Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyzer (TEGA)

NASA Technical Reports Server (NTRS)

Musselwhite, D. S.; Boynton, W. V.; Ming, Douglas W.; Quadlander, G.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

2000-01-01

Differential Scanning Calorimetry (DSC) combined with evolved gas analysis (EGA) is a well developed technique for the analysis of a wide variety of sample types with broad application in material and soil sciences. However, the use of the technique for samples under conditions of pressure and temperature as found on other planets is one of current C development and cutting edge research. The Thermal Evolved Gas Analyzer (MGA), which was designed, built and tested at the University of Arizona's Lunar and Planetary Lab (LPL), utilizes DSC/EGA. TEGA, which was sent to Mars on the ill-fated Mars Polar Lander, was to be the first application of DSC/EGA on the surface of Mars as well as the first direct measurement of the volatile-bearing mineralogy in martian soil.

Approach to thermal equilibrium in atomic collisions.

PubMed

Zhang, P; Kharchenko, V; Dalgarno, A; Matsumi, Y; Nakayama, T; Takahashi, K

2008-03-14

The energy relaxation of fast atoms moving in a thermal bath gas is explored experimentally and theoretically. Two time scales characterize the equilibration, one a short time, in which the isotropic energy distribution profile relaxes to a Maxwellian shape at some intermediate effective temperature, and the second, a longer time in which the relaxation preserves a Maxwellian distribution and its effective temperature decreases continuously to the bath gas temperature. The formation and preservation of a Maxwellian distribution does not depend on the projectile to bath gas atom mass ratio. This two-stage behavior arises due to the dominance of small angle scattering and small energy transfer in the collisions of neutral particles. Measurements of the evolving Doppler profiles of emission from excited initially energetic nitrogen atoms traversing bath gases of helium and argon confirm the theoretical predictions.

Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyser (TEGA)

NASA Technical Reports Server (NTRS)

Musselwhite, D. S.; Boynton, W. V.; Ming, D. W.; Quadlander, G.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

2000-01-01

Differential Scanning Calorimetry (DSC) combined with evolved gas analysis (EGA) is a well developed technique for the analysis of a wide variety of sample types with broad application in material and soil sciences. However, the use of the technique for samples under conditions of pressure and temperature as found on other planets is one of current development and cutting edge research. The Thermal Evolved Gas Analyzer (TEGA), which was designed, built and tested at the University of Arizona's Lunar and Planetary Lab (LPL), utilizes DSC/EGA. TEGA, which was sent to Mars on the ill-fated Mars Polar Lander, was to be the first application of DSC/EGA on the surface of Mars as well as the first direct measurement of the volatile-bearing mineralogy in martian soil. Additional information is available in the original extended abstract.

On-line gas chromatographic analysis of airborne particles

DOEpatents

Hering, Susanne V [Berkeley, CA; Goldstein, Allen H [Orinda, CA

2012-01-03

A method and apparatus for the in-situ, chemical analysis of an aerosol. The method may include the steps of: collecting an aerosol; thermally desorbing the aerosol into a carrier gas to provide desorbed aerosol material; transporting the desorbed aerosol material onto the head of a gas chromatography column; analyzing the aerosol material using a gas chromatograph, and quantizing the aerosol material as it evolves from the gas chromatography column. The apparatus includes a collection and thermal desorption cell, a gas chromatograph including a gas chromatography column, heated transport lines coupling the cell and the column; and a quantization detector for aerosol material evolving from the gas chromatography column.

Thermal and Evolved Gas Analysis of Geologic Samples Containing Organic Materials: Implications for the 2007 Mars Phoenix Scout Mission

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Ming, Douglas W.; Golden, D. C.; Boynton, W. V.

2006-01-01

The Thermal and Evolved Gas Analyzer (TEGA) instrument scheduled to fly onboard the 2007 Mars Phoenix Scout Mission will perform differential scanning calorimetry (DSC) and evolved gas analysis (EGA) of soil samples and ice collected from the surface and subsurface at a northern landing site on Mars. We have been developing a sample characterization data library using a laboratory DSC integrated with a quadrupole mass spectrometer to support the interpretations of TEGA data returned during the mission. The laboratory TEGA test-bed instrument has been modified to operate under conditions similar to TEGA, i.e., reduced pressure (e.g., 100 torr) and reduced carrier gas flow rates. We have previously developed a TEGA data library for a variety of volatile-bearing mineral phases, including Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates. Here we examine the thermal and evolved gas properties of samples that contain organics. One of the primary objectives of the Phoenix Scout Mission is to search for habitable zones by assessing organic or biologically interesting materials in icy soil. Nitrogen is currently the carrier gas that will be used for TEGA. In this study, we examine two possible modes of detecting organics in geologic samples; i.e., pyrolysis using N2 as the carrier gas and combustion using O2 as the carrier gas.

Differential Scanning Calorimetry and Evolved Gas Analysis at Mars Ambient Conditions Using the Thermal Evolved Gas Analyser (TEGA)

NASA Technical Reports Server (NTRS)

Musselwhite, D. S.; Boynton, W. V.; Ming, D. W.; Quadlander, G. A.; Kerry, K. E.; Bode, R. C.; Bailey, S. H.; Ward, M. G.; Pathare, A. V.; Lorenz, R. D.

2000-01-01

We are conducting DSC/EGA experiments at Mars ambient temperature and pressure using the TEGA engineering model. These tests illustrate the outstanding capabilities of a TEGA-like instrument on the surface of Mars.

Massive Black Hole Mergers: Can we see what LISA will hear?

NASA Technical Reports Server (NTRS)

Centrella, Joan

2009-01-01

Coalescing massive black hole binaries are formed when galaxies merge. The final stages of this coalescence produce strong gravitational wave signals that can be detected by the space-borne LISA. When the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a first step towards this problem by mapping the flow of pressureless matter in the dynamic, 3-D general relativistic spacetime around the merging black holes. We report on the results of these initial simulations and discuss their likely importance for future hydrodynamical simulations.

Hydroxylammonium Nitrate Compatibility Tests with Various Materials - A Liquid Propellant Study

DTIC Science & Technology

1990-07-01

evolved gas was determined by gas analysis. The propellant off-loaded from the test tube was analyzed for leached metals (if the material was a...HAN Solution 15 - The amount of gas evolved during the 30-day observation period was calculated from the ullage volume of the flask, the pressure read...much volume and was ignored. The length of the U-gauge was 34 cm from top to bottom of the U. The full scale range was 300 mm Hg corresponding to a gas

Human-polar bear interactions in a changing Arctic: Existing and emerging concerns

USGS Publications Warehouse

Atwood, Todd C.; Simac, Kristin; Breck, Stewart; York, Geoff; Wilder, James

2017-01-01

The behavior and sociality of polar bears (Ursus maritimus) have been shaped by evolved preferences for sea ice habitat and preying on marine mammals. However, human behavior is causing changes to the Arctic marine ecosystem through the influence of greenhouse gas emissions that drive long-term change in ecosystem processes and via the presence of in situ stressors associated with increasing human activities. These changes are making it more difficult for polar bears to reliably use their traditional habitats and maintain fitness. Here, we provide an overview of how human activities in the Arctic are likely to change a polar bear’s behavior and to influence their resilience to environmental change. Developing a more thorough understanding of polar bear behavior and their capacity for flexibility in response to anthropogenic disturbances and subsequent mitigations may lead to successful near-term management interventions.

Thermal and Evolved Gas Analysis of "Nanophase" Carbonates: Implications for Thermal and Evolved Gas Analysis on Mars Missions

NASA Technical Reports Server (NTRS)

Lauer, Howard V., Jr.; Archer, P. D., Jr.; Sutter, B.; Niles, P. B.; Ming, Douglas W.

2012-01-01

Data collected by the Mars Phoenix Lander's Thermal and Evolved Gas Analyzer (TEGA) suggested the presence of calcium-rich carbonates as indicated by a high temperature CO2 release while a low temperature (approx.400-680 C) CO2 release suggested possible Mg- and/or Fe-carbonates [1,2]. Interpretations of the data collected by Mars remote instruments is done by comparing the mission data to a database on the thermal properties of well-characterized Martian analog materials collected under reduced and Earth ambient pressures [3,4]. We are proposing that "nano-phase" carbonates may also be contributing to the low temperature CO2 release. The objectives of this paper is to (1) characterize the thermal and evolved gas proper-ties of carbonates of varying particle size, (2) evaluate the CO2 releases from CO2 treated CaO samples and (3) examine the secondary CO2 release from reheated calcite of varying particle size.

Stellar physics. Observing the onset of outflow collimation in a massive protostar.

PubMed

Carrasco-González, C; Torrelles, J M; Cantó, J; Curiel, S; Surcis, G; Vlemmings, W H T; van Langevelde, H J; Goddi, C; Anglada, G; Kim, S-W; Kim, J-S; Gómez, J F

2015-04-03

The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic ionized wind whose morphology evolves as it moves within a toroidal density stratification. Copyright © 2015, American Association for the Advancement of Science.

Thermal and Evolved Gas Analysis of Hydromagnesite and Nesquehonite: Implications for Remote Thermal Analysis on Mars

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Ming, D. W.; Golden, D. C.; Lin, I.-C.; Boynton, W. V.

2000-01-01

Volatile-bearing minerals (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates) may be important phases on the surface of Mars. In order to characterize these potential phases the Thermal Evolved-Gas Analyzer (TEGA), which was onboard the Mars Polar Lander, was to have performed differential scanning calorimetry (DSC) and evolved-gas analysis of soil samples collected from the surface. The sample chamber in TEGA operates at about 100 mbar (approximately 76 torr) with a N2, carrier gas flow of 0.4 seem. Essentially, no information exists on the effects of reduced pressure on the thermal properties of volatile-bearing minerals. In support of TEGA, we have constructed a laboratory analog for TEGA from commercial instrumentation. We connected together a commercial differential scanning calorimeter, a quadruple mass spectrometer, a vacuum pump, digital pressure gauge, electronic mass flow meter, gas "K" bottles, gas dryers, and high and low pressure regulators using a collection of shut off and needle valves. Our arrangement allows us to vary and control the pressure and carrier gas flow rate inside the calorimeter oven chamber.

Multiple Approaches to Characterizing Nano-Pore Structure of Barnett Shale

NASA Astrophysics Data System (ADS)

Hu, Q.; Gao, Z.; Ewing, R. P.; Dultz, S.; Kaufmann, J.; Hamamoto, S.; Webber, B.; Ding, M.

2013-12-01

Microscopic characteristics of porous media - pore shape, pore-size distribution, and pore connectivity - control fluid flow and mass transport. This presentation discusses various approaches to investigating nano-pore structure of Barnett shale, with its implications in gas production behavior. The innovative approaches include imbibition, tracer diffusion, edge-accessible porosity, porosimetry (mercury intrusion porosimetry, nitrogen and water vapor sorption isotherms, and nuclear magnetic resonance cyroporometry), and imaging (Wood's metal impregnation followed with laser ablation-inductively coupled plasma-mass spectrometry, focused ion beam/scanning electron microscopy, and small angle neutron scattering). Results show that the shale pores are predominantly in the nm size range, with measured median pore-throat diameters about 5 nm. But small pore size is not the major contributor to low gas recovery; rather, the low mass diffusivity appears to be caused by low pore connectivity of Barnett shale. Chemical diffusion in sparsely-connected pore spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition and diffusion tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the nano-pore structure characteristics of shales and other natural rocks.

Flame retardancy and thermal behavior of intumescent flame-retardant EVA composites with an efficient triazine-based charring agent

NASA Astrophysics Data System (ADS)

Xu, Bo; Ma, Wen; Wu, Xiao; Qian, Lijun; Jiang, Shan

2018-04-01

Intumescent flame retardant (IFR) EVA composites were prepared based on a hyperbranched triazine charring-foaming agent (HTCFA) and ammonium polyphosphate (APP). The synergistic effect of HTCFA and APP on the flame retardancy and thermal behavior of the composites were investigated through flammability tests, cone calorimeter measurements, thermogravimetric analysis (TGA) including evolved gas analysis (TG-IR) and residue analysis (Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), x-ray Photoelectron Spectroscopy (XPS) and scanning electron microscopy (SEM)). The flammability test results showed HTCFA/APP (1/3) system presented the best synergistic effect in flame-retardant EVA composites with the highest LOI value and UL-94 V-0 rating. As for cone calorimeter results, IFR changed the combustion behavior of EVA and resulted in remarkable decrease of flammability and smoke product. TGA results showed the synergistic effect between APP and HTCFA could strengthen the char-forming ability of composites. TG-IR results indicated the melt viscosities and gas release with increasing temperature were well-correlated for EVA/IFR composite. The residue analysis results from SEM, LRS, FT-IR and XPS revealed IFR promoted forming more compact graphitic char layer, connected by rich P–O–C and P–N structures.

Modeling Flows Around Merging Black Hole Binaries

NASA Technical Reports Server (NTRS)

Centrella, Joan

2008-01-01

Coalescing massive black hole binaries are produced by the merger of galaxies. The final stages of the black hole coalescence produce strong gravitational radiation that can be detected by the space-borne LISA. In cases in which the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a first step towards this problem by mapping the flow of pressureless matter in the dynamic, 3-D general relativistic spacetime around the merging black holes. We report on the results of these initial simulations and discuss their likely importance for future hydrodynamical simulations.

Coupling experimental data and a prototype model to probe the physical and chemical processes of 2,4-dinitroimidazole solid-phase thermal decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behrens, R.; Minier, L.; Bulusu, S.

1998-12-31

The time-dependent, solid-phase thermal decomposition behavior of 2,4-dinitroimidazole (2,4-DNI) has been measured utilizing simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) methods. The decomposition products consist of gaseous and non-volatile polymeric products. The temporal behavior of the gas formation rates of the identified products indicate that the overall thermal decomposition process is complex. In isothermal experiments with 2,4-DNI in the solid phase, four distinguishing features are observed: (1) elevated rates of gas formation are observed during the early stages of the decomposition, which appear to be correlated to the presence of exogenous water in the sample; (2) this is followed bymore » a period of relatively constant rates of gas formation; (3) next, the rates of gas formation accelerate, characteristic of an autocatalytic reaction; (4) finally, the 2,4-DNI is depleted and gaseous decomposition products continue to evolve at a decreasing rate. A physicochemical and mathematical model of the decomposition of 2,4-DNI has been developed and applied to the experimental results. The first generation of this model is described in this paper. Differences between the first generation of the model and the experimental data collected under different conditions suggest refinements for the next generation of the model.« less

A physical description of fission product behavior fuels for advanced power reactors.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaganas, G.; Rest, J.; Nuclear Engineering Division

2007-10-18

The Global Nuclear Energy Partnership (GNEP) is considering a list of reactors and nuclear fuels as part of its chartered initiative. Because many of the candidate materials have not been explored experimentally under the conditions of interest, and in order to economize on program costs, analytical support in the form of combined first principle and mechanistic modeling is highly desirable. The present work is a compilation of mechanistic models developed in order to describe the fission product behavior of irradiated nuclear fuel. The mechanistic nature of the model development allows for the possibility of describing a range of nuclear fuelsmore » under varying operating conditions. Key sources include the FASTGRASS code with an application to UO{sub 2} power reactor fuel and the Dispersion Analysis Research Tool (DART ) with an application to uranium-silicide and uranium-molybdenum research reactor fuel. Described behavior mechanisms are divided into subdivisions treating fundamental materials processes under normal operation as well as the effect of transient heating conditions on these processes. Model topics discussed include intra- and intergranular gas-atom and bubble diffusion, bubble nucleation and growth, gas-atom re-solution, fuel swelling and ?scion gas release. In addition, the effect of an evolving microstructure on these processes (e.g., irradiation-induced recrystallization) is considered. The uranium-alloy fuel, U-xPu-Zr, is investigated and behavior mechanisms are proposed for swelling in the {alpha}-, intermediate- and {gamma}-uranium zones of this fuel. The work reviews the FASTGRASS kinetic/mechanistic description of volatile ?scion products and, separately, the basis for the DART calculation of bubble behavior in amorphous fuels. Development areas and applications for physical nuclear fuel models are identified.« less

Kinetics and evolved gas analysis for pyrolysis of food processing wastes using TGA/MS/FT-IR.

PubMed

Özsin, Gamzenur; Pütün, Ayşe Eren

2017-06-01

The objective of this study was to identify the pyrolysis of different bio-waste produced by food processing industry in a comprehensible manner. For this purpose, pyrolysis behaviors of chestnut shells (CNS), cherry stones (CS) and grape seeds (GS) were investigated by thermogravimetric analysis (TGA) combined with a Fourier-transform infrared (FT-IR) spectrometer and a mass spectrometer (MS). In order to make available theoretical groundwork for biomass pyrolysis, activation energies were calculated with the help of four different model-free kinetic methods. The results are attributed to the complex reaction schemes which imply parallel, competitive and complex reactions during pyrolysis. During pyrolysis, the evolution of volatiles was also characterized by FT-IR and MS. The main evolved gases were determined as H 2 O, CO 2 and hydrocarbons such as CH 4 and temperature dependent profiles of the species were obtained. Copyright © 2017 Elsevier Ltd. All rights reserved.

Carbon dioxide capture from a cement manufacturing process

DOEpatents

Blount, Gerald C [North Augusta, SC; Falta, Ronald W [Seneca, SC; Siddall, Alvin A [Aiken, SC

2011-07-12

A process of manufacturing cement clinker is provided in which a clean supply of CO.sub.2 gas may be captured. The process also involves using an open loop conversion of CaO/MgO from a calciner to capture CO.sub.2 from combustion flue gases thereby forming CaCO.sub.3/CaMg(CO.sub.3).sub.2. The CaCO.sub.3/CaMg(CO.sub.3).sub.2 is then returned to the calciner where CO.sub.2 gas is evolved. The evolved CO.sub.2 gas, along with other evolved CO.sub.2 gases from the calciner are removed from the calciner. The reactants (CaO/MgO) are feed to a high temperature calciner for control of the clinker production composition.

Summary of Results from the Mars Phoenix Lander's Thermal Evolved Gas Analyzer

NASA Technical Reports Server (NTRS)

Sutter, B.; Ming, D. W.; Boynton, W. V.; Niles, P. B.; Hoffman, J.; Lauer, H. V.; Golden, D. C.

2009-01-01

The Mars Phoenix Scout Mission with its diverse instrument suite successfully examined several soils on the Northern plains of Mars. The Thermal and Evolved Gas Analyzer (TEGA) was employed to detect evolved volatiles and organic and inorganic materials by coupling a differential scanning calorimeter (DSC) with a magnetic-sector mass spectrometer (MS) that can detect masses in the 2 to 140 dalton range [1]. Five Martian soils were individually heated to 1000 C in the DSC ovens where evolved gases from mineral decompostion products were examined with the MS. TEGA s DSC has the capability to detect endothermic and exothermic reactions during heating that are characteristic of minerals present in the Martian soil.

A Case Study of the De Novo Evolution of a Complex Odometric Behavior in Digital Organisms

PubMed Central

Grabowski, Laura M.; Bryson, David M.; Dyer, Fred C.; Pennock, Robert T.; Ofria, Charles

2013-01-01

Investigating the evolution of animal behavior is difficult. The fossil record leaves few clues that would allow us to recapitulate the path that evolution took to build a complex behavior, and the large population sizes and long time scales required prevent us from re-evolving such behaviors in a laboratory setting. We present results of a study in which digital organisms–self-replicating computer programs that are subject to mutations and selection–evolved in different environments that required information about past experience for fitness-enhancing behavioral decisions. One population evolved a mechanism for step-counting, a surprisingly complex odometric behavior that was only indirectly related to enhancing fitness. We examine in detail the operation of the evolved mechanism and the evolutionary transitions that produced this striking example of a complex behavior. PMID:23577113

Melter feed viscosity during conversion to glass: Comparison between low-activity waste and high-level waste feeds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Tongan; Chun, Jaehun; Dixon, Derek R.

During nuclear waste vitrification, a melter feed (generally a slurry-like mixture of a nuclear waste and various glass forming and modifying additives) is charged into the melter where undissolved refractory constituents are suspended together with evolved gas bubbles from complex reactions. Knowledge of flow properties of various reacting melter feeds is necessary to understand their unique feed-to-glass conversion processes occurring within a floating layer of melter feed called a cold cap. The viscosity of two low-activity waste (LAW) melter feeds were studied during heating and correlated with volume fractions of undissolved solid phase and gas phase. In contrast to themore » high-level waste (HLW) melter feed, the effects of undissolved solid and gas phases play comparable roles and are required to represent the viscosity of LAW melter feeds. This study can help bring physical insights to feed viscosity of reacting melter feeds with different compositions and foaming behavior in nuclear waste vitrification.« less

Numerical analysis of pressure and porosity evolution in lava domes during periodic degassing conditions

NASA Astrophysics Data System (ADS)

Hyman, D.; Bursik, M. I.; Pitman, E. B.

2017-12-01

The collapse or explosive breakup of growing and degassing lava domes presents a significant hazard due to the generation of dense, mobile pyroclastic flows as well as the wide dispersal of dense ballistic blocks. Lava dome stability is in large part governed by the balance of transport and storage of gas within the pore space. Because pore pressurization reduces the effective stress within a dome, the transient distribution of elevated gas pressure is critically important to understanding dome break up. We combine mathematical and numerical analyses to gain a better understanding of the temporal variation in gas flow and storage within the dome system. In doing so, we develop and analyze new governing equations describing nonlinear gas pressure diffusion in a deforming dome with an evolving porosity field. By relating porosity, permeability, and pressure, we show that the flux of gas through a dome is highly sensitive to the porosity distribution and viscosity of the lava, as well as the timescale and magnitude of the gas supply. The numerical results suggest that the diffusion of pressure and porosity variations play an integral role in the cyclic growth and destruction of small domes.The nearly continuous cycles of lava dome growth, pressurization, and failure that have characterized the last two decades of eruptive history at Volcán Popocatépetl, Mexico provide excellent natural data with which to compare new models of transient dome pressurization. At Popocatépetl, periodic pressure increases brought on by changes in gas supply into the base of the dome may play a role in its cyclic growth and destruction behavior. We compare our model of cyclic pressurization with lava dome survival data from Popocatépetl. We show that transient changes in pore pressure explain how small lava domes evolve to a state of criticality before explosion or collapse. Additionally, numerical analyses presented here suggest that short-term oscillations cannot arise within the dome, and must be the result of an oscillating supply of gas into the dome. The oscillating gas supply may result from alternating gas-rich and gas-poor regions of rising magma, so-called "porosity waves" within the conduit. These internal pressure fluctuations lead to periodic reductions in the stress required to fracture the dome and induce explosion.

Evolving mobile robots able to display collective behaviors.

PubMed

Baldassarre, Gianluca; Nolfi, Stefano; Parisi, Domenico

2003-01-01

We present a set of experiments in which simulated robots are evolved for the ability to aggregate and move together toward a light target. By developing and using quantitative indexes that capture the structural properties of the emerged formations, we show that evolved individuals display interesting behavioral patterns in which groups of robots act as a single unit. Moreover, evolved groups of robots with identical controllers display primitive forms of situated specialization and play different behavioral functions within the group according to the circumstances. Overall, the results presented in the article demonstrate that evolutionary techniques, by exploiting the self-organizing behavioral properties that emerge from the interactions between the robots and between the robots and the environment, are a powerful method for synthesizing collective behavior.

Near-limit flame structures at low Lewis number

NASA Technical Reports Server (NTRS)

Ronney, Paul D.

1990-01-01

The characteristics of premixed gas flames in mixtures with low Lewis numbers near flammability limits were studied experimentally using a low-gravity environment to reduce buoyant convection. The behavior of such flames was found to be dominated by diffusive-thermal instabilities. For sufficiently reactive mixtures, cellular structures resulting from these instabilities were observed and found to spawn new cells in regular patterns. For less reactive mixtures, cells formed shortly after ignition but did not spawn new cells; instead these cells evolved into a flame structure composed of stationary, apparently stable spherical flamelets. Experimental observations are found to be in qualitative agreement with elementary analytical models based on the interaction of heat release due to chemical reaction, differential diffusion of thermal energy and mass, flame front curvature, and volumetric heat losses due to gas and/or soot radiation.

Container and method for absorbing and reducing hydrogen concentration

DOEpatents

Wicks, George G.; Lee, Myung W.; Heung, Leung K.

2001-01-01

A method for absorbing hydrogen from an enclosed environment comprising providing a vessel; providing a hydrogen storage composition in communication with a vessel, the hydrogen storage composition further comprising a matrix defining a pore size which permits the passage of hydrogen gas while blocking the passage of gaseous poisons; placing a material within the vessel, the material evolving hydrogen gas; sealing the vessel; and absorbing the hydrogen gas released into the vessel by the hydrogen storage composition. A container for absorbing evolved hydrogen gas comprising: a vessel having an interior and adapted for receiving materials which release hydrogen gas; a hydrogen absorbing composition in communication with the interior, the composition defining a matrix surrounding a hydrogen absorber, the matrix permitting the passage of hydrogen gas while excluding gaseous poisons; wherein, when the vessel is sealed, hydrogen gas, which is released into the vessel interior, is absorbed by the hydrogen absorbing composition.

Measurement of fuel corrosion products using planar laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Wantuck, Paul J.; Sappey, Andrew D.; Butt, Darryl P.

1993-01-01

Characterizing the corrosion behavior of nuclear fuel material in a high-temperature hydrogen environment is critical for ascertaining the operational performance of proposed nuclear thermal propulsion (NTP) concepts. In this paper, we describe an experimental study undertaken to develop and test non-intrusive, laser-based diagnostics for ultimately measuring the distribution of key gas-phase corrosion products expected to evolve during the exposure of NTP fuel to hydrogen. A laser ablation technique is used to produce high temperature, vapor plumes from uranium-free zirconium carbide (ZrC) and niobium carbide (NbC) forms for probing by various optical diagnostics including planar laser-induced fluorescence (PLIF). We discuss the laser ablation technique, results of plume emission measurements, and we describe both the actual and proposed planar LIF schemes for imaging constituents of the ablated ZrC and NbC plumes. Envisioned testing of the laser technique in rf-heated, high temperature gas streams is also discussed.

Application of modern online instrumentation for chemical analysis of gas and particulate phases of exhaust at the European Commission heavy-duty vehicle emission laboratory.

PubMed

Adam, T W; Chirico, R; Clairotte, M; Elsasser, M; Manfredi, U; Martini, G; Sklorz, M; Streibel, T; Heringa, M F; Decarlo, P F; Baltensperger, U; De Santi, G; Krasenbrink, A; Zimmermann, R; Prevot, A S H; Astorga, C

2011-01-01

The European Commission recently established a novel test facility for heavy-duty vehicles to enhance more sustainable transport. The facility enables the study of energy efficiency of various fuels/scenarios as well as the chemical composition of evolved exhaust emissions. Sophisticated instrumentation for real-time analysis of the gas and particulate phases of exhaust has been implemented. Thereby, gas-phase characterization was carried out by a Fourier transform infrared spectrometer (FT-IR; carbonyls, nitrogen-containing species, small hydrocarbons) and a resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI-TOFMS; monocyclic and polycyclic aromatic hydrocarbons). For analysis of the particulate phase, a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS; organic matter, chloride, nitrate), a condensation particle counter (CPC; particle number), and a multiangle absorption photometer (MAAP; black carbon) were applied. In this paper, the first application of the new facility in combination with the described instruments is presented, whereby a medium-size truck was investigated by applying different driving cycles. The goal was simultaneous chemical characterization of a great variety of gaseous compounds and particulate matter in exhaust on a real-time basis. The time-resolved data allowed new approaches to view the results; for example, emission factors were normalized to time-resolved consumption of fuel and were related to emission factors evolved during high speeds. Compounds could be identified that followed the fuel consumption, others showed very different behavior. In particular, engine cold start, engine ignition (unburned fuel), and high-speed events resulted in unique emission patterns.

A new evolutionary system for evolving artificial neural networks.

PubMed

Yao, X; Liu, Y

1997-01-01

This paper presents a new evolutionary system, i.e., EPNet, for evolving artificial neural networks (ANNs). The evolutionary algorithm used in EPNet is based on Fogel's evolutionary programming (EP). Unlike most previous studies on evolving ANN's, this paper puts its emphasis on evolving ANN's behaviors. Five mutation operators proposed in EPNet reflect such an emphasis on evolving behaviors. Close behavioral links between parents and their offspring are maintained by various mutations, such as partial training and node splitting. EPNet evolves ANN's architectures and connection weights (including biases) simultaneously in order to reduce the noise in fitness evaluation. The parsimony of evolved ANN's is encouraged by preferring node/connection deletion to addition. EPNet has been tested on a number of benchmark problems in machine learning and ANNs, such as the parity problem, the medical diagnosis problems, the Australian credit card assessment problem, and the Mackey-Glass time series prediction problem. The experimental results show that EPNet can produce very compact ANNs with good generalization ability in comparison with other algorithms.

Navier-Stokes hydrodynamics of thermal collapse in a freely cooling granular gas.

PubMed

Kolvin, Itamar; Livne, Eli; Meerson, Baruch

2010-08-01

We show that, in dimension higher than one, heat diffusion and viscosity cannot arrest thermal collapse in a freely evolving dilute granular gas, even in the absence of gravity. Thermal collapse involves a finite-time blowup of the gas density. It was predicted earlier in ideal, Euler hydrodynamics of dilute granular gases in the absence of gravity, and in nonideal, Navier-Stokes granular hydrodynamics in the presence of gravity. We determine, analytically and numerically, the dynamic scaling laws that characterize the gas flow close to collapse. We also investigate bifurcations of a freely evolving dilute granular gas in circular and wedge-shaped containers. Our results imply that, in general, thermal collapse can only be arrested when the gas density becomes comparable with the close-packing density of grains. This provides a natural explanation to the formation of densely packed clusters of particles in a variety of initially dilute granular flows.

Insights into the Sulfur Mineralogy of Martian Soil at Rocknest, Gale Crater, Enabled by Evolved Gas Analyses

NASA Technical Reports Server (NTRS)

McAdam, A.; Franz, H.; Archer, P., Jr.; Freissinet, C.; Sutter, B.; Glavin, D.; Eigenbrode, J.; Bower, H.; Stern, J.; Mchaffy, P.;

Thermal and Evolved Gas Behavior of Calcite Under Mars Phoenix TEGA Operating Conditions

NASA Technical Reports Server (NTRS)

Ming, D.W.; Niles, P.B.; Morris, R.V.; Boynton, W.V.; Golden, D.C.; Lauer, H.V.; Sutter, B.

2009-01-01

The Mars Phoenix Scout Mission with its diverse instrument suite successfully examined several soils on the Northern plains of Mars. The Thermal and Evolved Gas Analyzer (TEGA) was employed to detect organic and inorganic materials by coupling a differential scanning calorimeter (DSC) with a magnetic-sector mass spectrometer (MS). Martian soil was heated up to 1000 C in the DSC ovens and evolved gases from mineral decomposition products were examined with the MS. TEGA s DSC has the capability to detect endothermic and exothermic reactions during heating that are characteristic of minerals present in the Martian soil. Initial TEGA results indicated the presence of endothermic peaks with onset temperatures that ranged from 675 C to 750 C with corresponding CO2 release. This result suggests the presence of calcite (CaCO3. CaO + CO2). Organic combustion to CO2 is not likely since this mostly occurs at temperatures below 550 C. Fe-carbonate and Mg-carbonate are not likely because their decomposition temperatures are less than 600 C. TEGA enthalpy determinations suggest that calcite, may occur in the Martian soil in concentrations of approx.1 to 5 wt. %. The detection of calcite could be questioned based on previous results that suggest Mars soils are mostly acidic. However, the Phoenix landing site soil pH was measured at pH 8.3 0.5, which is typical of terrestrial soils where pH is controlled by calcite solubility. The range of onset temperatures and calcite concentration as calculated by TEGA is poorly con-strained in part because of limited thermal data of cal-cite at reduced pressures. TEGA operates at <30 mbar while most calcite literature thermal data was obtained at 1000 mbar or higher pressures.

Self-organization of intertidal snails facilitates evolution of aggregation behavior.

PubMed

Stafford, Richard; Davies, Mark S; Williams, Gray A

2008-01-01

Many intertidal snails form aggregations during emersion to minimize desiccation stress. Here we investigate possible mechanisms for the evolution of such behavior. Two behavioral traits (following of mucus trails, and crevice occupation), which both provide selective advantages to individuals that possess the traits over individuals that do not, result in self-organization of aggregations in crevices in the rock surface. We suggest that the existence of self-organizing aggregations provides a mechanism by which aggregation behavior can evolve. The inclusion of an explicitly coded third behavior, aggregation, in a simulated population produces patterns statistically similar to those found on real rocky shores. Allowing these three behaviors to evolve using an evolutionary algorithm, however, results in aggregation behavior being selected against on shores with high crevice density. The inclusion of broadcast spawning dispersal mechanisms in the simulation, however, results in aggregation behavior evolving as predicted on shores with both high crevice density and low crevice density (evolving in crevices first, and then both in crevices and on flat rock), indicating the importance of environmental interactions in understanding evolutionary processes. We propose that self-organization can be an important factor in the evolution of group behaviors.

Impact-induced devolatilization and hydrogen isotopic fractionation of serpentine: Implications for planetary accretion

NASA Technical Reports Server (NTRS)

Tyburczy, James A.; Krishnamurthy, R. V.; Epstein, Samuel; Ahrens, Thomas J.

1988-01-01

Impact-induced devolatilization of porous serpentine was investigated using two independent experimental methods, the gas recovery and the solid recovery method, each yielding nearly identical results. For shock pressures near incipient devolatilization, the hydrogen isotopic composition of the evolved H2O is very close to that of the starting material. For shock pressures at which up to 12 percent impact-induced devolatilization occurs, the bulk evolved gas is significantly lower in deuterium than the starting material. There is also significant reduction of H2O to H2 in gases recovered at these higher shock pressures, probably caused by reaction of evolved H2O with the metal gas recovery fixture. Gaseous H2O-H2 isotopic fractionation suggests high temperature isotopic equilibrium between the gaseous species, indicating initiation of devolatilization at sites of greater than average energy deposition. Bulk gas-residual solid isotopic fractionations indicate nonequilibrium, kinetic control of gas-solid isotopic ratios. Impact-induced hydrogen isotopic fractionation of hydrous silicates during accretion can strongly affect the long-term planetary isotopic ratios of planetary bodies, leaving the interiors enriched in deuterium. Depending on the model used for extrapolation of the isotopic fractionation to devolatilization fractions greater than those investigated experimentally can result from this process.

Self-organizing network services with evolutionary adaptation.

PubMed

Nakano, Tadashi; Suda, Tatsuya

2005-09-01

This paper proposes a novel framework for developing adaptive and scalable network services. In the proposed framework, a network service is implemented as a group of autonomous agents that interact in the network environment. Agents in the proposed framework are autonomous and capable of simple behaviors (e.g., replication, migration, and death). In this paper, an evolutionary adaptation mechanism is designed using genetic algorithms (GAs) for agents to evolve their behaviors and improve their fitness values (e.g., response time to a service request) to the environment. The proposed framework is evaluated through simulations, and the simulation results demonstrate the ability of autonomous agents to adapt to the network environment. The proposed framework may be suitable for disseminating network services in dynamic and large-scale networks where a large number of data and services need to be replicated, moved, and deleted in a decentralized manner.

Modeling Temporal Behavior in Large Networks: A Dynamic Mixed-Membership Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossi, R; Gallagher, B; Neville, J

Given a large time-evolving network, how can we model and characterize the temporal behaviors of individual nodes (and network states)? How can we model the behavioral transition patterns of nodes? We propose a temporal behavior model that captures the 'roles' of nodes in the graph and how they evolve over time. The proposed dynamic behavioral mixed-membership model (DBMM) is scalable, fully automatic (no user-defined parameters), non-parametric/data-driven (no specific functional form or parameterization), interpretable (identifies explainable patterns), and flexible (applicable to dynamic and streaming networks). Moreover, the interpretable behavioral roles are generalizable, computationally efficient, and natively supports attributes. We applied ourmore » model for (a) identifying patterns and trends of nodes and network states based on the temporal behavior, (b) predicting future structural changes, and (c) detecting unusual temporal behavior transitions. We use eight large real-world datasets from different time-evolving settings (dynamic and streaming). In particular, we model the evolving mixed-memberships and the corresponding behavioral transitions of Twitter, Facebook, IP-Traces, Email (University), Internet AS, Enron, Reality, and IMDB. The experiments demonstrate the scalability, flexibility, and effectiveness of our model for identifying interesting patterns, detecting unusual structural transitions, and predicting the future structural changes of the network and individual nodes.« less

Storytelling, behavior planning, and language evolution in context.

PubMed

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes.

Storytelling, behavior planning, and language evolution in context

PubMed Central

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes. PMID:25360123

A Direct Numerical Simulation of a Temporally Evolving Liquid-Gas Turbulent Mixing Layer

NASA Astrophysics Data System (ADS)

Vu, Lam Xuan; Chiodi, Robert; Desjardins, Olivier

2017-11-01

Air-blast atomization occurs when streams of co-flowing high speed gas and low speed liquid shear to form drops. Air-blast atomization has numerous industrial applications from combustion engines in jets to sprays used for medical coatings. The high Reynolds number and dynamic pressure ratio of a realistic air-blast atomization case requires large eddy simulation and the use of multiphase sub-grid scale (SGS) models. A direct numerical simulations (DNS) of a temporally evolving mixing layer is presented to be used as a base case from which future multiphase SGS models can be developed. To construct the liquid-gas mixing layer, half of a channel flow from Kim et al. (JFM, 1987) is placed on top of a static liquid layer that then evolves over time. The DNS is performed using a conservative finite volume incompressible multiphase flow solver where phase tracking is handled with a discretely conservative volume of fluid method. This study presents statistics on velocity and volume fraction at different Reynolds and Weber numbers.

Evolved Gas Measurements Planned for the Lower Layers of the Gale Crater Mound with the Sample Analysis at Mars Instrument Suite

NASA Technical Reports Server (NTRS)

Mahaffy, Paul; Brunner, Anna; McAdam, Amy; Franz, Heather; Conrad, Pamela; Webster, Chris; Cabane, Michel

2009-01-01

The lower mound strata of Gale Crater provide a diverse set of chemical environments for exploration by the varied tools of the Curiosity Rover of the Mars Science Laboratory (MSL) Mission. Orbital imaging and spectroscopy clearly reveal distinct layers of hydrated minerals, sulfates, and clays with abundant evidence of a variety of fluvial processes. The three instruments of the MSL Sample Analysis at aMars (SAM) investigation, the Quadrupole Mass Spectrometer (QMS), the Tunable Laser Spectrometer (TLS), and the Gas Chromatograph (GC) are designed to analyze either atmospheric gases or volatiles thermally evolved or chemically extracted from powdered rock or soil. The presence or absence of organic compounds in these layers is of great interest since such an in situ search for this type of record has not been successfully implemented since the mid-60s Viking GCMS experiments. However, regardless of the outcome of the analysis for organics, the abundance and isotopic composition of thermally evolved inorganic compounds should also provide a rich data set to complement the mineralogical and elemental information provided by other MSL instruments. In addition, these evolved gas analysis (EGA) experiments will help test sedimentary models proposed by Malin and Edgett (2000) and then further developed by Milliken et al (2010) for Gale Crater. In the SAM EGA experiments the evolution temperatures of H2O, CO2, SO2, O2, or other simple compounds as the samples are heated in a helium stream to 1000 C provides information on mineral types and their associations. The isotopic composition of O, H, C, and S can be precisely determined in several evolved compounds and compared with the present day atmosphere. Such SAM results might be able to test mineralogical evidence of changing sedimentary and alteration processes over an extended period of time. For example, Bibring et al (2006) have suggested such a major shift from early nonacidic to later acidic alteration. We will illustrate through a variety of evolved gas experiments implemented under SAM-like gas flow and temperature ramp conditions on terrestrial analog minerals on high fidelity Sam breadboards the type of chemical information we expect SAM to provide.

Water resources and shale gas/oil production in the Appalachian Basin: critical issues and evolving developments

USGS Publications Warehouse

Kappel, William M.; Williams, John H.; Szabo, Zoltan

2013-01-01

Unconventional natural gas and oil resources in the United States are important components of a national energy program. While the Nation seeks greater energy independence and greener sources of energy, Federal agencies with environmental responsibilities, state and local regulators and water-resource agencies, and citizens throughout areas of unconventional shale gas development have concerns about the environmental effects of high volume hydraulic fracturing (HVHF), including those in the Appalachian Basin in the northeastern United States (fig. 1). Environmental concerns posing critical challenges include the availability and use of surface water and groundwater for hydraulic fracturing; the migration of stray gas and potential effects on overlying aquifers; the potential for flowback, formation fluids, and other wastes to contaminate surface water and groundwater; and the effects from drill pads, roads, and pipeline infrastructure on land disturbance in small watersheds and headwater streams (U.S. Government Printing Office, 2012). Federal, state, regional and local agencies, along with the gas industry, are striving to use the best science and technology to develop these unconventional resources in an environmentally safe manner. Some of these concerns were addressed in U.S. Geological Survey (USGS) Fact Sheet 2009–3032 (Soeder and Kappel, 2009) about potential critical effects on water resources associated with the development of gas extraction from the Marcellus Shale of the Hamilton Group (Ver Straeten and others, 1994). Since that time, (1) the extraction process has evolved, (2) environmental awareness related to high-volume hydraulic fracturing process has increased, (3) state regulations concerning gas well drilling have been modified, and (4) the practices used by industry to obtain, transport, recover, treat, recycle, and ultimately dispose of the spent fluids and solid waste materials have evolved. This report updates and expands on Fact Sheet 2009–3032 and presents new information regarding selected aspects of unconventional shale gas development in the Appalachian Basin (primarily Virginia, West Virginia, Maryland, Pennsylvania, Ohio, and New York). This document was prepared by the USGS, in cooperation with the U.S. Department of Energy, and reviews the evolving technical advances and scientific studies made in the Appalachian Basin between 2009 and the present (2013), addressing past and current issues for oil and gas development in the region.

Oil and gas impacts on transportation.

DOT National Transportation Integrated Search

2015-01-01

Colorados oil and gas industry is continually evolving, and there have been considerable changes in drilling techniques and geographic focus since the 2010 CDOT research study on Energy Development and the Transportation System. This research stud...

Sulphur-bearing Compounds Detected by MSL SAM Evolved Gas Analysis of Materials from Yellowknife Bay, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Franz, H. B.; Archer, P. D. Jr.; Sutter, B.; Eigenbrode, J. L.; Freissinet, C.; Atreya, S. K.; Bish, D. L.; Blake, D. F.; Brunner, A.;

Hot Gas in Merging Subgroups; Probing the Early Stages of Structure Formation

NASA Astrophysics Data System (ADS)

Machacek, Marie

2014-08-01

To fully understand the growth of large scale structure in hierarchical cosmological models, we must first understand how their building blocks, low mass galaxy subgroups, evolve through mergers. These galaxy subgroups are X-ray faint and difficult to observe at high redshift. The study of near-by subgroup mergers may be used as templates to gain insight into the dominant dynamical processes that are at work in the early universe. We use Chandra observations of edges, tails and wings in a sample of near-by galaxy groups ( Pavo, Telescopium, Pegasus, NGC7618/UGC12491 to measure the properties of the diffuse gas, merger velocities, shocks and non-hydrostatic gas 'sloshing', as their common ICM envelopes evolves.

Ionization in MHD-Gas interactions

NASA Astrophysics Data System (ADS)

Wilson, A.; Diver, D. A.

2013-09-01

The study of partially ionized plasmas is important in a number of astrophysical situations and is vital for the study of laboratory plasmas. The interactions between a neutral gas and a plasma define a hybrid medium that has aspects of each, but does not only sustain the pure modes of the individual species. Previously we have shown that momentum coupling between the gas and the magnetized plasma alters the behaviour of both; as an extension of that simulation, we present results for the extension to the coupling in which the relative motion between the species provides enough kinetic energy in the flow to allow a measure of species exchange Alfvén ionization (AI) (also known as critical velocity ionization), allowing the ionization fraction to evolve as the dynamics evolve.

Morphological change in machines accelerates the evolution of robust behavior

PubMed Central

Bongard, Josh

2011-01-01

Most animals exhibit significant neurological and morphological change throughout their lifetime. No robots to date, however, grow new morphological structure while behaving. This is due to technological limitations but also because it is unclear that morphological change provides a benefit to the acquisition of robust behavior in machines. Here I show that in evolving populations of simulated robots, if robots grow from anguilliform into legged robots during their lifetime in the early stages of evolution, and the anguilliform body plan is gradually lost during later stages of evolution, gaits are evolved for the final, legged form of the robot more rapidly—and the evolved gaits are more robust—compared to evolving populations of legged robots that do not transition through the anguilliform body plan. This suggests that morphological change, as well as the evolution of development, are two important processes that improve the automatic generation of robust behaviors for machines. It also provides an experimental platform for investigating the relationship between the evolution of development and robust behavior in biological organisms. PMID:21220304

Behavioral responses in structured populations pave the way to group optimality.

PubMed

Akçay, Erol; Van Cleve, Jeremy

2012-02-01

An unresolved controversy regarding social behaviors is exemplified when natural selection might lead to behaviors that maximize fitness at the social-group level but are costly at the individual level. Except for the special case of groups of clones, we do not have a general understanding of how and when group-optimal behaviors evolve, especially when the behaviors in question are flexible. To address this question, we develop a general model that integrates behavioral plasticity in social interactions with the action of natural selection in structured populations. We find that group-optimal behaviors can evolve, even without clonal groups, if individuals exhibit appropriate behavioral responses to each other's actions. The evolution of such behavioral responses, in turn, is predicated on the nature of the proximate behavioral mechanisms. We model a particular class of proximate mechanisms, prosocial preferences, and find that such preferences evolve to sustain maximum group benefit under certain levels of relatedness and certain ecological conditions. Thus, our model demonstrates the fundamental interplay between behavioral responses and relatedness in determining the course of social evolution. We also highlight the crucial role of proximate mechanisms such as prosocial preferences in the evolution of behavioral responses and in facilitating evolutionary transitions in individuality.

Searching for Reduced Carbon on the Surface of Mars: The SAM Combustion Experiment

NASA Technical Reports Server (NTRS)

Stern, J. C.; Malespin, C. A.; Mahaffy, P. R.; Webster, C. R.; Eigenbrode, J. L.; Archer, P. D., Jr.; Brunner, A. E.; Freissinet, C.; Franz, H. B.; Glavin, D. P.;

The Dynamics of Truncated Black Hole Accretion Disks. II. Magnetohydrodynamic Case

NASA Astrophysics Data System (ADS)

Hogg, J. Drew; Reynolds, Christopher S.

2018-02-01

We study a truncated accretion disk using a well-resolved, semi-global magnetohydrodynamic simulation that is evolved for many dynamical times (6096 inner disk orbits). The spectral properties of hard-state black hole binary systems and low-luminosity active galactic nuclei are regularly attributed to truncated accretion disks, but a detailed understanding of the flow dynamics is lacking. In these systems the truncation is expected to arise through thermal instability driven by sharp changes in the radiative efficiency. We emulate this behavior using a simple bistable cooling function with efficient and inefficient branches. The accretion flow takes on an arrangement where a “transition zone” exists in between hot gas in the innermost regions and a cold, Shakura & Sunyaev thin disk at larger radii. The thin disk is embedded in an atmosphere of hot gas that is fed by a gentle outflow originating from the transition zone. Despite the presence of hot gas in the inner disk, accretion is efficient. Our analysis focuses on the details of the angular momentum transport, energetics, and magnetic field properties. We find that the magnetic dynamo is suppressed in the hot, truncated inner region of the disk which lowers the effective α-parameter by 65%.

Global variation of the dust-to-gas ratio in evolving protoplanetary discs

NASA Astrophysics Data System (ADS)

Hughes, Anna L. H.; Armitage, Philip J.

2012-06-01

Recent theories suggest planetesimal formation via streaming and/or gravitational instabilities may be triggered by localized enhancements in the dust-to-gas ratio, and one hypothesis is that sufficient enhancements may be produced in the pile-up of small solid particles inspiralling under aerodynamic drag from the large mass reservoir in the outer disc. Studies of particle pile-up in static gas discs have provided partial support for this hypothesis. Here, we study the radial and temporal evolution of the dust-to-gas ratio in turbulent discs that evolve under the action of viscosity and photoevaporation. We find that particle pile-ups do not generically occur within evolving discs, particularly if the introduction of large grains is restricted to the inner, dense regions of a disc. Instead, radial drift results in depletion of solids from the outer disc, while the inner disc maintains a dust-to-gas ratio that is within a factor of ˜2 of the initial value. We attribute this result to the short time-scales for turbulent diffusion and radial advection (with the mean gas flow) in the inner disc. We show that the qualitative evolution of the dust-to-gas ratio depends only weakly upon the parameters of the disc model (the disc mass, size, viscosity and value of the Schmidt number), and discuss the implications for planetesimal formation via collective instabilities. Our results suggest that in discs where there is a significant level of midplane turbulence and accretion, planetesimal formation would need to be possible in the absence of large-scale enhancements. Instead, trapping and concentration of particles within local turbulent structures may be required as a first stage of planetesimal formation.

Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

NASA Astrophysics Data System (ADS)

Sutter, B.; McAdam, A. C.; Mahaffy, P. R.; Ming, D. W.; Edgett, K. S.; Rampe, E. B.; Eigenbrode, J. L.; Franz, H. B.; Freissinet, C.; Grotzinger, J. P.; Steele, A.; House, C. H.; Archer, P. D.; Malespin, C. A.; Navarro-González, R.; Stern, J. C.; Bell, J. F.; Calef, F. J.; Gellert, R.; Glavin, D. P.; Thompson, L. M.; Yen, A. S.

2017-12-01

The sample analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2, and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 ± 248-2373 ± 820 μgC(CO2)/g) and CO (11 ± 3-320 ± 130 μgC(CO)/g) suggest that organic C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32 ± 0.05-0.70 ± 0.1 wt % CO3). Evolved NO amounts to 0.002 ± 0.007-0.06 ± 0.03 wt % NO3. Evolution of O2 suggests that oxychlorine phases (chlorate/perchlorate) (0.05 ± 0.025-1.05 ± 0.44 wt % ClO4) are present, while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe and Mg sulfate and possibly sulfide. Evolved H2O (0.9 ± 0.3-2.5 ± 1.6 wt % H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest that reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, and carbonate). SAM results coupled with CheMin mineralogical and Alpha-Particle X-ray Spectrometer elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic C to support a small microbial population.

Sorption Modeling and Verification for Off-Gas Treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tavlarides, Lawrence; Yiacoumi, Sotira; Tsouris, Costas

2016-12-20

This project was successfully executed to provide valuable adsorption data and improve a comprehensive model developed in previous work by the authors. Data obtained were used in an integrated computer program to predict the behavior of adsorption columns. The model is supported by experimental data and has been shown to predict capture of off gas similar to that evolving during the reprocessing of nuclear waste. The computer program structure contains (a) equilibrium models of off-gases with the adsorbate; (b) mass-transfer models to describe off-gas mass transfer to a particle, diffusion through the pores of the particle, and adsorption on themore » active sites of the particle; and (c) incorporation of these models into fixed bed adsorption modeling, which includes advection through the bed. These models are being connected with the MOOSE (Multiphysics Object-Oriented Simulation Environment) software developed at the Idaho National Laboratory through DGOSPREY (Discontinuous Galerkin Off-gas SeParation and REcoverY) computer codes developed in this project. Experiments for iodine and water adsorption have been conducted on reduced silver mordenite (Ag0Z) for single layered particles. Adsorption apparatuses have been constructed to execute these experiments over a useful range of conditions for temperatures ranging from ambient to 250°C and water dew points ranging from -69 to 19°C. Experimental results were analyzed to determine mass transfer and diffusion of these gases into the particles and to determine which models best describe the single and binary component mass transfer and diffusion processes. The experimental results were also used to demonstrate the capabilities of the comprehensive models developed to predict single-particle adsorption and transients of the adsorption-desorption processes in fixed beds. Models for adsorption and mass transfer have been developed to mathematically describe adsorption kinetics and transport via diffusion and advection processes. These models were built on a numerical framework for solving conservation law problems in one-dimensional geometries such as spheres, cylinders, and lines. Coupled with the framework are specific models for adsorption in commercial adsorbents, such as zeolites and mordenites. Utilizing this modeling approach, the authors were able to accurately describe and predict adsorption kinetic data obtained from experiments at a variety of different temperatures and gas phase concentrations. A demonstration of how these models, and framework, can be used to simulate adsorption in fixed- bed columns is provided. The CO 2 absorption work involved modeling with supportive experimental information. A dynamic model was developed to simulate CO 2 absorption using high alkaline content water solutions. The model is based upon transient mass and energy balances for chemical species commonly present in CO 2 absorption. A computer code was developed to implement CO 2 absorption with a chemical reaction model. Experiments were conducted in a laboratory scale column to determine the model parameters. The influence of geometric parameters and operating variables on CO 2 absorption was studied over a wide range of conditions. Continuing work could employ the model to control column operation and predict the absorption behavior under various input conditions and other prescribed experimental perturbations. The value of the validated models and numerical frameworks developed in this project is that they can be used to predict the sorption behavior of off-gas evolved during the reprocessing of nuclear waste and thus reduce the cost of the experiments. They can also be used to design sorption processes based on concentration limits and flow-rates determined at the plant level.« less

Use of Computed X-ray Tomographic Data for Analyzing the Thermodynamics of a Dissociating Porous Sand/Hydrate Mixture

DOE R&D Accomplishments Database

Freifeld, Barry M.; Kneafsey, Timothy J.; Tomutsa, Liviu; Stern, Laura A.; Kirby, Stephen H.

2002-02-28

X-ray computed tomography (CT) is a method that has been used extensively in laboratory experiments for measuring rock properties and fluid transport behavior. More recently, CT scanning has been applied successfully to detect the presence and study the behavior of naturally occurring hydrates. In this study, we used a modified medical CT scanner to image and analyze the progression of a dissociation front in a synthetic methane hydrate/sand mixture. The sample was initially scanned under conditions at which the hydrate is stable (atmospheric pressure and liquid nitrogen temperature, 77 K). The end of the sample holder was then exposed to the ambient air, and the core was continuously scanned as dissociation occurred in response to the rising temperature. CT imaging captured the advancing dissociation front clearly and accurately. The evolved gas volume was monitored as a function of time. Measured by CT, the advancing hydrate dissociation front was modeled as a thermal conduction problem explicitly incorporating the enthalpy of dissociation, using the Stefan moving-boundary-value approach. The assumptions needed to perform the analysis consisted of temperatures at the model boundaries. The estimated value for thermal conductivity of 2.6 W/m K for the remaining water ice/sand mixture is higher than expected based on conduction alone; this high value may represent a lumped parameter that incorporates the processes of heat conduction, methane gas convection, and any kinetic effects that occur during dissociation. The technique presented here has broad implications for future laboratory and field testing that incorporates geophysical techniques to monitor gas hydrate dissociation.

Low-Resolution Vision-at the Hub of Eye Evolution.

PubMed

Nilsson, Dan-E; Bok, Michael J

2017-11-01

Simple roles for photoreception are likely to have preceded more demanding ones such as vision. The driving force behind this evolution is the improvement and elaboration of animal behaviors using photoreceptor input. Because the basic role for all senses aimed at the external world is to guide behavior, we argue here that understanding this "behavioral drive" is essential for unraveling the evolutionary past of the senses. Photoreception serves many different types of behavior, from simple shadow responses to visual communication. Based on minimum performance requirements for different types of tasks, photoreceptors have been argued to have evolved from non-directional receptors, via directional receptors, to low-resolution vision, and finally to high-resolution vision. Through this sequence, the performance requirements on the photoreceptors have gradually changed from broad to narrow angular sensitivity, from slow to fast response, and from low to high contrast sensitivity during the evolution from simple to more advanced and demanding behaviors. New behaviors would only evolve if their sensory performance requirements to some degree overlap with the requirements of already existing behaviors. This need for sensory "performance continuity" must have determined the order by which behaviors have evolved and thus been an important factor guiding animal evolution. Naturally, new behaviors are most likely to evolve from already existing behaviors with similar neural processing needs and similar motor responses, pointing to "neural continuity" as another guiding factor in sensory evolution. Here we use these principles to derive an evolutionary tree for behaviors driven by photoreceptor input. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Real-time visualization of soliton molecules with evolving behavior in an ultrafast fiber laser

NASA Astrophysics Data System (ADS)

Liu, Meng; Li, Heng; Luo, Ai-Ping; Cui, Hu; Xu, Wen-Cheng; Luo, Zhi-Chao

2018-03-01

Ultrafast fiber lasers have been demonstrated to be great platforms for the investigation of soliton dynamics. The soliton molecules, as one of the most fascinating nonlinear phenomena, have been a hot topic in the field of nonlinear optics in recent years. Herein, we experimentally observed the real-time evolving behavior of soliton molecule in an ultrafast fiber laser by using the dispersive Fourier transformation technology. Several types of evolving soliton molecules were obtained in our experiments, such as soliton molecules with monotonically or chaotically evolving phase, flipping and hopping phase. These results would be helpful to the communities interested in soliton nonlinear dynamics as well as ultrafast laser technologies.

Practical Problems in the Cement Industry Solved by Modern Research Techniques

ERIC Educational Resources Information Center

Daugherty, Kenneth E.; Robertson, Les D.

1972-01-01

Practical chemical problems in the cement industry are being solved by such techniques as infrared spectroscopy, gas chromatography-mass spectrometry, X-ray diffraction, atomic absorption and arc spectroscopy, thermally evolved gas analysis, Mossbauer spectroscopy, transmission and scanning electron microscopy. (CP)

Learning to Cooperate: The Evolution of Social Rewards in Repeated Interactions.

PubMed

Dridi, Slimane; Akçay, Erol

2018-01-01

Understanding the behavioral and psychological mechanisms underlying social behaviors is one of the major goals of social evolutionary theory. In particular, a persistent question about animal cooperation is to what extent it is supported by other-regarding preferences-the motivation to increase the welfare of others. In many situations, animals adjust their behaviors through learning by responding to the rewards they experience as a consequence of their actions. Therefore, we may ask whether learning in social situations can be driven by evolved other-regarding rewards. Here we develop a mathematical model in order to ask whether the mere act of cooperating with a social partner will evolve to be inherently rewarding. Individuals interact repeatedly in pairs and adjust their behaviors through reinforcement learning. We assume that individuals associate with each game outcome an internal reward value. These perceived rewards are genetically evolving traits. We find that conditionally cooperative rewards that value mutual cooperation positively but the sucker's outcome negatively tend to be evolutionarily stable. Purely other-regarding rewards can evolve only under special parameter combinations. On the other hand, selfish rewards that always lead to pure defection are also evolutionarily successful. These findings are consistent with empirical observations showing that humans tend to display conditionally cooperative behavior and also exhibit a diversity of preferences. Our model also demonstrates the need to further integrate multiple levels of biological causation of behavior.

Assessment of Prices of Natural Gas Futures Contracts As A Predictor of Realized Spot Prices, An

EIA Publications

2005-01-01

This article compares realized Henry Hub spot market prices for natural gas during the three most recent winters with futures prices as they evolve from April through the following February, when trading for the March contract ends.

Evolving Digital Ecological Networks

PubMed Central

Wagner, Aaron P.; Ofria, Charles

2013-01-01

“It is hard to realize that the living world as we know it is just one among many possibilities” [1]. Evolving digital ecological networks are webs of interacting, self-replicating, and evolving computer programs (i.e., digital organisms) that experience the same major ecological interactions as biological organisms (e.g., competition, predation, parasitism, and mutualism). Despite being computational, these programs evolve quickly in an open-ended way, and starting from only one or two ancestral organisms, the formation of ecological networks can be observed in real-time by tracking interactions between the constantly evolving organism phenotypes. These phenotypes may be defined by combinations of logical computations (hereafter tasks) that digital organisms perform and by expressed behaviors that have evolved. The types and outcomes of interactions between phenotypes are determined by task overlap for logic-defined phenotypes and by responses to encounters in the case of behavioral phenotypes. Biologists use these evolving networks to study active and fundamental topics within evolutionary ecology (e.g., the extent to which the architecture of multispecies networks shape coevolutionary outcomes, and the processes involved). PMID:23533370

Reduced and Oxidized Sulfur Compounds Detected by Evolved Gas Analyses of Materials from Yellowknife Bay, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Franz, H. B.; Archer, P. D., Jr.; Sutter, B.; Eigenbrode, J. L.; Freissinet, C.; Atreya, S. K.; Bish, D. L.; Blake, D. F.; Brunner, A.;

The evolution of courtship behaviors through the origination of a new gene in Drosophila

PubMed Central

Dai, Hongzheng; Chen, Ying; Chen, Sidi; Mao, Qiyan; Kennedy, David; Landback, Patrick; Eyre-Walker, Adam; Du, Wei; Long, Manyuan

2008-01-01

New genes can originate by the combination of sequences from unrelated genes or their duplicates to form a chimeric structure. These chimeric genes often evolve rapidly, suggesting that they undergo adaptive evolution and may therefore be involved in novel phenotypes. Their functions, however, are rarely known. Here, we describe the phenotypic effects of a chimeric gene, sphinx, that has recently evolved in Drosophila melanogaster. We show that a knockout of this gene leads to increased male–male courtship in D. melanogaster, although it leaves other aspects of mating behavior unchanged. Comparative studies of courtship behavior in other closely related Drosophila species suggest that this mutant phenotype of male–male courtship is the ancestral condition because these related species show much higher levels of male–male courtship than D. melanogaster. D. melanogaster therefore seems to have evolved in its courtship behaviors by the recruitment of a new chimeric gene. PMID:18508971

Representation in dynamical agents.

