance of 1989 presents data about energy production, energy consumption and external energy dependence. The composition of sectorial consumption in the different energetic group are also included. (author)

294

Fluid and Electrolyte Balance  

Science.gov (United States)

... They are in your blood, urine and body fluids. Maintaining the right balance of electrolytes helps your ... them from the foods you eat and the fluids you drink. Levels of electrolytes in your body ...

295

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.)

296

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.)

297

Global Energy Balance  

Science.gov (United States)

A simple click-through animation from Scripps Institute's Earthguide program breaks the complex topic of the global energy balance into separate concepts. Slides describe the different pathways for incoming and outgoing radiation.

Oceanography, Scripps I.

298

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.

299

Energy balances 2000  

International Nuclear Information System (INIS)

The energy balances of the Danish Statistical Office are the designation of the goods balances, which are tabulated for each energy article in both physical entities (quantities) and in base rates (values). The balance concept is connected to the definition supply = use, which is the basis for the construction of the system. The supply is determined as the sum of two items: import and production while the total use is the sum of 138 items: export, waste and transmission loss, stock increase, input in lack of the 130 industries, and private consumption divided into 5 consumption groups. The statistical analysis is performed yearly in both quantities and values for 35 energy articles. Values are computed for base rates, profits, taxes, VAT and market prices (buyer's price), respectively. The energy balances from 1975 to 2000 are presented for comparison. (EHS)

300

Human Balance System  

Science.gov (United States)

... the coordination center of the brain) and the cerebral cortex (the thinking and memory center). The cerebellum provides ... balance control during that movement. Contributions from the cerebral cortex include previously learned information; for example, because icy ...

 
 
 
 
301

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

302

Pan Balance-Numbers  

Science.gov (United States)

This Java tool is used to strengthen student understanding of equality and computation of numerical expressions. The applet also helps students understand that equality is a relationship, not an operation. After entering an expression in both the red and blue pan, the pans will move up and down depending on which expression is greater. When the expressions are equivalent, the pans will balance and the full equation will be entered into the Balanced Equations table. Instructions and exploration directions and questions are included.

2011-01-01

303

Earth Gauge  

Science.gov (United States)

Earth Gauge is a free environmental information service for broadcast meteorologists in major U.S. media markets, based on the 3-5 day forecast. The service is designed to make it easy to talk about the links between weather and the environment on-air with simple "factoids" and viewer action tips. Teachers or students can browse an index of weather conditions, environmental impacts, and viewer action tips for many locations, organized by city, weather type, or environmental topic. There are also links to additional resources, including fact sheets and special features, imagery, video clips, and others.

304

Earth 911  

Science.gov (United States)

Earth 911 is an organization focused on empowering the public with community-specific resources to improve their quality of life. To accomplish this goal, they provide information on a wide range of environmental topics including recycling (several types of materials), household hazardous waste, water quality, composting, air pollution prevention, fire prevention, green shopping tips, and mercury pollution. Environmental news links, games and activities for kids, and local news and events are also included. Users may enter a zip code to obtain information on environmental issues specific to where they live.

2004-01-01

305

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

306

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

307

Assessment of the Hf-N, Zr-N and Ti-N phase diagrams at high pressures and temperatures: balancing between MN and M3N4 (M = Hf, Zr, Ti)  

International Nuclear Information System (INIS)

We study the nitrogen-rich part of the phase diagram Hf-N, Zr-N and Ti-N, employing first-principle calculations for an assessment of energy and enthalpy as a function of pressure. At zero pressure the novel cubic Th3P4-type structures are metastable modifications of M3N4 (M = Hf,Zr). The lowest energy configuration of both compounds is an orthorhombic Zr3N4-type. This orthorhombic structure will transform into the Th3P4-type at 9 and 6 GPa, for Hf3N4 and Zr3N4, respectively. The lowest energy configuration of Ti3N4 is a CaTi2O4-type structure. It will first transform into the orthorhombic Zr3N4-type at 3.8 GPa, then further transform into the cubic Th3P4-type at 15 GPa. The spinel type is metastable throughout the phase diagram for all three systems. The phase boundary between mononitrides MN and the M3N4-phases is accessed as a function of pressure. We include the entropy of gaseous nitrogen from tabulated data to estimate the free enthalpy ?G of the nitride phases. The orthorhombic modification of Hf3N4 turns out to be thermodynamically stable with respect to a decomposition into the mononitrides and nitrogen for temperatures up to about 1000 deg. C. The stability of Zr3N4 is in quesof Zr3N4 is in question; within the estimated error no final conclusion can be drawn. Ti3N4, on the other hand, will only be metastable. At higher pressures, however, the free energy of nitrogen is substantially reduced and the 3:4 compositions become more stable. We reproduce the experimental requirements (18 GPa and 2800 K) for the synthesis of the novel Hf3N4. At 2800 K the pressures needed to synthesize cubic phases of Zr3N4 and Ti3N4 are estimated to be 40 and 100 GPa, respectively

308

Global analysis of river systems: from Earth system controls to Anthropocene syndromes.  

