WorldWideScience
1

Modeling Earth's Energy Balance  

Science.gov (United States)

In this lab students learn how to create hierarchies of models of increasing complexity to understand some physical process - in this case, the absorption of solar energy by the Earth and its radiation of that energy back to space. Whenever one sets out to understand a complex phenomenon, it is best to start with the simplest possible model that explains most of the behavior of that phenomenon and to build upward in complexity gradually. In this exercise students learn how to do this by modeling the energy balance at Earth's surface. The exercise begins by assuming that the Earth is a perfect black body lacking an atmosphere, then moves on to incorporate the fact that Earth reflects much of the solar radiation incident upon it, and later incorporates the fact that Earth has an atmosphere. Each time something is added to the model students evaluate the output and compare it to actual Earth surface conditions to see how well each refinement captures the reality of the physics of heat absorption, exchange, and emission.

Kirsten Menking

2

Dual shell pressure balanced vessel  

Science.gov (United States)

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

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

3

Pressure balance at the magnetopause: Experimental studies  

CERN Document Server

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

Suvorova, A V

2011-01-01

4

Gallery Walk Questions on Earth's Radiation Balance  

Science.gov (United States)

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

5

Towards a Balanced Power Budget for Earth  

Science.gov (United States)

Probable mechanisms that produce or absorb power for Earth and the amount of power they individually produce or absorb are enumerated. Power-producers include radiogenic heat from the core, mantle, and crust; latent heat of crystallization from the growing inner core; gravitational heat from the thermal contraction of Earth due to its cooling; and gravitational heat from the growing crust. Generation of mantle plumes is also taken to be a power producer. The lifetime of the inner core must be consistent with the power produced in the core. I use the preferred model of Nimmo et al. (2004) in which the power produced by the core is augmented by 2.1 terawatts (TW) of potassium-produced radiogenic energy, giving a total power of 7.1~TW flowing from the core to the mantle. The chief difficulty in making the power balance is to find the value of the mantle's radiogenic power. I do this by enumerating the nonradiogenic power of the mantle excluding the lithosphere, but including the power from the core. This enumeration includes power from mantle convection, from mantle plumes, and nonradiogenic power arriving from the core, the sum of which crosses the basal plane boundary of the lithosphere. Since this sum must equal Earth's total heat loss (44.3 TW) less the mantle's radiogenic power, I find the mantle's radiogenic power to be 23.5 ± 1.5~TW. This is lower than mantle radiogenic power estimates from Turcotte and Schubert (2002) and greater than from Stacey (1992). The power budget for the lithosphere and the crust is taken from Turcotte and Schubert (2002), except that it is modified to include the power loss from tidal dissipation (4 TW), which Verhoogen (1980) recommends be taken into account. Expenditures in the lithosphere are tidal dissipation, continental radiogenic heating, basal heating of the lithosphere and subduction of the lithosphere. Within the error limits set by the various mechanisms, the power income of Earth is found to equal its power expenditure and also equal its measured power loss (44.3 TW).

Anderson, O. L.

2005-05-01

6

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

OpenAIRE

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.

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

2010-01-01

7

High pressure polymorphism of rare earth sulfideiodides  

International Nuclear Information System (INIS)

High pressure transformations of rare earth sulfideiodides are reported. Compounds with the GdSI-type structure (GdSI to DySI) transform to the SmSI-type within the pressure range up to 40 kb. For GdSI itself an ?-CeSI-type arrangement can be achieved additionally in the higher pressure range. All compounds crystallizing in the SmSI-type at ambient pressures transform to the ?-CeSI-type under such conditions. We explain these structures briefly in terms of a topological description, and we offer a structure model for GdSI. Possible reaction mechanism are discussed in comparison with similar transformations in LnOCl and LnSF compounds. (author)

8

Novel reduced pressure-balance syringe for chromatographic analysis.  

Science.gov (United States)

When withdrawing a fluid sample (for additional chromatographic analyses) from an apparatus operated at a reduced pressure, a typical syringe proves to be ineffective (even if it is equipped with a gas tight plunger). It simply does not create enough pressure differential to remove a fluid sample from a reduced pressure environment. We encountered such a situation as part of efforts to extend the operation of the advanced distillation curve protocol to reduced pressures. The problem was solved by the development of a pressure balance syringe that allows reliable and precise sampling from an apparatus operating at sub-ambient pressures. This new device uses an external vacuum source to evacuate a syringe barrel, allowing a user to withdraw fluid samples from environments with pressures as low as 0.5kPa. To demonstrate the operation of the newly developed device, distillate analyses were performed on two fluids at low pressure: a predefined validation mixture, and a commercial soy based biodiesel fuel. The pressure balance syringe was used successfully for sampling in both cases. The use of the pressure balance syringe is not limited to reduced pressure distillations; indeed it can be used for a variety of applications in which chemical/compositional analyses are desired on a fluid contained in a reduced pressure environment. PMID:20961548

Windom, Bret C; Bruno, Thomas J

2010-11-19

9

Pressure balance across the magnetopause: Global MHD results  

Science.gov (United States)

The equilibrium magnetopause location on the dayside is determined by the balance of pressure forces. In this paper we use a physics-based global magnetohydrodynamic (MHD) to examine contributions of different terms to this balance. We calculate the total pressure, as well as thermal and magnetic pressures just inside and just outside the magnetopause. Our results show that (1) the total pressure just outside the magnetopause is enhanced with the increasing of BZ in both northward and southward interplanetary magnetic field (IMF). For southward IMF the thermal pressure is dominant in the total pressure while the magnetic pressure is dominant for northward IMF when BZ is not small (BZ > 5 nT). For southward IMF larger solar wind dynamic pressure further enhances thermal pressure near the magnetopause while for northward IMF the dynamic pressure is more effectively converted to the magnetic pressure; (2) the thermal pressure just outside the magnetopause is significantly enhanced with the increasing southward IMF as compared to the northward IMF case. However, this enhanced thermal pressure is not the only reason for the well-known earthward displacement of the magnetopause under southward IMF conditions. The dayside magnetic reconnection for southward IMF dramatically decreases magnetic pressure just inside the magnetopause. The combination of these two factors explains the Earthward motion of the magnetopause for southward IMF.

Lu, J. Y.; Wang, M.; Kabin, K.; Zhao, J. S.; Liu, Z.-Q.; Zhao, M. X.; Li, G.

2015-02-01

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, Michael W. (Gilbert, AR); Cole, Jack H. (Fayetteville, AR)

1982-01-01

11

Mechanisms of sodium balance in hypertension: role of pressure natriuresis.  

Science.gov (United States)

This paper summarizes the role of the renal pressure natriuresis and diuresis mechanisms in maintaining sodium and water balance in hypertension. In all forms of chronic hypertension studied to date, the renal pressure natriuresis and diuresis mechanisms are abnormal, since increased arterial pressure is required to maintain normal excretion of sodium and water, and therefore fluid balance. When renal perfusion pressure is prevented from increasing in various forms of experimental hypertension, caused by infusion of mineralocorticoids, angiotensin II, vasopressin, or norepinephrine and adrenocorticotrophic hormone (ACTH), sodium and water retention continues until ascites, pulmonary oedema and circulatory collapse occur within a few days. Thus, chronic hypertension appears to be an essential homeostatic response that permits sodium and water balance to be maintained despite various abnormalities which tend to decrease renal excretory capability. The intrarenal mechanisms by which increased renal perfusion pressure maintains sodium and water balance in hypertension have not been fully elucidated, but appear to involve small changes in glomerular filtration rate (GFR) and reductions in fractional sodium reabsorption, due either to the direct hydraulic effects of pressure or to various indirect effects, such as changes in angiotensin II formation. PMID:3021942

Hall, J E; Granger, J P; Hester, R L; Montani, J P

1986-10-01

12

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

OpenAIRE

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...

Bret, A.

2011-01-01

13

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

CERN Document Server

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

Aboumoussa, Walid

2014-01-01

14

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

15

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

16

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

International Nuclear Information System (INIS)

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

17

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

OpenAIRE

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 co...

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

2013-01-01

18

Interstellar pickup protons at pressure-balanced structures  

International Nuclear Information System (INIS)

A recent attempt to measure the presence of interstellar pickup protons in the distant solar wind through their effects on the variations within pressure-balanced structures found no evidence of these particles (Burlaga et al., 1990). That study concluded that the pickup protons, expected to be correlated with the solar wind density through the charge exchange ionization process, had become smeared in the radial direction. The resulting constant pressure rendered these particles undetectable by the analysis used. This paper presents an improved analysis which takes into account the cooling of these particles in the expanding solar wind. This improvement does not change the conclusions of the previous work. The possibility that quasi-linear perpendicular diffusion is responsible for the inferred smearing across field lines is then investigated. It is shown that this mechanism can easily produce the required transport over the radial dimension of such a structure

19

Crystallographic phases in heavy rare earth metals under megabar pressures  

Science.gov (United States)

Experiments aimed at understanding the crystallographic phases of heavy rare earth metals were carried out in a diamond anvil cell at the Advanced Photon Source, Argonne National Laboratory. Heavy rare earth metals dysprosium (Dy), holmium (Ho), erbium (Er) and thulium (Tm) were compressed to multi-megabar pressures. The rare earth crystal sequence hcp?Sm-type?dhcp?distorted-fcc (dfcc) is observed in all four elements. Upon further compression, a structural transformation to a monoclinic C2/m phase has been observed. We summarize the results from these experiments and present Rietveld structural refinements on high pressure phases for the specific case of dysprosium.

Samudrala, G. K.; Vohra, Y. K.

2012-07-01

20

Dual shell pressure balanced reactor vessel. Final project report  

Energy Technology Data Exchange (ETDEWEB)

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&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).

Robertus, R.J.; Fassbender, A.G.

1994-10-01

21

Stability of hydrocarbons at deep Earth pressures and temperatures  

OpenAIRE

Determining the thermochemical properties of hydrocarbons (HCs) at high pressure and temperature is a key step toward understanding carbon reservoirs and fluxes in the deep Earth. The stability of carbon-hydrogen systems at depths greater than a few thousand meters is poorly understood and the extent of abiogenic HCs in the Earth mantle remains controversial. We report ab initio molecular dynamics simulations and free energy calculations aimed at investigating the formation of higher HCs from...

Spanu, Leonardo; Donadio, Davide; Hohl, Detlef; Schwegler, Eric; Galli, Giulia

2011-01-01

22

Changes in Earth's radiation balance between 1985 and 2012  

Science.gov (United States)

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

Orwig, Jessica

2014-11-01

23

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

24

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

25

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

26

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

27

Ultra-High-Pressure Experimentalist Who Studies the Deep Earth  

Science.gov (United States)

This article profiles the work of Elise Knittle, whose research specialty is mineral physics. The essay gives an overview of the core, mantle, and crust of the Earth, including what we know about their physical properties. It explains the work of the author, studying the chemical interactions between the metals that make up the Earth's core and the silicate minerals that compose the mantle. The obstacles and challenges she faces in re-creating the intense heat and pressure of the deep Earth using incredibly small samples are explained. Most of the recent work of the author is on subduction zones, trying to determine what happens to the slabs of oceanic crust that descend into the mantle.

28

Precariousness and hazard of lateral earth pressure theory.  

Czech Academy of Sciences Publication Activity Database

Reston : American Society of Civil Engineers, 2014 - (Beer, M.; Au, S.; Hall, J.), s. 2765-2779 ISBN 978-0-7844-1360-9. [International Conference on vulnerability and risk analysis and management /2./. Liverpool (GB), 13.07.2014-16.07.2014] Institutional support: RVO:68378297 Keywords : earth pressure * EUROCODE 7-1 * soils Subject RIV: JM - Building Engineering http://ascelibrary.org/doi/abs/10.1061/9780784413609.279

Koudelka, Petr

29

Phase transitions in rare earth tellurides under pressure  

International Nuclear Information System (INIS)

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

30

Phase transitions in rare earth tellurides under pressure  

Science.gov (United States)

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

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

2014-07-01

31

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

32

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

International Nuclear Information System (INIS)

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

33

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

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

34

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

35

Mathematical model of Lame Problem for Simplified Elastic Theory applied to Controlled-Clearance Pressure Balances  

CERN Document Server

This paper is based on the original work of the master degree thesis [1] and also represents a revision of the models and the correlations with the analytical solutions given by other authors in the previous publications from 2003 to 2007. All the publications from 2003 to 2007 about simplified analytical methods applied to controlled-clearance pressure balances are not original re-elaborations (with some errors) of the thesis[1]. The analysis described in this paper starts with the mathematical model of thick-walled cylinder based on the solution of the Lame Equations applied to Mechanical theory of elastic equilibrium [5] for the formulation of the so called Simplified Elastic Theory that represents an analytical approach used in the study of the pressure balances. This analysis is well known as Lame problem. The solution of the Lame problem is used to determine the pressure distortion coefficient of controlled-clearance pressure balances. The analysis in this paper includes the case of pressure balances wi...

Silvano, Saragosa

2010-01-01

36

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

CERN Document Server

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

Rajeev, P; Sivakugan, N

2015-01-01

37

Experimental and analytical study on earth pressure of an embedded building model during earthquakes  

International Nuclear Information System (INIS)

The objective of this paper is to describe the characteristics of earth pressure during earthquakes for an embedded building model, revealed form earthquake observation and simulation analyses. This paper reports on a study in which the earth pressure records during earthquakes were investigated and were simulated by two and three-dimensional FEM

38

Pressure balance and pressure distribution along the dayside ionopause of Venus  

International Nuclear Information System (INIS)

The pressure distribution within the magnetic barrier just outside the ionopause of Venus is shown to be similar to expected solar wind pressure variation. The important role of solar wind heating of the subsolar ionosphere and the significant influence of transport processes within the ionosphere at large solar zenith angle on the shape of the venusian ionosphere are examined. It is considered that the model of the subionopause pressure distribution with height and with the solar zenith angle seems to represent reasonably the observed behaviour of ionopause crossings at different solar zenith angle and allows one to obtain an 'instant' profile of the ionopause for given solar wind pressure. (UK)

39

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

International Nuclear Information System (INIS)

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

40

The energy balance of the material breaking under the action of the high pressure water jet  

OpenAIRE

For a correct determination of the cutting process parameters by high pressure water jet, it is necessary to study the breaking mechanism of the material under the action of the water jet. From the analysis of the material behavior under high pressure water jet, moving at supersonic speed, it appears like a micro-erosive process. We study the energy balance of the micro-erosive breaking of the material taking into account the nucleation energy of the micro-cracking, the internal energy variat...

Dumitru, G.; Zgura, G.

1994-01-01

41

HII regions in hydrostatic balance between gas pressure, radiation pressure and gravity  

Science.gov (United States)

We study the solutions of a modified version of the isothermal Lane-Emden equation, which incorporates the effect of the (owtwards directed) radiation pressure resulting from photoionizations. These solutions are relevant for HII regions around a cluster with over ?500 O stars, which can photoionize gas out to ??{10{cm}^{-3}/n_0}pc (where n_0 is the central gas density), where the effects of the self-gravity and the radiation pressure become important. We find that the solutions have a transition from a “gravity dominated” regime (in which the solutions converge at large radii to the non-singular, isothermal sphere solution) to a “radiation pressure dominated” regime (in which the density diverges at a finite radius) for central HII region densities above n_{crit}=100 cm^{-3}. We argue that the high central density, radiation pressure dominated solutions will not occur in most astrophysically relevant situations, because of the absence of a possible confining environment with a high enough pressure.

Raga, A. C.; Cantó, J.; Mellema, G.; Rodríguez-González, A.; Esquivel, A.

2015-04-01

42

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

Science.gov (United States)

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

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

2014-01-01

43

Prediction of Seismic Active Earth Pressure Using Curved Failure Surface with Localized Strain  

OpenAIRE

Problem statement: Correct evaluation of the earth pressure against retaining structure during earthquake is essential for the safe and economic design of geotechnical structures. Progressive deformation in the backfill and the assumed shape of failure wedge affect the calculated values of seismic earth pressures. However, no research until now is available that considers both of these two factors in an analysis. Approach: In this study, a new analytical methodology was proposed that took int...

Hemanta Hazarika

2009-01-01

44

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

45

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.

46

Dual Shell Pressure Balanced Reactor Vessel cooperative research and development agreement with Innotek, Inc., Final report  

Energy Technology Data Exchange (ETDEWEB)

The Department of Energy`s Office of Energy Research (OER) has 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. This document details a cooperative research and development agreement 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&D 100 award-winning technology, Sludge-to-oil Reactor System (STORS), originally developed through funding by OER.

Robertus, R.J.; Fassbender, A.G.; Deverman, G.S.

1995-04-01

47

Strutural phase transitions in rare earth sesquioxides under pressure  

Science.gov (United States)

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

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

2013-02-01

48

PRESSURE INDUCED TRANSITIONS IN SOME RARE-EARTH COMPOUNDS  

OpenAIRE

The pressure-volume dependence has been measured for CeTe, CeSb, LaSb and CeBi by x-ray diffraction on polycrystalline samples in a diamond anvil cell up to 25 GPa. All these compounds undergo first order polymorphic transitions under high pressure. From the comparison of the bulk moduli of the cerium and lanthanum compounds and from the variation of the Ce-X distance at the transition a continuous electronic transfer has been inferred in CeTe and CeBi in the f.c.c. phase followed by a back d...

Leger, J.; Oki, K.

1984-01-01

49

High pressure Earth storable rocket technology program: Basic program  

Science.gov (United States)

The HIPES Program was conducted for NASA-LeRC by TRW. The Basic Program consisted of system studies, design of testbed engine, fabrication and testing of engine. Studies of both pressure-fed and pump-fed systems were investigated for N2O4 and both MMH and N2H4 fuels with the result that N2H4 provides the maximum payload for all satellites over MMH. The higher pressure engine offers improved performance with smaller envelope and associated weight savings. Pump-fed systems offer maximum payload for large and medium weight satellites while pressure-fed systems offer maximum payload for small light weight satellites. The major benefits of HIPES are high performance within a confined length maximizing payload for lightsats which are length (volume) constrained. Three types of thrust chambers were evaluated -- Copper heatsink at 400, 500 and 600 psia chamber pressures for performance/thermal; water cooled to determine heat absorbed to predict rhenium engine operation; and rhenium to validate the concept. The HIPES engine demonstrated very high performance at 50 lbf thrust (epsilon = 150) and Pc = 500 psia with both fuels: Isp = 337 sec using N2O4-N2H4 and ISP = 327.5 sec using N2O4-MMH indicating combustion efficiencies greater than 98%. A powder metallurgy rhenium engine demonstrated operation with high performance at Pc = 500 psia which indicated the viability of the concept.

Chazen, M. L.; Sicher, D.; Huang, D.; Mueller, T.

1995-03-01

50

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

Science.gov (United States)

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

Berntsen, Jarle

51

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

International Nuclear Information System (INIS)

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

52

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

53

Advanced Pressure Coring System for Deep Earth Sampling (APRECOS)  

Science.gov (United States)

Nowadays the recovery of cores from boreholes is a standard operation. However, during that process the mechanical, physical, and chemical properties as well as living conditions for microorganisms are significantly altered. In-situ sampling is one approach to overcome the severe scientific limitations of conventional, depressurized core investigations by recovering, processing, and conducting experiments in the laboratory, while maintaining unchanged environmental parameters. The most successful equipment today is the suite of tools developed within the EU funded projects HYACE (Hydrate Autoclave Coring Equipment) and HYACINTH (Deployment of HYACE tools In New Tests on Hydrates) between 1997 and 2005. Within several DFG (German Research Foundation) projects the Technical University Berlin currently works on concepts to increase the present working pressure of 250 bar as well as to reduce logistical and financial expenses by merging redundant and analogous procedures and scaling down the considerable size of key components. It is also proposed to extend the range of applications for the wireline rotary pressure corer and the sub-sampling and transfer system to all types of soil conditions (soft to highly-consolidated). New modifications enable the tools to be used in other pressure related fields of research, such as unconventional gas exploration (coal-bed methane, tight gas, gas hydrate), CO2 sequestration, and microbiology of the deep biosphere. Expedient enhancement of an overall solution for pressure core retrieval, process and investigation will open the way for a complete on-site, all-purpose, in-situ equipment. The advanced assembly would allow for executing the whole operation sequences of coring, non-destructive measurement, sub-sampling and transfer into storage, measurement and transportation chambers, all in sterile, anaerobic conditions, and without depressurisation in quick succession. Extensive post-cruise handling and interim storage would be dispensable. The complete core processing and preparation of in-situ sample sections for worldwide shipping could be conducted within hours after retrieval.

Anders, E.; Rothfuss, M.; Müller, W. H.

2009-04-01

54

High pressure phase transitions in the rare earth metal erbium to 151 GPa  

Energy Technology Data Exchange (ETDEWEB)

High pressure x-ray diffraction studies have been performed on the heavy rare earth metal erbium (Er) in a diamond anvil cell at room temperature to a pressure of 151 GPa and Er has been compressed to 40% of its initial volume. The rare earth crystal structure sequence hcp{yields}Sm type{yields}dhcp{yields}distorted fcc (hcp: hexagonal close packed; fcc: face centered cubic; dhcp: double hcp) is observed in Er below 58 GPa. We have carried out Rietveld refinement of crystal structures in the pressure range between 58 GPa and 151 GPa. We have examined various crystal structures that have been proposed for the distorted fcc (dfcc) phase and the post-dfcc phase in rare earth metals. We find that the hexagonal hR 24 structure is the best fit between 58 and 118 GPa. Above 118 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.9%. We have also established a clear trend for the pressure at which a post-dfcc phase is formed in rare earth metals and show that there is a monotonic increase in this pressure with the filling of 4f shell.

Samudrala, Gopi K; Thomas, Sarah A; Montgomery, Jeffrey M; Vohra, Yogesh K [Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294 (United States)

2011-08-10

55

High pressure phase transitions in the rare earth metal erbium to 151 GPa  

Science.gov (United States)

High pressure x-ray diffraction studies have been performed on the heavy rare earth metal erbium (Er) in a diamond anvil cell at room temperature to a pressure of 151 GPa and Er has been compressed to 40% of its initial volume. The rare earth crystal structure sequence {hcp} \\to {Sm}~ {type} \\to {dhcp} \\to {distorted} fcc (hcp: hexagonal close packed; fcc: face centered cubic; dhcp: double hcp) is observed in Er below 58 GPa. We have carried out Rietveld refinement of crystal structures in the pressure range between 58 GPa and 151 GPa. We have examined various crystal structures that have been proposed for the distorted fcc (dfcc) phase and the post-dfcc phase in rare earth metals. We find that the hexagonal hR 24 structure is the best fit between 58 and 118 GPa. Above 118 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.9%. We have also established a clear trend for the pressure at which a post-dfcc phase is formed in rare earth metals and show that there is a monotonic increase in this pressure with the filling of 4f shell.

Samudrala, Gopi K.; Thomas, Sarah A.; Montgomery, Jeffrey M.; Vohra, Yogesh K.

2011-08-01

56

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

OpenAIRE

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

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

2013-01-01

57

Center of pressure control for balance maintenance during lateral waist-pull perturbations in older adults.  

Science.gov (United States)

When balance is disturbed, location of the center of pressure (COP) contributes to a person's ability to recover from a perturbation. This study investigated COP control prior to first step lift-off (FSLO) during lateral perturbations in older non-fallers and fallers. 38 non-fallers and 16 fallers received lateral waist-pulls at 5 different intensities. Crossover stepping responses at the intensity level where the largest number of subjects responded with crossover steps were analyzed. Whole-body center of mass (COM) and COP positions in the medio-lateral (ML) direction with respect to the base of support (BOS), and COP velocity were calculated. An inverted pendulum model was used to define the BOS stability boundary at FSLO, which was also adjusted using the COP position at FSLO (functional boundary). No significant differences were found in the COP velocities between fallers and non-fallers (p>.093). However, the COP positions for fallers were located significantly more medial at FSLO (p?.01), resulting in a significantly reduced functional boundary. Although the stability margins, measures of stability based on the BOS, were significantly larger than zero for fallers (p?.004), they were not significantly different from zero for the functional boundary, i.e., reaching the functional stability limit. Fallers had reduced functional limits of stability in the ML direction, which would predispose them to more precarious stability conditions than non-fallers. This could be a cause for taking more steps than non-fallers for balance recovery as we observed. The functional boundary estimation may be a more sensitive marker of balance instability than the BOS boundary. PMID:25728580

Fujimoto, Masahiro; Bair, Woei-Nan; Rogers, Mark W

2015-04-13

58

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

59

Center of pressure (COP) during the Postural Balance Control of High-Heeled Woman.  