PubMed

Ward, Ronnie; Ward, Robert

2009-04-01

This paper extends experiments by Beer [Beer, R. D. (1996). Toward the evolution of dynamical neural networks for minimally cognitive behavior. In P. Maes, M. Mataric, J. Meyer, J. Pollack, & S. Wilson (Eds.), From animals to animats 4: Proceedings of the fourth international conference on simulation of adaptive behavior (pp. 421-429). MIT Press; Beer, R. D. (2003). The dynamics of active categorical perception in an evolved model agent (with commentary and response). Adaptive Behavior, 11 (4), 209-243] with an evolved, dynamical agent to further explore the question of representation in cognitive systems. Beer's environmentally-situated visual agent was controlled by a continuous-time recurrent neural network, and evolved to perform a categorical perception task, discriminating circles from diamonds. Despite the agent's high levels of discrimination performance, Beer found no evidence of internal representation in the best-evolved agent's nervous system. Here we examine the generality of this result. We evolved an agent for shape discrimination, and performed extensive behavioral analyses to test for representation. In this case we find that agents developed to discriminate equal-width shapes exhibit what Clark [Clark, A. (1997). The dynamical challenge. Cognitive Science, 21 (4), 461-481] calls "weak-substantive representation". The agent had internal configurations that (1) were understandably related to the object in the environment, and (2) were functionally used in a task relevant way when the target was not visible to the agent.

Differential Scanning Calorimetry and Evolved Gas Analysis of Hydromagnesite

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Golden, D. C.; Ming, Douglas W.; Boynton, W. V.

1999-01-01

Volatile-bearing minerals (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates and sulfates) may be important phases on the surface of Mars. In order to characterize these phases the Thermal and Evolved Gas Analyzer (TEGA) flying on the Mars'98 lander will perform analyses on surface samples from Mars. Hydromagnesite [Mg5(CO3)4(OH)2.4H2O] is considered a good standard mineral to examine as a Mars soil analog component because it evolves both H2O and CO2 at temperatures between 0 and 600 C. Our aim here is to interpret the DSC signature of hydromagnesite under ambient pressure and 20 sccm N2 flow in the range 25 to 600 C. The DSC curve for hydromagnesite under the above conditions consists of three endothermic peaks at temperatures 296, 426, and 548 and one sharp exotherm at 511 C. X-ray analysis of the sample at different stop temperatures suggested that the exotherm corresponded with the formation of crystalline magnesite. The first endotherm was due to dehydration of hydromagnesite, and then the second one was due to the decomposition of carbonate, immediately followed by the formation of magnesite (exotherm) and its decomposition to periclase (last endotherm). Evolution of water and CO2 were consistent with the observed enthalpy changes. A library of such DSC-evolved gas curves for putative Martian minerals are currently being acquired in order to facilitate the interpretation of results obtained by a robotic lander.

Numerical analysis of spin-orbit-coupled one-dimensional Fermi gas in a magnetic field

NASA Astrophysics Data System (ADS)

Chan, Y. H.

2015-06-01

Based on the density-matrix renormalization group and the infinite time-evolving block decimation methods we study the interacting spin-orbit-coupled 1D Fermi gas in a transverse magnetic field. We find that the system with an attractive interaction can have a polarized insulator phase, a superconducting (SC) phase, a Luther-Emery (LE) phase, and a band insulator phase as we vary the chemical potential and the strength of the magnetic field. Spin-orbit coupling (SOC) enhances the triplet pairing order at zero momentum in both the SC and the LE phase, which leads to an algebraically decaying correlation with the same exponent as that of the singlet pairing one. In contrast to the Fulde-Ferrell-Larkin-Ovchinnikov phase found in the spin imbalanced system without SOC, pairings at finite momentum in these two phases have larger exponents hence do not dictate the long-range behavior. We also test for the presence of Majorana fermions in this system. Unlike results from the mean-field study, we do not find positive evidence of Majorana fermions.

Effect of resistivity profile on current decay time of initial phase of current quench in neon-gas-puff inducing disruptions of JT-60U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawakami, S.; Ohno, N.; Shibata, Y.

2013-11-15

According to an early work [Y. Shibata et al., Nucl. Fusion 50, 025015 (2010)] on the behavior of the plasma current decay in the JT-60U disruptive discharges caused by the radiative collapse with a massive neon-gas-puff, the increase of the internal inductance mainly determined the current decay time of plasma current during the initial phase of current quench. To investigate what determines the increase of the internal inductance, we focus attention on the relationship between the electron temperature (or the resistivity) profile and the time evolution of the current density profile and carry out numerical calculations. As a result, wemore » find the reason of the increase of the internal inductance: The current density profile at the start of the current quench is broader than an expected current density profile in the steady state, which is determined by the temperature (or resistivity) profile. The current density profile evolves into peaked one and the internal inductance is increasing.« less

Euler-Lagrange Simulations of Shock Wave-Particle Cloud Interaction

NASA Astrophysics Data System (ADS)

Koneru, Rahul; Rollin, Bertrand; Ouellet, Frederick; Park, Chanyoung; Balachandar, S.

2017-11-01

Numerical experiments of shock interacting with an evolving and fixed cloud of particles are performed. In these simulations we use Eulerian-Lagrangian approach along with state-of-the-art point-particle force and heat transfer models. As validation, we use Sandia Multiphase Shock Tube experiments and particle-resolved simulations. The particle curtain upon interaction with the shock wave is expected to experience Kelvin-Helmholtz (KH) and Richtmyer-Meshkov (RM) instabilities. In the simulations evolving the particle cloud, the initial volume fraction profile matches with that of Sandia Multiphase Shock Tube experiments, and the shock Mach number is limited to M =1.66. Measurements of particle dispersion are made at different initial volume fractions. A detailed analysis of the influence of initial conditions on the evolution of the particle cloudis presented. The early time behavior of the models is studied in the fixed bed simulations at varying volume fractions and shock Mach numbers.The mean gas quantities are measured in the context of 1-way and 2-way coupled simulations. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

A platform for evolving intelligently interactive adversaries.

PubMed

Fogel, David B; Hays, Timothy J; Johnson, Douglas R

2006-07-01

Entertainment software developers face significant challenges in designing games with broad appeal. One of the challenges concerns creating nonplayer (computer-controlled) characters that can adapt their behavior in light of the current and prospective situation, possibly emulating human behaviors. This adaptation should be inherently novel, unrepeatable, yet within the bounds of realism. Evolutionary algorithms provide a suitable method for generating such behaviors. This paper provides background on the entertainment software industry, and details a prior and current effort to create a platform for evolving nonplayer characters with genetic and behavioral traits within a World War I combat flight simulator.

On sexual behavior and sex-role reversal.

PubMed

Schuiling, Gerard A

2005-09-01

Sex is not about reproduction; sex is about (re-)combination of DNA. Sex, not reproduction, always involves physical contact between two individuals; to achieve this, strategies of sexual behavior evolved. Sexual behavior, therefore, did not evolve as part of a reproductive strategy, but evolved to enable exchange of genetic material. In multicellular organisms the situation is more complicated than in unicellular organisms, as it is impossible for each cell within a multicellular body to have sex with another cell. Hence, evolution selected a system in which the possibility to have sex was limited to only one cell-line: the germ cells. As a result, sex adopted the character of fertilization, and sex and reproduction became inseparably linked. Still, in some species, including humans, sexual behavior still exhibits features of its evolutionary past: in humans (like in bonobo's) most sexual activity and many sexual behavioral patterns have nothing to do with reproduction (masturbation, homosexual behavior, for example); in humans, sexual behavior also became associated with other strategic objectives, such as intensifying the pair bond, expression of love or power. Different genders - male and female - evolved, and each gender evolved typical gender-related sexual and reproductive strategies as well. In most multicellular species, these strategies became inextricably mixed, and sexual behavior increasingly more - and in most species even exclusively - 'served' the interests of reproduction: sexual behavior became more or less synonymous with reproductive behavior. In most species, the 'mix' of sexual and reproductive strategies evolved into typical gender-related patterns of behavior, that is, in typical 'sex-roles'. Often, males are bigger and more 'beautiful' (= more intensely ornamented) than females; males compete with each other for access to females; males court females, while females choose males ('female choice'). However, ecological circumstances may cause a reversal of sex-roles, resulting in a situation in which females are bigger and more intensely ornamented than males, females compete for access to males, females court males and only males invest in care for the young, provided they are relatively certain of their paternity. Also, as in the case of the spotted hyena, females may be highly virilized and be socially dominant. This 'sex-role reversal' is seen, e.g., when males are relatively rare due to high predation pressure, or when the process of reproduction is very risky for the same reason: then it is 'better' that males, with their plenty of sperm, are wasted, than females with their few, precious eggs. It can be argued, with women being the fair sex, exhibiting competitive behavior and with an actively displaying courtship, and with men investing heavily in their offspring, meanwhile taking all (cultural) kinds of measures to guarantee their paternity, that humans, too, exhibit some degree of sex-role reversal.

Nonextensivity in a Dark Maximum Entropy Landscape

NASA Astrophysics Data System (ADS)

Leubner, M. P.

2011-03-01

Nonextensive statistics along with network science, an emerging branch of graph theory, are increasingly recognized as potential interdisciplinary frameworks whenever systems are subject to long-range interactions and memory. Such settings are characterized by non-local interactions evolving in a non-Euclidean fractal/multi-fractal space-time making their behavior nonextensive. After summarizing the theoretical foundations from first principles, along with a discussion of entropy bifurcation and duality in nonextensive systems, we focus on selected significant astrophysical consequences. Those include the gravitational equilibria of dark matter (DM) and hot gas in clustered structures, the dark energy(DE) negative pressure landscape governed by the highest degree of mutual correlations and the hierarchy of discrete cosmic structure scales, available upon extremizing the generalized nonextensive link entropy in a homogeneous growing network.

Miniature fuel cells relieve gas pressure in sealed batteries

NASA Technical Reports Server (NTRS)

Frank, H. A.

1971-01-01

Miniature fuel cells within sealed silver zinc batteries consume evolved hydrogen and oxygen rapidly, preventing pressure rupturing. They do not significantly increase battery weight and they operate in all battery life phases. Complete gas pressure control requires two fuel cells during all phases of operation of silver zinc batteries.

Chlorine Gas: An Evolving Hazardous Material Threat and Unconventional Weapon

PubMed Central

Jones, Robert; Wills, Brandon; Kang, Christopher

2010-01-01

Chlorine gas represents a hazardous material threat from industrial accidents and as a terrorist weapon. This review will summarize recent events involving chlorine disasters and its use by terrorists, discuss pre-hospital considerations and suggest strategies for the initial management for acute chlorine exposure events. PMID:20823965

Characterizing Environmental Transformation of Multi-walled Carbon Nanotubes and Carbon Nano-Fiber Composites using Thermal Analysis and Related Hyphenated Techniques

EPA Science Inventory

Thermogravimetric analysis (TGA) coupled with gas chromatography and mass spectroscopy (TGA/GCMS), for the evolved gas analysis, has given insight to the stability and kinetics of structural changes and determining adsorbed organics to nanomaterials and nanocomposites. TGA is als...

A 2D Micromodel Study of Fines Migration and Clogging Behavior in Porous Media: Implications of Fines on Methane Extraction from Hydrate-Bearing Sediments

NASA Astrophysics Data System (ADS)

Cao, S. C.; Jang, J.; Waite, W. F.; Jafari, M.; Jung, J.

2017-12-01

Fine-grained sediment, or "fines," exist nearly ubiquitously in natural sediment, even in the predominantly coarse-grained sediments that host gas hydrates. Fines within these sandy sediments can play a crucial role during gas hydrate production activities. During methane extraction, several processes can alter the mobility and clogging potential of fines: 1) fluid flow as the formation is depressurized to release methane from hydrate; 2) pore-fluid chemistry shifts as pore-fluid brine freshens due to pure water released from dissociating hydrate; 3) the presence of a moving gas/water interface as gas evolves from dissociating hydrate and moves through the reservoir toward the production well. To evaluate fines migration and clogging behavior changes resulting from methane gas production and pore-water freshening during hydrate dissociation, 2D micromodel experiments have been conducted on a selection of pure fines, pore-fluids, and micromodel pore-throat sizes. Additionally, tests have been run with and without an invading gas phase (CO2) to test the significance of a moving meniscus on fines mobility and clogging. The endmember fine particles chosen for this research include silica silt, mica, calcium carbonate, diatoms, kaolinite, illite, and bentonite (primarily made of montmorillonite). The pore fluids include deionized water, sodium chloride brine (2M concentration), and kerosene. The microfluidic pore models, used as porous media analogs, were fabricated with pore-throat widths of 40, 60, and 100 µm. Results from this research show that in addition to the expected dependence of clogging on the ratio of particle-to-pore-throat size, pore-fluid chemistry is also a significant factor because the interaction between a particular type of fine and pore fluid influences that fine's capacity to cluster, clump together and effectively increase its particle "size" relative to the pore-throat width. The presence of a moving gas/fluid meniscus increases the clogging potential regardless of fine type as the advancing meniscus tends to gather and concentrate the fines. Results show the need to identify both the type and concentration of fines prior to evaluating whether a system's clogging potential will increase or decrease as pore waters freshen during methane extraction from hydrate.

Evolved Gas Measurements Planned for the Lower Layers of the Gale Crater Mound with the Sample Analysis at Mars Instrument Suite

NASA Astrophysics Data System (ADS)

Mahaffy, P. R.; Franz, H.; McAdam, A.; Conrad, P. G.; Brunner, A.; Cabane, M.; Webster, C. R.

2011-12-01

The lower mound strata of Gale Crater provide a diverse set of chemical environments for exploration by the varied tools of the Curiosity Rover of the Mars Science Laboratory (MSL) Mission. Orbital imaging and spectroscopy clearly reveal distinct layers of hydrated minerals, sulfates, and clays with abundant evidence of a variety of fluvial processes. The three instruments of the MSL Sample Analysis at Mars (SAM) investigation, the Quadrupole Mass Spectrometer (QMS), the Tunable Laser Spectrometer (TLS), and the Gas Chromatograph (GC) are designed to analyze either atmospheric gases or volatiles thermally evolved or chemically extracted from powdered rock or soil. The presence or absence of organic compounds in these layers is of great interest since such an in situ search for this type of record has not been successfully implemented since the mid-70s Viking GCMS experiments. However, regardless of the outcome of the analysis for organics, the abundance and isotopic composition of thermally evolved inorganic compounds should also provide a rich data set to complement the mineralogical and elemental information provided by other MSL instruments. In addition, these evolved gas analysis (EGA) experiments will help test sedimentary models proposed by Malin and Edgett (2000) and then further developed by Milliken et al (2010) for Gale Crater. In the SAM EGA experiments the evolution temperatures of H2O, CO2, SO2, O2, or other simple compounds as the samples are heated in a helium stream to 1000C provides information on mineral types and their associations. The isotopic composition of O, H, C, and S can be precisely determined in several evolved compounds and compared with the present day atmosphere. Such SAM results might be able to test mineralogical evidence of changing sedimentary and alteration processes over an extended period of time. For example, Bibring et al (2006) have suggested such a major shift from early nonacidic to later acidic alteration. We will illustrate through a variety of evolved gas experiments implemented under SAM-like gas flow and temperature ramp conditions on terrestrial analog minerals on high fidelity SAM breadboards the type of chemical information we expect SAM to provide. Bibring, J.-P., et al. (2006), Global mineralogical and aqueous Mars history derived from OMEGA/Mars Express data, Science, 312, 400-404, doi:10.1126/science.1122659. Malin, M. C., and K. S. Edgett (2000), Sedimentary rocks of early Mars, Science, 290, 1927-1937, doi:10.1126/science.290.5498.1927. Milliken, R. E., J. P. Grotzinger, and B. J. Thomson (2010), Paleoclimate of Mars as captured by the strati- graphic record in Gale Crater, Geophys. Res. Lett., 37, L04201, doi:10.1029/2009GL041870.

Co-Evolution of Social Learning and Evolutionary Preparedness in Dangerous Environments

PubMed Central

Lindström, Björn; Selbing, Ida; Olsson, Andreas

2016-01-01

Danger is a fundamental aspect of the lives of most animals. Adaptive behavior therefore requires avoiding actions, objects, and environments associated with danger. Previous research has shown that humans and non-human animals can avoid such dangers through two types of behavioral adaptions, (i) genetic preparedness to avoid certain stimuli or actions, and (ii) social learning. These adaptive mechanisms reduce the fitness costs associated with danger but still allow flexible behavior. Despite the empirical prevalence and importance of both these mechanisms, it is unclear when they evolve and how they interact. We used evolutionary agent-based simulations, incorporating empirically based learning mechanisms, to clarify if preparedness and social learning typically both evolve in dangerous environments, and if these mechanisms generally interact synergistically or antagonistically. Our simulations showed that preparedness and social learning often co-evolve because they provide complimentary benefits: genetic preparedness reduced foraging efficiency, but resulted in a higher rate of survival in dangerous environments, while social learning generally came to dominate the population, especially when the environment was stochastic. However, even in this case, genetic preparedness reliably evolved. Broadly, our results indicate that the relationship between preparedness and social learning is important as it can result in trade-offs between behavioral flexibility and safety, which can lead to seemingly suboptimal behavior if the evolutionary environment of the organism is not taken into account. PMID:27487079

Co-Evolution of Social Learning and Evolutionary Preparedness in Dangerous Environments.

PubMed

Lindström, Björn; Selbing, Ida; Olsson, Andreas

2016-01-01

Danger is a fundamental aspect of the lives of most animals. Adaptive behavior therefore requires avoiding actions, objects, and environments associated with danger. Previous research has shown that humans and non-human animals can avoid such dangers through two types of behavioral adaptions, (i) genetic preparedness to avoid certain stimuli or actions, and (ii) social learning. These adaptive mechanisms reduce the fitness costs associated with danger but still allow flexible behavior. Despite the empirical prevalence and importance of both these mechanisms, it is unclear when they evolve and how they interact. We used evolutionary agent-based simulations, incorporating empirically based learning mechanisms, to clarify if preparedness and social learning typically both evolve in dangerous environments, and if these mechanisms generally interact synergistically or antagonistically. Our simulations showed that preparedness and social learning often co-evolve because they provide complimentary benefits: genetic preparedness reduced foraging efficiency, but resulted in a higher rate of survival in dangerous environments, while social learning generally came to dominate the population, especially when the environment was stochastic. However, even in this case, genetic preparedness reliably evolved. Broadly, our results indicate that the relationship between preparedness and social learning is important as it can result in trade-offs between behavioral flexibility and safety, which can lead to seemingly suboptimal behavior if the evolutionary environment of the organism is not taken into account.

Risks and risk governance in unconventional shale gas development.

PubMed

Small, Mitchell J; Stern, Paul C; Bomberg, Elizabeth; Christopherson, Susan M; Goldstein, Bernard D; Israel, Andrei L; Jackson, Robert B; Krupnick, Alan; Mauter, Meagan S; Nash, Jennifer; North, D Warner; Olmstead, Sheila M; Prakash, Aseem; Rabe, Barry; Richardson, Nathan; Tierney, Susan; Webler, Thomas; Wong-Parodi, Gabrielle; Zielinska, Barbara

2014-01-01

A broad assessment is provided of the current state of knowledge regarding the risks associated with shale gas development and their governance. For the principal domains of risk, we identify observed and potential hazards and promising mitigation options to address them, characterizing current knowledge and research needs. Important unresolved research questions are identified for each area of risk; however, certain domains exhibit especially acute deficits of knowledge and attention, including integrated studies of public health, ecosystems, air quality, socioeconomic impacts on communities, and climate change. For these, current research and analysis are insufficient to either confirm or preclude important impacts. The rapidly evolving landscape of shale gas governance in the U.S. is also assessed, noting challenges and opportunities associated with the current decentralized (state-focused) system of regulation. We briefly review emerging approaches to shale gas governance in other nations, and consider new governance initiatives and options in the U.S. involving voluntary industry certification, comprehensive development plans, financial instruments, and possible future federal roles. In order to encompass the multiple relevant disciplines, address the complexities of the evolving shale gas system and reduce the many key uncertainties needed for improved management, a coordinated multiagency federal research effort will need to be implemented.

Isotopic and Geochemical Investigation of Two Distinct Mars Analog Environments Using Evolved Gas Techniques in Svalbard, Norway

NASA Technical Reports Server (NTRS)

Stern, Jennifer Claire; Mcadam, Amy Catherine; Ten Kate, Inge L.; Bish, David L.; Blake, David F.; Morris, Richard V.; Bowden, Roxane; Fogel, Marilyn L.; Glamoclija, Mihaela; Mahaffy, Paul R.;

The Detection of Evolved Oxygen from the Rocknest Eolian Bedform Material by the Sample Analysis at Mars(SAM) instrument at the Mars Curiosity Landing Site

NASA Technical Reports Server (NTRS)

Sutter, B.; Archer, D.; Ming, D.; Eigenbrode, J. L.; Franz, H.; Glavin, D. P.; McAdam, A.; Mahaffy, P.; Stern, J.; Navarro-Gonzalex, R.;

The Mars Phoenix Thermal Evolved-Gas Analysis: The Role of an Organic Free Blank in the Search for Organics

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Ming, Douglas W.; Sutter, B.; Golden, D. C.; Morris, Richard V.; Boynton, W. V.

2008-01-01

The Thermal Evolved-Gas Analyzer (TEGA) instrument onboard the 2007 Phoenix Lander will perform differential scanning calorimetry (DSC) and evolved-gas analysis of soil samples collected from the surface. Data from the instrument will be compared with Mars analog mineral standards, collected under TEGA Mars-like conditions to identify the volatile-bearing mineral phases [1] (e.g., Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates) found in the Martian soil. Concurrently, the instrument will be looking for indications of organics that might also be present in the soil. Organic molecules are necessary building blocks for life, although their presence in the ice or soil does not indicate life itself. The spacecraft will certainly bring organic contaminants to Mars even though numerous steps were taken to minimize contamination during the spacecraft assembly and testing. It will be essential to distinguish possible Mars organics from terrestrial contamination when TEGA instrument begins analyzing icy soils. To address the above, an Organic Free Blank (OFB) was designed, built, tested, and mounted on the Phoenix spacecraft providing a baseline for distinguishing Mars organics from terrestrial organic contamination. Our objective in this report is to describe some of the considerations used in selecting the OFB material and then report on the processing and analysis of the final candidate material

Assessment of the Persistence of Vapour Evolved from Neat CH contamination on Prairie Terrain (Record of FPP-81-1)

DTIC Science & Technology

1983-01-01

infrared gas analyzer, equipped with a 20 m pathlenth gas cell , was used to obtain vapour concentration in real time. The sampling probe for the...lth’lt lrt’ nt1 ) sli tiongly absorbed by the vegetation. I-SIl KI(’TFl

Bubble Transport through Micropillar Arrays

NASA Astrophysics Data System (ADS)

Lee, Kenneth; Savas, Omer

2012-11-01

In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

Hydrodynamic characteristics of the two-phase flow field at gas-evolving electrodes: numerical and experimental studies

NASA Astrophysics Data System (ADS)

Liu, Cheng-Lin; Sun, Ze; Lu, Gui-Min; Yu, Jian-Guo

2018-05-01

Gas-evolving vertical electrode system is a typical electrochemical industrial reactor. Gas bubbles are released from the surfaces of the anode and affect the electrolyte flow pattern and even the cell performance. In the current work, the hydrodynamics induced by the air bubbles in a cold model was experimentally and numerically investigated. Particle image velocimetry and volumetric three-component velocimetry techniques were applied to experimentally visualize the hydrodynamics characteristics and flow fields in a two-dimensional (2D) plane and a three-dimensional (3D) space, respectively. Measurements were performed at different gas rates. Furthermore, the corresponding mathematical model was developed under identical conditions for the qualitative and quantitative analyses. The experimental measurements were compared with the numerical results based on the mathematical model. The study of the time-averaged flow field, three velocity components, instantaneous velocity and turbulent intensity indicate that the numerical model qualitatively reproduces liquid motion. The 3D model predictions capture the flow behaviour more accurately than the 2D model in this study.

Hydrodynamic characteristics of the two-phase flow field at gas-evolving electrodes: numerical and experimental studies.

PubMed

Liu, Cheng-Lin; Sun, Ze; Lu, Gui-Min; Yu, Jian-Guo

2018-05-01

Gas-evolving vertical electrode system is a typical electrochemical industrial reactor. Gas bubbles are released from the surfaces of the anode and affect the electrolyte flow pattern and even the cell performance. In the current work, the hydrodynamics induced by the air bubbles in a cold model was experimentally and numerically investigated. Particle image velocimetry and volumetric three-component velocimetry techniques were applied to experimentally visualize the hydrodynamics characteristics and flow fields in a two-dimensional (2D) plane and a three-dimensional (3D) space, respectively. Measurements were performed at different gas rates. Furthermore, the corresponding mathematical model was developed under identical conditions for the qualitative and quantitative analyses. The experimental measurements were compared with the numerical results based on the mathematical model. The study of the time-averaged flow field, three velocity components, instantaneous velocity and turbulent intensity indicate that the numerical model qualitatively reproduces liquid motion. The 3D model predictions capture the flow behaviour more accurately than the 2D model in this study.

Hydrodynamic characteristics of the two-phase flow field at gas-evolving electrodes: numerical and experimental studies

PubMed Central

Lu, Gui-Min; Yu, Jian-Guo

2018-01-01

Gas-evolving vertical electrode system is a typical electrochemical industrial reactor. Gas bubbles are released from the surfaces of the anode and affect the electrolyte flow pattern and even the cell performance. In the current work, the hydrodynamics induced by the air bubbles in a cold model was experimentally and numerically investigated. Particle image velocimetry and volumetric three-component velocimetry techniques were applied to experimentally visualize the hydrodynamics characteristics and flow fields in a two-dimensional (2D) plane and a three-dimensional (3D) space, respectively. Measurements were performed at different gas rates. Furthermore, the corresponding mathematical model was developed under identical conditions for the qualitative and quantitative analyses. The experimental measurements were compared with the numerical results based on the mathematical model. The study of the time-averaged flow field, three velocity components, instantaneous velocity and turbulent intensity indicate that the numerical model qualitatively reproduces liquid motion. The 3D model predictions capture the flow behaviour more accurately than the 2D model in this study. PMID:29892347

Is there any pristine gas in nearby starburst galaxies?

NASA Astrophysics Data System (ADS)

Lebouteiller, Vianney; Kunth, Daniel

2008-12-01

We derive the chemical composition of the neutral gas in the blue compact dwarf (BCD) Pox 36 observed with FUSE. Metals (N, O, Ar, and Fe) are underabundant as compared to the ionized gas associated with H ii regions by a factor ~7. The neutral gas, although it is not pristine, is thus probably less chemically evolved than the ionized gas. This could be due to different dispersal and mixing timescales. Results are compared to those of other BCDs observed with FUSE. The metallicity of the neutral gas in BCDs seems to reach a lower threshold of ~1/50 Z⊙ for extremely-metal poor galaxies.

Metal enrichment in the neutral gas of star-forming galaxies

NASA Astrophysics Data System (ADS)

Lebouteiller, V.; Kunth, D.; Désert, J.-M.; Thuan, T. X.

2009-05-01

We derive the chemical composition of the neutral gas in the blue compact dwarf (BCD) Pox 36 observed with FUSE. Metals (N, O, Ar, and Fe) are underabundant as compared to the ionized gas associated with H II regions by a factor ~7. The neutral gas, although it is not pristine, is thus probably less chemically evolved than the ionized gas. This could be due to different dispersal and mixing timescales. Results are compared to those of other BCDs observed with FUSE. The metallicity of the neutral gas in BCDs seems to reach a lower threshold of ~1/50Zsolar for extremely-metal poor galaxies.

Wild Origins: The Evolving Nature of Animal Behavior

NASA Astrophysics Data System (ADS)

Flores, Ifigenia

For billions of years, evolution has been the driving force behind the incredible range of biodiversity on our planet. Wild Origins is a concept plan for an exhibition at the National Zoo that uses case studies of animal behavior to explain the theory of evolution. Behaviors evolve, just as physical forms do. Understanding natural selection can help us interpret animal behavior and vice-versa. A living collection, digital media, interactives, fossils, and photographs will relay stories of social behavior, sex, navigation and migration, foraging, domestication, and relationships between different species. The informal learning opportunities visitors are offered at the zoo will create a connection with the exhibition's teaching points. Visitors will leave with an understanding and sense of wonder at the evolutionary view of life.

Evolving dynamics of trading behavior based on coordination game in complex networks

NASA Astrophysics Data System (ADS)

Bian, Yue-tang; Xu, Lu; Li, Jin-sheng

2016-05-01

This work concerns the modeling of evolvement of trading behavior in stock markets. Based on the assumption of the investors' limited rationality, the evolution mechanism of trading behavior is modeled according to the investment strategy of coordination game in network, that investors are prone to imitate their neighbors' activity through comprehensive analysis on the risk dominance degree of certain investment behavior, the network topology of their relationship and its heterogeneity. We investigate by mean-field analysis and extensive simulations the evolution of investors' trading behavior in various typical networks under different risk dominance degree of investment behavior. Our results indicate that the evolution of investors' behavior is affected by the network structure of stock market and the effect of risk dominance degree of investment behavior; the stability of equilibrium states of investors' behavior dynamics is directly related with the risk dominance degree of some behavior; connectivity and heterogeneity of the network plays an important role in the evolution of the investment behavior in stock market.

Thermal Decomposition Behavior of Hydroxytyrosol (HT) in Nitrogen Atmosphere Based on TG-FTIR Methods.

PubMed

Tu, Jun-Ling; Yuan, Jiao-Jiao

2018-02-13

The thermal decomposition behavior of olive hydroxytyrosol (HT) was first studied using thermogravimetry (TG). Cracked chemical bond and evolved gas analysis during the thermal decomposition process of HT were also investigated using thermogravimetry coupled with infrared spectroscopy (TG-FTIR). Thermogravimetry-Differential thermogravimetry (TG-DTG) curves revealed that the thermal decomposition of HT began at 262.8 °C and ended at 409.7 °C with a main mass loss. It was demonstrated that a high heating rate (over 20 K·min -1 ) restrained the thermal decomposition of HT, resulting in an obvious thermal hysteresis. Furthermore, a thermal decomposition kinetics investigation of HT indicated that the non-isothermal decomposition mechanism was one-dimensional diffusion (D1), integral form g ( x ) = x ², and differential form f ( x ) = 1/(2 x ). The four combined approaches were employed to calculate the activation energy ( E = 128.50 kJ·mol -1 ) and Arrhenius preexponential factor (ln A = 24.39 min -1 ). In addition, a tentative mechanism of HT thermal decomposition was further developed. The results provide a theoretical reference for the potential thermal stability of HT.

CONCEPTUAL MODEL FOR ORIGIN OF ABNORMALLY PRESSURED GAS ACCUMULATIONS IN LOW-PERMEABILITY RESERVOIRS.

USGS Publications Warehouse

Law, B.E.; Dickinson, W.W.

1985-01-01

The paper suggests that overpressured and underpressured gas accumulations of this type have a common origin. In basins containing overpressured gas accumulations, rates of thermogenic gas accumulation exceed gas loss, causing fluid (gas) pressure to rise above the regional hydrostatic pressure. Free water in the larger pores is forced out of the gas generation zone into overlying and updip, normally pressured, water-bearing rocks. While other diagenetic processes continue, a pore network with very low permeability develops. As a result, gas accumulates in these low-permeability reservoirs at rates higher than it is lost. In basins containing underpressured gas accumulations, rates of gas generation and accumulation are less than gas loss. The basin-center gas accumulation persists, but because of changes in the basin dynamics, the overpressured accumulation evolves into an underpressured system.

Cyclopentadiene evolution during pyrolysis-gas chromatography of PMR polyimides

NASA Technical Reports Server (NTRS)

Alston, William B.; Gluyas, Richard E.; Snyder, William J.

1992-01-01

The effect of formulated molecular weight (FMW), extent of cure, and cumulative aging on the amount of cyclopentadiene (CPD) evolved from Polymerization of Monomeric Reactants (PMR) polyimides were investigated by pyrolysis-gas chromotography (PY-GC). The PMR polyimides are additional crosslinked resins formed from an aromatic diamine, a diester of an aromatic tetracarboxylic acid and a monoester of 5-norbornene-2, 3-dicarboxylic acid. The PY-GC results were related to the degree of crosslinking and to the thermo-oxidative stability (weight loss) of PMR polyimides. Thus, PY-GC has shown to be a valid technique for the characterization of PMR polyimide resins and composites via correlation of the CPD evolved versus the thermal history of the PMR sample.

Robotic Arm Camera Image of the South Side of the Thermal and Evolved-Gas Analyzer (Door TA4

NASA Technical Reports Server (NTRS)

2008-01-01

The Thermal and Evolved-Gas Analyzer (TEGA) instrument aboard NASA's Phoenix Mars Lander is shown with one set of oven doors open and dirt from a sample delivery. After the 'seventh shake' of TEGA, a portion of the dirt sample entered the oven via a screen for analysis. This image was taken by the Robotic Arm Camera on Sol 18 (June 13, 2008), or 18th Martian day of the mission.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Surveying Professionals' Views of Positive Behavior Support and Behavior Analysis

ERIC Educational Resources Information Center

Filter, Kevin J.; Tincani, Matt; Fung, Daniel

2009-01-01

Positive behavior support (PBS) is an empirically driven approach to improve quality of life influenced by the science of behavior analysis. Recent discussions have evolved around PBS, behavior analysis, and their relationship within education and human services fields. To date, few data have been offered to guide behaviorally oriented…

Electrochemistry of single nanobubbles. Estimating the critical size of bubble-forming nuclei for gas-evolving electrode reactions.

PubMed

German, Sean R; Edwards, Martin A; Chen, Qianjin; Liu, Yuwen; Luo, Long; White, Henry S

2016-12-12

In this article, we address the fundamental question: "What is the critical size of a single cluster of gas molecules that grows and becomes a stable (or continuously growing) gas bubble during gas evolving reactions?" Electrochemical reactions that produce dissolved gas molecules are ubiquitous in electrochemical technologies, e.g., water electrolysis, photoelectrochemistry, chlorine production, corrosion, and often lead to the formation of gaseous bubbles. Herein, we demonstrate that electrochemical measurements of the dissolved gas concentration, at the instant prior to nucleation of an individual nanobubble of H 2 , N 2 , or O 2 at a Pt nanodisk electrode, can be analyzed using classical thermodynamic relationships (Henry's law and the Young-Laplace equation - including non-ideal corrections) to provide an estimate of the size of the gas bubble nucleus that grows into a stable bubble. We further demonstrate that this critical nucleus size is independent of the radius of the Pt nanodisk employed (<100 nm radius), and weakly dependent on the nature of the gas. For example, the measured critical surface concentration of H 2 of ∼0.23 M at the instant of bubble formation corresponds to a critical H 2 nucleus that has a radius of ∼3.6 nm, an internal pressure of ∼350 atm, and contains ∼1700 H 2 molecules. The data are consistent with stochastic fluctuations in the density of dissolved gas, at or near the Pt/solution interface, controlling the rate of bubble nucleation. We discuss the growth of the nucleus as a diffusion-limited process and how that process is affected by proximity to an electrode producing ∼10 11 gas molecules per second. Our study demonstrates the advantages of studying a single-entity, i.e., an individual nanobubble, in understanding and quantifying complex physicochemical phenomena.

Balance of oxygen throughout the conversion of a high-level waste melter feed to glass

DOE PAGES

Lee, SeungMin; Hrma, Pavel; Kloužek, Jaroslav; ...

2017-07-03

Gases evolve from nuclear waste melter feed during conversion to glass in response to heating. This article is focused on oxygen mass balance based on the stoichiometry of feed melting reactions and evolved-gas analysis data. Whereas O 2-producing and -consuming batch-melting reactions are complete in the reacting and primary-foam layers of the cold cap, O 2 from redox reactions continues to evolve as long as melt temperature increases, and thus generates secondary foam. Also, we discuss the relationship between the oxygen mass balance and the temperature-dependent iron redox ratio and the O 2 partial pressure, as they evolve during themore » feed-to-glass conversion.« less

Balance of oxygen throughout the conversion of a high-level waste melter feed to glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, SeungMin; Hrma, Pavel; Kloužek, Jaroslav

Gases evolve from nuclear waste melter feed during conversion to glass in response to heating. This article is focused on oxygen mass balance based on the stoichiometry of feed melting reactions and evolved-gas analysis data. Whereas O 2-producing and -consuming batch-melting reactions are complete in the reacting and primary-foam layers of the cold cap, O 2 from redox reactions continues to evolve as long as melt temperature increases, and thus generates secondary foam. Also, we discuss the relationship between the oxygen mass balance and the temperature-dependent iron redox ratio and the O 2 partial pressure, as they evolve during themore » feed-to-glass conversion.« less

Adaptive Evolution under Extreme Genetic Drift in Oxidatively Stressed Caenorhabditis elegans

PubMed Central

Christy, Stephen F; Wernick, Riana I; Lue, Michael J; Velasco, Griselda; Howe, Dana K; Denver, Dee R

2017-01-01

Abstract A mutation-accumulation (MA) experiment with Caenorhabditis elegans nematodes was conducted in which replicate, independently evolving lines were initiated from a low-fitness mitochondrial electron transport chain mutant, gas-1. The original intent of the study was to assess the effect of electron transport chain dysfunction involving elevated reactive oxygen species production on patterns of spontaneous germline mutation. In contrast to results of standard MA experiments, gas-1 MA lines evolved slightly higher mean fitness alongside reduced among-line genetic variance compared with their ancestor. Likewise, the gas-1 MA lines experienced partial recovery to wildtype reactive oxygen species levels. Whole-genome sequencing and analysis revealed that the molecular spectrum but not the overall rate of nuclear DNA mutation differed from wildtype patterns. Further analysis revealed an enrichment of mutations in loci that occur in a gas-1-centric region of the C. elegans interactome, and could be classified into a small number of functional-genomic categories. Characterization of a backcrossed four-mutation set isolated from one gas-1 MA line revealed this combination to be beneficial on both gas-1 mutant and wildtype genetic backgrounds. Our combined results suggest that selection favoring beneficial mutations can be powerful even under unfavorable population genetic conditions, and agree with fitness landscape theory predicting an inverse relationship between population fitness and the likelihood of adaptation. PMID:29069345

The highly ionized, high-velocity gas in NGC 6231

NASA Astrophysics Data System (ADS)

Massa, Derck

2017-02-01

It is well known that clusters of massive stars are influenced by the presence of strong winds, that they are sources of diffuse X-rays from shocked gas, and that this gas can be vented into the surrounding region or the halo through the champagne effect. However, the details of how these different environments interact and evolve are far from complete. This paper attributes the broad C IVλλ1500 absorption features (extending to -1900 km s-1) that are seen in the spectra of main sequence B stars in NGC 6231 to gas in the cluster environment and not the B stars themselves. It is shown that the presence of a WC star, WR 79, in the cluster makes this gas detectable because its wind enriches the cluster gas with carbon. Given the available data, it is not clear whether the absorbing gas is simply the far wind of WR 79 or a collective cluster wind enriched by carbon from the wind of WR 79. If it is simply due to the wind, then this wind must flow, unimpeded for more than 2 pc, suggesting that the inner region of the cluster is nearly devoid of obstructing material. If it is actually a collective wind from the cluster, then we could be witnessing an important stage of galactic feedback. In either case, the observations provide a unique and significant piece to the puzzle of how massive, open clusters evolve.

THE EVOLUTION OF CIRCUMPLANETARY DISKS AROUND PLANETS IN WIDE ORBITS: IMPLICATIONS FOR FORMATION THEORY, OBSERVATIONS, AND MOON SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shabram, Megan; Boley, Aaron C.

2013-04-10

Using radiation hydrodynamics simulations, we explore the evolution of circumplanetary disks around wide-orbit proto-gas giants. At large distances from the star ({approx}100 AU), gravitational instability followed by disk fragmentation can form low-mass substellar companions (massive gas giants and/or brown dwarfs) that are likely to host large disks. We examine the initial evolution of these subdisks and their role in regulating the growth of their substellar companions, as well as explore consequences of their interactions with circumstellar material. We find that subdisks that form in the context of GIs evolve quickly from a very massive state. Long-term accretion rates from themore » subdisk onto the proto-gas giant reach {approx}0.3 Jupiter masses kyr{sup -1}. We also find consistency with previous simulations, demonstrating that subdisks are truncated at {approx}1/3 of the companion's Hill radius and are thick, with (h/r) of {approx}> 0.2. The thickness of subdisks draws to question the use of thin-disk approximations for understanding the behavior of subdisks, and the morphology of subdisks has implications for the formation and extent of satellite systems. These subdisks create heating events in otherwise cold regions of the circumstellar disk and serve as planet formation beacons that can be detected by instruments such as ALMA.« less

Fundamental Physics

NASA Image and Video Library

2003-01-22

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Major Volatiles from MSL SAM Evolved Gas Analyses: Yellowknife Bay Through Lower Mount Sharp

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Archer, P. D., Jr.; Sutter, B.; Franz, H. B.; Eigenbrode, J. L.; Ming, D. W.; Morris, R. V.; Niles, P. B.; Stern, J. C.; Freissinet, C.;

U.S. Natural Gas Markets: Mid-Term Prospects for Natural Gas Supply

EIA Publications

2001-01-01

This service report describes the recent behavior of natural gas markets with respect to natural gas prices, their potential future behavior, the potential future supply contribution of liquefied natural gas and increased access to federally restricted resources, and the need for improved natural gas data.

REM Sleep Behavior Disorder: Updated Review of the Core Features, the RBD-Neurodegenerative Disease Association, Evolving Concepts, Controversies, and Future Directions

PubMed Central

Boeve, Bradley F.

2010-01-01

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia manifested by vivid, often frightening dreams associated with simple or complex motor behavior during REM sleep. Patients appear to “act out their dreams,” in which the exhibited behaviors mirror the content of the dreams, and the dream content often involves a chasing or attacking theme. The polysomnographic features of RBD include increased electromyographic tone +/- dream enactment behavior during REM sleep. Management with counseling and pharmacologic measures is usually straight-forward and effective. In this review, the terminology, clinical and polysomnographic features, demographic and epidemiologic features, diagnostic criteria, differential diagnosis, and management strategies are discussed. Recent data on the suspected pathophysiologic mechanisms of RBD are also reviewed. The literature and our institutional experience on RBD are next discussed, with an emphasis on the RBD-neurodegenerative disease association and particularly the RBD-synucleinopathy association. Several issues relating to evolving concepts, controversies, and future directions are then reviewed, with an emphasis on idiopathic RBD representing an early feature of a neurodegenerative disease and particularly an evolving synucleinopathy. Planning for future therapies that impact patients with idiopathic RBD is reviewed in detail. PMID:20146689

shock driven instability of a multi-phase particle-gas system

NASA Astrophysics Data System (ADS)

McFarland, Jacob; Black, Wolfgang; Dahal, Jeevan; Morgan, Brandon

2015-11-01

A computational study of a shock driven instability of a multiphse particle-gas system is presented. This instability can evolve in a similar fashion to the Richtmyer-Meshkov (RM) instability, but has addition parameters to be considered. Particle relaxation times, and density differences of the gas and particle-gas system can be adjusted to produce results which are different from the classical RM instability. We will show simulation results from the Ares code, developed at Lawrence Livermore National Laboratory, which uses a particle-in-cell approach to study the effects of the particle-gas system parameters. Mixing parameters will be presented to highlight the suppression of circulation and gas mixing by the particle phase.

Aging in freely evolving granular gas with impact velocity dependent coefficient of restitution

NASA Astrophysics Data System (ADS)

Kumari, Shikha; Ahmad, Syed Rashid

2018-05-01

The evolution of granular system is governed by the concept of coefficient of restitution that gives a relationship between normal component of relative velocities before and after collision. Most of the studies consider a simplified collision model where particles interact through coefficient of restitution which is a constant while in reality, the coefficient of restitution must be a variable that depends on the impact velocity of colliding particles. In this work, we have considered the aging in the velocity autocorrelation function, A(τw, τ) for a granular gas of realistic particles interacting through coefficient of restitution that is depending on impact velocity. Molecular dynamics simulation is used to study granular gas that is evolving freely in absence of any external force. From the simulation results, we observe that A(τw, τ) depends explicitly on waiting time τw and collision time τ. Initially, the function decays exponentially but as the waiting time increases the decay of function becomes slow due to correlations that emerge in velocity field.

What Are Punishment and Reputation for?

PubMed Central

Krasnow, Max M.; Cosmides, Leda; Pedersen, Eric J.; Tooby, John

2012-01-01

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven’t punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld–its circuit logic–support the hypothesis that it is generated by psychological mechanisms that evolved to benefit the punisher, by allowing him to bargain for better treatment. PMID:23049833

What are punishment and reputation for?

PubMed

Krasnow, Max M; Cosmides, Leda; Pedersen, Eric J; Tooby, John

2012-01-01

Why did punishment and the use of reputation evolve in humans? According to one family of theories, they evolved to support the maintenance of cooperative group norms; according to another, they evolved to enhance personal gains from cooperation. Current behavioral data are consistent with both hypotheses (and both selection pressures could have shaped human cooperative psychology). However, these hypotheses lead to sharply divergent behavioral predictions in circumstances that have not yet been tested. Here we report results testing these rival predictions. In every test where social exchange theory and group norm maintenance theory made different predictions, subject behavior violated the predictions of group norm maintenance theory and matched those of social exchange theory. Subjects do not direct punishment toward those with reputations for norm violation per se; instead, they use reputation self-beneficially, as a cue to lower the risk that they personally will experience losses from defection. More tellingly, subjects direct their cooperative efforts preferentially towards defectors they have punished and away from those they haven't punished; they avoid expending punitive effort on reforming defectors who only pose a risk to others. These results are not consistent with the hypothesis that the psychology of punishment evolved to uphold group norms. The circumstances in which punishment is deployed and withheld-its circuit logic-support the hypothesis that it is generated by psychological mechanisms that evolved to benefit the punisher, by allowing him to bargain for better treatment.

A Change Impact Analysis to Characterize Evolving Program Behaviors

NASA Technical Reports Server (NTRS)

Rungta, Neha Shyam; Person, Suzette; Branchaud, Joshua

2012-01-01

Change impact analysis techniques estimate the potential effects of changes made to software. Directed Incremental Symbolic Execution (DiSE) is an intraprocedural technique for characterizing the impact of software changes on program behaviors. DiSE first estimates the impact of the changes on the source code using program slicing techniques, and then uses the impact sets to guide symbolic execution to generate path conditions that characterize impacted program behaviors. DiSE, however, cannot reason about the flow of impact between methods and will fail to generate path conditions for certain impacted program behaviors. In this work, we present iDiSE, an extension to DiSE that performs an interprocedural analysis. iDiSE combines static and dynamic calling context information to efficiently generate impacted program behaviors across calling contexts. Information about impacted program behaviors is useful for testing, verification, and debugging of evolving programs. We present a case-study of our implementation of the iDiSE algorithm to demonstrate its efficiency at computing impacted program behaviors. Traditional notions of coverage are insufficient for characterizing the testing efforts used to validate evolving program behaviors because they do not take into account the impact of changes to the code. In this work we present novel definitions of impacted coverage metrics that are useful for evaluating the testing effort required to test evolving programs. We then describe how the notions of impacted coverage can be used to configure techniques such as DiSE and iDiSE in order to support regression testing related tasks. We also discuss how DiSE and iDiSE can be configured for debugging finding the root cause of errors introduced by changes made to the code. In our empirical evaluation we demonstrate that the configurations of DiSE and iDiSE can be used to support various software maintenance tasks

Atmospheric Pressure Effects on Cryogenic Storage Tank Boil-Off

NASA Technical Reports Server (NTRS)

Sass, J. P.; Frontier, C. R.

2007-01-01

The Cryogenics Test Laboratory (CTL) at the Kennedy Space Center (KSC) routinely utilizes cryostat test hardware to evaluate comparative and absolute thermal conductivities of a wide array of insulation systems. The test method is based on measurement of the flow rate of gas evolved due to evaporative boil-off of a cryogenic liquid. The gas flow rate typically stabilizes after a period of a couple of hours to a couple of days, depending upon the test setup. The stable flow rate value is then used to calculate the thermal conductivity for the insulation system being tested. The latest set of identical cryostats, 1,000-L spherical tanks, exhibited different behavior. On a macro level, the flow rate did stabilize after a couple of days; however the stable flow rate was oscillatory with peak to peak amplitude of up to 25 percent of the nominal value. The period of the oscillation was consistently 12 hours. The source of the oscillation has been traced to variations in atmospheric pressure due to atmospheric tides similar to oceanic tides. This paper will present analysis of this phenomenon, including a calculation that explains why other cryostats are not affected by it.

MODELING FLOWS AROUND MERGING BLACK HOLE BINARIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Meter, James R.; Centrella, Joan; Baker, John G.

2010-03-10

Coalescing massive black hole binaries are produced by the mergers of galaxies. The final stages of the black hole coalescence produce strong gravitational radiation that can be detected by the space-borne Laser Interferometer Space Antenna. In cases where the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We have taken a step toward solving this problem by mapping the flow ofmore » pressureless matter in the dynamic, three-dimensional general relativistic spacetime around the merging black holes. We find qualitative differences in collision and outflow speeds, including a signature of the merger when the net angular momentum of the matter is low, between the results from single and binary black holes, and between nonrotating and rotating holes in binaries. If future magnetohydrodynamic results confirm these differences, it may allow assessment of the properties of the binaries as well as yielding an identifiable electromagnetic counterpart to the attendant gravitational wave signal.« less

Exotic superfluidity and pairing phenomena in atomic Fermi gases in mixed dimensions.

PubMed

Zhang, Leifeng; Che, Yanming; Wang, Jibiao; Chen, Qijin

2017-10-11

Atomic Fermi gases have been an ideal platform for simulating conventional and engineering exotic physical systems owing to their multiple tunable control parameters. Here we investigate the effects of mixed dimensionality on the superfluid and pairing phenomena of a two-component ultracold atomic Fermi gas with a short-range pairing interaction, while one component is confined on a one-dimensional (1D) optical lattice whereas the other is in a homogeneous 3D continuum. We study the phase diagram and the pseudogap phenomena throughout the entire BCS-BEC crossover, using a pairing fluctuation theory. We find that the effective dimensionality of the non-interacting lattice component can evolve from quasi-3D to quasi-1D, leading to strong Fermi surface mismatch. Upon pairing, the system becomes effectively quasi-two dimensional in the BEC regime. The behavior of T c bears similarity to that of a regular 3D population imbalanced Fermi gas, but with a more drastic departure from the regular 3D balanced case, featuring both intermediate temperature superfluidity and possible pair density wave ground state. Unlike a simple 1D optical lattice case, T c in the mixed dimensions has a constant BEC asymptote.

Evolution of synchronization and desynchronization in digital organisms.

PubMed

Knoester, David B; McKinley, Philip K

2011-01-01

We present a study in the evolution of temporal behavior, specifically synchronization and desynchronization, through digital evolution and group selection. In digital evolution, a population of self-replicating computer programs exists in a user-defined computational environment and is subject to instruction-level mutations and natural selection. Group selection links the survival of the individual to the survival of its group, thus encouraging cooperation. Previous approaches to engineering synchronization and desynchronization algorithms have taken inspiration from nature: In the well-known firefly model, the only form of communication between agents is in the form of flash messages among neighbors. Here we demonstrate that populations of digital organisms, provided with a similar mechanism and minimal information about their environment, are capable of evolving algorithms for synchronization and desynchronization, and that the evolved behaviors are robust to message loss. We further describe how the evolved behavior for synchronization mimics that of the well-known Ermentrout model for firefly synchronization in biology. In addition to discovering self-organizing behaviors for distributed computing systems, this result indicates that digital evolution may be used to further our understanding of synchronization in biology.

Bar formation as driver of gas inflows in isolated disc galaxies

NASA Astrophysics Data System (ADS)

Fanali, R.; Dotti, M.; Fiacconi, D.; Haardt, F.

2015-12-01

Stellar bars are a common feature in massive disc galaxies. On a theoretical ground, the response of gas to a bar is generally thought to cause nuclear starbursts and, possibly, AGN activity once the perturbed gas reaches the central supermassive black hole. By means of high-resolution numerical simulations, we detail the purely dynamical effects that a forming bar exerts on the gas of an isolated disc galaxy. The galaxy is initially unstable to the formation of non-axisymmetric structures, and within ˜1 Gyr it develops spiral arms that eventually evolve into a central stellar bar on kpc scale. A first major episode of gas inflow occurs during the formation of the spiral arms while at later times, when the stellar bar is establishing, a low-density region is carved between the bar corotational and inner Lindblad resonance radii. The development of such `dead zone' inhibits further massive gas inflows. Indeed, the gas inflow reaches its maximum during the relatively fast bar-formation phase and not, as often assumed, when the bar is fully formed. We conclude that the low efficiency of long-lived, evolved bars in driving gas towards galactic nuclei is the reason why observational studies have failed to establish an indisputable link between bars and AGNs. On the other hand, the high efficiency in driving strong gas inflows of the intrinsically transient process of bar formation suggests that the importance of bars as drivers of AGN activity in disc galaxies has been overlooked so far. We finally prove that our conclusions are robust against different numerical implementations of the hydrodynamics routinely used in galaxy evolution studies.

Global Evolution of Solid Matter in Turbulent Protoplanetry Disks. Part 1; Aerodynamics of Solid Particles

NASA Technical Reports Server (NTRS)

Stepinski, T. F.; Valageas, P.

1996-01-01

The problem of planetary system formation and its subsequent character can only be addressed by studying the global evolution of solid material entrained in gaseous protoplanetary disks. We start to investigate this problem by considering the space-time development of aerodynamic forces that cause solid particles to decouple from the gas. The aim of this work is to demonstrate that only the smallest particles are attached to the gas, or that the radial distribution of the solid matter has no momentary relation to the radial distribution of the gas. We present the illustrative example wherein a gaseous disk of 0.245 solar mass and angular momentum of 5.6 x 10(exp 52) g/sq cm/s is allowed to evolve due to turbulent viscosity characterized by either alpha = 10(exp -2) or alpha = 10(exp -3). The motion of solid particles suspended in a viscously evolving gaseous disk is calculated numerically for particles of different sizes. In addition we calculate the global evolution of single-sized, noncoagulating particles. We find that particles smaller than 0.1 cm move with the gas; larger particles have significant radial velocities relative to the gas. Particles larger than 0.1 cm but smaller than 10(exp 3) cm have inward radial velocities much larger than the gas, whereas particles larger than 10(exp 4) cm have inward velocities much smaller than the gas. A significant difference in the form of the radial distribution of solids and the gas develops with time. It is the radial distribution of solids, rather than the gas, that determines the character of an emerging planetary system.

Evolving the future: Toward a science of intentional change

PubMed Central

Wilson, David Sloan; Hayes, Steven C.; Biglan, Anthony; Embry, Dennis D.

2015-01-01

Humans possess great capacity for behavioral and cultural change, but our ability to manage change is still limited. This article has two major objectives: first, to sketch a basic science of intentional change centered on evolution; second, to provide examples of intentional behavioral and cultural change from the applied behavioral sciences, which are largely unknown to the basic sciences community. All species have evolved mechanisms of phenotypic plasticity that enable them to respond adaptively to their environments. Some mechanisms of phenotypic plasticity count as evolutionary processes in their own right. The human capacity for symbolic thought provides an inheritance system having the same kind of combinatorial diversity as does genetic recombination and antibody formation. Taking these propositions seriously allows an integration of major traditions within the basic behavioral sciences, such as behaviorism, social constructivism, social psychology, cognitive psychology, and evolutionary psychology, which are often isolated and even conceptualized as opposed to one another. The applied behavioral sciences include well-validated examples of successfully managing behavioral and cultural change at scales ranging from individuals to small groups to large populations. However, these examples are largely unknown beyond their disciplinary boundaries, for lack of a unifying theoretical framework. Viewed from an evolutionary perspective, they are examples of managing evolved mechanisms of phenotypic plasticity, including open-ended processes of variation and selection. Once the many branches of the basic and applied behavioral sciences become conceptually unified, we are closer to a science of intentional change than one might think. PMID:24826907

Membrane water deaerator investigation. [fluid filter breadboard model

NASA Technical Reports Server (NTRS)

Elam, J.; Ruder, J.; Strumpf, H.

1974-01-01

The purpose of the membrane water deaerator program was to develop data on a breadboard hollow fiber membrane unit that removes both dissolved and evolved gas from a water transfer system in order to: (1) assure a hard fill of the EVLSS expendable water tank; (2) prevent flow blockage by gas bubbles in circulating systems; and (3) prevent pump cavitation.

Carbon Isotopic Composition of CO2, Evolved During Perchlorate-Induced Reactions in Mars Analog Materials: Interpreting SAM/MSL Rocknest Data

NASA Technical Reports Server (NTRS)

Stern, J. C.; McAdam, A. C.; Archer, P. D., Jr.; Bower, H.; Buch, A.; Eigenbrode, J.; Freissinet, C.; Franz, H. B.; Glavin, D.; Jones, J. H.;

A Possible Organic Contribution to the Low Temperature CO2 Release Seen in Mars Phoenix Thermal and Evolved Gas Analyzer Data

NASA Technical Reports Server (NTRS)

Archer, P. D. Jr.; Lauer, H. V., Jr.; Sutter, B.; Ming, D. W.; Niles, P. B.; Boynton, W. V.

2012-01-01

Two of the most important discoveries of the Phoenix Mars Lander were the discovery of approx.0.6% perchlorate [1] and 3-5% carbonate [2] in the soils at the landing site in the martian northern plains. The Thermal and Evolved Gas Analyzer (TEGA) instrument was one of the tools that made this discovery. After soil samples were delivered to TEGA and transferred into small ovens, the samples could be heated up to approx.1000 C and the gases that evolved during heating were monitored by a mass spectrometer. A CO2 signal was detected at high temperature (approx.750 C) that has been attributed to calcium carbonate decomposition. In addition to this CO2 release, a lower temperature signal was seen. This lower temperature CO2 release was postulated to be one of three things: 1) desorption of CO2, 2) decomposition of a different carbonate mineral, or 3) CO2 released due to organic combustion. Cannon et al. [3] present another novel hypothesis involving the interaction of decomposition products of a perchlorate salt and calcium carbonate.

Thermally evolved gas analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru: Implications for the Phoenix mission

NASA Astrophysics Data System (ADS)

Valdivia-Silva, Julio E.; Navarro-González, Rafael; McKay, Christopher

2009-07-01

TEGA, one of several instruments on board of the Phoenix Lander, performed differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high temperature furnace and a mass spectrometer (MS) that was used to analyze samples delivered to the instrument via a robotic arm. The samples were heated at a programmed ramp rate up to 1000 °C. The power required for heating can be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process can be analyzed with the evolved gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolyzer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the evolved gas properties of six types of hyperarid soils from the Pampas de La Joya in southern Peru (a possible analog to Mars), to which we have added with microorganisms ( Salmonella typhimurium, Micrococcus luteus, and Candida albicans) in order to investigate the effect of the soil matrix on the TEGA response. Between 20 and 40 mg of soil, with or without ˜5 mg of lyophilized microorganism biomass (dry weight), were placed in the pyrolyzer and heated from room temperature to 1200 °C in 1 h at a heating rate of 20 °C/min. The volatiles released were transferred to a MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 10 to 200 m/z. In addition, ˜20 mg of each microorganism without a soil matrix were analyzed. As expected, there were significant differences in the gases released from microorganism samples with or without a soil matrix, under similar heating conditions. Furthermore, samples from the most arid environments had significant differences compared with less arid soils. Organic carbon released in the form of CO 2 (ion 44 m/z) from microorganisms evolved at temperatures of ˜326.0 ± 19.5 °C, showing characteristic patterns for each one. Others ions such as 41, 78 and 91 m/z were also found. Interestingly, during the thermal process, the release of CO 2 increased and ions previously found disappeared, demonstrating a high-oxidant activity in the soil matrix when it was subjected to high temperature. Finally, samples of soil show CO 2 evolved up to 650 °C consistent with thermal decomposition of carbonates. These results indicate that organics mixed with these hyperarid soils are oxidized to CO 2. Our results suggest the existence of at least two types of oxidants in these soils, a thermolabile oxidant which is highly oxidative and other thermostable oxidant which has a minor oxidative activity and that survives the heat-treatment. Furthermore, we find that the interaction of biomass added to soil samples gives a different set of breakdown gases than organics resident in the soil. The nature of oxidant(s) present in the soils from Pampas de La Joya is still unknown.

Critical behavior of a relativistic Bose gas.