Science.gov (United States)

Continental aquatic systems from rivers to the coastal zone are considered within two perspectives: (i) as a major link between the atmosphere, pedosphere, biosphere and oceans within the Earth system with its Holocene dynamics, and (ii) as water and aquatic biota resources progressively used and transformed by humans. Human pressures have now reached a state where the continental aquatic systems can no longer be considered as being controlled by only Earth system processes, thus defining a new era, the Anthropocene. Riverine changes, now observed at the global scale, are described through a first set of syndromes (flood regulation, fragmentation, sediment imbalance, neo-arheism, salinization, chemical contamination, acidification, eutrophication and microbial contamination) with their related causes and symptoms. These syndromes have direct influences on water uses, either positive or negative. They also modify some Earth system key functions such as sediment, water, nutrient and carbon balances, greenhouse gas emissions and aquatic biodiversity. Evolution of river syndromes over the past 2000 years is complex: it depends upon the stages of regional human development and on natural conditions, as illustrated here for the chemical contamination syndrome. River damming, eutrophication and generalized decrease of river flow due to irrigation are some of the other global features of river changes. Future management of river systems should also consider these long-term impacts on the Earth system. PMID:14728790

Meybeck, Michel

2003-12-29

309

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

310

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

311

Synthesis of rare earth monoxides  

International Nuclear Information System (INIS)

The standard Gibbs energy changes for the formation of an ionic or metallic monoxide from rare earth metal and sesquioxide have been calculated. Under high pressures ionic ytterbium monoxide and lighter rare earth metallic monoxides should be obtained, which is confirmed by experiments in a belt-type apparatus in the range 15 to 80 kbar and 500-12000C. For Ln = La, Ce, Pr, Nd, Sm, a face-centered cubic compound is obtained from each reaction. The cell parameters are respectively 5.144, 5.089, 5.031, 4.994, and 4.943 +- 0.005 A. The compounds appear golden yellow with a metallic luster. From chemical analyses and cell parameter consideration it is concluded that these compounds are the rare earth monoxides. For Ln = Gd, Dy, Tm, no reaction is observed at 50 kbar and 10000C. The rare earth monoxides show a variety of properties: LaO, CeO, PrO, and NdO are metallic with the rare earth in the trivalent state; EuO and YbO are semiconductors with the rare earth in the divalent state; SmO is metallic with samarium in an intermediate valence state close to 3

312

Synchrotron radiation - Applications in the earth sciences  

Science.gov (United States)

Synchrotron-radiation sources and their characteristics are overviewed along with recent synchrotron-based research on earth materials and future earth-science applications utilizing the next generation of synchrotron-radiation sources presently under construction. Focus is placed on X-ray scattering studies of earth materials (crystalline and noncrystalline) under ambient conditions, diffraction studies of earth materials at high pressures and/or temperatures, spectroscopic studies, primarily X-ray absorption spectroscopy, and spatially resolved X-ray fluorescence studies of compositional variations in earth materials. It is noted that other synchrotron-based methods, such as X-ray tomography and topography may become important in characterizing earth materials, while soft X-ray/vacuum ultraviolet radiation from synchrotron sources can be applied to problems involving the structural environments of low-atomic-number elements and the characterization of surface reactions of minerals with liquids and gases.

Bassett, W. A.; Brown, G. E., Jr.

1990-01-01

313

Earth Pulse  

Science.gov (United States)

Earth Pulse is the National Geographic site for conservation. It features a set of links to National Geographic sites with a variety of conservation themes such as oceans, climate, energy, fresh water, and others. Many of these pages feature interactive tours or videos. Virtual Worlds is a set of interactive tours of various environments, from the rain forest at night to a new urbanist neighborhood. There is also a collection of Sights and Sounds interactive pages on a variety of ecosystems, in which users can click on a map and see information on wildlife that inhabits the selected region. There are also links to news articles and online expeditions in which users can follow actual expeditions as they were conducted by explorers-in-residence.

2007-12-12

314

Sport-specific balance.  