Science.gov (United States)

This study addressed the effect of balance control problems of the high-heeled women. Clinical relationships have been proposed linking foot ailments or pain to wearing high heels, yet little quantitative research has been done on the relationship between bare foot and high feeled foot. The purposes of this study were to objectively quantify the displacements and velocities of center-of- pressure (COP) of body during two-way waist pulling and to compare the differences between barefooted and high-heeled situations. We used a waist pulling system which has three different magnitudes to sway the subjects. We found that the kinematic information of barefooted and high-heeled women's COP is very important in understanding the mechanism of postural balance control of women in every-day life. In the high-heeled's case, the displacement of COP increases in 200% as against bare footed. Also the velocity variation of COP grows two times than the bare footed. PMID:17282813

Cho, W; Choi, H

2005-01-01

60

Effect of pressure on the coordination structure of acetate-rare earth complex in water  

International Nuclear Information System (INIS)

Pressure-induced coordination structural changes of the acetate-rare earth complex in water (LnCl3·20H2O·CH3COOLi) have been investigated using Raman spectroscopy. From the analysis of Raman CC stretching band of acetate ion, the integrated Raman intensity of polymeric chain structure decreases with increasing pressure throughout the rare-earth series. The monodentate ligand appears at around 0.6 GPa in the meddle-heavy rare earth region. We have determined the difference in the partial molar volume (PMV) (?V) among three coordination structures. The rank ordering of the PMV of three coordination structures is as follows: monodentate ligand Polymeric? Bidentate and ?VBidentate?Monodentate become larger with decreasing ionic radius of Ln3+ ion, and theses are probably due to the size effect of Ln3+ ion.

61

Effect of pressure on the coordination structure of acetate-rare earth complex in water  

Science.gov (United States)

Pressure-induced coordination structural changes of the acetate-rare earth complex in water (LnCl3·20H2O·CH3COOLi) have been investigated using Raman spectroscopy. From the analysis of Raman CC stretching band of acetate ion, the integrated Raman intensity of polymeric chain structure decreases with increasing pressure throughout the rare-earth series. The monodentate ligand appears at around 0.6 GPa in the meddle-heavy rare earth region. We have determined the difference in the partial molar volume (PMV) (?V) among three coordination structures. The rank ordering of the PMV of three coordination structures is as follows: monodentate ligand

Nakajima, K.; Shimizu, A.; Takekiyo, T.; Yoshimura, Y.; Koizumi, T.

2010-03-01

62

Energy balance and pressure in the solar transition zone for network and active region features  

International Nuclear Information System (INIS)

The pressure and energy balance in the solar transition zone are determined for about 125 network and active region features from new high spectral (0.06 A) and spatial (1'') resolution extreme-ultraviolet spectra. New plasma diagnostics consisting of Si III line intensity ratios are used to find the electron density N, and pressure P/sub e/ near 3.5 x 104 K, the temperature where Si III is most abundant. The observed Si III line intensity ratios, R (1301/1312) and R (1301/1296), are compared with theoretical calculations for these ratios as functions of density and temperature. From this comparison, electron densities ranging from 2 x 1010 cm-3 at 2000 km above the limb to 10 12 cm-3 in an active region are derived. The energy losses due to radiation are compared with two energy source terms, conductive flux and turbulent energy dissipation. The radiative losses are proportional only to P/sub e/2. However, the divergence of the conductive flux is a function of the fill factor a and the average temperature gradient in the line of sight , and the turbulent energy dissipation is a function of a and P/sub e/. P/sub e/ and can be found from plasma diagnostics and emission line intensities, but values of a must be derived by assuming the spatial extent of the transition zone plasma along the line of sight.In an extreme case a=1 for a plane-parallel homogeneous transition zone, and the divergomogeneous transition zone, and the divergence of the conductive flux and turbulent energy dissipation balance the radiative losses

63

Earth Observation Plan Looks Toward Balancing U.S. Federal Priorities  

Science.gov (United States)

The U.S. federal government funds about 2.5 billion for Earth observation satellite systems and more than 1 billion for airborne, terrestrial (including freshwater), and marine networks and surveys among 11 departments and agencies. Combined, those Earth observation activities add about $30 billion to the U.S. economy each year.

Showstack, Randy

2014-08-01

64

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-04-01

65

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

International Nuclear Information System (INIS)

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-1 Hz-1/2 is preserved down to frequencies of several Hz even after strong motion in the Earth's magnetic field

66

Dietary potassium and the renal control of salt balance and blood pressure.  

Science.gov (United States)

Dietary potassium (K(+)) intake has antihypertensive effects, prevents strokes, and improves cardiovascular outcomes. The underlying mechanism for these beneficial effects of high K(+) diets may include vasodilation, enhanced urine flow, reduced renal renin release, and negative sodium (Na(+)) balance. Indeed, several studies demonstrate that dietary K(+) intake induces renal Na(+) loss despite elevated plasma aldosterone. This review briefly highlights the epidemiological and experimental evidences for the effects of dietary K(+) on arterial blood pressure. It discusses the pivotal role of the renal distal tubule for the regulation of urinary K(+) and Na(+) excretion and blood pressure and highlights that it depends on the coordinated interaction of different nephron portions, epithelial cell types, and various ion channels, transporters, and ATPases. Moreover, we discuss the relevance of aldosterone and aldosterone-independent factors in mediating the effects of an altered K(+) intake on renal K(+) and Na(+) handling. Particular focus is given to findings suggesting that an aldosterone-independent downregulation of the thiazide-sensitive NaCl cotransporter significantly contributes to the natriuretic and antihypertensive effect of a K(+)-rich diet. Last but not least, we refer to the complex signaling pathways enabling the kidney to adapt its function to the homeostatic needs in response to an altered K(+) intake. Future work will have to further address the underlying cellular and molecular mechanism and to elucidate, among others, how an altered dietary K(+) intake is sensed and how this signal is transmitted to the different epithelial cells lining the distal tubule. PMID:25559844

Penton, David; Czogalla, Jan; Loffing, Johannes

2015-03-01

67

Electronic and optical properties of distorted rare-earth manganite under hydrostatic pressure  

Science.gov (United States)

The effect of hydrostatic pressure on the crystal structure, electronic and optical properties of distorted rare-earth manganite TbMnO3 has been studied on the basis of first-principle calculations. The results reveal that the band gaps reduce quadratically with increasing pressure. The optical properties of TbMnO3 predict that the peaks in the dielectric function shift to higher photon energy due to the transformation of inner electronic states with increasing pressure. Otherwise, the peaks in the reflectivity spectra and loss function were also found to move to higher photon energy with pressure increasing and the relationships between the positions of these peaks and pressure can be fitted by third order polynomial expressions.

Cai, L.-G.; Liu, F.-M.; Zhang, D.; Zhong, W.-W.

2012-06-01

68

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

69

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 subjectared 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)

70

A rightly balanced intellectual property rights regime as a mechanism to enhance commercial earth observation activities  

Science.gov (United States)

Earth observation by satellites is one of the developing sectors of space activities with the growing involvement in private capital or actors. This leads to the question of how efficient legal rules governing this activity are. Copyright law is one of the key fields of law applicable to earth observation activities and is the subject of the present analysis. This paper describes the current state of copyright regulations in different jurisdictions. It also addresses the issue of defining earth observation data for the purpose of applying copyright protection to them. Finally, it analyses whether more or less copyright protection would be beneficial for the commercialisation of the earth observation activities, and the distribution and further use of data they produce. The paper is largely based on my current doctoral research. Draft chapter on file with the author.

Doldirina, Catherine

2010-09-01

71

High-pressure phase transitions in rare earth metal thulium to 195 GPa  

Science.gov (United States)

We have performed image plate x-ray diffraction studies on a heavy rare earth metal, thulium (Tm), in a diamond anvil cell to a pressure of 195 GPa and volume compression V/Vo = 0.38 at room temperature. The rare earth crystal structure sequence, {hcp}\\to {Sm {-}type} \\to {dhcp} \\to {fcc} \\to distorted fcc, is observed in Tm below 70 GPa with the exception of a pure fcc phase. The focus of our study is on the ultrahigh-pressure phase transition and Rietveld refinement of crystal structures in the pressure range between 70 and 195 GPa. The hexagonal hR- 24 phase is seen to describe the distorted fcc phase between 70 and 124 GPa. Above 124 ± 4 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.5%. The equation of state data shows rapid stiffening above the phase transition at 124 GPa and is indicative of participation of f-electrons in bonding. We compare the behavior of Tm to other heavy rare-earths and heavy actinide metals under extreme conditions of pressure.

Montgomery, Jeffrey M.; Samudrala, Gopi K.; Tsoi, Georgiy M.; Vohra, Yogesh K.

2011-04-01

72

High-pressure phase transitions in rare earth metal thulium to 195 GPa  

Energy Technology Data Exchange (ETDEWEB)

We have performed image plate x-ray diffraction studies on a heavy rare earth metal, thulium (Tm), in a diamond anvil cell to a pressure of 195 GPa and volume compression V/V{sub o} = 0.38 at room temperature. The rare earth crystal structure sequence, hcp {yields} Sm-type {yields} dhcp {yields} fcc {yields} distorted fcc, is observed in Tm below 70 GPa with the exception of a pure fcc phase. The focus of our study is on the ultrahigh-pressure phase transition and Rietveld refinement of crystal structures in the pressure range between 70 and 195 GPa. The hexagonal hR- 24 phase is seen to describe the distorted fcc phase between 70 and 124 GPa. Above 124 {+-} 4 GPa, a structural transformation from hR 24 phase to a monoclinic C 2/m phase is observed with a volume change of - 1.5%. The equation of state data shows rapid stiffening above the phase transition at 124 GPa and is indicative of participation of f-electrons in bonding. We compare the behavior of Tm to other heavy rare-earths and heavy actinide metals under extreme conditions of pressure.

Montgomery, Jeffrey M; Samudrala, Gopi K; Tsoi, Georgiy M; Vohra, Yogesh K [Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294 (United States)

2011-04-20

73

Smoothly waning, symmetrically expanding, cavity-pressure loads in earth materials  

International Nuclear Information System (INIS)

An approximate solution for the pressure loading required to expand a spherical cavity in rock and soil targets is derived. A dual characterization of fracture and flow material model is used. Frictional resistance to flow is also included. Non-linear volumetric strain hardening is modeled with bi-linear curves and unloading is assumed to be non-dilative. Applications of this solution form to the prediction of pressure loading on slender, convex-nosed earth penetrators and on spherically-nosed water entry vehicles are discussed

74

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

75

Modeling long-term changes in forested landscapes and their relation to the Earth's energy balance  

Science.gov (United States)

The dynamics of the forested parts of the Earth's surface on time scales from decades to centuries are discussed. A set of computer models developed at Oak Ridge National Laboratory and elsewhere are applied as tools. These models simulate a landscape by duplicating the dynamics of growth, death and birth of each tree living on a 0.10 ha element of the landscape. This spatial unit is generally referred to as a gap in the case of the forest models. The models were tested against and applied to a diverse array of forests and appear to provide a reasonable representation for investigating forest-cover dynamics. Because of the climate linkage, one important test is the reconstruction of paleo-landscapes. Detailed reconstructions of changes in vegetation in response to changes in climate are crucial to understanding the association of the Earth's vegetation and climate and the response of the vegetation to climate change.

Shugart, H. H.; Emanuel, W. R.; Solomon, A. M.

1984-01-01

76

Estuaries: Finding the Balance  

Science.gov (United States)

This lesson will examine the conflict between development and the environment, and the attempts for a sound compromise while still helping the earth sustain the economic growth, expansion, and pressure we are exerting on its natural resources. Using estuaries as a case study, students will be encouraged to consider the interaction between environmental and economic demands, and to seek a balance that will protect both the estuarine habitat and economic growth.

77

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

Energy Technology Data Exchange (ETDEWEB)

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

Stamenkovic, Vlada; Noack, Lena; Spohn, Tilman [Institute of Planetology, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Breuer, Doris, E-mail: Vlada.Stamenkovic@dlr.de, E-mail: Lena.Noack@dlr.de, E-mail: Doris.Breuer@dlr.de, E-mail: Tilman.Spohn@dlr.de [Institute of Planetary Research, German Aerospace Center DLR, Rutherfordstrasse 2, 12489 Berlin (Germany)

2012-03-20

78

Effect of pressure on the coordination structure of acetate-rare earth complex in water  

Energy Technology Data Exchange (ETDEWEB)

Pressure-induced coordination structural changes of the acetate-rare earth complex in water (LnCl{sub 3{center_dot}}20H{sub 2}O{center_dot}CH{sub 3}COOLi) have been investigated using Raman spectroscopy. From the analysis of Raman CC stretching band of acetate ion, the integrated Raman intensity of polymeric chain structure decreases with increasing pressure throughout the rare-earth series. The monodentate ligand appears at around 0.6 GPa in the meddle-heavy rare earth region. We have determined the difference in the partial molar volume (PMV) ({Delta}V) among three coordination structures. The rank ordering of the PMV of three coordination structures is as follows: monodentate ligand

Nakajima, K; Shimizu, A [Department of Environmental Engineering for Symbiosis, Soka University, 1-326 Tangi-cho, Hachioji, Tokyo, 192-8577 (Japan); Takekiyo, T; Yoshimura, Y; Koizumi, T, E-mail: take214@nda.ac.j [Department of Applied Chemistry, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa, 239-8686 (Japan)

2010-03-01

79

Iron under Earth’s core conditions: Liquid-state thermodynamics and high-pressure melting curve from ab initio calculations  

OpenAIRE

Ab initio techniques based on density functional theory in the projector-augmented-wave implementation are used to calculate the free energy and a range of other thermodynamic properties of liquid iron at high pressures and temperatures relevant to the Earth’s core. The ab initio free energy is obtained by using thermodynamic integration to calculate the change of free energy on going from a simple reference system to the ab initio system, with thermal averages computed by ab initio molecul...

Alfe, D.; Price, G. D.; Gillan, M. J.

2002-01-01

80

Prediction of Satellite Motion under the Effects of the Earth’s Gravity, Drag Force and Solar Radiation Pressure in terms of the KS-regularized Variables  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is concerned with an orbit prediction using one of the best regular theories (KS-regularized variables. Perturbations due to the Earth’s gravitational field with axial symmetry up to the fourth order zonal harmonic, atmospheric drag (variation in density model with height and solar radiation pressure are considered. Applications of the problem with a comparison between the perturbations effect will be illustrated by numerical and graphical example.

Hany R. Dwidar

2014-06-01

81

Modelling the rheology of MgO under Earth's mantle pressure, temperature and strain rates.  

Science.gov (United States)

Plate tectonics, which shapes the surface of Earth, is the result of solid-state convection in Earth's mantle over billions of years. Simply driven by buoyancy forces, mantle convection is complicated by the nature of the convecting materials, which are not fluids but polycrystalline rocks. Crystalline materials can flow as the result of the motion of defects--point defects, dislocations, grain boundaries and so on. Reproducing in the laboratory the extreme deformation conditions of the mantle is extremely challenging. In particular, experimental strain rates are at least six orders of magnitude larger than in nature. Here we show that the rheology of MgO at the pressure, temperature and strain rates of the mantle is accessible by multiscale numerical modelling starting from first principles and with no adjustable parameters. Our results demonstrate that extremely low strain rates counteract the influence of pressure. In the mantle, MgO deforms in the athermal regime and this leads to a very weak phase. It is only in the lowermost lower mantle that the pressure effect could dominate and that, under the influence of lattice friction, a viscosity of the order of 10(21)-10(22) pascal seconds can be defined for MgO. PMID:22237109

Cordier, Patrick; Amodeo, Jonathan; Carrez, Philippe

2012-01-12

82

Effect of pressure on the electrical resistivities of some ternary rare earth compounds  

International Nuclear Information System (INIS)

Electrical resistance of sintered samples of ternary compounds of the rare earths having tI 10 ThCu2Si2 structure are determined from measurements in an Bridgman anvil apparatus upto 80 kbar. The resistance measurements were performed using d.c. four-probe technique. In CeCu2Si2 and YbCu2Si2 the rare earth atom is known to exist in an intermediate valence state and in compounds CeAu2Si2 and CeAg2Si2 it is expected to go over to an intermediate valence state on application of pressure. Such a valence state transition is not expected in LaCu2Si2. In LaSi2Cu2 the resistance drop is small. In all cerium compounds the small initial drop is followed by an increase in resistance at high pressures due to the magnetic contribution, while in other compounds it remains constant. Large resistance drop in compounds CeCu2Si2 and YbCu2Si2 may be indicative of a valence change transition under pressure. (auth.)

83

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

International Nuclear Information System (INIS)

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

84

Pressure-induced valence change in the rare earth metals:The case of Praseodymium  

OpenAIRE

The rare earth metal praseodymium (Pr) transforms from the d-fcc crystal structure (Pr-III) to {$\\alpha$}-U one (Pr-IV) at 20 GPa with a large volume collapse (${\\rm\\Delta} V/V$ = 0.16), which is associated with the valence change of the Pr ion. The two 4{\\it f} electrons in the Pr ion is supposed to be itinerant in the Pr-IV phase. In order to investigate the electronic state of the phase IV, we performed the high pressure electrical resistance measurement using the diamond...

Tateiwa, Naoyuki; Nakagawa, Akitoshi; Fujio, Kazuhiko; Kawae, Tatsuya; Takeda, Kazuyoshi

2005-01-01

85

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

86

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

87

High Pressure Effects on the Superconductivity in Rare-Earth Doped CaFe2As2  

OpenAIRE

High-pressure superconductivity in a rare-earth doped Ca0.86Pr0.14Fe2As2 single crystalline sample has been studied up to 12 GPa and temperatures down to 11 K using designer diamond anvil cell under a quasi-hydrostatic pressure medium. The electrical resistance measurements were complemented by high pressure and low temperature x-ray diffraction studies at a synchrotron source. The electrical resistance measurements show an intriguing observation of superconductivity under p...

Cargill, Dan; Uhoya, Walter; Krzysztof, Gofryk; Tsoi, Georgiy M.; Vohra, Yogesh K.; Sefat, Athena S.; Weir, S. T.

2013-01-01

88

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

89

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

Science.gov (United States)

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

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

2013-07-01

90

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

91

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.

92

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

Science.gov (United States)

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 & 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 & measurement conditions (for gauge and absolute pressure measurements), uncertainty budget preparation and evaluation of measurement uncertainty are discussed in detail in this paper.

Vijayakumar, D. Arun; Prakash, Om; Sharma, R. K.

2012-11-01

93

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)

94

Fractionation of rare earths and yttrium in fluid-magma systems under high pressures (from experimental data)  

International Nuclear Information System (INIS)

The distribution of rare earth elements (La-Nd, Sm-Lu) and yttrium between water-chloride fluids and ultrabasic at T-1100 deg C and T-1200 deg C within the range of P=1-14 kbar is experimentally studied for the purpose of evaluating the behaviour of rare earth elements in magmatic processes under high pressures. It is shown that under such conditions the fluid phase is enriched by the heavy rare earth elements and the coexicting melt by the light ones. The pressure dependence of distribution coefficients of rare earths and yttrium in the fluid-melt systems is of extremal character with a minimum at P=5 kbar

95

Earth  

Science.gov (United States)

This lithograph depicts a view of Earth taken from Apollo 10 during its journey to the Moon in May 1969. False-color satellite images showing chlorophyll concentration, sea surface temperature, topography, and ozone concentration are also featured. The images are accompanied by a brief description, some statistical facts, and a list of important dates in the history of Earth exploration.

96

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

International Nuclear Information System (INIS)

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

97

Iron under Earth's core conditions Liquid-state thermodynamics and high-pressure melting curve  

CERN Document Server

{\\em Ab initio} techniques based on density functional theory in the projector-augmented-wave implementation are used to calculate the free energy and a range of other thermodynamic properties of liquid iron at high pressures and temperatures relevant to the Earth's core. The {\\em ab initio} free energy is obtained by using thermodynamic integration to calculate the change of free energy on going from a simple reference system to the {\\em ab initio} system, with thermal averages computed by {\\em ab initio} molecular dynamics simulation. The reference system consists of the inverse-power pair-potential model used in previous work. The liquid-state free energy is combined with the free energy of hexagonal close packed Fe calculated earlier using identical {\\em ab initio} techniques to obtain the melting curve and volume and entropy of melting. Comparisons of the calculated melting properties with experimental measurement and with other recent {\\em ab initio} predictions are presented. Experiment-theory comparis...

Alfe`, D; Gillan, M J

2001-01-01

98

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

Science.gov (United States)

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

Zerbini, S.

1980-01-01

99

Carbon content in the Earth's inner core from the elasticity of iron carbide at high pressure  

Science.gov (United States)

Discrepancy between sound wave velocity of Fe-Ni alloys and seismological models indicate that Earth’s core is likely to contain lighter elements such as H, C, O, Si and S. Carbon is a plausible candidate because of its cosmic abundance and chemical affinity to iron at low pressures. Earlier it was thought that carbon, being volatile might have been lost during the accretionary stages of the planet. However, it is now known, that core formation likely took place from the deep magma ocean surrounded by solar-nebula type proto-atmosphere enriched in volatiles thus enabling incorporation of volatiles in to the molten core. Experimental studies conducted to study the phase diagram of Fe-C system revealed that volatility of carbon is only significant at pressures lower than 10-5 GPa. (Wood, 1993, EPSL, 117, 593) suggested that solid inner core might be composed of Fe3C. Recent experimental studies have extended the Fe-C phase diagram to considerably higher pressures (~70 GPa) and have found that Fe7C3 is the likely phase at the inner core conditions (Lord et al., 2009, EPSL, 284, 157). In this study we determine the elasticity of Fe7C3 using first principle methods. Results of compression for the ferromagnetic Fe7C3 is well represented by a third order Birch Murnaghan finite strain expression with K0~ 275 GPa, K?~2.5 and V0~ 182 Å3. Under compression magnetic moment gradually decreases and at ~69 GPa magnetic moment is instantaneously lost. Similar behavior has been reported for Fe3C at 60 GPa (Vocadlo et al., 2002, EPSL, 203, 567). The high-pressure non-magnetic phase has distinct elastic parameters with K0~ 228 GPa, K?~4.9 and V0~ 181 Å3. Calculated elastic constants also exhibit softening associated with the loss of magnetization. Similar anomalous behavior in thermoelastic parameter owing to loss of magnetization has been observed for Fe3C (Fiquet et al. 2009, PEPI, 172, 125) at 68 GPa. We will present full elastic tensor and sound wave velocity results for ferromagnetic and non-magnetic phase and infer about the carbon content of the inner core.

Steinle-Neumann, G.; Mookherjee, M.

2009-12-01

100

The importance of plasma colloid osmotic pressure for interstitial fluid volume and fluid balance after elective abdominal vascular surgery.  

Science.gov (United States)

The relationships between plasma colloid osmotic pressure (COPp) and interstitial fluid volume (IFV) as well as postoperative fluid balance were investigated in a prospective study involving 53 patients undergoing elective abdominal aortic reconstruction. The patients were divided into four groups according to pre- and postoperative blood replacement and fluid therapy programs whereby a continuum of postoperative COPp-values between 33 and 16 mmHg was obtained. Measurements were done before the operation and on days 1 and 4 after surgery. After surgery, COPp below 20 mmHg led to increased IFV. On day 1, COPp was linearly correlated to the total amount of fluid retained during the day of operation. A positive fluid balance of 3 L on this day ensured unchanged extracellular fluid volume (ECV). Of the 3 L, 1.5 L was insensible water loss and 1.5 L had moved into the cells. On day 4 after surgery, COPp below 22 mmHg was associated with increased plasma volume. The authors suggest that COPp be maintained above 20 mmHg after major surgery, and positive fluid balance should not exceed 5 L during the day of operation. PMID:3942418

Nielsen, O M; Engell, H C

1986-01-01

101

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

Science.gov (United States)

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

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

2006-03-01

102

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-09-01

103

Experimental validation of a millimeter wave radar technique to remotely sense atmospheric pressure at the Earth's surface  

Science.gov (United States)

Experiments with a millimeter wave radar operating on the NASA CV-990 aircraft which validate the technique for remotely sensing atmospheric pressure at the Earth's surface are described. Measurements show that the precise millimeter wave observations needed to deduce pressure from space with an accuracy of 1 mb are possible, that sea surface reflection properties agree with theory and that the measured variation of differential absorption with altitude corresponds to that expected from spectroscopic models.

Flower, D. A.; Peckham, G. E.; Bradford, W. J.

1984-01-01

104

Potassium modulates electrolyte balance and blood pressure through effects on distal cell voltage and chloride.  

Science.gov (United States)

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

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

2015-01-01

105

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

106

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

107

Universal viscosity growth in metallic melts at megabar pressures: the vitreous state of the Earth's inner core  

International Nuclear Information System (INIS)

Experimental data on and theoretical models for the viscosity of various types of liquids and melts under pressure are reviewed. Experimentally, the least studied melts are those of metals, whose viscosity is considered to be virtually constant along the melting curve. The authors' new approach to the viscosity of melts involves the measurement of the grain size in solidified samples. Measurements on liquid metals at pressures up to 10 GPa using this method show, contrary to the empirical approach, that the melt viscosity grows considerably along the melting curves. Based on the experimental data and on the critical analysis of current theories, a hypothesis of a universal viscosity behavior is introduced for liquids under pressure. Extrapolating the liquid iron results to the pressures and temperatures at the Earth's core reveals that the Earth's outer core is a very viscous melt with viscosity values ranging from 102 Pa s to 1011 Pa s depending on the depth. The Earth's inner core is presumably an ultraviscous (>1011 Pa s) glass-like liquid - in disagreement with the current idea of a crystalline inner core. The notion of the highly viscous interior of celestial bodies sheds light on many mysteries of planetary geophysics and astronomy. From the analysis of the pressure variation of the melting and glass-transition temperatures, an entirely new concept of a stable metallic vitreous state arises, calling for further experimental and tes, calling for further experimental and theoretical study. (reviews of topical problems)

108

Pressure-induced valence change in the rare earth metals:The case of Praseodymium  

CERN Document Server

The rare earth metal praseodymium (Pr) transforms from the d-fcc crystal structure (Pr-III) to {$\\alpha$}-U one (Pr-IV) at 20 GPa with a large volume collapse (${\\rm\\Delta} V/V$ = 0.16), which is associated with the valence change of the Pr ion. The two 4{\\it f} electrons in the Pr ion is supposed to be itinerant in the Pr-IV phase. In order to investigate the electronic state of the phase IV, we performed the high pressure electrical resistance measurement using the diamond anvil cell up to 32 GPa. In the Pr-IV phase, the temperature dependence of the resistance shows an upward negative curvature, which is similar to the itinerant 5{\\it f} electron system in actinide metals and compounds. This suggests the narrow quasiparticle band of the 4{\\it f} electrons near the Fermi energy. A new phase boundary is found at $T_{0}$ in the Pr-IV phase. From the temperature and magnetic field dependences of the resistance at 26 GPa, the ground state of the Pr-IV phase is suggested to be magnetic. Several possibilities for...