PubMed

Pandita, P N

2014-03-01

We show that the thermodynamic behavior of relativistic ideal Bose gas, recently studied numerically by Grether et al., can be obtained analytically. Using the analytical results, we obtain the critical behavior of the relativistic Bose gas exactly for all the regimes. We show that these analytical results reduce to those of Grether et al. in different regimes of the Bose gas. Furthermore, we also obtain an analytically closed-form expression for the energy density for the Bose gas that is valid in all regimes.

Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes

NASA Astrophysics Data System (ADS)

Eistrup, Christian; Walsh, Catherine; van Dishoeck, Ewine F.

2018-05-01

Context. Exoplanet atmospheres are thought be built up from accretion of gas as well as pebbles and planetesimals in the midplanes of planet-forming disks. The chemical composition of this material is usually assumed to be unchanged during the disk lifetime. However, chemistry can alter the relative abundances of molecules in this planet-building material. Aims: We aim to assess the impact of disk chemistry during the era of planet formation. This is done by investigating the chemical changes to volatile gases and ices in a protoplanetary disk midplane out to 30 AU for up to 7 Myr, considering a variety of different conditions, including a physical midplane structure that is evolving in time, and also considering two disks with different masses. Methods: An extensive kinetic chemistry gas-grain reaction network was utilised to evolve the abundances of chemical species over time. Two disk midplane ionisation levels (low and high) were explored, as well as two different makeups of the initial abundances ("inheritance" or "reset"). Results: Given a high level of ionisation, chemical evolution in protoplanetary disk midplanes becomes significant after a few times 105 yr, and is still ongoing by 7 Myr between the H2O and the O2 icelines. Inside the H2O iceline, and in the outer, colder regions of the disk midplane outside the O2 iceline, the relative abundances of the species reach (close to) steady state by 7 Myr. Importantly, the changes in the abundances of the major elemental carbon and oxygen-bearing molecules imply that the traditional "stepfunction" for the C/O ratios in gas and ice in the disk midplane (as defined by sharp changes at icelines of H2O, CO2 and CO) evolves over time, and cannot be assumed fixed, with the C/O ratio in the gas even becoming smaller than the C/O ratio in the ice. In addition, at lower temperatures (<29 K), gaseous CO colliding with the grains gets converted into CO2 and other more complex ices, lowering the CO gas abundance between the O2 and CO thermal icelines. This effect can mimic a CO iceline at a higher temperature than suggested by its binding energy. Conclusions: Chemistry in the disk midplane is ionisation-driven, and evolves over time. This affects which molecules go into forming planets and their atmospheres. In order to reliably predict the atmospheric compositions of forming planets, as well as to relate observed atmospheric C/O ratios of exoplanets to where and how the atmospheres have formed in a disk midplane, chemical evolution needs to be considered and implemented into planet formation models.

Nanophase Carbonates on Mars: Does Evolved Gas Analysis of Nanophase Carbonates Reveal a Large Organic Carbon Budget in Near-Surface Martian Materials?

NASA Technical Reports Server (NTRS)

Archer, P. Douglas, Jr.; Niles, Paul B.; Ming, Douglas W.; Sutter, Brad; Eigenbrode, Jen

2015-01-01

Evolved Gas Analysis (EGA), which involves heating a sample and monitoring the gases released, has been performed on Mars by the Viking gas chromatography/mass spectrometry instruments, the Thermal and Evolved Gas Analyzer (TEGA) on the Phoenix lander, and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory. All of these instruments detected CO2 released during sample analysis at abundances of approx. 0.1 to 5 wt% assuming a carbonate source. The source of the CO2 can be constrained by evaluating the temperature of the gas release, a capability of both the TEGA and SAM instruments. The samples analyzed by SAM show that the majority of the CO2 is released below 400C, much lower than traditional carbonate decomposition temperatures which can be as low as 400C for some siderites, with magnesites and calcites decomposing at even higher temperatures. In addition to mineralogy, decomposition temperature can depend on particle size (among other factors). If carbonates formed on Mars under low temperature and relative humidity conditions, the resulting small particle size (nanophase) carbonates could have low decomposition temperatures. We have found that calcite can be synthesized by exposing CaO to water vapor and CO2 and that the resulting mineral has an EGA peak of approx. 550C for CO2, which is about 200C lower than for other calcites. Work is ongoing to produce Fe and Mg-bearing carbonates using the same process. Current results suggest that nanophase calcium carbonates cannot explain the CO2 released from martian samples. If the decomposition temperatures of Mg and Fe-bearing nanophase carbonates are not significantly lower than 400C, other candidate sources include oxalates and carboxylated organic molecules. If present, the abundance of organic carbon in these samples could be greater than 0.1 wt % (1000s of ppm), a signficant departure from the paradigm of the organic-poor Mars based on Viking results.

Thermal and Chemical Characterization of Non-Metallic Materials Using Coupled Thermogravimetric Analysis and Infrared Spectroscopy

NASA Technical Reports Server (NTRS)

Huff, Timothy L.

2002-01-01

Thermogravimetric analysis (TGA) is widely employed in the thermal characterization of non-metallic materials, yielding valuable information on decomposition characteristics of a sample over a wide temperature range. However, a potential wealth of chemical information is lost during the process, with the evolving gases generated during thermal decomposition escaping through the exhaust line. Fourier Transform-Infrared spectroscopy (FT-IR) is a powerful analytical technique for determining many chemical constituents while in any material state, in this application, the gas phase. By linking these two techniques, evolving gases generated during the TGA process are directed into an appropriately equipped infrared spectrometer for chemical speciation. Consequently, both thermal decomposition and chemical characterization of a material may be obtained in a single sample run. In practice, a heated transfer line is employed to connect the two instruments while a purge gas stream directs the evolving gases into the FT-IR. The purge gas can be either high purity air or an inert gas such as nitrogen to allow oxidative and pyrolytic processes to be examined, respectively. The FT-IR data is collected realtime, allowing continuous monitoring of chemical compositional changes over the course of thermal decomposition. Using this coupled technique, an array of diverse materials has been examined, including composites, plastics, rubber, fiberglass epoxy resins, polycarbonates, silicones, lubricants and fluorocarbon materials. The benefit of combining these two methodologies is of particular importance in the aerospace community, where newly developing materials have little available data with which to refer. By providing both thermal and chemical data simultaneously, a more definitive and comprehensive characterization of the material is possible. Additionally, this procedure has been found to be a viable screening technique for certain materials, with the generated data useful in the selection of other appropriate analytical procedures for further material characterization.

Characteristic Study of Some Different Kinds of Coal Particles Combustion with Online TG-MS-FTIR

NASA Astrophysics Data System (ADS)

Pan, Guanfu

2018-01-01

Four kinds of pulverized coal samples from China and Indonesia were studied by thermogravimetry coupled with mass spectrometry and fourier transform infrared spectroscopy (TG-MS-FTIR). The thermal behaviors and gaseous emissions of these coals were analyzed in this work. The results indicate that the relative lower values of H/C ratios, which normally represent the degree of aromatization and ring condensation in coal samples, could lead to the relative more intense thermal reaction. The time-evolved profiles of some typical gas products (i.e., CO, SO2, CH4, NO, NO2, NH3 and etc.) were provided by TG-MS-FTIR, and their variations are different. For all the samples, the releases of SO2 and COS can be found at lower temperature than those of NO and CO. As the temperature increases, the possible conversion of NO2 and NH3 to NO is deduced in this work.

TEGA Whirligig Model

NASA Image and Video Library

2008-06-09

This is a photo of an engineering model of the Thermal and Evolved-Gas Analyzer TEGA instrument on board NASA Phoenix Mars Lander. This view shows a TEGA oven-loading mechanism beneath the input screen.

Molecular Cloud Structures and Massive Star Formation in N159

NASA Astrophysics Data System (ADS)

Nayak, O.; Meixner, M.; Fukui, Y.; Tachihara, K.; Onishi, T.; Saigo, K.; Tokuda, K.; Harada, R.

2018-02-01

The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the 12CO, 13CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size–linewidth relation than the 12CO or 13CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the 13CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501 M ⊙ pc‑2, and the threshold for massive star formation in N159E is 794 M ⊙ pc‑2. We find that 13CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.

Behaviors of cavefish offer insight into developmental evolution

PubMed Central

2015-01-01

SUMMARY Many developmental processes have evolved through natural selection, yet in only a few cases do we understand if and how a change of developmental process produces a benefit. For example, many studies in evolutionary biology have investigated the developmental mechanisms that lead to novel structures in an animal, but only a few have addressed if these structures actually benefit the animal at the behavioral level of prey hunting and mating. As such, this review discusses an animal's behavior as the integrated functional output of its evolved morphological and physiological traits. Specifically, we focus on recent findings about the blind Mexican cavefish, Astyanax mexicanus, for which clear relationships exist between its physical traits and ecosystem. This species includes two morphotypes: an eyed surface dweller versus many conspecific types of blind cave dwellers, some of which evolved independently; all of the blind subtypes derived from eyed surface dwellers. The blind cavefish evolved under clear selection pressures: food is sparse and darkness is perpetual. Simulating the major aspects of a cave ecosystem in the laboratory is relatively easy, so we can use this species to begin resolving the relationships between evolved traits and selection pressures—relationships which are more complex for other animals models. This review discusses the recent advances in cavefish research that have helped us establish some key relationships between morphological evolution and environmental shifts. Mol. Reprod. Dev. 82: 268–280, 2015. © 2015 Wiley Periodicals, Inc. PMID:25728684

A theory for the evolution of other-regard integrating proximate and ultimate perspectives.

PubMed

Akçay, Erol; Van Cleve, Jeremy; Feldman, Marcus W; Roughgarden, Joan

2009-11-10

Although much previous work describes evolutionary mechanisms that promote or stabilize different social behaviors, we still have little understanding of the factors that drive animal behavior proximately. Here we present a modeling approach to answer this question. Our model rests on motivations to achieve objectives as the proximate determinants of behavior. We develop a two-tiered framework by first modeling the dynamics of a social interaction at the behavioral time scale and then find the evolutionarily stable objectives that result from the outcomes these dynamics produce. We use this framework to ask whether "other-regarding" motivations, which result from a kind of nonselfish objective, can evolve when individuals are engaged in a social interaction that entails a conflict between their material payoffs. We find that, at the evolutionarily stable state, individuals can be other-regarding in that they are motivated to increase their partners' payoff as well as their own. In contrast to previous theories, we find that such motivations can evolve because of their direct effect on fitness and do not require kin selection or a special group structure. We also derive general conditions for the evolutionary stability of other-regarding motivations. Our conditions indicate that other-regarding motivations are more likely to evolve when social interactions and behavioral objectives are both synergistic.

Integrating the Human Sciences to Evolve Effective Policies

PubMed Central

Biglan, Anthony; Cody, Christine

2012-01-01

This paper describes an evolutionary perspective on human development and wellbeing and contrasts it with the model of self-interest that is prominent in economics. The two approaches have considerably different implications for how human wellbeing might be improved. Research in psychology, prevention science, and neuroscience is converging on an evolutionary account of the importance of two contrasting suites of social behavior—prosociality vs. antisocial behaviors (crime, drug abuse, risky sexual behavior) and related problems such as depression. Prosociality of individuals and groups evolves in environments that minimize toxic biological and social conditions, promote and richly reinforce prosocial behavior and attitudes, limit opportunities for antisocial behavior, and nurture the pursuit of prosocial values. Conversely, antisocial behavior and related problems emerge in environments that are high in threat and conflict. Over the past 30 years, randomized trials have shown numerous family, school, and community interventions to prevent most problem behaviors and promote prosociality. Research has also shown that poverty and economic inequality are major risk factors for the development of problem behaviors. The paper describes policies that can reduce poverty and benefit youth development. Although it is clear that the canonical economic model of rational self-interest has made a significant contribution to the science of economics, the evidence reviewed here shows that it must be reconciled with an evolutionary perspective on human development and wellbeing if society is going to evolve public policies that advance the health and wellbeing of the entire population. PMID:23833332

Infrared Observations of Hot Gas and Cold Ice Toward the Low Mass Protostar Elias 29

NASA Technical Reports Server (NTRS)

Boogert, A. C. A.; Tielens, A. G. G. M.; Ceccarelli, C.; Boonman, A. M. S.; vanDishoeck, E. F.; Keane, J. V.; Whittet, D. C. B.; deGraauw, T.

2000-01-01

We have obtained the full 1-200 micrometer spectrum of the low luminosity (36 solar luminosity Class I protostar Elias 29 in the rho Ophiuchi molecular cloud. It provides a unique opportunity to study the origin and evolution of interstellar ice and the interrelationship of interstellar ice and hot core gases around low mass protostars. We see abundant hot CO and H2O gas, as well as the absorption bands of CO, CO2, H2O and "6.85 micrometer" ices. We compare the abundances and physical conditions of the gas and ices toward Elias 29 with the conditions around several well studied luminous, high mass protostars. The high gas temperature and gas/solid ratios resemble those of relatively evolved high mass objects (e.g. GL 2591). However, none of the ice band profiles shows evidence for significant thermal processing, and in this respect Elias 29 resembles the least evolved luminous protostars, such as NGC 7538 : IRS9. Thus we conclude that the heating of the envelope of the low mass object Elias 29 is qualitatively different from that of high mass protostars. This is possibly related to a different density gradient of the envelope or shielding of the ices in a circumstellar disk. This result is important for our understanding of the evolution of interstellar ices, and their relation to cometary ices.

Gas flow through rough microchannels in the transition flow regime.

PubMed

Deng, Zilong; Chen, Yongping; Shao, Chenxi

2016-01-01

A multiple-relaxation-time lattice Boltzmann model of Couette flow is developed to investigate the rarified gas flow through microchannels with roughness characterized by fractal geometry, especially to elucidate the coupled effects of roughness and rarefaction on microscale gas flow in the transition flow regime. The results indicate that the surface roughness effect on gas flow behavior becomes more significant in rarefied gas flow with the increase of Knudsen number. We find the gas flow behavior in the transition flow regime is more sensitive to roughness height than that in the slip flow regime. In particular, the influence of fractal dimension on rarefied gas flow behavior is less significant than roughness height.

A Panchromatic Study of Molecular Gas in the Protoplanetary System RY Lupi

NASA Astrophysics Data System (ADS)

Arulanantham, Nicole; France, Kevin; Hoadley, Keri

2018-01-01

To understand how planet formation occurs in protoplanetary disks, we must first characterize the behavior of material within 10 AU of the central star. We present a study of molecular gas at these radii in the disk around the young star RY Lupi, through spectra from HST-COS, HST-STIS, and VLT-CRIRES. We model the radial distribution of flux from hot (T ~ 2000 K) molecular gas in a surface layer between r = 0.1-10 AU, as traced by LyA-pumped H2. The result indicates that the H2 emission originates in a narrow ring centered at 1 AU, with a sharp decline in flux at r < 0.1 AU that is consistent with what is expected for transitional disks. When we adopt a more basic approach to evaulate the shapes of the emission lines, we find that a two-component Gaussian profile assuming two rings of gas in the inner disk provides a statistically better fit to the H2 emission lines than the single-component model of a smooth disk. This two-component profile includes broad (FWHMbroad, H2 = 105 +/- 15 km/s) and narrow (FWHMnarrow, H2 = 43 +/- 13 km/s) lines, corresponding to average gas radii of ~ 0.4 AU and ~ 3 AU. An analysis of the spatial origin of 4.7 micron 12CO emission shows that this population of warm (T ~ 1500 K) gas also produces two-component emission line profiles ( ~ 0.4 AU, ~ 15 AU), indicating again that the inner disk is radially stratified. Despite the evidence that this is a transitional disk system, we detect UV CO absorption that is not typically seen in more evolved systems. We model these features along with IR CO absorptions to constrain the properties of the cooler (T ~ 100-300 K) disk atmosphere.

Laboratory Evolved Gas Analyses of Si-rich Amorphous Materials: Implications for Analyses of Si-rich Amorphous Material in Gale Crater by the Mars Science Laboratory Sample Analysis at Mars Instrument

NASA Astrophysics Data System (ADS)

McAdam, A.; Knudson, C. A.; Sutter, B.; Andrejkovicova, S. C.; Archer, P. D., Jr.; Franz, H. B.; Eigenbrode, J. L.; Morris, R. V.; Ming, D. W.; Sun, V. Z.; Milliken, R.; Wilhelm, M. B.; Mahaffy, P. R.; Navarro-Gonzalez, R.

2016-12-01

The Chemistry and Mineralogy (CheMin) instrument onboard the Mars Science Laboratory (MSL) rover detected Si-rich amorphous or poorly ordered materials in several samples from Murray Formation mudstones and Stimson Formation sandstones. High-SiO2 amorphous materials such as opal-A or rhyolitic glass are candidate phases, but CheMin data cannot be used to distinguish between these possibilities. In the Buckskin (BS) sample from the upper Murray Formation, and the Big Sky (BY) and Greenhorn (GH) samples from the Stimson Formation, evolved gas analyses by the Sample Analysis at Mars (SAM) instrument showed very broad H2O evolutions during sample heating at temperatures >450-500°C, which had not been observed from previous samples. BS also had a significant broad evolution <450-500°C. We have undertaken a laboratory study targeted at understanding if the data from SAM analyses can be used to place constraints on the nature of the amorphous phases. SAM-like evolved gas analyses have been performed on several opal and rhyolitic glass samples. Opal-A samples exhibited wide <500°C H2O evolutions, with lesser H2O evolved above 500°C. H2O evolution traces from rhyolitic glasses varied, having either two broad H2O peaks, <300°C and >500°C, or a broad peak centered around 400°C. For samples that produced two evolutions, the lower temperature peak was more intense than the higher temperature peak, a trend also exhibited by opal-A. This trend is consistent with data from BS, but does not seem consistent with data from BY and GH which evolved most of their H2O >500°C. It may be that dehydration of opal-A and/or rhyolitic glass can result in some preferential loss of lower temperature H2O, to produce traces that more closely resemble BY and GH. This is currently under investigation and results will be reported.

Small groups and long memories promote cooperation.

PubMed

Stewart, Alexander J; Plotkin, Joshua B

2016-06-01

Complex social behaviors lie at the heart of many of the challenges facing evolutionary biology, sociology, economics, and beyond. For evolutionary biologists the question is often how group behaviors such as collective action, or decision making that accounts for memories of past experience, can emerge and persist in an evolving system. Evolutionary game theory provides a framework for formalizing these questions and admitting them to rigorous study. Here we develop such a framework to study the evolution of sustained collective action in multi-player public-goods games, in which players have arbitrarily long memories of prior rounds of play and can react to their experience in an arbitrary way. We construct a coordinate system for memory-m strategies in iterated n-player games that permits us to characterize all cooperative strategies that resist invasion by any mutant strategy, and stabilize cooperative behavior. We show that, especially when groups are small, longer-memory strategies make cooperation easier to evolve, by increasing the number of ways to stabilize cooperation. We also explore the co-evolution of behavior and memory. We find that even when memory has a cost, longer-memory strategies often evolve, which in turn drives the evolution of cooperation, even when the benefits for cooperation are low.

Individual behavior, culture, and social change

PubMed Central

Glenn, Sigrid S.

2004-01-01

The principle of operant selection is examined as a prototype of cultural selection, and the role of the social environment is suggested as the critical element in the emergence of cultural phenomena. Operant contingencies are compared to cultural selection contingencies, designated as metacontingencies. Both of these types of contingency relations result in evolving lineages of recurrences that can become increasingly complex in the number and organization of their elements. In addition to its role in the recurring interlocking behavioral contingencies that constitute cultural organization, operant behavior plays another role in cultures. Although the operants of individuals are functionally independent of one another, the behavior of each person may contribute to a cumulative effect that is relevant to the well-being of many people. Similarly, the outcomes of metacontingencies may also contribute to a cumulative effect. The relation between independently evolving operant lineages, or between independently evolving cultural lineages, and their cumulative effect is identified as a macrocontingency. Macrocontingencies do not involve cultural-level selection per se. Effective cultural engineering requires identifying the macrocontingencies that produce less than desirable effects and altering the relevant operant contingencies or metacontingencies to produce change in the cumulative effects. PMID:22478424

Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots.

PubMed

Duarte, Miguel; Costa, Vasco; Gomes, Jorge; Rodrigues, Tiago; Silva, Fernando; Oliveira, Sancho Moura; Christensen, Anders Lyhne

2016-01-01

Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers.

Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots

PubMed Central

Duarte, Miguel; Costa, Vasco; Gomes, Jorge; Rodrigues, Tiago; Silva, Fernando; Oliveira, Sancho Moura; Christensen, Anders Lyhne

2016-01-01

Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers. PMID:26999614

Superfluid density of states and pseudogap phenomenon in the BCS-BEC crossover regime of a superfluid Fermi gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watanabe, Ryota; Tsuchiya, Shunji; CREST

2010-10-15

We investigate single-particle excitations and strong-coupling effects in the BCS-BEC crossover regime of a superfluid Fermi gas. Including phase and amplitude fluctuations of the superfluid order parameter within a T-matrix theory, we calculate the superfluid density of states (DOS), as well as single-particle spectral weight, over the entire BCS-BEC crossover region below the superfluid transition temperature T{sub c}. We clarify how the pseudogap in the normal state evolves into the superfluid gap, as one passes through T{sub c}. While the pseudogap in DOS continuously evolves into the superfluid gap in the weak-coupling BCS regime, the superfluid gap in the crossovermore » region is shown to appear in DOS after the pseudogap disappears below T{sub c}. In the phase diagram with respect to the temperature and interaction strength, we determine the region where strong pairing fluctuations dominate over single-particle properties of the system. Our results would be useful for the study of strong-coupling phenomena in the BCS-BEC crossover regime of a superfluid Fermi gas.« less

Extreme events in a vortex gas simulation of a turbulent half-jet

NASA Astrophysics Data System (ADS)

Suryanarayanan, Saikishan; Pathikonda, Gokul; Narasimha, Roddam

2012-11-01

Extensive simulations [arXiv:1008.2876v1 [physics.flu-dyn], BAPS.2010.DFD.LE.4] have shown that the temporally evolving vortex gas mixing layer has 3 regimes, including one which has a universal spreading rate. The present study explores the development of spatially evolving mixing layers, using a vortex gas model based on Basu et al. (1995 Appl. Math. Modelling). The effects of the velocity ratio (r) are analyzed via the most extensive simulations of this kind till date, involving up to 10000 vortices and averaging over up to 1000 convective times. While the temporal limit is approached as r approaches unity, striking features such as extreme events involving coherent structures, bending, deviation of the convection velocity from mean velocity, spatial feedback and greater sensitivity to downstream and free stream boundary conditions are observed in the half-jet (r = 0) limit. A detailed statistical analysis reveals possible causes for the large scatter across experiments, as opposed to the commonly adopted explanation of asymptotic dependence on initial conditions. Supported in part by contract no. Intel/RN/4288.

Chemical alarm in the termite Termitogeton planus (Rhinotermitidae).

PubMed

Dolejšová, Klára; Krasulová, Jana; Kutalová, Kateřina; Hanus, Robert

2014-12-01

Effective defense is a common characteristic of insect societies. Indeed, the occurrence of specialized defenders, soldiers, has been the first step toward eusociality in several independent lineages, including termites. Among the multitude of defensive strategies used by termite soldiers, defense by chemicals plays a crucial role. It has evolved with complexity in advanced isopteran lineages, whose soldiers are equipped with a unique defensive organ, the frontal gland. Besides direct defense against predators, competitors, and pathogens, the chemicals emitted by soldiers from the frontal gland are used as signals of alarm. In this study, we investigated the chemical composition of the defensive secretion produced by soldiers of the termite Termitogeton planus (Isoptera: Rhinotermitidae), from West Papua, and the effects of this secretion on the behavior of termite groups. Detailed two-dimensional gas chromatography/mass spectrometry analyses of the soldier defensive secretion revealed the presence of four linear and nine monoterpene hydrocarbons. Soldier head extracts, as well as synthetic mixtures of the monoterpenes found in these extracts, elicited alarm behavior in both soldiers and pseudergates. Our results suggest that the alarm is not triggered by a single monoterpene from the defensive blend, but by a multi-component signal combining quantitatively major and minor compounds.

Spectral Behavior of Weakly Compressible Aero-Optical Distortions

NASA Astrophysics Data System (ADS)

Mathews, Edwin; Wang, Kan; Wang, Meng; Jumper, Eric

2016-11-01

In classical theories of optical distortions by atmospheric turbulence, an appropriate and key assumption is that index-of-refraction variations are dominated by fluctuations in temperature and the effects of turbulent pressure fluctuations are negligible. This assumption is, however, not generally valid for aero-optical distortions caused by turbulent flow over an optical aperture, where both temperature and pressures fluctuations may contribute significantly to the index-of-refraction fluctuations. A general expression for weak fluctuations in refractive index is derived using the ideal gas law and Gladstone-Dale relation and applied to describe the spectral behavior of aero-optical distortions. Large-eddy simulations of weakly compressible, temporally evolving shear layers are then used to verify the theoretical results. Computational results support theoretical findings and confirm that if the log slope of the 1-D density spectrum in the inertial range is -mρ , the optical phase distortion spectral slope is given by - (mρ + 1) . The value of mρ is then shown to be dependent on the ratio of shear-layer free-stream densities and bounded by the spectral slopes of temperature and pressure fluctuations. Supported by HEL-JTO through AFOSR Grant FA9550-13-1-0001 and Blue Waters Graduate Fellowship Program.

Movie of phase separation during physics of colloids in space experiment

NASA Technical Reports Server (NTRS)

2002-01-01

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area in the video is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Phase separation during the Experiment on Physics of Colloids in Space

NASA Technical Reports Server (NTRS)

2003-01-01

Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

Effects of Vertex Activity and Self-organized Criticality Behavior on a Weighted Evolving Network

NASA Astrophysics Data System (ADS)

Zhang, Gui-Qing; Yang, Qiu-Ying; Chen, Tian-Lun

2008-08-01

Effects of vertex activity have been analyzed on a weighted evolving network. The network is characterized by the probability distribution of vertex strength, each edge weight and evolution of the strength of vertices with different vertex activities. The model exhibits self-organized criticality behavior. The probability distribution of avalanche size for different network sizes is also shown. In addition, there is a power law relation between the size and the duration of an avalanche and the average of avalanche size has been studied for different vertex activities.

The History of Behavioral Treatments in Autism: From the Punitive to the Positive

ERIC Educational Resources Information Center

Suppo, Jennifer L.

2017-01-01

The behavioral treatments for persons diagnosed with autism have evolved from those that included punitive components to those that are now based upon principles of positive behavior supports. The proceeding document provides an historical overview of relevant behavioral approaches, including the type of approach and the quality of involvement and…

The Evolution of Oscillatory Behavior during Learning on a Ski Simulator

ERIC Educational Resources Information Center

Teulier, Caroline; Nourrit, Deborah; Delignieres, Didier

2006-01-01

Recent experiments on the ski simulator produced ambiguous results and raised unanswered questions concerning the true nature of "novice" behavior and the occurrence of behavioral changes during learning. The aim of the present experiment was to analyze the evolving behavior of three beginners during six practice sessions on a ski simulator. The…

Student Test Performances on Behavior of Gas Particles and Mismatch of Teacher Predictions

ERIC Educational Resources Information Center

Liang, Jia-Chi; Chou, Chin-Cheng; Chiu, Mei-Hung

2011-01-01

The nature and behavior of gas particles are essential concepts in teaching and learning of school chemistry. However, findings about students' understanding of gas particles--their composition, structure, and interactions involving movement and distribution--revealed that the difficulties students encounter in understanding gas particles vary…

Automated soil gas monitoring chamber

DOEpatents

Edwards, Nelson T.; Riggs, Jeffery S.

2003-07-29

A chamber for trapping soil gases as they evolve from the soil without disturbance to the soil and to the natural microclimate within the chamber has been invented. The chamber opens between measurements and therefore does not alter the metabolic processes that influence soil gas efflux rates. A multiple chamber system provides for repetitive multi-point sampling, undisturbed metabolic soil processes between sampling, and an essentially airtight sampling chamber operating at ambient pressure.

Method and apparatus for controlling gas evolution from chemical reactions

DOEpatents

Skorpik, James R.; Dodson, Michael G.

1999-01-01

The present invention is directed toward monitoring a thermally driven gas evolving chemical reaction with an acoustic apparatus. Signals from the acoustic apparatus are used to control a heater to prevent a run-away condition. A digestion module in combination with a robotic arm further automate physical handling of sample material reaction vessels. The invention is especially useful for carrying out sample procedures defined in EPA Methods SW-846.

The physical and chemical evolution of disks during planet formation

NASA Astrophysics Data System (ADS)

Gorti, Uma

2018-06-01

Protoplanetary disks evolve and disperse rapidly during the early stages of star and planet formation. While disks initially inherit a full complement of interstellar cloud material that is mainly accreted on to the central star, their gas and dust components appear to evolve along distinct pathways. Dust accumulates to form rocky planets, whereas only a small fraction of the available gas may be incorporated into gas giants in a typical exoplanetary system. However, the radial distribution of gas and its chemistry are expected to impact the architecture and composition of formed planets. Recent ALMA results have underscored the importance of ices and grain surface chemistry in disks, and their significance for planet formation. I will describe disk models that aim to probe the physical and chemical processes in the disk at various stages of evolution, and specifically discuss diagnostics of conditions in the innermost regions of disks which will become accessible for the first time with the launch of JWST. Current theoretical modeling is however hindered by many uncertainties in input parameters and poorly known chemical and physical processes. I will highlight some gaps in our current understanding, and discuss how laboratory astrophysics can help in preparing for the JWST era and aid in the interpretation of future line and continuum emission studies.

Cognitive-Developmental and Behavior-Analytic Theories: Evolving into Complementarity

ERIC Educational Resources Information Center

Overton, Willis F.; Ennis, Michelle D.

2006-01-01

Historically, cognitive-developmental and behavior-analytic approaches to the study of human behavior change and development have been presented as incompatible alternative theoretical and methodological perspectives. This presumed incompatibility has been understood as arising from divergent sets of metatheoretical assumptions that take the form…

Evolved differences in larval social behavior mediated by novel pheromones

USDA-ARS?s Scientific Manuscript database

Pheromones, chemical signals that convey social information, mediate many insect social behaviors in both adult and immature stages. Multiple pheromones and neural pathways that underlie adult social behavior have been described in the genetic model organism, Drosophila melanogaster, but there is no...

Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition

PubMed Central

Prior, Helmut; Schwarz, Ariane; Güntürkün, Onur

2008-01-01

Comparative studies suggest that at least some bird species have evolved mental skills similar to those found in humans and apes. This is indicated by feats such as tool use, episodic-like memory, and the ability to use one's own experience in predicting the behavior of conspecifics. It is, however, not yet clear whether these skills are accompanied by an understanding of the self. In apes, self-directed behavior in response to a mirror has been taken as evidence of self-recognition. We investigated mirror-induced behavior in the magpie, a songbird species from the crow family. As in apes, some individuals behaved in front of the mirror as if they were testing behavioral contingencies. When provided with a mark, magpies showed spontaneous mark-directed behavior. Our findings provide the first evidence of mirror self-recognition in a non-mammalian species. They suggest that essential components of human self-recognition have evolved independently in different vertebrate classes with a separate evolutionary history. PMID:18715117

On the Evolution of Behaviors through Embodied Imitation.

PubMed

Erbas, Mehmet D; Bull, Larry; Winfield, Alan F T

2015-01-01

This article describes research in which embodied imitation and behavioral adaptation are investigated in collective robotics. We model social learning in artificial agents with real robots. The robots are able to observe and learn each others' movement patterns using their on-board sensors only, so that imitation is embodied. We show that the variations that arise from embodiment allow certain behaviors that are better adapted to the process of imitation to emerge and evolve during multiple cycles of imitation. As these behaviors are more robust to uncertainties in the real robots' sensors and actuators, they can be learned by other members of the collective with higher fidelity. Three different types of learned-behavior memory have been experimentally tested to investigate the effect of memory capacity on the evolution of movement patterns, and results show that as the movement patterns evolve through multiple cycles of imitation, selection, and variation, the robots are able to, in a sense, agree on the structure of the behaviors that are imitated.

Effortful Control, Explicit Processing, and the Regulation of Human Evolved Predispositions

ERIC Educational Resources Information Center

MacDonald, Kevin B.

2008-01-01

This article analyzes the effortful control of automatic processing related to social and emotional behavior, including control over evolved modules designed to solve problems of survival and reproduction that were recurrent over evolutionary time. The inputs to effortful control mechanisms include a wide range of nonrecurrent…

Can knowledge of developmental processes illuminate the evolution of parental care?

PubMed

Michel, George F; Tyler, Amber N

2007-01-01

There are two levels of investigation for elucidating the evolution of parental behavior. The macro level focuses on how parental behavior can evolve as an aspect of reproduction. The micro level focuses on how species variations in parental behavior evolve. Recently, modern evolutionary biology has turned to developmental biology as a source for information about how trait variability (the substrate upon which natural selection and other evolutionary mechanisms can operate) can emerge during development (called "evo-devo"). Application of this evo-devo approach to the phenomenon of parental behavior requires identification of those mechanisms that produce variations in developmental pathways leading to parental behavior. It is these variations that provide the phenotypes for the potential evolution of different parental behavior systems. Variations in rodent maternal behavior affect the development of the HPA and HPG axes in their offspring. These mechanisms are examined to reveal how such developmental variations could underlie the evolution of biparental behavior. Knowledge of the developmental mechanisms responsible for species variations in mammalian parental behavior systems may provide insight into those mechanisms that may have been involved in the evolution of parental behavior itself. Copyright (c) 2006 Wiley Periodicals, Inc.

Evolution of Multiple Sensory Systems Drives Novel Egg-Laying Behavior in the Fruit Pest Drosophila suzukii.

PubMed

Karageorgi, Marianthi; Bräcker, Lasse B; Lebreton, Sébastien; Minervino, Caroline; Cavey, Matthieu; Siju, K P; Grunwald Kadow, Ilona C; Gompel, Nicolas; Prud'homme, Benjamin

2017-03-20

The rise of a pest species represents a unique opportunity to address how species evolve new behaviors and adapt to novel ecological niches [1]. We address this question by studying the egg-laying behavior of Drosophila suzukii, an invasive agricultural pest species that has spread from Southeast Asia to Europe and North America in the last decade [2]. While most closely related Drosophila species lay their eggs on decaying plant substrates, D. suzukii oviposits on ripening fruit, thereby causing substantial economic losses to the fruit industry [3-8]. D. suzukii has evolved an enlarged, serrated ovipositor that presumably plays a key role by enabling females to pierce the skin of ripe fruit [9]. Here, we explore how D. suzukii selects oviposition sites, and how this behavior differs from that of closely related species. We have combined behavioral experiments in multiple species with neurogenetics and mutant analysis in D. suzukii to show that this species has evolved a specific preference for oviposition on ripe fruit. Our results also establish that changes in mechanosensation, olfaction, and presumably gustation have contributed to this ecological shift. Our observations support a model in which the emergence of D. suzukii as an agricultural pest is the consequence of the progressive modification of several sensory systems, which collectively underlie a radical change in oviposition behavior. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Child abuse and the balance of power in parental relationships: an evolved domain-independent mental mechanism that accounts for behavioral variation.

PubMed

Handwerker, W P

2001-01-01

Previous studies use zero-order analyses to show a link between child abuse and exposure to "stepfathers." These studies rest on a proposed evolved, domain-specific cognitive mechanism that induces adult males to abuse or kill offspring not their own and, so, contribute directly to reproductive success. However, child abuse may reflect an evolved neurological mechanism that creates behavioral plasticity and adaptability by assigning emotional weights (which in consciousness appear rationalized as costs and benefits) to choice alternatives in all behavioral domains. This mechanism should act as a selective mechanism to create enhanced ability to avoid predation (social exploitation) and to obtain access to resources, given the properties of specific ecosystems, and should control behavioral responses to variation in the balance of power in social relationships. Power equalities should elicit good treatment for both parties; power inequalities, by contrast, should elicit exploitative and coercive behavior on the part of those who hold the balance of power. This paper reports a test of both hypotheses simultaneously, controlling for a standard social science risk factor (growing up in poverty). Once we control for the balance of power in parental relationships, exposure to a stepfather and growing up in poverty show no effect on the intensity of child abuse. Powerful women negotiated affectionate behavior from their partners for both themselves and their children; powerless women's negotiations with partners usually left both themselves and their children open to violence.

Oxidant activity in hyperarid soils from Atacama Desert in southern Peru, under conditions of the labeled release and thermal evolved gas analysis experiments: Implications for the search of organic matter on Mars

NASA Astrophysics Data System (ADS)

Valdivia-Silva, Julio E.; Navarro-Gonzalez, Rafael; McKay, Chris

Thermal evolved gas analysis (TEGA), one of several instruments on board of the Phoenix Lander, is a combination of a high temperature furnace and a mass spectrometer that was used to analyze Mars soil samples heated at a programmed ramp rate up to 1000 ° C. The evolved gases generated during the process were analyzed with the evolved gas analyzer (a mass spectrometer) in order to determine the composition of gases released as a function of temperature. In other hand, labeled release experiment (LR), one of the Viking biology anal-ysis used on Mars, monitored the radioactive gas evolution after the addition of a 14C-labeled aqueous organic substrate into a sealed test cell that contained a Martian surface sample. This experiment was designed to test Martian surface samples for the presence of life by measuring metabolic activity and distinguishing it from physical or chemical activity. The interpretation of the Viking LR experiment was that the tested soils were chemically reactive and not biolog-ically active, and that at least two oxidative processes with different kinetics were required to explain the observed decomposition of organics, while TEGA experiment of the Phoenix mis-sion apparently didn't detect organic matter on the surface of Mars. Both of these experiments showed little possibility of the presence of organics, and therefore the presence of life. Here we examine the evolved gas properties of hyperarid soils from the Pampas de La Joya, which is considered as a new analogue to Mars, in order to investigate the effect of the soil matrix on the TEGA response, and additionally, we conducted experiments under Viking LR protocol to test the decomposition kinetics of organic compounds in aqueous solution added to these soils. Our TEGA results indicate that native or added organics present in these samples were oxidized to CO2 during thermal process, suggesting the existence in these soils of a thermolabile oxidant which is highly oxidative and other thermostable oxidant which has a minor oxidative activity and that survives the heat-treatment. Interestingly, LR experiment shows that the 13C-labeled formate and DL-alanine were oxidized to 13CO2 when added in aqueous solution to soils collected from the Pampas de La Joya region. The observation of similar 13CO2 initial releasing by soils treated with L-alanine, compared to soils treated D-alanine, indicates the presence of one or more nonbiological chemical decomposition mechanisms similar to Yungay soils and the Viking LR experiment. Thus, the soils from Pampas of La Joya, are potentially excellent analogues of the oxidative processes that occur on Mars, and can be used to study mechanisms of destruction of organics on this planet. The nature of oxidant(s) present in the soils from Pampas de La Joya is still unknown.

Molecules in the transition disk orbiting T Chamaeleontis

NASA Astrophysics Data System (ADS)

Sacco, G. G.; Kastner, J. H.; Forveille, T.; Principe, D.; Montez, R.; Zuckerman, B.; Hily-Blant, P.

2014-01-01

Aims: We seek to establish the presence and properties of gas in the circumstellar disk orbiting T Cha, a nearby (d ~ 110 pc), relatively evolved (age ~5-7 Myr) yet actively accreting 1.5 M⊙ T Tauri star. Methods: We used the Atacama Pathfinder Experiment (APEX) 12 m radiotelescope to search for submillimeter molecular emission from the T Cha disk, and we reanalyzed archival XMM-Newton imaging spectroscopy of T Cha to ascertain the intervening absorption due to disk gas along the line of sight to the star (NH). Results: We detected submillimeter rotational transitions of 12CO, 13CO, HCN, CN, and HCO+ from the T Cha disk. The 12CO line (and possibly the 13CO line) appears to display a double-peaked line profile indicative of Keplerian rotation; hence, these molecular line observations constitute the first direct demonstration of the presence of cold molecular gas orbiting T Cha. Analysis of the CO emission line data indicates that the disk around T Cha has a mass (Mdisk,H2 = 80 M⊕) similar to, but more compact (Rdisk,CO ~ 80 AU) than other nearby, evolved molecular disks (e.g., V4046 Sgr, TW Hya, MP Mus) in which cold molecular gas has been previously detected. The HCO+/13CO and HCN/13CO line ratios measured for T Cha appear similar to those of other evolved circumstellar disks (i.e., TW Hya and V4046 Sgr). The CN/13CO ratio appears somewhat weaker, but due to the low signal-to-noise ratio of our detection, this discrepancy is not strongly significant. Analysis of the XMM-Newton X-ray spectroscopic data shows that the atomic absorption NH toward T Cha is one to two orders of magnitude larger than toward the other nearby T Tauri with evolved disks, which are seen at much lower inclination angles. Furthermore, the ratio between atomic absorption and optical extinction NH/AV toward T Cha is higher than the typical value observed for the interstellar medium and young stellar objects in the Orion nebula cluster. This may suggest that the fraction of metals in the disk gas is higher than in the interstellar medium. However, an X-ray absorption model appropriate for the physical and chemical conditions of a circumstellar disk is required to address this issue. Conclusions: Our results confirm that pre-main-sequence stars older than ~5 Myr retain cold molecular disks when accreting, and that those relatively evolved disks display similar physical and chemical properties. Based on submillimeter and X-ray observations. Submillimeter observations have been collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, with the Atacama Pathfinder Experiment APEX (Prog. ID 088.C-0441 and E-089.C-0518A). X-ray archival observations used in this paper have been obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.

Diffusion reordering kinetics in lattice-gas systems: Time evolution of configurational entropy and internal energy

NASA Astrophysics Data System (ADS)

Weinketz, Sieghard

1998-07-01

The reordering kinetics of a diffusion lattice-gas system of adsorbates with nearest- and next-nearest-neighbor interactions on a square lattice is studied within a dynamic Monte Carlo simulation, as it evolves towards the equilibrium from a given initial configuration, at a constant temperature. The diffusion kinetics proceeds through adsorbate hoppings to empty nearest-neighboring sites (Kawasaki dynamics). The Monte Carlo procedure allows a ``real'' time definition from the local transition rates, and the configurational entropy and internal energy can be obtained from the lattice configuration at any instant t by counting the local clusters and using the C2 approximation of the cluster variation method. These state functions are then used in their nonequilibrium form as a direct measure of reordering along the time. Different reordering processes are analyzed within this approach, presenting a rich variety of behaviors. It can also be shown that the time derivative of entropy (times temperature) is always equal to or lower than the time derivative of energy, and that the reordering path is always strongly dependent on the initial order, presenting in some cases an ``invariance'' of the entropy function to the magnitude of the interactions as far as the final order is unaltered.

Tapered Glass-Fiber Microspike: High-Q Flexural Wave Resonator and Optically Driven Knudsen Pump.

PubMed

Pennetta, Riccardo; Xie, Shangran; Russell, Philip St J

2016-12-30

Appropriately designed optomechanical devices are ideal for making ultra-sensitive measurements. Here we report a fused-silica microspike that supports a flexural resonance with a quality factor greater than 100 000 at room temperature in vacuum. Fashioned by tapering single-mode fiber (SMF), it is designed so that the core-guided optical mode in the SMF evolves adiabatically into the fundamental mode of the air-glass waveguide at the tip. The very narrow mechanical linewidth (20 mHz) makes it possible to measure extremely small changes in resonant frequency. In a vacuum chamber at low pressure, the weak optical absorption of the glass is sufficient to create a temperature gradient along the microspike, which causes it to act as a microscopic Knudsen pump, driving a flow of gas molecules towards the tip where the temperature is highest. The result is a circulating molecular flow within the chamber. Momentum exchange between the vibrating microspike and the flowing molecules causes an additional restoring force that can be measured as a tiny shift in the resonant frequency. The effect is strongest when the mean free path of the gas molecules is comparable with the dimensions of the vacuum chamber. The system offers a novel means of monitoring the behavior of weakly absorbing optomechanical sensors operating in vacuum.

Evolving a Behavioral Repertoire for a Walking Robot.

PubMed

Cully, A; Mouret, J-B

2016-01-01

Numerous algorithms have been proposed to allow legged robots to learn to walk. However, most of these algorithms are devised to learn walking in a straight line, which is not sufficient to accomplish any real-world mission. Here we introduce the Transferability-based Behavioral Repertoire Evolution algorithm (TBR-Evolution), a novel evolutionary algorithm that simultaneously discovers several hundreds of simple walking controllers, one for each possible direction. By taking advantage of solutions that are usually discarded by evolutionary processes, TBR-Evolution is substantially faster than independently evolving each controller. Our technique relies on two methods: (1) novelty search with local competition, which searches for both high-performing and diverse solutions, and (2) the transferability approach, which combines simulations and real tests to evolve controllers for a physical robot. We evaluate this new technique on a hexapod robot. Results show that with only a few dozen short experiments performed on the robot, the algorithm learns a repertoire of controllers that allows the robot to reach every point in its reachable space. Overall, TBR-Evolution introduced a new kind of learning algorithm that simultaneously optimizes all the achievable behaviors of a robot.

Origin of the high velocity gas in NGC 6231

NASA Astrophysics Data System (ADS)

Massa, Derck

2017-08-01

It is well known that clusters of massive stars are influenced by the presence of strong winds, that they are sources of diffuse X-rays from shocked gas, and that this gas can be vented into the surrounding region or the halo, forming a critical element in the process of galactic feedback. However, the details of how these different environments interact and evolve are far from complete. Recently, Massa (2017) showed that the peculiar C IV 1550 Ang absorption seen in several otherwise normal main sequence B stars in NGC 6231 is not intrinsic to the stars. Instead, this absorption, which extends to more than -2000 km/s, is due to intervening carbon rich, high speed gas in the cluster environment. In this proposal, we seek to identify the origin of the high speed gas. The proposed observations will enable us to determine whether it is due to the outer wind of the WC star WR79, or to a collective cluster wind, enriched by carbon from the wind of WR79. If it is due to the wind of WR79, then the new data will furnish a novel, less model dependent estimate of the mass loss rate of a WC star. If it is due to a collective wind from the cluster, then we could be witnessing an important stage of galactic feedback. In either case, the proposed observations will provide a unique and significant insight on how massive, open clusters evolve - insight that can only be obtained through UV spectroscopy.

SAM-Like Evolved Gas Analyses of Phyllosilicate Minerals and Applications to SAM Analyses of the Sheepbed Mudstone, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Franz, H. B.; Mahaffy, P. R.; Eigenbrode, J. L.; Stern, J. C.; Brunner, B.; Sutter, B.; Archer, P. D.; Ming , D. W.; Morris, R. V.;

Possible Detection of Perchlorates by Evolved Gas Analysis of Rocknest Soils: Global Implication

NASA Technical Reports Server (NTRS)

Archer, P. D., Jr.; Sutter, B.; Ming, D. W.; McKay, C. P.; Navarro-Gonzalez, R.; Franz, H. B.; McAdam, A.; Mahaffy, P. R.

2013-01-01

The Sample Analysis at Mars (SAM) instrument suite on board the Mars Science Laboratory (MSL) recently ran four samples from an aeolian bedform named Rocknest. Rocknest was selected as the source of the first samples analyzed because it is representative of both windblown material in Gale crater as well as the globally-distributed dust. The four samples analyzed by SAM were portioned from the fifth scoop at this location. The material delivered to SAM passed through a 150 m sieve and should have been well mixed during the sample acquisition/ preparation/handoff process. Rocknest samples were heated to 835 C at a 35 C/minute ramp rate with a He carrier gas flow rate of 1.5 standard cubic centimeters per minute and at an oven pressure of 30 mbar. Evolved gases were detected by a quadrupole mass spectrometer (QMS).

Origin of Chlorobenzene Detected by the Curiosity Rover in Yellowknife Bay: Evidence for Martian Organics in the Sheepbed Mudstone

NASA Technical Reports Server (NTRS)

Glavin, D.; Freissnet, C.; Eigenbrode, J.; Miller, K.; Martin, M.; Summons, R. E.; Steele, A.; Archer, D.; Brunner, A.; Buch, A.;

Impurity characterization of magnesium diuranate using simultaneous TG-DTA-FTIR measurements

NASA Astrophysics Data System (ADS)

Raje, Naina; Ghonge, Darshana K.; Hemantha Rao, G. V. S.; Reddy, A. V. R.

2013-05-01

Current studies describe the application of simultaneous thermogravimetry-differential thermal analysis - evolved gas analysis techniques for the compositional characterization of magnesium diuranate (MDU) with respect to the impurities present in the matrix. The stoichiometric composition of MDU was identified as MgU2O7ṡ3H2O. Presence of carbonate and sulphate as impurities in the matrix was confirmed through the evolved gas analysis using Fourier Transformation Infrared Spectrometry detection. Carbon and magnesium hydroxide content present as impurities in magnesium diuranate have been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Powder X-ray diffraction analysis of magnesium diuranate suggests the presence of magnesium hydroxide as impurity in the matrix. Also these studies confirm the formation of magnesium uranate, uranium sesquioxide and uranium dioxide above 1000 °C, due to the decomposition of magnesium diuranate.

Evolving Gravitationally Unstable Disks over Cosmic Time: Implications for Thick Disk Formation

NASA Astrophysics Data System (ADS)

Forbes, John; Krumholz, Mark; Burkert, Andreas

2012-07-01

Observations of disk galaxies at z ~ 2 have demonstrated that turbulence driven by gravitational instability can dominate the energetics of the disk. We present a one-dimensional simulation code, which we have made publicly available, that economically evolves these galaxies from z ~ 2 to z ~ 0 on a single CPU in a matter of minutes, tracking column density, metallicity, and velocity dispersions of gaseous and multiple stellar components. We include an H2-regulated star formation law and the effects of stellar heating by transient spiral structure. We use this code to demonstrate a possible explanation for the existence of a thin and thick disk stellar population and the age-velocity-dispersion correlation of stars in the solar neighborhood: the high velocity dispersion of gas in disks at z ~ 2 decreases along with the cosmological accretion rate, while at lower redshift the dynamically colder gas forms the low velocity dispersion stars of the thin disk.

Exploring the Structure and Evolution of the Universe: Multi-Band Profiles of the Known Gamma-Ray Pulsars

NASA Technical Reports Server (NTRS)

1998-01-01

As summarized in this pamphlet, some of the far-reaching underlying issues to be addressed include: What is the origin of the universe and its destiny; Why is the universe lumpy; How did the known structures of the universe evolve; How do galaxies evolve; How do massive black holes grow; How did the elemental composition of the universe evolve; What is the structure and behavior of matter in the extreme; and Is Einstein's general relativity theory right.

Method and apparatus for controlling gas evolution from chemical reactions

DOEpatents

Skorpik, J.R.; Dodson, M.G.

1999-05-25

The present invention is directed toward monitoring a thermally driven gas evolving chemical reaction with an acoustic apparatus. Signals from the acoustic apparatus are used to control a heater to prevent a run-away condition. A digestion module in combination with a robotic arm further automate physical handling of sample material reaction vessels. The invention is especially useful for carrying out sample procedures defined in EPA Methods SW-846. 8 figs.

Assessment of Aeromedical Evacuation Transport Patient Outcomes With and Without Cabin Altitude Restriction

DTIC Science & Technology

2017-08-24

reaction to stress (physical restraints) Other • Acute post-hemorrhagic anemia • Post-operative infection • Traumatic shock • Fat embolism ...decompression sickness/air gas embolism , and severe pulmonary disease [9]. The goal of this retrospective matched case-control study was to determine whether...patients who have cardiopulmonary concerns, free air in any closed cavity (e.g., skull, peritoneal cavity, injury, embolism ), or evolved gas (e.g

Organic Molecules in the Sheepbed Mudstone, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Miller, K. E.; Eigenbrode, J. L.; Summons, R. E.; Brunner, A. E.; Buch, A.; Szopa, C.; Archer, P. D.;

The Implications of a System-Wide Positive Behavioral Intervention Initiative: From Design to Successful Implementation

ERIC Educational Resources Information Center

Austin, Vance L.; Malow, Micheline S.; Josephs, Nikki L.; Ecker, Andrew J.

2016-01-01

Residential schools for students with emotional and behavioral disorders have been steadily evolving since the beginning of the 20th Century. Traditional behavioral approaches involving physical restraint and confinement have been replaced with more humanistic interventions involving positive reinforcement. This article traces this transformative…

Do motifs reflect evolved function?--No convergent evolution of genetic regulatory network subgraph topologies.

PubMed

Knabe, Johannes F; Nehaniv, Chrystopher L; Schilstra, Maria J

2008-01-01

Methods that analyse the topological structure of networks have recently become quite popular. Whether motifs (subgraph patterns that occur more often than in randomized networks) have specific functions as elementary computational circuits has been cause for debate. As the question is difficult to resolve with currently available biological data, we approach the issue using networks that abstractly model natural genetic regulatory networks (GRNs) which are evolved to show dynamical behaviors. Specifically one group of networks was evolved to be capable of exhibiting two different behaviors ("differentiation") in contrast to a group with a single target behavior. In both groups we find motif distribution differences within the groups to be larger than differences between them, indicating that evolutionary niches (target functions) do not necessarily mold network structure uniquely. These results show that variability operators can have a stronger influence on network topologies than selection pressures, especially when many topologies can create similar dynamics. Moreover, analysis of motif functional relevance by lesioning did not suggest that motifs were of greater importance to the functioning of the network than arbitrary subgraph patterns. Only when drastically restricting network size, so that one motif corresponds to a whole functionally evolved network, was preference for particular connection patterns found. This suggests that in non-restricted, bigger networks, entanglement with the rest of the network hinders topological subgraph analysis.

Thermal Properties of Lunar Regolith Simulants

NASA Technical Reports Server (NTRS)

Street, Kenneth W., Jr.; Ray, Chandra; Rickman, Doug; Scheiman, Daniel A.

2010-01-01

Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the Moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Thermo-Gravimetric Analysis (TGA) with Fourier Transform Infrared (FTIR) analysis provides information on evolved gas species and their evolution temperature profiles. The DTA and TGA studies included JSC-1A fine (Johnson Space Center Mare Type 1A simulant), NU-LHT-2M (National Aeronautics and Space Administration (NASA)-- United States Geological Survey (USGS)--Lunar Highlands Type 2M simulant) and its proposed feedstocks: anorthosite; dunite; high quality (HQ) glass and the norite from which HQ glass is produced. As an example, the DTA and TGA profiles for anorthosite follow. The DTA indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water is lost accounting for approximately 0.1 percent mass loss. Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals along with other volatile oxides. Limited TGA-FTIR data is available at the time of this writing. For JSC-1A fine, the TGA-FTIR indicates at least two kinds of water are evolved in the 100 to 500 and the 700 to 900 C ranges. Evolution of carbon dioxide types occurs in the 250 to 545, 545 to 705, and 705 to 985 C ranges. Geologically, the results are consistent with the evolution of "water" in its several forms, CO2 from break down of secondary carbonates and magmatic, dissolved gas and glass recrystallization

Recycling of electronic waste: Printed wiring boards

NASA Astrophysics Data System (ADS)

Luyima, Alex

Pyrolysis and leaching are the dominant techniques applied in the recycling of waste printed wiring boards (PWBs). Waste PWB pyrolysis is a highly polluting technology and produces brominated pyrolysis oils in addition to hydrogen bromide (HBr) gas. Moreover, leaching as a treatment process of waste PWBs is not well investigated. In this work, the pyrolysis of waste PWBs has been studied with the aim of reducing the amount of brominated oils and HBr gas evolved. The effects of powder inorganic chemicals (CaO, CaCO3, Fe 2O3, Al2O3, Y-Zeolite, and ZSM-5) additions on the pyrolysis of waste PWBs has been studied through experiments using a thermogravimetric-differential thermal analyzer connected to a mass spectrometer (TG-DTA-MS) and in a tube furnace at 900 °C. It has been shown that the kinetic models by Friedman, Flynn-Wall-Ozawa, and Kissinger are applicable to waste PWB pyrolysis at temperatures below 400 °C. Moreover, CaO, CaCO3, Fe2O3, Y-Zeolite, and ZSM-5 show a potential to reduce the amount of HBr gas evolved during pyrolysis in TG-DTA-MS. However, in the tube furnace pyrolysis experiments, CaO and CaCO3 were found to be the most effective chemical additions, with more than 90% reduction in total bromine (HBr and other brominated gases) evolved. It has also been demonstrated that the sequential leaching of waste PWBs with hydrochloric acid, nitric acid and aqua regia is capable of selective recovery of base and precious metals contained in waste PWBs.

Evolved stars as complex chemical laboratories - the quest for gaseous chemistry

NASA Astrophysics Data System (ADS)

Katrien Els Decin, Leen

2015-08-01

At the end of their life, most stars lose a large fraction of their mass through a stellar wind. The stellar winds of evolved (super)giant stars are the dominant suppliers for the pristine building blocks of the interstellar medium (ISM). Crucial to the understanding of the chemical life cycle of the ISM is hence a profound insight in the chemical and physical structure governing these stellar winds.These winds are really unique chemical laboratories in which currently more than 70 different molecules and 15 different dust species are detected. Several chemical processes such as neutral-neutral and ion-molecule gas-phase reactions, dust nucleation and growth, and photo-processes determine the chemical content of these winds. However, gas-phase and dust-nucleation chemistry for astronomical environments still faces many challenges. One should realize that only ˜15% of the rate coefficients for gas-phase reactions considered to occur in (inter/circum)stellar regions at temperatures (T) below 300K have been subject to direct laboratory determinations and that the temperature dependence of the rate constants is often not known; only ˜2% have rate constants at T<200K and less than 0.5% at T<100 K. For stellar wind models, an important bottleneck occurs among the reactions involving silicon- and sulfur-bearing species, for which only a few have documented reaction rates. Often, researchers are implementing ‘educated guesses’ for these unknown rates, sometimes forcing the network to yield predictions concurring with (astronomical) observations. Large uncertainties are inherent in this type of ‘optimized’ chemical schemes.Thanks to an ERC-CoG grant, we are now in the position to solve some riddles involved in understanding the gas-phase chemistry in evolved stars. In this presentation, I will demonstrate the need for accurate temperature-dependent gas-phase reaction rate constants and will present our new laboratory equipment built to measure the rate constants for species key in stellar wind chemistry. Specifically, we aim to obtain the rate constants of reactions involving silicon- and sulphur bearing species and HCCO for 30

Nanophase Carbonates on Mars: Does Evolved Gas Analysis of Nanophase Carbonates Reveal a Large Organic Carbon Budget in Near-surface Martian Materials?

NASA Astrophysics Data System (ADS)

Archer, P. D., Jr.; Ming, D. W.; Sutter, B.; Niles, P. B.; Eigenbrode, J. L.

2015-12-01

Evolved Gas Analysis (EGA), which involves heating a sample and monitoring the gases released, has been performed on Mars by the Viking gas chromatography/mass spectrometry instruments, the Thermal and Evolved Gas Analyzer (TEGA) on the Phoenix lander, and the Sample Analysis at Mars (SAM) instrument on the Mars Science Laboratory. All of these instruments detected CO2 released during sample analysis at abundances of ~0.1 to 5 wt% assuming a carbonate source. The source of the CO2 can be constrained by evaluating the temperature of the gas release, a capability of both the TEGA and SAM instruments. The samples analyzed by SAM show that the majority of the CO2is released below 400 °C, much lower than traditional carbonate decomposition temperatures which can be as low as 400 °C for some siderites, with magnesites and calcites decomposing at even higher temperatures. In addition to mineralogy, decomposition temperature can depend on particle size (among other factors). If carbonates formed on Mars under low temperature and relative humidity conditions, the resulting small particle size (nanophase) carbonates could have low decomposition temperatures. We have found that calcite can be synthesized by exposing CaO to water vapor and CO2 and that the resulting mineral has an EGA peak of ~550 °C for CO2, which is about 200 °C lower than for other calcites. Work is ongoing to produce Fe and Mg-bearing carbonates using the same process. Current results suggest that nanophase calcium carbonates cannot explain the CO2 released from martian samples. If the decomposition temperatures of Mg and Fe-bearing nanophase carbonates are not significantly lower than 400 °C, other candidate sources include oxalates and carboxylated organic molecules. If present, the abundance of organic carbon in these samples could be > 0.1 wt % (1000s of ppm), a signficant departure from the paradigm of the organic-poor Mars based on Viking results.

Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

DOE PAGES

Patel, Mogon; Bowditch, Martin; Jones, Ben; ...

2012-12-08

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. In these studies, a Scout-EN TM heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time during storage at 75°C under vacuum conditions (< 1mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cmmore » -1, respectively. We present a comparison of three highly filled poly (ethyleneco- vinyl acetate) resins.« less

The Transition from Animal to Linguistic Communication.

PubMed

Smit, Harry

Darwin's theory predicts that linguistic behavior gradually evolved out of animal forms of communication (signaling). However, this prediction is confronted by the conceptual problem that there is an essential difference between signaling and linguistic behavior: using words is a normative practice. It is argued that we can resolve this problem if we (1) note that language evolution is the outcome of an evolutionary transition, and (2) observe that the use of words evolves during ontogenesis out of babbling. It is discussed that language evolved as the result of an expansion of the vocalizing powers of our ancestors. This involved an increase in the volitional control of our speech apparatus (leading to the ability to produce new combinations of vowels and consonants), but also the evolution of socially guided learning. It resulted in unique human abilities, namely doing things with words and later reasoning and giving reasons.