Science.gov (United States)

This review includes the latest findings based on experimental studies addressing sport-specific balance, an area of research that has grown dramatically in recent years. The main objectives of this work were to investigate the postural sway response to different forms of exercise under laboratory and sport-specific conditions, to examine how this effect can vary with expertise, and to provide examples of the association of impaired balance with sport performance and/or increasing risk of injury. In doing so, sports where body balance is one of the limiting factors of performance were analyzed. While there are no significant differences in postural stability between athletes of different specializations and physically active individuals during standing in a standard upright position (e.g., bipedal stance), they have a better ability to maintain balance in specific conditions (e.g., while standing on a narrow area of support). Differences in magnitude of balance impairment after specific exercises (rebound jumps, repeated rotations, etc.) and mainly in speed of its readjustment to baseline are also observed. Besides some evidence on an association of greater postural sway with the increasing risk of injuries, there are many myths related to the negative influence of impaired balance on sport performance. Though this may be true for shooting or archery, findings have shown that in many other sports, highly skilled athletes are able to perform successfully in spite of increased postural sway. These findings may contribute to better understanding of the postural control system under various performance requirements. It may provide useful knowledge for designing training programs for specific sports. PMID:24293269

Zemková, Erika

2014-05-01

315

Balanced Flow Metering and Conditioning: Technology for Fluid Systems  

Science.gov (United States)

Revolutionary new technology that creates balanced conditions across the face of a multi-hole orifice plate has been developed, patented and exclusively licensed for commercialization. This balanced flow technology simultaneously measures mass flow rate, volumetric flow rate, and fluid density with little or no straight pipe run requirements. Initially, the balanced plate was a drop in replacement for a traditional orifice plate, but testing revealed substantially better performance as compared to the orifice plate such as, 10 times better accuracy, 2 times faster (shorter distance) pressure recovery, 15 times less acoustic noise energy generation, and 2.5 times less permanent pressure loss. During 2004 testing at MSFC, testing revealed several configurations of the balanced flow meter that match the accuracy of Venturi meters while having only slightly more permanent pressure loss. However, the balanced meter only requires a 0.25 inch plate and has no upstream or downstream straight pipe requirements. As a fluid conditioning device, the fluid usually reaches fully developed flow within 1 pipe diameter of the balanced conditioning plate. This paper will describe the basic balanced flow metering technology, provide performance details generated by testing to date and provide implementation details along with calculations required for differing degrees of flow metering accuracy.

Kelley, Anthony R.

2006-01-01

316

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.)

317

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

318

Multidimensional spectral load balancing  

Energy Technology Data Exchange (ETDEWEB)

We describe an algorithm for the static load balancing of scientific computations that generalizes and improves upon spectral bisection. Through a novel use of multiple eigenvectors, our new spectral algorithm can divide a computation into 4 or 8 pieces at once. These multidimensional spectral partitioning algorithms generate balanced partitions that have lower communication overhead and are less expensive to compute than those produced by spectral bisection. In addition, they automatically work to minimize message contention on a hypercube or mesh architecture. These spectral partitions are further improved by a multidimensional generalization of the Kernighan-Lin graph partitioning algorithm. Results on several computational grids are given and compared with other popular methods.

Hendrickson, B.; Leland, R.

1993-01-01

319

Universities Earth System Scientists Program  

Science.gov (United States)

This document constitutes the final technical report for the National Aeronautics and Space Administration (NASA) Grant NAGW-3172. This grant was instituted to provide for the conduct of research under the Universities Space Research Association's (USRA's) Universities Earth System Scientist Program (UESSP) for the Office of Mission to Planet Earth (OMTPE) at NASA Headquarters. USRA was tasked with the following requirements in support of the Universities Earth System Scientists Programs: (1) Bring to OMTPE fundamental scientific and technical expertise not currently resident at NASA Headquarters covering the broad spectrum of Earth science disciplines; (2) Conduct basic research in order to help establish the state of the science and technological readiness, related to NASA issues and requirements, for the following, near-term, scientific uncertainties, and data/information needs in the areas of global climate change, clouds and radiative balance, sources and sinks of greenhouse gases and the processes that control them, solid earth, oceans, polar ice sheets, land-surface hydrology, ecological dynamics, biological diversity, and sustainable development; (3) Evaluate the scientific state-of-the-field in key selected areas and to assist in the definition of new research thrusts for missions, including those that would incorporate the long-term strategy of the U.S. Global Change Research Program (USGCRP). This will, in part, be accomplished by study and evaluation of the basic science needs of the community as they are used to drive the development and maintenance of a global-scale observing system, the focused research studies, and the implementation of an integrated program of modeling, prediction, and assessment; and (4) Produce specific recommendations and alternative strategies for OMTPE that can serve as a basis for interagency and national and international policy on issues related to Earth sciences.

Estes, John E.

