Maximum entropy perception-action space: a Bayesian model of eye movement selection

NASA Astrophysics Data System (ADS)

Colas, Francis; Bessière, Pierre; Girard, Benoît

2011-03-01

In this article, we investigate the issue of the selection of eye movements in a free-eye Multiple Object Tracking task. We propose a Bayesian model of retinotopic maps with a complex logarithmic mapping. This model is structured in two parts: a representation of the visual scene, and a decision model based on the representation. We compare different decision models based on different features of the representation and we show that taking into account uncertainty helps predict the eye movements of subjects recorded in a psychophysics experiment. Finally, based on experimental data, we postulate that the complex logarithmic mapping has a functional relevance, as the density of objects in this space in more uniform than expected. This may indicate that the representation space and control strategies are such that the object density is of maximum entropy.

Diameter-density relationships provide tentative spacing guidelines for Eucalyptus saligna in Hawaii

Treesearch

Dean S. DeBell; Craig D. Whitesell

1988-01-01

Trials have been established in Hawaii to develop spacing guidelines for Eucalyptus saligna plantations. Substantial competition-related mortality occurred in densely planted plots of three spacing trials. Data on stand diameter and surviving number of trees on these plots were plotted in logarithmic form to estimate a "self-thinning" or...

The development of a volatile organics concentrator for use in monitoring Space Station water quality

NASA Technical Reports Server (NTRS)

Bodek, Itamar; Ehntholt, Daniel J.; Stolki, Thomas J.; Valentine, James R.; Trabanino, Rudy; Webb, Johanna V.; Sauer, Richard L.

1991-01-01

A breadboard concept of a volatile organics concentrator (VOC) is manufactured and tested for optimized water-quality analysis in a space environment. The VOC system is attached to a gas chromatograph/mass spectrometer to analyze the volatile chemicals relevant to the operation of Space Station Freedom. The preliminary tests include: (1) comparisons with analyses based on direct on-column injections of standards; (2) analyses of iodinated volatile organics; (3) comparisons of nitrogen vs helium as the chromatography carrier gas; and (4) measurements of collection efficiency. The VOC can analyze EPA method-624 analytes at comparable detection using flame-ionization detection and can analyze volatile iodinated compounds. The breadboard has good reproducibility and can use nitrogen as a carrier gas; good results are noted for the collection and concentration levels and for water removal.

Gauge boson exchange in AdS d+1

NASA Astrophysics Data System (ADS)

D'Hoker, Eric; Freedman, Daniel Z.

1999-04-01

We study the amplitude for exchange of massless gauge bosons between pairs of massive scalar fields in anti-de Sitter space. In the AdS/CFT correspondence this amplitude describes the contribution of conserved flavor symmetry currents to 4-point functions of scalar operators in the boundary conformal theory. A concise, covariant, Y2K compatible derivation of the gauge boson propagator in AdS d + 1 is given. Techniques are developed to calculate the two bulk integrals over AdS space leading to explicit expressions or convenient, simple integral representations for the amplitude. The amplitude contains leading power and sub-leading logarithmic singularities in the gauge boson channel and leading logarithms in the crossed channel. The new methods of this paper are expected to have other applications in the study of the Maldacena conjecture.

Resumming double non-global logarithms in the evolution of a jet

NASA Astrophysics Data System (ADS)

Hatta, Y.; Iancu, E.; Mueller, A. H.; Triantafyllopoulos, D. N.

2018-02-01

We consider the Banfi-Marchesini-Smye (BMS) equation which resums `non-global' energy logarithms in the QCD evolution of the energy lost by a pair of jets via soft radiation at large angles. We identify a new physical regime where, besides the energy logarithms, one has to also resum (anti)collinear logarithms. Such a regime occurs when the jets are highly collimated (boosted) and the relative angles between successive soft gluon emissions are strongly increasing. These anti-collinear emissions can violate the correct time-ordering for time-like cascades and result in large radiative corrections enhanced by double collinear logs, making the BMS evolution unstable beyond leading order. We isolate the first such a correction in a recent calculation of the BMS equation to next-to-leading order by Caron-Huot. To overcome this difficulty, we construct a `collinearly-improved' version of the leading-order BMS equation which resums the double collinear logarithms to all orders. Our construction is inspired by a recent treatment of the Balitsky-Kovchegov (BK) equation for the high-energy evolution of a space-like wavefunction, where similar time-ordering issues occur. We show that the conformal mapping relating the leading-order BMS and BK equations correctly predicts the physical time-ordering, but it fails to predict the detailed structure of the collinear improvement.