The evolution of conformist transmission in social learning when the environment changes periodically.

PubMed

Nakahashi, Wataru

2007-08-01

Conformity is often observed in human social learning. Social learners preferentially imitate the majority or most common behavior in many situations, though the strength of conformity varies with the situation. Why has such a psychological tendency evolved? I investigate this problem by extending a standard model of social learning evolution with infinite environmental states (Feldman, M.W., Aoki, K., Kumm, J., 1996. Individual versus social learning: evolutionary analysis in a fluctuating environment. Anthropol. Sci. 104, 209-231) to include conformity bias. I mainly focus on the relationship between the strength of conformity bias that evolves and environmental stability, which is one of the most important factors in the evolution of social learning. Using the evolutionarily stable strategy (ESS) approach, I show that conformity always evolves when environmental stability and the cost of adopting a wrong behavior are small, though environmental stability and the cost of individual learning both negatively affect the strength of conformity.

Translating basic behavioral and social science research to clinical application: the EVOLVE mixed methods approach.

PubMed

Peterson, Janey C; Czajkowski, Susan; Charlson, Mary E; Link, Alissa R; Wells, Martin T; Isen, Alice M; Mancuso, Carol A; Allegrante, John P; Boutin-Foster, Carla; Ogedegbe, Gbenga; Jobe, Jared B

2013-04-01

To describe a mixed-methods approach to develop and test a basic behavioral science-informed intervention to motivate behavior change in 3 high-risk clinical populations. Our theoretically derived intervention comprised a combination of positive affect and self-affirmation (PA/SA), which we applied to 3 clinical chronic disease populations. We employed a sequential mixed methods model (EVOLVE) to design and test the PA/SA intervention in order to increase physical activity in people with coronary artery disease (post-percutaneous coronary intervention [PCI]) or asthma (ASM) and to improve medication adherence in African Americans with hypertension (HTN). In an initial qualitative phase, we explored participant values and beliefs. We next pilot tested and refined the intervention and then conducted 3 randomized controlled trials with parallel study design. Participants were randomized to combined PA/SA versus an informational control and were followed bimonthly for 12 months, assessing for health behaviors and interval medical events. Over 4.5 years, we enrolled 1,056 participants. Changes were sequentially made to the intervention during the qualitative and pilot phases. The 3 randomized controlled trials enrolled 242 participants who had undergone PCI, 258 with ASM, and 256 with HTN (n = 756). Overall, 45.1% of PA/SA participants versus 33.6% of informational control participants achieved successful behavior change (p = .001). In multivariate analysis, PA/SA intervention remained a significant predictor of achieving behavior change (p < .002, odds ratio = 1.66), 95% CI [1.22, 2.27], controlling for baseline negative affect, comorbidity, gender, race/ethnicity, medical events, smoking, and age. The EVOLVE method is a means by which basic behavioral science research can be translated into efficacious interventions for chronic disease populations.

Translating Basic Behavioral and Social Science Research to Clinical Application: The EVOLVE Mixed Methods Approach

PubMed Central

Peterson, Janey C.; Czajkowski, Susan; Charlson, Mary E.; Link, Alissa R.; Wells, Martin T.; Isen, Alice M.; Mancuso, Carol A.; Allegrante, John P.; Boutin-Foster, Carla; Ogedegbe, Gbenga; Jobe, Jared B.

2012-01-01

Objective To describe a mixed-methods approach to develop and test a basic behavioral science-informed intervention to motivate behavior change in three high-risk clinical populations. Our theoretically-derived intervention comprised a combination of positive affect and self-affirmation (PA/SA) which we applied to three clinical chronic disease populations. Methods We employed a sequential mixed methods model (EVOLVE) to design and test the PA/SA intervention in order to increase physical activity in people with coronary artery disease (post-percutaneous coronary intervention [PCI]) or asthma (ASM), and to improve medication adherence in African Americans with hypertension (HTN). In an initial qualitative phase, we explored participant values and beliefs. We next pilot tested and refined the intervention, and then conducted three randomized controlled trials (RCTs) with parallel study design. Participants were randomized to combined PA/SA vs. an informational control (IC) and followed bimonthly for 12 months, assessing for health behaviors and interval medical events. Results Over 4.5 years, we enrolled 1,056 participants. Changes were sequentially made to the intervention during the qualitative and pilot phases. The three RCTs enrolled 242 PCI, 258 ASM and 256 HTN participants (n=756). Overall, 45.1% of PA/SA participants versus 33.6% of IC participants achieved successful behavior change (p=0.001). In multivariate analysis PA/SA intervention remained a significant predictor of achieving behavior change (p<0.002, OR=1.66, 95% CI 1.22–2.27), controlling for baseline negative affect, comorbidity, gender, race/ethnicity, medical events, smoking and age. Conclusions The EVOLVE method is a means by which basic behavioral science research can be translated into efficacious interventions for chronic disease populations. PMID:22963594

Emergence of Swarming Behavior: Foraging Agents Evolve Collective Motion Based on Signaling.

PubMed

Witkowski, Olaf; Ikegami, Takashi

2016-01-01

Swarming behavior is common in biology, from cell colonies to insect swarms and bird flocks. However, the conditions leading to the emergence of such behavior are still subject to research. Since Reynolds' boids, many artificial models have reproduced swarming behavior, focusing on details ranging from obstacle avoidance to the introduction of fixed leaders. This paper presents a model of evolved artificial agents, able to develop swarming using only their ability to listen to each other's signals. The model simulates a population of agents looking for a vital resource they cannot directly detect, in a 3D environment. Instead of a centralized algorithm, each agent is controlled by an artificial neural network, whose weights are encoded in a genotype and adapted by an original asynchronous genetic algorithm. The results demonstrate that agents progressively evolve the ability to use the information exchanged between each other via signaling to establish temporary leader-follower relations. These relations allow agents to form swarming patterns, emerging as a transient behavior that improves the agents' ability to forage for the resource. Once they have acquired the ability to swarm, the individuals are able to outperform the non-swarmers at finding the resource. The population hence reaches a neutral evolutionary space which leads to a genetic drift of the genotypes. This reductionist approach to signal-based swarming not only contributes to shed light on the minimal conditions for the evolution of a swarming behavior, but also more generally it exemplifies the effect communication can have on optimal search patterns in collective groups of individuals.

Thermal and Chemical Characterization of Non-metallic Materials Using Coupled Thermogravimetric Analysis and Infrared Spectroscopy

NASA Technical Reports Server (NTRS)

Huff, Timothy L.; Griffin, Dennis E. (Technical Monitor)

2001-01-01

Thermogravimetric analysis (TGA) is widely employed in the thermal characterization of non-metallic materials, yielding valuable information on decomposition characteristics of a sample over a wide temperature range. However, a potential wealth of chemical information is lost during the process, with the evolving gases generated during thermal decomposition escaping through the exhaust line. Fourier Transform-Infrared spectroscopy (FT-IR) is a powerful analytical technique for determining many chemical constituents while in any material state, in this application, the gas phase. By linking these two techniques, evolving gases generated during the TGA process are directed into an appropriately equipped infrared spectrometer for chemical speciation. Consequently, both thermal decomposition and chemical characterization of a material may be obtained in a single sample run. In practice, a heated transfer line is employed to connect the two instruments while a purge gas stream directs the evolving gases into the FT-IR, The purge gas can be either high purity air or an inert gas such as nitrogen to allow oxidative and pyrolytic processes to be examined, respectively. The FT-IR data is collected real-time, allowing continuous monitoring of chemical compositional changes over the course of thermal decomposition. Using this coupled technique, an array of diverse materials has been examined, including composites, plastics, rubber, fiberglass epoxy resins, polycarbonates, silicones, lubricants and fluorocarbon materials. The benefit of combining these two methodologies is of particular importance in the aerospace community, where newly developing materials have little available data with which to refer. By providing both thermal and chemical data simultaneously, a more definitive and comprehensive characterization of the material is possible. Additionally, this procedure has been found to be a viable screening technique for certain materials, with the generated data useful in the selection of other appropriate analytical procedures for further material characterization.

Preparation of water samples for carbon-14 dating

USGS Publications Warehouse

Feltz, H.R.; Hanshaw, Bruce B.

1963-01-01

For most natural water, a large sample is required to provide the 3 grams of carbon needed for a carbon-14 determination. A field procedure for isolating total dissolved-carbonate species is described. Carbon dioxide gas is evolved by adding sulfuric acid to the water sample; the gas is then collected in a sodium hydroxide trap by recycling in a closed system. The trap is then transported to the dating laboratory where the carbon-14 is counted.

Influence of ionization on ultrafast gas-based nonlinear fiber optics.

PubMed

Chang, W; Nazarkin, A; Travers, J C; Nold, J; Hölzer, P; Joly, N Y; Russell, P St J

2011-10-10

We numerically investigate the effect of ionization on ultrashort high-energy pulses propagating in gas-filled kagomé-lattice hollow-core photonic crystal fibers by solving an established uni-directional field equation. We consider the dynamics of two distinct regimes: ionization induced blue-shift and resonant dispersive wave emission in the deep-UV. We illustrate how the system evolves between these regimes and the changing influence of ionization. Finally, we consider the effect of higher ionization stages.

The Relationship between Screen Time and Sexual Behaviors among Middle School Students

ERIC Educational Resources Information Center

Barr, Elissa M.; Moore, Michele J.; Johnson, Tammie; Merten, Julie; Stewart, William P.

2014-01-01

Reducing risky sexual behaviors and their negative health outcomes in youth remains a priority for health educators. Years of research have documented media's effect on various adolescent health risks, including sexual behaviors. As technology evolves and youth access to media increases, understanding the role of media in adolescent health risk…

News Media Industry

DTIC Science & Technology

2007-01-01

convergence of media types, rapidly evolving technology, changing consumer behavior , and traditionalists ensconced in the ways of the past all...changing consumer behavior have all contributed to uncertain times for these media icons. Newspaper readership and subscriptions levels continue to...consistently center on changing technologies, corporate pressures, changing consumer behavior and revenue generation (advertising). Because it’s

The coevolution of parochial altruism and war.

PubMed

Choi, Jung-Kyoo; Bowles, Samuel

2007-10-26

Altruism-benefiting fellow group members at a cost to oneself-and parochialism-hostility toward individuals not of one's own ethnic, racial, or other group-are common human behaviors. The intersection of the two-which we term "parochial altruism"-is puzzling from an evolutionary perspective because altruistic or parochial behavior reduces one's payoffs by comparison to what one would gain by eschewing these behaviors. But parochial altruism could have evolved if parochialism promoted intergroup hostilities and the combination of altruism and parochialism contributed to success in these conflicts. Our game-theoretic analysis and agent-based simulations show that under conditions likely to have been experienced by late Pleistocene and early Holocene humans, neither parochialism nor altruism would have been viable singly, but by promoting group conflict, they could have evolved jointly.

MNA of Chlorinated Solvents and Fuel Oxygenates: Why it occurs, how it evolved, and using stable carbon isotopes to predict plume behavior

EPA Science Inventory

The organisms that degrade MTBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

Fueling nuclear activity in disk galaxies: Starbursts and monsters

NASA Astrophysics Data System (ADS)

Heller, Clayton H.; Shlosman, Isaac

1994-03-01

We study the evolution of the gas distribution in a globally unstable galactic disk with a particular emphasis on the gasdynamics in the central kiloparsec and the fueling activity there. The two-component self-gravitating disk is embedded in a responsive halo of comparable mass. The gas and stars are evolved using a three-dimensional hybrid smoothed particle hydrodynamics/N-body code and the gravitational interactions are calculated using a hierarchical TREE algorithm. A massive 'star formation' is introduced when the gas becomes Jeans unstable and locally exceeds the critical density of approximately 100 solar mass pc-3. The newly formed OB stars deposit energy in the gas by means of radiation-driven winds and supernovae. This energy is partially thermalized (efficiency of a few percent); the rest is radiated away. Models without star formation are evolved for a comparison. The effect of a massive object at the disk center is studied by placing a 'seed' black hole (BH) of 5 x 107 solar mass with an accretion radius of 20 pc. The tendency of the system to form a massive object 'spontaneously' is tested in models without the BH. We find that for models without star formation the bar- or dynamical friction-driven inflows lead to (1) domination of the central kpc by a few massive clouds that evolve into a single object probably via a cloud binary system, with and without a 'seed' BH, (2) accretion onto the BH which has a sporadic character, and (3) formation of remnant disks around the BH with a radius of 60-80 pc which result from the capture and digestion of clouds. For models with star formation, we find that (1) the enrgy input into the gas induces angular momentum loss and inflow rates by a factor less than 3, (2) the star formation is concentrated mainly at the apocenters of the gaseous circulation in the stellar bar and in the nuclear region, (3) the nuclear starburst phase appears to be very luminous approximately 1045-1046 erg/s and episodic with a typical single burst duration of aproximately 107 yr, and (4) the starburst phase coincides with both the gas becoming dynamically important and the catastrophic growth of the BH. It ends with the formation of cold residual less than 1 kpc radius gas disks. Models without the 'seed' BH form less than 1 kpc radius fat disks which dominate the dynamics. Gaseous bars follow, drive further inflow, and may fission into a massive cloud binary system at the center.

Transonic aerodynamics of dense gases. M.S. Thesis - Virginia Polytechnic Inst. and State Univ., Apr. 1990

NASA Technical Reports Server (NTRS)

Morren, Sybil Huang

1991-01-01

Transonic flow of dense gases for two-dimensional, steady-state, flow over a NACA 0012 airfoil was predicted analytically. The computer code used to model the dense gas behavior was a modified version of Jameson's FL052 airfoil code. The modifications to the code enabled modeling the dense gas behavior near the saturated vapor curve and critical pressure region where the fundamental derivative, Gamma, is negative. This negative Gamma region is of interest because the nonclassical gas behavior such as formation and propagation of expansion shocks, and the disintegration of inadmissible compression shocks may exist. The results indicated that dense gases with undisturbed thermodynamic states in the negative Gamma region show a significant reduction in the extent of the transonic regime as compared to that predicted by the perfect gas theory. The results support existing theories and predictions of the nonclassical, dense gas behavior from previous investigations.

TGS pipeline primed for Argentine growth, CEO says

DOE Office of Scientific and Technical Information (OSTI.GOV)

Share, J.

Nowhere in Latin America has the privatization process been more aggressively pursued than in Argentina where President Carlos Menem has successfully turned over the bulk of state companies to the private sector. In the energy sector, that meant the divestiture in 1992 of Gas del Estado, the state-owned integrated gas transportation and distribution company. It was split in two transportation companies: Transportadora de Gas del Sur (TGS) and Transportadora de Gas del Norte (TGN), and eight distribution companies. TGS is the largest transporter of natural gas in Argentina, delivering more than 60 percent of that nation`s total gas consumption withmore » a capacity of 1.9 Bcf/d. This is the second in a series of Pipeline and Gas Journal special reports that discuss the evolving strategies of the natural gas industry as it continues to restructure amid deregulation. The article focuses on TGS, the Argentine pipeline system in which Enron Corp. is a key participant.« less

Behavioral and neural effects of intra-striatal infusion of anti-streptococcal antibodies in rats

PubMed Central

Lotan, Dafna; Benhar, Itai; Alvarez, Kathy; Mascaro-Blanco, Adita; Brimberg, Lior; Frenkel, Dan; Cunningham, Madeleine W.; Joel, Daphna

2014-01-01

Group A β-hemolytic streptococcal (GAS) infection is associated with a spectrum of neuropsychiatric disorders. The leading hypothesis regarding this association proposes that a GAS infection induces the production of auto-antibodies, which cross-react with neuronal determinants in the brain through the process of molecular mimicry. We have recently shown that exposure of rats to GAS antigen leads to the production of anti-neuronal antibodies concomitant with the development of behavioral alterations. The present study tested the causal role of the antibodies by assessing the behavior of naïve rats following passive transfer of purified antibodies from GAS-exposed rats. Immunoglobulin G (IgG) purified from the sera of GAS-exposed rats was infused directly into the striatum of naïve rats over a 21-day period. Their behavior in the induced-grooming, marble burying, food manipulation and beam walking assays was compared to that of naïve rats infused with IgG purified from adjuvant-exposed rats as well as of naïve rats. The pattern of in vivo antibody deposition in rat brain was evaluated using immunofluorescence and colocalization. Infusion of IgG from GAS-exposed rats to naïve rats led to behavioral and motor alterations partially mimicking those seen in GAS-exposed rats. IgG from GAS-exposed rats reacted with D1 and D2 dopamine receptors and 5HT-2A and 5HT-2C serotonin receptors in vitro. In vivo, IgG deposits in the striatum of infused rats colocalized with specific brain proteins such as dopamine receptors, the serotonin transporter and other neuronal proteins. Our results demonstrate the potential pathogenic role of autoantibodies produced following exposure to GAS in the induction of behavioral and motor alterations, and support a causal role for autoantibodies in GAS-related neuropsychiatric disorders. PMID:24561489

Bio-conversion of water hyacinths into methane gas, part 1

NASA Technical Reports Server (NTRS)

Wolverton, B. C.; Mcdonald, R. C.; Gordon, J.

1974-01-01

Bio-gas and methane production from the microbial anaerobic decomposition of water hyacinths (Eichhornia crassipes) (Mart) Solms was investigated. These experiments demonstrated the ability of water hyacinths to produce an average of 13.9 ml of methane gas per gram of wet plant weight. This study revealed that sample preparation had no significant effect on bio-gas and/or methane production. Pollution of water hyacinths by two toxic heavy materials, nickel and cadmium, increased the rate of methane production from 51.8 ml/day for non-contaminated plants incubated at 36 C to 81.0 ml/day for Ni-Cd contaminated plants incubated at the same temperature. The methane content of bio-gas evolved from the anaerobic decomposition of Ni-Cd contaminated plants was 91.1 percent as compared to 69.2 percent methane content of bio-gas collected from the fermentation of non-contaminated plants.

Carbon and Sulfur Isotopic Composition of Yellowknife Bay Sediments: Measurements by the Sample Analysis at Mars (SAM) Quadrupole Mass Spectrometer

NASA Technical Reports Server (NTRS)

Franz, H. B.; Mahaffy, P. R.; Stern, J. C.; Eigenbrode, J. L.; Steele, A.; Ming, D. W.; McAdam, A. C.; Freissinet, C.; Glavin, D. P.; Archer, P. D.;

Evidence of refractory organic matter preserved in the mudstones of Yellowknife Bay and the Murray Formations

NASA Astrophysics Data System (ADS)

Eigenbrode, J. L.; Steele, A.; Summons, R. E.; Sutter, B.; McAdam, A.; Franz, H. B.; Mahaffy, P. R.; Conrad, P. G.; Freissinet, C.; Glavin, D. P.; Millan, M.; Ming, D. W.

2015-12-01

Volatiles from high-temperature (above 500°C) pyrolysis of drilled and sieved deltaic/lacustrine mudstones at Yellowknife Bay and Pahrump Hills were detected by the Sample Analysis at Mars (SAM) instrument's evolved gas analysis experiment onboard the Curiosity rover in Gale Crater, Mars. Mass fragments detected from the mudstones are consistent with C1-C4 alkyl and single-ring aromatic components that evolve at different temperatures and often in multiple phases. Concurrent release of oxidized sulfur (sulfur dioxide and sulfur trioxide), sulfide gases (hydrogen sulfide, carbonyl sulfide, carbon disulfide, dimethylsulfide or thiol, and thiophene) suggest that either these gases are evolving directly from the mudstone or are products of gas phase reactions in the SAM oven, or both. Multiple chlorohydrocarbon releases are also observed in analysis of the Mojave mudstone indicating punctuated organic releases from the sample. The organic signatures observed are unique to specific samples and are not observed in blanks or all samples, nor can the SAM background explain them. These results suggest that geologically refractory organic matter has been preserved in some Hesperian mudstones despite possible acid-sulfate weathering (as suggested by jarosite in Mojave) and exposure to ionizing cosmic rays after exhumation. We will report on ongoing study of these samples.

Photochemical Aging of α-pinene and β-pinene Secondary Organic Aerosol formed from Nitrate Radical Oxidation: New Insights into the Formation and Fates of Highly Oxygenated Gas- and Particle-phase Organic Nitrates

NASA Astrophysics Data System (ADS)

Nah, T.; Sanchez, J.; Boyd, C.; Ng, N. L.

2015-12-01

The nitrate radical (NO3), one of the most important oxidants in the nocturnal atmosphere, can react rapidly with a variety of biogenic volatile organic compounds (BVOCs) to form high mass concentrations of secondary organic aerosol (SOA) and organic nitrates (ON). Despite its critical importance in aerosol formation, the mechanisms and products from the NO3 oxidation of BVOCs have been largely unexplored, and the fates of their SOA and ON after formation are not well characterized. In this work, we studied the formation of SOA and ON from the NO3 oxidation of α-pinene and β-pinene and investigated for the first time how they evolve during dark and photochemical aging through a series of chamber experiments performed at the Georgia Tech Environmental Chamber (GTEC) facility. The α-pinene and β-pinene SOA are characterized using real-time gas- and particle-phase measurements, which are used to propose mechanisms for SOA and organic nitrate formation and aging. Highly oxygenated gas- and particle-phase ON (containing as many as 9 oxygen atoms) are detected during the NO3 reaction. In addition, the β-pinene SOA and α-pinene SOA exhibited drastically different behavior during photochemical aging. Our results indicate that nighttime ON formed by NO3+monoterpene chemistry can serve as either NOx reservoirs or sinks depending on the monoterpene precursor. Results from this study provide fundamental data for evaluating the contributions of NO3+monoterpene reactions to ambient OA measured in the Southeastern U.S.

Molecular genetic anatomy of inter- and intraserotype variation in the human bacterial pathogen group A Streptococcus.

PubMed

Beres, Stephen B; Richter, Ellen W; Nagiec, Michal J; Sumby, Paul; Porcella, Stephen F; DeLeo, Frank R; Musser, James M

2006-05-02

In recent years we have studied the relationship between strain genotypes and patient phenotypes in group A Streptococcus (GAS), a model human bacterial pathogen that causes extensive morbidity and mortality worldwide. We have concentrated our efforts on serotype M3 organisms because these strains are common causes of pharyngeal and invasive infections, produce unusually severe invasive infections, and can exhibit epidemic behavior. Our studies have been hindered by the lack of genome-scale phylogenies of multiple GAS strains and whole-genome sequences of multiple serotype M3 strains recovered from individuals with defined clinical phenotypes. To remove some of these impediments, we sequenced to closure the genome of four additional GAS strains and conducted comparative genomic resequencing of 12 contemporary serotype M3 strains representing distinct genotypes and phenotypes. Serotype M3 strains are a single phylogenetic lineage. Strains from asymptomatic throat carriers were significantly less virulent for mice than sterile-site isolates and evolved to a less virulent phenotype by multiple genetic pathways. Strain persistence or extinction between epidemics was strongly associated with presence or absence, respectively, of the prophage encoding streptococcal pyrogenic exotoxin A. A serotype M3 clone significantly underrepresented among necrotizing fasciitis cases has a unique frameshift mutation that truncates MtsR, a transcriptional regulator controlling expression of genes encoding iron-acquisition proteins. Expression microarray analysis of this clone confirmed significant alteration in expression of genes encoding iron metabolism proteins. Our analysis provided unprecedented detail about the molecular anatomy of bacterial strain genotype-patient phenotype relationships.

Sex in Millipedes: Laboratory Studies on Sexual Selection.

ERIC Educational Resources Information Center

Telford, S. R.; Dangerfield, J. M.

1990-01-01

Activities that consider the courtship behavior and mating patterns of millipedes are presented. The functional significance of a behavior that has evolved through indirect competition between males is discussed. The procedures for seven experiments, results, and interpretations are included. (KR)

ULTRAVIOLET PROTECTIVE COMPOUNDS AS A RESPONSE TO ULTRAVIOLET RADIATION EXPOSURE

EPA Science Inventory

Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet radiation. In response to UVR organisms have adapted myriad responses; behavioral, morphological and physiological. Behaviorally, some orga...

Electrical resistance behavior of oxyfluorinated graphene under oxidizing and reducing gas exposure.

PubMed

Im, Ji Sun; Bae, Tae-Sung; Shin, Eunjeong; Lee, Young-Seak

2014-03-01

The electrical resistance behavior of graphene was studied under oxidizing and reducing gas exposure. The graphene surface was modified via oxyfluorination to obtain a specific surface area and oxygen functional groups. Fluorine radicals provided improved pore structure and introduction of an oxygen functional group. A high-performance gas sensor was obtained based on enlarged target gas adsorption sites and an enhanced electron charge transfer between the target gas and carbon surface via improved pore structure and the introduction of oxygen functional groups, respectively.

Chronology and pyroclastic stratigraphy of the May 18, 1980, eruption of Mount St. Helens, Washington

NASA Technical Reports Server (NTRS)

Criswell, C. William

1987-01-01

The eruption of Mount St. Helens on May 18, 1980 can be subdivided into six phases: the paroxysmal phase I, the early Plinian phase II, the early ash flow phase III, the climactic phase IV, the late ash flow phase V, and phase VI, the activity of which consisted of a low-energy ash plume. These phases are correlated with stratigraphic subunits of ash-fall tephra and pyroclastic flow deposits. Sustained vertical discharge of phase II produced evolved dacite with high S/Cl ratios. Ash flow activity of phase III is attributed to decreases in gas content, indicated by reduced S/Cl ratios and increased clast density of the less evolved gray pumice. Climactic events are attributed to vent clearing and exhaustion of the evolved dacite.

The comparative effect of FUV, EUV and X-ray disc photoevaporation on gas giant separations

NASA Astrophysics Data System (ADS)

Jennings, Jeff; Ercolano, Barbara; Rosotti, Giovanni P.

2018-04-01

Gas giants' early (≲ 5 Myr) orbital evolution occurs in a disc losing mass in part to photoevaporation driven by high energy irradiance from the host star. This process may ultimately overcome viscous accretion to disperse the disc and halt migrating giants by starving their orbits of gas, imprinting on giant planet separations in evolved systems. Inversion of this distribution could then give insight into whether stellar FUV, EUV or X-ray flux dominates photoevaporation, constraining planet formation and disc evolution models. We use a 1D hydrodynamic code in population syntheses for gas giants undergoing Type II migration in a viscously evolving disc subject to either a primarily FUV, EUV or X-ray flux from a pre-solar T Tauri star. The photoevaporative mass loss profile's unique peak location and width in each energetic regime produces characteristic features in the distribution of giant separations: a severe dearth of ≲ 2 MJ planets interior to 5 AU in the FUV scenario, a sharp concentration of ≲ 3 MJ planets between ≈1.5 - 2 AU in the EUV case, and a relative abundance of ≈2 - 3.5 MJ giants interior to 0.5 AU in the X-ray model. These features do not resemble the observational sample of gas giants with mass constraints, though our results do show some weaker qualitative similarities. We thus assess how the differing photoevaporative profiles interact with migrating giants and address the effects of large model uncertainties as a step to better connect disc models with trends in the exoplanet population.

The comparative effect of FUV, EUV and X-ray disc photoevaporation on gas giant separations

NASA Astrophysics Data System (ADS)

Jennings, Jeff; Ercolano, Barbara; Rosotti, Giovanni P.

2018-07-01

Gas giants' early (≲5 Myr) orbital evolution occurs in a disc losing mass in part to photoevaporation driven by high energy irradiance from the host star. This process may ultimately overcome viscous accretion to disperse the disc and halt migrating giants by starving their orbits of gas, imprinting on giant planet separations in evolved systems. Inversion of this distribution could then give insight into whether the stellar FUV, EUV or X-ray flux dominates photoevaporation, constraining planet formation and disc evolution models. We use a 1D hydrodynamic code in population syntheses for gas giants undergoing Type II migration in a viscously evolving disc subject to either a primarily FUV, EUV or X-ray flux from a pre-solar T Tauri star. The photoevaporative mass loss profile's unique peak location and width in each energetic regime produces characteristic features in the distribution of giant separations: a severe dearth of ≲2 MJ planets interior to 5 au in the FUV scenario, a sharp concentration of ≲3 MJ planets between ≈1.5-2 au in the EUV case and a relative abundance of ≈2-3.5 MJ giants interior to 0.5 au in the X-ray model. These features do not resemble the observational sample of gas giants with mass constraints, although our results do show some weaker qualitative similarities. We thus assess how the differing photoevaporative profiles interact with migrating giants and address the effects of large model uncertainties as a step to better connect disc models with trends in the exoplanet population.

Electrodeposition of Ni-Mo alloy coatings for water splitting reaction

NASA Astrophysics Data System (ADS)

Shetty, Akshatha R.; Hegde, Ampar Chitharanjan

2018-04-01

The present study reports the development of Ni-Mo alloy coatings for water splitting applications, using a citrate bath the inducing effect of Mo (reluctant metal) on electrodeposition, its relationship with their electrocatalytic efficiency were studied. The alkaline water splitting efficiency of Ni-Mo alloy coatings, for both hydrogen evolution reaction (HER) and oxygen evolution reaction were tested using cyclic voltammetry (CV) and chronopotentiometry (CP) techniques. Moreover, the practical utility of these electrode materials were evaluated by measuring the amount of H2 and O2 gas evolved. The variation in electrocatalytic activity with composition, structure, and morphology of the coatings were examined using XRD, SEM, and EDS analyses. The experimental results showed that Ni-Mo alloy coating is the best electrode material for alkaline HER and OER reactions, at lower and higher deposition current densities (c. d.'s) respectively. This behavior is attributed by decreased Mo and increased Ni content of the alloy coating and the number of electroactive centers.

Risk sensitivity as an evolutionary adaptation

NASA Astrophysics Data System (ADS)

Hintze, Arend; Olson, Randal S.; Adami, Christoph; Hertwig, Ralph

2015-02-01

Risk aversion is a common behavior universal to humans and animals alike. Economists have traditionally defined risk preferences by the curvature of the utility function. Psychologists and behavioral economists also make use of concepts such as loss aversion and probability weighting to model risk aversion. Neurophysiological evidence suggests that loss aversion has its origins in relatively ancient neural circuitries (e.g., ventral striatum). Could there thus be an evolutionary origin to risk aversion? We study this question by evolving strategies that adapt to play the equivalent mean payoff gamble. We hypothesize that risk aversion in this gamble is beneficial as an adaptation to living in small groups, and find that a preference for risk averse strategies only evolves in small populations of less than 1,000 individuals, or in populations segmented into groups of 150 individuals or fewer - numbers thought to be comparable to what humans encountered in the past. We observe that risk aversion only evolves when the gamble is a rare event that has a large impact on the individual's fitness. As such, we suggest that rare, high-risk, high-payoff events such as mating and mate competition could have driven the evolution of risk averse behavior in humans living in small groups.

Cooperative behavior and phase transitions in co-evolving stag hunt game

NASA Astrophysics Data System (ADS)

Zhang, W.; Li, Y. S.; Xu, C.; Hui, P. M.

2016-02-01

Cooperative behavior and different phases in a co-evolving network dynamics based on the stag hunt game is studied. The dynamical processes are parameterized by a payoff r that tends to promote non-cooperative behavior and a probability q for a rewiring attempt that could isolate the non-cooperators. The interplay between the parameters leads to different phases. Detailed simulations and a mean field theory are employed to reveal the properties of different phases. For small r, the cooperators are the majority and form a connected cluster while the non-cooperators increase with q but remain isolated over the whole range of q, and it is a static phase. For sufficiently large r, cooperators disappear in an intermediate range qL ≤ q ≤qU and a dynamical all-non-cooperators phase results. For q >qU, a static phase results again. A mean field theory based on how the link densities change in time by the co-evolving dynamics is constructed. The theory gives a phase diagram in the q- r parameter space that is qualitatively in agreement with simulation results. The sources of discrepancies between theory and simulations are discussed.

An investigation of condensation heat transfer in a closed tube containing a soluble noncondensable gas

NASA Technical Reports Server (NTRS)

Saaski, E. W.; Hanson, R. J.

1976-01-01

An exact one-dimensional condensation heat transfer model for insoluble gases has been developed and compared with experimental data. Modifications to this model to accommodate soluble gas behavior have also been accomplished, and the effects on gas front behavior demonstrated. Analytical models for condensation heat transfer are documented, and a novel optical method used for measuring gas concentration profiles is outlined.

Exploration of bulk and interface behavior of gas molecules and 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid using equilibrium and nonequilibrium molecular dynamics simulation and quantum chemical calculation.

PubMed

Yang, Quan; Achenie, Luke E K

2018-04-18

Ionic liquids (ILs) show brilliant performance in separating gas impurities, but few researchers have performed an in-depth exploration of the bulk and interface behavior of penetrants and ILs thoroughly. In this research, we have performed a study on both molecular dynamics (MD) simulation and quantum chemical (QC) calculation to explore the transport of acetylene and ethylene in the bulk and interface regions of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]-[BF4]). The diffusivity, solubility and permeability of gas molecules in the bulk were researched with MD simulation first. The subdiffusion behavior of gas molecules is induced by coupling between the motion of gas molecules and the ions, and the relaxation processes of the ions after the disturbance caused by gas molecules. Then, QC calculation was performed to explore the optical geometry of ions, ion pairs and complexes of ions and penetrants, and interaction potential for pairs and complexes. Finally, nonequilibrium MD simulation was performed to explore the interface structure and properties of the IL-gas system and gas molecule behavior in the interface region. The research results may be used in the design of IL separation media.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, J.F.

1995-10-10

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode. 5 figs.

Thermochromatography and activation analysis

NASA Astrophysics Data System (ADS)

Stattarov, G. S.; Kist, A. A.

1999-01-01

Gas thermochromatography is a promising method in combination with neutron activation analysis. The procedure includes heating of irradiated samples in a stream of reacting gas carrier (air, chlorine, etc.) or heating in presence of compounds evolving gas at high temperatures. Gaseous products are passed through a tube with certain temperature gradient filled with various sorbents and the gases condense in different parts of the column. Studies of the processes of producing and trapping of volatile compounds allowed to work out various set-ups of apparatus with sorption tubes of various length and various temperature gradients, various filters, sorbents, etc. Sensitivity of these methods is sufficiently better then in INAA.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, John F.

1995-01-01

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode.

Planetary Surface Instruments Workshop

NASA Technical Reports Server (NTRS)

Meyer, Charles (Editor); Treiman, Allan H. (Editor); Kostiuk, Theodor (Editor)

1996-01-01

This report on planetary surface investigations and planetary landers covers: (1) the precise chemical analysis of solids; (2) isotopes and evolved gas analyses; (3) planetary interiors; planetary atmospheres from within as measured by landers; (4) mineralogical examination of extraterrestrial bodies; (5) regoliths; and (6) field geology/processes.

Translating Basic Behavioral and Social Science Research to Clinical Application: The EVOLVE Mixed Methods Approach

ERIC Educational Resources Information Center

Peterson, Janey C.; Czajkowski, Susan; Charlson, Mary E.; Link, Alissa R.; Wells, Martin T.; Isen, Alice M.; Mancuso, Carol A.; Allegrante, John P.; Boutin-Foster, Carla; Ogedegbe, Gbenga; Jobe, Jared B.

2013-01-01

Objective: To describe a mixed-methods approach to develop and test a basic behavioral science-informed intervention to motivate behavior change in 3 high-risk clinical populations. Our theoretically derived intervention comprised a combination of positive affect and self-affirmation (PA/SA), which we applied to 3 clinical chronic disease…

Salmonid behavior and water temperature

Treesearch

Sally T. Sauter; John McMillan; Jason B. Dunham

2001-01-01

Animals react not only to immediate changes in their environment but also to cues that signal long-term changes to which they must adapt to survive. A proximate factor stimulates an animal’s immediate behavioral response, whereas what is known as an ultimate factor causes an animal to adjust its behavior to evolving conditions, thereby increasing its fitness and...

Dual porosity gas evolving electrode

DOEpatents

Townsend, Carl W.

1994-01-01

A dual porosity electrode for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

Thermal Behavior and Structural Study of SiO₂/Poly(ε-caprolactone) Hybrids Synthesized via Sol-Gel Method.

PubMed

Vecchio Ciprioti, Stefano; Tuffi, Riccardo; Dell'Era, Alessandro; Dal Poggetto, Francesco; Bollino, Flavia

2018-02-10

SiO₂-based organic-inorganic hybrids (OIHs) are versatile materials whose properties may change significantly because of their thermal treatment. In fact, after their preparation at low temperature by the sol-gel method, they still have reactive silanol groups due to incomplete condensation reactions that can be removed by accelerating these processes upon heating them in controlled experimental conditions. In this study, the thermal behavior of pure SiO₂ and four SiO₂-based OIHs containing increasing amount (6, 12, 24 and 50 wt %) of poly(ε-caprolactone) (PCL) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanisms of thermally activated processes occurring upon heating. In particular, all samples already release ethanol at low temperature. Moreover, thermal degradation of PCL takes place in the richest-PCL sample, leading to 5-hexenoic acid, H₂O, CO₂, CO and ε-caprolactone. After the samples' treatment at 450, 600 and 1000 °C, the X-ray diffraction (XRD) spectra revealed that they were still amorphous, while the presence of cristobalite is found in the richest-PCL material.

Thermal Behavior and Structural Study of SiO2/Poly(ε-caprolactone) Hybrids Synthesized via Sol-Gel Method

PubMed Central

Tuffi, Riccardo; Dell’Era, Alessandro; Dal Poggetto, Francesco

2018-01-01

SiO2-based organic-inorganic hybrids (OIHs) are versatile materials whose properties may change significantly because of their thermal treatment. In fact, after their preparation at low temperature by the sol-gel method, they still have reactive silanol groups due to incomplete condensation reactions that can be removed by accelerating these processes upon heating them in controlled experimental conditions. In this study, the thermal behavior of pure SiO2 and four SiO2-based OIHs containing increasing amount (6, 12, 24 and 50 wt %) of poly(ε-caprolactone) (PCL) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanisms of thermally activated processes occurring upon heating. In particular, all samples already release ethanol at low temperature. Moreover, thermal degradation of PCL takes place in the richest-PCL sample, leading to 5-hexenoic acid, H2O, CO2, CO and ε-caprolactone. After the samples’ treatment at 450, 600 and 1000 °C, the X-ray diffraction (XRD) spectra revealed that they were still amorphous, while the presence of cristobalite is found in the richest-PCL material. PMID:29439383

Investigation of the coupling of the momentum distribution of a BEC with its collective of modes

NASA Astrophysics Data System (ADS)

Henn, Emanuel; Tavares, Pedro; Fritsch, Amilson; Vivanco, Franklin; Telles, Gustavo; Bagnato, Vanderlei

In our group we have a strong research line on quantum turbulence and the general investigation of Bose-Einstein condensates (BEC) subjected to oscillatory excitations. Inside this research line we investigate first the behavior of the normal modes of the BEC under this excitation and observe a non-linear behavior in the amplitude of the quadrupolar mode. Also, inside this same procedure of investigation we study the momentum distribution of a BEC to understand if it is possible to extract Kolmogorov like excitation spectra which would point to a turbulent state of matter. The condensate is perturbed, and we let it evolve in-trap after which we perform standard time-of- flight absorption imaging. The momentum distribution is extracted and analyzed as a function of the in-trap free evolution time for a 2D projected cloud. We show that the momentum distribution has its features varying periodically with the same frequency as the quadrupolar mode displayed by the atomic gas hinting at a strong coupling of both. The main consequence of that one cannot be assertive about the quantitative features of the extract spectrum of momentum and we can only rely on its qualitative features. Financial Support: FAPESP, CNPq.

Biodegradation – Monitored Natural Attenuation (MNA) for Oxygenates: How it Evolved, why it Occurs and Using Stable Carbon Isotopes to Predict Plume Behavior

EPA Science Inventory

The organisms that degrade MtBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

MNA for Chlorinated Solvents and Fuel Oxygenates: Why It Occurs, How It Evolved, and Using Stable Carbon Isotopes to Predict Plume Behavior

EPA Science Inventory

The organisms that degrade MtBE under anaerobic conditions are evolved to acquire energy for growth by using molecular hydrogen and carbonate ion to cleave methyl ether bonds. Methyl ether bonds are common in nature and the bond also occurs in MTBE. MTBE in contaminated ground...

Cognitive Adaptations for n-person Exchange: The Evolutionary Roots of Organizational Behavior.

PubMed

Tooby, John; Cosmides, Leda; Price, Michael E

2006-03-01

Organizations are composed of stable, predominantly cooperative interactions or n -person exchanges. Humans have been engaging in n -person exchanges for a great enough period of evolutionary time that we appear to have evolved a distinct constellation of species-typical mechanisms specialized to solve the adaptive problems posed by this form of social interaction. These mechanisms appear to have been evolutionarily elaborated out of the cognitive infrastructure that initially evolved for dyadic exchange. Key adaptive problems that these mechanisms are designed to solve include coordination among individuals, and defense against exploitation by free riders. Multi-individual cooperation could not have been maintained over evolutionary time if free riders reliably benefited more than contributors to collective enterprises, and so outcompeted them. As a result, humans evolved mechanisms that implement an aversion to exploitation by free riding, and a strategy of conditional cooperation, supplemented by punitive sentiment towards free riders. Because of the design of these mechanisms, how free riding is treated is a central determinant of the survival and health of cooperative organizations. The mapping of the evolved psychology of n -party exchange cooperation may contribute to the construction of a principled theoretical foundation for the understanding of human behavior in organizations.

Cognitive Adaptations for n-person Exchange: The Evolutionary Roots of Organizational Behavior

PubMed Central

Tooby, John; Cosmides, Leda; Price, Michael E.

2013-01-01

Organizations are composed of stable, predominantly cooperative interactions or n-person exchanges. Humans have been engaging in n-person exchanges for a great enough period of evolutionary time that we appear to have evolved a distinct constellation of species-typical mechanisms specialized to solve the adaptive problems posed by this form of social interaction. These mechanisms appear to have been evolutionarily elaborated out of the cognitive infrastructure that initially evolved for dyadic exchange. Key adaptive problems that these mechanisms are designed to solve include coordination among individuals, and defense against exploitation by free riders. Multi-individual cooperation could not have been maintained over evolutionary time if free riders reliably benefited more than contributors to collective enterprises, and so outcompeted them. As a result, humans evolved mechanisms that implement an aversion to exploitation by free riding, and a strategy of conditional cooperation, supplemented by punitive sentiment towards free riders. Because of the design of these mechanisms, how free riding is treated is a central determinant of the survival and health of cooperative organizations. The mapping of the evolved psychology of n-party exchange cooperation may contribute to the construction of a principled theoretical foundation for the understanding of human behavior in organizations. PMID:23814325

Fragmentation during primordial star formation

NASA Astrophysics Data System (ADS)

Dutta, Jayanta

Understanding the physics of the very first stars in the universe, the so-called Population III (or Pop III) stars, is crucial in determining how the universe evolved into what we observe today. In the standard model of Pop III star formation, the baryonic matter, mainly atomic hydrogen, collapses gravitationally into small Dark Matter (DM) minihalos. However, so far there is little understanding on how the thermal, dynamical and chemical evolution of the primordial gas depend on the initial configuration of the minihalos (for example, rotation of the unstable clumps inside minihalos, turbulence, formation of molecular hydrogen and cosmic variance of the minihalos). We use the modified version of the Gadget-2 code, a three-dimensional smoothed particle hydrodynamics (SPH) simulations, to follow the evolution of the collapsing gas in both idealized as well as more realistic minihalos. Unlike some earlier cosmological calculations, the implementation of sink particles allows us to follow the evolution of the accretion disk that builds up in the centre of each minihalo and fragments. We find that the fragmentation behavior depends on the adopted choice of three-body H2 formation rate coefficient. The increasing cooling rate during rapid conversion of the atomic to molecular hydrogen is offset by the heating due to gas contraction. We propose that the H2 cooling, the heating due to H2 formation and compressional heating together set a density and temperature structure in the disk that favors fragmentation. We also find that the cloud's initial degree of rotation has a significant effect on the thermal and dynamical evolution of the collapsing gas. Clouds with higher rotation exhibit spiral-arm-like structures that become gravitationally unstable to fragmentation on several scales. These type of clouds tend to fragment more and have lower accretion rates compared to their slowly rotating counterparts. In addition, we find that the distribution of specific angular momentum (L) of the gas follows a power-law relation with the enclosed gas mass (M), L ∝ M1.125, which is controlled by the gravitational and pressure torque, and does not depend on the cloud's initial degree of rotation and turbulence.

Coalition Factor in the Evolution of Non-Kin Altruism

NASA Astrophysics Data System (ADS)

Dessalles, Jean-Louis

Animal behavior is often altruistic. In the frame of the theory of natural selection, altruism can only exist under specific conditions like kin selection or reciprocal cooperation. We show that reciprocal cooperation, which is generally invoked to explain non-kin altruism, requires very restrictive conditions to be stable. Some of these conditions are not met in many cases of altruism observed in nature. In search of another explanation of non-kin altruism, we consider Zahavis's theory of prestige. We extend it to propose a "political" model of altruism. We give evidence showing that non-kin altruism can evolve in the context of inter-subgroup competition. Under such circumstances, altruistic behavior can be used by individuals to advertise their quality as efficient coalition members. In this model, only abilities which positively correlate with the subgroup success can evolve into altruistic behaviors.

The mechanism of sound production in túngara frogs and its role in sexual selection and speciation.

PubMed

Ryan, Michael J; Guerra, Mónica A

2014-10-01

Sexual communication can evolve in response to sexual selection, and it can also cause behavioral reproductive isolation between populations and thus drive speciation. Anurans are an excellent system to investigate these links between behavior and evolution because we have detailed knowledge of how neural mechanisms generate behavioral preferences for calls and how these preferences then generate selection on call variation. But we know far less about the physical mechanisms of call production, especially how different laryngeal morphologies generate call variation. Here we review studies of a group of species that differ in the presence of a secondary call component that evolved under sexual selection. We discuss how the larynx produces this call component, and how laryngeal morphology generates sexual selection and can contribute to speciation. Copyright © 2014. Published by Elsevier Ltd.

Transient Evolutional Dynamics of Quantum-Dot Molecular Phase Coherence for Sensitive Optical Switching

NASA Astrophysics Data System (ADS)

Shen, Jian Qi; Gu, Jing

2018-04-01

Atomic phase coherence (quantum interference) in a multilevel atomic gas exhibits a number of interesting phenomena. Such an atomic quantum coherence effect can be generalized to a quantum-dot molecular dielectric. Two quantum dots form a quantum-dot molecule, which can be described by a three-level Λ-configuration model { |0> ,|1> ,|2> } , i.e., the ground state of the molecule is the lower level |0> and the highly degenerate electronic states in the two quantum dots are the two upper levels |1> ,|2> . The electromagnetic characteristics due to the |0>-|1> transition can be controllably manipulated by a tunable gate voltage (control field) that drives the |2>-|1> transition. When the gate voltage is switched on, the quantum-dot molecular state can evolve from one steady state (i.e., |0>-|1> two-level dressed state) to another steady state (i.e., three-level coherent-population-trapping state). In this process, the electromagnetic characteristics of a quantum-dot molecular dielectric, which is modified by the gate voltage, will also evolve. In this study, the transient evolutional behavior of the susceptibility of a quantum-dot molecular thin film and its reflection spectrum are treated by using the density matrix formulation of the multilevel systems. The present field-tunable and frequency-sensitive electromagnetic characteristics of a quantum-dot molecular thin film, which are sensitive to the applied gate voltage, can be utilized to design optical switching devices.

An investigation of condensation heat transfer in a closed tube containing a soluble noncondensable gas

NASA Technical Reports Server (NTRS)

Saaski, E. W.; Hanson, R. J.

1976-01-01

A more exact one-dimensional condensation heat transfer model for insoluble gases was developed and compared with experimental data. Modifications to this model to accommodate soluble gas behavior were also accomplished, and the effects on gas front behavior demonstrated. Analytical models for condensation heat transfer are documented, and an optical method used for measuring gas concentration profiles is outlined. Experimental data is then presented and interpreted.

Behavior of bubbles in glassmelts. III - Dissolution and growth of a rising bubble containing a single gas

NASA Technical Reports Server (NTRS)

Onorato, P. I. K.; Weinberg, M. C.; Uhlmann, D. R.

1981-01-01

Finite difference solutions of the mass transport equations governing the dissolution (growth) of a rising gas bubble, containing a single gas, in a glassmelt were obtained. These solutions were compared with those obtained from an approximate procedure for a range of the controlling parameters. Applications were made to describe various aspects of O2 and CO2 gas-bubble behavior in a soda-lime-silicate melt.

Ideal gas behavior of a strongly coupled complex (dusty) plasma.

PubMed

Oxtoby, Neil P; Griffith, Elias J; Durniak, Céline; Ralph, Jason F; Samsonov, Dmitry

2013-07-05

In a laboratory, a two-dimensional complex (dusty) plasma consists of a low-density ionized gas containing a confined suspension of Yukawa-coupled plastic microspheres. For an initial crystal-like form, we report ideal gas behavior in this strongly coupled system during shock-wave experiments. This evidence supports the use of the ideal gas law as the equation of state for soft crystals such as those formed by dusty plasmas.

Structural properties and gas sensing behavior of sol-gel grown nanostructured zinc oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajyaguru, Bhargav; Gadani, Keval; Kansara, S. B.

2016-05-06

In this communication, we report the results of the studies on structural properties and gas sensing behavior of nanostructured ZnO grown using acetone precursor based modified sol-gel technique. Final product of ZnO was sintered at different temperatures to vary the crystallite size while their structural properties have been studied using X-ray diffraction (XRD) measurement performed at room temperature. XRD results suggest the single phasic nature of all the samples and crystallite size increases from 11.53 to 20.96 nm with increase in sintering temperature. Gas sensing behavior has been studied for acetone gas which indicates that lower sintered samples are moremore » capable to sense the acetone gas and related mechanism has been discussed in the light of crystallite size, crystal boundary density, defect mechanism and possible chemical reaction between gas traces and various oxygen species.« less

Behavior and dynamics of bubble breakup in gas pipeline leaks and accidental subsea oil well blowouts.

PubMed

Wang, Binbin; Socolofsky, Scott A; Lai, Chris C K; Adams, E Eric; Boufadel, Michel C

2018-06-01

Subsea oil well blowouts and pipeline leaks release oil and gas to the environment through vigorous jets. Predicting the breakup of the released fluids in oil droplets and gas bubbles is critical to predict the fate of petroleum compounds in the marine water column. To predict the gas bubble size in oil well blowouts and pipeline leaks, we observed and quantified the flow behavior and breakup process of gas for a wide range of orifice diameters and flow rates. Flow behavior at the orifice transitions from pulsing flow to continuous discharge as the jet crosses the sonic point. Breakup dynamics transition from laminar to turbulent at a critical value of the Weber number. Very strong pure gas jets and most gas/liquid co-flowing jets exhibit atomization breakup. Bubble sizes in the atomization regime scale with the jet-to-plume transition length scale and follow -3/5 power-law scaling for a mixture Weber number. Copyright © 2018 Elsevier Ltd. All rights reserved.

Steampunk: Full Steam Ahead

ERIC Educational Resources Information Center

Campbell, Heather M.

2010-01-01

Steam-powered machines, anachronistic technology, clockwork automatons, gas-filled airships, tentacled monsters, fob watches, and top hats--these are all elements of steampunk. Steampunk is both speculative fiction that imagines technology evolved from steam-powered cogs and gears--instead of from electricity and computers--and a movement that…

Evolution and development of fetal membranes and placentation in amniote vertebrates.

PubMed

Ferner, Kirsten; Mess, Andrea

2011-08-31

We review aspects of fetal membrane evolution and patterns of placentation within amniotes, the most successful land vertebrates. Special reference is given to embryonic gas supply. The evolution of fetal membranes is a prerequisite for reproduction independent from aquatic environments. Starting from a basically similar repertoire of fetal membranes - the amnion, chorion, allantois and yolk sac, which form the cleidoic egg - different structural solutions for embryonic development have evolved. In oviparous amniotes the chorioallantoic membrane is the major site for the exchange of respiratory gases between fetus and outer environment. The richly vascularised yolk sac and allantois in concert with the chorion play an important role in the evolution of placentation in various viviparous amniotes. Highly complex placentas have evolved independently among squamate sauropsids and in marsupial and placental mammals. In conclusion, there seems to be a natural force to improve gas exchange processes in intrauterine environments by reducing the barrier between the blood systems and optimising the exchange areas. Copyright © 2011 Elsevier B.V. All rights reserved.

SUPERNOVAE AND THEIR EXPANDING BLAST WAVES DURING THE EARLY EVOLUTION OF GALACTIC GLOBULAR CLUSTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tenorio-Tagle, Guillermo; Silich, Sergiy; Muñoz-Tuñón, Casiana

2015-11-20

Our arguments deal with the early evolution of Galactic globular clusters and show why only a few of the supernovae (SNe) products were retained within globular clusters and only in the most massive cases (M ≥ 10{sup 6} M{sub ⊙}), while less massive clusters were not contaminated at all by SNe. Here, we show that SN blast waves evolving in a steep density gradient undergo blowout and end up discharging their energy and metals into the medium surrounding the clusters. This inhibits the dispersal and the contamination of the gas left over from a first stellar generation. Only the ejecta from well-centeredmore » SNe that evolve into a high-density medium available for a second stellar generation (2SG) in the most massive clusters would be retained. These are likely to mix their products with the remaining gas, eventually leading in these cases to an Fe-contaminated 2SG.« less

A DTA/GC for the in Situ Identification of the Martian Surface Material

NASA Technical Reports Server (NTRS)

Mancinelli, R. L.; White, M. R.; Orenberg, J. B.

1993-01-01

The composition and mineralogy of the Martian surface material remain largely unknown. To determine its composition and mineralogy, several techniques are being considered for in situ analyses of the Martian surface material during missions to Mars. We have successfully developed, constructed, and tested a laboratory DTA/GC. The DTA is a Dupont model 1600 high temperature DTA coupled with a GC equipped with a MID detector. The system is operated by a Sun Sparc 11 workstation. When gas evolves during a thermal chemical event, it is shunted into the GC and the temperature is recorded in association with the specific thermal event. We have used this laboratory instrument to define experimental criteria necessary for determining the composition and mineralogy of the Martian surface in situ (e.g., heating of sample to 1100 C to distinguish clays). Our studies indicate that DTA/GC will provide a broad spectrum of mineralogical and evolved gas data pertinent to exobiology, geochemistry, and geology.

Application of ion-induced nucleation mass spectrometry in the analysis of trace gases evolved from a polyimide film during the thermal curing stages

NASA Technical Reports Server (NTRS)

Smith, A. C.

1982-01-01

Trace gases evolved from a polyimide film during its thermal curing stages have been studied using ion-induced nucleation mass spectrometry. The technique involved exposing the test gas sample to a low energy beta source and recording the masses of the ion-induced molecular clusters formed in the reaction chamber. On the basis of the experimentally observed molecular cluster spectra, it has been concluded that the dominant trace component had a molecular weight of 87 atomic mass units. This component has been identified as a molecule of dimethylacetamide (DMAC) which had been used as a solvent in the preparation of the test polyimide specimen. This identification has been further confirmed by comparing the spectra of the test gas sample and the DMAC calibration sample obtained with a conventional mass spectrometer. The advantages of the ion-induced nucleation mass spectrometer versus the conventional mass spectrometer are discussed.

Cosmic Collisions: Galaxy Mergers and Evolution

NASA Astrophysics Data System (ADS)

Trouille, Laura; Willett, Kyle; Masters, Karen; Lintott, Christopher; Whyte, Laura; Lynn, Stuart; Tremonti, Christina A.

2014-08-01

Over the years evidence has mounted for a significant mode of galaxy evolution via mergers. This process links gas-rich, spiral galaxies; starbursting galaxies; active galactic nuclei (AGN); post-starburst galaxies; and gas-poor, elliptical galaxies, as objects representing different phases of major galaxy mergers. The post-starburst phase is particularly interesting because nearly every galaxy that evolves from star-forming to quiescent must pass through it. In essence, this phase is a sort of galaxy evolution “bottleneck” that indicates that a galaxy is actively evolving through important physical transitions. In this talk I will present the results from the ‘Galaxy Zoo Quench’ project - using post-starburst galaxies to place observational constraints on the role of mergers and AGN activity in quenching star formation. `Quench’ is the first fully collaborative research project with Zooniverse citizen scientists online; engaging the public in all phases of research, from classification to data analysis and discussion to writing the article and submission to a refereed journal.

Evaluation of hydrogen as a cryogenic wind tunnel test gas

NASA Technical Reports Server (NTRS)

Haut, R. C.

1977-01-01

The nondimensional ratios used to describe various flow situations in hydrogen were determined and compared with the corresponding ideal diatomic gas ratios. The results were used to examine different inviscid flow configurations. The relatively high value of the characteristic rotational temperature causes the behavior of hydrogen, under cryogenic conditions, to deviate substantially from the behavior of an ideal diatomic gas in the compressible flow regime. Therefore, if an idea diatomic gas is to be modeled, cryogenic hydrogen is unacceptable as a wind tunnel test gas in a compressible flow situation.

Behavioral resilience in the post-genomic era: emerging models linking genes with environment

PubMed Central

Rende, Richard

2012-01-01

One of the most important deliverables of the post-genomic era has been a new and nuanced appreciation of how the environment shapes—and holds potential to alter—the expression of susceptibility genes for behavioral dimensions and disorders. This paper will consider three themes that have emerged from cutting-edge research studies that utilize newer molecular genetic approaches as well as tried-and-true genetic epidemiological methodologies, with particular reference to evolving perspectives on resilience and plasticity. These themes are: (1) evidence for replicable and robust shared environmental effects on a number of clinically relevant behaviors in childhood and adolescence; (2) evolving research on gene-environment interaction; and (3) a newer focus on differential susceptibility and plasticity. The net sum of these themes is that consideration of genetic effects on behavioral dimensions and disorders needs to be connected to thinking about the role of environment as a potent source for promoting resilience and change. PMID:22461772

Mice repeatedly exposed to Group-A β-Haemolytic Streptococcus show perseverative behaviors, impaired sensorimotor gating, and immune activation in rostral diencephalon

PubMed Central

Macrì, Simone; Ceci, Chiara; Onori, Martina Proietti; Invernizzi, Roberto William; Bartolini, Erika; Altabella, Luisa; Canese, Rossella; Imperi, Monica; Orefici, Graziella; Creti, Roberta; Margarit, Immaculada; Magliozzi, Roberta; Laviola, Giovanni

2015-01-01

Repeated exposure to Group-A β-Haemolytic Streptococcus (GAS) may constitute a vulnerability factor in the onset and course of pediatric motor disturbances. GAS infections/colonization can stimulate the production of antibodies, which may cross the blood brain barrier, target selected brain areas (e.g. basal ganglia), and exacerbate motor alterations. Here, we exposed developing SJL male mice to four injections with a GAS homogenate and evaluated the following domains: motor coordination; general locomotion; repetitive behaviors; perseverative responses; and sensorimotor gating (pre-pulse inhibition, PPI). To demonstrate that behavioral changes were associated with immune-mediated brain alterations, we analyzed, in selected brain areas, the presence of infiltrates and microglial activation (immunohistochemistry), monoamines (HPLC), and brain metabolites (in vivo Magnetic Resonance Spectroscopy). GAS-exposed mice showed increased repetitive and perseverative behaviors, impaired PPI, and reduced concentrations of serotonin in prefrontal cortex, a brain area linked to the behavioral domains investigated, wherein they also showed remarkable elevations in lactate. Active inflammatory processes were substantiated by the observation of infiltrates and microglial activation in the white matter of the anterior diencephalon. These data support the hypothesis that repeated GAS exposure may elicit inflammatory responses in brain areas involved in motor control and perseverative behavior, and result in phenotypic abnormalities. PMID:26304458

Mice repeatedly exposed to Group-A β-Haemolytic Streptococcus show perseverative behaviors, impaired sensorimotor gating, and immune activation in rostral diencephalon.

PubMed

Macrì, Simone; Ceci, Chiara; Onori, Martina Proietti; Invernizzi, Roberto William; Bartolini, Erika; Altabella, Luisa; Canese, Rossella; Imperi, Monica; Orefici, Graziella; Creti, Roberta; Margarit, Immaculada; Magliozzi, Roberta; Laviola, Giovanni

2015-08-25

Repeated exposure to Group-A β-Haemolytic Streptococcus (GAS) may constitute a vulnerability factor in the onset and course of pediatric motor disturbances. GAS infections/colonization can stimulate the production of antibodies, which may cross the blood brain barrier, target selected brain areas (e.g. basal ganglia), and exacerbate motor alterations. Here, we exposed developing SJL male mice to four injections with a GAS homogenate and evaluated the following domains: motor coordination; general locomotion; repetitive behaviors; perseverative responses; and sensorimotor gating (pre-pulse inhibition, PPI). To demonstrate that behavioral changes were associated with immune-mediated brain alterations, we analyzed, in selected brain areas, the presence of infiltrates and microglial activation (immunohistochemistry), monoamines (HPLC), and brain metabolites (in vivo Magnetic Resonance Spectroscopy). GAS-exposed mice showed increased repetitive and perseverative behaviors, impaired PPI, and reduced concentrations of serotonin in prefrontal cortex, a brain area linked to the behavioral domains investigated, wherein they also showed remarkable elevations in lactate. Active inflammatory processes were substantiated by the observation of infiltrates and microglial activation in the white matter of the anterior diencephalon. These data support the hypothesis that repeated GAS exposure may elicit inflammatory responses in brain areas involved in motor control and perseverative behavior, and result in phenotypic abnormalities.