1995-01-01

320

Martian Atmospheric Pressure Static Charge Elimination Tool  

Science.gov (United States)

A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

Johansen, Michael R.

2014-01-01

 
 
 
 
321

High-pressure neutron diffraction  

Energy Technology Data Exchange (ETDEWEB)

This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

Xu, Hongwu [Los Alamos National Laboratory

2011-01-10

322

Thermal structure and energy balance of Uranus  

Science.gov (United States)

The present study determines the basic properties of the atmospheric temperature field of Uranus through a combination of earth-based and Voyager measurements. Stellar occultation observations indicate both spatial and temporal variability at microbar pressure levels. The tropospheric and stratospheric vertical structure are established via Voyager radio occultation and infrared measurements as well as earth-based full-disk infrared observations. It is found that the measured lapse rate at pressures greater than about 600 microbar exceeds that for fully equilibrated ortho and para hydrogen. The latitude dependence of the upper tropospheric temperatures is determined from Voyager infrared measurements; remarkably little contrast is found. The weak horizontal structure is consistent with tropospheric zonal winds which decay with height and are directed prograde at midlatitudes but retrograde at low latitudes.

Conrath, B. J.; Pearl, J. C.; Appleby, J. F.; Lindal, G. F.; Orton, G. S.; Bezard, B.

1991-01-01

323

Investigating of relationship between balance parameters and balance lost of elite gymnastics on balance beam  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to investigate the relationship between balance lost on balance beam during the series performed by women gymnasts at International Bosphorus Gymnastics Tournament with anthropometric characteristics and static-dynamic balance test scores.19 female gymnasts (ages 14,53±2,20, training years9,0±3 participated in this research voluntarily. Before the competition, the static and dynamic balance score and anthropometrics values were taken by experienced researchers. In order to analyze balance loss on balance beam routines were evaluated by four international judges. The relationship between balance lost on balance beam and balance abilities were tested by “Pearson Correlation Analysis”.As a result although there were a negative relationship between dynamic balance parameters with age, training experience, some anthropometric features (p0,05. There were high negative relationship between final score and balance lost in balance beam series (p0,05.Artistic gymnastics training contribute positively to the improvement of balance skills, which may have enabled the gymnasts to preserve their balances perfectly, even under difficult circumstances. It can be summarized that the ability of the gymnasts in preserving their balances in similar degree, both during competition and during the tests given under laboratory conditions, can be an outcome of their improved balance skills acquired through exercise.

Salih P?nar

2012-10-01

324

Free oscillation of the Earth  

Directory of Open Access Journals (Sweden)

Full Text Available   This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillations of stars was studied by Cowling and others. They classified the oscillation modes of the stars into acoustic and gravity modes on the basis of their driving forces. These are pressure and buoyancy forces respectively. The earliest measurements for the period of the free oscillations of the Earth was made by Benyove from a study of Kamchathca earthquake. Since then, the Geophysicists have been trying to provide a theoretical basis for these measurements. Recently, the theory concerning oscillations of celestial fluids is extended by Sobouti to include the possible oscillations of the Earthlike bodies. Using the same technique, we study the free oscillations of a spherically symmetric, non-rotating and elastic model for the Earth.   We used the actual data of the Earths interior structure in our numerical calculations. Numerical results show that there exist three distinct oscillation modes namely acoustic, gravity and toroidal modes. These modes are driven by pressure, buoyancy and shear forces respectively. The shear force is due to the elastic properties of the solid part of the Earth. Our numerical results are consistent with the seismic data recorded from earthquake measurements.

Y. Abedini

2000-06-01

325

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.)

326

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.)

327

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.)

328

Balance Disorders (For Parents)  

Science.gov (United States)

... need one or more of the following: a hearing aid (that fits inside or behind the ear and make sounds louder) an FM system or "auditory trainer" (specialized devices ... kids adapt their hearing and balance) When to See a Doctor It's ...

329

National energy balance 1991  

International Nuclear Information System (INIS)

The National Energy Balance of 1991 shows the data of production, consumption and the external dependence of energy in the different energy groups. The supply and demand of energy by source and the resources and energy reserves are also presented. (C.G.C.)

330

National energy balance 1990  

International Nuclear Information System (INIS)

The national energy balance of 1990 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.)

331

Regulation of Energy Balance.  

Science.gov (United States)

Explains relationships between energy intake and expenditure focusing on the cellular, chemical and neural mechanisms involved in regulation of energy balance. Information is referenced specifically to conditions of obesity. (Physicians may earn continuing education credit by completing an appended test). (ML)

Bray, George A.