Sources and production of organic aerosol in Mexico City: insights from the combination of a chemical transport model (PMCAMx-2008) and measurements during MILAGRO

NASA Astrophysics Data System (ADS)

Tsimpidi, A. P.; Karydis, V. A.; Zavala, M.; Lei, W.; Bei, N.; Molina, L.; Pandis, S. N.

2010-11-01

Urban areas are large sources of organic aerosols and their precursors. Nevertheless, the contributions of primary (POA) and secondary organic aerosol (SOA) to the observed particulate matter levels have been difficult to quantify. In this study the three-dimensional chemical transport model PMCAMx-2008 is used to investigate the temporal and geographic variability of organic aerosol in the Mexico City Metropolitan Area (MCMA) during the MILAGRO campaign that took place in the spring of 2006. The organic module of PMCAMx-2008 is based on the volatility basis-set approach: both primary and secondary organic components are assumed to be semi-volatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The MCMA emission inventory is modified and the POA emissions are distributed by volatility based on dilution experiments. The model predictions are compared with observations from four different types of sites, an urban (T0), a suburban (T1), a rural (T2), and an elevated site in Pico Tres Padres (PTP). The performance of the model in reproducing organic mass concentrations in these sites was encouraging. The average predicted PM1 OA concentration in T0, T1, and T2 was 18 μg m-3, 11.7 μg m-3, and 10.5 μg m-3 respectively, while the corresponding measured values were 17.2 μg m-3, 11 μg m-3, and 9 μg m-3. The average predicted fresh primary OA concentrations were 4.4 μg m-3 at T0, 1.2 μg m-3 at T1 and 1.7 μg m-3 at PTP in reasonably good agreement with the corresponding PMF analysis estimates based on the AMS observations of 4.5, 1.3, and 2.9 μg m-3 respectively. The model reproduced reasonably well the average oxygenated OA (OOA) levels in T0 (7.5 μg m-3 predicted versus 7.5 μg m-3 measured), in T1 (6.3 μg m-3 predicted versus 4.6 μg m-3 measured) and in PTP (6.6 μg m-3 predicted versus 5.9 μg m-3 measured). Inside Mexico City, the locally produced OA is predicted to be on average 53% fresh primary (POA), 11% semi-volatile (S-SOA) and intermediate volatile (I-SOA) organic aerosol, and 36% traditional SOA from the oxidation of VOCs (V-SOA). The long range transport from biomass burning activities and other sources in Mexico is predicted to contribute on average almost as much as the local sources during the MILAGRO period.

The micro-environmental impact of volatile organic compound emissions from large-scale assemblies of people in a confined space

USDA-ARS?s Scientific Manuscript database

Large-scale assemblies of people in a con'ned space can exert signi'cant impacts on the local air chemistry due to human emissions of volatile organics. Variations of air-quality in such small scale can be studied by quantifying 'ngerprint volatile organic compounds (VOCs) such as acetone, toluene, ...