Tateiwa, N; Fujio, K; Kawae, T; Takeda, K; Tateiwa, Naoyuki; Nakagawa, Akitoshi; Fujio, Kazuhiko; Kawae, Tatsuya; Takeda, Kazuyoshi

2005-01-01

109

The temperature structure and pressure balance of magnetic loops in active regions  

International Nuclear Information System (INIS)

EUV observations show many active region loops in lines formed at temperatures between 104K and 2X106K. The brightest loops are associated with flux tubes leading to the umbrae of sunspots. It is shown that the high visibility of certain loops in transition region lines is due principally to a sharp radial decrease of temperature to chromospheric values toward the loop axis. The plasma density of these cool loops is not significantly greater than in the hot gas immediately surrounding it. Consequently, the internal gas pressure of the cool material is clearly lower. The hot material immediately surrounding the cool loops is generally denser than the external corona by a factor 3-4. When the active region is examined in coronal lines, this hot high pressure plasma shows up as loops that are generally parallel to the cool loops but significantly displaced laterally. In general the loop phenomenon in an active region is the result of temperature variations by two orders of magnitude and density variations of around a factor five between adjacent flux tubes in the corona. (Auth.)

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

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

112

Effect of pressure on the electric resistivity and Seebeck coefficient of some ternary rare-earth silicides  

International Nuclear Information System (INIS)

The electric resistivity to 100 kbar and the Seebeck coefficient to 50 kbar of some ternary rare-earth compounds belonging to the tetragonal ThCr2Si2 structure are reported. No pressure-induced valence transition was found in PrCu2Si2 and YbCu2Si2. Among the intermediate-valence compounds EuCu2Si2, YbCu2Si2, and CeCu2Si2, the high-pressure behaviour of the cerium compound is found to be different. A continuous valence transition is seen in EuCu2Si2, which reaches completion above 95 kbar. The three compounds CeCu2Si2, CeAg2Si2, and CeAu2Si2 show a resistivity increase at high pressure which is probably due to an increase in the magnetic resistivity with increasing pressure. (author)

113

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

Science.gov (United States)

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

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

2015-02-01

114

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

CERN Document Server

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

Jenkins, Edward B

2008-01-01

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

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

Science.gov (United States)

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

Ware, Lucas Andrew

2015-01-01

117

The pressure induced B1-B2 phase transition of alkaline halides and alkaline earth chalcogenides. A first principles investigation  

International Nuclear Information System (INIS)

In this work, we considered the pressure induced B1-B2 phase transition of AB compounds. The DFT calculations were carried out for 11 alkaline halides, 11 alkaline earth chalcogenides and the lanthanide pnictide CeP. For both the B1 and the B2 structures of each compound, the energy was calculated as a function of the cell volume. The transition pressure, the bulk moduli and their pressure derivatives were obtained from the corresponding equations of state. The transition path of the Buerger mechanism was described using roots of the transition matrix. We correlated the computed enthalpies of activation to some structure defining properties of the compounds. A fair correlation to Pearsons hardness of the ions was observed. -- Graphical abstract: Pressure induced transition from the B1 structure (left) via the transition state (middle) to the B2 structure (right). Display Omitted Highlights: ? Pressure induced phase transitions in AB compounds were considered. ? Alkaline halides and alkaline earth chalcogenides were treated. ? DFT calculations with periodic boundary conditions were applied. ? The transition path was described by roots of the transition matrix. ? The enthalpy of activation was calculated for numerous compounds.

118

Mice carrying ubiquitin-specific protease 2 (Usp2) gene inactivation maintain normal sodium balance and blood pressure.  

Science.gov (United States)

Ubiquitylation plays an important role in the control of Na? homeostasis by the kidney. It is well established that the epithelial Na? channel ENaC is regulated by the ubiquitin-protein ligase NEDD4-2, limiting ENaC cell surface expression and activity. Ubiquitylation can be reversed by the action of deubiquitylating enzymes (DUBs). One such DUB, USP2-45, was identified previously as an aldosterone-induced protein in the kidney and is also a circadian output gene. In heterologous expression systems, USP2-45 binds to ENaC, deubiquitylates it, and enhances channel density and activity at the cell surface. Because the role of USP2-45 in renal Na? transport had not been studied in vivo, we investigated here the effect of Usp2 gene inactivation in this process. We demonstrate first that USP2-45 protein has a rhythmic expression with a peak at ZT12. Usp2-KO mice did not show any differences from wild-type littermates with respect to the diurnal control of Na? or K? urinary excretion and plasma levels either on a standard diet or after acute and chronic changes to low- and high-Na? diets, respectively. Moreover, they had similar aldosterone levels on either a low- or high-Na? diet. Blood pressure measurements using telemetry did not reveal variations compared with control mice. Usp2-KO mice did not display alterations in expression of genes involved in sodium homeostasis or the ubiquitin system, as evidenced by transcriptome analysis in the kidney. Our data suggest that USP2 does not play a primary role in the control of Na? balance or blood pressure. PMID:23552861

Pouly, Daniel; Debonneville, Anne; Ruffieux-Daidié, Dorothée; Maillard, Marc; Abriel, Hugues; Loffing, Johannes; Staub, Olivier

2013-07-01

119

Seasonal Variations of the Earth's Gravitational Field: An Analysis of Atmospheric Pressure, Ocean Tidal, and Surface Water Excitation  

Science.gov (United States)

Monthly mean gravitational field parameters (denoted here as C(sub even)) that represent linear combinations of the primarily even degree zonal spherical harmonic coefficients of the Earth's gravitational field have been recovered using LAGEOS I data and are compared with those derived from gridded global surface pressure data of the National meteorological center (NMC) spanning 1983-1992. The effect of equilibrium ocean tides and surface water variations are also considered. Atmospheric pressure and surface water fluctuations are shown to be the dominant cause of observed annual C(sub even) variations. Closure with observations is seen at the 1sigma level when atmospheric pressure, ocean tide and surface water effects are include. Equilibrium ocean tides are shown to be the main source of excitation at the semiannual period with closure at the 1sigma level seen when both atmospheric pressure and ocean tide effects are included. The inverted barometer (IB) case is shown to give the best agreement with the observation series. The potential of the observed C(sub even) variations for monitoring mass variations in the polar regions of the Earth and the effect of the land-ocean mask in the IB calculation are discussed.

Dong, D,; Gross, R.S.; Dickey, J.

1996-01-01

120

Pressure-induced structural phase transition and elastic properties in rare earth CeBi and LaBi  

International Nuclear Information System (INIS)

Pressure is one of the external parameters by which the interplay of the f-electrons with the normal conduction electrons may be varied. At ambient conditions the rare-earth compounds are characterized by a fixed fn configuration of atomic-like f-electrons, but the decreased lattice spacing resulting from the application of pressure eventually leads to the destabilization of the f-shell. The theoretical description of this electronic transition remains a challenge. The present study reports a comprehensive study on structural, electronic band structures, elastic and lattice dynamical properties of rare earth monopnictides CeBi and LaBi using first principles density functional calculations within the pseudopotential approximation. Both compounds possess NaCI (B1) structure at ambient pressure and transform either to CsCI or body centered tetragonal (BCT) structure. Our results concerning equilibrium lattice parameter and bulk modulus agree well with the available experimental and previous theoretical data. The volume change at the crystallographic transition is attributed to a decrease of the cerium valence or a lowering of the p-f hybridization due to the larger interatomic distances in both high pressure phases. The equation of state for rare earth bismuth compounds are calculated and compared with available experimental results. From the total energy and relative volume one can clearly see the relative stabilities of the high pressure phases of both comps of the high pressure phases of both compounds. As the primitive tetragonal phase of both compounds. As the primitive tetragonal phase can be viewed as a CsCl structure, one may think of a transition from B1 to B2. We have also calculated band structure for both phase and here we have presented for B1 case. The narrow bands originating above the Fermi level are mainly due to Ce 'f'-like states, and the major contribution to the density of states is mainly from Ce 'd'-like states. Furthermore, in high-pressure CsCI phase, there is an appreciable hybridization between Ce 'd'-like and 'f'-states

121

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

Science.gov (United States)

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

Vogl, D. F.; Biernat, H. K.; Erkaev, N. V.; Farrugia, C. J.; Mühlbachler, S.

122

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

Directory of Open Access Journals (Sweden)

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

D. F. Vogl

2001-01-01

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

PuBr3-type as high pressure modification of rare earth trihalides LnX3 (X = Cl, Br, I)  

International Nuclear Information System (INIS)

High pressure experiments in a belt-type apparatus were performed on rare earth trichlorides, -bromides and -iodides. The results underline the importance of the PuBr3-type arrangement. The range of existence of this structure type is considerably increased under pressure. X-ray high temperature investigations at ambient pressure on the quenched high pressure phases show a marked correlation between the transformation pressures, which rise with smaller cations, and the temperatures at which the high pressure phases are reconverted to the thermodynamically stable ones. (author)

125

Lattice Vibrations and Electronic Transitions in the Rare-Earth Metals: Praseodymium under Pressure  

Science.gov (United States)

Praseodymium was investigated by Raman spectroscopy under pressure. A negative pressure shift of the E2g mode is observed in the dhcp phase, which indicates that the initial structural sequence hcp?Sm-type?dhcp?fcc as a whole in the regular lanthanides is associated with a softening of this mode. The pressure response of the phonon modes, observed in the monoclinic and ?-uranium phases, where 4f bonding becomes important, is characteristic for anisotropic bonding properties.

Olijnyk, Helmut; Grosshans, Walter A.; Jephcoat, Andrew P.

2004-12-01

126

Climate studies from satellite observations - Special problems in the verification of earth radiation balance, cloud climatology, and related climate experiments  

Science.gov (United States)

A body of techniques that have been developed and planned for use during the Earth Radiation Budget Experiment (ERBE), the International Satellite Cloud Climatology Project (ISCCP), and related climate experiments of the 1980's are reviewed. Validation and verification methods must apply for systems of satellites. They include: (1) use of a normalization or intercalibration satellite, (2) special intensive observation areas located over ground-truth sites, and (3) monitoring of sun and earth by several satellites and/or several instruments at the same time. Since each climate application area has a hierarchy of user communities, validation techniques vary from very detailed methods to those that simply assure high relative accuracy in detecting space and time variations for climate studies. It is shown that climate experiments generally require more emphasis on long-term stability and internal consistency of satellite data sets than high absolute accuracy.

Vonder Haar, T. H.

1982-01-01

127

Topex data analysis to infer Earth's rotational fluctuations forced by the oceanic response to atmospheric pressure variations  

Science.gov (United States)

The oceanic response to atmospheric pressure variations is a dynamic response that depends on the frequency and spatial scale of the forcing. In this dissertation, the actual oceanic response is derived from TOPEX satellite altimeter sea-surface height (SSH) observations (1993--2004) on a 4 degree latitude, 8 degree longitude grid corrected for tides, winds and annual variations. The SSH data obtained from Jet Propulsion Laboratory (JPL) website is already corrected for tides. The wind correction values are from the ECCO model, which had been obtained from JPL. The wind correction has been modified by a "Darwin" correction to insure mass conservation. To eliminate the large annual signal, which might otherwise overwhelm the analysis, a sinusoid of annual period and a trend for 12 years have been removed at each grid location. Pressure data were downloaded from AER in spherical harmonic form. For each harmonic of forcing, a Wiener filter---generalized for complex time series---is used to isolate that portion of the sea-surface height within each gridbox location due to pressure forcing. The input to the Wiener filter was the corrected SSH time series at that location and the desired output was the pressure harmonic time series. Based on the reduction of the error between the desired and the actual output, this technique appears to be successful (mostly) in isolating that portion of SSH due to individual spherical harmonic pressure coefficients. This pressure-driven portion of the SSH has been used to calculate the associated oceanic currents. Then the combined effect of pressure forced SSH and associated currents on Earth's rotation---polar motion and change in Earth's spin rate---are calculated. The ocean's response showed a spatial and temporal dependence. The currents due to at least some harmonics of forcing showed higher velocities along East-West direction and seemed to be associated with sectorial harmonics. In contrast, the currents along North-South direction showed peak velocities for zonal harmonics. The rotational effects calculated here are mainly due to the pressure-forced SSH and shows frequency dependence. The excitation due to dynamic barometer shows significant departures from the excitation due to inverted barometer.

Dey, Nirupam

128

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

129

Effect of Intermittent Positive Pressure Ventilation (IPPV) on Acid-Base Balance and Plasma Electrolytes during Isoflurane Anaesthesia in Sulphur-Crested Cockatoos (Cacatua galerita galerita)  

OpenAIRE

The objective of the study was to investigate the effect of Intermittent Positive Pressure Ventilation (IPPV) on acid-base balance and plasma electrolytes during isoflurane anaesthesia in sulphur-crested cockatoos (Cacatua galerita galerita) Anaesthesia was induced in six birds by mask using a T-piece with 3.0% isoflurane. Blood gases, plasma electrolytes, PCV and Total Protein (TP) were monitored for one hour during Spontaneous Ventilation (SV) and IPPV. IPPV was instituted by engaging the p...

Saul Chemonges

2012-01-01

130

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

Science.gov (United States)

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

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

2015-02-01

131

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).

132

A STUDY OF PASSIVE EARTH PRESSURE IN ANISOTROPIC SAND WITH VARIOUS WALL MOVEMENT MODES  

OpenAIRE

This study investigated the effect of anisotropy on passive pressure in sands by developing computer simulation utilizing FLAC code for plane strain condition. A series of wall movement modes was applied namely translation, rotation about a point below the wall, RBT, and rotation about a point above the wall, RTT. From comparisons with other FLAC model in translation mode with isotropic material, the coefficients of passive pressure Kp were similar to each other except for some combinatio...

Muhiddin, Achmad Bakri

2011-01-01

133

Stability and melting of Fe3C at high pressure and temperature: Implication for the carbon in the Earth's core  

Science.gov (United States)

The Earth's core is regarded as an Fe-Ni alloy but its density is lower than that of pure Fe at the core conditions. Therefore, the Earth's core is supposed to contain light elements and carbon is one of the candidates of the light elements to explain the density deficit of the Earth's core. Nakajima et al. (2009) reported the melting temperature of Fe3C up to around 30 GPa based on textual observations, the chemical analysis of the quenched run products and in situ X-ray diffraction experiments using a Kawai-type multi anvil apparatus. Lord et al. (2009) reported melting temperatures of Fe3C up to 70 GPa, which was determined by the temperature plateau during increasing laser power using a laser-heated diamond anvil cell. They also suggested Fe+Fe7C3 is a stable subsolidus phase. There are obvious discrepancies between the melting curve and the stable subsolidus phase reported by Nakajima et al. (2009) and those reported by Lord et al. (2009). In this study, the melting temperatures of Fe3C and a subsolidus phase relation were determined based on in situ X-ray diffraction experiments. This study aims to reveal the stability field of Fe3C and the melting temperature of Fe3C and to discuss the behaviors of carbon in the Earth's core. We have performed experiments using a laser-heated diamond anvil cell combined with in situ X-ray diffraction experiment at BL10XU beamline, SPring-8 synchrotron facility. An NaCl powder and a rhenium or tungsten foil were used for the insulator and gasket, respectively. Melting of the sample was determined by disappearance of the X-ray diffraction peaks. We determined the melting relation of Fe3C up to 145 GPa by in situ X-ray diffraction experiments. Present results are close to Nakajima et al. (2009) up to 30 GPa but become close to that reported by Lord et al. (2009) at higher pressure conditions. The solidus temperature extrapolated to the ICB pressure, 330 GPa, is 5400 K. We also confirmed that Fe3C is stable as a subsolidus phase at least up to 237 GPa and 4100 K. This strongly suggests that Fe3C is a potential candidate of the Earth's inner core although we need further studies at the inner core conditions.

Takahashi, S.; Ohtani, E.; Sakai, T.; Hirao, N.; Ohishi, Y.

2012-12-01

134

Pressure dependence of the intra rare earth generalized binary phase diagram  

International Nuclear Information System (INIS)

A generalized phase diagram for the trivalent intra lanthanide and yttrium-lanthanide binary alloys has been developed previously. The single diagram represents a total of 91 binary phase diagrams. This paper extends this concept to take into account another variable - pressure. The generalized phase diagrams were established at 1, 2, and 4 GPa (10, 20 and 40 kbar). These diagrams clearly show that the b.c.c. phase as a function of pressure disappears in the light lanthanides, and is stabilized in the heavy lanthanides. This dependence can be understood in terms of the d occupation number, which increases with increasing pressure. The generalized phase diagram is also presented as a 250C isothermal section up to pressures of 24 GPa. The use of systematics enables one to calculate the phase relationships of the intra lanthanide alloys at various pressures between 0 and 4 GPa, and to evaluate the reliability of experimental results. Furthermore, an analysis of the pressure dependence of the various transformations indicates that 4f hybridization plays a significant (but probably not the major) role in determining the lanthanide crystal structures. (Auth.)

135

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

136

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.)

137

Comparison of Radiation Pressure Perturbations on Rocket Bodies and Debris at Geosynchronous Earth Orbit  

Science.gov (United States)

Recent research has highlighted the need for physically consistent radiation pressure and Bidirectional Reflectance Distribution Function (BRDF) models. This paper seeks to evaluate the impact of BRDF-consistent radiation pressure models compared to changes in the other BRDF parameters. The differences in orbital position arising because of changes in the shape, attitude, angular rates, BRDF parameters, and radiation pressure model are plotted as a function of time for simulated rocket bodies and debris at geo-synchronous orbit (GEO). The initial position and velocity of the space object is kept fixed, and the orbital position difference between a baseline or-bit and the perturbed orbit are plotted as a function of time. This is similar to how the effects of perturbations have been visualized in the past in commonly used astrodynamics references.

Wetterer, C.; Hill, K.; Jah, M.

2014-09-01

138

3-D Force-balanced Magnetospheric Configurations  

Energy Technology Data Exchange (ETDEWEB)

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.

Sorin Zaharia; C.Z. Cheng; K. Maezawa

2003-02-10

139

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

140

Role of stratospheric ozone in the zonal and seasonal radiative energy balance of the Earth-troposphere system  

International Nuclear Information System (INIS)

The role of ozone in the tropospheric-surface energy balance is discussed in the context of its latitudinally and seasonally varying modulation of solar and longwave energy fluxes. We analyze in detail the various radiative energy inputs to the stratosphere and the radiative fluxes from the stratosphere to the troposphere. We confirm the result of past analyses that, for a uniform change in ozone, the global average perturbation in radiative fluxes to the troposphere and surface is small since the perturbations in solar and infrared fluxes nearly cancel. However, this result probably severely underestimates the contribution of changes in the distribution of ozone to global climate. It is difficult to evaluate the changes in tropospheric radiation needed to determine a change of climate due to a change of O3. Not even the net global average perturbation radiative fluxes to the troposphere can be calculated without knowing the change of the vertical ozone profile, and the vertical and latitudinal variations of the troposphere-surface perturbation heating rates are likely to be more important for climate change than the net global values

141

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

142

The temperature dependence of saturated vapor pressure over alkaline-earth metal pivaloyltrifluoroacetonate complexes  

Science.gov (United States)

The temperature dependences of saturated vapor pressure over M(PTA)2 · 15-crown-5, where M = Ca, Sr, or Ba and PTA is the pivaloyltrifluoroacetonate anion, were studied by the Knudsen effusion method, and the enthalpies of compound sublimation were calculated. Changes in volatility depending on the central metal atom were determined.

Efimova, Yu. A.; Abakumov, G. A.; Petrov, B. I.; Pochekutova, T. S.; Khamylov, V. K.

2008-11-01

143

Upper-bound solutions of three-dimensional passive earth pressures  

OpenAIRE

This paper presents a novel approach to the determination of passive soil pressures: using the upper-bound method within the framework of limit analysistheory. It is based on a three-dimensional, kinematically admissible, rotational, hyperbolical failure mechanism. The failure mechanism is composed of the central and two lateral bodies, which are connected by a common velocity field. This approach is similar to two-dimensional stability analyses, where the log spiral potential failure surface...

S?krabl, Stanislav; Macuh, Borut

2012-01-01

144

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

145

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

146

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

147

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

OpenAIRE

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

148

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

149

The effect of non-stoichiometry at high-pressure: implications for the Earth's mantle mineralogy  

OpenAIRE

A non-stoichiometric sample of spinel with composition T(Mg0.4Al0.6)M(Al1.8?0.2)O4 was investigated by single-crystal X-ray diffraction in situ up to about 8.7 GPa using a diamond anvil cell. The P(V) data were fitted using a third-order Birch–Murnaghan equation of state and the unit-cell volume V0, the bulk modulus KT0 and its first pressure derivative K? were refined simultaneously providing the following coefficients: V0 = 510.34(6) Å3, KT0 = 171(2) GPa, K? = 7.3(6). This KT0 valu...

Bruno, Marco; Prencipe, Mauro

2009-01-01

150

Effects of altered body fluid balance and high blood pressure on the plasma brain natriuretic peptide in rats.  

OpenAIRE

The present study was aimed to investigate the regulatory mechanisms of BNP release. Effects of acute and chronic perturbations in body fluid balance, changes in BP, and regulatory roles of NO and endothelin systems on BNP release were examined in rats. Although acute extracellular volume expansion did not have significant effects on plasma BNP, prolonged high-salt intake increased plasma BNP levels. Plasma BNP levels were also higher in 2K1C rats compared with the control. Although infusion ...

Kim, S. W.; Lee, J. U.; Kim, N. H.; Choi, K. C.

1997-01-01

151

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

152

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

153

Balance Disorders  

Science.gov (United States)

... additional information about balance disorders? What is a balance disorder? A balance disorder is a condition that ... hardship. Top What are the symptoms of a balance disorder? If you have a balance disorder, you ...

154

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

Science.gov (United States)

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

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

2014-11-01

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

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

157

Renal epithelial sodium channel is critical for blood pressure maintenance and sodium balance in the normal late pregnant rat.  

Science.gov (United States)

Normal pregnancy is a state marked by avid sodium retention and plasma volume expansion. Insufficient plasma volume expansion results in the compromised maternal state of intrauterine growth restriction, which afflicts ?5% of all human pregnancies. We have recently shown that renal epithelial sodium channel (ENaC) activity in vivo in the late pregnant (LP) rat is increased. To determine the importance of the renal versus extrarenal ENaC in sodium retention and blood pressure regulation during pregnancy, we have chronically blocked the ENaC pharmacologically with daily subcutaneous injections of benzamil and genetically using intrarenal transfection of ?ENaC short hairpin RNA. Compared with untreated LP control animals, LP rats treated with benzamil retain less sodium and have reduced mean arterial blood pressure. Furthermore, LP rats treated with benzamil had lower maternal body weight gain. Intrarenal transfection of ?ENaC short hairpin RNA versus scrambled small RNA successfully decreased renal ?ENaC mRNA expression in LP rats. Intrarenal transfection of ?ENaC short hairpin RNA reduced maternal sodium retention, body weight gain and pup weight. Redundant physiological systems that protect blood pressure and sodium homeostasis were unable to compensate for the loss of ENaC activity in the pregnant rat. These findings demonstrate that the renal ENaC is necessary for maintaining pregnancy-mediated sodium retention, volume expansion and blood pressure regulation. PMID:24563165

West, Crystal A; Han, Weiquing; Li, Ningjun; Masilamani, Shyama M E

2014-05-01

158

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

Science.gov (United States)

The phase relations of a wide selection of rare earth disilicates have been investigated up to 10 GPa and 1700 °C using piston cylinder and multi-anvil equipment. Single-crystal X-ray structures have been obtained for the following high-pressure phases: (1) La 2.67(SiO 4) 2: monoclinic, space group C2/ m, Z=2, a=9.419(2), b=5.445(1), c=7.214(1) Å, ?=115.71(3)°, R=0.042; disordered Ba 3(PO 4) 2 structure type, with 3× b and 7× b superstructures identified. (2) Ho 8.67(SiO 4) 6(OH) 2: hexagonal, P6 3/ m, Z=1, a=9.3221(4), c=6.7347(2) Å, R=0.026; silicate hydroxyapatite. (3) Lu 2Si 2O 7: tetragonal, P4 12 12, Z=4, a=6.5620(2), c=11.9535(4) Å, R=0.023; type X diorthosilicate structure, and the silicate analogue of tetragonal Er 2Ge 2O 7.