1985-01-01

332

Mobility Balance Sheet 2010  

International Nuclear Information System (INIS)

The Mobility Balance Sheet 2010 provides an overview of the developments with regard to mobility in the Netherlands in the last decade. The overview also comprises the economic crisis and the consequences for traffic and transport in the Netherlands. Regarding the start of a new government also a medium-term outline is given for the next five years.

333

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.)

334

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

335

Lives in the Balance.  

Science.gov (United States)

Changes in the workplace that would provide flexibility for working parents are slowly developing and receiving government, business, and societal attention. A sidebar, "Mother, Professional, Volunteer: One Woman's Balancing Act," presents an account of how one woman rearranged her professional life to enable her to do full-time parenting. (SM)

Our Children, 1997

1997-01-01

336

Social Balance Experiment  

Science.gov (United States)

This is the entry page for participation in the Social Balance Experiment. In this experiment, participants are asked to imagine that they are in a situation in which they have one of five feelings (love, like, neutral, dislike or hate) toward another person named Bill.

337

Cadmium (Materials Balance).  

Science.gov (United States)

The U.S. Bureau of Mines report presents a concise review on sources, processes, supply, and historical use patterns of domestic cadmium. It also covers a preliminary estimated cadmium material balance for the year 1989. The report also discusses U.S. cad...

T. O. Llewellyn

1992-01-01

338

Earth Sciences: Instrumentation and Facilities  

Science.gov (United States)

... of Earth Sciences (EAR/IF) supports meritorious requests within and across Earth science disciplines ... for Earth science research instrumentation; Development of Cyberinfrastructure for the Earth ...

339

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 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.

340

Effect of rare earth on lattice size and equilibrium hydrogen pressure for AB{sub 5}-type MmNi{sub 3.55}Co{sub 0.75}Al{sub 0.30}Mn{sub 0.40}  

Energy Technology Data Exchange (ETDEWEB)

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 MmNi{sub 3.55}Co{sub 0.75}Al{sub 0.30}Mn{sub 0.40} using X-ray diffraction (XRD) and pressure-composition (P-C) isotherms measurements. We successfully prepared the alloys, where Mm was composed of M{sub x}La{sub 0.81-x}Nd{sub 0.14}Pr{sub 0.05} (M{sub x} = Ce{sub 0.47}, Y{sub 0.40}, Gd{sub 0.25}, Tm{sub 0.20}, Lu{sub 0.16}). 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.

Endo, Daisuke [GS-YUASA Corporation, Nishinosho, Kisshoin, Minami-ku, Kyoto 601-8520 (Japan)], E-mail: daisuke.endo@jp.gs-yuasa.com; Sakaki, Kouji; Akiba, Etsuo [National Institute of Advanced Industrial Science and Technology (AIST), AIST Central-5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan)

2008-07-14

 
 
 
 
341

Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs  

Science.gov (United States)

Crewmembers returning from long-duration space flight face significant challenges due to the microgravity-induced inappropriate adaptations in balance/ sensorimotor function. The Neuroscience Laboratory at JSC is developing a method based on stochastic resonance to enhance the brain s ability to detect signals from the balance organs of the inner ear and use them for rapid improvement in balance skill, especially when combined with balance training exercises. This method involves a stimulus delivery system that is wearable/portable providing imperceptible electrical stimulation to the balance organs of the human body. Stochastic resonance (SR) is a phenomenon whereby the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. This phenomenon of SR is based on the concept of maximizing the flow of information through a system by a non-zero level of noise. Application of imperceptible SR noise coupled with sensory input in humans has been shown to improve motor, cardiovascular, visual, hearing, and balance functions. SR increases contrast sensitivity and luminance detection; lowers the absolute threshold for tone detection in normal hearing individuals; improves homeostatic function in the human blood pressure regulatory system; improves noise-enhanced muscle spindle function; and improves detection of weak tactile stimuli using mechanical or electrical stimulation. SR noise has been shown to improve postural control when applied as mechanical noise to the soles of the feet, or when applied as electrical noise at the knee and to the back muscles.