Steps Towards Understanding Large-scale Deformation of Gas Hydrate-bearing Sediments

NASA Astrophysics Data System (ADS)

Gupta, S.; Deusner, C.; Haeckel, M.; Kossel, E.

2016-12-01

Marine sediments bearing gas hydrates are typically characterized by heterogeneity in the gas hydrate distribution and anisotropy in the sediment-gas hydrate fabric properties. Gas hydrates also contribute to the strength and stiffness of the marine sediment, and any disturbance in the thermodynamic stability of the gas hydrates is likely to affect the geomechanical stability of the sediment. Understanding mechanisms and triggers of large-strain deformation and failure of marine gas hydrate-bearing sediments is an area of extensive research, particularly in the context of marine slope-stability and industrial gas production. The ultimate objective is to predict severe deformation events such as regional-scale slope failure or excessive sand production by using numerical simulation tools. The development of such tools essentially requires a careful analysis of thermo-hydro-chemo-mechanical behavior of gas hydrate-bearing sediments at lab-scale, and its stepwise integration into reservoir-scale simulators through definition of effective variables, use of suitable constitutive relations, and application of scaling laws. One of the focus areas of our research is to understand the bulk coupled behavior of marine gas hydrate systems with contributions from micro-scale characteristics, transport-reaction dynamics, and structural heterogeneity through experimental flow-through studies using high-pressure triaxial test systems and advanced tomographical tools (CT, ERT, MRI). We combine these studies to develop mathematical model and numerical simulation tools which could be used to predict the coupled hydro-geomechanical behavior of marine gas hydrate reservoirs in a large-strain framework. Here we will present some of our recent results from closely co-ordinated experimental and numerical simulation studies with an objective to capture the large-deformation behavior relevant to different gas production scenarios. We will also report on a variety of mechanically relevant test scenarios focusing on effects of dynamic changes in gas hydrate saturation, highly uneven gas hydrate distributions, focused fluid migration and gas hydrate production through depressurization and CO2 injection.

Methods to produce calibration mixtures for anesthetic gas monitors and how to perform volumetric calculations on anesthetic gases.

PubMed

Christensen, P L; Nielsen, J; Kann, T

1992-10-01

A simple procedure for making calibration mixtures of oxygen and the anesthetic gases isoflurane, enflurane, and halothane is described. One to ten grams of the anesthetic substance is evaporated in a closed, 11,361-cc glass bottle filled with oxygen gas at atmospheric pressure. The carefully mixed gas is used to calibrate anesthetic gas monitors. By comparison of calculated and measured volumetric results it is shown that at atmospheric conditions the volumetric behavior of anesthetic gas mixtures can be described with reasonable accuracy using the ideal gas law. A procedure is described for calculating the deviation from ideal gas behavior in cases in which this is needed.

X-ray Scaling Relations of Early Type Galaxies

NASA Astrophysics Data System (ADS)

Kim, Dong-Woo

2015-08-01

We will review recent results of the X-ray scaling relations of early type galaxies. With high quality Chandra X-ray data, the properties (Lx and T) of hot ISM are accurately measured from gas-poor to gas-rich galaxies. We found a strong correlation between Lx(gas) and M(total) among ETGs with independently measured M(total), indicating that the total mass is the primary factor in regulating the amount of hot gas. We found a tight correlation between Lx(gas) and T(gas) among normal (non-cD), genuine (passively evolving, sigma-supported) ellipticals. This relation holds in a large range of Lx (several 1038 - a few 1041 erg/s). While this relation can be understood among gas-rich galaxies (Lx > 1040 erg/s) as a consequence of virialized gaseous halos in the dark matter potentials, the same tight relation is unexpected among gas-poor galaxies where the hot gas is in a wind/outflow state. We also found an interesting difference between cDs and giant Es, the former having an order of magnitude higher Lx(gas) with a similar T(gas). We will discuss the implications of our results by comparing with other observations of galaxies/groups and recent simulations.

Hubble Observes One-of-a-Kind Star Nicknamed ‘Nasty’

NASA Image and Video Library

2015-03-21

Astronomers using NASA’s Hubble Space Telescope have uncovered surprising new clues about a hefty, rapidly aging star whose behavior has never been seen before in our Milky Way galaxy. In fact, the star is so weird that astronomers have nicknamed it “Nasty 1,” a play on its catalog name of NaSt1. The star may represent a brief transitory stage in the evolution of extremely massive stars. First discovered several decades ago, Nasty 1 was identified as a Wolf-Rayet star, a rapidly evolving star that is much more massive than our sun. The star loses its hydrogen-filled outer layers quickly, exposing its super-hot and extremely bright helium-burning core. But Nasty 1 doesn’t look like a typical Wolf-Rayet star. The astronomers using Hubble had expected to see twin lobes of gas flowing from opposite sides of the star, perhaps similar to those emanating from the massive star Eta Carinae, which is a Wolf-Rayet candidate. Instead, Hubble revealed a pancake-shaped disk of gas encircling the star. The vast disk is nearly 2 trillion miles wide, and may have formed from an unseen companion star that snacked on the outer envelope of the newly formed Wolf-Rayet. Based on current estimates, the nebula surrounding the stars is just a few thousand years old, and as close as 3,000 light-years from Earth. Credits: NASA/Hubble

The Evolution of "Enhanced" Cognitive Behavior Therapy for Eating Disorders: Learning from Treatment Nonresponse

ERIC Educational Resources Information Center

Cooper, Zafra; Fairburn, Christopher G.

2011-01-01

In recent years there has been widespread acceptance that cognitive behavior therapy (CBT) is the treatment of choice for bulimia nervosa. The cognitive behavioral treatment of bulimia nervosa (CBT-BN) was first described in 1981. Over the past decades the theory and treatment have evolved in response to a variety of challenges. The treatment has…

Evolution of the Behavioral Sciences Branch of the Space Medicine and Health Care Systems Office at the Johnson Space Center.

PubMed

Fiedler, Edna R; Carpenter, Frank E

2005-06-01

This paper presents a brief history of psychology and psychiatry roles in psychological selection and how these roles have evolved into the Behavioral Sciences Branch at the Johnson Space Center USC), Houston, TX. Since the initial selection of the Mercury Seven, the first United States astronauts, psychologists and psychiatrists have been involved in astronaut selection activities. Initially very involved in psychological selection of astronauts, the role of behavioral health specialists waned during the Gemini and Apollo years. With the onset of the NASA/Mir/International Space Station Program, the introduction of payload and mission specialists, and international collaboration, the evolving need for behavioral health expertise became apparent. Medical and psychological selection processes were revisited and the Johnson Space Center developed a separate operational unit focused on behavioral health and performance. This work unit eventually became the Behavioral Sciences branch of the Space Medicine and Health Care Systems Office. Research was allocated across groups at JSC, other NASA space centers, and the National Space Biomedical Research Institute, and was funded by NASA Headquarters. The current NASA focus on human space exploration to the Moon and beyond re-emphasizes the importance of the human-centered approach.

Uncertainty and sensitivity analysis of fission gas behavior in engineering-scale fuel modeling

DOE PAGES

Pastore, Giovanni; Swiler, L. P.; Hales, Jason D.; ...

2014-10-12

The role of uncertainties in fission gas behavior calculations as part of engineering-scale nuclear fuel modeling is investigated using the BISON fuel performance code and a recently implemented physics-based model for the coupled fission gas release and swelling. Through the integration of BISON with the DAKOTA software, a sensitivity analysis of the results to selected model parameters is carried out based on UO2 single-pellet simulations covering different power regimes. The parameters are varied within ranges representative of the relative uncertainties and consistent with the information from the open literature. The study leads to an initial quantitative assessment of the uncertaintymore » in fission gas behavior modeling with the parameter characterization presently available. Also, the relative importance of the single parameters is evaluated. Moreover, a sensitivity analysis is carried out based on simulations of a fuel rod irradiation experiment, pointing out a significant impact of the considered uncertainties on the calculated fission gas release and cladding diametral strain. The results of the study indicate that the commonly accepted deviation between calculated and measured fission gas release by a factor of 2 approximately corresponds to the inherent modeling uncertainty at high fission gas release. Nevertheless, higher deviations may be expected for values around 10% and lower. Implications are discussed in terms of directions of research for the improved modeling of fission gas behavior for engineering purposes.« less

Evolving Expert Knowledge Bases: Applications of Crowdsourcing and Serious Gaming to Advance Knowledge Development for Intelligent Tutoring Systems

ERIC Educational Resources Information Center

Floryan, Mark

2013-01-01

This dissertation presents a novel effort to develop ITS technologies that adapt by observing student behavior. In particular, we define an evolving expert knowledge base (EEKB) that structures a domain's information as a set of nodes and the relationships that exist between those nodes. The structure of this model is not the particularly novel…

Sex Ratio Bias Leads to the Evolution of Sex Role Reversal in Honey Locust Beetles.

PubMed

Fritzsche, Karoline; Booksmythe, Isobel; Arnqvist, Göran

2016-09-26

The reversal of conventional sex roles was enigmatic to Darwin, who suggested that it may evolve when sex ratios are female biased [1]. Here we present direct evidence confirming Darwin's hypothesis. We investigated mating system evolution in a sex-role-reversed beetle (Megabruchidius dorsalis) using experimental evolution under manipulated sex ratios and food regimes. In female-biased populations, where reproductive competition among females was intensified, females evolved to be more attractive and the sex roles became more reversed. Interestingly, female-specific mating behavior evolved more rapidly than male-specific mating behavior. We show that sexual selection due to reproductive competition can be strong in females and can target much the same traits as in males of species with conventional mating systems. Our study highlights two central points: the role of ecology in directing sexual selection and the role that females play in mating system evolution. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Co-evolution of Honesty and Strategic Vigilance

PubMed Central

Heintz, Christophe; Karabegovic, Mia; Molnar, Andras

2016-01-01

We hypothesize that when honesty is not motivated by selfish goals, it reveals social preferences that have evolved for convincing strategically vigilant partners that one is a person worth cooperating with. In particular, we explain how the patterns of dishonest behavior observed in recent experiments can be motivated by preferences for social and self-esteem. These preferences have evolved because they are adaptive in an environment where it is advantageous to be selected as a partner by others and where these others are strategically vigilant: they efficiently evaluate the expected benefit of cooperating with specific partners and attend to their intentions. We specify the adaptive value of strategic vigilance and preferences for social and self-esteem. We argue that evolved preferences for social and self-esteem are satisfied by applying mechanisms of strategic vigilance to one's own behavior. We further argue that such cognitive processes obviate the need for the evolution of preferences for fairness and social norm compliance. PMID:27790162

A mysterious dust clump in a disk around an evolved binary star system.

PubMed

Jura, M; Turner, J

1998-09-10

The discovery of planets in orbit around the pulsar PSR1257+12 shows that planets may form around post-main-sequence stars. Other evolved stars, such as HD44179 (an evolved star which is part of the binary system that has expelled the gas and dust that make the Red Rectangle nebula), possess gravitationally bound orbiting dust disks. It is possible that planets might form from gravitational collapse in such disks. Here we report high-angular-resolution observations at millimetre and submillimetre wavelengths of the dusk disk associated with the Red Rectangle. We find a dust clump with an estimated mass near that of Jupiter in the outer region of the disk. The clump is larger than our Solar System, and far beyond where planet formation would normally be expected, so its nature is at present unclear.

Dissociation behavior of methane--ethane mixed gas hydrate coexisting structures I and II.

PubMed

Kida, Masato; Jin, Yusuke; Takahashi, Nobuo; Nagao, Jiro; Narita, Hideo

2010-09-09

Dissociation behavior of methane-ethane mixed gas hydrate coexisting structures I and II at constant temperatures less than 223 K was studied with use of powder X-ray diffraction and solid-state (13)C NMR techniques. The diffraction patterns at temperatures less than 203 K showed both structures I and II simultaneously convert to Ih during the dissociation, but the diffraction pattern at temperatures greater than 208 K showed different dissociation behavior between structures I and II. Although the diffraction peaks from structure II decreased during measurement at constant temperatures greater than 208 K, those from structure I increased at the initial step of dissociation and then disappeared. This anomalous behavior of the methane-ethane mixed gas hydrate coexisting structures I and II was examined by using the (13)C NMR technique. The (13)C NMR spectra revealed that the anomalous behavior results from the formation of ethane-rich structure I. The structure I hydrate formation was associated with the dissociation rate of the initial methane-ethane mixed gas hydrate.

The cGAS-STING Defense Pathway and Its Counteraction by Viruses.

PubMed

Ma, Zhe; Damania, Blossom

2016-02-10

Upon virus infection, host cells mount a concerted innate immune response involving type I interferon and pro-inflammatory cytokines to enable elimination of the pathogen. Recently, cGAS and STING have been identified as intracellular sensors that activate the interferon pathway in response to virus infection and thus mediate host defense against a range of DNA and RNA viruses. Here we review how viruses are sensed by the cGAS-STING signaling pathway as well as how viruses modulate this pathway. Mechanisms utilized by viral proteins to inhibit cGAS and/or STING are also discussed. On the flip side, host cells have also evolved strategies to thwart viral immune escape. The balance between host immune control and viral immune evasion is pivotal to viral pathogenesis, and we discuss this virus-host stand-off in the context of the cGAS-STING innate immune pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

Recent progress on gas sensor based on quantum cascade lasers and hollow fiber waveguides

NASA Astrophysics Data System (ADS)

Liu, Ningwu; Sun, Juan; Deng, Hao; Ding, Junya; Zhang, Lei; Li, Jingsong

2017-02-01

Mid-infrared laser spectroscopy provides an ideal platform for trace gas sensing applications. Despite this potential, early MIR sensing applications were limited due to the size of the involved optical components, e.g. light sources and sample cells. A potential solution to this demand is the integration of hollow fiber waveguide with novelty quantum cascade lasers.Recently QCLs had great improvements in power, efficiency and wavelength range, which made the miniaturized platforms for gas sensing maintaining or even enhancing the achievable sensitivity conceivable. So that the miniaturization of QCLs and HWGs can be evolved into a mini sensor, which may be tailored to a variety of real-time and in situ applications ranging from environmental monitoring to workplace safety surveillance. In this article, we introduce QCLs and HWGs, display the applications of HWG based on QCL gas sensing and discuss future strategies for hollow fiber coupled quantum cascade laser gas sensor technology.

Female extrapair mating behavior can evolve via indirect selection on males

PubMed Central

Forstmeier, Wolfgang; Martin, Katrin; Bolund, Elisabeth; Schielzeth, Holger; Kempenaers, Bart

2011-01-01

In many species that form socially monogamous pair bonds, a considerable proportion of the offspring is sired by extrapair males. This observation has remained a puzzle for evolutionary biologists: although mating outside the pair bond can obviously increase the offspring production of males, the benefits of such behavior to females are less clear, yet females are known to actively solicit extrapair copulations. For more than two decades adaptionist explanations have dominated the discussions, yet remain controversial, and genetic constraint arguments have been dismissed without much consideration. An intriguing but still untested hypothesis states that extrapair mating behavior by females may be affected by the same genetic variants (alleles) as extrapair mating behavior by males, such that the female behavior could evolve through indirect selection on the male behavior. Here we show that in the socially monogamous zebra finch, individual differences in extrapair mating behavior have a hereditary component. Intriguingly, this genetic basis is shared between the sexes, as shown by a strong genetic correlation between male and female measurements of extrapair mating behavior. Hence, positive selection on males to sire extrapair young will lead to increased extrapair mating by females as a correlated evolutionary response. This behavior leads to a fundamentally different view of female extrapair mating: it may exist even if females obtain no net benefit from it, simply because the corresponding alleles were positively selected in the male ancestors. PMID:21670288

Small gas turbine engine technology

NASA Technical Reports Server (NTRS)

Niedzwiecki, Richard W.; Meitner, Peter L.

1988-01-01

Performance of small gas turbine engines in the 250 to 1,000 horsepower size range is significantly lower than that of large engines. Engines of this size are typically used in rotorcraft, commutercraft, general aviation, and cruise missile applications. Principal reasons for the lower efficiencies of a smaller engine are well known: component efficients are lower by as much as 8 to 10 percentage points because of size effects. Small engines are designed for lower cycle pressures and temperatures because of smaller blading and cooling limitations. The highly developed analytical and manufacturing techniques evolved for large engines are not directly transferrable to small engines. Thus, it was recognized that a focused effort addressing technologies for small engies was needed and could significantly impact their performance. Recently, in-house and contract studies were undertaken at the NASA Lewis Research Center to identify advanced engine cycle and component requirements for substantial performance improvement of small gas turbines for projected year 2000 applications. The results of both in-house research and contract studies are presented. In summary, projected fuel savings of 22 to 42 percent could be obtained. Accompanying direct operating cost reductions of 11 to 17 percent, depending on fuel cost, were also estimated. High payoff technologies are identified for all engine applications, and recent results of experimental research to evolve the high payoff technologies are described.

Optimal allocation of leaf epidermal area for gas exchange.

PubMed

de Boer, Hugo J; Price, Charles A; Wagner-Cremer, Friederike; Dekker, Stefan C; Franks, Peter J; Veneklaas, Erik J

2016-06-01

A long-standing research focus in phytology has been to understand how plants allocate leaf epidermal space to stomata in order to achieve an economic balance between the plant's carbon needs and water use. Here, we present a quantitative theoretical framework to predict allometric relationships between morphological stomatal traits in relation to leaf gas exchange and the required allocation of epidermal area to stomata. Our theoretical framework was derived from first principles of diffusion and geometry based on the hypothesis that selection for higher anatomical maximum stomatal conductance (gsmax ) involves a trade-off to minimize the fraction of the epidermis that is allocated to stomata. Predicted allometric relationships between stomatal traits were tested with a comprehensive compilation of published and unpublished data on 1057 species from all major clades. In support of our theoretical framework, stomatal traits of this phylogenetically diverse sample reflect spatially optimal allometry that minimizes investment in the allocation of epidermal area when plants evolve towards higher gsmax . Our results specifically highlight that the stomatal morphology of angiosperms evolved along spatially optimal allometric relationships. We propose that the resulting wide range of viable stomatal trait combinations equips angiosperms with developmental and evolutionary flexibility in leaf gas exchange unrivalled by gymnosperms and pteridophytes. © 2016 The Authors New Phytologist © 2016 New Phytologist Trust.

Cyberbullying: A Review of the Legal Issues Facing Educators

ERIC Educational Resources Information Center

Hinduja, Sameer; Patchin, Justin W.

2011-01-01

School districts are often given the challenging task of addressing problematic online behaviors committed by students while simultaneously protecting themselves from civil liability by not overstepping their authority. This is difficult, because the law concerning these behaviors is ambiguous and continuously evolving, and little consensus has…

Programming Success for the Disadvantaged Learner

ERIC Educational Resources Information Center

Berman, Mark Laurence

1969-01-01

Describes a five year research project, undertaken by the U.S. Army at Guadalupe, Arizona, which used operant conditioning procedures in community development activities. The project sought "to determine environmental variables affecting individual and group behavior and, once these variables were identified, "to evolve a behavioral repertoire in…

Trends in "JPBI" Publications, 1999-2016

ERIC Educational Resources Information Center

Clarke, Shelley; Zakszeski, Brittany N.; Kern, Lee

2018-01-01

The field of positive behavior support (PBS) has expanded and evolved significantly since the first issue of "Journal of Positive Behavior Interventions" ("JPBI") was published. To ascertain how evolution of the field was reflected in the research, we examined trends in empirical studies published in "JPBI" since its…

Determining Gram-Equivalent Mass by Evolution of Hydrogen: An Improved Experiment.

ERIC Educational Resources Information Center

Hopper, Marlon E.

1993-01-01

Describes an experiment where the gram-equivalent mass of an unknown metal is determined by reacting the metal with dilute hydrochloric acid and collecting the evolved gas over water. This simple, reliable experiment routinely gives results within 1% of the accepted value. (PR)

Predicting Residential Exposure to Phthalate Plasticizer Emitted from Vinyl Flooring - A Mechanistic Analysis

EPA Science Inventory

A two-room model is developed to estimate the emission rate of di-2-ethylhexyl phthalate (DEHP) from vinyl flooring and the evolving gas-phase and adsorbed surface concentrations in a realistic indoor environment. Adsorption isotherms for phthalates and plasticizers on interior ...

IPCC Methodologies for the Waste Sector: Past, Present, and Future

USDA-ARS?s Scientific Manuscript database

The reporting of national greenhouse gas (GHG) emissions began more than a decade ago by the signatory countries of the United Nations Framework Convention on Climate Change (UNFCCC). National GHG inventories rely on the evolving Intergovernmental Panel on Climate Change (IPCC) national GHG inventor...

Shallowly driven fluctuations in lava lake outgassing (gas pistoning), Kīlauea Volcano

NASA Astrophysics Data System (ADS)

Patrick, Matthew R.; Orr, Tim; Sutton, A. J.; Lev, Einat; Thelen, Wes; Fee, David

2016-01-01

Lava lakes provide ideal venues for directly observing and understanding the nature of outgassing in basaltic magmatic systems. Kīlauea Volcano's summit lava lake has persisted for several years, during which seismic and infrasonic tremor amplitudes have exhibited episodic behavior associated with a rise and fall of the lava surface (;gas pistoning;). Since 2010, the outgassing regime of the lake has been tied to the presence or absence of gas pistoning. During normal behavior (no gas pistoning), the lake is in a ;spattering; regime, consisting of higher tremor amplitudes and gas emissions. In comparison, gas piston events are associated with an abrupt rise in lava level (up to 20 m), during which the lake enters a ;non-spattering; regime with greatly decreased tremor and gas emissions. We study this episodic behavior using long-term multidisciplinary monitoring of the lake, including seismicity, infrasound, gas emission and geochemistry, and time-lapse camera observations. The non-spattering regime (i.e. rise phase of a gas piston cycle) reflects gas bubbles accumulating near the top of the lake, perhaps as a shallow foam, while spattering regimes represent more efficient decoupling of gas from the lake. We speculate that the gas pistoning might be controlled by time-varying porosity and/or permeability in the upper portions of the lava lake, which may modulate foam formation and collapse. Competing models for gas pistoning, such as deeply sourced gas slugs, or dynamic pressure balances, are not consistent with our observations. Unlike other lava lakes which have cyclic behavior that is thought to be controlled by deeply sourced processes, external to the lake itself, we show an example of lava lake fluctuations driven by cycles of activity at shallow depth and close to the lake's surface. These observations highlight the complex and unsteady nature of outgassing from basaltic magmatic systems.

Inhibited phase behavior of gas hydrates in graphene oxide: influences of surface and geometric constraints.

PubMed

Kim, Daeok; Kim, Dae Woo; Lim, Hyung-Kyu; Jeon, Jiwon; Kim, Hyungjun; Jung, Hee-Tae; Lee, Huen

2014-11-07

Porous materials have provided us unprecedented opportunities to develop emerging technologies such as molecular storage systems and separation mechanisms. Pores have also been used as supports to contain gas hydrates for the application in gas treatments. Necessarily, an exact understanding of the properties of gas hydrates in confining pores is important. Here, we investigated the formation of CO2, CH4 and N2 hydrates in non-interlamellar voids in graphene oxide (GO), and their thermodynamic behaviors. For that, low temperature XRD and P-T traces were conducted to analyze the water structure and confirm hydrate formation, respectively, in GO after its exposure to gaseous molecules. Confinement and strong interaction of water with the hydrophilic surface of graphene oxide reduce water activity, which leads to the inhibited phase behavior of gas hydrates.

Unique Footprint in the scl1.3 Locus Affects Adhesion and Biofilm Formation of the Invasive M3-Type Group A Streptococcus.

PubMed

Bachert, Beth A; Choi, Soo J; LaSala, Paul R; Harper, Tiffany I; McNitt, Dudley H; Boehm, Dylan T; Caswell, Clayton C; Ciborowski, Pawel; Keene, Douglas R; Flores, Anthony R; Musser, James M; Squeglia, Flavia; Marasco, Daniela; Berisio, Rita; Lukomski, Slawomir

2016-01-01

The streptococcal collagen-like proteins 1 and 2 (Scl1 and Scl2) are major surface adhesins that are ubiquitous among group A Streptococcus (GAS). Invasive M3-type strains, however, have evolved two unique conserved features in the scl1 locus: (i) an IS1548 element insertion in the scl1 promoter region and (ii) a nonsense mutation within the scl1 coding sequence. The scl1 transcript is drastically reduced in M3-type GAS, contrasting with a high transcription level of scl1 allele in invasive M1-type GAS. This leads to a lack of Scl1 expression in M3 strains. In contrast, while scl2 transcription and Scl2 production are elevated in M3 strains, M1 GAS lack Scl2 surface expression. M3-type strains were shown to have reduced biofilm formation on inanimate surfaces coated with cellular fibronectin and laminin, and in human skin equivalents. Repair of the nonsense mutation and restoration of Scl1 expression on M3-GAS cells, restores biofilm formation on cellular fibronectin and laminin coatings. Inactivation of scl1 in biofilm-capable M28 and M41 strains results in larger skin lesions in a mouse model, indicating that lack of Scl1 adhesin promotes bacterial spread over localized infection. These studies suggest the uniquely evolved scl1 locus in the M3-type strains, which prevents surface expression of the major Scl1 adhesin, contributed to the emergence of the invasive M3-type strains. Furthermore these studies provide insight into the molecular mechanisms mediating colonization, biofilm formation, and pathogenesis of group A streptococci.

STAR FORMATION ACTIVITY IN THE GALACTIC H II COMPLEX S255-S257

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ojha, D. K.; Ghosh, S. K.; Samal, M. R.

We present results on the star formation activity of an optically obscured region containing an embedded cluster (S255-IR) and molecular gas between two evolved H II regions, S255 and S257. We have studied the complex using optical and near-infrared (NIR) imaging, optical spectroscopy, and radio continuum mapping at 15 GHz, along with Spitzer-IRAC results. We found that the main exciting sources of the evolved H II regions S255 and S257 and the compact H II regions associated with S255-IR are of O9.5-B3 V nature, consistent with previous observations. Our NIR observations reveal 109 likely young stellar object (YSO) candidates inmore » an area of {approx}4.'9 x 4.'9 centered on S255-IR, which include 69 new YSO candidates. To see the global star formation, we constructed the V - I/V diagram for 51 optically identified IRAC YSOs in an area of {approx}13' x 13' centered on S255-IR. We suggest that these YSOs have an approximate age between 0.1 and 4 Myr, indicating a non-coeval star formation. Using spectral energy distribution models, we constrained physical properties and evolutionary status of 31 and 16 YSO candidates outside and inside the gas ridge, respectively. The models suggest that the sources associated with the gas ridge are younger (mean age {approx}1.2 Myr) than the sources outside the gas ridge (mean age {approx}2.5 Myr). The positions of the young sources inside the gas ridge at the interface of the H II regions S255 and S257 favor a site of induced star formation.« less

Sulfur-Bearing Phases Detected by Evolved Gas Analysis of the Rocknest Aeolian Deposit, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Mcadam, Amy Catherine; Franz, Heather Bryant

2014-01-01

The Sample Analysis at Mars (SAM) instrument suite detected SO2, H2S, OCS, and CS2 from approx.450 to 800 C during evolved gas analysis (EGA) of materials from the Rocknest aeolian deposit in Gale Crater, Mars. This was the first detection of evolved sulfur species from a Martian surface sample during in situ EGA. SO2(approx. 3-22 micro-mol) is consistent with the thermal decomposition of Fe sulfates or Ca sulfites, or evolution/desorption from sulfur-bearing amorphous phases. Reactions between reduced sulfur phases such as sulfides and evolved O2 or H2O in the SAM oven are another candidate SO2 source. H2S (approx.41-109 nmol) is consistent with interactions of H2O, H2 and/or HCl with reduced sulfur phases and/or SO2 in the SAM oven. OCS (approx.1-5 nmol) and CS2(approx.0.2-1 nmol) are likely derived from reactions between carbon-bearing compounds and reduced sulfur. Sulfates and sulfites indicate some aqueous interactions, although not necessarily at the Rocknest site; Fe sulfates imply interaction with acid solutions whereas Ca sulfites can form from acidic to near-neutral solutions. Sulfides in the Rocknest materials suggest input from materials originally deposited in a reducing environment or from detrital sulfides from an igneous source. The presence of sulfides also suggests that the materials have not been extensively altered by oxidative aqueous weathering. The possibility of both reduced and oxidized sulfur compounds in the deposit indicates a nonequilibrium assemblage. Understanding the sulfur mineralogy in Rocknest materials, which exhibit chemical similarities to basaltic fines analyzed elsewhere on Mars, can provide insight in to the origin and alteration history of Martian surface materials.

Mate-choice copying: A fitness-enhancing behavior that evolves by indirect selection.

PubMed

Santos, Mauro; Sapage, Manuel; Matos, Margarida; Varela, Susana A M

2017-06-01

A spatially explicit, individual-based simulation model is used to study the spread of an allele for mate-choice copying (MCC) through horizontal cultural transmission when female innate preferences do or do not coevolve with a male viability-increasing trait. Evolution of MCC is unlikely when innate female preferences coevolve with the trait, as copier females cannot express a higher preference than noncopier females for high-fitness males. However, if a genetic polymorphism for innate preference persists in the population, MCC can evolve by indirect selection through hitchhiking: the copying allele hitchhikes on the male trait. MCC can be an adaptive behavior-that is, a behavior that increases a population's average fitness relative to populations without MCC-even though the copying allele itself may be neutral or mildly deleterious. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Coding principles of the canonical cortical microcircuit in the avian brain

PubMed Central

Calabrese, Ana; Woolley, Sarah M. N.

2015-01-01

Mammalian neocortex is characterized by a layered architecture and a common or “canonical” microcircuit governing information flow among layers. This microcircuit is thought to underlie the computations required for complex behavior. Despite the absence of a six-layered cortex, birds are capable of complex cognition and behavior. In addition, the avian auditory pallium is composed of adjacent information-processing regions with genetically identified neuron types and projections among regions comparable with those found in the neocortex. Here, we show that the avian auditory pallium exhibits the same information-processing principles that define the canonical cortical microcircuit, long thought to have evolved only in mammals. These results suggest that the canonical cortical microcircuit evolved in a common ancestor of mammals and birds and provide a physiological explanation for the evolution of neural processes that give rise to complex behavior in the absence of cortical lamination. PMID:25691736

Why are there apes? Evidence for the co-evolution of ape and monkey ecomorphology.

PubMed

Hunt, Kevin D

2016-04-01

Apes, members of the superfamily Hominoidea, possess a distinctive suite of anatomical and behavioral characters which appear to have evolved relatively late and relatively independently. The timing of paleontological events, extant cercopithecine and hominoid ecomorphology and other evidence suggests that many distinctive ape features evolved to facilitate harvesting ripe fruits among compliant terminal branches in tree edges. Precarious, unpredictably oriented, compliant supports in the canopy periphery require apes to maneuver using suspensory and non-sterotypical postures (i.e. postures with eccentric limb orientations or extreme joint excursions). Diet differences among extant species, extant species numbers and evidence of cercopithecoid diversification and expansion, in concert with a reciprocal decrease in hominoid species, suggest intense competition between monkeys and apes over the last 20 Ma. It may be that larger body masses allow great apes to succeed in contest competitions for highly desired food items, while the ability of monkeys to digest antifeedant-rich unripe fruits allows them to win scramble competitions. Evolutionary trends in morphology and inferred ecology suggest that as monkeys evolved to harvest fruit ever earlier in the fruiting cycle they broadened their niche to encompass first more fibrous, tannin- and toxin-rich unripe fruits and later, for some lineages, mature leaves. Early depletion of unripe fruit in the central core of the tree canopy by monkeys leaves a hollow sphere of ripening fruits, displacing antifeedant-intolerant, later-arriving apes to small-diameter, compliant terminal branches. Hylobatids, orangutans, Pan species, gorillas and the New World atelines may have each evolved suspensory behavior independently in response to local competition from an expanding population of monkeys. Genetic evidence of rapid evolution among chimpanzees suggests that adaptations to suspensory behavior, vertical climbing, knuckle-walking, consumption of terrestrial piths and intercommunity violence had not yet evolved or were still being refined when panins (chimpanzees and bonobos) and hominins diverged. © 2016 Anatomical Society.

Bio-conversion of water hyacinths into methane gas. Part 1. [Effects of cadmium and nickel pollution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolverton, B.C.; Mcdonald, R.C.; Gordon, J.

1974-07-01

Bio-gas and methane production from the microbial anaerobic decomposition of water hyacinths (Eichhornia crassipes) (Mart) Solms was investigated. These experiments demonstrated the ability of water hyacinths to produce an average of 13.9 ml of methane gas per gram of wet plant weight. This study revealed that sample preparation had no significant effect on bio-gas and/or methane production. Pollution of water hyacinths by two toxic heavy materials, nickel and cadmium, increased the rate of methane production from 51.8 ml/day for non-contaminated plants incubated at 36 C to 81.0 ml/day for Ni-Cd contaminated plants incubated at the same temperature. The methane contentmore » of bio-gas evolved from the anaerobic decomposition of Ni-Cd contaminated plants was 91.1 percent as compared to 69.2 percent methane content of bio-gas collected from the fermentation of non-contaminated plants. (Author) (GRA)« less

How simple autonomous decisions evolve into robust behaviours? A review from neurorobotics, cognitive, self-organized and artificial immune systems fields.

PubMed

Fernandez-Leon, Jose A; Acosta, Gerardo G; Rozenfeld, Alejandro

2014-10-01

Researchers in diverse fields, such as in neuroscience, systems biology and autonomous robotics, have been intrigued by the origin and mechanisms for biological robustness. Darwinian evolution, in general, has suggested that adaptive mechanisms as a way of reaching robustness, could evolve by natural selection acting successively on numerous heritable variations. However, is this understanding enough for realizing how biological systems remain robust during their interactions with the surroundings? Here, we describe selected studies of bio-inspired systems that show behavioral robustness. From neurorobotics, cognitive, self-organizing and artificial immune system perspectives, our discussions focus mainly on how robust behaviors evolve or emerge in these systems, having the capacity of interacting with their surroundings. These descriptions are twofold. Initially, we introduce examples from autonomous robotics to illustrate how the process of designing robust control can be idealized in complex environments for autonomous navigation in terrain and underwater vehicles. We also include descriptions of bio-inspired self-organizing systems. Then, we introduce other studies that contextualize experimental evolution with simulated organisms and physical robots to exemplify how the process of natural selection can lead to the evolution of robustness by means of adaptive behaviors. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Replacing Coercive Power with Relationship Power

ERIC Educational Resources Information Center

Boldt, Randal W.; Witzel, Melanie; Russell, Chuck; Jones, Van

2007-01-01

A long-established agency for troubled children was following a philosophy based on behavioral control and treatment of pathology. As staff examined their beliefs about the process of change, the climate evolved from enforcing behavior control to empowering youth to develop positive strengths. A charter school was created and new behavior…

The Relationship of Nutrition to Brain Development and Behavior.

ERIC Educational Resources Information Center

National Academy of Sciences - National Research Council, Washington, DC. Committee on International Nutrition Programs.

The physical, chemical, and physiological development of the brain and consequent behavior in all species of higher animals evolves from the continuous interaction of genetic and numerous environmental factors. Among the latter are nutritional, disease, psychological, learning, and cultural variables. Of these, nutrition is concerned directly with…

Bubble behavior characteristics based on virtual binocular stereo vision

NASA Astrophysics Data System (ADS)

Xue, Ting; Xu, Ling-shuang; Zhang, Shang-zhen

2018-01-01

The three-dimensional (3D) behavior characteristics of bubble rising in gas-liquid two-phase flow are of great importance to study bubbly flow mechanism and guide engineering practice. Based on the dual-perspective imaging of virtual binocular stereo vision, the 3D behavior characteristics of bubbles in gas-liquid two-phase flow are studied in detail, which effectively increases the projection information of bubbles to acquire more accurate behavior features. In this paper, the variations of bubble equivalent diameter, volume, velocity and trajectory in the rising process are estimated, and the factors affecting bubble behavior characteristics are analyzed. It is shown that the method is real-time and valid, the equivalent diameter of the rising bubble in the stagnant water is periodically changed, and the crests and troughs in the equivalent diameter curve appear alternately. The bubble behavior characteristics as well as the spiral amplitude are affected by the orifice diameter and the gas volume flow.

X-radiation from clusters of galaxies: Spectral evidence for a hot evolved gas

NASA Technical Reports Server (NTRS)

Serlemitsos, P. J.; Smith, B. W.; Boldt, E. A.; Holt, S. S.; Swank, J. H.

1976-01-01

OSO-8 observations of the X-ray flux in the range 2-60 keV from the Virgo, Perseus, and Coma Clusters provide strong evidence for the thermal origin of the radiation, including iron line emission. The data are adequately described by emission from an isothermal plasma with an iron abundance in near agreement with cosmic levels. A power law description is generally less acceptable and is ruled out in the case of Perseus. Implications on the origin of the cluster gas are discussed.

Portable chemical detection system with intergrated preconcentrator

DOEpatents

Baumann, Mark J.; Brusseau, Charles A.; Hannum, David W.; Linker, Kevin L.

2005-12-27

A portable system for the detection of chemical particles such as explosive residue utilizes a metal fiber substrate that may either be swiped over a subject or placed in a holder in a collection module which can shoot a jet of gas at the subject to dislodge residue, and then draw the air containing the residue into the substrate. The holder is then placed in a detection module, which resistively heats the substrate to evolve the particles, and provides a gas flow to move the particles to a miniature detector in the module.

Dual porosity gas evolving electrode

DOEpatents

Townsend, C.W.

1994-11-15

A dual porosity electrode is described for use in thermoelectrochemical systems where simultaneous transport of gas and liquid into and/or out of the electrode is required. The electrode includes catalytic electrode particles having diameters ranging from about 25 to 100 angstroms. The catalytic electrode particles are anchored to a support network in clusters which have internal pores ranging in size from 25 to 100 angstroms. The pores between the clusters range in size from between about 1 to 20 microns. A method for making the dual porosity electrodes is also disclosed.

More on duel purpose solar-electric power plants

NASA Astrophysics Data System (ADS)

Hall, F. F.

Rationale for such plants is reviewed and plant elements are listed. Dual purpose solar-electric plants would generate both electricity and hydrogen gas for conversion to ammonia or methanol or direct use as a fuel of unsurpassed specific power and cleanliness. By-product oxygen would also be sold to owners of hydrogen age equipment. Evolved gasses at high pressure could be fired in compressorless gas turbines, boilerless steam-turbines or fuel-cell-inverter hydrogen-electric power drives of high thermal efficiency as well as in conventional internal combustion engines.

Method of preparing pure fluorine gas

DOEpatents

Asprey, Larned B.

1976-01-01

A simple, inexpensive system for purifying and storing pure fluorine is described. The method utilizes alkali metal-nickel fluorides to absorb tank fluorine by forming nickel complex salts and leaving the gaseous impurities which are pumped away. The complex nickel fluoride is then heated to evolve back pure gaseous fluorine.

Remote control flare stack igniter for combustible gases

NASA Technical Reports Server (NTRS)

Ray, W. L.

1972-01-01

Device has been designed and developed for igniting nonrecoverable combustible gases and sustaining combustion of gases evolving from various gas vent stacks. Igniter is superior to existing systems because of simplicity of operation, low cost fabrication, installation, operational and maintainability features, and excellent reliability in all phases of required operations.

A Mass Spectrometer Simulator in Your Computer

ERIC Educational Resources Information Center

Gagnon, Michel

2012-01-01

Introduced to study components of ionized gas, the mass spectrometer has evolved into a highly accurate device now used in many undergraduate and research laboratories. Unfortunately, despite their importance in the formation of future scientists, mass spectrometers remain beyond the financial reach of many high schools and colleges. As a result,…

Is Superhydrophobicity Equal to Underwater Superaerophilicity: Regulating the Gas Behavior on Superaerophilic Surface via Hydrophilic Defects.

PubMed

Cao, Moyuan; Li, Zhe; Ma, Hongyu; Geng, Hui; Yu, Cunming; Jiang, Lei

2018-06-20

Superhydrophobic surfaces have long been considered as superaerophilic surfaces while being placed in the aqueous environment. However, versatile gas/solid interacting phenomena were reported by utilizing different superhydrophobic substrates, indicating that these two wetting states cannot be simply equated. Herein, we demonstrate how the hydrophilic defects on the superhydrophobic track manipulate the underwater gas delivery, without deteriorating the water repellency of the surface in air. The versatile gas-transporting processes can be achieved on the defected superhydrophobic surfaces; on the contrary, in air, a water droplet is able to roll on those surfaces indistinguishably. Results show that the different media pressures applied on the two wetting states determine the diversified fluid-delivering phenomena; that is, the pressure-induced hydrophilic defects act as a gas barrier to regulate the bubble motion behavior under water. Through the rational incorporation of hydrophilic defects, a series of gas-transporting behaviors are achieved purposively, for example, gas film delivery, bubble transporting, and anisotropic bubble gating, which proves the feasibility of this underwater air-controlling strategy.

Dual Source Time-of-flight Mass Spectrometer and Sample Handling System

NASA Astrophysics Data System (ADS)

Brinckerhoff, W.; Mahaffy, P.; Cornish, T.; Cheng, A.; Gorevan, S.; Niemann, H.; Harpold, D.; Rafeek, S.; Yucht, D.

We present details of an instrument under development for potential NASA missions to planets and small bodies. The instrument comprises a dual ionization source (laser and electron impact) time-of-flight mass spectrometer (TOF-MS) and a carousel sam- ple handling system for in situ analysis of solid materials acquired by, e.g., a coring drill. This DSTOF instrument could be deployed on a fixed lander or a rover, and has an open design that would accommodate measurements by additional instruments. The sample handling system (SHS) is based on a multi-well carousel, originally de- signed for Champollion/DS4. Solid samples, in the form of drill cores or as loose chips or fines, are inserted through an access port, sealed in vacuum, and transported around the carousel to a pyrolysis cell and/or directly to the TOF-MS inlet. Samples at the TOF-MS inlet are xy-addressable for laser or optical microprobe. Cups may be ejected from their holders for analyzing multiple samples or caching them for return. Samples are analyzed with laser desorption and evolved-gas/electron-impact sources. The dual ion source permits studies of elemental, isotopic, and molecular composition of unprepared samples with a single mass spectrometer. Pulsed laser desorption per- mits the measurement of abundance and isotope ratios of refractory elements, as well as the detection of high-mass organic molecules in solid samples. Evolved gas analysis permits similar measurements of the more volatile species in solids and aerosols. The TOF-MS is based on previous miniature prototypes at JHU/APL that feature high sensitivity and a wide mass range. The laser mode, in which the sample cup is directly below the TOF-MS inlet, permits both ablation and desorption measurements, to cover elemental and molecular species, respectively. In the evolved gas mode, sample cups are raised into a small pyrolysis cell and heated, producing a neutral gas that is elec- tron ionized and pulsed into the TOF-MS. (Any imaging and laser microprobe studies would necessarily precede the pyrolysis step to assure that the grain-scale composition is captured.)

Implications of Abundant Gas and Oil for Climate Forcing

NASA Astrophysics Data System (ADS)

Edmonds, J.

2015-12-01

Perhaps the most important development in the field of energy over the past decade has been the advent of technologies that enable the production of larger volumes of natural gas and oil at lower cost. The availability of more abundant gas and oil is reshaping the global energy system, with implications for both evolving emissions of CO2 and other climate forcers. More abundant gas and oil will also transform the character of greenhouse gas emissions mitigation. We review recent findings regarding the impact of abundant gas and oil for climate forcing and the challenge of emissions mitigation. We find strong evidence that, absent policies to limits its penetration against renewable energy, abundant gas has little observable impact on CO2 emissions, and tends to increase overall climate forcing, though the latter finding is subject to substantial uncertainty. The presence of abundant gas also affects emissions mitigation. There is relatively little literature exploring the implication of expanded gas availability on the difficulty in meeting emissions mitigation goals. However, preliminary results indicate that on global scales abundant gas does not substantially affect the cost of emissions mitigation, even though natural gas could have an expanded role in emissions mitigation scenarios as compared with scenarios in which natural gas is less abundant.

Antibiotic Treatment Attenuates Behavioral and Neurochemical Changes Induced by Exposure of Rats to Group A Streptococcal Antigen

PubMed Central

Lotan, Dafna; Cunningham, Madeleine; Joel, Daphna

2014-01-01

Post-streptococcal A (GAS) sequelae including movement and neuropsychiatric disorders have been associated with improvement in response to antibiotic therapy. Besides eradication of infection, the underlying basis of attenuation of neuropsychiatric symptoms following antibiotic treatment is not known. The aim of the present study was to test the efficacy of antibiotic treatment in a rat model of GAS-related neuropsychiatric disorders. In the model, rats were not infected but were exposed to GAS-antigen or to adjuvants only (Control rats) and treated continuously with the antibiotic ampicillin in their drinking water from the first day of GAS-antigen exposure. Two additional groups of rats (GAS and Control) did not receive ampicillin in their drinking water. Behavior of the four groups was assessed in the forced swim, marble burying and food manipulation assays. We assessed levels of D1 and D2 dopamine receptors and tyrosine hydroxylase in the prefrontal cortex and striatum, and IgG deposition in the prefrontal cortex, striatum and thalamus. Ampicillin treatment prevented emergence of the motor and some of the behavioral alterations induced by GAS-antigen exposure, reduced IgG deposition in the thalamus of GAS-exposed rats, and tended to attenuate the increase in the level of TH and D1 and D2 receptors in their striatum, without concomitantly reducing the level of sera anti-GAS antibodies. Our results reinforce the link between exposure to GAS antigen, dysfunction of central dopaminergic pathways and motor and behavioral alterations. Our data further show that some of these deleterious effects can be attenuated by antibiotic treatment, and supports the latter’s possible efficacy as a prophylactic treatment in GAS-related neuropsychiatric disorders. PMID:24979049

Corrosion Issues for Ceramics in Gas Turbines

NASA Technical Reports Server (NTRS)

Jacobson, Nathan; Opila, Elizabeth; Nickel, Klaus G.

2004-01-01

The requirements for hot-gas-path materials in gas turbine engines are demanding. These materials must maintain high strength and creep resistance in a particularly aggressive environment. A typical gas turbine environment involves high temperatures, rapid gas flow rates, high pressures, and a complex mixture of aggressive gases. Over the past forty years, a wealth of information on the behavior of ceramic materials in heat engine environments has been obtained. In the first part of the talk we summarize the behavior of monolithic SiC and Si3N4. These materials show excellent baseline behavior in clean, oxygen environments. However the aggressive components in a heat engine environment such as water vapor and salt deposits can be quite degrading. In the second part of the talk we discuss SiC-based composites. The critical issue with these materials is oxidation of the fiber coating. We conclude with a brief discussion of future directions in ceramic corrosion research.

Relative Effects of Daily Feedback and Weekly Feedback on Customer Service Behavior at a Gas Station

ERIC Educational Resources Information Center

So, Yongjoon; Lee, Kyehoon; Oah, Shezeen

2013-01-01

The relative effects of daily and weekly feedback on customer service behavior at a gas station were assessed using an ABC within-subjects design. Four critical service behaviors were identified and measured daily. After baseline (A), weekly feedback (B) was introduced, and daily feedback (C) was introduced in the next phase. The results indicated…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.V.

This book reports on remedial measures for gas wells and new methods for calculating the position of the stabilized performance curves for gas wells as well as the heating value for natural gases from compositional analyses. In addition, the author includes problem solutions in an appendix and a section showing the relation between the conventional empirical equation and the theoretical performance equation of A.S. Odeh. The author successfully bridges the gap between the results of empirical testing and the theory of unsteady-state flow in porous media. It strengthens the bond between conventional reservoir engineering practices and understanding gas well behavior.more » Problems listed at the end of each chapter are excellent exercises for practitioners. This book provides information on: Natural Gas Engineering; Properties of natural gas; Application of gas laws to reservoir engineering; Gas measurement; Flow of natural gas in circular pipe and annular conductors; Flow of gas in porous media (a review); Gas well testing; Unsteady-state flow behavior of gas wells; Production forecasting for gas wells; Production decline curves for gas wells; Sizing flow strings for gas wells; Remedial measures for gas wells; Gas sales contracts; and appendices on Compressibility for natural gas, Gas measurement factors, SI metric conversion factors, and Solutions to problems.« less

Evolving neural networks through augmenting topologies.

PubMed

Stanley, Kenneth O; Miikkulainen, Risto

2002-01-01

An important question in neuroevolution is how to gain an advantage from evolving neural network topologies along with weights. We present a method, NeuroEvolution of Augmenting Topologies (NEAT), which outperforms the best fixed-topology method on a challenging benchmark reinforcement learning task. We claim that the increased efficiency is due to (1) employing a principled method of crossover of different topologies, (2) protecting structural innovation using speciation, and (3) incrementally growing from minimal structure. We test this claim through a series of ablation studies that demonstrate that each component is necessary to the system as a whole and to each other. What results is significantly faster learning. NEAT is also an important contribution to GAs because it shows how it is possible for evolution to both optimize and complexify solutions simultaneously, offering the possibility of evolving increasingly complex solutions over generations, and strengthening the analogy with biological evolution.

A study of volatile organic compounds evolved from the decaying human body.

PubMed

Statheropoulos, M; Spiliopoulou, C; Agapiou, A

2005-10-29

Two men were found dead near the island of Samos, Greece, in the Mediterranean sea. The estimated time of death for both victims was 3-4 weeks. Autopsy revealed no remarkable external injuries or acute poisoning. The exact cause of death remained unclear because the bodies had advanced decomposition. Volatile organic compounds (VOCs) evolved from these two corpses were determined by thermal desorption/gas chromatography/mass spectrometry analysis (TD/GC/MS). Over 80 substances have been identified and quantified. The most prominent among them were dimethyl disulfide (13.39 nmol/L), toluene (10.11 nmol/L), hexane (5.58 nmol/L), benzene 1,2,4-trimethyl (4.04 nmol/L), 2-propanone (3.84 nmol/L), 3-pentanone (3.59 nmol/L). Qualitative and quantitative differences among the evolved VOCs and CO2 mean concentration values might indicate different rates of decomposition between the two bodies. The study of the evolved VOCs appears to be a promising adjunct to the forensic pathologist as they may offer important information which can be used in his final evaluation.

The Experimental Study of Dynamics of Scaled Gas-Filled Bubble Collapse in Liquid

NASA Astrophysics Data System (ADS)

Pavlenko, Alexander

2011-06-01

The article provides results of analyzing special features of the single-bubble sonoluminescence, developing the special apparatus to investigate this phenomenon on a larger-scale basis. Certain very important effects of high energy density physics, i.e. liquid compressibility, shock-wave formation under the collapse of the gas cavity in liquid, shock-wave focusing in the gas-filled cavity, occurrence of hot dense plasma in the focusing area, and high-temperature radiation yield are observed in this phenomenon. Specificity of the process is conditioned by the ``ideal'' preparation and sphericity of the gas-and-liquid contact boundary what makes the collapse process efficient due to the reduced influence of hydrodynamic instabilities. Results of experimental investigations; results of developing the facilities, description of methods used to register parameters of facilities and the system under consideration; analytical estimates how gas-filled bubbles evolve in liquid with the regard for scale effects; results of preliminary 1-D gas dynamic calculations of the gas bubble evolution are presented. The work supported by ISTC Project #2116.

Time-dependent deformation of gas shales - role of rock framework versus reservoir fluids

NASA Astrophysics Data System (ADS)

Hol, Sander; Zoback, Mark

2013-04-01

Hydraulic fracturing operations are generally performed to achieve a fast, drastic increase of permeability and production rates. Although modeling of the underlying short-term mechanical response has proven successful via conventional geomechanical approaches, predicting long-term behavior is still challenging as the formation interacts physically and chemically with the fluids present in-situ. Recent experimental work has shown that shale samples subjected to a change in effective stress deform in a time-dependent manner ("creep"). Although the magnitude and nature of this behavior is strongly related to the composition and texture of the sample, also the choice of fluid used in the experiments affects the total strain response - strongly adsorbing fluids result in more, recoverable creep. The processes underlying time-dependent deformation of shales under in-situ stresses, and the long-term impact on reservoir performance, are at present poorly understood. In this contribution, we report triaxial mechanical tests, and theoretical/thermodynamic modeling work with the aim to identify and describe the main mechanisms that control time-dependent deformation of gas shales. In particular, we focus on the role of the shale solid framework versus the type and pressure of the present pore fluid. Our experiments were mainly performed on Eagle Ford Shale samples. The samples were subjected to cycles of loading and unloading, first in the dry state, and then again after equilibrating them with (adsorbing) CO2 and (non-adsorbing) He at fluid pressures of 4 MPa. Stresses were chosen close to those persisting under in-situ conditions. The results of our tests demonstrate that likely two main types of deformation mechanisms operate that relate to a) the presence of microfractures as a dominating feature in the solid framework of the shale, and b) the adsorbing potential of fluids present in the nanoscale voids of the shale. To explain the role of adsorption in the observed compaction creep, we postulate a serial coupling between 1) stress-driven desorption of the fluid species, 2) diffusion of the desorbed species out of the solid, and 3) consequent shrinkage. We propose a model in which the total shrinkage of the solid (Step 3) that is measured as bulk compaction, is driven by a change in stress state (Step 1), and evolves in time controlled by the diffusion characteristics of the system (Step 2). Our experimental and modeling study shows that both the nature of the solid framework of the shale, as well as the type and pressure of pore fluids affect the long-term in-situ mechanical behavior of gas shale reservoirs.

A Three Decade Evolution to Transdisciplinary Research: Community Health Research in California-Mexico Border Communities

PubMed Central

Elder, John P.; Ayala, Guadalupe X.; McKenzie, Thomas L.; Litrownik, Alan J.; Gallo, Linda C.; Arredondo, Elva M.; Talavera, Gregory A.; Kaplan, Robert M.

2013-01-01

Background The Institute for Behavioral and Community Health (IBACH) is a transdisciplinary organization with a team-oriented approach to the translation of research to practice and policy within the context of behavioral medicine. Objectives This paper tracks the growth of IBACH — in the context of evolving multi-university transdisciplinary research efforts — from a behavioral medicine research focus to community approaches to disease prevention and control, ultimately specializing in Latino health research and practice. We describe how this growth was informed by our partnerships with community members and organizations, and training a diverse array of students and young professionals. Methods Since 1982, IBACH’s research has evolved to address a greater breadth of factors associated with health and well-being. This was driven by our strong community focus and emphasis on collaborations, the diversity of our investigative teams, and our emphasis on training. Although behavioral science still forms the core of IBACH’s scientific orientation, research efforts extend beyond those traditionally examined. Conclusions IBACH’s “team science” successes have been fueled by a specific population emphasis making IBACH one of the nation’s leaders in Latino health behavior research. PMID:25435566

The evolution of reputation-based partner-switching behaviors with a cost

PubMed Central

Li, Yixiao

2014-01-01

Humans constantly adjust their social relationships and choose new partners of good reputations, thereby promoting the evolution of cooperation. Individuals have to pay a cost to build a reputation, obtain others' information and then make partnership adjustments, yet the conditions under which such costly behaviors are able to evolve remain to be explored. In this model, I assume that individuals have to pay a cost to adjust their partnerships. Furthermore, whether an individual can adjust his partnership based on reputation is determined by his strategic preference, which is updated via coevolution. Using the metaphor of a public goods game where the collective benefit is shared among all members of a group, the coupling dynamics of cooperation and partnership adjustment were numerically simulated. Partner-switching behavior cannot evolve in a public goods game with a low amplification factor. However, such an effect can be exempted by raising the productivity of public goods or the frequency of partnership adjustment. Moreover, costly partner-switching behavior is remarkably promoted by the condition that the mechanism of reputation evaluation considers its prosociality. A mechanism of reputation evaluation that praises both cooperative and partner-switching behaviors allows them to coevolve. PMID:25091006

The evolution of reputation-based partner-switching behaviors with a cost

NASA Astrophysics Data System (ADS)

Li, Yixiao

2014-08-01

Humans constantly adjust their social relationships and choose new partners of good reputations, thereby promoting the evolution of cooperation. Individuals have to pay a cost to build a reputation, obtain others' information and then make partnership adjustments, yet the conditions under which such costly behaviors are able to evolve remain to be explored. In this model, I assume that individuals have to pay a cost to adjust their partnerships. Furthermore, whether an individual can adjust his partnership based on reputation is determined by his strategic preference, which is updated via coevolution. Using the metaphor of a public goods game where the collective benefit is shared among all members of a group, the coupling dynamics of cooperation and partnership adjustment were numerically simulated. Partner-switching behavior cannot evolve in a public goods game with a low amplification factor. However, such an effect can be exempted by raising the productivity of public goods or the frequency of partnership adjustment. Moreover, costly partner-switching behavior is remarkably promoted by the condition that the mechanism of reputation evaluation considers its prosociality. A mechanism of reputation evaluation that praises both cooperative and partner-switching behaviors allows them to coevolve.

Characterization of the Kinetics of NF3-Fluorination of NpO2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casella, Andrew M.; Scheele, Randall D.; McNamara, Bruce K.

2015-12-23

The exploitation of selected actinide and fission product fluoride volatilities has long been considered as a potentially attractive compact method for recycling used nuclear fuels to avoid generating the large volumes of radioactive waste arising from aqueous reprocessing [1-7]. The most developed process uses the aggressive and hazardous fluorinating agents hydrogen fluoride (HF) and/or molecular fluorine (F2) at high temperatures to volatilize the greatest fraction of the used nuclear fuel into a single gas stream. The volatilized fluorides are subsequently separated using a series of fractionation and condensation columns to recover the valuable fuel constituents and fission products. In pursuitmore » of a safer and less complicated approach, we investigated an alternative fluoride volatility-based process using the less hazardous fluorinating agent nitrogen trifluoride (NF3) and leveraging its less aggressive nature to selectively evolve fission product and actinide fluorides from the solid phase based on their reaction temperatures into a single recycle stream [8-15]. In this approach, successive isothermal treatments using NF3 will first evolve the more thermally susceptible used nuclear fuel constituents leaving the other constituents in the residual solids until subsequent isothermal temperature treatments cause these others to volatilize. During investigation of this process, individual neat used fuel components were treated with isothermal NF3 in an attempt to characterize the kinetics of each fluorination reaction to provide input into the design of a new volatile fluoride separations approach. In these directed investigations, complex behavior was observed between NF3 and certain solid reactants such as the actinide oxides of uranium, plutonium, and neptunium. Given the similar thermal reaction susceptibilities of neptunium oxide (NpO2) and uranium dioxide (UO2) and the importance of Np and U, we initially focused our efforts on determining the reaction kinetic parameters for NpO2. Characterizing the NF3 fluorination of NpO2 using established models for gas-solid reactions [16] proved unsuccessful so we developed a series of successive fundamental reaction mechanisms to characterize the observed successive fluorination reactions leading to production of the volatile neptunium hexafluoride (NpF6).« less

Paschen's law studies in cold gases

NASA Astrophysics Data System (ADS)

Massarczyk, R.; Chu, P.; Dugger, C.; Elliott, S. R.; Rielage, K.; Xu, W.

2017-06-01

The break-through voltage behavior over small gaps has been investigated for differing gap distances, gas pressures, and gas temperatures in nitrogen, neon, argon and xenon gases. A deviation from Paschen's law at micro gap distances has been found. At lower temperatures, a significant shift of the curve relative to the results at room temperature was observed. This behavior can be explained by combining Paschen's law and the ideal gas law.

Dietary hardness, loading behavior, and the evolution of skull form in bats.

PubMed

Santana, Sharlene E; Grosse, Ian R; Dumont, Elizabeth R

2012-08-01

The morphology and biomechanics of the vertebrate skull reflect the physical properties of diet and behaviors used in food acquisition and processing. We use phyllostomid bats, the most diverse mammalian dietary radiation, to investigate if and how changes in dietary hardness and loading behaviors during feeding shaped the evolution of skull morphology and biomechanics. When selective regimes of food hardness are modeled, we found that species consuming harder foods have evolved skull shapes that allow for more efficient bite force production. These species have shorter skulls and a greater reliance on the temporalis muscle, both of which contribute to a higher mechanical advantage at an intermediate gape angle. The evolution of cranial morphology and biomechanics also appears to be related to loading behaviors. Evolutionary changes in skull shape and the relative role of the temporalis and masseter in generating bite force are correlated with changes in the use of torsional and bending loading behaviors. Functional equivalence appears to have evolved independently among three lineages of species that feed on liquids and are not obviously morphologically similar. These trends in cranial morphology and biomechanics provide insights into behavioral and ecological factors shaping the skull of a trophically diverse clade of mammals. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Gas content and composition of gas hydrate from sediments of the southeastern North American continental margin

USGS Publications Warehouse

Lorenson, T.D.; Collett, T.S.