Fleet, Michael E.; Liu, Xiaoyang

2005-11-01

159

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

160

The effect of temperature and pressure on optical absorption spectra of transition zone minerals - Implications for the radiative conductivity of the Earth's interior  

Science.gov (United States)

Optical absorption spectra of high-pressure minerals can be used as indirect tools to calculate radiative conductivities of the Earth’s interior [e.g., 1]. Recent high-pressure studies imply that e.g. ringwoodite, ?-(Mg,Fe)2SiO4, does not become opaque in the near infrared and visible region, as previously assumed, but remains transparent to 21.5 GPa [2]. Therefore, it has been concluded that radiative heat transfer does not necessarily become blocked at high pressures of the mantle and ferromagnesian minerals actually might contribute to the heat flow in the Earth’s interior [2]. However, experimental results on temperature effects on radiative heat transfer are not available. We studied the effect of both, pressure and temperature, on the optical absorption of hydrous Fe-bearing ringwoodite, ?-(Mg,Fe)2SiO4, and hydrous Fe-bearing wadsleyite, ?-(Mg,Fe)2SiO4, which are the main components of the Earth’s transition zone. Gem-quality single-crystals were synthesized at 18 GPa and 1400 °C in a 5000t multianvil apparatus. Crystals were analyzed by Mössbauer and Raman spectroscopy, electron microprobe analysis and single-crystal X-ray diffraction. For optical absorption measurements in the IR - VIS - UV spectral range (400 - 50000 cm-1) 50 µm sized single-crystals of ringwoodite and wadsleyite were double polished to thicknesses of 13 µm and 18 µm, respectively, and loaded in resistively heated diamond-anvil cells with argon as pressure medium. After taking measurements at high pressure and room temperature, ringwoodite was studied at 26 GPa up to 650 °C and wadsleyite spectra were recorded at 16 GPa up to 450 °C. At ambient pressure the absorption spectrum of ringwoodite reveals a crystal field band (Fe2+) at 12075 cm-1, an intervalence charge transfer band (Fe2+ to Fe3+) at 16491 cm-1, and an absorption edge due to ligand-metal charge transfer close to 30000 cm-1. The wadsleyite spectrum is characterized by a similar absorption edge in the VIS-UV range and by two broad bands at ˜10000 cm-1 and ˜15000 cm-1, which are crystal field and intervalence charge transfer band, respectively. With increasing pressure the absorption spectra of both compositions change uniformly, crystal field and intervalence charge transfer bands continuously shift to higher frequencies. This has been observed for ringwoodite [2] but is contrary to earlier presumptions for wadsleyite [3]. Here, we present radiative conductivities calculated from high-pressure/high-temperature optical absorption spectra. Our results support earlier assumptions that transition zone minerals might contribute to radiative heat transfer in the Earth’s mantle. References: [1] Goncharov et al. (2008), McGraw Yearbook Sci. Tech., 242-245. [2] Keppler & Smyth (2005), Am. Mineral., 90 1209-1212. [3] Ross (1997), Phys. Chem. Earth, 22 113-118.

Thomas, S.; Jacobsen, S. D.; Bina, C. R.; Goncharov, A. F.; Frost, D. J.; McCammon, C. A.

2010-12-01

161

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

OpenAIRE

Coupling effects of Earth oblateness and direct solar radiation pressure on the motion of an artificial satellite are evaluated. Secular and periodic terms are retained up to order three and two respectively, where the coefficient of the second zonal harmonic of the geopotential is considered of first order. The solution revealed the existence of secular terms at order three that arises from the couplings between terms, of lower orders, resulting from the solar radiation pr...

Hadia Hassan Selim

2014-01-01

162

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

Science.gov (United States)

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

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

2014-12-15

163

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

International Nuclear Information System (INIS)

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

164

Structural phase stability of rare earth iron garnet, Gd3Fe5O12 against pressure: in situ X ray diffraction study  

International Nuclear Information System (INIS)

Phase stability of rare earth iron garnet, Gd3Fe5O12, against pressure has been studied using synchrotron based X-ray diffraction measurements. The ambient cubic phase of the compound remains stable up to 30 GPa, the highest pressure of the present investigations. However, beyond 17 GPa a compressibility anomaly is seen. The P-V data up to 17 GPa, when fitted to Birch-Murnaghan equation of state yield a value of bulk modulus as 238.5 GPa with the pressure derivative of bulk modulus fixed at 4. The straight line fit to data beyond 17 GPa gives value of bulk modulus as 278.8 GPa. (author)

165

Russia - Nato. The military balance  

OpenAIRE

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

166

Balance Problems  

Science.gov (United States)

... often, it could be a sign of a balance problem. Balance problems can make you feel unsteady or as ... fall-related injuries, such as hip fracture. Some balance problems are due to problems in the inner ...

167

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 ...

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

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

DEFF Research Database (Denmark)

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

Maribo, Thomas; SchiØttz-Christensen, Berit

2012-01-01

170

Numerical models of caldera-scale volcanic eruptions on Earth, venus, and Mars.  

Science.gov (United States)

Volcanic eruptions of gassy magmas on Earth, Venus, and Mars produce plumes with markedly different fluid dynamics regimes. In large part the differences are caused by the differing atmospheric pressures and ratios of volcanic vent pressure to atmospheric pressure. For each of these planets, numerical simulations of an eruption of magma containing 4 weight percent gas were run on a workstation. On Venus the simulated eruption of a pressure-balanced plume formed a dense fountain over the vent and continuous pyroclastic flows. On Earth and Mars, simulated pressure-balanced plumes produced ash columns, ash falls, and possible small pyroclastic flows. An overpressured plume, illustrated for Mars, exhibited a complex supersonic velocity structure and internal shocks. PMID:17731148

Kieffer, S W

1995-09-01

171

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

172

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

Scientific Electronic Library Online (English)

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

SI, Ribas; ECO, Guirro.

2007-10-01

173

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

Directory of Open Access Journals (Sweden)

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

SI Ribas

2007-10-01

174

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

175

Pressure-induced structural phase transition and elastic properties in rare earth CeBi and LaBi  

Science.gov (United States)

A comprehensive first principles study of structural, elastic, electronic and phonon properties of rare-earth CeBi and LaBi is reported within the density functional theory scheme. The ground state properties such as lattice constant, elastic constants, bulk modulus, and finally the phase transition and lattice dynamical properties of rare-earth CeBi and LaBi of rocksalt (B1) and CsCl (B2) structures are determined. The electron band structures for the two phases of both rare-earth crystals are presented. We have calculated phonon dispersion curve, showing that all phonon modes in phonon dispersion curves of B1 phase in CeBi and LaBi are positive, which indicates a stable phase for this structure.

Mankad, V.; Gupta, S. K.; Lukacevíc, I.; Jha, P. K.

2012-07-01

176

Pressure-induced structural phase transition and elastic properties in rare earth CeBi and LaBi  

International Nuclear Information System (INIS)

A comprehensive first principles study of structural, elastic, electronic and phonon properties of rare-earth CeBi and LaBi is reported within the density functional theory scheme. The ground state properties such as lattice constant, elastic constants, bulk modulus, and finally the phase transition and lattice dynamical properties of rare-earth CeBi and LaBi of rocksalt (B1) and CsCl (B2) structures are determined. The electron band structures for the two phases of both rare-earth crystals are presented. We have calculated phonon dispersion curve, showing that all phonon modes in phonon dispersion curves of B1 phase in CeBi and LaBi are positive, which indicates a stable phase for this structure.

177

Earth materials and earth dynamics  

Energy Technology Data Exchange (ETDEWEB)

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

Bennett, K; Shankland, T. [and others

2000-11-01

178

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

OpenAIRE

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 seventy year old idea of convection in the Earth's fluid core is re...

Herndon, J. Marvin

2009-01-01

179

To what extent can increasing the magnification of visual feedback of the centre of pressure position change the control of quiet standing balance?  

Science.gov (United States)

Previous research has shown that standing sway can be reduced when real-time visual feedback of the centre of pressure (COP) position is provided and that it can be further reduced when the visual feedback is magnified. The objective of this study was to determine the magnification beyond which there was no further change in the control of standing sway, as indicated by measures of the root mean square (RMS) and mean power frequency (MPF) of the COP and COM positions. Participants stood with as little movement as possible on a force platform for 2 min while being provided with visual feedback of their COP position at seven different magnifications (1 x, 4 x, 8 x, 16 x, 32 x, 48 x and 64 x) in two support surface conditions: standing on a foam surface and on a non-compliant surface. The RMS of the COM position decreased while the MPF of the COP position increased with increasing magnification. In the non-compliant surface conditions, these changes reached a plateau when visual feedback was magnified 8 x. When balance was made more difficult by standing on a foam surface, plateaus occurred at larger magnifications and, in some measures, did not reach a plateau at all. These data suggest that: (1) with increasing magnification of visual feedback, small movements of the COP were more easily detected, allowing corrective postural adjustments to be made before accelerations of the COM could lead to large deviations in postural sway and (2) the visual feedback was relied upon to a greater extent when standing on a foam surface. PMID:18996011

Cawsey, Ryan P; Chua, Romeo; Carpenter, Mark G; Sanderson, David J

2009-02-01

180

Selective weighting of cutaneous receptor feedback and associated balance impairments following short duration space flight.  

Science.gov (United States)

The present study investigated the perception of low frequency (3Hz) vibration on the foot sole and its relationship to standing balance following short duration space flight in nine astronauts. Both 3Hz vibration perception threshold (VPT) and standing balance measures increased on landing day compared to pre-flight. Contrary to our hypothesis, a positive linear relationship between these measures was not observed; however astronauts with the most sensitive skin (lowest 3Hz VPT) were found to have the largest sway on landing day. While the change in foot sole sensitivity does not appear to directly relate to standing balance control, an exploratory strategy may be employed by astronauts whose threshold to pressure information is lower. Understanding sensory adaptations and balance control has implications to improve balance control strategies following space flight and in sensory impaired populations on earth. PMID:25711797

Strzalkowski, Nicholas D J; Lowrey, Catherine R; Perry, Stephen D; Williams, David R; Wood, Scott J; Bent, Leah R

2015-04-10

181

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

OpenAIRE

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 w...

Sacchetti, A.; Degiorgi, L.; Giamarchi, T.; Ru, N.; Fisher, I. R.

2006-01-01

182

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)

Energetic 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

183

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.

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  

Energy Technology Data Exchange (ETDEWEB)

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. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22 000 (Algeria) and Laboratoire de Physique Quantique et de Modelisation Mathematique de la Matiere (LPQ3 M), Departement de Technologie, Universite de Mascara, 29 000 (Algeria)]. E-mail: khenata_rabah@yahoo.fr; Sahnoun, M. [Laboratoire de Physique Quantique et de Modelisation Mathematique de la Matiere (LPQ3 M), Departement de Technologie, Universite de Mascara, 29 000 (Algeria)]. E-mail: mohammed.sahnoun@unifr.ch; Baltache, H. [Laboratoire de Physique Quantique et de Modelisation Mathematique de la Matiere (LPQ3 M), Departement de Technologie, Universite de Mascara, 29 000 (Algeria); Rerat, M. [Laboratoire de Chimie Structurale UMR 5624, I.F.R rue Jules Ferry, Universite de Pau, 64 000 (France); Rached, D. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22 000 (Algeria); Driz, M. [Applied Materials Laboratory (AML), Electronics Department, University of Sidi-Bel-Abbes, 22 000 (Algeria); Bouhafs, B. [Modeling and simulation in Material Science Laboratory, Physics Department, University of Sidi-Bel-Abbes, 22 000 (Algeria)

2006-01-15

186

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-05-27

187

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

OpenAIRE

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 increases monotonically with increasing lattice parameter from 244(3) K for TmTe_3 to 416(3) K for SmTe_3. The heaviest members of the series, R = Dy, Ho, Er, Tm, are observed to have a second transition at a lower temperature, which ma...

Ru, N.; Condron, C. L.; Margulis, G. Y.; Shin, K. Y.; Laverock, J.; Dugdale, S. B.; Toney, M. F.; Fisher, I. R.

2006-01-01

188

Raman scattering of rare earth sesquioxide Ho{sub 2}O{sub 3}: A pressure and temperature dependent study  

Energy Technology Data Exchange (ETDEWEB)

Pressure and temperature dependent Raman scattering studies on Ho{sub 2}O{sub 3} have been carried out to investigate the structural transition and the anharmonic behavior of the phonons. Ho{sub 2}O{sub 3} 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 Ho{sub 2}O{sub 3} from 80?K to 440?K has been investigated. We find an anomalous line-width change with temperature. The mode Grüneisen parameter of bulk Ho{sub 2}O{sub 3} 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. [Pressure and Vacuum Standards, National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India)

2014-10-07

189

High-Pressure Deformation of Earth Materials: From Single-Crystal Rheology to the Modeling of Upper-Mantle Plasticity  

Science.gov (United States)

The past decade has been rich in technical and theoretical developments allowing new approaches in the investigation of the high-pressure plasticity of mantle materials. New high-pressure devices set at synchrotron X-ray facilities, such as the Deformation-DIA apparatus (D-DIA), allow quantifying materials rheology at pressure (P) in excess of 10 GPa. In the D-DIA, olivine and pyroxenes dislocation slip-systems properties have been studied individually within oriented single crystals deformed at mantle P and temperature (T). Together with estimates of lattice friction based on first-principle calculations (e.g., Durinck et al., Am. Mineral., 92, 1346-1357, 2007), these data can be incorporated into visco-plastic self-consistent (VPSC) schemes in order to assess peridotite microstructure evolution in relevant geodynamical contexts (e.g., Castelnau et al., Comptes Rendus Physique, 11, 304-315, 2010). VPSC modeling insures the continuity of both stress and strain throughout the deforming aggregate, taking into account the mean stress field as well as grain orientations on slip-system activities. Alternatively, individual slip-system properties can be integrated into analytical modeling of aggregate plasticity, which allows accounting for the effects of their individual sensitivities to parameters such as P, T and stress on the aggregate macroscopic properties (e.g., Raterron et al., PEPI, 200-201, 105-112, 2012). These multiscale approaches are powerful tools since they explain and account for effects never accounted before: variations with P in the aggregate-deformation sensitivity to pressure (the activation volume), effects of minor slip-system activities on rocks lattice preferred orientations (LPO), etc. It will be shown that combining state-of-the-art high-P deformation experiments with aggregate deformation computations allows addressing part of the complexity of upper-mantle plasticity.

Raterron, P. C.; Castelnau, O.; Chen, J.; Cordier, P.; Detrez, F.; Girard, J.; Merkel, S.

2012-12-01

190

Global-scale validation of model-based load deformation of the Earth's crust from continental watermass and atmospheric pressure variations using GPS  

Science.gov (United States)

Temporal mass variations in the continental hydrosphere and in the atmosphere lead to changes in the gravitational potential field that are associated with load-induced deformation of the Earth's crust. Therefore, models that compute continental water storage and atmospheric pressure can be validated by measured load deformation time series. In this study, water mass variations as computed by the WaterGAP Global Hydrology Model (WGHM) and surface pressure as provided by the reanalysis product of the National Centers for Environmental Prediction describe the hydrological and atmospheric pressure loading, respectively. GPS observations from 14 years at 208 stations world-wide were reprocessed to estimate admittance factors for the associated load deformation time series in order to determine how well the model-based deformation fits to real data. We found that such site-specific scaling factors can be identified separately for water mass and air pressure loading. Regarding water storage variation as computed by WGHM, weighted global mean admittances are 0.74 ± 0.09, 0.66 ± 0.10, 0.90 ± 0.06 for the north, east and vertical component, respectively. For the dominant vertical component, there is a rather good fit to the observed displacements, and, averaged over all sites, WGHM is found to slightly overestimate temporal variations of water storage. For Europe and North America, with a dense GPS network, site-specific admittances show a good spatial coherence. Regarding regional over- or underestimation of WGHM water storage variations, they agree well with GRACE gravity field data. Globally averaged admittance estimates of pre-computed atmospheric loading displacements provided by the Goddard Geodetic VLBI Group were determined to be 0.88 ± 0.04, 0.97 ± 0.08, 1.13 ± 0.01 for the north, east and vertical, respectively. Here, a relatively large discrepancy for the dominant vertical component indicates an underestimation of corresponding loading predictions.

Fritsche, Mathias; Döll, Petra; Dietrich, Reinhard

2012-09-01

191

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

International Nuclear Information System (INIS)

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

192

High-Pressure High-Temperature Equation of State of B1 Cobalt Oxide and Implications for Redox Relations in the Earth's Lower Mantle  

Science.gov (United States)

First row transition metals play important roles in the Earth's mantle by influencing minerals' phase stability, density and elastic properties, and helping to govern defect-mediated behavior including electrical and thermal conductivity, and rheology. Since transition metals are also somewhat siderophile, geochemical measurements of absolute and relative abundances of transition metals in mantle-derived rocks helps constrain the evolution of the core/mantle system, including initial segregation and continuing reactions. Interpreting the geochemical record in terms of partitioning of transition metals among oxide and metal phases requires measurements of thermoelastic properties of the oxide and metal phases at the high pressure and temperature conditions of the Earth's interior. The high pressure and temperature equation of state of rocksalt-structured cobalt oxide was measured up to 65 GPa and 2600 K using synchrotron X-ray diffraction in conjunction with the laser heated diamond anvil cell. We determine the best fit equation of state parameters to be V0=77.4 (fixed) Å3, K0T=190 (1) GPa, dK/dP =3.49 (4), ?0=1.54 (4), q=2.87 (15), and ?0=517.8 (fixed), using a Mie-Gruneisen-Debye parameterization. We use these values in conjunction with existing measurements of the cobalt metal equation of state to calculate chemical free energy differences between the cobalt oxide and cobalt metal phases as a function of pressure and temperature. A comparison of the Co/CoO with Ni/NiO system energetics (Campbell et al. 2009) predicts a crossing point at 55 GPa and 2000 K. This energy crossing point in energy can be mapped as a crossing point in electrochemical potential of the two metal ions, suggesting that the Ni becomes more siderophile than Co as pressure and temperature increases. This result is in good agreement with existing measurements of Ni and Co partition coefficients between mantle and core materials (O'Neill et al. 1998; Bouhifd and Jephcoat 2011).

Kavner, A.; Armentrout, M. M.

2012-12-01

193

Older Adults and Balance Problems  

Medline Plus

Full Text Available ... keep my balance and I was seeing double. Man: I woke up, I couldn't stand up. ... also experience nausea, diarrhea, faintness, or changes in heart rate or blood pressure. Woman: The most difficult ...

194

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

Science.gov (United States)

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

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

2012-12-01

195

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)

196

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

197

Phase Transitions and Equations of State of Alkaline Earth Fluorides CaF2 SrF2 and BaF2 to Mbar Pressures  

Energy Technology Data Exchange (ETDEWEB)

Phase transitions and equations of state of the alkaline earth fluorides CaF{sub 2}, SrF{sub 2}, and BaF{sub 2} were examined by static compression to pressures as high as 146 GPa. Angle-dispersive x-ray diffraction experiments were performed on polycrystalline samples in the laser-heated diamond-anvil cell. We confirmed that at pressures less than 10 GPa all three materials undergo a phase transition from the cubic (Fm3{sup -}m) fluorite structure to the orthorhombic (Pnam) cotunnite-type structure. This work has characterized an additional phase transition in CaF{sub 2} and SrF{sub 2}: these materials were observed to transform to a hexagonal (P6{sub 3}/mmc) Ni{sub 2}In-type structure between 63-79 GPa and 28-29 GPa, respectively, upon laser heating. For SrF{sub 2}, the Ni{sub 2}In-type phase was confirmed by Rietveld refinement. Volumes were determined as a function of pressure for all high-pressure phases and fit to the third-order Birch-Murnaghan equation of state. For CaF{sub 2} and SrF{sub 2}, the fluorite-cotunnite transition results in a volume decrease of 8-10%, while the bulk modulus of the cotunnite-type phase is the same or less than that of the fluorite phase within uncertainty. For all three fluorides, the volume reduction associated with the further transition to the Ni{sub 2}In-type phase is {approx}5%. The percentage increase in the bulk modulus ({Delta}K) across the transition is greater when the cation is smaller. While for BaF{sub 2}, {Delta}K is 10-30%, {Delta}K values for SrF{sub 2} and CaF{sub 2} are 45-65% and 20-40%. Although shock data for CaF{sub 2} have been interpreted to show a transition to a highly incompressible phase above 100 GPa, this is not consistent with our static equation of state data.

S Dorfman; F Jiang; Z Mao; A Kubo; Y Meng; V Prakapenda; T Duffy

2011-12-31

198

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

Energy Technology Data Exchange (ETDEWEB)

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

Buelow, Nicholas Lee

2005-08-01

199

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

CERN Document Server

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

Frueh, Carolin; Kelecy, Thomas

2013-01-01

200

CaCO3-III and CaCO3-VI, high-pressure polymorphs of calcite: Possible host structures for carbon in the Earth's mantle  

Science.gov (United States)

Calcite, CaCO3, undergoes several high pressure phase transitions. We report here the crystal structure determination of the CaCO3-III and CaCO3-VI high-pressure polymorphs obtained by single-crystal synchrotron X-ray diffraction. This new technical development at synchrotron beamlines currently affords the possibility of collecting single-crystal data suitable for structure determination in-situ at non-ambient conditions, even after multiphase transitions. CaCO3-III, observed in the pressure range 2.5-15 GPa, is triclinic, and it presents two closely related structural modifications, one, CaCO3-III, with 50 atoms in the unit cell [a=6.281(1) Å, b=7.507(2) Å, c=12.516(3) Å, ?=93.76(2)°, ?=98.95(2)°, ?=106.49(2)°, V=555.26(20) Å3 at 2.8 GPa], the second, CaCO3-IIIb, with 20 atoms [a=6.144(3) Å, b=6.3715(14) Å, c=6.3759(15) Å, ?= 93.84(2)°, ?=107.34(3)°, ?=107.16(3)°, V=224.33(13) Å3 at 3.1 GPa]. Different pressure-time experimental paths can stabilise one or the other polymorph. Both structures are characterised by the presence of non-coplanar CO3 groups. The densities of CaCO3-III (2.99 g/cm3 at 2.8 GPa) and CaCO3-IIIb (2.96 g/cm3 at 3.1 GPa) are lower than aragonite, in agreement with the currently accepted view of aragonite as the thermodynamically stable Ca-carbonate phase at these pressures. The presence of different cation sites, with variable volume and coordination number (7-9), suggests however that these structures have the potential to accommodate cations with different sizes without introducing major structural strain. Indeed, this structure can be adopted by natural Ca-rich carbonates, which often exhibit compositions deviating from pure calcite. Mg-calcites are found both in nature (Frezzotti et al., 2011) and in experimental syntheses at conditions corresponding to deep subduction environments (Poli et al., 2009). At these conditions, the low pressure rhombohedral calcite structure is most unlikely to be stable, and, at the same time, Mg and Fe solubility in aragonite is hindered energetically in the 9-fold coordination site. Above 15 GPa, and up to the maximum pressure investigated (40 GPa), we observe the high-pressure polymorph CaCO3-VI, triclinic [a=3.3187(12) Å, b=4.8828(14) Å, c=5.5904(14) Å, ?=103.30(2)°, ?=94.73(2)°, ?=89.21(2)°, V=87.86(20) Å3 at 30.4 GPa] with 10 atoms in the unit cell. It is characterised by coplanar CO3 groups but the structure is no longer layered, as in the lower pressure polymorphs. The density of the CaCO3-VI structure (3.78 g/cm3 at 30.4 GPa) is higher than aragonite. For this reason it could be supposed that a region may exist where this polymorph replaces aragonite in the Earth's intermediate mantle. The lower coordination number for the Ca site [7+2] instead of [9] in aragonite suggests that this structure could be easily adopted by an extended solid-solution range from calcite towards the dolomite [CaMg(CO3)2]-ankerite [CaFe(CO3)2] compositional join. The transitions from calcite to CaCO3-III, CaCO3-IIIb and CaCO3-VI are perfectly reversible and after pressure release we always observe the calcite structure, with the sample recovered as a single-crystal. Indeed, it is highly unlikely that these structures can be observed in samples recovered from high-pressure environments.

Merlini, M.; Hanfland, M.; Crichton, W. A.

2012-06-01

201

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

Scientific Electronic Library Online (English)

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

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

2005-06-01

202

Keeping Your Balance  

Science.gov (United States)

... are here Home » Keeping Your Balance Keeping Your Balance Balance is very important for people with osteoporosis. ... ear and significantly improve your balance. Testing Your Balance If you want to test how your eyes ...