Bloomberg, Jacob; Reschke, Millard; Mulavara, Ajitkumar; Wood, Scott; Serrador, Jorge; Fiedler, Matthew; Kofman, Igor; Peters, Brian T.; Cohen, Helen

2012-01-01

342

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

343

Momentum balances on the North Carolina inner shelf  

Science.gov (United States)

Four months of moored current, pressure, temperature, conductivity, wave, and wind observations on the North Carolina shelf indicate three dynamically distinct regions: the surf zone, the inner shelf between the surf zone and the 13-m isobath, and the midshelf. In the surf zone the along-shelf momentum balance is between the cross-shelf gradient of the wave radiation stress and the bottom stress. The linear drag coefficient in the surf zone is about 10 times larger than seaward of the surf zone. On the inner shelf the along-shelf momentum balance is also frictional; the along-shelf wind stress and pressure gradient are balanced by bottom stress. In the cross-shelf momentum balance the pressure gradient is the superposition of roughly equal contributions from the Coriolis force (geostrophy) and wave setdown from shoaling, unbroken surface gravity waves. At midshelf the along-shelf momentum balance is less frictional and hence flow accelerations are important. The cross-shelf momentum balance is predominantly geostrophic because the greater depth and smaller bottom slope at midshelf reduce the importance of wave setdown. The cross-shelf density gradient is in thermal wind balance with the vertical shear in the along-shelf flow in depths as shallow as 10 m. The dominant along-shelf momentum balances provide a simple estimate of the depth-averaged, along-shelf current in terms of the measured forcing (i.e., wind stress, wave radiation stress divergence, and along-shelf pressure gradient) that reproduces accurately the observed cross-shelf variation of the depth-averaged, along-shelf current between the surf zone and midshelf.

Lentz, Steve; Guza, R. T.; Elgar, Steve; Feddersen, Falk; Herbers, T. H. C.

1999-08-01

344

A hydrogen-rich early Earth atmosphere.  

Science.gov (United States)

We show that the escape of hydrogen from early Earth's atmosphere likely occurred at rates slower by two orders of magnitude than previously thought. The balance between slow hydrogen escape and volcanic outgassing could have maintained a hydrogen mixing ratio of more than 30%. The production of prebiotic organic compounds in such an atmosphere would have been more efficient than either exogenous delivery or synthesis in hydrothermal systems. The organic soup in the oceans and ponds on early Earth would have been a more favorable place for the origin of life than previously thought. PMID:15817816

Tian, Feng; Toon, Owen B; Pavlov, Alexander A; De Sterck, H

2005-05-13

345

The Influence of the Atmospheric Transmission for the Solar Radiation and Earth’s Surface Radiation on the Earth’s Climate  

Directory of Open Access Journals (Sweden)

Full Text Available The physical and mathematical model of the planetary heat balance is developed to establish the influence of the atmospheric transmission for the solar radiation in the shortwave spectrum range and for the surface IR radiation in the longwave spectrum range on the Earth’s climate. It is shown the possibility of the decreas- ing of the atmospheric and surface temperatures with the decreasing of the atmospheric transmission for IR spectrum range, and this decreasing can’t be equilibrated with the change of the atmospheric transmission for the incoming solar radiation.

Alexander I. Bogoyavlenskii

2010-10-01

346

Analysis of pressurizer pressure control system using MAAP5 code  

International Nuclear Information System (INIS)

Full text of publication follows. MAAP4 code is a severe accident analysis code, widely used in nuclear industry. Pressurizer response plays an important role in transient and accident analysis. However, only simplified pressurizer pressure control system model is included in MAAP4 code. The purpose of the paper is to modify the pressurizer pressure control system model in MAAP4 without compiling the code, promoting the simulation capability and accuracy of the MAAP4 code. The typical proportional and integral (PI) controller model is successfully coupled with current code without compiling. Typical control system analysis is analyzed using MAAP4. Furthermore, the characteristic of PI controller is demonstrated, which reduces the steady state error to zero. With the revised pressurizer pressure control system, the transient responses are more realistic. It can be coupled with balance of plant model for whole plant simulation in MAAP5 code in the near future. (authors)

347

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

348

Ballet Balance Strategies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Animating physically realistic human characters is challenging, since human observers are highly tuned to recognize human cues such as emotion and gender from motion patterns. The main contribution of this paper is a new model firmly based on biomechanics, which is used to animate balance and basic movements of a ballet dancers. It is supported by computer simulated experiments and it is in good agreement with biomechanical measurements of real-life dancers. Our results questions the previous...

Pedersen, Camilla; Erleben, Kenny; Sporring, Jon

2006-01-01

349

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.)

350

Asiantuntijaorganisaation Balanced Scorecard  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this thesis is to develop the balanced scorecard for the company whose business is based on knowledge of the staff and application of continuous information. The company is growing impartial expert organization that offers financial management expertise to businesses and communities. The objective of the enterprise is to design the metrics to take advantage of the strategic objectives, as well as committing the staff to company’s values. As a result of the metrics, the aim of the...

Poutiainen, Kari

2011-01-01

351

Modeling your Water Balance  

Science.gov (United States)

Students create a physical model illustrating soil water balance using drinking glasses to represent the soil column, and explain how the model can be used to interpret data and form predictions. Using data from the GLOBE Data Server, they calculate the potential evapotranspiration, average monthly temperatures and precipitation for their model. This is a learning activity associated with the GLOBE hydrology investigations and is supported by the Hydrology chapter of the GLOBE Teacher's Guide.