2000-01-01

Gas hydrate samples were recovered from four sites (Sites 994, 995, 996, and 997) along the crest of the Blake Ridge during Ocean Drilling Program (ODP) Leg 164. At Site 996, an area of active gas venting, pockmarks, and chemosynthetic communities, vein-like gas hydrate was recovered from less than 1 meter below seafloor (mbsf) and intermittently through the maximum cored depth of 63 mbsf. In contrast, massive gas hydrate, probably fault filling and/or stratigraphically controlled, was recovered from depths of 260 mbsf at Site 994, and from 331 mbsf at Site 997. Downhole-logging data, along with geochemical and core temperature profiles, indicate that gas hydrate at Sites 994, 995, and 997 occurs from about 180 to 450 mbsf and is dispersed in sediment as 5- to 30-m-thick zones of up to about 15% bulk volume gas hydrate. Selected gas hydrate samples were placed in a sealed chamber and allowed to dissociate. Evolved gas to water volumetric ratios measured on seven samples from Site 996 ranged from 20 to 143 mL gas/mL water to 154 mL gas/mL water in one sample from Site 994, and to 139 mL gas/mL water in one sample from Site 997, which can be compared to the theoretical maximum gas to water ratio of 216. These ratios are minimum gas/water ratios for gas hydrate because of partial dissociation during core recovery and potential contamination with pore waters. Nonetheless, the maximum measured volumetric ratio indicates that at least 71% of the cages in this gas hydrate were filled with gas molecules. When corrections for pore-water contamination are made, these volumetric ratios range from 29 to 204, suggesting that cages in some natural gas hydrate are nearly filled. Methane comprises the bulk of the evolved gas from all sites (98.4%-99.9% methane and 0%-1.5% CO2). Site 996 hydrate contained little CO2 (0%-0.56%). Ethane concentrations differed significantly from Site 996, where they ranged from 720 to 1010 parts per million by volume (ppmv), to Sites 994 and 997, which contained much less ethane (up to 86 ppmv). Up to 19 ppmv propane and other higher homologues were noted; however, these gases are likely contaminants derived from sediment in some hydrate samples. CO2 concentrations are less in gas hydrate than in the surrounding sediment, likely an artifact of core depressurization, which released CO2 derived from dissolved organic carbon (DIC) into sediment. The isotopic composition of methane from gas hydrate ranges from ??13C of -62.5??? to -70.7??? and ??D of -175??? to -200??? and is identical to the isotopic composition of methane from surrounding sediment. Methane of this isotopic composition is mainly microbial in origin and likely produced by bacterial reduction of bicarbonate. The hydrocarbon gases here are likely the products of early microbial diagenesis. The isotopic composition of CO2 from gas hydrate ranges from ??13C of -5.7 to -6.9, about 15??? lighter than CO2 derived from nearby sediment.

Brave new world revisited revisited: Huxley's evolving view of behaviorism

PubMed Central

Newman, Bobby

1992-01-01

Aldous Huxley's Brave New World has served as a popular and powerful source of antibehavioral sentiment. Several of Huxley's works are examined in order to ascertain his true thoughts regarding behaviorism. Early in his career Huxley failed to appreciate aspects of behavioral theory (e.g., an appreciation of heredity) or the good ends to which it could be employed. Huxley's later works portrayed behaviorism in a much more positive light, and he believed that behavioral science, along with spiritual enlightenment, might help save humanity from the Brave New World he predicted. PMID:22478115

Increases in Network Ties Are Associated with Increased Cohesion among Intervention Participants

ERIC Educational Resources Information Center

Gesell, Sabina B.; Barkin, Shari L.; Sommer, Evan C.; Thompson, Jessica R.; Valente, Thomas W.

2016-01-01

Objective: Many behavior change programs are delivered in group settings to manage implementation costs and to foster support and interactions among group members in order to facilitate behavior change. Understanding the group dynamics that evolve in group settings (e.g., weight management, Alcoholics Anonymous) is important, yet rarely measured.…

Evolving Science in Adolescence: Comment on Ellis et al. (2012)

ERIC Educational Resources Information Center

Dodge, Kenneth A.; Albert, Dustin

2012-01-01

Ellis et al. (2012) bring an evolutionary perspective to bear on adolescent risky behavioral development, clinical practice, and public policy. The authors offer important insights that (a) some risky behaviors may be adaptive for the individual and the species by being hard-wired due to fitness benefits and (b) interventions might be more…

Quenching versus quiescence: forming realistic massive ellipticals with a simple starvation model

NASA Astrophysics Data System (ADS)

Gutcke, Thales A.; Macciò, Andrea V.; Dutton, Aaron A.; Stinson, Greg S.

2017-04-01

The decrease in star formation (SF) and the morphological change necessary to produce the z = 0 elliptical galaxy population are commonly ascribed to a sudden quenching event, which is able to rid the central galaxy of its cold gas reservoir in a short time. Following this event, the galaxy is able to prevent further SF and stay quiescent via a maintenance mode. We test whether such a quenching event is truly necessary using a simple model of quiescence. In this model, hot gas (all gas above a temperature threshold) in an ˜1012 M⊙ halo mass galaxy at redshift z ˜ 3 is prevented from cooling. The cool gas continues to form stars at a decreasing rate and the galaxy stellar mass, morphology, velocity dispersion and position on the colour-magnitude diagram (CMD) proceed to evolve. By z = 0, the halo mass has grown to 1013 M⊙ and the galaxy has attained characteristics typical of an observed z = 0 elliptical galaxy. Our model is run in the framework of a cosmological, smooth particle hydrodynamic code that includes SF, early stellar feedback, supernova feedback, metal cooling and metal diffusion. Additionally, we post-process our simulations with a radiative transfer code to create a mock CMD. In contrast to previous assumptions that a pure 'fade away' model evolves too slowly to account for the sparsity of galaxies in the 'green valley', we demonstrate crossing times of ≲1 Gyr. We conclude that no sudden quenching event is necessary to produce such rapid colour transitions.

Characterizing the thermal distributions of warm molecular hydrogen in protoplanetary disks

NASA Astrophysics Data System (ADS)

Hoadley, Keri; France, Kevin

2016-01-01

Probing the surviving molecular gas within the inner regions of protoplanetary disks (PPDs) around T Tauri stars (1 - 10 Myr) provides insight into the conditions in which planet formation and migration occurs while the gas disk is still present. Recent studies done by Hoadley et al. 2015 and Banzatti & Pontipoddan 2015 suggest that gas in the inner disks of PPDs appear to "respond" to the loss of small dust grains with evolving PPD stage, and IR-CO emission may either be thermally or photo-excited by stellar UV radiation, depending on PPD evolutionary stage. Because far-UV H2 emission lines are dominantly photo-excited by stellar HI-Lyman alpha photons, we observe H2 absorption features against the stellar Lyman alpha wings in a large sample of PPDs at various evolutionary stages. We aim to characterize whether the inner disk H2 environment is in thermal equilibrium at various stages of PPD evolution. We use a sophisticated first-principles approach to fitting multiple absorption features along the red- and blue-wings of the observed stellar Lyman alpha profiles to extract column density estimates of H2 along the line of sight to the target. We find that the high kinetic energy H2 observed in absorption against the LyA wing may be described as a part of the thermal distribution with high kinetic temperature - a potential indication of an inner disk molecular hazy "envelope" around the cooler bulk disk. Ongoing research may help determine the state of the gas and whether it evolves with disk evolutionary stage.

Phase diagram and universality of the Lennard-Jones gas-liquid system.

PubMed

Watanabe, Hiroshi; Ito, Nobuyasu; Hu, Chin-Kun

2012-05-28

The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class.

Steady-state canopy gas exchange: system design and operation

NASA Technical Reports Server (NTRS)

Bugbee, B.

1992-01-01

This paper describes the use of a commercial growth chamber for canopy photosynthesis, respiration, and transpiration measurements. The system was designed to measure transpiration via water vapor fluxes, and the importance of this measurement is discussed. Procedures for continuous measurement of root-zone respiration are described, and new data is presented to dispel myths about sources of water vapor interference in photosynthesis and in the measurement of CO2 by infrared gas analysis. Mitchell (1992) has described the fundamentals of various approaches to measuring photosynthesis. Because our system evolved from experience with other types of single-leaf and canopy gas-exchange systems, it is useful to review advantages and disadvantages of different systems as they apply to various research objectives.

Combustion of Organic Molecules by the Thermal Decomposition of Perchlorate Salts: Implications for Organics at the Mars Phoenix Scout Landing Site

NASA Technical Reports Server (NTRS)

Ming, D.W.; Morris, R.V.; Niles, B.; Lauer, H.V.; Archer, P.D.; Sutter, B.; Boynton, W.V.; Golden, D.C.

2009-01-01

The Mars 2007 Phoenix Scout Mission successfully landed on May 25, 2008 and operated on the northern plains of Mars for 150 sols. The primary mission objective was to study the history of water and evaluate the potential for past and present habitability in Martian arctic ice-rich soil [1]. Phoenix landed near 68 N latitude on polygonal terrain created by ice layers that are a few centimeters under loose soil materials. The Phoenix Mission is assessing the potential for habitability by searching for organic molecules in the ice or icy soils at the landing site. Organic molecules are necessary building blocks for life, although their presence in the ice or soil does not indicate life itself. Phoenix searched for organic molecules by heating soil/ice samples in the Thermal and Evolved-Gas Analyzer (TEGA, [2]). TEGA consists of 8 differential scanning calorimeter (DSC) ovens integrated with a magnetic-sector mass spectrometer with a mass range of 2-140 daltons [2]. Endothermic and exothermic reactions are recorded by the TEGA DSC as samples are heated from ambient to 1000 C. Evolved gases, including any organic molecules and their fragments, are simultaneously measured by the mass spectrometer during heating. Phoenix TEGA data are still under analysis; however, no organic fragments have been identified to date in the evolved gas analysis (EGA). The MECA Wet Chemistry Lab (WCL) discovered a perchlorate salt in the Phoenix soils and a mass 32 peak evolved between 325 and 625 C for one surface sample dubbed Baby Bear [3]. The mass 32 peak is attributed to evolved O2 generated during the thermal decomposition of the perchlorate salt. Perchlorates are very strong oxidizers when heated, so it is possible that organic fragments evolved in the temperature range of 300-600 C were combusted by the O2 released during the thermal decomposition of the perchlorate salt. The byproduct of the combustion of organic molecules is CO2. There is a prominent release of CO2 between 200-600 C for several of the Phoenix soils analyzed by TEGA. This low temperature release of CO2 might be any combination of 1) desorption of adsorbed CO2, 2) thermal decomposition of Fe- and Mg-carbonates, and 3) combustion of organic molecules [2].

Interstellar clouds - From a dynamical perspective on their chemistry

NASA Technical Reports Server (NTRS)

Prasad, S. S.

1985-01-01

The possibility is examined that in the course of its dynamical evolution, a single mass of interstellar gas would exhibit properties of diffuse clouds, dense clouds and finally also of clouds perturbed by shocks or intense UV or X-ray radiation generated by a star of its own creation. This concept provides a common thread through the bewildering diversity of physical and chemical compositional properties shown by interstellar clouds. From this perspective, instead of being static objects, interstellar clouds are possibly incessantly evolving from initially diffuse to later dense state and then to star formation which ultimately restructures or disperses the remaining cloud material to begin the whole evolutionary process once again. Based on a simplified study of interstellar chemistry from a dynamical perspective, the ideas are presented as an heuristic: to encourage thought on the future direction of molecular astrophysics and the need to consider the chemical behavior of interstellar clouds in conjunction with, rather than in isolation from, their dynamical behavior. A physical basis must be sought for the semiempirical temperature formula which has been given a critical role in the collapse of diffuse clouds. Self-shielding effects in the chemistry of CO were neglected and this drawback should be removed; the ability of the model to explain the fractional abundances of more complex molecules, such as cyanopolyynes, should be examined.

Gas expulsion in highly substructured embedded star clusters

NASA Astrophysics Data System (ADS)

Farias, J. P.; Fellhauer, M.; Smith, R.; Domínguez, R.; Dabringhausen, J.

2018-06-01

We investigate the response of initially substructured, young, embedded star clusters to instantaneous gas expulsion of their natal gas. We introduce primordial substructure to the stars and the gas by simplistically modelling the star formation process so as to obtain a variety of substructure distributed within our modelled star-forming regions. We show that, by measuring the virial ratio of the stars alone (disregarding the gas completely), we can estimate how much mass a star cluster will retain after gas expulsion to within 10 per cent accuracy, no matter how complex the background structure of the gas is, and we present a simple analytical recipe describing this behaviour. We show that the evolution of the star cluster while still embedded in the natal gas, and the behaviour of the gas before being expelled, is crucial process that affect the time-scale on which the cluster can evolve into a virialized spherical system. Embedded star clusters that have high levels of substructure are subvirial for longer times, enabling them to survive gas expulsion better than a virialized and spherical system. By using a more realistic treatment for the background gas than our previous studies, we find it very difficult to destroy the young clusters with instantaneous gas expulsion. We conclude that gas removal may not be the main culprit for the dissolution of young star clusters.

Study on volatilization mechanism of ruthenium tetroxide from nitrosyl ruthenium nitrate by using mass spectrometer

NASA Astrophysics Data System (ADS)

Kato, Tetsuya; Usami, Tsuyoshi; Tsukada, Takeshi; Shibata, Yuki; Kodama, Takashi

2016-10-01

In a cooling malfunction accident of a high-level liquid waste (HLLW) tank, behavior of ruthenium (Ru) attracts much attention, since Ru could be oxidized to a volatile chemical form in the boiling and drying of HLLW, and part of radioactive Ru can potentially be released to the environment. In this study, nitrosyl Ru nitrate (Ru(NO)(NO3)3) dissolved in nitric acid (HNO3), which is commonly contained in a simulated HLLW, was dried and heated up to 723 K, and the evolved gas was introduced into a mass spectrometer. The well-known volatile species, ruthenium tetroxide (RuO4) was detected in a temperature range between 390 K and 500 K with the peak top around 440 K. Various gases such as HNO3, nitrogen dioxide (NO2), nitrogen monoxide (NO) also evolved due to evaporation of the nitric acid and decomposition of the nitrate ions. The ion current of RuO4 seems to increase with the increasing decomposition of nitrate, while the evaporation of HNO3 decreases. More volatilization of RuO4 was observed from the HNO3 solution containing not only Ru(NO)(NO3)3 but also cerium nitrate (Ce(NO3)3·6H2O) which was added for extra supply of nitrate ion, compared with that from the HNO3 solution containing only Ru(NO)(NO3)3. These experimental results suggest that Ru could be oxidized to form RuO4 by the nitrate ion as well as HNO3.

Testing alternative response designs for training forest disturbance and attribution models

Treesearch

T. Schroeder; G. Moisen; K. Schleeweis

2014-01-01

Understanding and modeling land cover and land use change is evolving into a foundational element of climate, environmental, and sustainability science. Land cover and land use data are core to applications such as carbon accounting, greenhouse gas emissions reporting, biomass and bioenergy assessments, hydrologic function assessments, fire and fuels planning and...

Nitrogen oxides from burning forest fuels examined by thermogravimetry and evolved gas analysis

Treesearch

H.B. Clements; Charles K. McMahon

1980-01-01

Abstract. Twelve forest fuels that varied widely in nitrogen content were burned in a thermogravimetric system, and nitrogen oxide production was analyzed by chemiluminescence. The effects of fuel nitrogen concentration, available oxygen, flow rate, and heating rate on nitrogen oxide production were examined.Results show that fuel nitrogen is an...

Molecular Astrophysics from Space: the Physical and Chemical Effects of Star Formation and the Destruction of Planetary Systems around Evolved Stars

NASA Technical Reports Server (NTRS)

Neufeld, David

2005-01-01

The research conducted during the reporting period is grouped into three sections: 1) Warm molecular gas in the interstellar medium (ISM); 2) Absorption line studies of "cold" molecular clouds; 3) Vaporization of comets around the AGB star IRC+10216.

Evolving School-Crisis Management since 9/11

ERIC Educational Resources Information Center

Brickman, Heather K.; Jones, Stephanie E.; Groom, Sara E.

2004-01-01

The word "terrorism" has become commonplace in the headlines, workplaces, and homes since September 11, 2001. In the past, school crisis plans commonly addressed how to evacuate in the event of a gas leak or fire. Today, schools must be prepared to address biological, chemical, and radiological attacks, as well as car bombings, suicide attacks,…

A rapid and cost effective method for soil carbon mineralization under static incubations

USDA-ARS?s Scientific Manuscript database

Soil incubations with subsequent measurement of carbon dioxide (CO2) evolved are common soil assays to estimate C mineralization rates and active organic C. Two common methods used to detect CO2 in laboratory incubations are gas chromatography (GC) and alkali absorption followed by titration (NaOH)...

A QUANTITATIVE STUDY OF THE EVOLUTION OF GASES FROM ELECTRON TUBES AND MATERIALS.

DTIC Science & Technology

spectrometer, ion pumps, ionization gauges and precision orifices to measure the flow rate of individual gases. It has been used to examine several...amounts comprise about 95% of the gas evolved during cathode conversion and activation. Additional experiments in the dynamic analysis of tube processes are suggested. (Author)

Dynamics of the baryonic component in hierarchical clustering universes

NASA Technical Reports Server (NTRS)

Navarro, Julio

1993-01-01

I present self-consistent 3-D simulations of the formation of virialized systems containing both gas and dark matter in a flat universe. A fully Lagrangian code based on the Smoothed Particle Hydrodynamics technique and a tree data structure has been used to evolve regions of comoving radius 2-3 Mpc. Tidal effects are included by coarse-sampling the density of the outer regions up to a radius approx. 20 Mpc. Initial conditions are set at high redshift (z greater than 7) using a standard Cold Dark Matter perturbation spectrum and a baryon mass fraction of 10 percent (omega(sub b) = 0.1). Simulations in which the gas evolves either adiabatically or radiates energy at a rate determined locally by its cooling function were performed. This allows us to investigate with the same set of simulations the importance of radiative losses in the formation of galaxies and the equilibrium structure of virialized systems where cooling is very inefficient. In the absence of radiative losses, the simulations can be rescaled to the density and radius typical of galaxy clusters. A summary of the main results is presented.

Novel Calibration Technique for a Coulometric Evolved Vapor Analyzer for Measuring Water Content of Materials

NASA Astrophysics Data System (ADS)

Bell, S. A.; Miao, P.; Carroll, P. A.

2018-04-01

Evolved vapor coulometry is a measurement technique that selectively detects water and is used to measure water content of materials. The basis of the measurement is the quantitative electrolysis of evaporated water entrained in a carrier gas stream. Although this measurement has a fundamental principle—based on Faraday's law which directly relates electrolysis current to amount of substance electrolyzed—in practice it requires calibration. Commonly, reference materials of known water content are used, but the variety of these is limited, and they are not always available for suitable values, materials, with SI traceability, or with well-characterized uncertainty. In this paper, we report development of an alternative calibration approach using as a reference the water content of humid gas of defined dew point traceable to the SI via national humidity standards. The increased information available through this new type of calibration reveals a variation of the instrument performance across its range not visible using the conventional approach. The significance of this is discussed along with details of the calibration technique, example results, and an uncertainty evaluation.

Investigating NO2 gas sensing behavior of flower-like MoS2 and rGO based nano-composite

NASA Astrophysics Data System (ADS)

Kanaujiya, Neha; Anupam, Golimar, Kapil; Pandey, Prateek Chandra; Jyoti, Varma, G. D.

2018-05-01

In the present work, MoS2 nano-sheets with flower-like morphology have been synthesized by facile hydrothermal method. The nano-composite of MoS2 and reduced graphene oxide (rGO) nano-sheets has been synthesized to study the gas sensing behavior. The structural and morphological characteristics of the as prepared samples are investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM) respectively. The gas sensing behavior of the as synthesized MoS2 and composite samples have been studied for different concentrations of NO2 at different temperatures. Improvement in sensing response of composite sample as compared to bare MoS2 sample has been observed. Percentage response of ˜ 23% has been observed at room temperature for 40ppm NO2. The detail correlation between gas sensing behavior and structural characteristics of the composite sample will be described and discussed in this paper.

Animal-Microbial Symbioses in Changing Environments

PubMed Central

Carey, Hannah V.; Duddleston, Khrystyne N.

2014-01-01

The environments in which animals have evolved and live have profound effects on all aspects of their biology. Predictable rhythmic changes in the physical environment are arguably among the most important forces shaping the evolution of behavior and physiology of animals, and to anticipate and prepare for these predictable changes animals have evolved biological clocks. Unpredictable changes in the physical environment have important impacts on animal biology as well. The ability of animals to cope with and survive unpredictable perturbations depends on phenotypic plasticity and/or microevolution. From the time metazoans first evolved from their protistan ancestors they have lived in close association with a diverse array of microbes that have influenced, in some way, all aspects of the evolution of animal structure, function and behavior. Yet, few studies have addressed whether daily or seasonal rhythms may affect, or be affected by, an animal’s microbial symbionts. This survey highlights how biologists interested in the ecological and evolutionary physiology of animals whose lifestyles are influenced by environmental cycles may benefit from considering whether symbiotic microbes have shaped the features they study. PMID:25086977

Cyclic spattering, seismic tremor, and surface fluctuation within a perched lava channel, Kīlauea Volcano

NASA Astrophysics Data System (ADS)

Patrick, Matthew R.; Orr, Tim; Wilson, David; Dow, David; Freeman, Richard

2011-08-01

In late 2007, a perched lava channel, built up to 45 m above the preexisting surface, developed during the ongoing eruption near Pu`u `Ō`ō cone on Kīlauea Volcano's east rift zone. The lava channel was segmented into four pools extending over a total of 1.4 km. From late October to mid-December, a cyclic behavior, consisting of steady lava level rise terminated by vigorous spattering and an abrupt drop in lava level, was commonly observed in pool 1. We use geologic observations, video, time-lapse camera images, and seismicity to characterize and understand this cyclic behavior. Spattering episodes occurred at intervals of 40-100 min during peak activity and involved small (5-10-m-high) fountains limited to the margins of the pool. Most spattering episodes had fountains which migrated downchannel. Each spattering episode was associated with a rapid lava level drop of about 1 m, which was concurrent with a conspicuous cigar-shaped tremor burst with peak frequencies of 4-5 Hz. We interpret this cyclic behavior to be gas pistoning, and this is the first documented instance of gas pistoning in lava well away from the deeper conduit. Our observations and data indicate that the gas pistoning was driven by gas accumulation beneath the visco-elastic component of the surface crust, contrary to other studies which attribute similar behavior to the periodic rise of gas slugs. The gas piston events typically had a gas mass of about 2,500 kg (similar to the explosions at Stromboli), with gas accumulation and release rates of about 1.1 and 5.7 kg s-1, respectively. The time-averaged gas output rate of the gas pistoning events accounted for about 1-2% of the total gas output rate of the east rift zone eruption.

Cyclic spattering, seismic tremor, and surface fluctuation within a perched lava channel, Kīlauea Volcano

USGS Publications Warehouse

Patrick, M.R.; Orr, T.; Wilson, D.; Dow, D.; Freeman, R.

2011-01-01

In late 2007, a perched lava channel, built up to 45 m above the preexisting surface, developed during the ongoing eruption near Pu‘u ‘Ō‘ō cone on Kīlauea Volcano’s east rift zone. The lava channel was segmented into four pools extending over a total of 1.4 km. From late October to mid-December, a cyclic behavior, consisting of steady lava level rise terminated by vigorous spattering and an abrupt drop in lava level, was commonly observed in pool 1. We use geologic observations, video, time-lapse camera images, and seismicity to characterize and understand this cyclic behavior. Spattering episodes occurred at intervals of 40–100 min during peak activity and involved small (5–10-m-high) fountains limited to the margins of the pool. Most spattering episodes had fountains which migrated downchannel. Each spattering episode was associated with a rapid lava level drop of about 1 m, which was concurrent with a conspicuous cigar-shaped tremor burst with peak frequencies of 4–5 Hz. We interpret this cyclic behavior to be gas pistoning, and this is the first documented instance of gas pistoning in lava well away from the deeper conduit. Our observations and data indicate that the gas pistoning was driven by gas accumulation beneath the visco-elastic component of the surface crust, contrary to other studies which attribute similar behavior to the periodic rise of gas slugs. The gas piston events typically had a gas mass of about 2,500 kg (similar to the explosions at Stromboli), with gas accumulation and release rates of about 1.1 and 5.7 kg s−1, respectively. The time-averaged gas output rate of the gas pistoning events accounted for about 1–2% of the total gas output rate of the east rift zone eruption.

Numerical study of heterogeneous mean temperature and shock wave in a resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yano, Takeru

2015-10-28

When a frequency of gas oscillation in an acoustic resonator is sufficiently close to one of resonant frequencies of the resonator, the amplitude of gas oscillation becomes large and hence the nonlinear effect manifests itself. Then, if the dissipation effects due to viscosity and thermal conductivity of the gas are sufficiently small, the gas oscillation may evolve into the acoustic shock wave, in the so-called consonant resonators. At the shock front, the kinetic energy of gas oscillation is converted into heat by the dissipation process inside the shock layer, and therefore the temperature of the gas in the resonator rises.more » Since the acoustic shock wave travels in the resonator repeatedly over and over again, the temperature rise becomes noticeable in due course of time even if the shock wave is weak. We numerically study the gas oscillation with shock wave in a resonator of square cross section by solving the initial and boundary value problem of the system of three-dimensional Navier-Stokes equations with a finite difference method. In this case, the heat conduction across the boundary layer on the wall of resonator causes a spatially heterogeneous distribution of mean (time-averaged) gas temperature.« less

Unit mechanisms of fission gas release: Current understanding and future needs

DOE PAGES

Tonks, Michael; Andersson, David; Devanathan, Ram; ...

2018-03-01

Gaseous fission product transport and release has a large impact on fuel performance, degrading fuel and gap properties. While gaseous fission product behavior has been investigated with bulk reactor experiments and simplified analytical models, recent improvements in experimental and modeling approaches at the atomistic and mesoscales are beginning to reveal new understanding of the unit mechanisms that define fission product behavior. Here, existing research on the basic mechanisms of fission gas release during normal reactor operation are summarized and critical areas where work is needed are identified. Here, this basic understanding of the fission gas behavior mechanisms has the potentialmore » to revolutionize our ability to predict fission product behavior and to design fuels with improved performance. In addition, this work can serve as a model on how a coupled experimental and modeling approach can be applied to understand the unit mechanisms behind other critical behaviors in reactor materials.« less

Unit mechanisms of fission gas release: Current understanding and future needs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonks, Michael; Andersson, David; Devanathan, Ram

Gaseous fission product transport and release has a large impact on fuel performance, degrading fuel and gap properties. While gaseous fission product behavior has been investigated with bulk reactor experiments and simplified analytical models, recent improvements in experimental and modeling approaches at the atomistic and mesoscales are beginning to reveal new understanding of the unit mechanisms that define fission product behavior. Here, existing research on the basic mechanisms of fission gas release during normal reactor operation are summarized and critical areas where work is needed are identified. Here, this basic understanding of the fission gas behavior mechanisms has the potentialmore » to revolutionize our ability to predict fission product behavior and to design fuels with improved performance. In addition, this work can serve as a model on how a coupled experimental and modeling approach can be applied to understand the unit mechanisms behind other critical behaviors in reactor materials.« less

Unit mechanisms of fission gas release: Current understanding and future needs

NASA Astrophysics Data System (ADS)

Tonks, Michael; Andersson, David; Devanathan, Ram; Dubourg, Roland; El-Azab, Anter; Freyss, Michel; Iglesias, Fernando; Kulacsy, Katalin; Pastore, Giovanni; Phillpot, Simon R.; Welland, Michael

2018-06-01

Gaseous fission product transport and release has a large impact on fuel performance, degrading fuel and gap properties. While gaseous fission product behavior has been investigated with bulk reactor experiments and simplified analytical models, recent improvements in experimental and modeling approaches at the atomistic and mesoscales are beginning to reveal new understanding of the unit mechanisms that define fission product behavior. Here, existing research on the basic mechanisms of fission gas release during normal reactor operation are summarized and critical areas where work is needed are identified. This basic understanding of the fission gas behavior mechanisms has the potential to revolutionize our ability to predict fission product behavior and to design fuels with improved performance. In addition, this work can serve as a model on how a coupled experimental and modeling approach can be applied to understand the unit mechanisms behind other critical behaviors in reactor materials.

ALMA observations of TiO2 around VY Canis Majoris

NASA Astrophysics Data System (ADS)

De Beck, E.; Vlemmings, W.; Muller, S.; Black, J. H.; O'Gorman, E.; Richards, A. M. S.; Baudry, A.; Maercker, M.; Decin, L.; Humphreys, E. M.

2015-08-01

Context. Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. To date, gas phase TiO2 has been detected only in the complex environment of the red supergiant VY CMa. Aims: We aim to constrain the distribution and excitation of TiO2 around VY CMa in order to clarify its role in dust formation. Methods: We analyse spectra and channel maps for TiO2 extracted from ALMA science verification data. Results: We detect 15 transitions of TiO2, and spatially resolve the emission for the first time. The maps demonstrate a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. An accelerating bipolar-like structure is found, oriented roughly east-west, of which the blue component runs into and breaks up around a solid continuum component. A distinct tail to the south-west is seen for some transitions, consistent with features seen in the optical and near-infrared. Conclusions: We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa. Appendix A is available in electronic form at http://www.aanda.org

Accurate Emission Line Diagnostics at High Redshift

NASA Astrophysics Data System (ADS)

Jones, Tucker

2017-08-01

How do the physical conditions of high redshift galaxies differ from those seen locally? Spectroscopic surveys have invested hundreds of nights of 8- and 10-meter telescope time as well as hundreds of Hubble orbits to study evolution in the galaxy population at redshifts z 0.5-4 using rest-frame optical strong emission line diagnostics. These surveys reveal evolution in the gas excitation with redshift but the physical cause is not yet understood. Consequently there are large systematic errors in derived quantities such as metallicity.We have used direct measurements of gas density, temperature, and metallicity in a unique sample at z=0.8 to determine reliable diagnostics for high redshift galaxies. Our measurements suggest that offsets in emission line ratios at high redshift are primarily caused by high N/O abundance ratios. However, our ground-based data cannot rule out other interpretations. Spatially resolved Hubble grism spectra are needed to distinguish between the remaining plausible causes such as active nuclei, shocks, diffuse ionized gas emission, and HII regions with escaping ionizing flux. Identifying the physical origin of evolving excitation will allow us to build the necessary foundation for accurate measurements of metallicity and other properties of high redshift galaxies. Only then can we expoit the wealth of data from current surveys and near-future JWST spectroscopy to understand how galaxies evolve over time.

Evolved Gas Analysis of Mars Analog Samples from the Arctic Mars Analog Svalbard Expedition: Implications for Analyses by the Mars Science Laboratory

NASA Technical Reports Server (NTRS)

McAdam, A.; Stern, J. C.; Mahaffy, P. R.; Blake, D. F.; Bristow, T.; Steele, A.; Amundsen, H. E. F.

2012-01-01

The 2011 Arctic Mars Analog Svalbard Expedition (AMASE) investigated several geologic settings on Svalbard, using methodologies and techniques being developed or considered for future Mars missions, such as the Mars Science Laboratory (MSL). The Sample Analysis at Mars (SAM) instrument suite on MSL consists of a quadrupole mass spectrometer (QMS), a gas chromatograph (GC), and a tunable laser spectrometer (TLS), which analyze gases created by pyrolysis of samples. During AMASE, a Hiden Evolved Gas Analysis-Mass Spectrometer (EGA-MS) system represented the EGA-QMS capability of SAM. Another MSL instrument, CheMin, will use x-ray diffraction (XRD) and x-ray fluorescence (XRF) to perform quantitative mineralogical characterization of samples. Field-portable versions of CheMin were used during AMASE. AMASE 2011 sites spanned a range of environments relevant to understanding martian surface materials, processes and habitability. They included the basaltic Sverrefjell volcano, which hosts carbonate globules, cements and coatings, carbonate and sulfate units at Colletth0gda, Devonian sandstone redbeds in Bockfjorden, altered basaltic lava delta deposits at Mt. Scott Keltie, and altered dolerites and volcanics at Botniahalvoya. Here we focus on SAM-like EGA-MS of a subset of the samples, with mineralogy comparisons to CheMin team results. The results allow insight into sample organic content as well as some constraints on sample mineralogy.

Dynamic properties of combustion instability in a lean premixed gas-turbine combustor.

PubMed

Gotoda, Hiroshi; Nikimoto, Hiroyuki; Miyano, Takaya; Tachibana, Shigeru

2011-03-01

We experimentally investigate the dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor from the viewpoint of nonlinear dynamics. A nonlinear time series analysis in combination with a surrogate data method clearly reveals that as the equivalence ratio increases, the dynamic behavior of the combustion instability undergoes a significant transition from stochastic fluctuation to periodic oscillation through low-dimensional chaotic oscillation. We also show that a nonlinear forecasting method is useful for predicting the short-term dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor, which has not been addressed in the fields of combustion science and physics.

Evolution of gas saturation and relative permeability during gas production from hydrate-bearing sediments: Gas invasion vs. gas nucleation

NASA Astrophysics Data System (ADS)

Jang, Jaewon; Santamarina, J. Carlos

2014-01-01

Capillarity and both gas and water permeabilities change as a function of gas saturation. Typical trends established in the discipline of unsaturated soil behavior are used when simulating gas production from hydrate-bearing sediments. However, the evolution of gas saturation and water drainage in gas invasion (i.e., classical soil behavior) and gas nucleation (i.e., gas production) is inherently different: micromodel experimental results show that gas invasion forms a continuous flow path while gas nucleation forms isolated gas clusters. Complementary simulations conducted using tube networks explore the implications of the two different desaturation processes. In spite of their distinct morphological differences in fluid displacement, numerical results show that the computed capillarity-saturation curves are very similar in gas invasion and nucleation (the gas-water interface confronts similar pore throat size distribution in both cases); the relative water permeability trends are similar (the mean free path for water flow is not affected by the topology of the gas phase); and the relative gas permeability is slightly lower in nucleation (delayed percolation of initially isolated gas-filled pores that do not contribute to gas conductivity). Models developed for unsaturated sediments can be used for reservoir simulation in the context of gas production from hydrate-bearing sediments, with minor adjustments to accommodate a lower gas invasion pressure Po and a higher gas percolation threshold.

Mechanosensation is evolutionarily tuned to locomotor mechanics

PubMed Central

Aiello, Brett R.; Westneat, Mark W.; Hale, Melina E.

2017-01-01

The biomechanics of animal limbs has evolved to meet the functional demands for movement associated with different behaviors and environments. Effective movement relies not only on limb mechanics but also on appropriate mechanosensory feedback. By comparing sensory ability and mechanics within a phylogenetic framework, we show that peripheral mechanosensation has evolved with limb biomechanics, evolutionarily tuning the neuromechanical system to its functional demands. We examined sensory physiology and mechanics of the pectoral fins, forelimb homologs, in the fish family Labridae. Labrid fishes exhibit extraordinary morphological and behavioral diversity and use pectoral fin-based propulsion with fins ranging in shape from high aspect ratio (AR) wing-like fins to low AR paddle-like fins. Phylogenetic character analysis demonstrates that high AR fins evolved independently multiple times in this group. Four pairs of species were examined; each included a plesiomorphic low AR and a high AR species. Within each species pair, the high AR species demonstrated significantly stiffer fin rays in comparison with the low AR species. Afferent sensory nerve activity was recorded during fin ray bending. In all cases, afferents of stiffer fins were more sensitive at lower displacement amplitudes, demonstrating mechanosensory tuning to fin mechanics and a consistent pattern of correlated evolution. We suggest that these data provide a clear example of parallel evolution in a complex neuromechanical system, with a strong link between multiple phenotypic characters: pectoral fin shape, swimming behavior, fin ray stiffness, and mechanosensory sensitivity. PMID:28396411

A group evolving-based framework with perturbations for link prediction

NASA Astrophysics Data System (ADS)

Si, Cuiqi; Jiao, Licheng; Wu, Jianshe; Zhao, Jin

2017-06-01

Link prediction is a ubiquitous application in many fields which uses partially observed information to predict absence or presence of links between node pairs. The group evolving study provides reasonable explanations on the behaviors of nodes, relations between nodes and community formation in a network. Possible events in group evolution include continuing, growing, splitting, forming and so on. The changes discovered in networks are to some extent the result of these events. In this work, we present a group evolving-based characterization of node's behavioral patterns, and via which we can estimate the probability they tend to interact. In general, the primary aim of this paper is to offer a minimal toy model to detect missing links based on evolution of groups and give a simpler explanation on the rationality of the model. We first introduce perturbations into networks to obtain stable cluster structures, and the stable clusters determine the stability of each node. Then fluctuations, another node behavior, are assumed by the participation of each node to its own belonging group. Finally, we demonstrate that such characteristics allow us to predict link existence and propose a model for link prediction which outperforms many classical methods with a decreasing computational time in large scales. Encouraging experimental results obtained on real networks show that our approach can effectively predict missing links in network, and even when nearly 40% of the edges are missing, it also retains stationary performance.

Review of Sector and Regional Trends in U.S. Electricity Markets. Focus on Natural Gas. Natural Gas and the Evolving U.S. Power Sector Monograph Series. Number 1 of 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Logan, Jeffrey; Medlock, III, Kenneth B.; Boyd, William C.

2015-10-15

This study explores dynamics related to natural gas use at the national, sectoral, and regional levels, with an emphasis on the power sector. It relies on a data set from SNL Financial to analyze recent trends in the U.S. power sector at the regional level. The research aims to provide decision and policy makers with objective and credible information, data, and analysis that informs their discussions of a rapidly changing energy system landscape. This study also summarizes regional changes in natural gas demand within the power sector. The transition from coal to natural gas is occurring rapidly along the entiremore » eastern portion of the country, but is relatively stagnant in the central and western regions. This uneven shift is occurring due to differences in fuel price costs, renewable energy targets, infrastructure constraints, historical approach to regulation, and other factors across states.« less

Formation of jets in Comet 19P/Borrelly by subsurface geysers

USGS Publications Warehouse

Yelle, R.V.; Soderblom, L.A.; Jokipii, J.R.

2004-01-01

Observations of the inner coma of Comet 19P/Borrelly with the camera on the Deep Space 1 spacecraft revealed several highly collimated dust jets emanating from the nucleus. The observed jets can be produced by acceleration of evolved gas from a subsurface cavity through a narrow orifice to the surface. As long as the cavity is larger than the orifice, the pressure in the cavity will be greater than the ambient pressure in the coma and the flow from the geyser will be supersonic. The gas flow becomes collimated as the sound speed is approached and dust entrainment in the gas flow creates the observed jets. Outside the cavity, the expanding gas loses its collimated character, but the density drops rapidly decoupling the dust and gas, allowing the dust to continue in a collimated beam. The hypothesis proposed here can explain the jets seen in the inner coma of Comet 1P/Halley as well, and may be a primary mechanism for cometary activity. ?? 2003 Published by Elsevier Inc.

Organic Combustion in the Presence of Ca-Carbonate and Mg-Perchlorate: A Possible Source for the Low Temperature CO2 Release Seen in Mars Phoenix Thermal and Evolved Gas Analyzer Data

NASA Technical Reports Server (NTRS)

Archer, Douglas; Ming, D.; Niles, P.; Sutter, B.; Lauer, H.

2012-01-01

Two of the most important discoveries of the Phoenix Lander were the detection of approx.0.6% perchlorate [1] and 3-5% carbonate [2] in landing site soils. The Thermal and Evolved Gas Analyzer (TEGA) instrument on the Phoenix lander could heat samples up to approx.1000 C and monitor evolved gases with a mass spectrometer. TEGA detected a low (approx.350 C) and high (approx.750 C) temperature CO2 release. The high temp release was attributed to the thermal decomposition of Ca-carbonate (calcite). The low temperature CO2 release could be due to desorption of CO2, decomposition of a different carbonate mineral, or the combustion of organic material. A new hypothesis has also been proposed that the low temperature CO2 release could be due to the early breakdown of calcite in the presence of the decomposition products of certain perchlorate salts [3]. We have investigated whether or not this new hypothesis is also compatible with organic combustion. Magnesium perchlorate is stable as Mg(ClO4)2-6H2O on the martian surface [4]. During thermal decomposition, this perchlorate salt releases H2O, Cl2, and O2 gases. The Cl2 can react with water to form HCl which then reacts with calcite, releasing CO2 below the standard thermal decomposition temperature of calcite. However, when using concentrations of perchlorate and calcite similar to what was detected by Phoenix, the ratio of high:low temperature CO2 evolved is much larger in the lab, indicating that although this process might contribute to the low temp CO2 release, it cannot account for all of it. While H2O and Cl2 cause calcite decomposition, the O2 evolved during perchlorate decomposition can lead to the combustion of any reduced carbon present in the sample [5]. We investigate the possible contribution of organic molecules to the low temperature CO2 release seen on Mars.

Perceived Maternal Behavioral Control, Infant Behavior, and Milk Supply: A Qualitative Study.

PubMed

Peacock-Chambers, Elizabeth; Dicks, Kaitlin; Sarathy, Leela; Brown, Allison A; Boynton-Jarrett, Renée

Disparities persist in breastfeeding exclusivity and duration despite increases in breastfeeding initiation. The objective of this study was to examine factors that influence maternal decision making surrounding infant feeding practices over time in a diverse inner-city population. We conducted a prospective qualitative study with 20 mothers recruited from 2 urban primary care clinics. Participants completed open-ended interviews and demographic questionnaires in English or Spanish administered at approximately 2 weeks and 6 months postpartum. Transcripts were analyzed using a combined technique of inductive (data-driven) and deductive (theory-driven, based on the Theory of Planned Behavior) thematic analysis using 3 independent coders and iterative discussion to reach consensus. All women initiated breastfeeding, and 65% reported perceived insufficient milk (PIM). An association between PIM and behavioral control emerged as the overarching theme impacting early breastfeeding cessation and evolved over time. Early postpartum, PIM evoked maternal distress-strong emotional responses to infant crying and need to control infant behaviors. Later, mothers accepted a perceived lack of control over milk supply with minimal distress or as a natural process. Decisions to stop breastfeeding occurred through an iterative process, informed by trials of various strategies and observations of subsequent changes in infant behavior, strongly influenced by competing psychosocial demands. Infant feeding decisions evolve over time and are influenced by perceptions of control over infant behavior and milk supply. Tailored anticipatory guidance is needed to provide time-sensitive strategies to cope with challenging infant behaviors and promote maternal agency over breastfeeding in low-income populations.

ROSAT HRI images of Abell 85 and Abell 496: Evidence for inhomogeneities in cooling flows

NASA Technical Reports Server (NTRS)

Prestwich, Andrea H.; Guimond, Stephen J.; Luginbuhl, Christian B.; Joy, Marshall

1995-01-01

We present ROSAT high-resolution images of two clusters of galaxies with cooling flows, Abell 496 and Abell 85. In these clusters, X-ray emission on small scales above the general cluster emission is significant at the 3 sigma level. There is no evidence for optical counterparts. If real, the enhancements may be associated with clumps of gas at a lower temperature and higher density than the ambient medium, or hotter, denser gas perhaps compressed by magnetic fields. These observations can be used to test models of how thermal instabilities form and evolve in cooling flows.

ROSAT HRI images of Abell 85 and Abell 496: Evidence for inhomogeneities in cooling flows

NASA Technical Reports Server (NTRS)

Prestwich, Andrea H.; Guimond, Stephen J.; Luginbuhl, Christian; Joy, Marshall

1994-01-01

We present ROSAT HRI images of two clusters of galaxies with cooling flows, Abell 496 and Abell 85. In these clusters, x-ray emission on small scales above the general cluster emission is significant at the 3 sigma level. There is no evidence for optical counterparts. The enhancements may be associated with lumps of gas at a lower temperature and higher density than the ambient medium, or hotter, denser gas perhaps compressed by magnetic fields. These observations can be used to test models of how thermal instabilities form and evolve in cooling flows.

Evolution and plasticity: Divergence of song discrimination is faster in birds with innate song than in song learners in Neotropical passerine birds.

PubMed

Freeman, Benjamin G; Montgomery, Graham A; Schluter, Dolph

2017-09-01

Plasticity is often thought to accelerate trait evolution and speciation. For example, plasticity in birdsong may partially explain why clades of song learners are more diverse than related clades with innate song. This "song learning" hypothesis predicts that (1) differences in song traits evolve faster in song learners, and (2) behavioral discrimination against allopatric song (a proxy for premating reproductive isolation) evolves faster in song learners. We tested these predictions by analyzing acoustic traits and conducting playback experiments in allopatric Central American sister pairs of song learning oscines (N = 42) and nonlearning suboscines (N = 27). We found that nonlearners evolved mean acoustic differences slightly faster than did leaners, and that the mean evolutionary rate of song discrimination was 4.3 times faster in nonlearners than in learners. These unexpected results may be a consequence of significantly greater variability in song traits in song learners (by 54-79%) that requires song-learning oscines to evolve greater absolute differences in song before achieving the same level of behavioral song discrimination as nonlearning suboscines. This points to "a downside of learning" for the evolution of species discrimination, and represents an important example of plasticity reducing the rate of evolution and diversification by increasing variability. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Collective action and the evolution of social norm internalization

PubMed Central

Gavrilets, Sergey; Richerson, Peter J.

2017-01-01

Human behavior is strongly affected by culturally transmitted norms and values. Certain norms are internalized (i.e., acting according to a norm becomes an end in itself rather than merely a tool in achieving certain goals or avoiding social sanctions). Humans’ capacity to internalize norms likely evolved in our ancestors to simplify solving certain challenges—including social ones. Here we study theoretically the evolutionary origins of the capacity to internalize norms. In our models, individuals can choose to participate in collective actions as well as punish free riders. In making their decisions, individuals attempt to maximize a utility function in which normative values are initially irrelevant but play an increasingly important role if the ability to internalize norms emerges. Using agent-based simulations, we show that norm internalization evolves under a wide range of conditions so that cooperation becomes “instinctive.” Norm internalization evolves much more easily and has much larger effects on behavior if groups promote peer punishment of free riders. Promoting only participation in collective actions is not effective. Typically, intermediate levels of norm internalization are most frequent but there are also cases with relatively small frequencies of “oversocialized” individuals willing to make extreme sacrifices for their groups no matter material costs, as well as “undersocialized” individuals completely immune to social norms. Evolving the ability to internalize norms was likely a crucial step on the path to large-scale human cooperation. PMID:28533363

Collective action and the evolution of social norm internalization.

PubMed

Gavrilets, Sergey; Richerson, Peter J

2017-06-06

Human behavior is strongly affected by culturally transmitted norms and values. Certain norms are internalized (i.e., acting according to a norm becomes an end in itself rather than merely a tool in achieving certain goals or avoiding social sanctions). Humans' capacity to internalize norms likely evolved in our ancestors to simplify solving certain challenges-including social ones. Here we study theoretically the evolutionary origins of the capacity to internalize norms. In our models, individuals can choose to participate in collective actions as well as punish free riders. In making their decisions, individuals attempt to maximize a utility function in which normative values are initially irrelevant but play an increasingly important role if the ability to internalize norms emerges. Using agent-based simulations, we show that norm internalization evolves under a wide range of conditions so that cooperation becomes "instinctive." Norm internalization evolves much more easily and has much larger effects on behavior if groups promote peer punishment of free riders. Promoting only participation in collective actions is not effective. Typically, intermediate levels of norm internalization are most frequent but there are also cases with relatively small frequencies of "oversocialized" individuals willing to make extreme sacrifices for their groups no matter material costs, as well as "undersocialized" individuals completely immune to social norms. Evolving the ability to internalize norms was likely a crucial step on the path to large-scale human cooperation.

An analytical approach of thermodynamic behavior in a gas target system on a medical cyclotron.

PubMed

Jahangiri, Pouyan; Zacchia, Nicholas A; Buckley, Ken; Bénard, François; Schaffer, Paul; Martinez, D Mark; Hoehr, Cornelia

2016-01-01

An analytical model has been developed to study the thermo-mechanical behavior of gas targets used to produce medical isotopes, assuming that the system reaches steady-state. It is based on an integral analysis of the mass and energy balance of the gas-target system, the ideal gas law, and the deformation of the foil. The heat transfer coefficients for different target bodies and gases have been calculated. Excellent agreement is observed between experiments performed at TRIUMF's 13 MeV cyclotron and the model. Copyright © 2015 Elsevier Ltd. All rights reserved.

High burnup fuel behavior related to fission gas effects under reactivity initiated accidents (RIA) conditions

NASA Astrophysics Data System (ADS)

Lemoine, F.

1997-09-01

Specific aspects of irradiated fuel result from the increasing retention of gaseous and volatile fission products with burnup, which, under overpower conditions, can lead to solid fuel pressurization and swelling causing severe PCMI (pellet clad mechanical interaction). In order to assess the reliability of high burnup fuel under RIAs, experimental programs have been initiated which have provided important data concerning the transient fission gas behavior and the clad loading mechanisms. The importance of the rim zone is demonstrated based on three experiments resulting in clad failure at low enthalpy, which are explained by energetic considerations. High gas release in non-failure tests with low energy deposition underlines the importance of grain boundary and porosity gas. Measured final releases are strongly correlated to the microstructure evolution, depending on energy deposition, pulse width, initial and refabricated fuel rod design. Observed helium release can also increase internal pressure and gives hints to the gas behavior understanding.

Equation of state of an ideal gas with nonergodic behavior in two connected vessels.

PubMed

Naplekov, D M; Semynozhenko, V P; Yanovsky, V V

2014-01-01

We consider a two-dimensional collisionless ideal gas in the two vessels connected through a small hole. One of them is a well-behaved chaotic billiard, another one is known to be nonergodic. A significant part of the second vessel's phase space is occupied by an island of stability. In the works of Zaslavsky and coauthors, distribution of Poincaré recurrence times in similar systems was considered. We study the gas pressure in the vessels; it is uniform in the first vessel and not uniform in second one. An equation of the gas state in the first vessel is obtained. Despite the very different phase-space structure, behavior of the second vessel is found to be very close to the behavior of a good ergodic billiard but of different volume. The equation of state differs from the ordinary equation of ideal gas state by an amendment to the vessel's volume. Correlation of this amendment with a share of the phase space under remaining intact islands of stability is shown.

An investigation into the flow behavior of a single phase gas system and a two phase gas/liquid system in normal gravity with nonuniform heating from above

NASA Technical Reports Server (NTRS)

Disimile, Peter J.; Heist, Timothy J.

1990-01-01

The fluid behavior in normal gravity of a single phase gas system and a two phase gas/liquid system in an enclosed circular cylinder heated suddenly and nonuniformly from above was investigated. Flow visualization was used to obtain qualitative data on both systems. The use of thermochromatic liquid crystal particles as liquid phase flow tracers was evaluated as a possible means of simultaneously gathering both flow pattern and temperature gradient data for the two phase system. The results of the flow visualization experiments performed on both systems can be used to gain a better understanding of the behavior of such systems in a reduced gravity environment and aid in the verification of a numerical model of the system.

Southern Pine Beetle Behavior and Semiochemistry

Treesearch

Brian T. Sullivan

2011-01-01

The southern pine beetle (SPB) feeds both as adults and larvae within the inner bark of pine trees, which invariably die as a result of colonization. Populations of the SPB erupt periodically and produce catastrophic losses of pines, while at other times the beetles persist almost undetectably in the environment. The southern pine beetle has evolved behaviors that...

A Model for the Transfer of Perceptual-Motor Skill Learning in Human Behaviors

ERIC Educational Resources Information Center

Rosalie, Simon M.; Muller, Sean

2012-01-01

This paper presents a preliminary model that outlines the mechanisms underlying the transfer of perceptual-motor skill learning in sport and everyday tasks. Perceptual-motor behavior is motivated by performance demands and evolves over time to increase the probability of success through adaptation. Performance demands at the time of an event…

Integrating Behavioral-Motive and Experiential-Requirement Perspectives on Psychological Needs: A Two Process Model

ERIC Educational Resources Information Center

Sheldon, Kennon M.

2011-01-01

Psychological need theories offer much explanatory potential for behavioral scientists, but there is considerable disagreement and confusion about what needs are and how they work. A 2-process model of psychological needs is outlined, viewing needs as evolved functional systems that provide both (a) innate psychosocial motives that tend to impel…

FORUM: Affective Learning. Affective Learning: Evolving from Values and Planned Behaviors to Internalization and Pervasive Behavioral Change

ERIC Educational Resources Information Center

Thweatt, Katherine S.; Wrench, Jason S.

2015-01-01

The mission of "Communication Education" is to publish the best research on communication and learning. Researchers study the communication-learning interface in many ways, but a common approach is to explore how instructor and student communication can lead to better learning outcomes. Although scholars have long classified learning…

Fungus cultivation by ambrosia beetles: Behavior and laboratory breeding success in three Xyleborine species

Treesearch

Peter Biedermann; Kier Klepzig; Taborsky Michael

2009-01-01

Fungus cultivation by ambrosia beetles is one of the four independently evolved cases of agriculture known in animals. Such cultivation is most advanced in the highly social subtribe Xyleborina (Scolytinae), which is characterized by haplodiploidy and extreme levels of inbreeding. Despite their ubiquity in forests worldwide, the behavior of these beetles remains poorly...

Teen Sexual Behavior. A Leader's Resource of Practical Strategies with Youth.

ERIC Educational Resources Information Center

Berne, Linda A.; Wild, Pamela

The purpose of this book is to assist leaders in a variety of settings to address young people on the critical issues of teenage sexuality. The units are presented in a sequential pattern which covers teenage sexual behavior as it naturally evolves. Detailed information and precise directions for presenting the lessons are featured. The curriculum…

The Developmental Trajectories of Peer Victimization in Middle to Late Childhood and the Changing Nature of Their Behavioral Correlates

ERIC Educational Resources Information Center

Boivin, Michel; Petitclerc, Amelie; Feng, Bei; Barker, Edward D.

2010-01-01

This study investigated the evolving relations between peer victimization and social/emotional difficulties in middle to late childhood. Peer assessments of peer victimization and social/emotional difficulties (aggressive behavior, social withdrawal, and emotional vulnerability) were collected over 4 years for 1,035 children attending Grades 3-6…

Consensus in evolving networks of mobile agents

NASA Astrophysics Data System (ADS)

Baronchelli, Andrea; Díaz-Guilera, Albert

2012-02-01

Populations of mobile and communicating agents describe a vast array of technological and natural systems, ranging from sensor networks to animal groups. Here, we investigate how a group-level agreement may emerge in the continuously evolving networks defined by the local interactions of the moving individuals. We adopt a general scheme of motion in two dimensions and we let the individuals interact through the minimal naming game, a prototypical scheme to investigate social consensus. We distinguish different regimes of convergence determined by the emission range of the agents and by their mobility, and we identify the corresponding scaling behaviors of the consensus time. In the same way, we rationalize also the behavior of the maximum memory used during the convergence process, which determines the minimum cognitive/storage capacity needed by the individuals. Overall, we believe that the simple and general model presented in this talk can represent a helpful reference for a better understanding of the behavior of populations of mobile agents.

Evolved differences in larval social behavior mediated by novel pheromones

PubMed Central

Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

2014-01-01

Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects. DOI: http://dx.doi.org/10.7554/eLife.04205.001 PMID:25497433

Physical gills prevent drowning of many wetland insects, spiders and plants.

PubMed

Pedersen, Ole; Colmer, Timothy D

2012-03-01

Insects, spiders and plants risk drowning in their wetland habitats. The slow diffusion of O(2) can cause asphyxiation when underwater, as O(2) supply cannot meet respiratory demands. Some animals and plants have found a common solution to the major challenge: how to breathe underwater with respiratory systems evolved for use in air? Hydrophobic surfaces on their bodies possess gas films that act as a 'physical gill' to collect O(2) when underwater and thus sustain respiration. In aquatic insects, this feature/process has been termed 'plastron respiration'. Here, we demonstrate the similarities in function between underwater respiration of insect (Aphelocheirus aestivalis) plastrons and gas films on leaves of wetland plants (Phalaris arundinacea) and also show the importance of these physical gills by the resulting changes upon their removal. The gas films provide an enlarged gas-water interface to enhance O(2) uptake underwater that is above that if only spiracles (insects) or stomata (plants) provided the gas-phase contact with the water. Body-surface gas films contribute to the survival of many insects, spiders and plants in aquatic and flood-prone environments.

Gas Removal in the Ursa Minor Galaxy: Linking Hydrodynamics and Chemical Evolution Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caproni, Anderson; Lanfranchi, Gustavo Amaral; Baio, Gabriel Henrique Campos

2017-04-01

We present results from a non-cosmological, three-dimensional hydrodynamical simulation of the gas in the dwarf spheroidal galaxy Ursa Minor. Assuming an initial baryonic-to-dark-matter ratio derived from the cosmic microwave background radiation, we evolved the galactic gas distribution over 3 Gyr, taking into account the effects of the types Ia and II supernovae. For the first time, we used in our simulation the instantaneous supernovae rates derived from a chemical evolution model applied to spectroscopic observational data of Ursa Minor. We show that the amount of gas that is lost in this process is variable with time and radius, being themore » highest rates observed during the initial 600 Myr in our simulation. Our results indicate that types Ia and II supernovae must be essential drivers of the gas loss in Ursa Minor galaxy (and probably in other similar dwarf galaxies), but it is ultimately the combination of galactic winds powered by these supernovae and environmental effects (e.g., ram-pressure stripping) that results in the complete removal of the gas content.« less

Unit mechanisms of fission gas release: Current understanding and future needs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonks, Michael; Andersson, David; Devanathan, Ram

Gaseous fission product transport and release has a large impact on fuel performance, degrading fuel properties and, once the gas is released into the gap between the fuel and cladding, lowering gap thermal conductivity and increasing gap pressure. While gaseous fission product behavior has been investigated with bulk reactor experiments and simplified analytical models, recent improvements in experimental and modeling approaches at the atomistic and mesoscales are being applied to provide unprecedented understanding of the unit mechanisms that define the fission product behavior. In this article, existing research on the basic mechanisms behind the various stages of fission gas releasemore » during normal reactor operation are summarized and critical areas where experimental and simulation work is needed are identified. This basic understanding of the fission gas behavior mechanisms has the potential to revolutionize our ability to predict fission product behavior during reactor operation and to design fuels that have improved fission product retention. In addition, this work can serve as a model on how a coupled experimental and modeling approach can be applied to understand the unit mechanisms behind other critical behaviors in reactor materials.« less

Rate Theory Modeling and Simulation of Silicide Fuel at LWR Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Yinbin; Ye, Bei; Hofman, Gerard

As a promising candidate for the accident tolerant fuel (ATF) used in light water reactors (LWRs), the fuel performance of uranium silicide (U 3Si 2) at LWR conditions needs to be well understood. In this report, rate theory model was developed based on existing experimental data and density functional theory (DFT) calculations so as to predict the fission gas behavior in U 3Si 2 at LWR conditions. The fission gas behavior of U 3Si 2 can be divided into three temperature regimes. During steady-state operation, the majority of the fission gas stays in intragranular bubbles, whereas the dominance of intergranularmore » bubbles and fission gas release only occurs beyond 1000 K. The steady-state rate theory model was also used as reference to establish a gaseous swelling correlation of U 3Si 2 for the BISON code. Meanwhile, the overpressurized bubble model was also developed so that the fission gas behavior at LOCA can be simulated. LOCA simulation showed that intragranular bubbles are still dominant after a 70 second LOCA, resulting in a controllable gaseous swelling. The fission gas behavior of U 3Si 2 at LWR conditions is benign according to the rate theory prediction at both steady-state and LOCA conditions, which provides important references to the qualification of U 3Si 2 as a LWR fuel material with excellent fuel performance and enhanced accident tolerance.« less

Nesting behaviour influences species-specific gas exchange across avian eggshells.

PubMed

Portugal, Steven J; Maurer, Golo; Thomas, Gavin H; Hauber, Mark E; Grim, Tomáš; Cassey, Phillip

2014-09-15

Carefully controlled gas exchange across the eggshell is essential for the development of the avian embryo. Water vapour conductance (G(H2O)) across the shell, typically measured as mass loss during incubation, has been demonstrated to optimally ensure the healthy development of the embryo while avoiding desiccation. Accordingly, eggs exposed to sub-optimal gas exchange have reduced hatching success. We tested the association between eggshell G(H2O) and putative life-history correlates of adult birds, ecological nest parameters and physical characteristics of the egg itself to investigate how variation in G(H2O) has evolved to maintain optimal water loss across a diverse set of nest environments. We measured gas exchange through eggshell fragments in 151 British breeding bird species and fitted phylogenetically controlled, general linear models to test the relationship between G(H2O) and potential predictor parameters of each species. Of our 17 life-history traits, only two were retained in the final model: wet-incubating parent and nest type. Eggs of species where the parent habitually returned to the nest with wet plumage had significantly higher G(H2O) than those of parents that returned to the nest with dry plumage. Eggs of species nesting in ground burrows, cliffs and arboreal cups had significantly higher G(H2O) than those of species nesting on the ground in open nests or cups, in tree cavities and in shallow arboreal nests. Phylogenetic signal (measured as Pagel's λ) was intermediate in magnitude, suggesting that differences observed in the G(H2O) are dependent upon a combination of shared ancestry and species-specific life history and ecological traits. Although these data are correlational by nature, they are consistent with the hypothesis that parents constrained to return to the nest with wet plumage will increase the humidity of the nest environment, and the eggs of these species have evolved a higher G(H2O) to overcome this constraint and still achieve optimal water loss during incubation. We also suggest that eggs laid in cup nests and burrows may require a higher G(H2O) to overcome the increased humidity as a result from the confined nest microclimate lacking air movements through the nest. Taken together, these comparative data imply that species-specific levels of gas exchange across avian eggshells are variable and evolve in response to ecological and physical variation resulting from parental and nesting behaviours. © 2014. Published by The Company of Biologists Ltd.