203

Balancing Eggs  

Science.gov (United States)

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

Mills, Allan

2014-01-01

204

Microstructure and property evaluation of high-pressure die-cast Mg–La–rare earth (Nd, Y or Gd) alloys  

International Nuclear Information System (INIS)

Highlights: • Different rare earth elements have remarkably different effects on Mg castability. • For the addition of each RE element, the alloy castability follows a unique pattern. • The effects of RE elements on the castability can be modelled. - Abstract: Microstructure, castability and tensile properties were investigated in high-pressure die-cast Mg–La–Nd, Mg–La–Y and Mg–La–Gd alloy series, with a constant La concentration at approximately 2.5 wt.% and the concentrations of Nd, Y or Gd were varied. All three alloy series had a dendritic microstructure with a Mg–La-rich eutectic with increasing Nd, Y or Gd content and containing a Mg12RE intermetallic phase. The morphology of the eutectic at ternary alloying additions of equal to or less than 1.0 wt.% was lamellar but became increasingly divorced at higher ternary concentrations. This was however more obvious in Mg–La–Y and Mg–La–Gd than Mg–La–Nd alloys. The hot tearing susceptibility in all three alloy series increased markedly with even micro-alloying additions of Nd, Y or Gd, and began to decrease again in alloys with more than 0.5 wt.% Y or 1.0 wt.% Gd, but did not decrease significantly for Mg–La–Nd. A model using the temperature–fraction solid curves as input parameters was used to estimate hot tearing susceptibility for Mg–La–Nd alloys. Tensile testing at room temperature showed that Mg–La–Nd alloy series had higher 0.2% proof stress and lower elongation to failure than either the Mg–La–Y or the Mg–La–Gd alloy series for Nd concentrations greater than 1 wt.% due to a greater effectiveness of grain boundary reinforcement

205

Earth meandering  

Science.gov (United States)

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

Asadiyan, H.; Zamani, A.

2009-04-01

206

Lesson "Balance in Nature  

Science.gov (United States)

Lesson "Balance in Nature" This simulation game-lesson (Balance in Nature) gives an opportunity for the students to show creativity, work independently, and to create models and ideas. It creates future-oriented thought connected to their experience, allowing them to propose solutions for global problems and personal responsibility for their activities. The class is divided in two teams. Each team chooses questions. 1. Question: Pollution in the environment. 2. Question: Care for nature and climate. The teams work on the chosen tasks. They make drafts, notes and formulate their solutions on small pieces of paper, explaining the impact on nature and society. They express their points of view using many different opinions. This generates alternative thoughts and results in creative solutions. With the new knowledge and positive behaviour defined, everybody realizes that they can do something positive towards nature and climate problems and the importance of individuals for solving global problems is evident. Our main goal is to recover the ecological balance, and everybody explains his or her own well-grounded opinions. In this work process the students obtain knowledge, skills and more responsible behaviour. This process, based on his or her own experience, dialogue and teamwork, helps the participant's self-development. Making the model "human? nature" expresses how human activities impact the natural Earth and how these impacts in turn affect society. Taking personal responsibility, we can reduce global warming and help the Earth. By helping nature we help ourselves. Teacher: Veselina Boycheva-Chapanova " Saint Patriarch Evtimii" Scholl Str. "Ivan Vazov"-19 Plovdiv Bulgaria

Chapanova, V.

2012-04-01

207

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

208

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

Science.gov (United States)

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

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

2011-01-01

209

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.

210

New high pressure rare earth tantalates RE{sub x}Ta{sub 2}O{sub 5+1.5x} (RE=La, Eu, Yb)  

Energy Technology Data Exchange (ETDEWEB)

Rare earth tantalates La{sub 0.075}Ta{sub 2}O{sub 5.113}, Eu{sub 0.089}Ta{sub 2}O{sub 5.134} and Yb{sub 0.051}Ta{sub 2}O{sub 5.077} 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–Ta{sub 2}O{sub 5} [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: La{sub 0.075}Ta{sub 2}O{sub 5.113}, a=10.5099(2), b=7.2679(1), c=6.9765(1) Å, V=532.90(1) Å{sup 3}, Z=6, space group Ibam; Eu{sub 0.089}Ta{sub 2}O{sub 5.134}, a=10.4182(3), b=7.2685(1), c=6.9832(1) Å, V=528.80(2) Å{sup 3}, Z=6, space group Ibam; Yb{sub 0.051}Ta{sub 2}O{sub 5.077}, a=10.4557(2), b=7.3853(1), c=6.8923(1) Å, V=532.21(1) Å{sup 3}, 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{sup +3} compress the unit cell so that its volume becomes less than that of F–Ta{sub 2}O{sub 5}. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer. - Graphical abstract: The structure of RE{sub x}Ta{sub 2}O{sub 5+1.5x} and its HRTEM image (“A” arrows show empty channel, “B” arrows show filled channel). - Highlights: • We synthesized new tantalates of RE under high pressure high temperature conditions. • RE atoms replace water molecules in the channels of the structure. • Aqueous as well as anhydrous tantalates were obtained. • Highly charged cations RE{sup +3} compress the unit cell decreasing RE–O distances.

Zibrov, Igor P., E-mail: zibrov@mail.ru [Institute for High Pressure Physics, Russian Academy of Sciences, Kaluzhskoe Highway 14, Troitsk, Moscow 142190 (Russian Federation); Filonenko, Vladimir P., E-mail: filv@hppi.troitsk.ru [Institute for High Pressure Physics, Russian Academy of Sciences, Kaluzhskoe Highway 14, Troitsk, Moscow 142190 (Russian Federation); Zakharov, Nikolai D., E-mail: zakharov@mpi-halle.mpg.de [Max Planck Institute for Microstructure Physics, Weinberg 2, D-06120 Halle/Saale (Germany); Werner, Peter, E-mail: werner@mpi-halle.mpg.de [Max Planck Institute for Microstructure Physics, Weinberg 2, D-06120 Halle/Saale (Germany); Drobot, Dmitrii V., E-mail: dvdrobot@mail.ru [Lomonosov Moscow University of Fine Chemical Technology, Prospect Vernadskogo 86, Moscow 119571 (Russian Federation); Nikishina, Elena E.; Lebedeva, Elena N., E-mail: helena_nick@mail.ru [Lomonosov Moscow University of Fine Chemical Technology, Prospect Vernadskogo 86, Moscow 119571 (Russian Federation)

2013-07-15

211

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

International Nuclear Information System (INIS)

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

212

Human Balance System  

Science.gov (United States)

... VEDA” to receive a 15% discount. The Human Balance System Good balance is often taken for granted. Most people don’ ... and difficulty with concentration and memory. What is balance? Balance is the ability to maintain the body’s ...

213

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 ...

214

Balance (or Vestibular) Rehabilitation  

Science.gov (United States)

Balance (or Vestibular) Rehabilitation Audiologic (hearing), balance, and medical diagnostic tests help indicate whether you are a candidate for vestibular (balance) rehabilitation. Vestibular rehabilitation is an individualized balance retraining ...

215

Social Balance Theory  

OpenAIRE

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

Khanafiah, Deni; Situngkir, Hokky

2004-01-01

216

Modern rotor balancing - Emerging technologies  

Science.gov (United States)

Modern balancing methods for flexible and rigid rotors are explored. Rigid rotor balancing is performed at several hundred rpm, well below the first bending mode of the shaft. High speed balancing is necessary when the nominal rotational speed is higher than the first bending mode. Both methods introduce weights which will produce rotor responses at given speeds that will be exactly out of phase with the responses of an unbalanced rotor. Modal balancing seeks to add weights which will leave other rotor modes unaffected. Also, influence coefficients can be determined by trial and error addition of weights and recording of their effects on vibration at speeds of interest. The latter method is useful for balancing rotors at other than critical speeds and for performing unified balancing beginning with the first critical speed. Finally, low-speed flexible balancing permits low-speed tests and adjustments of rotor assemblies which will not be accessible when operating in their high-speed functional configuration. The method was developed for the high pressure liquid oxygen turbopumps for the Shuttle.

Zorzi, E. S.; Von Pragenau, G. L.

1985-01-01

217

ATLAS 1: Encountering planet Earth  

Science.gov (United States)

Several NASA science programs examine the dynamic balance of sunlight, atmosphere, water, land, and life that governs Earth's environment. Among these is a series of Space Shuttle-Spacelab missions, named the Atmospheric Laboratory for Applications and Science (ATLAS). During the ATLAS missions, international teams of scientists representing many disciplines combine their expertise to seek answers to complex questions about the atmospheric and solar conditions that sustain life on Earth. The ATLAS program specifically investigates how Earth's middle atmosphere and upper atmospheres and climate are affected by both the Sun and by products of industrial and agricultural activities on Earth.

Shea, Charlotte; McMahan, Tracy; Accardi, Denise; Tygielski, Michele; Mikatarian, Jeff; Wiginton, Margaret

218

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

International Nuclear Information System (INIS)

Total vapor-phase densities of Dy in equilibrium with a DyI3/InI condensate and Tm in equilibrium with a TmI3/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.

219

Optical absorption and determination of band offset in strain-balanced GaInP/InAsP multiple quantum wells grown by low-pressure metalorganic vapour phase epitaxy  

Science.gov (United States)

We report on optical absorption of the interband transitions in zero-net strained 0268-1242/12/5/006/img12 multiple quantum wells (MQW) grown by low-pressure metalorganic vapour phase epitaxy (LP-MOVPE), using tertiarybutylarsine as a group V source. Sharp interfaces are obtained using a growth interruption procedure. Analysis of this procedure with different interruption times leads to the same optimal times as those obtained for InP/InAsP superlattices grown in the same reactor. We have achieved the growth of modulation-free strain-balanced heterostructures, as indicated by cross-sectional transmission electron microscopy. High-resolution x-ray diffraction and optical absorption analysis demonstrate the high crystallographic and optical quality of these structures. The absorption spectrum of an x = 0.06, y = 0.14 sample was accurately fitted using the Bastard/Marzin model, and a strained conduction band offset of 0268-1242/12/5/006/img13 was deduced. This corresponds to about 0268-1242/12/5/006/img14 of the total strained bandgap difference.

Ababou, Y.; Desjardins, P.; Chennouf, A.; Masut, R. A.; Yelon, A.; Beaudoin, M.; Bensaada, A.; Leonelli, R.; L'Espérance, G.

1997-05-01

220

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

221

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

222

Earth System: Ice and Global Warming  

Science.gov (United States)

This video segment adapted from NASA's Goddard Space Flight Center explains ice's role in the Earth system, highlighting the delicate balance that could be upset with a continued rise in temperature due to climate change.

WGBH Educational Foundation

2005-12-17

223

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 ...

224

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 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.

225

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  

OpenAIRE

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

226

Balancing risks.  

Science.gov (United States)

Regulatory policies designed to reduce the health risk of environmental and/or synthetic chemicals generally aim for zero or negligible levels. Foods, on the other hand, especially those with a long history in the human diet, have been treated as essentially safe, even though they too contain various chemicals including nutrients. The recent debate on the presence in food of acrylamide, a possible human carcinogen, is likely to shake up the traditional paradigm held by regulatory agencies on chemical health risks. The current stance on the safety of acrylamide in food seems to be an extension of the traditional approach to assessment of environmental and/or synthetic chemicals. However, even foods which have long been a part of the human diet contain components that do not necessarily meet the safety margins applied to environmental and/or synthetic chemicals. In the future, a greater understanding of the effect of these agents on biological systems as well as the development of analytical methods for testing will result in many questions being raised concerning chemicals in foods, such as acrylamide which is under scrutiny today. Regulatory policies currently employ various standards for controlling chemical risk. These standards are dependent upon the labeling of the chemical in question, e.g., whether carcinogenic or non-carcinogenic, synthetic or natural, or whether a food or industrial chemical. Regardless of labeling, all chemicals to which we are exposed should be evaluated on an equal footing. Then, according to the level of the identified health risk, regulations could or could not be applied based on local circumstances, e.g., public acceptance, voluntary risk vs. involuntary risk, etc. In order to create a standardized system for chemical risk assessment, the introduction of uniform measures is essential. Loss of life expectancy (LLE) is one possible measure to assess chemical health risk. When LLE has been used, animal toxicity data have indicated that an ad libitum diet intake has considerably more impact on health risk than the acrylamide concentration of the ingested food. Reassessing the health effects of chemicals with a system of uniform measures could reveal many risks that need to be preferentially addressed above and beyond keeping minor toxicants to zero or negligible levels. Recognition of such risks may result in changes that conflict with existing regulations. In any case, whether consciously or unconsciously, people have always been exposed to a certain degree of chemical risk in their daily life. Based on the premise that the public can accept some degree of chemical risk in balance with other risks in their lives, regulatory bodies should be able to take a flexible and effective approach. In order to efficiently and comprehensively maximize the protection of our health against potential harm from chemicals using limited public resources, it is now time for regulatory agencies to restructure their policy frameworks across categories for controlling chemical health risks. PMID:16843577

Kasamatsu, Toshio; Kohda, Kohfuku

2006-10-01

227

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

228

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...

229

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

230

Persistence of oceans on Earth-like planets  

Science.gov (United States)

The habitable zone is an orbital region around a star in which an Earth-like planet can maintain liquid water on its surface given a variety of atmospheric compositions. However, the abundance of water on the Earth's surface is not controlled by the atmosphere, but rather by the deep water/silicate cycle. On the Earth, volcanic outgassing of water from the mantle is balanced by loss of water to the mantle through subduction of water-rich oceanic seafloor. Much of this water is released immediately back to the surface through shallow, water-induced volcanism. However, a small but significant fraction of the water can be transported to deeper levels of the mantle. Mantle convection has therefore played an important role in controlling the size of Earth's surface oceans over the planet's lifetime.The deep water cycle of Earth has been studied with parameterized convection models incorporating a water-dependent viscosity. The abundance of water in the mantle, which lowers the convective viscosity, evolves along with the mantle temperature. Here we present results from a parameterized convection model extended to high pressures to study the deep water cycles of super-Earths. Assuming compositions similar to the Earth, our models indicate that ocean formation will be delayed on 5 MEarth planets by ~1 Gyr after planet formation. Although ocean mass on these planets increases with time, the oceans remain much shallower than for smaller planets, consistent with previous studies. Intermediate mass planets (2-4 MEarth) have immediate, but gradual outgassing and persistent oceans. Small terrestrial planets (? 1 MEarth) have rapid initial outgassing, but will gradually lose a significant fraction of their surface oceans due to mantle sequestration over their lifetimes.

Schaefer, Laura; Sasselov, Dimitar D.

2015-01-01

231

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

232

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

233

Earth Calendar  

Science.gov (United States)

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

Jeffrey Barker

234

The Balancing Act  

Science.gov (United States)

Students visualize and interact with concepts already learned, specifically algebraic equations and solving for unknown variables. They construct a balancing seesaw system (LEGO® Balance Scale) made from LEGO MINDSTORMS® parts and digital components to mimic a balancing scale. They are given example algebraic equation problems to analyze, configure onto the balance scale, and evaluate by manipulating LEGO pieces and gram masses that represent terms of an equation such as unknown variables, coefficients and integers. Digital light sensors, built into the LEGO Balance Scale, detect any balance or imbalances displayed on the balancing scale. The LEGO Balance Scale interactively issues a digital indication of balance or imbalance within the system. If unbalanced, students continue using the LEGO Balance Scale until they are confident in their understanding of solving algebraic equations. The goal is for students to become confident in solving algebraic equations by fundamentally understanding the basics of algebra and real-world algebraic applications.

AMPS GK-12 Program,

235

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

Science.gov (United States)

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

Gürsoy, M.; Takeda, M.; Albert, B.

2015-01-01

236

THE COSMIC-RAY INTENSITY NEAR THE ARCHEAN EARTH  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-20

237

Celebrate Earth  

Science.gov (United States)

The Earth is truly something to celebrate! Click on the links below and have some fun! Click on the link to send you to a fun website created just for kids like you! Now go celebrate the earth! Kids for Saving Earth Enjoy these other activities as well! Go recycling! A is for Air Discover what all of the letters of the alphabet can stand for! video Get on ...

Mrs. Rokes

2009-04-23

238

Earth Viewer  

Science.gov (United States)

Earth Viewer was written primarily for elementary school students, and shows the daytime and nighttime portions of the Earth for any day of the year. Two views of the Earth are possible: a globe shows the planet as it would appear from space, and a map shows a flat view of the entire surface. The image can be animated or still, and set to any desired latitude and longitude.

Paul Carlisle

239

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

240

Earth Force  

Science.gov (United States)

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

241

Rare earths  

International Nuclear Information System (INIS)

Rare earth elements are commonly extracted from the minerals monazite, bastnaesite, and xenotine. New uses for these elements are constantly developing; they have found applications in glass polishing, television tube phosphors, high-strength low-alloy steels, magnets, catalysts, refractory ceramics, and hydrogen sponge alloys. In Canada, rare earths have been produced as byproducts of the uranium mining industry, but there was no production of rare earths in 1978 or 1979. The world sources of and markets for the rare earth elements are discussed

242

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

International Nuclear Information System (INIS)

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

243

Monkey Math Balance  

Science.gov (United States)

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

Vaisaga Project

244

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

245

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

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

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.

254

Isotope composition and volume of Earth´s early oceans  

DEFF Research Database (Denmark)

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

Pope, Emily Catherine; Bird, Dennis K.

2012-01-01

255

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 ...

256

Earth watch  

Energy Technology Data Exchange (ETDEWEB)

Over 80 LANDSAT images are presented in a spacious format in Earth Watch, an associated volume to Man on Earth by the same author, which contains only 5 plates concerned with petroleum-related activities. Each plate is accompanied by an explanatory diagram and map, and a short textual description in which the salient features of each image are interpreted, and a geographical and historical summary provided. Earth Watch contains an informative introduction to the techniques of image transmission, selection and false-color reproduction.

Sheffield, C.

1986-01-01

257

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

258

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

259

Earth Systems  

Science.gov (United States)

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

Houghton Mifflin Science

260

Earth's Surface  

Science.gov (United States)

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

Houghton Mifflin Science

261

Rare earths  

International Nuclear Information System (INIS)

There has been no Canadian production of the rare earth oxides since 1977. World production in 1978, the last year for which figures are available, is estimated to have been about 41000 tonnes, mostly from Australia and the United States. The United States Bureau of Mines estimates that world reserves contain about 7 million tonnes of rare earth oxides and 35 million tonnes of yttrium. The largest yttrium reserves are in India, while China is believed to have the world's largest reserves of rare earth oxides. World consumption of rare aarths increased slightly in 1980, but is still only a small fraction of known reserves. Rare earths are used mainly in high-strength magnets, automobile exhaust systems, fluorescent tube and television screen phosphors, metallurgical applications, petroleum cracking catalysts, and glass polishing

262

Earth Day  

Science.gov (United States)

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

263

Rare earths  

International Nuclear Information System (INIS)

The participants in the conference heard 22 papers of which 14 are inputted in INIS. They discussed the technology of the separation of rare earth elements, extraction separation and refining of lanthanides, thorium sorption from bastnaesite eluates using ion exchangers, various methods of separating Eu, radioanalytical methods and the use of plasma emission analysis in determining rare earth elements. (E.J.). 4 figs., 10 tabs., 18 refs

264

Regimes of validity for balanced models  

Science.gov (United States)

Scaling analyses are presented which delineate the atmospheric and oceanic regimes of validity for the family of balanced models described in Gent and McWilliams (1983a). The analyses follow and extend the classical work of Charney (1948) and others. The analyses use three non-dimensional parameters which represent the flow scale relative to the Earth's radius, the dominance of turbulent or wave-like processes, and the dominant component of the potential vorticity. For each regime, the models that are accurate both at leading order and through at least one higher order of accuracy in the appropriate small parameter are then identified. In particular, it is found that members of the balanced family are the appropriate models of higher-order accuracy over a broad range of parameter regimes. Examples are also given of particular atmospheric and oceanic phenomena which are in the regimes of validity for the different balanced models.

Gent, Peter R.; McWilliams, James C.

1983-07-01

265

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

266

A safety analysis of warhead balancing  

Energy Technology Data Exchange (ETDEWEB)

Reentry vehicles (RVs) carrying warheads from ballistic missiles must be carefully balanced with the warhead in situ to prevent wobble as the RVs enter the earth`s atmosphere to prevent inaccuracy or loss of the warhead. This balancing is performed on a dynamic balancing machine that rotates the RV at significant angular velocities. Seizure of the spindle shaft of the machine could result in rapid deceleration of the rotating assembly, which could over-stress and shear bolts or other structures that attach the RV to the balancing machine. This could result in undesired motions of the RV and impact of the RV on equipment or structures in the work area. This potential safety problem has long been recognized in a general way, but no systematic investigation of the possible accident sequences had been performed. The purpose of this paper is to describe an integrated set of systems analysis techniques that worked well in developing a set of accident sequences that describe the motions of the RV following a spindle-shaft seizure event.

Bott, T.F.

1998-12-01

267

Hydrogen Escape from early Earth and Mars  

Science.gov (United States)

A controversy regarding hydrodynamic escape rates arose when Tian et al. (2005) published transonic escape rates for an atmosphere composed of pure H2. Tian et al. concluded that the hydrogen escape rate from early Earth would have been a factor of 20 or more slower than the diffusion limit, even if the solar EUV (extreme ultraviolet) flux was enhanced by a factor of 5 relative to today. This conclusion was challenged by Catling (2006), who pointed out that solar EUV fluxes could have been much higher than this so that plenty of energy should have been available to power escape. This controversy has remained unresolved to date. Hydrogen escape from early Mars is also of interest. As discussed in this session in a complementary paper by Ramirez et al., collision-induced absorption by molecular hydrogen could have helped to warm early Mars, perhaps explaining the formation of valleys and valley networks. Ramirez et al. have shown that a mixture of 90% CO2 and 10% H2 is capable raising early Mars' surface temperature above the freezing point of water, for surface pressures exceeding ~3 bar. However, we need to understand whether H2 mixing ratios of 10% are physically plausible. The H2 partial pressure in Mars' early atmosphere would have been determined by the balance between volcanic outgassing and escape to space. The 10% mixing ratio is high compared to the value of ~10-3 typically assumed for early Earth. But Mars' early atmosphere may have been more reduced than Earth's (Wadwha, 2001); if the hydrogen escape rate on Mars was also slower than on Earth, then additional increases in atmospheric hydrogen concentration are possible. To answer these questions about the early atmospheres of Earth and Mars, we have modified an existing model of hydrodynamic escape, developed by F. Tian, J. Kasting, and others, to converge for atmospheres with a wide range of hydrogen mixing ratios. The model finds subsonic solutions to the hydrodynamic equations; these can be shown to have nearly the same escape flux as the transonic solution (the fastest outflow possible), provided that the maximum Mach number of the flow is close to unity. We achieve high Mach numbers by varying the velocity uinfinity, at the top of the model. By doing so, we simulate nonthermal, as well as thermal, escape processes. We assert without proof that there is a limit beyond which one cannot further increase uinfinity without producing unphysical results; that limit is the maximum, EUV-limited hydrodynamic escape rate. At low hydrogen mixing ratios, the escape rate follows the diffusion limit, as expected. At higher hydrogen mixing ratios, though, the escape rate flattens out, and even decreases. A similar effect is found when we apply our model to early Mars. Thus, there may have been an optimum time in Mars' early history for building up a dense, warm CO2-H2 atmosphere, after the solar EUV flux had dropped somewhat, but while the volcanic outgassing rate and magnetic field were still strong. If so, this CO2-H2 greenhouse mechanism may help to explain how the valleys formed on early Mars. References Catling DC. 2006. Comment on "A hydrogen-rich early Earth atmosphere". Science 311: 38a-b Tian F, Toon OB, Pavlov AA, De Sterck H. 2005. A hydrogen rich early Earth atmosphere. Science 308: 1014-7 Wadhwa M. 2001. Redox state of Mars' upper mantle and crust from Eu anomalies in Shergottite pyroxenes. Science 291: 1527-30

Zugger, M. E.; Ramirez, R. M.; Kasting, J. F.

2012-12-01

268

The quiet evening auroral arc and the structure of the growth phase near-Earth plasma sheet  

Science.gov (United States)

The plasma pressure and current configuration of the near-Earth plasma sheet that creates and sustains the quiet evening auroral arc during the growth phase of magnetospheric substorms is investigated. We propose that the quiet evening arc (QEA) connects to the thin near-Earth current sheet, which forms during the development of the growth phase enhancement of convection. The current sheet's large polarization electric fields are shielded from the ionosphere by an Inverted-V parallel potential drop, thereby producing the electron precipitation responsible for the arc's luminosity. The QEA is located in the plasma sheet region of maximal radial pressure gradient and, in the east-west direction, follows the vanishing of the approximately dawn-dusk-directed gradient or fold in the plasma pressure. In the evening sector, the boundary between the Region1 and Region 2 current systems occurs where the pressure maximizes (approximately radial gradient of the pressure vanishes) and where the approximately radial gradient of the magnetic flux tube volume also vanishes in an inflection region. The proposed intricate balance of plasma sheet pressure and currents may well be very sensitive to disruption by the arrival of equatorward traveling auroral streamers and their associated earthward traveling dipolarization fronts.

Coroniti, F. V.; Pritchett, P. L.

2014-03-01

269

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

270

Weather Stations: Temperature and Pressure  

Science.gov (United States)

In this activity, learners discover the relationship between temperature and pressure in the lower atmospheres of Jupiter and Earth. Learners chart the increasing temperature as they add pressure to a 2-L soda bottle with a Fizz-Keeper Pump. This activity is one station that can be combined with other stations for an hour and half lesson on weather patterns on Jupiter and Earth.