352

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

353

Pressure Dome for High-Pressure Electrolyzer  

Science.gov (United States)

A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom segment and is trapped by the flange on the top dome segment when these components are bolted together with high-strength bolts. The pressure dome has several unique features. It is made (to ASME Pressure Vessel guidelines) in a high-strength aluminum alloy with the strength of stainless steel and the weight benefits of aluminum. The flange of the upper dome portion contains specially machined flats for mounting the dome, and other flats dedicated to the special feedthroughs for electrical connections. A pressure dome can be increased in length to house larger stacks (more cells) of the same diameter with the simple addition of a cylindrical segment. To aid in dome assembly, two stainless steel rings are employed. One is used beneath the heads of the high-strength bolts in lieu of individual hardened washers, and another is used instead of individual nuts. Like electrolyzers could be operated at low or high pressures simply by operating the electrolyzer outside or inside a pressurized dome.

Norman, Timothy; Schmitt, Edwin

2012-01-01

354

groundwater water balance classification method  

...i)]. Water Balance classification The method for water balance classification is...is no 100 % fail safe method to calculate recharge rates. The...this was to apply a method recently adopted by the Republic...

355

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... wrong with me. I couldn't keep my balance and I was seeing double. Man: I woke ... getting senile because the vertigos -- it upset my balance completely. Narrator: These people are discussing a problem ...

356

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... activities of daily living. Narrator: Our body's balance system is what allows us to move, stand erect, ... maintain balance with the help of our vestibular system, which is located in the inner ear. A. ...

357

Statistics of pressure and of pressure-velocity correlations in isotropic turbulence  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Some pressure and pressure-velocity correlation in a direct numerical simulations of a three-dimensional turbulent flow at moderate Reynolds numbers have been analyzed. We have identified a set of pressure-velocity correlations which posseses a good scaling behaviour. Such a class of pressure-velocity correlations are determined by looking at the energy-balance across any sub-volume of the flow. According to our analysis, pressure scaling is determined by the dimensional ass...

Biferale, L.; Gualtieri, P.; Toschi, F.

2000-01-01

358

Balancing mechanism status: August 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for August 2009. (J.S.)

359

Balancing mechanism status: July 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for July 2009. (J.S.)

360

Balancing mechanism status: January 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for January 2009. (J.S.)

 
 
 
 
361

Balancing mechanism status: December 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for December 2009. (J.S.)

362

Balancing mechanism status: February 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for February 2009. (J.S.)

363

Balancing mechanism status: May 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for May 2009. (J.S.)

364

Balancing mechanism status: June 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for June 2009. (J.S.)

365

Balancing mechanism status: April 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for April 2009. (J.S.)

366

Balancing mechanism status: November 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for November 2009. (J.S.)

367

Balancing mechanism status: October 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for October 2009. (J.S.)

368

Balancing mechanism status: September 2009  

International Nuclear Information System (INIS)

RTE ensures the real-time balance between production and consumption and deals with congestion on the French electricity system. The Balancing Mechanism assists in the accomplishment of this task. As in many countries, and after extensive dialogue with representatives from the market's various players, RTE proposes a Balancing Mechanism in the form of a permanent and transparent system of calls for tender. The system is open to everyone and provides a real-time reserve of power that can be used for balancing either upward or downward. RTE takes advantage of these offers according to economic precedence, taking into account the system's operating conditions. It pays for them at the offer price. There are two types of offer: - Upward offer: increase in production, decrease in consumption, imports, - Downward offer: decrease in production, increase in consumption, exports. For a Balancing Entity, an offer systematically consists of: a balancing direction (upward/downward), a time period, a price that may vary according to six time slots. RTE publishes each month a Balancing Mechanism Report. which includes the following information: - energy volumes activated to ensure the balance of the system and to resolve congestion; - minimum and maximum prices of offers activated to balance the system; - daily trends calculated according to the predominant value of the overall upward or downward trend; - balancing shares by technology (nuclear, thermal, hydraulic); - characteristics of the five most activated balancing entities; - balances/imbalances accounts and production/consumption overcharge; - congestion curbing costs on the French electricity system; - energy volumes activated to ensure the balance of the system according to contracts between RTE and other Balance Responsible entities (UK, Belgium, Italy, Germany, Switzerland); - reliability of the provisional data supplied by RTE about the balancing trend; - availability of RTE's information services (planning, balancing mechanism, block exchange notification, market indicators). This report presents the above information for September 2009. (J.S.)