Induced massive star formation in the trifid nebula?

PubMed

Cernicharo; Lefloch; Cox; Cesarsky; Esteban; Yusef-Zadeh; Mendez; Acosta-Pulido; Garcia Lopez RJ; Heras

1998-10-16

The Trifid nebula is a young (10(5) years) galactic HII region where several protostellar sources have been detected with the infrared space observatory. The sources are massive (17 to 60 solar masses) and are associated with molecular gas condensations at the edges or inside the nebula. They appear to be in an early evolutionary stage and may represent the most recent generation of stars in the Trifid. These sources range from dense, apparently still inactive cores to more evolved sources, undergoing violent mass ejection episodes, including a source that powers an optical jet. These observations suggest that the protostellar sources may have evolved by induced star formation in the Trifid nebula.

The Ice Line in Pre-Solar Protoplanetary Disks

NASA Technical Reports Server (NTRS)

Davis, Sanford S.

2012-01-01

Protoplanetary disks contain abundant quantities of water molecules in both gas and solid phases. The distribution of these two phases in an evolving protoplanetary disk will have important consequences regarding water sequestration in planetary embryos. The boundary between gaseous and solid water is the "ice line" or "snow line" A simplified model that captures the complicated two-branched structure of the ice line is developed and compared with recent investigations. The effect of an evolving Sun is also included for the first time. This latter parameter could have important consequences regarding the thermodynamic state and the surface reaction environment for the time-dependent chemical reactions occurring during the 1- to 10-million-year lifetime of the pre-solar disk.

Anomalous effective dimensionality of quantum gas adsorption near nanopores.

PubMed

Full, Steven J; McNutt, Jessica P; Cole, Milton W; Mbaye, Mamadou T; Gatica, Silvina M

2010-08-25

Three problems involving quasi-one-dimensional (1D) ideal gases are discussed. The simplest problem involves quantum particles localized within the 'groove', a quasi-1D region created by two adjacent, identical and parallel nanotubes. At low temperature (T), the transverse motion of the adsorbed gas, in the plane perpendicular to the axes of the tubes, is frozen out. Then, the low T heat capacity C(T) of N particles is that of a 1D classical gas: C(*)(T) = C(T)/(Nk(B)) --> 1/2. The dimensionless heat capacity C(*) increases when T ≥ 0.1T(x, y) (transverse excitation temperatures), asymptoting at C(*) = 2.5. The second problem involves a gas localized between two nearly parallel, co-planar nanotubes, with small divergence half-angle γ. In this case, too, the transverse motion does not contribute to C(T) at low T, leaving a problem of a gas of particles in a 1D harmonic potential (along the z axis, midway between the tubes). Setting ω(z) as the angular frequency of this motion, for T ≥ τ(z) ≡ ω(z)ħ/k(B), the behavior approaches that of a 2D classical gas, C(*) = 1; one might have expected instead C(*) = 1/2, as in the groove problem, since the limit γ ≡ 0 is 1D. For T < τ(z), the thermal behavior is exponentially activated, C(*) ∼ (τ(z)/T)(2)e(-τ(z)/T). At higher T (T ≈ ε(y)/k(B) ≡ τ(y) > τ(z)), motion is excited in the y direction, perpendicular to the plane of nanotubes, resulting in thermal behavior (C(*) = 7/4) corresponding to a gas in 7/2 dimensions, while at very high T (T > ħω(x)/k(B) ≡ τ(x) > τ(y)), the behavior becomes that of a D = 11/2 system. The third problem is that of a gas of particles, e.g. (4)He, confined in the interstitial region between four square parallel pores. The low T behavior found in this case is again surprising--that of a 5D gas.

The Co-evolution of Concepts and Motivation

PubMed Central

Delton, Andrew W.; Sell, Aaron

2014-01-01

Does the human mind contain evolved concepts? Many psychologists have doubted this or have investigated only a narrow set (e.g., object, number, cause). Does the human mind contain evolved motivational systems? Many more assent to this claim, holding that there are evolved motivational systems for, among other tasks, social affiliation, aggressive competition, and finding food. An emerging research program, however, reveals that these are not separate questions. Any evolved motivational system needs a wealth of conceptual structure that tethers the motivations to real world entities. For instance, what use is a fear of predators without knowing what predators are and how to respond to them effectively? As we illustrate with case studies of cooperation and conflict, there is no motivation without representation: To generate adaptive behavior, motivational systems must be interwoven with the concepts required to support them, and cannot be understood without explicit reference to those concepts. PMID:25221389

The Co-evolution of Concepts and Motivation.

PubMed

Delton, Andrew W; Sell, Aaron

2014-04-01

Does the human mind contain evolved concepts? Many psychologists have doubted this or have investigated only a narrow set (e.g., object, number, cause). Does the human mind contain evolved motivational systems? Many more assent to this claim, holding that there are evolved motivational systems for, among other tasks, social affiliation, aggressive competition, and finding food. An emerging research program, however, reveals that these are not separate questions. Any evolved motivational system needs a wealth of conceptual structure that tethers the motivations to real world entities. For instance, what use is a fear of predators without knowing what predators are and how to respond to them effectively? As we illustrate with case studies of cooperation and conflict, there is no motivation without representation: To generate adaptive behavior, motivational systems must be interwoven with the concepts required to support them, and cannot be understood without explicit reference to those concepts.

Implications of a Culturally Evolved Self for Notions of Free Will

PubMed Central

Robertson, Lloyd Hawkeye

2017-01-01

Most schools in psychology have emphasized individual choice despite evidence of genetic and cultural determinism. It is suggested in this paper that the rejection of classical behaviorism by psychology and other humanities flowed from deeply held cultural assumptions about volition and free will. While compatibilists have suggested that notions of free will and determinism are not mutually exclusive, the psychological mechanisms by which such an accommodation could be explained have been inadequately explored. Drawing on research into classical cultures, this paper builds an argument that the notion of free will was adaptive flowing from culturally evolved changes to the self, and that this “evolved self,” containing assumptions of personal volition, continuity, and reason, became benchmarks of what it means to be human. The paper proposes a model of a culturally evolved self that is compatible with understandings of free will and determinism. Implications for therapeutic practice and future research are discussed. PMID:29163273

How does the association of iron oxides and perchlorate salts influence organic matter evolution when using Sample Analysis at Mars pyrolysis onboard Curiosity?

NASA Astrophysics Data System (ADS)

François, Pascaline; Coll, Patrice; Szopa, Cyril; Buch, Arnaud; Cabane, Michel; McAdam, Amy; Freissinet, Caroline; Eigenbrode, Jennifer L.; Glavin, Daniel P.; Navarro-Gonzalez, Rafael; Mahaffy, Paul R.

2014-05-01

The Sample Analysis at Mars (SAM) instrument suite aboard the Curiosity rover is designed to characterize organic and inorganic volatiles thermally evolved from solid samples. It can analyze evolved volatiles directly with its quadrupole mass spectrometer (MS) to perform evolved gas analysis (EGA) or it can analyze volatiles after they have been sent through a gas chromatography column to perform pyrolysis-gas chromatograph-mass spectrometry (pyr-GC-MS) [1]. Three solid samples have been analyzed by SAM, a scoop of basaltic sand at Rocknest (RN) and two rocks drilled at Yellowknife Bay designated as John Klein (JK) and Cumberland (CB). All these samples contain an oxychlorine phase (e.g., a perchlorate salt) [2, 3] that evolves HCl, Cl2 and O2 on heating leading to the possible chlorination and/or combustion of organic molecules [4]. Chlorohydrocarbons detected at RN, JK and CB are derived from reactions between martian oxychlorine compounds and terrestrial carbon that is part of the SAM background (e.g., MTBSTFA [2]) as well as potentially reactions with martian carbon and/or thermal desorption directly from the samples for the production of chlorobenzene evolved during pyrolysis of CB. RN, JK and CB samples also contain iron oxides (e.g., hematite, magnetite) [5] which could oxidize organic compounds and catalyze their decomposition [6] leading to differences in the amount and/or nature of pyrolysis products. In order to help interpretation of in situ data obtained by SAM, we study the influence of an iron oxide, hematite, and an oxychlorine phase, Ca-perchlorate, individually, as well as mixed, on alanine, a common amino acid, under conditions simulating the SAM pyrolysis. This work aims to help to determine the influences of key sample minerals on the production of organic compounds detected with SAM in both GC-MS and EGA mode, and to identify potential parent molecules. References: [1] Mahaffy, P. et al. (2012), Space Sci Rev, 170, 401-478. [2] Glavin, D. et al. (2013), JGR. [3] Ming, D. et al. (2013), Science, DOI: 10.1126/science.1245267 [4] Navarro-Gonzalez, R. et al. (2010), JGR. [5] Vaniman, D. T. et al (2013), Science, DOI: 10.1126/science.1243480. 71, 9-17. [6] Iniguez, E. et al. (2009), Geophysical Research Letters, 36. Acknowledgments: SAM-GC team acknowledges support from the French Space Agency (CNES), French National Programme of Planetology (PNP), National French Council (CNRS), Pierre Simon Laplace Institute, Institut Universitaire de France (IUF) and ESEP Labex. J. Eigenbrode and D. Glavin were supported by the NASA MSL participating scientist program.

Evolution of complex higher brain centers and behaviors: behavioral correlates of mushroom body elaboration in insects.

PubMed

Farris, Sarah M

2013-01-01

Large, complex higher brain centers have evolved many times independently within the vertebrates, but the selective pressures driving these acquisitions have been difficult to pinpoint. It is well established that sensory brain centers become larger and more structurally complex to accommodate processing of a particularly important sensory modality. When higher brain centers such as the cerebral cortex become greatly expanded in a particular lineage, it is likely to support the coordination and execution of more complex behaviors, such as those that require flexibility, learning, and social interaction, in response to selective pressures that made these new behaviors advantageous. Vertebrate studies have established a link between complex behaviors, particularly those associated with sociality, and evolutionary expansions of telencephalic higher brain centers. Enlarged higher brain centers have convergently evolved in groups such as the insects, in which multimodal integration and learning and memory centers called the mushroom bodies have become greatly elaborated in at least four independent lineages. Is it possible that similar selective pressures acting on equivalent behavioral outputs drove the evolution of large higher brain centers in all bilaterians? Sociality has greatly impacted brain evolution in vertebrates such as primates, but it has not been a major driver of higher brain center enlargement in insects. However, feeding behaviors requiring flexibility and learning are associated with large higher brain centers in both phyla. Selection for the ability to support behavioral flexibility appears to be a common thread underlying the evolution of large higher brain centers, but the precise nature of these computations and behaviors may vary. © 2013 S. Karger AG, Basel.

Unlocking the "Black box": internal female genitalia in Sepsidae (Diptera) evolve fast and are species-specific

PubMed Central

2010-01-01

Background The species-specificity of male genitalia has been well documented in many insect groups and sexual selection has been proposed as the evolutionary force driving the often rapid, morphological divergence. The internal female genitalia, in sharp contrast, remain poorly studied. Here, we present the first comparative study of the internal reproductive system of Sepsidae. We test the species-specificity of the female genitalia by comparing recently diverged sister taxa. We also compare the rate of change in female morphological characters with the rate of fast-evolving, molecular and behavioral characters. Results We describe the ectodermal parts of the female reproductive tract for 41 species representing 21 of the 37 described genera and define 19 morphological characters with discontinuous variation found in eight structures that are part of the reproductive tract. Using a well-resolved molecular phylogeny based on 10 genes, we reconstruct the evolution of these characters across the family [120 steps; Consistency Index (CI): 0.41]. Two structures, in particular, evolve faster than the rest. The first is the ventral receptacle, which is a secondary sperm storage organ. It accounts for more than half of all the evolutionary changes observed (7 characters; 61 steps; CI: 0.46). It is morphologically diverse across genera, can be bi-lobed or multi-chambered (up to 80 chambers), and is strongly sclerotized in one clade. The second structure is the dorsal sclerite, which is present in all sepsids except Orygma luctuosum and Ortalischema albitarse. It is associated with the opening of the spermathecal ducts and is often distinct even among sister species (4 characters; 16 steps; CI: 0.56). Conclusions We find the internal female genitalia are diverse in Sepsidae and diagnostic for all species. In particular, fast-evolving structures like the ventral receptacle and dorsal sclerite are likely involved in post-copulatory sexual selection. In comparison to behavioral and molecular data, the female structures are evolving 2/3 as fast as the non-constant third positions of the COI barcoding gene. They display less convergent evolution in characters (CI = 0.54) than the third positions or sepsid mating behavior (CICOI = 0.36; CIBEHAV = 0.45). PMID:20831809

Emissions measurements from vegetation fires: A comparative evaluation of methods and results

Treesearch

D. E. Ward; L. F. Radke

1993-01-01

Fires in the open environment produce a diversity of combustion products. Special techniques are needed to characterize the emissions ranging from microcombustion-evolved gas analysis to airborne monitoring of the full-scale phenomenon. This chapter discusses the advantages and disadvantages of each, the use of data in models for full-scale fires, and provides a...

Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

PubMed

Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

2018-01-24

Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

On the evolution of harming and recognition in finite panmictic and infinite structured populations

PubMed Central

Lehmann, Laurent; Feldman, Marcus W.; Rousset, François

2010-01-01

Natural selection may favor two very different types of social behaviors that have costs in vital rates (fecundity and/or survival) to the actor: helping behaviors, which increase the vital rates of recipients, and harming behaviors, which reduce the vital rates of recipients. While social evolutionary theory has mainly dealt with helping behaviors, competition for limited resources creates ecological conditions where an actor may benefit from expressing behaviors that reduce the vital rates of neighbours. This may occur if the reduction in vital rates decreases the intensity of competition experienced by the actor or that experienced by its offspring. Here, we explore the joint evolution of neutral recognition markers and marker-based costly conditional harming whereby actors express harming, conditional on actor and recipient bearing different conspicuous markers. We do so for two complementary demographic scenarios: finite panmictic and infinite structured populations. We find that marker-based conditional harming can evolve under a large range of recombination rates and group sizes under both finite panmictic and infinite structured populations. Direct comparison with results for the evolution of marker-based conditional helping reveals that, if everything else is equal, marker-based conditional harming is often more likely to evolve than marker-based conditional. PMID:19624725

Evolving Self-Organized Behavior for Homogeneous and Heterogeneous UAV or UCAV Swarms

DTIC Science & Technology

2006-03-01

of sensed UAVs and a simple target associated pheromone . At its core, the sets of behaviors are built upon behavior rules describing formation...search randomly around the nest, dropping pheromones for communication. When an ant locates food and returns to the hive, it leaves a trail of... pheromones between the hive and the food-source. When other ants are exposed to the pheromone signal released by the first ant, they have a greater

Effect of pairwise additivity on finite-temperature behavior of classical ideal gas

NASA Astrophysics Data System (ADS)

Shekaari, Ashkan; Jafari, Mahmoud

2018-05-01

Finite-temperature molecular dynamics simulations have been applied to inquire into the effect of pairwise additivity on the behavior of classical ideal gas within the temperature range of T = 250-4000 K via applying a variety of pair potentials and then examining the temperature dependence of a number of thermodynamical properties. Examining the compressibility factor reveals the most deviation from ideal-gas behavior for the Lennard-Jones system mainly due to the presence of both the attractive and repulsive terms. The systems with either attractive or repulsive intermolecular potentials are found to present no resemblance to real gases, but the most similarity to the ideal one as temperature rises.

The Dynamical Classification of Centaurs which Evolve into Comets

NASA Astrophysics Data System (ADS)

Wood, Jeremy R.; Horner, Jonathan; Hinse, Tobias; Marsden, Stephen; Swinburne University of Technology

2016-10-01

Centaurs are small Solar system bodies with semi-major axes between Jupiter and Neptune and perihelia beyond Jupiter. Centaurs can be further subclassified into two dynamical categories - random walk and resonance hopping. Random walk Centaurs have mean square semi-major axes (< a2 >) which vary in time according to a generalized diffusion equation where < a2 > ~t2H. H is the Hurst exponent with 0 < H < 1, and t is time. The behavior of < a2 > for resonance hopping Centaurs is not well described by generalized diffusion.The aim of this study is to determine which dynamical type of Centaur is most likely to evolve into each class of comet. 31,722 fictional massless test particles were integrated for 3 Myr in the 6-body problem (Sun, Jovian planets, test particle). Initially each test particle was a member of one of four groups. The semi-major axes of all test particles in a group were clustered within 0.27 au from a first order, interior Mean Motion resonance of Neptune. The resonances were centered at 18.94 au, 22.95 au, 24.82 au and 28.37 au.If the perihelion of a test particle reached < 4 au then the test particle was considered to be a comet and classified as either a random walk or resonance hopping Centaur. The results showed that over 4,000 test particles evolved into comets within 3 Myr. 59% of these test particles were random walk and 41% were resonance hopping. The behavior of the semi-major axis in time was usually well described by generalized diffusion for random walk Centaurs (ravg = 0.98) and poorly described for resonance hopping Centaurs (ravg = 0.52). The average Hurst exponent was 0.48 for random walk Centaurs and 0.20 for resonance hopping Centaurs. Random walk Centaurs were more likely to evolve into short period comets while resonance hopping Centaurs were more likely to evolve into long period comets. For each initial cluster, resonance hopping Centaurs took longer to evolve into comets than random walk Centaurs. Overall the population of random walk Centaurs averaged 143 kyr to evolve into comets, and the population of resonance hopping Centaurs averaged 164 kyr.

Atmosphere Behavior in Gas-Closed Mouse-Algal Systems: An Experimental and Modelling Study

NASA Technical Reports Server (NTRS)

Averner, M. M.; Moore, B., III; Bartholomew, I.; Wharton, R.

1985-01-01

A dual approach of mathematical modelling and laboratory experimentation aimed at examining the gas exchange characteristics of artificial animal/plant systems closed to the ambient atmosphere was initiated. The development of control techniques and management strategies for maintaining the atmospheric levels of carbon dioxide and oxygen at physiological levels is examined. A mathematical model simulating the atmospheric behavior in these systems was developed and an experimental gas closed system was constructed. These systems are described and preliminary results are presented.

Computational modeling of lava domes using particle dynamics to investigate the effect of conduit flow mechanics on flow patterns

NASA Astrophysics Data System (ADS)

Husain, Taha Murtuza

Large (1--4 x 106 m3) to major (> 4 x 106 m3) dome collapses for andesitic lava domes such as Soufriere Hills Volcano, Montserrat are observed for elevated magma discharge rates (6--13 m3/s). The gas rich magma pulses lead to pressure build up in the lava dome that result in structural failure of the over steepened canyon-like walls which may lead to rockfall or pyroclastic flow. This indicates that dome collapse intimately related to magma extrusion rate. Variation in magma extrusion rate for open-system magma chambers is observed to follow alternating periods of high and low activity. Periodic behavior of magma exhibits a rich diversity in the nature of its eruptive history due to variation in magma chamber size, total crystal content, linear crystal growth rate and magma replenishment rate. Distinguished patterns of growth were observed at different magma flow rates ranging from endogenous to exogenous dome growth for magma with varying strengths. Determining the key parameters that control the transition in flow pattern of the magma during its lava dome building eruption is the main focus. This dissertation examines the mechanical effects on the morphology of the evolving lava dome on the extrusion of magma from a central vent using a 2D particle dynamics model. The particle dynamics model is coupled with a conduit flow model that incorporates the kinetics of crystallization and rheological stiffening to investigate important mechanisms during lava dome building eruptions. Chapter I of this dissertation explores lava dome growth and failure mechanics using a two-dimensional particle-dynamics model. The model follows the evolution of fractured lava, with solidification driven by degassing induced crystallization of magma. The particle-dynamics model emulates the natural development of dome growth and rearrangement of the lava dome which is difficult in mesh-based analyses due to mesh entanglement effects. The deformable talus evolves naturally as a frictional carapace that caps a ductile magma core. Extrusion rate and magma rheology together with crystallization temperature and volatile content govern the distribution of strength in the composite structure. This new model is calibrated against existing observational models of lava dome growth. Chapter II of this dissertation explores the effects of a spectrum of different rheological regimes, on eruptive style and morphologic evolution of lava domes, using a two-dimensional (2D) particle-dynamics model for a spreading viscoplastic (Bingham) fluid. We assume that the ductile magma core of a 2-D synthetic lava dome develops finite yield strength, and that deformable frictional talus evolves from a carapace that caps the magma core. Our new model is calibrated against an existing analytical model for a spreading viscoplastic lava dome and is further compared against observational data of lava dome growth. Chapter III of this dissertation explores different lava-dome styles by developing a two-dimensional particle-dynamics model. These growth patterns range from endogenous lava dome growth comprising expansion of a ductile dome core to the exogenous extrusion of a degassed lava plug resulting in generation of a lava spine. We couple conduit flow dynamics with surface growth of the evolving lava dome, fueled by an open-system magma chamber undergoing continuous replenishment. The conduit flow model accounts for the variation in rheology of ascending magma that results from degassing-induced crystallization. Chapter IV of this dissertation explores the Variation in the extruding lava flow patterns range from endogenous dome growth with a ductile core to the exogenous extrusion of a degassed lava plug that results in the generation of a spine. The variations are a manifestation of the changes in the magma rheology which is governed by magma composition and rate of decompression of the ascending magma. We simulate using a two-dimensional particle-dynamics model, the cyclic behavior of lava dome growth with endogenous growth at high discharge rates followed by exogenous extrusion of rheologically stiffened lava due to degassing induced crystallization at low discharge rates. We couple conduit flow dynamics with surface growth of the evolving lava dome which is fueled by an overpressured reservoir undergoing constant replenishment. The periodic behavior between magma chamber pressure and discharge rate is reproduced as a result of the temporal and spatial change in magma viscosity controlled by crystallization kinetics. Dimensionless numbers are used to map the flow behaviors with the changing extrusion regime. A dimensionless plot identifying the flow transition region during the growth cycle of an evolving lava dome in its lava dome eruptive period is presented. The plot provides a the threshold value of a dimensionless strength parameter (pi 2 < 3.31 x 10-4) below which the transition in flow pattern occurs from endogenously evolving lava dome with a ductile core to the development of a shear lobe for short or long lived periodic episode of the extrusion of magma. (Abstract shortened by UMI.).

Neutral ISM, Ly α , and Lyman-continuum in the Nearby Starburst Haro 11

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivera-Thorsen, T. Emil; Östlin, Göran; Hayes, Matthew

2017-03-01

Star-forming galaxies are believed to be a major source of Lyman continuum (LyC) radiation responsible for reionizing the early universe. Direct observations of escaping ionizing radiation have however been sparse and with low escape fractions. In the local universe, only 10 emitters have been observed, with typical escape fractions of a few percent. The mechanisms regulating this escape need to be strongly evolving with redshift in order to account for the epoch of reionization. Gas content and star formation feedback are among the main suspects, known to both regulate neutral gas coverage and evolve with cosmic time. In this paper,more » we reanalyze Hubble Space Telescope ( HST )-Cosmic Origins Spectrograph (COS) spectrocopy of the first detected local LyC leaker, Haro 11. We examine the connection between LyC leakage and Ly α line shape, and feedback-influenced neutral interstellar medium (ISM) properties like kinematics and gas distribution. We discuss the two extremes of an optically thin, density bounded ISM and a riddled, optically thick, ionization bounded ISM, and how Haro 11 fits into theoretical predictions. We find that the most likely ISM model is a clumpy neutral medium embedded in a highly ionized medium with a combined covering fraction of unity and a residual neutral gas column density in the ionized medium high enough to be optically thick to Ly α , but low enough to be at least partly transparent to LyC and undetected in Si ii. This suggests that star formation feedback and galaxy-scale interaction events play a major role in opening passageways for ionizing radiation through the neutral medium.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thilker, David A.; Bianchi, Luciana; Schiminovich, David

We have discovered recent star formation in the outermost portion ((1-4) x R {sub 25}) of the nearby lenticular (S0) galaxy NGC 404 using Galaxy Evolution Explorer UV imaging. FUV-bright sources are strongly concentrated within the galaxy's H I ring (formed by a merger event according to del RIo et al.), even though the average gas density is dynamically subcritical. Archival Hubble Space Telescope imaging reveals resolved upper main-sequence stars and conclusively demonstrates that the UV light originates from recent star formation activity. We present FUV, NUV radial surface brightness profiles, and integrated magnitudes for NGC 404. Within the ring,more » the average star formation rate (SFR) surface density ({Sigma}{sub SFR}) is {approx}2.2 x 10{sup -5} M {sub sun} yr{sup -1} kpc{sup -2}. Of the total FUV flux, 70% comes from the H I ring which is forming stars at a rate of 2.5 x 10{sup -3} M {sub sun} yr{sup -1}. The gas consumption timescale, assuming a constant SFR and no gas recycling, is several times the age of the universe. In the context of the UV-optical galaxy color-magnitude diagram, the presence of the star-forming H I ring places NGC 404 in the green valley separating the red and blue sequences. The rejuvenated lenticular galaxy has experienced a merger-induced, disk-building excursion away from the red sequence toward bluer colors, where it may evolve quiescently or (if appropriately triggered) experience a burst capable of placing it on the blue/star-forming sequence for up to {approx}1 Gyr. The green valley galaxy population is heterogeneous, with most systems transitioning from blue to red but others evolving in the opposite sense due to acquisition of fresh gas through various channels.« less

Analysis and quantitation of volatile organic compounds emitted from plastics used in museum construction by evolved gas analysis-gas chromatography-mass spectrometry.

PubMed

Samide, Michael J; Smith, Gregory D

2015-12-24

Construction materials used in museums for the display, storage, and transportation of artwork must be assessed for their tendency to emit harmful pollution that could potentially damage cultural treasures. Traditionally, a subjective metals corrosion test known as the Oddy test has been widely utilized in museums for this purpose. To augment the Oddy test, an instrumental sampling approach based on evolved gas analysis (EGA) coupled to gas chromatography (GC) with mass spectral (MS) detection has been implemented for the first time to qualitatively identify off-gassed pollutants under specific conditions. This approach is compared to other instrumental methods reported in the literature. This novel application of the EGA sampling technique yields several benefits over traditional testing, including rapidity, high sensitivity, and broad detectability of volatile organic compounds (VOCs). Furthermore, unlike other reported instrumental approaches, the EGA method was used to determine quantitatively the amount of VOCs emitted by acetate resins and polyurethane foams under specific conditions using both an external calibration method as well as surrogate response factors. EGA was successfully employed to rapidly characterize emissions from 12 types of common plastics. This analysis is advocated as a rapid pre-screening method to rule out poorly performing materials prior to investing time and energy in Oddy testing. The approach is also useful for rapid, routine testing of construction materials previously vetted by traditional testing, but which may experience detrimental formulation changes over time. As an example, a case study on batch re-orders of rigid expanded poly(vinyl chloride) board stock is presented. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of the carrier gas flow rate on the microstructure evolution and the generation of the charged nanoparticles during silicon chemical vapor deposition.

PubMed

Youn, Woong-Kyu; Kim, Chan-Soo; Hwang, Nong-Moon

2013-10-01

The generation of charged nanoparticles in the gas phase has been continually reported in many chemical vapor deposition processes. Charged silicon nanoparticles in the gas phase were measured using a differential mobility analyzer connected to an atmospheric-pressure chemical vapor deposition reactor at various nitrogen carrier gas flow rates (300-1000 standard cubic centimeter per minute) under typical conditions for silicon deposition at the reactor temperature of 900 degrees C. The carrier gas flow rate affected not only the growth behavior of nanostructures but also the number concentration and size distribution of both negatively and positively charged nanoparticles. As the carrier gas flow rate decreased, the growth behavior changed from films to nanowires, which grew without catalytic metal nanoparticles on a quartz substrate.

Similarity and Difference in the Behavior of Gases: An Interactive Demonstration

ERIC Educational Resources Information Center

Ashkenazi, Guy

2008-01-01

Previous research has documented a gap in students' understanding of gas behavior between the algorithmic-macroscopic level and the conceptual-microscopic level. A coherent understanding of both levels is needed to appreciate the difference in properties of different gases, which is not manifest in the ideal gas law. A demonstration that…

Saving the injured: Rescue behavior in the termite-hunting ant Megaponera analis.

PubMed

Frank, Erik Thomas; Schmitt, Thomas; Hovestadt, Thomas; Mitesser, Oliver; Stiegler, Jonas; Linsenmair, Karl Eduard

2017-04-01

Predators of highly defensive prey likely develop cost-reducing adaptations. The ant Megaponera analis is a specialized termite predator, solely raiding termites of the subfamily Macrotermitinae (in this study, mostly colonies of Pseudocanthotermes sp.) at their foraging sites. The evolutionary arms race between termites and ants led to various defensive mechanisms in termites (for example, a caste specialized in fighting predators). Because M. analis incurs high injury/mortality risks when preying on termites, some risk-mitigating adaptations seem likely to have evolved. We show that a unique rescue behavior in M. analis , consisting of injured nestmates being carried back to the nest, reduces combat mortality. After a fight, injured ants are carried back by their nestmates; these ants have usually lost an extremity or have termites clinging to them and are able to recover within the nest. Injured ants that are forced experimentally to return without help, die in 32% of the cases. Behavioral experiments show that two compounds, dimethyl disulfide and dimethyl trisulfide, present in the mandibular gland reservoirs, trigger the rescue behavior. A model accounting for this rescue behavior identifies the drivers favoring its evolution and estimates that rescuing enables maintenance of a 28.7% larger colony size. Our results are the first to explore experimentally the adaptive value of this form of rescue behavior focused on injured nestmates in social insects and help us to identify evolutionary drivers responsible for this type of behavior to evolve in animals.

Debris-carrying camouflage among diverse lineages of Cretaceous insects.

PubMed

Wang, Bo; Xia, Fangyuan; Engel, Michael S; Perrichot, Vincent; Shi, Gongle; Zhang, Haichun; Chen, Jun; Jarzembowski, Edmund A; Wappler, Torsten; Rust, Jes

2016-06-01

Insects have evolved diverse methods of camouflage that have played an important role in their evolutionary success. Debris-carrying, a behavior of actively harvesting and carrying exogenous materials, is among the most fascinating and complex behaviors because it requires not only an ability to recognize, collect, and carry materials but also evolutionary adaptations in related morphological characteristics. However, the fossil record of such behavior is extremely scarce, and only a single Mesozoic example from Spanish amber has been recorded; therefore, little is known about the early evolution of this complicated behavior and its underlying anatomy. We report a diverse insect assemblage of exceptionally preserved debris carriers from Cretaceous Burmese, French, and Lebanese ambers, including the earliest known chrysopoid larvae (green lacewings), myrmeleontoid larvae (split-footed lacewings and owlflies), and reduviids (assassin bugs). These ancient insects used a variety of debris material, including insect exoskeletons, sand grains, soil dust, leaf trichomes of gleicheniacean ferns, wood fibers, and other vegetal debris. They convergently evolved their debris-carrying behavior through multiple pathways, which expressed a high degree of evolutionary plasticity. We demonstrate that the behavioral repertoire, which is associated with considerable morphological adaptations, was already widespread among insects by at least the Mid-Cretaceous. Together with the previously known Spanish specimen, these fossils are the oldest direct evidence of camouflaging behavior in the fossil record. Our findings provide a novel insight into early evolution of camouflage in insects and ancient ecological associations among plants and insects.

Saving the injured: Rescue behavior in the termite-hunting ant Megaponera analis

PubMed Central

Frank, Erik Thomas; Schmitt, Thomas; Hovestadt, Thomas; Mitesser, Oliver; Stiegler, Jonas; Linsenmair, Karl Eduard

2017-01-01

Predators of highly defensive prey likely develop cost-reducing adaptations. The ant Megaponera analis is a specialized termite predator, solely raiding termites of the subfamily Macrotermitinae (in this study, mostly colonies of Pseudocanthotermes sp.) at their foraging sites. The evolutionary arms race between termites and ants led to various defensive mechanisms in termites (for example, a caste specialized in fighting predators). Because M. analis incurs high injury/mortality risks when preying on termites, some risk-mitigating adaptations seem likely to have evolved. We show that a unique rescue behavior in M. analis, consisting of injured nestmates being carried back to the nest, reduces combat mortality. After a fight, injured ants are carried back by their nestmates; these ants have usually lost an extremity or have termites clinging to them and are able to recover within the nest. Injured ants that are forced experimentally to return without help, die in 32% of the cases. Behavioral experiments show that two compounds, dimethyl disulfide and dimethyl trisulfide, present in the mandibular gland reservoirs, trigger the rescue behavior. A model accounting for this rescue behavior identifies the drivers favoring its evolution and estimates that rescuing enables maintenance of a 28.7% larger colony size. Our results are the first to explore experimentally the adaptive value of this form of rescue behavior focused on injured nestmates in social insects and help us to identify evolutionary drivers responsible for this type of behavior to evolve in animals. PMID:28439543

Atmosphere behavior in gas-closed mouse-algal systems - An experimental and modelling study

NASA Technical Reports Server (NTRS)

Averner, M. M.; Moore, B., III; Bartholomew, I.; Wharton, R.

1984-01-01

A NASA-sponsored research program initiated using mathematical modelling and laboratory experimentation aimed at examining the gas-exchange characteristics of artificial animal/plant systems closed to the ambient atmosphere is studied. The development of control techniques and management strategies for maintaining the atmospheric levels of carbon dioxide and oxygen at physiological levels is considered. A mathematical model simulating the behavior of a gas-closed mouse-algal system under varying environmental conditions is described. To verify and validate the model simulations, an analytical system with which algal growth and gas exchange characteristics can be manipulated and measured is designed, fabricated, and tested. The preliminary results are presented.

Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

NASA Astrophysics Data System (ADS)

Wu, Jie; Huang, Jun-Jie

2015-07-01

Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

Variables, Decisions, and Scripting in Construct

DTIC Science & Technology

2009-09-01

grounded in sociology and cognitive science which seeks to model the processes and situations by which humans interact and share information...Construct is an embodiment of constructuralism (Carley 1986), a theory which posits that human social structures and cognitive structures co-evolve so that...human cognition reflects human social behavior, and that human social behavior simultaneously influences cognitive processes. Recent work with

Extraction of hot QCD matter transport coefficients utilizing microscopic transport theory

NASA Astrophysics Data System (ADS)

Demir, Nasser Soliman

Ultrarelativistic heavy-ion collisions at the Relativistic Heavy-Ion Collider (RHIC) are thought to have produced a state of matter called the Quark-Gluon-Plasma (QGP). The QGP forms when nuclear matter governed by Quantum Chromodynamics (QCD) reaches a temperature and baryochemical potential necessary to achieve the transition of hadrons (bound states of quarks and gluons) to deconfined quarks and gluons. Such conditions have been achieved at RHIC, and the resulting QGP created exhibits properties of a near perfect fluid. In particular, strong evidence shows that the QGP exhibits a very small shear viscosity to entropy density ratio eta/s, near the lower bound predicted for that quantity by Anti-deSitter space/Conformal Field Theory (AdS/CFT) methods of eta/s = ℎ4pkB , where h is Planck's constant and kB is Boltzmann's constant. As the produced matter expands and cools, it evolves through a phase described by a hadron gas with rapidly increasing eta/s. This thesis presents robust calculations of eta/s for hadronic and partonic media as a function of temperature using the Green-Kubo formalism. An analysis is performed for the behavior of eta/s to mimic situations of the hadronic media at RHIC evolving out of chemical equilibrium, and systematic uncertainties are assessed for our method. In addition, preliminary results are presented for the bulk viscosity to entropy density ratio zeta/s, whose behavior is not well-known in a relativistic heavy ion collisions. The diffusion coefficient for baryon number is investigated, and an algorithm is presented to improve upon the previous work of investigation of heavy quark diffusion in a thermal QGP. By combining the results of my investigations for eta/s from our microscopic transport models with what is currently known from the experimental results on elliptic flow from RHIC, I find that the trajectory of eta/s in a heavy ion collision has a rich structure, especially near the deconfinement transition temperature Tc. I have helped quantify the viscous hadronic effects to enable investigators to constrain the value of eta/s for the QGP created at RHIC.

Rational Constraints and the Evolution of Fairness in the Ultimatum Game.

PubMed

Tomlin, Damon

2015-01-01

Behavior in the Ultimatum Game has been well-studied experimentally, and provides a marked contrast between the theoretical model of a self-interested economic agent and that of an actual human concerned with social norms such as fairness. How did such norms evolve, when punishing unfair behavior can be costly to the punishing agent? The work described here simulated a series of Ultimatum Games, in which populations of agents earned resources based on their preferences for proposing and accepting (or rejecting) offers of various sizes. Two different systems governing the acceptance or rejection of offers were implemented. Under one system, the probability that an agent accepted an offer of a given size was independent of the probabilities of accepting the other possible offers. Under the other system, a simple, ordinal constraint was placed on the acceptance probabilities such that a given offer was at least as likely to be accepted as a smaller offer. For simulations under either system, agents' preferences and their corresponding behavior evolved over multiple generations. Populations without the ordinal constraint came to emulate maximizing economic agents, while populations with the constraint came to resemble the behavior of human players.

A diffusion perspective on temporal networks: A case study on a supermarket

NASA Astrophysics Data System (ADS)

Deng, Shiguo; Qiu, Lu; Yang, Yue; Yang, Huijie

2016-01-01

From a large amount of records, one can extract behavioral characteristics of a social system at different scales. Theoretically, it can help us to know how the global behavior of a social system is formed from individual activities. Practically, it can be used to optimize and even to control the social system. Complicated relationships between the individuals form a network, which evolves with time. The behavior of the system can be accordingly understood in the framework of temporal network. In the present paper, instead of focusing on microscopic structures, we develop a framework to investigate temporal networks from the viewpoint of diffusion process, in which each snapshot network is divided into groups and the ID number of the group a node belongs to is used to measure its state. By this way trajectories of the nodes form an ensemble of realizations of a stochastic process. As an illustration, we investigate the diffusion behavior of a supermarket. One can find that with the increase of time the customers cluster and separate into different groups. Meanwhile, the system evolves in a significant order way, instead of a complete random one.

Evolution of Signaling in a Multi-Robot System: Categorization and Communication

NASA Astrophysics Data System (ADS)

Ampatzis, Christos; Tuci, Elio; Trianni, Vito; Dorigo, Marco

We use Evolutionary Robotics to design robot controllers in which decision-making mechanisms to switch from solitary to social behavior are integrated with the mechanisms that underpin the sensory-motor repertoire of the robots. In particular, we study the evolution of behavioral and communicative skills in a categorization task. The individual decision-making structures are based on the integration over time of sensory information. The mechanisms for switching from solitary to social behavior and the ways in which the robots can affect each other's behavior are not predetermined by the experimenter, but are aspects of our model designed by artificial evolution. Our results show that evolved robots manage to cooperate and collectively discriminate between different environments by developing a simple communication protocol based on sound signaling. Communication emerges in the absence of explicit selective pressure coded in the fitness function. The evolution of communication is neither trivial nor obvious; for a meaningful signaling system to evolve, evolution must produce both appropriate signals and appropriate reactions to signals. The use of communication proves to be adaptive for the group, even if, in principle, non-cooperating robots can be equally successful with cooperating robots.

Ecological Relationships Between Components in Closed Aquatic Ecosystems

NASA Astrophysics Data System (ADS)

Pisman, Tamara; Somova, Lydia

The work considers the problems of relationships between algae and other microorganisms in aquatic ecosystems. Using small-scale laboratory "autotroph-heterotroph" ecosystems with different types of closure, we showed the results of the investigation into the ecological relation-ships of algae in biocenoses. The autotrophic component was represented by green microalgae, and the heterotrophic component -by yeast and bacteria. An important role in functioning of algobacterial communities is played by 2 -2 (oxygen -carbon dioxide) exchange. The gas exchange between algae and yeast was studied in the "autotroph-heterotroph" gas-closed ecosystem with space-divided components. It was shown that the gas exchange closure of the components into a system prolongs its existence. Hav-ing increased the degree of the system closure by introducing two yeast species with positive metabolic interaction to the heterotrophic component, we observed a significant increase in the gas exchange between the components and thus in the biomass of algae and yeast. The most ancient and ecologically relevant symbioses known in nature are symbiotic associa-tions of algae and heterotrophic organisms. The main symbionts of algae in aquatic ecosystems are bacteria. The cenosis-forming role of algae is based on two characteristics: firstly, their mucous covers and membranes are able to absorb and retain large amounts of water; secondly, many algae evolve various organic substances during their lifetime. An example of algobacterial associations are microalgae Chlorella vulgaris and accompanying microbial flora. Experiments with non-sterile batch culture of algae showed that the increase in the algae biomass was accompanied by the increase in the bacterial biomass. As a result of theoretical and experi-mental investigation into their relationships, it was shown that the largest biomass of bacteria is achieved when using organic substances evolved by algae and having bacteria grow on dead algae; i.e. bacteria can also act as decomposers. It was demonstrated that the cenosis-forming role of algae and bacteria in an algobacterial cenosis is determined by accumulation of both organic matter and nitrogen which is included into the cycle of matter. Thus, the process of C-compound evolution by algae in an algobacterial cenosis is strongly connected with the process of consumption of these compounds by corresponding bacteria, which, in their turn, ensure photosynthesis and algae development by evolving 2 and nitrogen.

Evolution of Self-Organized Task Specialization in Robot Swarms

PubMed Central

Ferrante, Eliseo; Turgut, Ali Emre; Duéñez-Guzmán, Edgar; Dorigo, Marco; Wenseleers, Tom

2015-01-01

Division of labor is ubiquitous in biological systems, as evidenced by various forms of complex task specialization observed in both animal societies and multicellular organisms. Although clearly adaptive, the way in which division of labor first evolved remains enigmatic, as it requires the simultaneous co-occurrence of several complex traits to achieve the required degree of coordination. Recently, evolutionary swarm robotics has emerged as an excellent test bed to study the evolution of coordinated group-level behavior. Here we use this framework for the first time to study the evolutionary origin of behavioral task specialization among groups of identical robots. The scenario we study involves an advanced form of division of labor, common in insect societies and known as “task partitioning”, whereby two sets of tasks have to be carried out in sequence by different individuals. Our results show that task partitioning is favored whenever the environment has features that, when exploited, reduce switching costs and increase the net efficiency of the group, and that an optimal mix of task specialists is achieved most readily when the behavioral repertoires aimed at carrying out the different subtasks are available as pre-adapted building blocks. Nevertheless, we also show for the first time that self-organized task specialization could be evolved entirely from scratch, starting only from basic, low-level behavioral primitives, using a nature-inspired evolutionary method known as Grammatical Evolution. Remarkably, division of labor was achieved merely by selecting on overall group performance, and without providing any prior information on how the global object retrieval task was best divided into smaller subtasks. We discuss the potential of our method for engineering adaptively behaving robot swarms and interpret our results in relation to the likely path that nature took to evolve complex sociality and task specialization. PMID:26247819

Evolution of Self-Organized Task Specialization in Robot Swarms.

PubMed

Ferrante, Eliseo; Turgut, Ali Emre; Duéñez-Guzmán, Edgar; Dorigo, Marco; Wenseleers, Tom

2015-08-01

Division of labor is ubiquitous in biological systems, as evidenced by various forms of complex task specialization observed in both animal societies and multicellular organisms. Although clearly adaptive, the way in which division of labor first evolved remains enigmatic, as it requires the simultaneous co-occurrence of several complex traits to achieve the required degree of coordination. Recently, evolutionary swarm robotics has emerged as an excellent test bed to study the evolution of coordinated group-level behavior. Here we use this framework for the first time to study the evolutionary origin of behavioral task specialization among groups of identical robots. The scenario we study involves an advanced form of division of labor, common in insect societies and known as "task partitioning", whereby two sets of tasks have to be carried out in sequence by different individuals. Our results show that task partitioning is favored whenever the environment has features that, when exploited, reduce switching costs and increase the net efficiency of the group, and that an optimal mix of task specialists is achieved most readily when the behavioral repertoires aimed at carrying out the different subtasks are available as pre-adapted building blocks. Nevertheless, we also show for the first time that self-organized task specialization could be evolved entirely from scratch, starting only from basic, low-level behavioral primitives, using a nature-inspired evolutionary method known as Grammatical Evolution. Remarkably, division of labor was achieved merely by selecting on overall group performance, and without providing any prior information on how the global object retrieval task was best divided into smaller subtasks. We discuss the potential of our method for engineering adaptively behaving robot swarms and interpret our results in relation to the likely path that nature took to evolve complex sociality and task specialization.

Constraints on the Mineralogy of Gale Crater Mudstones from MSL SAM Evolved Water

NASA Technical Reports Server (NTRS)

McAdam, A. C.; Sutter, B.; Franz, H. B.; Hogancamp, J. V. (Clark); Knudson, C. A.; Andrejkovicova, S.; Archer, P. D.; Eigenbrode, J. L.; Ming, D. W.; Mahaffy, P. R.

2017-01-01

The Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments on the Mars Science Laboratory (MSL) have analysed more than 150 micron fines from 14 sites at Gale Crater. Here we focus on the mudstone samples. Two were drilled from sites John Klein (JK) and Cumberland (CB) in the Sheepbed mudstone. Six were drilled from Murray Formation mudstone: Confidence Hills (CH), Mojave (MJ), Telegraph Peak (TP), Buckskin (BK), Oudam (OU), Marimba (MB). SAM's evolved gas analysis mass spectrometry (EGA-MS) detected H2O, CO2, O2, H2, SO2, H2S, HCl, NO, and other trace gases, including organic fragments. The identity and evolution temperature of evolved gases can support CheMin mineral detection and place constraints on trace volatile-bearing phases or phases difficult to characterize with X-ray diffraction (e.g., amorphous phases). Here we will focus on SAM H2O data and comparisons to SAM-like analyses of key reference materials.

A Raman spectroscopic study of thermally treated glushinskite--the natural magnesium oxalate dihydrate.

PubMed

Frost, Ray L; Adebajo, Moses; Weier, Matt L

2004-02-01

Raman spectroscopy has been used to study the thermal transformations of natural magnesium oxalate dihydrate known in mineralogy as glushinskite. The data obtained by Raman spectroscopy was supplemented with that of infrared emission spectroscopy. The vibrational spectroscopic data was complimented with high resolution thermogravimetric analysis combined with evolved gas mass spectrometry. TG-MS identified two mass loss steps at 146 and 397 degrees C. In the first mass loss step water is evolved only, in the second step carbon dioxide is evolved. The combination of Raman microscopy and a thermal stage clearly identifies the changes in the molecular structure with thermal treatment. Glushinskite is the dihydrate phase in the temperature range up to the pre-dehydration temperature of 146 degrees C. Above 397 degrees C, magnesium oxide is formed. Infrared emission spectroscopy shows that this mineral decomposes at around 400 degrees C. Changes in the position and intensity of the CO and CC stretching vibrations in the Raman spectra indicate the temperature range at which these phase changes occur.

From cues to signals: evolution of interspecific communication via aposematism and mimicry in a predator-prey system.

PubMed

Lehmann, Kenna D S; Goldman, Brian W; Dworkin, Ian; Bryson, David M; Wagner, Aaron P

2014-01-01

Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment.

Towards Evolving Electronic Circuits for Autonomous Space Applications

NASA Technical Reports Server (NTRS)

Lohn, Jason D.; Haith, Gary L.; Colombano, Silvano P.; Stassinopoulos, Dimitris

2000-01-01

The relatively new field of Evolvable Hardware studies how simulated evolution can reconfigure, adapt, and design hardware structures in an automated manner. Space applications, especially those requiring autonomy, are potential beneficiaries of evolvable hardware. For example, robotic drilling from a mobile platform requires high-bandwidth controller circuits that are difficult to design. In this paper, we present automated design techniques based on evolutionary search that could potentially be used in such applications. First, we present a method of automatically generating analog circuit designs using evolutionary search and a circuit construction language. Our system allows circuit size (number of devices), circuit topology, and device values to be evolved. Using a parallel genetic algorithm, we present experimental results for five design tasks. Second, we investigate the use of coevolution in automated circuit design. We examine fitness evaluation by comparing the effectiveness of four fitness schedules. The results indicate that solution quality is highest with static and co-evolving fitness schedules as compared to the other two dynamic schedules. We discuss these results and offer two possible explanations for the observed behavior: retention of useful information, and alignment of problem difficulty with circuit proficiency.

From Cues to Signals: Evolution of Interspecific Communication via Aposematism and Mimicry in a Predator-Prey System

PubMed Central

Lehmann, Kenna D. S.; Goldman, Brian W.; Dworkin, Ian; Bryson, David M.; Wagner, Aaron P.

2014-01-01

Current theory suggests that many signaling systems evolved from preexisting cues. In aposematic systems, prey warning signals benefit both predator and prey. When the signal is highly beneficial, a third species often evolves to mimic the toxic species, exploiting the signaling system for its own protection. We investigated the evolutionary dynamics of predator cue utilization and prey signaling in a digital predator-prey system in which prey could evolve to alter their appearance to mimic poison-free or poisonous prey. In predators, we observed rapid evolution of cue recognition (i.e. active behavioral responses) when presented with sufficiently poisonous prey. In addition, active signaling (i.e. mimicry) evolved in prey under all conditions that led to cue utilization. Thus we show that despite imperfect and dishonest signaling, given a high cost of consuming poisonous prey, complex systems of interspecific communication can evolve via predator cue recognition and prey signal manipulation. This provides evidence supporting hypotheses that cues may serve as stepping-stones in the evolution of more advanced communication and signaling systems that incorporate information about the environment. PMID:24614755

Extinction events can accelerate evolution.

PubMed

Lehman, Joel; Miikkulainen, Risto

2015-01-01

Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the long term.

Influence of methane emissions and vehicle efficiency on the climate implications of heavy-duty natural gas trucks.

PubMed

Camuzeaux, Jonathan R; Alvarez, Ramón A; Brooks, Susanne A; Browne, Joshua B; Sterner, Thomas

2015-06-02

While natural gas produces lower carbon dioxide emissions than diesel during combustion, if enough methane is emitted across the fuel cycle, then switching a heavy-duty truck fleet from diesel to natural gas can produce net climate damages (more radiative forcing) for decades. Using the Technology Warming Potential methodology, we assess the climate implications of a diesel to natural gas switch in heavy-duty trucks. We consider spark ignition (SI) and high-pressure direct injection (HPDI) natural gas engines and compressed and liquefied natural gas. Given uncertainty surrounding several key assumptions and the potential for technology to evolve, results are evaluated for a range of inputs for well-to-pump natural gas loss rates, vehicle efficiency, and pump-to-wheels (in-use) methane emissions. Using reference case assumptions reflecting currently available data, we find that converting heavy-duty truck fleets leads to damages to the climate for several decades: around 70-90 years for the SI cases, and 50 years for the more efficient HPDI. Our range of results indicates that these fuel switches have the potential to produce climate benefits on all time frames, but combinations of significant well-to-wheels methane emissions reductions and natural gas vehicle efficiency improvements would be required.

Communication: Quantitative Fourier-transform infrared data for competitive loading of small cages during all-vapor instantaneous formation of gas-hydrate aerosols

NASA Astrophysics Data System (ADS)

Uras-Aytemiz, Nevin; Abrrey Monreal, I.; Devlin, J. Paul

2011-10-01

A simple method has been developed for the measurement of high quality FTIR spectra of aerosols of gas-hydrate nanoparticles. The application of this method enables quantitative observation of gas hydrates that form on subsecond timescales using our all-vapor approach that includes an ether catalyst rather than high pressures to promote hydrate formation. The sampling method is versatile allowing routine studies at temperatures ranging from 120 to 210 K of either a single gas or the competitive uptake of different gas molecules in small cages of the hydrates. The present study emphasizes hydrate aerosols formed by pulsing vapor mixtures into a cold chamber held at 160 or 180 K. We emphasize aerosol spectra from 6 scans recorded an average of 8 s after "instantaneous" hydrate formation as well as of the gas hydrates as they evolve with time. Quantitative aerosol data are reported and analyzed for single small-cage guests and for mixed hydrates of CO2, CH4, C2H2, N2O, N2, and air. The approach, combined with the instant formation of gas hydrates from vapors only, offers promise with respect to optimization of methods for the formation and control of gas hydrates.

Evolution of the Interstellar Gas Fraction Over Cosmic Time

NASA Astrophysics Data System (ADS)

Wiklind, Tommy; CANDELS

2018-01-01

Galaxies evolve by transforming gas into stars. The gas is acquired through accretion and mergers and is a highly intricate process where feed-back processes play an important role. Directly measuring the gas content in distant galaxies is, however, both complicated and time consuming. A direct observations involves either observing neutral hydrogen using the 21cm line or observing the molecular gas component using tracer molecules such as CO. The former method is impeded by man-made radio interference, and the latter is time consuming even with sensitive instruments such s ALMA. An indirect method is to observe the Raleigh-Jeans part of the dust SED and from this infer the gas mass. Here we present the results from a project using ALMA to measure the RJ part of the dust SED in a carefully selected sample of 70 galaxies at redshifts z=2-5. The galaxies are selected solely based on their redshift and stellar mass and therefore represents an unbiased sample. The stellar masses are selected using the MEAM method and thus the sample corresponds to progenitors of a z=0 galaxy of a particular stellar mass. Preliminary results show that the average gas fraction increases with redshift over the range z=2-3 in accordance with theoretical models, but at z≥4 the observed gas fraction is lower.

Surfacing behavior and gas release of the physostome sprat (Sprattus sprattus) in ice-free and ice-covered waters.

PubMed

Solberg, Ingrid; Kaartvedt, Stein

2014-01-01

Upward-facing echosounders that provided continuous, long-term measurements were applied to address the surfacing behavior and gas release of the physostome sprat ( Sprattus sprattus ) throughout an entire winter in a 150-m-deep Norwegian fjord. During ice-free conditions, the sprat surfaced and released gas bubbles at night with an estimated surfacing rate of 3.5 times per fish day -1 . The vertical swimming speeds during surfacing were considerably higher (~10 times) than during diel vertical migrations, especially when returning from the surface, and particularly when the fjord was not ice covered. The sprat released gas a few hours after surfacing, suggesting that the sprat gulped atmospheric air during its excursions to the surface. While the surface activity increased after the fjord became ice covered, the records of gas release decreased sharply. The under-ice fish then displayed a behavior interpreted as "searching for the surface" by repeatedly ascending toward the ice, apparently with limited success of filling the swim bladder. This interpretation was supported by lower acoustic target strength in ice-covered waters. The frequent surfacing behavior demonstrated in this study indicates that gulping of atmospheric air is an important element in the life of sprat. While at least part of the population endured overwintering in the ice-covered habitat, ice covering may constrain those physostome fishes that lack a gas-generating gland in ways that remain to be established.

Role of rough surface topography on gas slip flow in microchannels.

PubMed

Zhang, Chengbin; Chen, Yongping; Deng, Zilong; Shi, Mingheng

2012-07-01

We conduct a lattice Boltzmann simulation of gas slip flow in microchannels incorporating rough surface effects as characterized by fractal geometry with a focus on gas-solid interaction. The gas slip flow in rough microchannels, which is characterized by Poiseuille number and mass flow rate, is evaluated and compared with smooth microchannels. The effects of roughness height, surface fractal dimension, and Knudsen number on slip behavior of gas flow in microchannels are all investigated and discussed. The results indicate that the presence of surface roughness reduces boundary slip for gas flow in microchannels with respect to a smooth surface. The gas flows at the valleys of rough walls are no-slip while velocity slips are observed over the top of rough walls. We find that the gas flow behavior in rough microchannels is insensitive to the surface topography irregularity (unlike the liquid flow in rough microchannels) but is influenced by the statistical height of rough surface and rarefaction effects. In particular, decrease in roughness height or increase in Knudsen number can lead to large wall slip for gas flow in microchannels.

Imperfect information facilitates the evolution of reciprocity.

PubMed

Kurokawa, Shun

2016-06-01

The existence of cooperation demands explanation since cooperation is costly to the actor. Reciprocity has long been regarded as a potential explanatory mechanism for the existence of cooperation. Reciprocity is a mechanism wherein a cooperator responds to an opponent's behavior by switching his/her own behavior. Hence, a possible problematic case relevant to the theory of reciprocity evolution arises when the mechanism is such that the information regarding an opponent's behavior is imperfect. Although it has been confirmed also by previous theoretical studies that imperfect information interferes with the evolution of reciprocity, this argument is based on the assumption that there are no mistakes in behavior. And, a previous study presumed that it might be expected that when such mistakes occur, reciprocity can more readily evolve in the case of imperfect information than in the case of perfect information. The reason why the previous study considers so is that in the former case, reciprocators can miss defections incurred by other reciprocators' mistakes due to imperfect information, allowing cooperation to persist when such reciprocators meet. However, contrary to this expectation, the previous study has shown that even when mistakes occur, imperfect information interferes with the evolution of reciprocity. Nevertheless, the previous study assumed that payoffs are linear (i.e., that the effect of behavior is additive and there are no synergetic effects). In this study, we revisited the same problem but removed the assumption that payoffs are linear. We used evolutionarily stable strategy analysis to compare the condition for reciprocity to evolve when mistakes occur and information is imperfect with the condition for reciprocity to evolve when mistakes occur and information is perfect. Our study revealed that when payoffs are not linear, imperfect information can facilitate the evolution of reciprocity when mistakes occur; while when payoffs are linear, imperfect information disturbs the evolution of reciprocity even when mistakes occur. Imperfect information can encourage the evolution of cooperation. Copyright © 2016 Elsevier Inc. All rights reserved.

Thermoregulation in homeothermic and poikilothermic organisms

EPA Science Inventory

Homeothermic organisms (birds and mammals) have evolved autonomic and behavioral thermoeffectors to maintain a relatively constant core temperature over a wide range of environmental temperatures. Poikilotherms, including reptiles, amphibians, fish, and insects have internal temp...

Mating behavior and the evolution of sperm design

PubMed Central

Schärer, Lukas; Littlewood, D. Timothy J.; Waeschenbach, Andrea; Yoshida, Wataru; Vizoso, Dita B.

2011-01-01

Sperm are the most diverse of all animal cell types, and much of the diversity in sperm design is thought to reflect adaptations to the highly variable conditions under which sperm function and compete to achieve fertilization. Recent work has shown that these conditions often evolve rapidly as a consequence of multiple mating, suggesting a role for sexual selection and sexual conflict in the evolution of sperm design. However, very little of the striking diversity in sperm design is understood functionally, particularly in internally fertilizing organisms. We use phylogenetic comparative analyses covering 16 species of the hermaphroditic flatworm genus Macrostomum to show that a complex sperm design is associated with reciprocal mating and that this complexity is lost secondarily when hypodermic insemination—sperm injection through the epidermis—evolves. Specifically, the complex sperm design, which includes stiff lateral bristles, is likely a male persistence trait associated with sexual conflicts over the fate of received ejaculates and linked to female resistance traits, namely an intriguing postcopulatory sucking behavior and a thickened epithelium of the sperm-receiving organ. Our results suggest that the interactions between sperm donor, sperm, and sperm recipient can change drastically when hypodermic insemination evolves, involving convergent evolution of a needle-like copulatory organ, a simpler sperm design, and a simpler female genital morphology. Our study documents that a shift in the mating behavior may alter fundamentally the conditions under which sperm compete and thereby lead to a drastic change in sperm design. PMID:21220334

Deformation behaviors of peat with influence of organic matter.

PubMed

Yang, Min; Liu, Kan

2016-01-01

Peat is a kind of special material rich in organic matter. Because of the high content of organic matter, it shows different deformation behaviors from conventional geotechnical materials. Peat grain has a non-negligible compressibility due to the presence of organic matter. Biogas can generate from peat and can be trapped in form of gas bubbles. Considering the natural properties of peat, a special three-phase composition of peat is described which indicates the existence of organic matter and gas bubbles in peat. A stress-strain-time model is proposed for the compression of organic matter, and the surface tension effect is considered in the compression model of gas bubbles. Finally, a mathematical model has been developed to simulate the deformation behavior of peat considering the compressibility of organic matter and entrapped gas bubbles. The deformation process is the coupling of volume variation of organic matter, gas bubbles and water drainage. The proposed model is used to simulate a series of peat laboratory oedometer tests, and the model can well capture the test results with reasonable model parameters. Effects of model parameters on deformation of peat are also analyzed.

Using artificial neural networks to constrain the halo baryon fraction during reionization

NASA Astrophysics Data System (ADS)

Sullivan, David; Iliev, Ilian T.; Dixon, Keri L.