Lunar and Planetary Institute

2011-01-01

271

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,

272

Synthetic Investigations in Rare-Earth Borates, Gallates, Oxides, and Gallium Oxonitrides at Extreme Conditions  

OpenAIRE

The present phD thesis concerns synthetic investigations under extreme conditions of high-temperature and high-pressure. The high-temperature / high-pressure experiments, performed using a multianvil high-pressure device, led to the first single crystals of various rare-earth gallates, rare-earth borates, rare-earth oxides and gallium oxonitrides.

Hering, Stefanie Alexandra

2010-01-01

273

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.

Illuminations National Council of Teachers of Mathematics

2009-03-04

274

Balance and Stroke Risk  

Medline Plus

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

275

The Technology Balance Beam  

Science.gov (United States)

"The Technology Balance Beam" is designed to question the role of technology within school districts. This case study chronicles a typical school district in relation to the school district's implementation of technology beginning in the 1995-1996 school year. The fundamental question that this scenario raises is, What is the balance between…

Coulson, Eddie K.

2006-01-01

276

Rock Cycle: Earth's Autobiography  

Science.gov (United States)

This Science Object is the fourth of four Science Objects in the Rocks SciPack. It investigates how geologists have used rocks to help determine the approximate age of the Earth and provide a timeline of how the Earth's surface and environments have changed over time. Scientists have tools to estimate the ages of rock and the overall time scale of the rock cycle. Some processes happen quickly and some happen slowly, but the oldest rocks indicate that the rock cycle has been recycling Earth's material continuously for roughly 4 billion years. The same processes have been at work throughout Earth's history, and therefore scientists can use the present to interpret the past. Observations of rock (textures, minerals, and fossils found within it) provides evidence of the environment and processes through which it formed, including the pressures, temperatures, and forces that created it.Learning Outcomes:? State the amount of time over which the rock cycle has been in operation (4 billion years rather than 40 million or 400 million).? Recognize that the processes at work in the present are the same as those at work in the distant past.

National Science Teachers Association (NSTA)

2006-11-01

277

Pressure vessel for a nuclear power station  

International Nuclear Information System (INIS)

This proposal concerns the temperature balance inside a pressure vessel of reinforced concrete which is provided with a certain number of caverns covered with a metallic layer. In the center is a gas cooled high temperature nuclear reactor. Inside the pressure vessel there is a closed loop system where a cooling medium transports heat from places with high temperature to places with lower temperature. This ensures the temperature balance for avoiding thermal stresses in the pressure vessel walls. (UWI)

278

Savage Earth  

Science.gov (United States)

The Savage Earth website is the on-line companion to the PBS television series of the same name. This site tells the stories of several great natural disasters, particularly the eruption of Mt. Vesuvius in 79 A.D. that destroyed Pompeii and the 1994 earthquake in Kobe, Japan. It contains articles on the earth's crust and plate tectonics, earthquakes, volcanoes, and tsunamis. Each article features photographs, animated drawings, and video clips. For example, the earthquakes article includes animations of types of faults and three different kinds of seismic waves. There is also a question and answer section and links to related sites about geology and natural hazards.

2002-04-24

279

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

280

Geoelectromagnetic investigation of the earth’s crust and mantle  

CERN Document Server

Electrical conductivity is a parameter which characterizes composition and physical state of the Earth's interior. Studies of the state equations of solids at high temperature and pressure indicate that there is a close relation be­ tween the electrical conductivity of rocks and temperature. Therefore, measurements of deep conductivity can provide knowledge of the present state and temperature of the Earth's crust and upper mantle matter. Infor­ mation about the temperature of the Earth's interior in the remote past is derived from heat flow data. Experimental investigation of water-containing rocks has revealed a pronounced increase of electrical conductivity in the temperature range D from 500 to 700 DC which may be attributed to the beginning of fractional melting. Hence, anomalies of electrical conductivity may be helpful in identitying zones of melting and dehydration. The studies of these zones are perspective in the scientific research of the mobile areas of the Earth's crust and upper mantle where t...

Rokityansky, Igor I

1982-01-01

281

The Effects of Virtual Reality-based Balance Training on Balance of the Elderly.  

Science.gov (United States)

[Purpose] The objective of this study was to determine the effects of virtual reality-based balance training on balance of the elderly. [Methods] The subjects were 32 healthy elderly people aged between 65 and 80, who were divided into a VR (virtual reality) training group (n=17) and a control group (n=15). The VR training group engaged in a 30-minute exercise session using Wii Fit three times a week for eight weeks, while the control group received no intervention. The balance of the two groups was measured before and after the intervention. [Results] According to the Romberg Test conducted to examine the effects of the training on balance, both the area covered by the body's center of pressure movement, and movement distances per unit area of the body's center of pressure envelope significantly decreased in the VR training group. Moreover, the two groups showed significant differences in balance. [Conclusion] Virtual reality training is effective at improving the balance of the healthy elderly. Thus, virtual reality training can be proposed as a form of fall prevention exercise for the elderly. PMID:24764645

Cho, Gyeong Hee; Hwangbo, Gak; Shin, Hyung Soo

2014-04-01

282

Antarctic mass balance changes from GRACE  

Science.gov (United States)

The Antarctic ice sheet contains ~30 million km3 of ice and constitutes a significant component of the global water balance with enough freshwater to raise global sea level by ~60 m. Altimetry measurements and climate models suggest variable behaviour across the Antarctic ice sheet, with thickening occurring in a vast area of East Antarctica and substantial thinning in West Antarctica caused by increased temperature gradients in the surrounding ocean. However, the rate at which the polar ice cap is melting is still poorly constrained. To calculate the mass loss of an ice sheet it is necessary to separate present day mass balance changes from glacial isostatic adjustment (GIA), the response of the Earth's crust to mass loss, wherefore it is essential to undertake sufficient geological and geomorphological sampling. As there is only a limited possibility for this in Antarctica, all models (i.e. geological, hydrological as well as atmospheric) are very poorly constrained. Therefore, space-geodetic observations play an important role in detecting changes in mass and spatial variations in the Earth's gravity field. The Gravity Recovery And Climate Experiment (GRACE) observed spatial variations in the Earth's gravity field over the past ten years. The satellite detects mass variations in the Earth system including geophysical, hydrological and atmospheric shifts. GRACE itself is not able to separate the GIA from mass balance changes and, due to the insufficient geological and geomorphological database, it is not possible to model the GIA effect accurately for Antarctica. However, the results from GRACE can be compared with other scientific results, coming from other geodetic observations such as satellite altimetry and GPS or by the use of geological observations. In our contribution we compare the GRACE data with recorded precipitation patterns and mass anomalies over East Antarctica to separate the observed GRACE signal into its two components: GIA as a result of mass loss and present day surface load changes due to possible snow/ice accumulation.

Kallenberg, B.; Tregoning, P.

2012-04-01

283

Rare earths  

Science.gov (United States)

Global mine production of rare earths was estimated to have declined slightly in 2012 relative to 2011 (Fig. 1). Production in China was estimated to have decreased to 95 from 105 kt (104,700 from 115,700 st) in 2011, while new mine production in the United States and Australia increased.

Gambogi, J.

2013-01-01

284

Impact Earth  

Science.gov (United States)

This planetarium show teaches about meteors, meteorites, asteroids, and comets. It includes results from NASA missions and about the dangers they can pose to life on Earth. It is created for full-dome theaters but can also be shown in flat version for TVs and computer monitors. Shows the effects of the Chixulub and Tungusta events, plus the Pallasite impact that resulted in the Brenham meteorite fall. Describes ways that asteroid hunters seek new objects in the Solar System, and how ground-penetrating radar is used to find meteorites that have reached the Earth's surface and ancient craters under the desert. 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. Created for informal science venues (digital planetariums), it is also useful as ancillary material for middle school science. Created under NASA Cooperative Agreement NCC5-316 to Rice University in conjunction with the Houston Museum of Natural Science as part of the "Immersive Earth" project, part of the REASoN program.

Patricia Reiff

2009-05-01

285

Earth Walk  

Science.gov (United States)

In this hands-on and feet-on excursion, learners take a science walk to visualize the planet's immense size and numerous structures, without the usual scale and ratio dimensions found in most textbooks. Learners also compare their body's height to a scaled-down Earth.

Eric Muller

1995-01-01

286

Visible Earth  

Science.gov (United States)

This Web site provides a searchable directory of NASA Earth science images, animations and data visualizations. Most resources are available digitally at multiple resolutions, with captions and metadata. Users can search the database using full text and advanced searches by topic, keyword, sensor, location, parameter, and dates.

2001-01-01

287

Earth's magnetosphere  

International Nuclear Information System (INIS)

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

288

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

International Nuclear Information System (INIS)

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

289

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

290

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.

291

Errors in potassium balance  

Energy Technology Data Exchange (ETDEWEB)

Six overweight adult subjects given a low calorie diet containing adequate amounts of nitrogen but subnormal amounts of potassium (K) were observed on the Clinical Research Center for periods of 29 to 40 days. Metabolic balance of potassium was measured together with frequent assays of total body K by /sup 40/K counting. Metabolic K balance underestimated body K losses by 11 to 87% (average 43%): the intersubject variability is such as to preclude the use of a single correction value for unmeasured losses in K balance studies.

Forbes, G.B.; Lantigua, R.; Amatruda, J.M.; Lockwood, D.H.

1981-01-01

292

Balance in Random Trees  

OpenAIRE

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

Azer Akhmedov; Warren Shreve

2014-01-01

293

Errors in potassium balance  

International Nuclear Information System (INIS)

Six overweight adult subjects given a low calorie diet containing adequate amounts of nitrogen but subnormal amounts of potassium (K) were observed on the Clinical Research Center for periods of 29 to 40 days. Metabolic balance of potassium was measured together with frequent assays of total body K by 40K counting. Metabolic K balance underestimated body K losses by 11 to 87% (average 43%): the intersubject variability is such as to preclude the use of a single correction value for unmeasured losses in K balance studies

294

Properties of Balanced Permutations  

OpenAIRE

This paper takes a close look at balanced permutations, a recently developed sample reuse method with applications in bioinformatics. It turns out that balanced permutation reference distributions do not have the correct null behavior, which can be traced to their lack of a group structure. We find that they can give p-values that are too permissive to varying degrees. In particular the observed test statistic can be larger than that of all B balanced permutations of a data set with a probabi...

Southworth, Lucinda K.; Kim, Stuart K.; Owen, Art B.

2009-01-01

295

Numerical Results of Earth's Core Accumulation 3-D Modelling  

Science.gov (United States)

For a long time as a most convenient had been the model of mega impact in which the early forming of the Earth's core and mantle had been the consequence of formed protoplanet collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,3] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone. Only after the increasing of the gravitational radius, the growing area of the future core can save also the silicate envelope fragments. All existing dynamical accumulation models are constructed by using a spherical-symmetrical model. Hence for understanding the further planet evolution it is significant to trace the origin and evolution of heterogeneities, which occur on the planet accumulation stage. In that paper we are modeling distributions of temperature, pressure, velocity of matter flowing in a block of 3D- spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach. The numerical algorithm of the problem solution in velocity-pressure variables is constructed on the base of the splitting method. The velocity field and pressure field we obtain using the checkerboard grid. The occurring and evolution of the initial heterogeneities in the growing planets is caused by heterogeneous distribution of falling accumulated bodies. 1.V.N. Anfilogov and Yu.V.Khachai A Possible Scenario of Material Differentiation at the Ini-tial Stage of the Earth's Formation // Doklady Earth Sciences. V. 403 A.N 6. 2005. 954-957 Transl. from Doklady Akademii Nauk.v.403.N 6.2005.803-806. 2.Khachay Yu., Anfilogov V. VARIANTS OF TEMPERATURE DISTRIBUTIONS IN THE EARTH ON ITS ACCUMULATION // Proc. of the 6th Orlov Conf. "The study of the Earth as a planet by methods of geophysics, geodesy and astronomy" K.: Akad. 2010.197-202. 3.V.N. Anfilogov and Yu.V.Khachay Differentiation of the mantle matter during the process of the Earth's accumulation and early crust formation // Litosphere, 2012, N6, 3-15.

Khachay, Yurie; Anfilogov, Vsevolod

2013-04-01

296

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 ...

297

Improving Balance with Tai Chi  

Science.gov (United States)

... 8428 · INFO@VESTIBULAR.ORG · WWW.VESTIBULAR.ORG Improving Balance with Tai Chi By the Vestibular Disorders Association ... by people of all ages and physical ability. Balance benefits of Tai Chi Tai Chi improves balance ...

298

Exercise to Improve Your Balance  

Science.gov (United States)

... Go4Life Exercise to Improve Your Balance Having good balance is important for many everyday activities, such as ... try adding the following challenges to help your balance even more: l Start by holding on to ...

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

National Energy Balance-1987  

International Nuclear Information System (INIS)

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

301

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.

302

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.

Scripps Institution of Oceanography

303

Detailed balance and entanglement  

Science.gov (United States)

We study a connection between quantum detailed balance, which is a concept of importance in statistical mechanics, and entanglement. We also explore how this connection fits into thermofield dynamics.

Duvenhage, Rocco; Snyman, Machiel

2015-04-01

304

The Balancing Act  

Energy Technology Data Exchange (ETDEWEB)

This essay is being proposed as part of a book titled: "Motherhood: The Elephant in the Laboratory." It offers professional and personal advice on how to balance working in the research field with a family life.

Fowler, Kimberly M.

2008-05-01

305

Balance and Stroke Risk  

Medline Plus

Full Text Available ... indicator of brain health. He says individuals showing poor balance on one leg should receive increased attention, ... MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated on ...

306

The Balanced Literacy Diet.  

Science.gov (United States)

Describes professional development program in Ontario school district to improve student reading and writing skills. Program used food-pyramid concepts to help teacher learn to provide a balanced and flexible approach to literacy instruction based on student needs. (PKP)

Willows, Dale

2002-01-01

307

Balanced-bellows spirometer  

Science.gov (United States)

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

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

1972-01-01

308

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

309

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

310

Judicial Checks and Balances  

OpenAIRE

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

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

2004-01-01

311

Momentum balance and flux conservation in model magnetospheric magnetic fields  

International Nuclear Information System (INIS)

We have tested four recent quantitative magnetospheric magnetic field models to determine whether the magnetic field configuration is consistent with a balance of forces between the J x B force and the gradient of the pressure. A necessary condition for the models to be consistent with an isotropic pressure distribution is that curl (J x B) vanish. None of the models (Olson-Pfitzer, Tsyganenko, Hedgecock-Thomas, and Beard) meet this requirement: Our analysis indicates that the models are intrinsically inconsistent with momentum balance with any isotropic pressure distribution. We have also, for purposes of comparison, examined delxB. In certain models this can be nonzero

312

Plasma pressure and anisotropy inferred from the Tsyganenkomagnetic field model  

Directory of Open Access Journals (Sweden)

Full Text Available A numerical procedure has been developed to deduce the plasma pressure and anisotropy from the Tsyganenko magnetic field model. The Tsyganenko empirical field model, which is based on vast satellite field data, provides a realistic description of magnetic field configuration in the magnetosphere. When the force balance under the static condition is assumed, the electromagnetic J×B force from the Tsyganenko field model can be used to infer the plasma pressure and anisotropy distributions consistent with the field model. It is found that the J×B force obtained from the Tsyganenko field model is not curl-free. The curl-free part of the J×B force in an empirical field model can be balanced by the gradient of the isotropic pressure, while the nonzero curl of the J×B force can only be associated with the pressure anisotropy. The plasma pressure and anisotropy in the near-Earth plasma sheet are numerically calculated to obtain a static equilibrium consistent with the Tsyganenko field model both in the noon-midnight meridian and in the equatorial plane. The plasma pressure distribution deduced from the Tsyganenko 1989 field model is highly anisotropic and shows this feature early in the substorm growth phase. The pressure anisotropy parameter ?P, defined as ?P=1-PVertP, is typically ~0.3 at x ? -4.5RE and gradually decreases to a small negative value with an increasing tailward distance. The pressure anisotropy from the Tsyganenko 1989 model accounts for 50% of the cross-tail current at maximum and only in a highly localized region near xsim-10RE. In comparison, the plasma pressure anisotropy inferred from the Tsyganenko 1987 model is much smaller. We also find that the boundary conditions have significant effects on the plasma pressure distributions and have to be considered carefully.

F. Cao

313

Earth Observatory  

Science.gov (United States)

This Web site includes shares the images, stories and discoveries that emerge from NASA Earth science research, including its satellite missions, in-the-field research and climate models. View global maps of NASA data, check out the Image of the Day and images of current events, and read feature articles and blogs. Also includes special collections of NASA images, including the World of Change series, which documents how our planet’s land, oceans, atmosphere and Sun are changing over time.

2011-01-01

314

Rolling-Convolute Joint For Pressurized Glove  

Science.gov (United States)

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

Kosmo, Joseph J.; Bassick, John W.

1994-01-01

315

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

316

Automatic force balance calibration system  

Science.gov (United States)

A system for automatically calibrating force balances is provided. The invention uses a reference balance aligned with the balance being calibrated to provide superior accuracy while minimizing the time required to complete the calibration. The reference balance and the test balance are rigidly attached together with closely aligned moment centers. Loads placed on the system equally effect each balance, and the differences in the readings of the two balances can be used to generate the calibration matrix for the test balance. Since the accuracy of the test calibration is determined by the accuracy of the reference balance and current technology allows for reference balances to be calibrated to within .+-.0.05%, the entire system has an accuracy of a .+-.0.2%. The entire apparatus is relatively small and can be mounted on a movable base for easy transport between test locations. The system can also accept a wide variety of reference balances, thus allowing calibration under diverse load and size requirements.

Ferris, Alice T. (Inventor)

1996-01-01

317

The Balance Evaluation Systems Test (BESTest) to Differentiate Balance Deficits  

OpenAIRE

Background: Current clinical balance assessment tools do not aim to help therapists identify the underlying postural control systems responsible for poor functional balance. By identifying the disordered systems underlying balance control, therapists can direct specific types of intervention for different types of balance problems.

Horak, Fay B.; Wrisley, Diane M.; Frank, James

2009-01-01

318

Anisotropic Alfven-ballooning modes in Earth`s magnetosphere  

Energy Technology Data Exchange (ETDEWEB)

The authors have carried out a theoretical analysis of the stability and parallel structure of coupled shear Alfven and slow magnetosonic waves in Earth`s inner magnetosphere (i.e., at equatorial distances between about five and ten Earth radii) including effects of finite anisotropic plasma pressure. Multiscale perturbation analysis of the anisotropic Grad-Shafranov equation yields an approximate self-consistent magnetohydrodynamic (MHD) equilibrium. This MHD equilibrium is used in the numerical solution of a set of eigenmode equations which describe the field line eigenfrequency, linear stability, and parallel eigenmode structure. The authors call these modes anisotropic Alfven-ballooning modes. The main results are: (1) The field line eigenfrequency can be significantly lowered by finite pressure effects. (2) The parallel mode structure of the transverse wave components in fairly insensitive to changes in the plasma pressure, but the compressional magnetic component can become highly peaked near the magnetic equator as a result of increased pressure, especially when P{perpendicular}>P{parallel} (here P{perpendicular} and P{parallel} are the perpendicular and parallel plasma pressure). (3) For the isotropic (P{parallel}=P{perpendicular}=P) case ballooning instability can occur when the ratio of the plasma pressure to the magnetic pressure exceeds a critical value {beta}{sub 0}{sup B}{approx} 3.5 at the equator. (4) Compared to the isotropic case the critical beta value is lowered by anisotropy. (5) The authors use a {beta}-{delta} stability diagram to display the regions of instability with respect to the equatorial values of the parameters {beta} and {delta}, where {beta} = (1/3)({beta}{parallel}+2{beta}{perpendicular}) is an average beta value and {delta}=1-P{parallel}/P{perpendicular} is a measure of the plasma anisotropy. The diagram is divided into regions corresponding to the firehose, mirror and ballooning instabilities. 31 refs., 8 figs.

Chan, A.A. [Rice Univ., Houston, TX (United States); Xia, M. [Peking Univ., Beijing (China); Chen, L. [Univ. of California, Irving, CA (United States)

1994-09-01

319

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

320

Characteristic of VHF plasma produced by balanced power feeding  

International Nuclear Information System (INIS)

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

321

Balanced Integrated Regulatory Oversight  

International Nuclear Information System (INIS)

Reactor safety, protecting the public health and safety, and protecting the environment must always be the nuclear regulator's top priorities. Enabling the use of nuclear power for the benefit of society, while protecting the public and the environment requires the regulator to balance many factors. In addition, the regulator is only one part of the overall government that must consider many factors as it carries out its societal responsibilities. Some of the factors that must be balanced and the practical impacts on how the regulator carries out its responsibilities will be addressed. The first International Conference on Effective Regulatory Systems, held in Moscow, Russian Federation, in 2006, focused on safety and security challenges with a goal of improving regulatory effectiveness through cooperation and sharing of information and best practices. The challenge of meeting both safety and security objectives is one example of potentially competing programmes that must be balanced. Other balances that must be evaluated include the benefits of safety improvements compared to the cost of implementation, the use of deterministic and probabilistic approaches, communication openness balanced with the protection of information that could be used for detrimental purposes, and timeliness of regulatory decision making balanced with the need to perform quality work in support of oversight responsibilities. A balanced and integrated approach to regulatory oversight is vital tpproach to regulatory oversight is vital to ensuring that the regulatory body remains effective in its mission to enable the use of nuclear power while protecting the public and the environment. This concept is applicable to nations beginning a nuclear programme as well as established and experienced regulatory bodies. (author)

322

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

323

Pingos on Earth and Mars  

Science.gov (United States)

Pingos are massive ice-cored mounds that develop through pressurized groundwater flow mechanisms. Pingos and their collapsed forms are found in periglacial and paleoperiglacial terrains on Earth, and have been hypothesized for a wide variety of locations on Mars. This literature review of pingos on Earth and Mars first summarizes the morphology of terrestrial pingos and their geologic contexts. That information is then used to asses hypothesized pingos on Mars. Pingo-like forms (PLFs) in Utopia Planitia are the most viable candidates for pingos or collapsed pingos. Other PLFs hypothesized in the literature to be pingos may be better explained with other mechanisms than those associated with terrestrial-style pingos.

Burr, Devon M.; Tanaka, Kenneth L.; Yoshikawa, Kenji

2009-05-01

324

Seasonal contributions of precipitation to recharge: Completely different estimates from water budget and stable isotope balance  

International Nuclear Information System (INIS)

The seasonal recharge into a karstified aquifer system of the Franconian Alb, southern Germany, was determined for 1995 and 1996 by balancing stable isotope composition of precipitation with that of ground water and by water balancing applying the empirical formula of Haude which introduces climatic parameters like mean daily temperature, humidity, and precipitation as well as the natural features of earth's surface

325

The oxygen and carbon dioxide balance in the earth's atmosphere  

Science.gov (United States)

The oxygen-carbon dioxide cycle is described in detail, and steps which are sensitive to perturbation or instability are identified. About half of the carbon dioxide consumption each year in photosynthesis occurs in the oceans. Phytoplankton, which are the primary producers, have been shown to assimilate insecticides and herbicides. The impact of such materials on phytoplankton photosynthesis, both direct and as the indirect result of detrimental effects higher up in the food chain, cannot be assessed. Net oxygen production is very small in comparison with the total production and occurs almost exclusively in a few ocean areas with anoxic bottom conditions and in peat-forming marshes which are sensitive to anthropogenic disturbances. The carbon dioxide content of the atmosphere is increasing at a relatively rapid rate as the result of fossil fuel combustion. Increases in photosynthesis as the result of the hothouse effect may in turn reduce the carbon dioxide content of the atmosphere, leading to global cooling.

Johnson, F. S.

1975-01-01

326

Algebra Balance Scales  

Science.gov (United States)

This online manipulative features a virtual balance scale. It offers students an experimental way to learn about solving linear equations involving negative or positive numbers. The applet presents an equation for the student to illustrate by balancing the scale using blue blocks for positive units and variables and red balloons for negative units and variables. The student then works with the arithmetic operations to solve the equation. A record of the steps taken by the student is shown on the screen and on the scale. The applet reinforces the idea that what is done to one side of an equation must be done to the other side to maintain balance. Instructions for using the applet, background information about solving equations, and teaching suggestions are included.

2010-06-30

327

Balanced Modulation for Nonvolatile Memories  

OpenAIRE

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

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

2012-01-01

328

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

329

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

330

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

331

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

OpenAIRE

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

332

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

333

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

334

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.

335

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.)

336

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

337

Theory of global balance  

Directory of Open Access Journals (Sweden)

Full Text Available The article elaborates the content of the theory of global balance concept, corroborating it with historical evidences. The world is regarded in terms of “human-enterprise-state” system, and world history – through the matrix consisting of consecutive and interconnected events, which can be not only logically explained but also prognosticated.

Kurbatov Nikolay Ivanovich

2012-05-01

338

Sweetly Balanced Equations  

Science.gov (United States)

In this (edible) activity, learners balance chemical equations using different kinds and colors of candy that represent different atoms. Learners will work in pairs and explore conservation of atoms. One partner will use his/her candy to simulate the reactant (left) side of the equation and the other partner will use his/her candy to simulate the product (right) side.