369

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

370

Pressure Sores  

Science.gov (United States)

... may form. Pressure sores are also called bedsores, pressure ulcers and decubitus ulcers. Symptoms What are the symptoms of a ... put in a vein) or orally (by mouth). Prevention How can pressure sores be prevented? The most ...

371

Pressure ulcer  

Science.gov (United States)

Bedsore; Decubitus ulcer ... If you have a pressure ulcer: Relieve the pressure on that area. Use pillows, special foam cushions, and sheepskin to reduce the pressure. Treat the sore as directed by your ...

372

The MHD structure of the plasmasheet boundary. I - Tangential momentum balance and consistency with slow mode shocks  

Science.gov (United States)

The MHD structure of the plasmasheet boundary in the near tail is investigated on the basis of data from the AMPTE/IRM spacecraft. The relationship between the change in the tangential velocity predicted by the Rankine-Hugoniot relations for a discontinuity with a normal magnetic field and the measured change in the tangential velocity for about 80 crossings is presented. The measured change is almost always much less than the predicted value. It is suggested that either there is not usually a normal component of the magnetic field across the boundary (combined with previous work on pressure balance, this implies that the boundary is a tangential discontinuity), or the boundary is not usually well-modeled as a planar, time-stationary MHD discontinuity. It is proposed that the magnetic connection to the earth inhibits the formation of slow mode shocks.

Cattell, C. A.; Carlson, C. W.; Baumjohann, W.; Luehr, H.

1992-01-01

373

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

374

Investigating of relationship between balance parameters and balance lost of elite gymnastics on balance beam  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to investigate the relationship between balance lost on balance beam during the series performed by women gymnasts at International Bosphorus Gymnastics Tournament with anthropometric characteristics and static-dynamic balance test scores.19 female gymnasts (ages 14,53±2,20, training years9,0±3) participated in this research voluntarily. Before the competition, the static and dynamic balance score and anthropometrics values were taken by experienced researchers. In...

Salih P?nar; Ufuk Alpkaya; Manolya Ak?n; Ay?e Oya Erkut At?lgan

2012-01-01

375

Entropy of balance - some recent results  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Entropy when applied to biological signals is expected to reflect the state of the biological system. However the physiological interpretation of the entropy is not always straightforward. When should high entropy be interpreted as a healthy sign, and when as marker of deteriorating health? We address this question for the particular case of human standing balance and the Center of Pressure data. Methods We have measured and analyzed balance data of 136 participants (young, n = 45; elderly, n = 91 comprising in all 1085 trials, and calculated the Sample Entropy (SampEn for medio-lateral (M/L and anterior-posterior (A/P Center of Pressure (COP together with the Hurst self-similariy (ss exponent ? using Detrended Fluctuation Analysis (DFA. The COP was measured with a force plate in eight 30 seconds trials with eyes closed, eyes open, foam, self-perturbation and nudge conditions. Results 1 There is a significant difference in SampEn for the A/P-direction between the elderly and the younger groups Old > young. 2 For the elderly we have in general A/P > M/L. 3 For the younger group there was no significant A/P-M/L difference with the exception for the nudge trials where we had the reverse situation, A/P Eyes Open. 5 In case of the Hurst ss-exponent we have for the elderly, M/L > A/P. Conclusions These results seem to be require some modifications of the more or less established attention-constraint interpretation of entropy. This holds that higher entropy correlates with a more automatic and a less constrained mode of balance control, and that a higher entropy reflects, in this sense, a more efficient balancing.

Laxåback Gerd

2010-07-01

376

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

377

Tai Chi and balance control.  

Science.gov (United States)

Balance function begins to decline from middle age on, and poor balance function increases the risk of fall and injury. Suitable exercise training may improve balance function and prevent accidental falls. The coordination of visual, proprioceptive, vestibular and musculoskeletal system is important to maintain balance. Balance function can be evaluated by functional balance testing and sensory organization testing. Tai Chi Chuan (TC) is a popular conditioning exercise in the Chinese community, and recent studies substantiate that TC is effective in balance function enhancement and falls prevention. In studies utilizing functional balance testing, TC may increase the duration of one-leg standing and the distance of functional reach. In studies utilizing sensory organization testing, TC improves static and dynamic balance, especially in more challenging sensory perturbed condition. Therefore, TC may be prescribed as an alternative exercise program for elderly subjects or balance-impaired patients. Participants can choose to perform a complete set of TC or selected movements according to their needs. In conclusion, TC may improve balance function and is appropriate for implementation in the community. PMID:18487891

Wong, Alice M K; Lan, Ching

2008-01-01

378

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