2018-01-01

Radiative feedback from stars and galaxies has been proposed as a potential solution to many of the tensions with simplistic galaxy formation models based on Λcold dark matter, such as the faint end of the ultraviolet (UV) luminosity function. The total energy budget of radiation could exceed that of galactic winds and supernovae combined, which has driven the development of sophisticated algorithms that evolve both the radiation field and the hydrodynamical response of gas simultaneously, in a cosmological context. We probe self-feedback on galactic scales using the adaptive mesh refinement, radiative transfer, hydrodynamics, and N-body code RAMSES-RT. Unlike previous studies which assume a homogeneous UV background, we self-consistently evolve both the radiation field and gas to constrain the halo baryon fraction during cosmic reionization. We demonstrate that the characteristic halo mass with mean baryon fraction half the cosmic mean, Mc(z), shows very little variation as a function of mass-weighted ionization fraction. Furthermore, we find that the inclusion of metal cooling and the ability to resolve scales small enough for self-shielding to become efficient leads to a significant drop in Mc when compared to recent studies. Finally, we develop an artificial neural network that is capable of predicting the baryon fraction of haloes based on recent tidal interactions, gas temperature, and mass-weighted ionization fraction. Such a model can be applied to any reionization history, and trivially incorporated into semi-analytical models of galaxy formation.

Massive black hole and gas dynamics in galaxy nuclei mergers - I. Numerical implementation

NASA Astrophysics Data System (ADS)

Lupi, Alessandro; Haardt, Francesco; Dotti, Massimo

2015-01-01

Numerical effects are known to plague adaptive mesh refinement (AMR) codes when treating massive particles, e.g. representing massive black holes (MBHs). In an evolving background, they can experience strong, spurious perturbations and then follow unphysical orbits. We study by means of numerical simulations the dynamical evolution of a pair MBHs in the rapidly and violently evolving gaseous and stellar background that follows a galaxy major merger. We confirm that spurious numerical effects alter the MBH orbits in AMR simulations, and show that numerical issues are ultimately due to a drop in the spatial resolution during the simulation, drastically reducing the accuracy in the gravitational force computation. We therefore propose a new refinement criterion suited for massive particles, able to solve in a fast and precise way for their orbits in highly dynamical backgrounds. The new refinement criterion we designed enforces the region around each massive particle to remain at the maximum resolution allowed, independently upon the local gas density. Such maximally resolved regions then follow the MBHs along their orbits, and effectively avoids all spurious effects caused by resolution changes. Our suite of high-resolution, AMR hydrodynamic simulations, including different prescriptions for the sub-grid gas physics, shows that the new refinement implementation has the advantage of not altering the physical evolution of the MBHs, accounting for all the non-trivial physical processes taking place in violent dynamical scenarios, such as the final stages of a galaxy major merger.

Infalling clouds on to supermassive black hole binaries - II. Binary evolution and the final parsec problem

NASA Astrophysics Data System (ADS)

Goicovic, Felipe G.; Sesana, Alberto; Cuadra, Jorge; Stasyszyn, Federico

2017-11-01

The formation of massive black hole binaries (MBHBs) is an unavoidable outcome of galaxy evolution via successive mergers. However, the mechanism that drives their orbital evolution from parsec separations down to the gravitational wave dominated regime is poorly understood, and their final fate is still unclear. If such binaries are embedded in gas-rich and turbulent environments, as observed in remnants of galaxy mergers, the interaction with gas clumps (such as molecular clouds) may efficiently drive their orbital evolution. Using numerical simulations, we test this hypothesis by studying the dynamical evolution of an equal mass, circular MBHB accreting infalling molecular clouds. We investigate different orbital configurations, modelling a total of 13 systems to explore different possible impact parameters and relative inclinations of the cloud-binary encounter. We focus our study on the prompt, transient phase during the first few orbits when the dynamical evolution of the binary is fastest, finding that this evolution is dominated by the exchange of angular momentum through gas capture by the individual black holes and accretion. Building on these results, we construct a simple model for evolving an MBHB interacting with a sequence of clouds, which are randomly drawn from reasonable populations with different levels of anisotropy in their angular momenta distributions. We show that the binary efficiently evolves down to the gravitational wave emission regime within a few hundred million years, overcoming the 'final parsec' problem regardless of the stellar distribution.

Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, Carmen P.; Pierce, David A.; Schweiger, Michael J.

2013-12-03

For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent massmore » loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.« less

DESTRUCTION OF INTERSTELLAR DUST IN EVOLVING SUPERNOVA REMNANT SHOCK WAVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P., E-mail: jslavin@cfa.harvard.edu

2015-04-10

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however, that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al., we adopt the same dust properties as in that paper. We find that the efficiencies of grainmore » destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities ≳200 km s{sup −1} for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of ∼2 compared to those of Jones et al., who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of ∼3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of ∼2–3 Gyr. These increases, while not able to resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step toward understanding the origin and evolution of dust in the ISM.« less

Destruction of Interstellar Dust in Evolving Supernova Remnant Shock Waves

NASA Technical Reports Server (NTRS)

Slavin, Jonathan D.; Dwek, Eli; Jones, Anthony P.

2015-01-01

Supernova generated shock waves are responsible for most of the destruction of dust grains in the interstellar medium (ISM). Calculations of the dust destruction timescale have so far been carried out using plane parallel steady shocks, however that approximation breaks down when the destruction timescale becomes longer than that for the evolution of the supernova remnant (SNR) shock. In this paper we present new calculations of grain destruction in evolving, radiative SNRs. To facilitate comparison with the previous study by Jones et al. (1996), we adopt the same dust properties as in that paper. We find that the efficiencies of grain destruction are most divergent from those for a steady shock when the thermal history of a shocked gas parcel in the SNR differs significantly from that behind a steady shock. This occurs in shocks with velocities 200 km s(exp -1) for which the remnant is just beginning to go radiative. Assuming SNRs evolve in a warm phase dominated ISM, we find dust destruction timescales are increased by a factor of approximately 2 compared to those of Jones et al. (1996), who assumed a hot gas dominated ISM. Recent estimates of supernova rates and ISM mass lead to another factor of approximately 3 increase in the destruction timescales, resulting in a silicate grain destruction timescale of approximately 2-3 Gyr. These increases, while not able resolve the problem of the discrepant timescales for silicate grain destruction and creation, are an important step towards understanding the origin, and evolution of dust in the ISM.

A Note on Dalton's Law: Myths, Facts, and Implementation

ERIC Educational Resources Information Center

Missen, Ronald W.; Smith, William R.

2005-01-01

Dalton's law for gas mixtures provides one method for predicting the pressure-volume-temperature (PVT) behavior of a gas mixture from the PVT behavior of the individual pure gases that comprise it. An attempt is made to separate fact from myth, to enlarge on a treatment of possible cases for application, and to provide contemporary means on…

Expansion of a Rarefied Gas Cloud in a Vacuum: Asymptotic Treatment

NASA Astrophysics Data System (ADS)

Zhuk, V. I.

2018-02-01

The unsteady expansion of a rarefied gas of finite mass in an unlimited space is studied. The long-time asymptotic behavior of the solution is examined at Knudsen numbers tending to zero. An asymptotic analysis shows that, in the limit of small Knudsen numbers, the behavior of the macroscopic parameters of the expanding gas cloud at long times (i.e., for small density values) has nothing to do with the free-molecular or continuum flow regimes. This conclusion is unexpected and not obvious, but follows from a uniformly suitable solution constructed by applying the method of outer and inner asymptotic expansions. In particular, the unusual temperature behavior is of interest as applied to remote sensing of rocket exhaust plumes.

The relation between the gas, dust and total mass in edge-on spiral galaxies

NASA Astrophysics Data System (ADS)

Allaert, Flor

2015-02-01

Each component of a galaxy plays its own unique role in regulating the galaxy's evolution. In order to understand how galaxies form and evolve, it is therefore crucial to study the distribution and properties of each of the various components, and the links between them, both radially and vertically. The latter is only possible in edge-on systems. We present the HEROES project, which aims to investigate the 3D structure of the interstellar gas, dust, stars and dark matter in a sample of 7 massive early-type spiral galaxies based on a multi-wavelength data set including optical, NIR, FIR and radio data.

Anderson localization of a Tonks-Girardeau gas in potentials with controlled disorder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radic, J.; Bacic, V.; Jukic, D.

We theoretically demonstrate features of Anderson localization in a Tonks-Girardeau gas confined in one-dimensional potentials with controlled disorder. That is, we investigate the evolution of the single-particle density and correlations of a Tonks-Girardeau wave packet in such disordered potentials. The wave packet is initially trapped, the trap is suddenly turned off, and after some time the system evolves into a localized steady state due to Anderson localization. The density tails of the steady state decay exponentially, while the coherence in these tails increases. The latter phenomenon corresponds to the same effect found in incoherent optical solitons.

Hydrogen production using hydrogenase-containing oxygenic photosynthetic organisms

DOEpatents

Melis, Anastasios; Zhang, Liping; Benemann, John R.; Forestier, Marc; Ghirardi, Maria; Seibert, Michael

2006-01-24

A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

Hydrogen Production Using Hydrogenase-Containing Oxygenic Photosynthetic Organisms

DOEpatents

Melis, A.; Zhang, L.; Benemann, J. R.; Forestier, M.; Ghirardi, M.; Seibert, M.

2006-01-24

A reversible physiological process provides for the temporal separation of oxygen evolution and hydrogen production in a microorganism, which includes the steps of growing a culture of the microorganism in medium under illuminated conditions to accumulate an endogenous substrate, depleting from the medium a nutrient selected from the group consisting of sulfur, iron, and/or manganese, sealing the culture from atmospheric oxygen, incubating the culture in light whereby a rate of light-induced oxygen production is equal to or less than a rate of respiration, and collecting an evolved gas. The process is particularly useful to accomplish a sustained photobiological hydrogen gas production in cultures of microorganisms, such as Chlamydomonas reinhardtii.

Structure-Function Relationships in the Gas-Sensing Heme-Dependent Transcription Factors RcoM and DNR

ERIC Educational Resources Information Center

Bowman, Hannah E.

2016-01-01

Transition metals play an important role in many biological processes, however, they are also toxic at high concentrations. Therefore, the uptake and efflux of these metals must be tightly regulated by the cell. Bacteria have evolved a variety of pathways and regulatory systems to monitor the presence and concentration of metals in the cellular…

Arterial Gas Embolism Induced Ageusia (Case Report)

DTIC Science & Technology

2011-07-01

Pulmonary barotraumas are also reported in tbe literature; one case report described delayed onset pul- monary barotrauma in a diver which resolved...be rapidly fatal; it includes shock, pulmonary "chokes", and neurolog ic sequelae resembling cere- brovascular accidents due to nitrogen bubbles...pressures and may cause pneumothoraces. Air may evolve into the mediastinum (mediastinal emphysema ) or the skin (subcutaneous emphysema ). Lastly

An evaluation: The potential of discarded tires as a source of fuel

NASA Technical Reports Server (NTRS)

Collins, L. W.; Downs, W. R.; Gibson, E. K.; Moore, G. W.

1974-01-01

The destructive distillation of rubber tire samples was studied by thermogravimetry, differential scanning calorimetry, combustion calorimetry, and mass spectroscopy. The decomposition reaction was found to be exothermic and produced a mass loss of 65 percent. The gas evolution curves that were obtained indicate that a variety of organic materials are evolved simultaneously during the decomposition of the rubber polymer.

Evolution of Autonomous Self-Righting Behaviors for Articulated Nanorovers

NASA Technical Reports Server (NTRS)

Tunstel, Edward

1999-01-01

Miniature rovers with articulated mobility mechanisms are being developed for planetary surface exploration on Mars and small solar system bodies. These vehicles are designed to be capable of autonomous recovery from overturning during surface operations. This paper describes a computational means of developing motion behaviors that achieve the autonomous recovery function. It proposes a control software design approach aimed at reducing the effort involved in developing self-righting behaviors. The approach is based on the integration of evolutionary computing with a dynamics simulation environment for evolving and evaluating motion behaviors. The automated behavior design approach is outlined and its underlying genetic programming infrastructure is described.

Witnessing Atmospheric Motions in Cool Evolved Stars with VLTI/Amber

NASA Astrophysics Data System (ADS)

Ohnaka, Keiichi

2018-04-01

Studies of the mass loss from stars in late evolutionary stages are of utmost importance for improving our understanding of not only stellar evolution but also the chemical enrichment of galaxies. Despite such importance, the mass loss from cool evolved stars is one of the long-standing problems in stellar astrophysics. Milliarcsecond resolution achieved by optical/infrared long-baseline interferometry provides a unique opportunity to spatially resolve this innermost key region. We have recently succeeded not only in imaging the surface of the red supergiant Antares in the 2.3 micron CO lines in unprecedented detail but also in witnessing, for the first time, the complex gas dynamics over the surface and atmosphere of the star. Our 2-D velocity field map of Antares reveals vigorous upwelling and downdrafting motions of large gas clumps in the atmosphere extending out to 1.7 stellar radii. This suggests that the mass loss in red supergiants may be launched in a turbulent, clumpy manner. We will also present preliminary results of the velocity-resolved imaging of an AGB star. Our work opens an entirely new window to observe stars just like in observations of the Sun.

Evaluation of Pad 18 Spent Mercury Gold Trap Stainless Steel Container Failure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skidmore, E.

Failure of the Pad 18 spent mercury gold trap stainless steel waste container is principally attributed to corrosion induced by degradation of plasticized polyvinyl chloride (pPVC) waste packaging material. Dehydrochlorination of pPVC polymer by thermal and/or radiolytic degradation is well-known to evolve HCl gas, which is highly corrosive to stainless steel and other metals in the presence of moisture. Degradation of the pPVC packaging material was likely caused by radiolysis in the presence of tritium gas within the waste container, though other degradation mechanisms (aging, thermo-oxidation, plasticizer migration) over 30 years storage may have contributed. Corrosion was also likely enhancedmore » by the crevice in the container weld design, and may have been enhanced by the presence of tritiated water. Similar non-failed spent mercury gold trap waste containers did not show radiographic evidence of plastic packaging or trapped free liquid within the container. Therefore, those containers are not expected to exhibit similar failures. Halogenated polymers such as pPVC subject to degradation can evolve halide gases such as HCl, which is corrosive in the presence of moisture and can generate pressure in sealed systems.« less

Mars Phoenix Scout Thermal Evolved Gas Analyzer (TEGA) Database: Thermal Database Development and Analysis

NASA Technical Reports Server (NTRS)

Sutter, B.; Archer, D.; Niles, P. B.; Stein, T. C.; Hamara, D.; Boynton, W. V.; Ming, D. W.

2017-01-01

The Mars Phoenix Scout Lander mission in 2008 examined the history of water, searched for organics, and evaluated the potential for past/present microbial habitability in a martian arctic ice-rich soil [1]. The Thermal Evolved Gas Analyzer (TEGA) instrument measured the isotopic composition of atmospheric CO2 and detected volatile bearing mineralogy (perchlorate, carbonate, hydrated mineral phases) in the martian soil [2-7]. The TEGA data are archived at the Planetary Data System (PDS) Geosciences Node but are reported in forms that require further processing to be of use to the non-TEGA expert. The soil and blank TEGA thermal data are reported as duty cycle and must be converted to differential power (mW) to allow for enthalpy calculations of exothermic/endothermic transitions. The exothermic/endothermic temperatures are also used to determine what phases (inorganic/organic) are present in the sample. The objectives of this work are to: 1) Describe how interpretable thermal data can be created from TEGA data sets on the PDS and 2) Provide additional thermal data interpretation of two Phoenix soils (Baby Bear, Wicked Witch) and include interpretations from three unreported soils (Rosy Red 1, 2, and Burning Coals).

The Chemical Compositions of the SRD Variable Stars. III. KK Aquilae, AG Aurigae, Z Aurigae, W Leo Minoris, and WW Tauri

NASA Astrophysics Data System (ADS)

Giridhar, Sunetra; Lambert, David L.; Gonzalez, Guillermo

2000-12-01

Chemical compositions are derived from high-resolution spectra for five field SRd variables. These supergiants not previously analyzed are shown to be metal poor: KK Aql with [Fe/H]=-1.2, AG Aur with [Fe/H]=-1.8, Z Aur with [Fe/H]=-1.4, W LMi with [Fe/H]=-1.1, and WW Tau with [Fe/H]=-1.1. Their compositions are, except for two anomalies, identical to within the measurement errors to the compositions of subdwarfs, subgiants, and less evolved giants of the same [Fe/H]. One anomaly is an s-process enrichment for KK Aql, the first such enrichment reported for an SRd variable. The second and more remarkable anomaly is a strong lithium enrichment for W LMi, also a first for field SRd variables. The Li I λ6707 profile is not simply that of a photospheric line but includes strong absorption from redshifted gas, suggesting, perhaps, that lithium enrichment results from accretion of Li-rich gas. This potential clue to lithium enrichment is discussed in light of various proposals for lithium synthesis in evolved stars.

[Origin of the oxygen detected by the Viking stations in an analysis of Mars soil].

PubMed

Imshenetskiĭ, A A; Murzakov, B G; Dorofeeva, I K

1978-01-01

Reactions between the mineral limonite and hydrogen peroxide were studied and gases produced thereupon were analysed by gas chromatography. Oxygen did not evolve if limonite was added to hydrogen peroxide frozen at a temperature of dry ice. However, at room temperature, a vigorous chemical reaction occurred and a large amount of oxygen evolved. Apparently, the ground of Mars contains not only hydrated iron oxides but also frozen hydrogen peroxide whose thawing in the incubation chamber of Viking resulted in its catalytic degradation under the action of iron ions. The evidence thus obtained and its comparison with the data of American scientists account for considerable evolution of oxygen detected by Viking upon analysis of the Mars ground.

Using Story to Help Student Understanding of Gas Behavior

ERIC Educational Resources Information Center

Wiebe, Rick; Stinner, Arthur

2010-01-01

Students tend to have a poor understanding of the concept of gas pressure. Usually, gas pressure is taught in terms of the various formulaic gas laws. The development of the concept of gas pressure according to the early Greeks did not include the concept of a vacuum. It was not for another 2000 years that Torricelli proposed that a vacuum can…

Degassing of Cl, F, Li and Be during extrusion and crystallization of the rhyolite dome at Volcán Chaitén, Chile during 2008 and 2009

USGS Publications Warehouse

Lowenstern, Jacob B.; Bleick, Heather; Vazquez, Jorge A.; Castro, Jonathan M.; Larson, Peter B.

2012-01-01

We investigated the distribution of Cl, F, Li, and Be in pumices, obsidians, and crystallized dome rocks at Chaitén volcano in 2008–2009 in order to explore the behavior of these elements during explosive and effusive volcanic activity. Electron and ion microprobe analyses of matrix and inclusion glasses from pumice, obsidian, and microlite-rich dome rock indicate that Cl and other elements were lost primarily during crystallization of the rhyolitic dome after it had approached the surface. Glass in pumice and microlite-free obsidian has 888 ± 121 ppm Cl, whereas residual glass in evolved microlite-rich dome rock generally retains less Cl (as low as 0.7 Mt Cl, with a potential maximum of 1.8 Mt for the entire 0.8-km3 dome. Elemental variations reflect an integrated bulk distribution ratio for Cl > 1.7 (1.7 times more Cl was degassed or incorporated into crystals than remained in the melt). Because Cl is lost dominantly as the very last H2O is degassed, and Cl is minimally (if at all) partitioned into microlites, the integrated vapor/melt distribution ratio for Cl exceeds 200 (200 times more Cl in the evolved vapor than in the melt). Cl is likely lost as HCl, which is readily partitioned into magmatic vapor at low pressure. Cl loss is accelerated by the change in the composition of the residual melt due to microlite growth. Cl loss also may be affected by open-system gas fluxing. Integrated vapor-melt distribution ratios for Li, F, and Be all exceed 1,000. On degassing, an unknown fraction of these volatiles could be immediately dissolved in rainwater.

Multiparameter Analysis of Gas Transport Phenomena in Shale Gas Reservoirs: Apparent Permeability Characterization.

PubMed

Shen, Yinghao; Pang, Yu; Shen, Ziqi; Tian, Yuanyuan; Ge, Hongkui

2018-02-08

The large amount of nanoscale pores in shale results in the inability to apply Darcy's law. Moreover, the gas adsorption of shale increases the complexity of pore size characterization and thus decreases the accuracy of flow regime estimation. In this study, an apparent permeability model, which describes the adsorptive gas flow behavior in shale by considering the effects of gas adsorption, stress dependence, and non-Darcy flow, is proposed. The pore size distribution, methane adsorption capacity, pore compressibility, and matrix permeability of the Barnett and Eagle Ford shales are measured in the laboratory to determine the critical parameters of gas transport phenomena. The slip coefficients, tortuosity, and surface diffusivity are predicted via the regression analysis of the permeability data. The results indicate that the apparent permeability model, which considers second-order gas slippage, Knudsen diffusion, and surface diffusion, could describe the gas flow behavior in the transition flow regime for nanoporous shale. Second-order gas slippage and surface diffusion play key roles in the gas flow in nanopores for Knudsen numbers ranging from 0.18 to 0.5. Therefore, the gas adsorption and non-Darcy flow effects, which involve gas slippage, Knudsen diffusion, and surface diffusion, are indispensable parameters of the permeability model for shale.

Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

NASA Technical Reports Server (NTRS)

Hall, R. M.

1980-01-01

The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

Design Protocols and Analytical Strategies that Incorporate Structural Reliability Models

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1997-01-01

Ceramic matrix composites (CMC) and intermetallic materials (e.g., single crystal nickel aluminide) are high performance materials that exhibit attractive mechanical, thermal and chemical properties. These materials are critically important in advancing certain performance aspects of gas turbine engines. From an aerospace engineer's perspective the new generation of ceramic composites and intermetallics offers a significant potential for raising the thrust/weight ratio and reducing NO(x) emissions of gas turbine engines. These aspects have increased interest in utilizing these materials in the hot sections of turbine engines. However, as these materials evolve and their performance characteristics improve a persistent need exists for state-of-the-art analytical methods that predict the response of components fabricated from CMC and intermetallic material systems. This need provided the motivation for the technology developed under this research effort. Continuous ceramic fiber composites exhibit an increase in work of fracture, which allows for "graceful" rather than catastrophic failure. When loaded in the fiber direction, these composites retain substantial strength capacity beyond the initiation of transverse matrix cracking despite the fact that neither of its constituents would exhibit such behavior if tested alone. As additional load is applied beyond first matrix cracking, the matrix tends to break in a series of cracks bridged by the ceramic fibers. Any additional load is born increasingly by the fibers until the ultimate strength of the composite is reached. Thus modeling efforts supported under this research effort have focused on predicting this sort of behavior. For single crystal intermetallics the issues that motivated the technology development involved questions relating to material behavior and component design. Thus the research effort supported by this grant had to determine the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; map a simplistic failure strength envelope of the material; develop a statistically based reliability computer algorithm, verify the reliability model and computer algorithm, and model stator vanes for rig tests. Thus establishing design protocols that enable the engineer to analyze and predict the mechanical behavior of ceramic composites and intermetallics would mitigate the prototype (trial and error) approach currently used by the engineering community. The primary objective of the research effort supported by this short term grant is the continued creation of enabling technologies for the macroanalysis of components fabricated from ceramic composites and intermetallic material systems. The creation of enabling technologies aids in shortening the product development cycle of components fabricated from the new high technology materials.

Design Protocols and Analytical Strategies that Incorporate Structural Reliability Models

NASA Technical Reports Server (NTRS)

Duffy, Stephen F.

1997-01-01

Ceramic matrix composites (CMC) and intermetallic materials (e.g., single crystal nickel aluminide) are high performance materials that exhibit attractive mechanical, thermal, and chemical properties. These materials are critically important in advancing certain performance aspects of gas turbine engines. From an aerospace engineers perspective the new generation of ceramic composites and intermetallics offers a significant potential for raising the thrust/weight ratio and reducing NO(sub x) emissions of gas turbine engines. These aspects have increased interest in utilizing these materials in the hot sections of turbine engines. However, as these materials evolve and their performance characteristics improve a persistent need exists for state-of-the-art analytical methods that predict the response of components fabricated from CMC and intermetallic material systems. This need provided the motivation for the technology developed under this research effort. Continuous ceramic fiber composites exhibit an increase in work of fracture, which allows for 'graceful' rather than catastrophic failure. When loaded in the fiber direction these composites retain substantial strength capacity beyond the initiation of transverse matrix cracking despite the fact that neither of its constituents would exhibit such behavior if tested alone. As additional load is applied beyond first matrix cracking, the matrix tends to break in a series of cracks bridged by the ceramic fibers. Any additional load is born increasingly by the fibers until the ultimate strength of the composite is reached. Thus modeling efforts supported under this research effort have focused on predicting this sort of behavior. For single crystal intermetallics the issues that motivated the technology development involved questions relating to material behavior and component design. Thus the research effort supported by this grant had to determine the statistical nature and source of fracture in a high strength, NiAl single crystal turbine blade material; map a simplistic future strength envelope of the material; develop a statistically based reliability computer algorithm; verify the reliability model and computer algorithm-, and model stator vanes for rig tests. Thus establishing design protocols that enable the engineer to analyze and predict the mechanical behavior of ceramic composites and intermetallics would mitigate the prototype (trial and error) approach currently used by the engineering community. The primary objective of the research effort supported by this short term grant is the continued creation of enabling technologies for the macro-analysis of components fabricated from ceramic composites and intermetallic material systems. The creation of enabling technologies aids in shortening the product development cycle of components fabricated from the new high technology materials.

A comparison of hardware description languages. [describing digital systems structure and behavior to a computer

NASA Technical Reports Server (NTRS)

Shiva, S. G.

1978-01-01

Several high level languages which evolved over the past few years for describing and simulating the structure and behavior of digital systems, on digital computers are assessed. The characteristics of the four prominent languages (CDL, DDL, AHPL, ISP) are summarized. A criterion for selecting a suitable hardware description language for use in an automatic integrated circuit design environment is provided.

Impact of a University-Based Program on Obese College Students' Physical Activity Behaviors, Attitudes, and Self-Efficacy

ERIC Educational Resources Information Center

Ickes, Melinda J.; McMullen, Jennifer; Pflug, Courtney; Westgate, Philip M.

2016-01-01

Background: More than one third of college students are either overweight or obese, making college campuses an ideal setting to target at risk behaviors while tailoring programs to the evolving lifestyle of college students. Purpose: The purpose of this study was to determine the impact of a 15-week, campus-based lifestyle modification program on…

ECHO: A Computer Based Test for the Measurement of Individualistic, Cooperative, Defensive, and Aggressive Models of Behavior. Occasional Paper No. 30.

ERIC Educational Resources Information Center

Krus, David J.; And Others

This paper describes a test which attempts to measure a group of personality traits by analyzing the actual behavior of the participant in a computer-simulated game. ECHO evolved from an extension and computerization of Horstein and Deutsch's allocation game. The computerized version of ECHO requires subjects to make decisions about the allocation…

Numerical study of effect of the gas-coolant free surface on the droplet fragmentation behavior of coolants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.X.; Anh, B.V.; Dinh, T.N.

1999-07-01

This paper presents results of a numerical investigation on the behavior of melt drops falling in a gas (vapor) space and then penetrating into a liquid volume through the gas-liquid interface. The phenomenon studied here is, usually, observed when a liquid drop falls through air into a water pool and is, specially, of interest when a hypothetical severe reactor core meltdown accident is considered. The objective of this work is to study the effect of the gas-liquid interface on the dynamic evolution of the interaction area between the fragmenting melt drop and water. In the present study, the Navier-Stokes equationsmore » are solved for three phases (gas, liquid and melt-drop) using a higher-order, explicit, numerical method, called Cubic-Interpolated Pseudo-Particle (CIP) method, which is employed in combination with an advanced front-capturing scheme, named the Level Set Algorithm (LSA). By using this method, reasonable physical pictures of droplet deformation and fragmentation during movement in a stationary uniform water pool, and in a gas-liquid two-layer volume, is simulated. Effect of the gas-liquid interface on the drop deformation and fragmentation is analyzed by comparing the simulation results obtained for the two cases. Effects of the drop geometry, and of the flow conditions, on the behavior of the melt drop are also analyzed.« less

Semiempirical limits on the thermal conductivity of intracluster gas

NASA Technical Reports Server (NTRS)

David, Laurence P.; Hughes, John P.; Tucker, Wallace H.

1992-01-01

A semiempirical method for establishing lower limits on the thermal conductivity of hot gas in clusters of galaxies is described. The method is based on the observation that the X-ray imaging data (e.g., Einstein IPC) for clusters are well described by the hydrostatic-isothermal beta model, even for cooling flow clusters beyond about one core radius. In addition, there are strong indications that noncooling flow clusters (like the Coma Cluster) have a large central region (up to several core radii) of nearly constant gas temperature. This suggests that thermal conduction is an effective means of transporting and redistributing the thermal energy of the gas. This in turn has implications for the extent to which magnetic fields in the cluster are effective in reducing the thermal conductivity of the gas. Time-dependent hydrodynamic simulations for the gas in the Coma Cluster under two separate evolutionary scenarios are presented. One scenario assumes that the cluster potential is static and that the gas has an initial adiabatic distribution. The second scenario uses an evolving cluster potential. These models along with analytic results show that the thermal conductivity of the gas in the Coma Cluster cannot be less than 0.1 of full Spitzer conductivity. These models also show that high gas conductivity assists rather than hinders the development of radiative cooling in the central regions of clusters.

Prospecting for marine gas hydrate resources

USGS Publications Warehouse

Boswell, Ray; Shipp, Craig; Reichel, Thomas; Shelander, Dianna; Saeki, Tetsuo; Frye, Matthew; Shedd, William; Collett, Timothy S.; McConnell, Daniel R.

2016-01-01

As gas hydrate energy assessment matures worldwide, emphasis has evolved away from confirmation of the mere presence of gas hydrate to the more complex issue of prospecting for those specific accumulations that are viable resource targets. Gas hydrate exploration now integrates the unique pressure and temperature preconditions for gas hydrate occurrence with those concepts and practices that are the basis for conventional oil and gas exploration. We have aimed to assimilate the lessons learned to date in global gas hydrate exploration to outline a generalized prospecting approach as follows: (1) use existing well and geophysical data to delineate the gas hydrate stability zone (GHSZ), (2) identify and evaluate potential direct indications of hydrate occurrence through evaluation of interval of elevated acoustic velocity and/or seismic events of prospective amplitude and polarity, (3) mitigate geologic risk via regional seismic and stratigraphic facies analysis as well as seismic mapping of amplitude distribution along prospective horizons, and (4) mitigate further prospect risk through assessment of the evidence of gas presence and migration into the GHSZ. Although a wide range of occurrence types might ultimately become viable energy supply options, this approach, which has been tested in only a small number of locations worldwide, has directed prospect evaluation toward those sand-hosted, high-saturation occurrences that were presently considered to have the greatest future commercial potential.

Atomic gas in debris discs

NASA Astrophysics Data System (ADS)

Hales, Antonio S.; Barlow, M. J.; Crawford, I. A.; Casassus, S.

2017-04-01

We have conducted a search for optical circumstellar absorption lines in the spectra of 16 debris disc host stars. None of the stars in our sample showed signs of emission line activity in either Hα, Ca II or Na I, confirming their more evolved nature. Four stars were found to exhibit narrow absorption features near the cores of the photospheric Ca II and Na I D lines (when Na I D data were available). We analyse the characteristics of these spectral features to determine whether they are of circumstellar or interstellar origins. The strongest evidence for circumstellar gas is seen in the spectrum of HD 110058, which is known to host a debris disc observed close to edge-on. This is consistent with a recent ALMA detection of molecular gas in this debris disc, which shows many similarities to the β Pictoris system.

HI Absorption in Merger Remnants

NASA Technical Reports Server (NTRS)

Teng, Stacy H.; Veileux, Sylvain; Baker, Andrew J.

2012-01-01

It has been proposed that ultraluminous infrared galaxies (ULIRGs) pass through a luminous starburst phase, followed by a dust-enshrouded AGN phase, and finally evolve into optically bright "naked" quasars once they shed their gas/dust reservoirs through powerful wind events. We present the results of our recent 21- cm HI survey of 21 merger remnants with the Green Bank Telescope. These remnants were selected from the QUEST (Quasar/ULIRG Evolution Study) sample of ULIRGs and PG quasars; our targets are all bolometrically dominated by AGN and sample all phases of the proposed ULIRG -> IR-excess quasar -> optical quasar sequence. We explore whether there is an evolutionary connection between ULIRGs and quasars by looking for the occurrence of HI absorption tracing neutral gas outflows; our results will allow us to identify where along the sequence the majority of a merger's gas reservoir is expelled.

Analytical methods for toxic gases from thermal degradation of polymers

NASA Technical Reports Server (NTRS)

Hsu, M.-T. S.

1977-01-01

Toxic gases evolved from the thermal oxidative degradation of synthetic or natural polymers in small laboratory chambers or in large scale fire tests are measured by several different analytical methods. Gas detector tubes are used for fast on-site detection of suspect toxic gases. The infrared spectroscopic method is an excellent qualitative and quantitative analysis for some toxic gases. Permanent gases such as carbon monoxide, carbon dioxide, methane and ethylene, can be quantitatively determined by gas chromatography. Highly toxic and corrosive gases such as nitrogen oxides, hydrogen cyanide, hydrogen fluoride, hydrogen chloride and sulfur dioxide should be passed into a scrubbing solution for subsequent analysis by either specific ion electrodes or spectrophotometric methods. Low-concentration toxic organic vapors can be concentrated in a cold trap and then analyzed by gas chromatography and mass spectrometry. The limitations of different methods are discussed.

Simulations of Neon Pellets for Plasma Disruption Mitigation in Tokamaks

NASA Astrophysics Data System (ADS)

Bosviel, Nicolas; Samulyak, Roman; Parks, Paul

2017-10-01

Numerical studies of the ablation of neon pellets in tokamaks in the plasma disruption mitigation parameter space have been performed using a time-dependent pellet ablation model based on the front tracking code FronTier-MHD. The main features of the model include the explicit tracking of the solid pellet/ablated gas interface, a self-consistent evolving potential distribution in the ablation cloud, JxB forces, atomic processes, and an improved electrical conductivity model. The equation of state model accounts for atomic processes in the ablation cloud as well as deviations from the ideal gas law in the dense, cold layers of neon gas near the pellet surface. Simulations predict processes in the ablation cloud and pellet ablation rates and address the sensitivity of pellet ablation processes to details of physics models, in particular the equation of state.

Health-related behaviors and technology usage among college students.

PubMed

Melton, Bridget F; Bigham, Lauren E; Bland, Helen W; Bird, Matthew; Fairman, Ciaran

2014-07-01

To examine associations between technology usage and specific health factors among college students. The research employed was a quantitative, descriptive, cross-sectional design; undergraduate students enrolled in spring 2012 general health education courses were recruited to participate. To explore college students' specific technology usage and health-related behaviors, a 28-item questionnaire was utilized. Statistical significant differences of technology usage were found between 3 of the 4 health-related behaviors under study (BMI, sleep, and nutrition) (p < .05). As technology usage continues to evolve within the college student population, health professionals need to understand its implications on health behaviors.

Tracing the Baryon Cycle within Nearby Galaxies with a next-generation VLA

NASA Astrophysics Data System (ADS)

Kepley, Amanda A.; Leroy, Adam; Murphy, Eric J.; ngVLA Baryon Cycle Science Working Group

2017-01-01

The evolution of galaxies over cosmic time is shaped by the cycling of baryons through these systems, namely the inflow of atomic gas, the formation of molecular structures, the birth of stars, and the expulsion of gas due to associated feedback processes. The best way to study this cycle in detail are observations of nearby galaxies. These systems provide a complete picture of baryon cycling over a wide range of astrophysical conditions. In the next decade, higher resolution/sensitivity observations of such galaxies will fundamentally improve our knowledge of galaxy formation and evolution, allowing us to better interpret higher redshift observations of sources that were rapidly evolving at epochs soon after the Big Bang. In particular, the centimeter-to-millimeter part of the spectrum provides critical diagnostics for each of the key baryon cycling processes and access to almost all phases of gas in galaxies: cool and cold gas (via emission and absorption lines), ionized gas (via free-free continuum and recombination lines), cosmic rays and hot gas (via synchrotron emission and the Sunyaev-Zeldovich effect). This poster highlights a number of key science problems in this area whose solutions require a next-generation radio-mm interferometer such as the next-generation VLA.

Modeling lahar behavior and hazards

USGS Publications Warehouse

Manville, Vernon; Major, Jon J.; Fagents, Sarah A.

2013-01-01

Lahars are highly mobile mixtures of water and sediment of volcanic origin that are capable of traveling tens to > 100 km at speeds exceeding tens of km hr-1. Such flows are among the most serious ground-based hazards at many volcanoes because of their sudden onset, rapid advance rates, long runout distances, high energy, ability to transport large volumes of material, and tendency to flow along existing river channels where populations and infrastructure are commonly concentrated. They can grow in volume and peak discharge through erosion and incorporation of external sediment and/or water, inundate broad areas, and leave deposits many meters thick. Furthermore, lahars can recur for many years to decades after an initial volcanic eruption, as fresh pyroclastic material is eroded and redeposited during rainfall events, resulting in a spatially and temporally evolving hazard. Improving understanding of the behavior of these complex, gravitationally driven, multi-phase flows is key to mitigating the threat to communities at lahar-prone volcanoes. However, their complexity and evolving nature pose significant challenges to developing the models of flow behavior required for delineating their hazards and hazard zones.

The ecological rationality of state-dependent valuation.

PubMed

McNamara, J M; Trimmer, P C; Houston, A I

2012-01-01

Laboratory studies on a range of animals have identified a bias that seems to violate basic principles of rational behavior: a preference is shown for feeding options that previously provided food when reserves were low, even though another option had been found to give the same reward with less delay. The bias presents a challenge to normative models of decision making (which only take account of expected rewards and the state of the animal at the decision time). To understand the behavior, we take a broad ecological perspective and consider how valuation mechanisms evolve when the best action depends upon the environment being faced. We show that in a changing and uncertain environment, state-dependent valuation can be favored by natural selection: Individuals should allow their hunger to affect learning for future decisions. The valuation mechanism that typically evolves produces the kind of behavior seen in standard laboratory tests. By providing an insight into why learning should be affected by the state of an individual, we provide a basis for understanding psychological principles in terms of an animal's ecology.

Efficiency degradation behaviors of current/thermal co-stressed GaN-based blue light emitting diodes with vertical-structure

NASA Astrophysics Data System (ADS)

Liu, Lilin; Ling, Minjie; Yang, Jianfu; Xiong, Wang; Jia, Weiqing; Wang, Gang

2012-05-01

With this work, we demonstrate a three-stage degradation behavior of GaN based LED chips under current/thermal co-stressing. The three stages in sequence are the initial improvement stage, the platform stage, and the rapid degradation stage, indicating that current/thermal co-stressing activates positive effects and negative ones simultaneously, and the dominant degradation mechanisms evolve with aging time. Degradation mechanisms are discussed. Electric current stress has dual characters: damaging the active layers by generating defects and at the same time improving the p-type conductivity by activating the Mg-dopant. High temperature stresses will promote the effects from electric current stresses. The activation of the Mg-dopant will saturate, whereas the generation of defects is carried on in a progressive way. Other mechanisms, such as deterioration of ohmic contacts, also operate. These mechanisms compete/cooperate with each other and evolve with aging time, resulting in the observed three-stage degradation behavior. There exist risks to predict the lifetime of LEDs by a model with a constant accelerated factor.

Correlation of cycles in Lava Lake motion and degassing at Erebus Volcano, Antarctica

NASA Astrophysics Data System (ADS)

Peters, Nial; Oppenheimer, Clive; Killingsworth, Drea Rae; Frechette, Jed; Kyle, Philip

2014-08-01

Several studies at Erebus volcano have recorded pulsatory behavior in many of the observable properties of its active lava lake. A strong correlation between the variations in surface speed of the lake and the composition of gas emitted has previously been noted. While previous studies have shown that the SO2 flux and the surface elevation exhibit pulsatory behavior with a similar period to that of the surface speed and gas composition, suggesting they are linked, a lack of overlap between the different measurements has prevented direct comparisons from being made. Using high time-resolution measurements of surface elevation, surface speed, gas composition, and SO2 flux, we demonstrate for the first time an unambiguous link between the cyclic behavior in each of these properties. We also show that the variation in gas composition may be explained by a subtle change in oxygen fugacity. The cycles are found to be in-phase with each other, with a small but consistent lag of 1-3 min between the peaks in surface elevation and surface speed. Explosive events are found to have no observable effect on the pulsatory behavior beyond the ˜5 min period required for lake refill. The close correspondences between the varying lake surface motion, gas flux and composition, and modeled oxygen fugacity suggest strong links between magma degassing, redox change, and the fluid dynamics of the shallow magmatic system.

Effect of the PTFE content in the gas diffusion layer on water transport in polymer electrolyte fuel cells (PEFCs)

NASA Astrophysics Data System (ADS)

Mortazavi, Mehdi; Tajiri, Kazuya

2014-01-01

The dynamic behavior of a liquid water droplet emerging and detaching from the surface of the gas diffusion layer (GDL) is investigated. The droplet growth and detachment are studied for different polytetrafluoroethylene (PTFE) contents within the GDL and for different superficial gas velocities flowing in the gas channel. To simulate the droplet behavior in the cathode and anode of an operating polymer electrolyte fuel cell, separate experiments are conducted with air and hydrogen being supplied in the gas channel, respectively. Both the superficial gas velocity and the PTFE content within the GDL are found to impact the droplet detachment diameter. Increasing the superficial gas velocity increases the drag force applied on the droplet sitting on the GDL surface. It is observed that the droplet detaches at a smaller diameter for higher superficial gas velocities. The droplets also detach at smaller diameters from GDLs with a higher amount of PTFE. Such observation is justified according to two different points of view: (1) heterogeneous through-plane PTFE distribution through the GDL and (2) reduced GDL surface roughness caused by PTFE loading.

A physical-based gas-surface interaction model for rarefied gas flow simulation

NASA Astrophysics Data System (ADS)

Liang, Tengfei; Li, Qi; Ye, Wenjing

2018-01-01

Empirical gas-surface interaction models, such as the Maxwell model and the Cercignani-Lampis model, are widely used as the boundary condition in rarefied gas flow simulations. The accuracy of these models in the prediction of macroscopic behavior of rarefied gas flows is less satisfactory in some cases especially the highly non-equilibrium ones. Molecular dynamics simulation can accurately resolve the gas-surface interaction process at atomic scale, and hence can predict accurate macroscopic behavior. They are however too computationally expensive to be applied in real problems. In this work, a statistical physical-based gas-surface interaction model, which complies with the basic relations of boundary condition, is developed based on the framework of the washboard model. In virtue of its physical basis, this new model is capable of capturing some important relations/trends for which the classic empirical models fail to model correctly. As such, the new model is much more accurate than the classic models, and in the meantime is more efficient than MD simulations. Therefore, it can serve as a more accurate and efficient boundary condition for rarefied gas flow simulations.

Titan's Gas Behavior During the South Pole Fall

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, Conor A.; Achterberg, Richard K.; Jennings, Donald E.; Gorius, Nicolas; Irwin, Patrick G. J.

2015-11-01

Titan’s southern middle atmosphere has been showing several changes since the start of fall season in 2009. In 2012 a large cloud appeared [1], [2], [3], temperatures became very low and condensation and gas concentration at the South Pole increased [3], [4].In this work we will show the results of gas abundances retrievals in the South Pole and their latitudinal variation changes as the cold season evolved with time.We analyzed several Cassini Composite InfraRed Spectrometer (CIRS [5]) mid-infrared observations of the South Pole acquired during 2013-2014. The data coordinates were converted in order to be centered on the atmospheric pole and refer to the 1 mbar level and not to the surface. We first determine stratospheric temperatures from the same data and latitudes from the n4 band of methane centered around 1300 cm-1. We retrieve the temperature profiles applying a radiative transfer forward model combined with a non-linear optimal estimation inversion method [6]. We then retrieve the main gases abundances and track their variation with latitude using the same method.Latitudinal changes of the main Titan’s gases - HC3N, C4H2, C6H6, C2H2, C2H4, C3H8 and HCN - show different trends in the Southern polar regions over 2014, when winter was getting closer. We observe a ring-shape in some of the gas abundance distributions, with a local maximum peak around -75 deg of latitude. We also observe an increase of abundance of most of the gases toward the south pole, as seen previously in the North during the winter. The observed increase of benzene over the South Pole is definitely evident and strong. References: [1] West, R. A. et al. (2013) BAAS, 45, 305.03. [2] Jennings, D. E. et al. (2012) ApJ, 754, L3. [3] de Kok, R. et al. (2014), Nature, 514, 7520, 65-67. [4] Vinatier S. et al. (2015) Icarus, Volume 250, p. 95-115. [5] Flasar et al. (2004) Space Sci. Rev., 115, 169-297. [6] Irwin, P.G.J. et al. (2008) J. Quant. Spectrosc. Radiat. Trans., 109, 1136-1150.

Multi-Function Gas Fired Heat Pump

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abu-Heiba, Ahmad; Vineyard, Edward Allan

2015-11-01

The aim of this project was to design a residential fuel fired heat pump and further improve efficiency in collaboration with an industry partner – Southwest Gas, the developer of the Nextaire commercial rooftop fuel-fired heat pump. Work started in late 2010. After extensive search for suitable engines, one manufactured by Marathon was selected. Several prototypes were designed and built over the following four years. Design changes were focused on lowering the cost of components and the cost of manufacturing. The design evolved to a final one that yielded the lowest cost. The final design also incorporates noise and vibrationmore » reduction measures that were verified to be effective through a customer survey. ETL certification is currently (as of November 2015) underway. Southwest Gas is currently in talks with GTI to reach an agreement through which GTI will assess the commercial viability and potential of the heat pump. Southwest Gas is searching for investors to manufacture the heat pump and introduce it to the market.« less

Elastic-wave velocity in marine sediments with gas hydrates: Effective medium modeling

USGS Publications Warehouse

Helgerud, M.B.; Dvorkin, J.; Nur, A.; Sakai, A.; Collett, T.

1999-01-01

We offer a first-principle-based effective medium model for elastic-wave velocity in unconsolidated, high porosity, ocean bottom sediments containing gas hydrate. The dry sediment frame elastic constants depend on porosity, elastic moduli of the solid phase, and effective pressure. Elastic moduli of saturated sediment are calculated from those of the dry frame using Gassmann's equation. To model the effect of gas hydrate on sediment elastic moduli we use two separate assumptions: (a) hydrate modifies the pore fluid elastic properties without affecting the frame; (b) hydrate becomes a component of the solid phase, modifying the elasticity of the frame. The goal of the modeling is to predict the amount of hydrate in sediments from sonic or seismic velocity data. We apply the model to sonic and VSP data from ODP Hole 995 and obtain hydrate concentration estimates from assumption (b) consistent with estimates obtained from resistivity, chlorinity and evolved gas data. Copyright 1999 by the American Geophysical Union.

Evolution from Rydberg gas to ultracold plasma in a supersonic atomic beam of Xe

NASA Astrophysics Data System (ADS)

Hung, J.; Sadeghi, H.; Schulz-Weiling, M.; Grant, E. R.

2014-08-01

A Rydberg gas of xenon, entrained in a supersonic atomic beam, evolves slowly to form an ultracold plasma. In the early stages of this evolution, when the free-electron density is low, Rydberg atoms undergo long-range \\ell -mixing collisions, yielding states of high orbital angular momentum. The development of high-\\ell states promotes dipole-dipole interactions that help to drive Penning ionization. The electron density increases until it reaches the threshold for avalanche. Ninety μs after the production of a Rydberg gas with the initial state, {{n}_{0}}{{\\ell }_{0}}=42d, a 432 V cm-1 electrostatic pulse fails to separate charge in the excited volume, an effect which is ascribed to screening by free electrons. Photoexcitation cross sections, observed rates of \\ell -mixing, and a coupled-rate-equation model simulating the onset of the electron-impact avalanche point consistently to an initial Rydberg gas density of 5\\times {{10}^{8}}\\;c{{m}^{-3}}.

A VLT/FORS2 spectroscopic survey of individual stars in a transforming dwarf galaxy

NASA Astrophysics Data System (ADS)

Battaglia, G.; Kacharov, N.; Rejkuba, M.

2017-03-01

Understanding the properties of dwarf galaxies is important not only to put them in their proper cosmological context, but also to understand the formation and evolution of the most common type of galaxies. Dwarf galaxies are divided into two main classes, dwarf irregulars (dIrrs) and dwarf spheroidals (dSphs), which differ from each other mainly because the former are gas-rich objects currently forming stars, while the latter are gas-deficient with no on-going star formation. Transition types (dT) are thought to represent dIs in the process of losing their gas, and can therefore shed light into the possible process of dwarf irregulars (dIrrs) becoming gas-deficient, passively evolving galaxies. Here we present preliminary results from our wide-area VLT/FORS2 MXU spectroscopic survey of the Phoenix dT, from which we obtained line-of-sight velocities and metallicities from the nIR Ca II triplet lines for a large sample of individual Red Giant Branch stars.

NEUTRONIC REACTOR OPERATIONAL METHOD AND CORE SYSTEM

DOEpatents

Winters, C.E.; Graham, C.B.; Culver, J.S.; Wilson, R.H.

1960-07-19

Homogeneous neutronic reactor systems are described wherein an aqueous fuel solution is continuously circulated through a spherical core tank. The pumped fuel solution-is injected tangentially into the hollow spherical interior, thereby maintaining vigorous rotation of the solution within the tank in the form of a vortex; gaseous radiolytic decomposition products concentrate within the axial vortex cavity. The evolved gas is continuously discharged through a gas- outlet port registering with an extremity of the vortex cavity. and the solution stream is discharged through an annular liquid outlet port concentrically encircling the gas outlet by virtue of which the vortex and its cavity are maintained precisely axially aligned with the gas outlet. A primary heat exchanger extracts useful heat from the hot effluent fuel solution before its recirculation into the core tank. Hollow cylinders and other alternative core- tank configurations defining geometric volumes of revolution about a principal axis are also covered. AEC's Homogeneous Reactor Experiment No. 1 is a preferred embodiment.

The evolution of risk perceptions related to bovine spongiform encephalopathy--Canadian consumer and producer behavior.

PubMed

Yang, Jun; Goddard, Ellen

2011-01-01

In this study the dynamics of risk perceptions related to bovine spongiform encephalopathy (BSE) held by Canadian consumers and cow-calf producers were evaluated. Since the first domestic case of BSE in 2003, Canadian consumers and cow-calf producers have needed to make decisions on whether or not their purchasing/production behavior should change. Such changes in their behavior may relate to their levels of risk perceptions about BSE, risk perceptions that may be evolving over time and be affected by BSE media information available. An econometric analysis of the behavior of consumers and cow-calf producers might identify the impacts of evolving BSE risk perceptions. Risk perceptions related to BSE are evaluated through observed market behavior, an approach that differs from traditional stated preference approaches to eliciting risk perceptions at a particular point in time. BSE risk perceptions may be specified following a Social Amplification of Risk Framework (SARF) derived from sociology, psychology, and economics. Based on the SARF, various quality and quantity indices related to BSE media information are used as explanatory variables in risk perception equations. Risk perceptions are approximated using a predictive difference approach as defined by Liu et al. (1998). Results showed that Canadian consumer and cow-calf producer risk perceptions related to BSE have been amplified or attenuated by both quantity and quality of BSE media information. Government policies on risk communications need to address the different roles of BSE information in Canadian consumers' and cow-calf producers' behavior.

Facilitating Students' Interaction with Real Gas Properties Using a Discovery-Based Approach and Molecular Dynamics Simulations

ERIC Educational Resources Information Center

Sweet, Chelsea; Akinfenwa, Oyewumi; Foley, Jonathan J., IV

2018-01-01

We present an interactive discovery-based approach to studying the properties of real gases using simple, yet realistic, molecular dynamics software. Use of this approach opens up a variety of opportunities for students to interact with the behaviors and underlying theories of real gases. Students can visualize gas behavior under a variety of…

Theoretical Insight into Shocked Gases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leiding, Jeffery Allen

2016-09-29

I present the results of statistical mechanical calculations on shocked molecular gases. This work provides insight into the general behavior of shock Hugoniots of gas phase molecular targets with varying initial pressures. The dissociation behavior of the molecules is emphasized. Impedance matching calculations are performed to determine the maximum degree of dissociation accessible for a given flyer velocity as a function of initial gas pressure.

Curious chiral cases of caddisfly larvae: handed behavior, asymmetric forms, evolutionary history.

PubMed

Hinchliffe, Robert; Palmer, A R

2010-10-01

Studies of right-left asymmetries have yielded valuable insights into the mechanisms of both development and evolution. Larvae from several groups of caddisflies (Trichoptera) build portable asymmetrical cases within which they live. In nearly all species that build spiral-walled tubular cases, the direction of wall coiling is random (equal numbers of dextral and sinistral cases within species) whereas in all species that build helicospiral, snail-like cases the direction of coiling is exclusively dextral. Asymmetrical tubes result from handed behavior, and ∼20% of larvae removed from a spiral-walled, tubular case build a replacement case of opposite chirality. So handed behavior (and hence direction of tube-wall spiraling) is likely learned rather than determined genetically. Asymmetrical larval cases appear to have evolved at least seven times in the Trichoptera, five times as spiral-walled tubes and twice as snail-like helicospiral cases. Helicospiral cases may reduce vulnerability to predation by mimicking snail shells, whereas spiral arrangements of vegetation fragments in tube walls may be more robust mechanically than other arrangements, but experimental evidence is lacking. Within one family (Phryganeidae), one or perhaps two species exhibit an excess of sinistral-walled cases, suggesting that genes that bias handed behavior in a particular direction evolved after handed behaviors already existed (genetic assimilation). © The Author 2010. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

The Evolution of Sonic Ecosystems

NASA Astrophysics Data System (ADS)

McCormack, Jon

This chapter describes a novel type of artistic artificial life software environment. Agents that have the ability to make and listen to sound populate a synthetic world. An evolvable, rule-based classifier system drives agent behavior. Agents compete for limited resources in a virtual environment that is influenced by the presence and movement of people observing the system. Electronic sensors create a link between the real and virtual spaces, virtual agents evolve implicitly to try to maintain the interest of the human audience, whose presence provides them with life-sustaining food.

Reaction behavior of SO2 in the sintering process with flue gas recirculation.

PubMed

Yu, Zhi-Yuan; Fan, Xiao-Hui; Gan, Min; Chen, Xu-Ling; Chen, Qiang; Huang, Yun-Song

2016-07-01

The primary goal of this paper is to reveal the reaction behavior of SO2 in the sinter zone, combustion zone, drying-preheating zone, and over-wet zone during flue gas recirculation (FGR) technique. The results showed that SO2 retention in the sinter zone was associated with free-CaO in the form of CaSO3/CaSO4, and the SO2 adsorption reached a maximum under 900ºC. SO2 in the flue gas came almost from the combustion zone. One reaction behavior was the oxidation of sulfur in the sintering mix when the temperature was between 800 and 1000ºC; the other behavior was the decomposition of sulfite/sulfate when the temperature was over 1000ºC. However, the SO2 adsorption in the sintering bed mainly occurred in the drying-preheating zone, adsorbed by CaCO3, Ca(OH)2, and CaO. When the SO2 adsorption reaction in the drying-preheating zone reached equilibrium, the excess SO2 gas continued to migrate to the over-wet zone and was then absorbed by Ca(OH)2 and H2O. The emission rising point of SO2 moved forward in combustion zone, and the concentration of SO2 emissions significantly increased in the case of flue gas recirculation (FGR) technique. Aiming for the reuse of the sensible heat and a reduction in exhaust gas emission, the FGR technique is proposed in the iron ore sintering process. When using the FGR technique, SO2 emission in exhaust gas gets changed. In practice, the application of the FGR technique in a sinter plant should be cooperative with the flue gas desulfurization (FGD) technique. Thus, it is necessary to study the influence of the FGR technique on SO2 emissions because it will directly influence the demand and design of the FGD system.

The evolution of distributed sensing and collective computation in animal populations

PubMed Central

Hein, Andrew M; Rosenthal, Sara Brin; Hagstrom, George I; Berdahl, Andrew; Torney, Colin J; Couzin, Iain D

2015-01-01

Many animal groups exhibit rapid, coordinated collective motion. Yet, the evolutionary forces that cause such collective responses to evolve are poorly understood. Here, we develop analytical methods and evolutionary simulations based on experimental data from schooling fish. We use these methods to investigate how populations evolve within unpredictable, time-varying resource environments. We show that populations evolve toward a distinctive regime in behavioral phenotype space, where small responses of individuals to local environmental cues cause spontaneous changes in the collective state of groups. These changes resemble phase transitions in physical systems. Through these transitions, individuals evolve the emergent capacity to sense and respond to resource gradients (i.e. individuals perceive gradients via social interactions, rather than sensing gradients directly), and to allocate themselves among distinct, distant resource patches. Our results yield new insight into how natural selection, acting on selfish individuals, results in the highly effective collective responses evident in nature. DOI: http://dx.doi.org/10.7554/eLife.10955.001 PMID:26652003

Gas Release as a Deformation Signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauer, Stephen J.

Radiogenic noble gases are contained in crustal rock at inter and intra granular sites. The gas composition depends on lithology, geologic history, fluid phases, and the aging effect by decay of U, Th, and K. The isotopic signature of noble gases found in rocks is vastly different than that of the atmosphere which is contributed by a variety of sources. When rock is subjected to stress conditions exceeding about half its yield strength, micro-cracks begin to form. As rock deformation progresses a fracture network evolves, releasing trapped noble gases and changing the transport properties to gas migration. Thus, changes inmore » gas emanation and noble gas composition from rocks could be used to infer changes in stress-state and deformation. The purpose of this study has been to evaluate the effect of deformation/strain rate upon noble gas release. Four triaxial experiments were attempted for a strain rate range of %7E10-8 /s (180,000s) to %7E 10-4/s (500s); the three fully successful experiments (at the faster strain rates) imply the following: (1) helium is measurably released for all strain rates during deformation, this release is in amounts 1-2 orders of magnitude greater than that present in the air, and (2) helium gas release increases with decreasing strain rate.« less

Extinction Events Can Accelerate Evolution

PubMed Central

Lehman, Joel; Miikkulainen, Risto

2015-01-01

Extinction events impact the trajectory of biological evolution significantly. They are often viewed as upheavals to the evolutionary process. In contrast, this paper supports the hypothesis that although they are unpredictably destructive, extinction events may in the long term accelerate evolution by increasing evolvability. In particular, if extinction events extinguish indiscriminately many ways of life, indirectly they may select for the ability to expand rapidly through vacated niches. Lineages with such an ability are more likely to persist through multiple extinctions. Lending computational support for this hypothesis, this paper shows how increased evolvability will result from simulated extinction events in two computational models of evolved behavior. The conclusion is that although they are destructive in the short term, extinction events may make evolution more prolific in the long term. PMID:26266804

Evolutionary robotics simulations help explain why reciprocity is rare in nature

PubMed Central

André, Jean-Baptiste; Nolfi, Stefano

2016-01-01

The relative rarity of reciprocity in nature, contrary to theoretical predictions that it should be widespread, is currently one of the major puzzles in social evolution theory. Here we use evolutionary robotics to solve this puzzle. We show that models based on game theory are misleading because they neglect the mechanics of behavior. In a series of experiments with simulated robots controlled by artificial neural networks, we find that reciprocity does not evolve, and show that this results from a general constraint that likely also prevents it from evolving in the wild. Reciprocity can evolve if it requires very few mutations, as is usually assumed in evolutionary game theoretic models, but not if, more realistically, it requires the accumulation of many adaptive mutations. PMID:27616139

Regolith Evolved Gas Analyzer

NASA Technical Reports Server (NTRS)

Hoffman, John H.; Hedgecock, Jud; Nienaber, Terry; Cooper, Bonnie; Allen, Carlton; Ming, Doug

2000-01-01

The Regolith Evolved Gas Analyzer (REGA) is a high-temperature furnace and mass spectrometer instrument for determining the mineralogical composition and reactivity of soil samples. REGA provides key mineralogical and reactivity data that is needed to understand the soil chemistry of an asteroid, which then aids in determining in-situ which materials should be selected for return to earth. REGA is capable of conducting a number of direct soil measurements that are unique to this instrument. These experimental measurements include: (1) Mass spectrum analysis of evolved gases from soil samples as they are heated from ambient temperature to 900 C; and (2) Identification of liberated chemicals, e.g., water, oxygen, sulfur, chlorine, and fluorine. REGA would be placed on the surface of a near earth asteroid. It is an autonomous instrument that is controlled from earth but does the analysis of regolith materials automatically. The REGA instrument consists of four primary components: (1) a flight-proven mass spectrometer, (2) a high-temperature furnace, (3) a soil handling system, and (4) a microcontroller. An external arm containing a scoop or drill gathers regolith samples. A sample is placed in the inlet orifice where the finest-grained particles are sifted into a metering volume and subsequently moved into a crucible. A movable arm then places the crucible in the furnace. The furnace is closed, thereby sealing the inner volume to collect the evolved gases for analysis. Owing to the very low g forces on an asteroid compared to Mars or the moon, the sample must be moved from inlet to crucible by mechanical means rather than by gravity. As the soil sample is heated through a programmed pattern, the gases evolved at each temperature are passed through a transfer tube to the mass spectrometer for analysis and identification. Return data from the instrument will lead to new insights and discoveries including: (1) Identification of the molecular masses of all of the gases liberated from heated soil samples; (2) Identification of the asteroid soil mineralogy to aid in the selection process for returned samples; (3) Existence of oxygen in the asteroid soil and the potential for in-situ resource utilization (ISRU); and (4) Existence of water and other volatiles in the asteroid soil. Additional information is contained in the original extended abstract.