Don Rathjen

2003-01-01

339

Asymmetric Earth  

Science.gov (United States)

The net rotation, or so-called W-ward drift of the lithosphere, implies a decoupling of the plates relative to the underlying asthenosphere, and a relative "E-ward" mantle flow. This polarized flow can account for a number of asymmetries. When comparing the W-directed versus the E- to NE-directed subduction zones, as a general observation, they have the subduction hinge diverging versus converging relative to the upper plate; low versus high topography and structural elevation respectively; deep versus shallow trenches and foreland basins; shallow versus deep decollement; low versus high basement involvement; high versus low heat flow and gravity anomaly; shallow versus deep asthenosphere; etc. The western limbs of rift zones show S-waves faster in the lithosphere and slower in the asthenosphere with respect to the eastern limb. The asymmetry can be recognized when moving along the "tectonic equator", which describes the fastest flow of plates relative to the mantle, and it undulates relative to the geographic equator. In our reconstructions, the best fit for the tectonic equator has a pole of rotation at latitude -56.4° and longitude 136.7°, with an angular velocity of 1.2036°/Ma. Shear-wave splitting alignments tend to parallel the tectonic flow, apart along the subduction zones where they become orthogonal, as a flow encountering an obstacle. The tectonic equator lies close to the revolution plane of the Moon about the Earth. All these data and interpretations point for an asymmetric Earth, whose nature appears to be related to the rotation and its tidal despinning, combined with the thermal cooling of the planet. However, this model has been questioned on the basis of the high viscosity so far inferred in the asthenosphere. Preliminary modelling shows that the tidal oscillation can generate gravitational wave propagation in the lithosphere, and the wave velocity can increase with the decrease of the asthenospheric viscosity.

Doglioni, Carlo; Carminati, Eugenio; Crespi, Mattia; Cuffaro, Marco; Ismail-Zadeh, Alik; Levshin, Anatoli; Panza, Giuliano F.; Riguzzi, Federica

2010-05-01

340

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

341

Earth-Sun Geometry - Earth Revolution Animation  

Science.gov (United States)

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

Dr. Michael Pidwirny

342

Age-related neuromuscular function and dynamic balance control during slow and fast balance perturbations.  

Science.gov (United States)

This study investigated age-related differences in dynamic balance control and its connection to reflexes and explosive isometric plantar flexor torque in 19 males (9 Young aged 20-33 yr, 10 Elderly aged 61-72 yr). Dynamic balance was measured during Slow (15 cm/s) and Fast (25 cm/s) anterior and posterior perturbations. H/M-ratio was measured at 20% of maximal M-wave (H/M20%) 10, 30, and 90 ms after perturbations. Stretch reflexes were measured from tibialis anterior and soleus during anterior and posterior perturbations, respectively. In Slow, Elderly exhibited larger peak center-of-pressure (COP) displacement (15%; P posterior (51%; P posterior perturbations, and rapid sensory feedback is generally important for balance perturbation recovery. PMID:24047908

Piirainen, Jarmo M; Linnamo, Vesa; Cronin, Neil J; Avela, Janne

2013-12-01

343

Thermodynamics of the Earth  

Science.gov (United States)

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 × 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 Grüneisen parameter, invokes insights that have disappeared from view in 'mainstream' physics.

Stacey, Frank D.

2010-04-01

344

Balance Control and Knee Osteoarthritis Severity  

Science.gov (United States)

Objective To investigate balance control according to the severity of knee osteoarthritis (OA) using clinical tests and Tetra-ataxiometric posturography (Tetrax®). Method A total 80 patients with primary knee OA classified according to American College of Rheumatology criteria, and 40 age-matched controls were enrolled in this study. Of those with OA, 39 patients had mild OA (Kellgren-Lawrence [KL] grade 1, 2) and the other 41 had moderate to severe OA (KL grade 3, 4). The postural control capabilities of the subjects were assessed using the timed up and go test (TUG), Berg balance scale (BBS), and Tetrax®, which utilizes two paired force plates to measure vertical pressure fluctuations over both heels and forefeet. The subjects were checked for their stability index (ST), Fourier index, weight distribution index (WDI), and synchronization index (SI) in eight positions using Tetrax®. Results Patients with moderate to severe OA exhibited significantly higher stability indices in all positions than patients with mild OA. The Fourier index was also higher in patients with moderate to severe OA than in patients with mild OA. However, the weight distribution index and synchronization of both heels and forefeet were not significantly different in the three groups. Conclusion These findings suggest that patients with moderate to severe OA have more deficits in balance control than those with mild disease. Therefore, evaluation of balance control and education aimed at preventing falls would be useful to patients with knee OA. PMID:22506194

Kim, Hee-Sang; Yun, Dong Hwan; Yoo, Seung Don; Kim, Dong Hwan; Jeong, Yong Seol; Yun, Jee-Sang; Hwang, Dae Gyu; Jung, Pil Kyo

2011-01-01

345

Application of Pascal Principle in Earth Science  

Science.gov (United States)

The Pascal experiment is interpreted and the chamber is roughly defined. Pascal experiment in relation to Pascal principle compared with a chamber in the earth crust. It is conclude that: 1: The pressure (P) inside the Pascal's cylinder is the combination of two pressure; the external pressure (P1) and the hydraulic pressure (P2). Pc=P1+P2 The direction of the force is from top to bottom. In the case of the chamber the pressure is Pch=P1-P2 and its positive direction is regarded to be from bottom to top. P1 is the external pressure, and is the maximum pressure applied to chamber .The external pressure creates a constant internal pressure throughout the chamber .The magnitude of the constant pressure is based on the litho static pressure of the bottom of the chamber; because it is the maximum pressure that the chamber is connected. P1=?1gH+?2gh Where H is the overburden thickness, h is the highness of the chamber, ?1 is the density of the overburden and ?2 is density of country rock. The hydrostatic pressure within the chamber is P2=?3gh. Also ?3 is the density of the chamber. So the pressure inside the chamber would be: Pch=P1-P2 then Pch=?1gH+(?2-?3)gh. The equation above means that, the chamber pressure equals to the overburden pressure plus Archimedes pressure. 2: The word squeezing which is a vulgar word has an important physical meaning that is ((Pascal principle driving movement)).In another word, almost all movements, related to chambers, within the earth are a squeezing event which's, driving force is the steady constant pressure mentioned above. Any change in this pressure depends on the rupturing of the chamber and the behavior of the movement of the chamber matter. 3: If we provide a safety valve on piston of the Pascal's cylinder and increase the load we see the safety valve bursts and the matter inside the cylinder squeeze out .The pressure is from top to bottom but the movement is from bottom to top. The direction of force has changed 180° degree. This is Pascal's miracle and displays the all movements that pierce the earth surface and let the matter squeeze out.

Samimi Namin, M.

2009-12-01

346

The Lifeworld Earth and a Modelled Earth  

Science.gov (United States)

The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the Earth, science's view of the Earth as an object—a celestial body—has been applied. I reanalysed data published in Vosniadou and Brewer's (Cognit psychol 24:535-585, 1992) seminal paper. According to my reanalysis of their interview material, it is plausible to conclude that the Earth as an infinite surface is the way to experience the Earth. Further, the `dual Earth model' is the first model of the Earth as an object. I conclude that experiences in the lifeworld need to be taken into consideration more seriously in science education research.

Juuti, Kalle

2014-08-01

347

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 ...

348

Older Adults and Balance Problems  

Medline Plus

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

349

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. ...

350

Ballet Balance Strategies  

OpenAIRE

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

2004-01-01

351

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.)

352

Algebra Balance Scales - Negatives  

Science.gov (United States)

This site provides a virtual balance on which the student can represent (and then solve) simple linear equations with integer answers. Conceptually, positive weights (unit-blocks and x-boxes) push the pans of the scale downward. Negative values are represented by balloons which can be attached to the pans of the scale. The student can then manipulate the weights to solve the equation while simultaneously seeing a visual display of these effects on the equation.

Utah State University

2009-07-01

353

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.

354

France's energy balances  

International Nuclear Information System (INIS)

Several terminological definitions of words and concepts used for the establishment of France's energy balance (i.e. the supply and utilization of energy) are presented, taken from the Energy dictionary, published in 1992 by the world Energy Council: primary, secondary, final and useful energy. Statistics concerning energy production, importation and exportation, consumption, and costs are discussed, showing the market share evolution of the different energy types; the France's energy independence ratio has increased from 22% in 1973 to 51% in 1995

355

Balance-bot  

OpenAIRE

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

356

Using balance program for energy balance analysis  

International Nuclear Information System (INIS)

Belong with development of the economy, the energy consumption will be increased very high in the future. Vietnam has a broad range of mineral resources. There is considerable energy potential on form of coal, oil and gas, hydropower and fuel wood, Recently, Vietnam is an exporter of energy. But in next two decades, the energy sources will be enough to meet requirement? The model BALANCE was used to solve energy planning problem. The objective of this model is analyzing energy system and built an energy development strategy in long term. After using model, the results are: total coal consumption will be 17.440 Mtoe in 2020 and 32 Mtoe in 2030. the biggest coal consumer is electricity sector. Total oil production consumption will be more than 30 Mtoe in 2020 and more than 50 Mtoe in 2030. If we have 4 refinery factories from now to 2030, total oil products import will be 11 Mtoe in 2020 and 25 Mtoe in 2030. The amount of gas supply in 2030 will be 20 billions m3 (18 Mtoe). Vietnam needs to import 8.3 Mtoe more, Vietnam will become an energy importer in next 15 years. In previous years, the economy of Vietnam was mainly based on agricultural production. But Vietnam is moving rapidly from an agricultural to an industrial economy. Belong with the development of the economy, energy consumption increases very fast. So which energy sources should be used first and when it will be use...are questions need to be answered. Vietnam has a broad range of mineral resourcetnam has a broad range of mineral resources. There is considerable energy potential on form of coal, oil and gas, hydropower and fuel wood. Recently, Vietnam is energy exporter, but in near future Vietnam has enough energy to meet demand or we need to import from outside? It should be studied carefully to answer. (author)

357

Academic Earth  

Science.gov (United States)

Academic Earth provides videos of lectures by top scholars in "Subjects" that range from Astronomy to Entrepreneurship to Religion, from "Universities" as celebrated as MIT, Berkeley, Harvard, and Stanford. Visitors must register to view the lectures, but registration is free. There are over 1500 video lectures available, with more being added everyday. In addition to viewing the lectures available by subject or university, visitors can choose by "Instructors" or by "Playlists". When visitors click on "Playlists" at the top of the homepage, they will see a list of lectures by theme, by several different instructors, and a grade given to the lecture series. A good example is the 6-part lecture entitled "Understanding the Financial Crisis" by four different instructors. The series is given a grade overall, in this case, an A-, and when visitors click on "See all 6 lectures" at the bottom of the series' description, they will be taken to the page with the links to the individual lectures, as well as shown the grade given each individual lecture. Visitors can even keep a playlist of their favorite lectures or download the lectures. Visitors should definitely check out the Frequently Asked Questions page, accessible by the "FAQ" link at the bottom of the website.

358

Aluminium at terapascal pressures.  

Science.gov (United States)

Studying materials at terapascal (TPa) pressures will provide insights into the deep interiors of large planets and chemistry under extreme conditions. The equation of state of aluminium is of interest because it is used as a standard material in shock-wave experiments and because it is a typical sp-bonded metal. Here we use density-functional-theory methods and a random-searching approach to predict stable structures of aluminium at multiterapascal pressures, finding that the low-pressure close-packed structures transform to more open structures above 3.2 TPa (nearly ten times the pressure at the centre of the Earth), with an incommensurate host-guest structure being stable over a wide range of pressures and temperatures. We show that the high-pressure phases may be described by a two-component model consisting of positive ions and interstitial electron 'blobs', and propose that such structures are common in sp-bonded materials up to multiterapascal pressures. PMID:20622863

Pickard, Chris J; Needs, R J

2010-08-01

359

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

360

Pressures on Youth in Sports  

Science.gov (United States)

The pressures on young athletes today, many of them brought on or exacerbated by parents, drive young athletes to attain perfection and win by any means necessary. For the young athlete, the challenges of learning how to balance schoolwork, social life, family time, and sports, not to mention other interests they might have, are far more intense…

Ungerleider, Steven

2003-01-01

361

Balance Disorders (For Parents)  

Science.gov (United States)

... sickness changes in heart rate and blood pressure fatigue seizures fear, anxiety, or panic depression Of course, symptoms involving kids' movement, sight, hearing — and just how they feel, day to day — ...

362

Ocular perfusion pressure in glaucoma.  

Science.gov (United States)

This review article discusses the relationship between ocular perfusion pressure and glaucoma, including its definition, factors that influence its calculation and epidemiological studies investigating the influence of ocular perfusion pressure on the prevalence, incidence and progression of glaucoma. We also list the possible mechanisms behind this association, and discuss whether it is secondary to changes in intraocular pressure, blood pressure or both. Finally, we describe the circadian variation of ocular perfusion pressure and the effects of systemic and topical medications on it. We believe that the balance between IOP and BP, influenced by the autoregulatory capacity of the eye, is part of what determines whether an individual will develop optic nerve damage. However, prospective, longitudinal studies are needed to better define the role of ocular perfusion pressure in the development and progression of glaucoma. PMID:24238296

Costa, Vital P; Harris, Alon; Anderson, Douglas; Stodtmeister, Richard; Cremasco, Fernanda; Kergoat, Helene; Lovasik, John; Stalmans, Ingborg; Zeitz, Oliver; Lanzl, Ines; Gugleta, Konstantin; Schmetterer, Leopold

2014-06-01

363

EarthLabs - Investigating Hurricanes: Earth's Meteorological Monsters  

Science.gov (United States)

Earth science is one of the most important tools that the global community needs to address the pressing environmental, social, and economic issues of our time. While, at times considered a second-rate science at the high school level, it is currently undergoing a major revolution in the depth of content and pedagogical vitality. As part of this revolution, labs in Earth science courses need to shift their focus from cookbook-like activities with known outcomes to open-ended investigations that challenge students to think, explore and apply their learning. We need to establish a new model for Earth science as a rigorous lab science in policy, perception, and reality. As a concerted response to this need, five states, a coalition of scientists and educators, and an experienced curriculum team are creating a national model for a lab-based high school Earth science course named EarthLabs. This lab course will comply with the National Science Education Standards as well as the states' curriculum frameworks. The content will focus on Earth system science and environmental literacy. The lab experiences will feature a combination of field work, classroom experiments, and computer access to data and visualizations, and demonstrate the rigor and depth of a true lab course. The effort is being funded by NOAA's Environmental Literacy program. One of the prototype units of the course is Investigating Hurricanes. Hurricanes are phenomena which have tremendous impact on humanity and the resources we use. They are also the result of complex interacting Earth systems, making them perfect objects for rigorous investigation of many concepts commonly covered in Earth science courses, such as meteorology, climate, and global wind circulation. Students are able to use the same data sets, analysis tools, and research techniques that scientists employ in their research, yielding truly authentic learning opportunities. This month-long integrated unit uses hurricanes as the story line by which students investigate the different interactions involved in hurricane generation, steering, and intensification. Students analyze a variety of visualization resources looking for patterns in occurrence and to develop an understanding of hurricane structure. They download archived data about past hurricanes and produce temporal and spatial plots to discover patterns in hurricane life cycles. They investigate the relationship between hurricane wind speed and factors such as barometric pressure and sea surface temperature by conducting spreadsheet analyses on archived data. They also conduct hands-on laboratory experiments in order to understand the physical processes that underpin energy transfer in convection, condensation, and latent heat. These activities highlight Earth science as a vital, rich, invigorating course, employing state-of-the-art technologies and in-depth labs with high relevance for our daily lives and the future.

McDaris, J. R.; Dahlman, L.; Barstow, D.

2007-12-01

364

Integral design of reactor pressure vessels  

International Nuclear Information System (INIS)

Integral design applied to PWR pressure vessels allows one to obtain a moderate stress level due to a better balance of the material in the geometry; to reach a high quality and safety level of the pressure boundary; to improve the inservice inspection (ISI) operations; and to simplify the manufacturing operations. (author)

365

On the near surface momentum balance in the Yucatán Channel  

Directory of Open Access Journals (Sweden)

Full Text Available The horizontal momentum balance in the upper layers of the Yucatán Channel is examined for a period of 22 months, from September 1999 to June 2001, using subsurface currents from ADCP measurements at eight moorings across the channel, pressure measurements from coastal pressure sensors on both sides of the channel, QuickSCAT winds and AVISO altimetry data. The averaged balance between Isla Mujeres, México, and Cabo San Antonio, Cuba, (across-channel axis is basically geostrophic, but with contributions from ageostrophic terms, particularly friction against lower layers and to a lesser degree, the surface Ekman drift. Both the advective and the local acceleration terms appear unimportant in the side-to-side averaged balance. Interestingly, the averaged balance in along-channel axis is also mainly geostrophic; linear friction, Ekman drift, local acceleration and advective terms remain unimportant. An analysis of the balance from mooring to mooring across the channel indicates that in the region where the Yucatán current meanders, the advective terms with across-channel derivatives contribute significantly. The EOF modes of sea level anomalies from altimetry and the along-channel flow in the upper 90 m surface layer are correlated. Their two first modes are seemingly related to the transport fluctuations through the channel, but also to the along-channel pressure gradient and to the meandering of the Yucatán Current core, suggesting the presence of appreciable eddy-current interactions in the Channel.

A. Badan

2008-11-01

366

Well balanced finite volume methods for nearly hydrostatic flows  

International Nuclear Information System (INIS)

In numerical approximations of nearly hydrostatic flows, a proper representation of the dominant hydrostatic balance is of crucial importance: unbalanced truncation errors can induce unacceptable spurious motions, e.g., in dynamical cores of models for numerical weather prediction (NWP) in particular near steep topography. In this paper we develop a new strategy for the construction of discretizations that are 'well-balanced' with respect to dominant hydrostatics. The classical idea of formulating the momentum balance in terms of deviations of pressure from a balanced background distribution is realized here through local, time dependent hydrostatic reconstructions. Balanced discretizations of the pressure gradient and of the gravitation source term are achieved through a 'discrete Archimedes' buoyancy principle'. This strategy is applied to extend an explicit standard finite volume Godunov-type scheme for compressible flows with minimal modifications. The resulting method has the following features: (i) It inherits its conservation properties from the underlying base scheme. (ii) It is exactly balanced, even on curvilinear grids, for a large class of near-hydrostatic flows. (iii) It solves the full compressible flow equations without reference to a background state that is defined for an entire vertical column of air. (iv) It is robust with respect to details of the implementation, such as the choice of slope limiting functions, or the particularities of boundary conns, or the particularities of boundary condition discretizations

367

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

368

Energy balances 2005  

International Nuclear Information System (INIS)

Denmark's energy consumption was 800 PJ in 2005 when corrected for the fuel consumption used for producing electricity for export. The consumption is 0,5 % higher than in 2004. Since 1975, the energy consumption has been on the same level with minor fluctuations which are mainly due to the climate. The energy balances is an account of production, import and export, and consumption of energy. The consumption is accounted as physical amounts as well as gross consumption. Also, accounts are presented of the costs of energy in basis prices and in market prices, including excises on energy, CO2, and SO2. (LN)

369

Pan Balance-Expressions  

Science.gov (United States)

This interactive pan balance allows students to enter numeric or algebraic expressions and investigate the important concept of equivalence as well as practice arithmetic and algebraic skills. Users place an expression in each of the red and blue pans. These expressions may or may not include the variable x. If the expression is algebraic, a value for x is entered or adjusted by moving the slider. As the value of x changes, the results will be weighed and graphed. Instructions and exploration directions and questions are included.

2011-01-01

370

Energy balances 2002  

International Nuclear Information System (INIS)

Denmark's consumption of energy decreased almost 2% from 2001 to 2002, primarily due to the year 2002 being warmer than the year 2001. The total production of petroleum, natural gas, and renewable energy increased almost 6%. The production of petroleum increased 7%, the natural gas production was unchanged, and the production of wind energy increased 13%. The energy balances is an account of production, import and export, and consumption of energy. The consumption is accounted as physical amounts as well as gross consumption. Also an account is made of the costs of energy in basis prices and in market prices, including calculation of excises on energy, CO2 and SO2. (LN)

371

Modeling Early Earth Climate with GEEBITT  

Science.gov (United States)

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

Cindy Shellito

372

Why Earth Science?  

Science.gov (United States)

This article briefly describes Earth science. The study of Earth science provides the foundation for an understanding of the Earth, its processes, its resources, and its environment. Earth science is the study of the planet in its entirety, how its lithosphere, atmosphere, hydrosphere, and biosphere work together as systems and how they affect…

Smith, Michael J.

2004-01-01

373

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

Directory of Open Access Journals (Sweden)

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

Nicholson VP

2014-11-01

374

Resource Balancing Control Allocation  

Science.gov (United States)

Next generation aircraft with a large number of actuators will require advanced control allocation methods to compute the actuator commands needed to follow desired trajectories while respecting system constraints. Previously, algorithms were proposed to minimize the l1 or l2 norms of the tracking error and of the control effort. The paper discusses the alternative choice of using the l1 norm for minimization of the tracking error and a normalized l(infinity) norm, or sup norm, for minimization of the control effort. The algorithm computes the norm of the actuator deflections scaled by the actuator limits. Minimization of the control effort then translates into the minimization of the maximum actuator deflection as a percentage of its range of motion. The paper shows how the problem can be solved effectively by converting it into a linear program and solving it using a simplex algorithm. Properties of the algorithm are investigated through examples. In particular, the min-max criterion results in a type of resource balancing, where the resources are the control surfaces and the algorithm balances these resources to achieve the desired command. A study of the sensitivity of the algorithms to the data is presented, which shows that the normalized l(infinity) algorithm has the lowest sensitivity, although high sensitivities are observed whenever the limits of performance are reached.

Frost, Susan A.; Bodson, Marc

2010-01-01

375

Negative leave balances  

CERN Document Server

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

Human Resources Department

2005-01-01

376

Negative leave balances  

CERN Multimedia

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

Human Resources Department

2005-01-01

377

Analysis of radionuclides in two rare earth products  

International Nuclear Information System (INIS)

This paper describes a study on radioactivity change of rare-earth products after hydrometallurgy technology, using HPGe gamma spectrometer to analyze two rare earth products (LaCl3 and YCl). The results show that in the two samples exist natural radionuclides of thorium series and actinium-uranium series as well as other natural radionuclides 138La and 176Lu. In the sample of lanthanum chloride the radioactivity of actinium-uranium series and thorium series has not reached balance, the contents of their main progenies 226Ra and 227Th obviously changes with the time, reaching balance 60 days later, while YCl3 keeps stability. (authors)

378

Deuterium inventory in Tore Supra: Coupled carbon–deuterium balance  

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-07-15

379

Deuterium inventory in Tore Supra: Coupled carbon–deuterium balance  

International Nuclear Information System (INIS)

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

380

Deuterium inventory in Tore Supra: Coupled carbon-deuterium balance  

Science.gov (United States)

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

Pégourié, B.; Panayotis, S.; Languille, P.; Martin, C.; Dittmar, T.; Gauthier, E.; Hatchressian, J.-C.; Pascal, J.-Y.; Roubin, P.; Ruffe, R.; Tsitrone, E.; Vartanian, S.; Wang, H.; Beauté, A.; Bouvet, J.; Brosset, C.; Bucalossi, J.; Cabié, M.; Caprin, E.; Courtois, X.; Dachicourt, R.; Delchambre, E.; Dominici, C.; Douai, D.; Ekedahl, A.; Gunn, J. P.; Hakola, A.; Jacob, W.; Khodja, H.; Likonen, J.; Linez, F.; Litnovsky, A.; Marandet, Y.; Markelj, S.; Martinez, A.; Mayer, M.; Meyer, O.; Monier-Garbet, P.; Moreau, P.; Negrier, V.; Oddon, P.; Pardanaud, C.; Pasquet, B.; Pelicon, P.; Petersson, P.; Philipps, V.; Possnert, G.; Reiter, D.; Roth, J.; Roure, I.; Rubel, M.; Saint-Laurent, F.; Samaille, F.; Vavpeti?, P.

2013-07-01

381

Exploring Earth from Space  

Science.gov (United States)

This set of lithographs from the ISS EarthKAM program contains an educators' guide, student information and worksheets, and several Earth photos taken from the Space Shuttle. Shuttle astronauts and the ISS EarthKAM program provide photos of our planet from the unique perspective of Earth orbit. This resource can enhance students' studies of Earth and space science, geography, social studies, mathematics, and educational technologies.

382

Tetrahedrally coordinated carbonates in Earth’s lower mantle  

Science.gov (United States)

Carbonates are the main species that bring carbon deep into our planet through subduction. They are an important rock-forming mineral group, fundamentally distinct from silicates in the Earth’s crust in that carbon binds to three oxygen atoms, while silicon is bonded to four oxygens. Here we present experimental evidence that under the sufficiently high pressures and high temperatures existing in the lower mantle, ferromagnesian carbonates transform to a phase with tetrahedrally coordinated carbons. Above 80?GPa, in situ synchrotron infrared experiments show the unequivocal spectroscopic signature of the high-pressure phase of (Mg,Fe)CO3. Using ab-initio calculations, we assign the new infrared signature to C–O bands associated with tetrahedrally coordinated carbon with asymmetric C–O bonds. Tetrahedrally coordinated carbonates are expected to exhibit substantially different reactivity than low-pressure threefold coordinated carbonates, as well as different chemical properties in the liquid state. Hence, this may have significant implications for carbon reservoirs and fluxes, and the global geodynamic carbon cycle.

Boulard, Eglantine; Pan, Ding; Galli, Giulia; Liu, Zhenxian; Mao, Wendy L.

2015-02-01

383

Energy Balance, Climate, and Life - Work of M. Budyko  

Science.gov (United States)

This talk will review the work of Mikhail I. Budyko, author of "Climate and Life" and many other works, who died recently at age 81, in St Petersburg, Russia. He directed the Division for Climate Change Research at the State Hydrological Institute. We will explore Budyko's work in clarifying the role of energy balance in determining planetary climate, and the role of climate in regulating Earth s biosphere.

Cahalan, Robert F.

2004-01-01

384

Pressure Sores  

Science.gov (United States)

Pressure sores are areas of damaged skin caused by staying in one position for too long. They ... wheelchair, or are unable to change your position. Pressure sores can cause serious infections, some of which ...

385

Peer Pressure  

Science.gov (United States)

... for the school play. Back Continue When the Pressure's On Sometimes, though, the stresses in your life ... the ability to make good decisions. Back Continue Pressure Pointers Nearly everyone ends up in a sticky ...

386

40 CFR 1065.390 - PM balance verifications and weighing process verification.  

Science.gov (United States)

...the PM-stabilization environment for a minimum of 30 min, and the PM-stabilization environment has been within the specifications...6) Record the balance environment dewpoint, ambient temperature, and atmospheric pressure. (7)...

2010-07-01

387

Data needs for nutrient balances  

DEFF Research Database (Denmark)

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

Vinther, Finn Pilgaard

2011-01-01

388

Pressure ulcers  

OpenAIRE

Unrelieved pressure or friction of the skin, particularly over bony prominences, can lead to pressure ulcers, which affect up to one third of people in hospitals or community care, and one fifth of nursing home residents. Pressure ulcers are more likely in people with reduced mobility and poor skin condition, such as older people or those with vascular disease.

Grey, Joseph E.; Harding, Keith G.; Enoch, Stuart

2006-01-01

389

Air Pressure  

Science.gov (United States)

In this experiment, learners use a blow dryer and water bottle to observe and record changes in air pressure caused by changes in temperature. Educators can use this activity to explain how changes in temperature cause changes in air pressure which cause wind. This activity guide contains background information on air pressure, instructions for an extension experiment, and links to useful online resources.

University of Illinois

2009-01-01

390

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 and provides 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. SR using imperceptible stochastic electrical stimulation of the vestibular system (stochastic vestibular stimulation, SVS) applied to normal subjects has shown to improve the degree of association between the weak input periodic signals introduced via venous blood pressure receptors and the heart-rate responses. Also, application of SVS over 24 hours improves the long-term heart-rate dynamics and motor responsiveness as indicated by daytime trunk activity measurements in patients with multi-system atrophy, Parkinson s disease, or both, including patients who were unresponsive to standard therapy for Parkinson s disease. Recent studies conducted at the NASA JSC Neurosciences Laboratories showed that imperceptible SVS, when applied to normal young healthy subjects, leads to significantly improved balance performance during postural disturbances on unstable compliant surfaces. These studies have shown the benefit of SR noise characteristic optimization with imperceptible SVS in the frequency range of 0-30 Hz, and amplitudes of stimulation have ranged from 100 to 400 microamperes.

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

2012-01-01

391

Designing Multinational Electricity Balancing Markets:  

OpenAIRE

In today’s unbundled electricity markets, the balancing market is an intricate institutional arrangement that makes sure that the balance between electricity supply and demand is maintained. In the light of the development of a single electricity market in Europe, harmonization and integration of currently national balancing markets have received an increasing attention from governments, system operators, and regulators. This dissertation provides a systematic overview of the possibilit...

Veen, R. A. C.

2012-01-01

392

Are Social Networks Really Balanced?  

OpenAIRE

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

Estrada, Ernesto; Benzi, Michele

2014-01-01

393

ERBE data inversion. [Earth Radiation Budget Experiment  

Science.gov (United States)

The Earth Radiation Budget Experiment (ERBE) involves the use of a system of three spacecraft with instrument packages for measuring the earth's radiation balance to an accuracy which has been unattainable in previous experiments. The experiment is to determine the monthly averaged radiant exitances at te 'top of the atmosphere' (TOA) over the earth with a resolution of 250 km. The realization of this goal requires the conduction of high accuracy measurements, and the computation of the instantaneous radiant exitances from these measurements. The operation involved in this computation is called an 'inversion'. A third requirement is related to the computation of the daily and monthly averaged regional values from the instantaneous values. A brief description is provided of the algorithms for the inversion of the measurements to TOA radiant exitances, taking into account also the techniques which are used to validate the methods and results.

Smith, G. L.; Green, R.; Wielicki, B. A.; Suttles, J. T.; Avis, L. M.

1986-01-01

394

Energy balance climate models  

Science.gov (United States)

An introductory survey of the global energy balance climate models is presented with an emphasis on analytical results. A sequence of increasingly complicated models involving ice cap and radiative feedback processes are solved, and the solutions and parameter sensitivities are studied. The model parameterizations are examined critically in light of many current uncertainties. A simple seasonal model is used to study the effects of changes in orbital elements on the temperature field. A linear stability theorem and a complete nonlinear stability analysis for the models are developed. Analytical solutions are also obtained for the linearized models driven by stochastic forcing elements. In this context the relation between natural fluctuation statistics and climate sensitivity is stressed.

North, G. R.; Cahalan, R. F.; Coakley, J. A., Jr.

1981-01-01

395

Skin friction balance  

Science.gov (United States)

A skin friction balance uses a parallel linkage mechanism to avoid inaccuracies in skin friction measurement attributable to off-center normal forces. The parallel linkage mechanism includes a stationary plate mounted in a cage, and an upper and lower movable plate which are linked to each other and to the stationary plate throught three vertical links. Flexure pivots are provided for pivotally connecting the links and the plates. A sensing element connected to the upper plate moves in response to skin friction, and the lower plate moves in the opposite direction of the upper plate. A force motor maintains a null position of the sensing element by exerting a restoring force in response to a signal generated by a linear variable differential transformer (LVDT).

Ping, Tcheng (inventor); Supplee, Frank H., Jr. (inventor)

1989-01-01

396

Thermodynamics of the Earth  

International Nuclear Information System (INIS)

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

397

Energy Balance Models and Planetary Dynamics  

Science.gov (United States)

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

Domagal-Goldman, Shawn

2012-01-01

398

Simplicity in melt densification in multicomponent magmatic reservoirs in Earth’s interior revealed by multinuclear magnetic resonance  

OpenAIRE

Pressure-induced changes in properties of multicomponent silicate melts in magma oceans controlled chemical differentiation of the silicate earth and the composition of partial melts that might have formed hidden reservoirs. Although melt properties show complex pressure dependences, the melt structures at high pressure and the atomistic origins of these changes are largely unknown because of their complex pressure–composition dependence, intrinsic to multicomponent magmatic melts. Chemical...

Lee, Sung Keun

2011-01-01

399

Partitioning of potassium into the Earth's core 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. Our recent studies [Nomura+, 2011; Tateno+ in prep] showed the experimental evidence on the gravitational stability of basal magma ocean [Labrosse+, 2007] against the crystallized solid silicate at mid-lower mantle pressure conditions. This dense, incompatible element-rich reservoir would evolve in equilibrium with the liquid core at the core-mantel boundary pressure conditions during the early cooling history of the Earth and constrain the content of potassium in the Earth's core. Previous experimental studies on partitioning behaviors of potassium between liquid metal and silicate melt were limited to contamination by secondary fluorescence. The results show small effect of pressure but large effect of temperature on partitioning behaviors of K, suggesting the effect of Fe-K alloying [Lee&Jeanloz, 2003] at >25GPa was not occur or not significant at high temperature conditions. Assuming [K2O]silicate + [Fe]metal = 2[K]metal + [FeO]silicate, KD value is about >1 order higher than previous study [Corgne+, 2007] at >3500K with even sulfur-free system. The results are interpreted in respect to the thermal history of the Earth in the presentation together with the discussion of Si, O contents in the Earth's Core.

Nomura, R.; Hirose, K.; Ozawa, H.; Ohishi, Y.; Hirao, N.

2012-12-01

400

Laser techniques in high-pressure geophysics  

Science.gov (United States)

Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

Hemley, R. J.; Bell, P. M.; Mao, H. K.

1987-01-01

401

High-pressure elastic behavior of Ca4La6(SiO4)6(OH)2 a synthetic rare-earth silicate apatite: a powder X-ray diffraction study up to 9.33 GPa  

Science.gov (United States)

The compression behavior of a synthetic Ca4La6(SiO4)6(OH)2 has been investigated to about 9.33 GPa at 300 K using in situ angle-dispersive X-ray diffraction and a diamond anvil cell. No phase transition has been observed within the pressure range investigated. The values of zero-pressure volume V 0, K 0, and refined with a third-order Birch-Murnaghan equation of state are V 0 = 579.2 ± 0.1 Å3, K 0 = 89 ± 2 GPa, and . If is fixed at 4, K 0 is obtained as 110 ± 2 GPa. Analysis of axial compressible modulus shows that the a-axis ( K a0 = 79 ± 2 GPa) is more compressible than the c-axis ( K c0 = 121 ± 7 GPa). A comparison between the high-pressure elastic response of Ca4La6(SiO4)6(OH)2 and the iso-structural calcium apatites is made. The possible reasons of the different elastic behavior between Ca4La6(SiO4)6(OH)2 and calcium apatites are discussed.

Fan, Dawei; Wei, Shuyi; Ma, Maining; Chen, Zhiqiang; Li, Baosheng; Xie, Hongsen

2014-02-01

402

Balance Laws in Micromorphic Elasticity  

OpenAIRE

We derive the Eshelby stress tensor, the angular momentum tensor and the dilatational vector flux for micromorphic elasticity. We give the corresponding balance laws and the J, L, and M integrals. Also we discuss when the balance laws become conservation laws.

Lazar, Markus; Anastassiadis, Charalampos

2013-01-01

403

Calibration and Data Analysis of the MC-130 Air Balance  

Science.gov (United States)

Design, calibration, calibration analysis, and intended use of the MC-130 air balance are discussed. The MC-130 balance is an 8.0 inch diameter force balance that has two separate internal air flow systems and one external bellows system. The manual calibration of the balance consisted of a total of 1854 data points with both unpressurized and pressurized air flowing through the balance. A subset of 1160 data points was chosen for the calibration data analysis. The regression analysis of the subset was performed using two fundamentally different analysis approaches. First, the data analysis was performed using a recently developed extension of the Iterative Method. This approach fits gage outputs as a function of both applied balance loads and bellows pressures while still allowing the application of the iteration scheme that is used with the Iterative Method. Then, for comparison, the axial force was also analyzed using the Non-Iterative Method. This alternate approach directly fits loads as a function of measured gage outputs and bellows pressures and does not require a load iteration. The regression models used by both the extended Iterative and Non-Iterative Method were constructed such that they met a set of widely accepted statistical quality requirements. These requirements lead to reliable regression models and prevent overfitting of data because they ensure that no hidden near-linear dependencies between regression model terms exist and that only statistically significant terms are included. Finally, a comparison of the axial force residuals was performed. Overall, axial force estimates obtained from both methods show excellent agreement as the differences of the standard deviation of the axial force residuals are on the order of 0.001 % of the axial force capacity.

Booth, Dennis; Ulbrich, N.

2012-01-01

404

Adaptive Distributed Load Balancing Routing Mechanism for LEO Satellite IP Networks  

OpenAIRE

LEO (Low Earth Orbit) satellite constellation is an ideal scheme for the next generation wideband internet. The constellation is formed as a mesh-like network with inter satellite links (ISLs) which are equipped between the neighbor satellites for transmitting directly. As to the future wideband IP services, an efficient routing mechanism will play an important role in improving the performance and balancing the network traffic. An Adaptive Distributed Load Balancing Routing Mechanism (ADLB) ...

Xiao Ma

2014-01-01

405

High-pressure optical studies  

International Nuclear Information System (INIS)

High pressure experimentation may concern intrinsically high pressure phenomena, or it may be used to gain a better understanding of states or processes at one atmosphere. The latter application is probably more prevelant in condensed matter physics. Under this second rubric one may either use high pressure to perturb various electronic energy levels and from this pressure tuning characterize states or processes, or one can use pressure to change a macroscopic parameter in a controlled way, then measure the effect on some molecular property. In this paper, the pressure tuning aspect is emphasized, with a lesser discussion of macroscopic - molecular relationships. In rare earth chelates the efficiency of 4f-4f emission of the rare earth is controlled by the feeding from the singlet and triplet levels of the organic ligand. These ligand levels can be strongly shifted by pressure. A study of the effect of pressure on the emission efficiency permits one to understand the effect of ligand modification at one atmosphere. Photochromic crystals change color upon irradiation due to occupation of a metastable ground state. In thermochromic crystals, raising the temperature accomplishes the same results. For a group of molecular crystals (anils) at high pressure, the metastable state can be occupied at room temperature. The relative displacement of the energy levels at high pressure also inhibits the optical process. Effects on luminescence intensity are shown to be consistent. In the area of microscopic - molecular relationships, the effect of viscosity and dielectric properties on rates of non-radiative (thermal) and radiative emission, and on peak energy for luminescence is demonstrated. For systems which can emit from either of two excited states depending on the interaction with the environment, the effect of rigidity of the medium on the rate of rearrangement of the excited state is shown

406

RAM-SCB simulations of the near-Earth magnetosphere. Effect of plasma sheet conditions and magnetic coupling on the ring current/region 2 field-aligned currents  

International Nuclear Information System (INIS)

Complete text of publication follows. Accurately modeling the dynamics of the inner magnetosphere and near-Earth plasma sheet requires proper treatment of both kinetic drift physics and the interaction between particles and fields. During geomagnetic storms, the magnetic field is strongly depressed by the large ring current plasma pressure, and the changed field influences significantly the dynamic evolution of the plasma. To treat this self-consistent interaction we have developed a self-consistent inner magnetosphere code (RAM-SCB) by coupling the kinetic ring current-atmosphere interactions model (RAM) with an Euler potential-based 3D plasma equilibrium code. In our approach, the magnetic field is computed in force balance with the RAM anisotropic pressures (anisotropy being critically important for the excitation of EMIC waves), and then fed back into RAM. The model boundary has been expanded to 10 RE in the plasma sheet with plasma pressure/magnetic field boundary conditions prescribed there from observations or other models (empirical or first principles). This presentation will illustrate storm-time RAM-SCB simulations of the near-Earth magnetosphere, comparison of model results with available particle/field observations (from POLAR, CLUSTER, and GOES spacecraft), and physics insight into how the model results (plasma pressure, magnetic field, Region 2 currents) depend on 1). plasma sheet conditions (density, temperature, assumed ion composition) and temperature, assumed ion composition) and 2). the coupling between the magnetic field and plasma pressure.

407

ITER-Earthing  

OpenAIRE

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...

Perez, A.; Fasel, D.; Lister, Jb; Marle?taz, B.; Marmillod, P.; Siravo, U.

2010-01-01

408

Earth System Science  

Science.gov (United States)

Understanding climate requires understanding that Earth is a holistic system of dynamic, interacting components. Furthermore, understanding how the Earth system works is essential for making informed decisions about how to manage, protect, and sustain our planet and its natural resources. This EarthLabs module helps students understand their world as an interconnected living system. Students learn to identify the parts of the Earth system and the processes that connect them, starting locally and gradually expanding their view to regional and global scales.

Erin Bardar

409

Par Pond water balance  

International Nuclear Information System (INIS)

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

410

Distributed Selfish Load Balancing  

CERN Document Server

Suppose that a set of m tasks are to be shared as equally as possible amongst a set of n resources. A game-theoretic mechanism to find a suitable allocation is to associate each task with a ``selfish agent'', and require each agent to select a resource, with the cost of a resource being the number of agents to select it. Agents would then be expected to migrate from overloaded to underloaded resources, until the allocation becomes balanced. Recent work has studied the question of how this can take place within a distributed setting in which agents migrate selfishly without any centralized control. In this paper we discuss a natural protocol for the agents which combines the following desirable features: It can be implemented in a strongly distributed setting, uses no central control, and has good convergence properties. We show using a martingale technique that the process converges in expected time O(\\log\\log m + n^4). We also give a lower bound of \\Omega(\\max{\\log\\log m, n}) for the convergence time, as wel...

Berenbrink, P; Goldberg, L A; Goldberg, P; Hu, Z; Martin, R; Berenbrink, Petra; Friedetzky, Tom; Goldberg, Leslie Ann; Goldberg, Paul; Hu, Zengjian; Martin, Russell

2005-01-01

411

Interim balance: Ecology  

International Nuclear Information System (INIS)

Subjects: The ecology problem - world wide. Sectoral balances: The examples of energy, transportation, chemistry, agriculture and food industry, water supply. Destruction of nature and human discord. Conservatives in our political parties and their views on environmental protection. Alliance between reds and 'greens', integration between reds and greens. The Rhine initiative. Lead respects no borders, experiences of citizens' action groups in Lothringia and the Saar district. International airport Munich-II/comments by a protestant. 'Give priority to life'/A hearing on environmental protection. 4:96 - 'greens' in the Bremen Senate. Policy in a hard-hearing world/psychology of citizens' action groups. Critical ecological research and scientific establishment. Full productivity and ecology. The deluge to follow/Hints on how to build an ark. Symbiosis is more than coexistence/Ecologists' social theory. Throwing in two hundred elementary particles/on the way to an ecological concept of science. Scientific journals. Alternative literature. Teaching model for a teaching subject 'ecology'. (orig.)

412

Balanced Allocation on Graphs  

CERN Document Server

In this paper, we study the two choice balls and bins process when balls are not allowed to choose any two random bins, but only bins that are connected by an edge in an underlying graph. We show that for $n$ balls and $n$ bins, if the graph is almost regular with degree $n^\\epsilon$, where $\\epsilon$ is not too small, the previous bounds on the maximum load continue to hold. Precisely, the maximum load is $\\log \\log n + O(1/\\epsilon) + O(1)$. For general $\\Delta$-regular graphs, we show that the maximum load is $\\log\\log n + O(\\frac{\\log n}{\\log (\\Delta/\\log^4 n)}) + O(1)$ and also provide an almost matching lower bound of $\\log \\log n + \\frac{\\log n}{\\log (\\Delta \\log n)}$. V{\\"o}cking [Voc99] showed that the maximum bin size with $d$ choice load balancing can be further improved to $O(\\log\\log n /d)$ by breaking ties to the left. This requires $d$ random bin choices. We show that such bounds can be achieved by making only two random accesses and querying $d/2$ contiguous bins in each access. By grouping a ...

Kenthapadi, K

2005-01-01

413

Balancing "we" and "me".  

Science.gov (United States)

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

Congdon, Christine; Flynn, Donna; Redman, Melanie

2014-10-01

414

The right balance  

CERN Document Server

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

CERN Bulletin

2010-01-01

415

A question of balance: Kinetic balance for electrons and positrons  

International Nuclear Information System (INIS)

Graphical abstract: Kinetic balance for both electrons and positrons is achieved by applying the correct relation for positive and negative energy states separately and then using the electron and positron eigensolutions from the separate diagonalizations of the Hamiltonian as a dual basis. Highlights: ? Kinetic balance for electrons and positrons is achieved in a dual atomic basis. ? Dual atomic balance alleviates, but does not eliminate, energy prolapse. ? Positron affinities converge quicker with basis set size with dual atomic balance. - Abstract: The kinetic balance criterion used in current relativistic basis set codes is satisfied by the electron solutions of the Dirac equation, but not the positron solutions. A proposal for applying kinetic balance to both sets of solutions is presented. The method is applied along with “normal” kinetic balance to one-electron systems, to investigate its possible relation to prolapse, and to the positron affinity of F?, to investigate the kinetic energy deficiency for positron solutions. The new method reduces but does not eliminate prolapse for energy-optimized basis sets, and provides faster and smoother convergence with basis set size for the positron affinity.

416

Structural behaviour of YGa under high pressure  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-04-24

417

Sun-Earth Viewer  

Science.gov (United States)

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

418

Binary rare earth oxides  

CERN Document Server

Introduces the unique characteristics of the binary rare earth oxides with their chemistry, physics and applicationsProvides a comprehensive review of all the characteristics of rare earth oxides, essential for scientists and engineers involved with rare earths, oxides, inorganic materials, ceramics, and structures

Adachi, G; Kang, ZC

2006-01-01

419

Clouds and the Earth's Radiant Energy System  

Science.gov (United States)

The Clouds and the Earth's Radiant Energy System (CERES) instrument is one of five instruments that will be flown aboard the Tropical Rainfall Measuring Mission (TRMM) observatory. Data from the CERES instrument will be used to study the energy exchanged between the Sun and the Earth's atmosphere, surface and clouds, and space. This webpage describes the TRMM mission, the CERES insrument, and how Earth's daily weather and climate are controlled by the balance between the amount of solar energy received by the Earth (both by its surface and its atmosphere and clouds) and the amount of energy emitted by Earth into space. School children worldwide will be involved in the CERES program, enabling them to be part of a scientific project. As a CERES instrument passes over, students will make local observations to determine the types of clouds over their school, the clouds' altitudes and how much of the sky they cover. Via the Internet, the students will then place their data in the NASA Langley Distributed Active Archive Center where the data will be stored for further analysis by the CERES science team.

420

Pressure anisotropy in Jupiter's magnetodisc  

Science.gov (United States)

The magnetosphere-ionosphere coupling current system at Jupiter has been studied by a number of authors over the last decade. Until recently, however, the various modelling studies treated the magnetic field as an empirically-based input derived from Voyager observations. This limitation was removed by Nichols (2011), who employed a self-consistent field model calculated using force-balance between the outward plasma pressure gradients plus the centrifugal force of the rotating iogenic plasma, and the inward JxB force arising from the azimuthal current sheet. However, the above study, which incorporated the magnetic field model of Caudal (1983), employed isotropic plasma pressure, whereas it is known that anisotropic plasma pressure plays a key role in the stress balance at Jupiter (e.g. Paranicas et al., 1991). In this paper we generalise the computation to include anisotropic pressure, and compute the magnetic field by summing over elliptical integrals. We then calculate the magnetosphere-ionosphere coupling currents assuming an equatorial parallel-to-perpendicular pressure ratio of 1.14, the value determined by Paranicas et al. (1991), and we also consider the effect on the system of solar wind-induced compression events. We find that the anisotropy current dominates the current sheet in the middle magnetosphere between 20-40RJ, and that Jupiter's magnetosphere is susceptible to the firehose instability.

Nichols, J. D.; Achilleos, N.; Cowley, S. W. H.

2013-09-01

421

Empirical and Computational Pressure Drop Correlations for Pressurized Water Reactor Fuel Spacer Grids  

International Nuclear Information System (INIS)

Empirical and computational pressure drop correlations were developed to accurately estimate the pressure drop at the fuel spacer grid in a pressurized water reactor. The empirical correlation uses the balance of hydraulic forces acting on the spacer grid. The amount of pressure drop is assumed to depend largely on the reduction of the flow cross section, the flow constriction in the spacer region, and the frictional loss. The grid form drag due to the relative plugging and the flow constriction by the grid components were found to be the primary factors of the total pressure drop. The computational correlation combines the pressure drop due to flow blockage by the spacer grid and the pressure drop calculated by dynamics analysis. The pressure loss coefficients from the empirical correlation agree well with the measured ones for the spacer grids with and without the mixing vane. The computational correlation overpredicts the pressure loss coefficients for the spacer grid with the mixing vane

422

Balanced Cross Sections and Retrodeformation  

Science.gov (United States)

In this exercise, students investigate the use of balanced cross sections and retrodeformation to study faults that do not break the surface and their application to tectonics, folding, and earthquake hazards. Introductory materials explain how to construct geologic cross-sections, the idea of balance in a cross-section, and the concept of retrodeformability, whether or not the structures seen in a cross section can be 'undeformed' into their original positions. Using the Kink Method, students will construct a cross-section and test a balanced cross section to see if it is retrodeformable. Instructions, a blank cross section with data, study questions, and a bibliography are provided.

Pinter, Nicholas

423

Thermal balance testing of MSAT 2 spacecraft  

Science.gov (United States)

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

Samson, Serge; Choueiry, Elie

1994-01-01

424

Novel balance rehabilitation and training apparatus to improve functional balance  

Directory of Open Access Journals (Sweden)

Full Text Available A new balance rehabilitation and training apparatus has been developed to allow a balance-impaired person to cope with his or her fear of falling while safely and independently performing exercises necessary to improve functional balance. The apparatus consists of a stable platform where the user stands and a vertical structure that supports free-floating handles that the user holds with both hands while performing various exercises. The purpose of study 1 was to determine whether this new apparatus significantly alters the biological postural control system, and the purpose of study 2 was to document the benefits of balance training using the apparatus. Study 1 was a randomized repeated-measures design with six healthy adult subjects (mean age = 35.5 yr, and study 2 was a 4 wk intervention case study with a generally healthy 63-yr-old individual. The results suggest that postural sway characteristics and the cortical and proprioceptive feedback were not limi