Modeling and complexity of stochastic interacting Lévy type financial price dynamics

NASA Astrophysics Data System (ADS)

Wang, Yiduan; Zheng, Shenzhou; Zhang, Wei; Wang, Jun; Wang, Guochao

2018-06-01

In attempt to reproduce and investigate nonlinear dynamics of security markets, a novel nonlinear random interacting price dynamics, which is considered as a Lévy type process, is developed and investigated by the combination of lattice oriented percolation and Potts dynamics, which concerns with the instinctive random fluctuation and the fluctuation caused by the spread of the investors' trading attitudes, respectively. To better understand the fluctuation complexity properties of the proposed model, the complexity analyses of random logarithmic price return and corresponding volatility series are preformed, including power-law distribution, Lempel-Ziv complexity and fractional sample entropy. In order to verify the rationality of the proposed model, the corresponding studies of actual security market datasets are also implemented for comparison. The empirical results reveal that this financial price model can reproduce some important complexity features of actual security markets to some extent. The complexity of returns decreases with the increase of parameters γ1 and β respectively, furthermore, the volatility series exhibit lower complexity than the return series

Logarithmic conformal field theory

NASA Astrophysics Data System (ADS)

Gainutdinov, Azat; Ridout, David; Runkel, Ingo

2013-12-01

Conformal field theory (CFT) has proven to be one of the richest and deepest subjects of modern theoretical and mathematical physics research, especially as regards statistical mechanics and string theory. It has also stimulated an enormous amount of activity in mathematics, shaping and building bridges between seemingly disparate fields through the study of vertex operator algebras, a (partial) axiomatisation of a chiral CFT. One can add to this that the successes of CFT, particularly when applied to statistical lattice models, have also served as an inspiration for mathematicians to develop entirely new fields: the Schramm-Loewner evolution and Smirnov's discrete complex analysis being notable examples. When the energy operator fails to be diagonalisable on the quantum state space, the CFT is said to be logarithmic. Consequently, a logarithmic CFT is one whose quantum space of states is constructed from a collection of representations which includes reducible but indecomposable ones. This qualifier arises because of the consequence that certain correlation functions will possess logarithmic singularities, something that contrasts with the familiar case of power law singularities. While such logarithmic singularities and reducible representations were noted by Rozansky and Saleur in their study of the U (1|1) Wess-Zumino-Witten model in 1992, the link between the non-diagonalisability of the energy operator and logarithmic singularities in correlators is usually ascribed to Gurarie's 1993 article (his paper also contains the first usage of the term 'logarithmic conformal field theory'). The class of CFTs that were under control at this time was quite small. In particular, an enormous amount of work from the statistical mechanics and string theory communities had produced a fairly detailed understanding of the (so-called) rational CFTs. However, physicists from both camps were well aware that applications from many diverse fields required significantly more complicated non-rational theories. Examples include critical percolation, supersymmetric string backgrounds, disordered electronic systems, sandpile models describing avalanche processes, and so on. In each case, the non-rationality and non-unitarity of the CFT suggested that a more general theoretical framework was needed. Driven by the desire to better understand these applications, the mid-1990s saw significant theoretical advances aiming to generalise the constructs of rational CFT to a more general class. In 1994, Nahm introduced an algorithm for computing the fusion product of representations which was significantly generalised two years later by Gaberdiel and Kausch who applied it to explicitly construct (chiral) representations upon which the energy operator acts non-diagonalisably. Their work made it clear that underlying the physically relevant correlation functions are classes of reducible but indecomposable representations that can be investigated mathematically to the benefit of applications. In another direction, Flohr had meanwhile initiated the study of modular properties of the characters of logarithmic CFTs, a topic which had already evoked much mathematical interest in the rational case. Since these seminal theoretical papers appeared, the field has undergone rapid development, both theoretically and with regard to applications. Logarithmic CFTs are now known to describe non-local observables in the scaling limit of critical lattice models, for example percolation and polymers, and are an integral part of our understanding of quantum strings propagating on supermanifolds. They are also believed to arise as duals of three-dimensional chiral gravity models, fill out hidden sectors in non-rational theories with non-compact target spaces, and describe certain transitions in various incarnations of the quantum Hall effect. Other physical applications range from two-dimensional turbulence and non-equilibrium systems to aspects of the AdS/CFT correspondence and describing supersymmetric sigma models beyond the topological sector. We refer the reader to the reviews in this collection for further applications and details. More recently, our understanding of logarithmic CFT has improved dramatically thanks largely to a better understanding of the underlying mathematical structures. This includes those associated to the vertex operator algebras themselves (representations, characters, modular transformations, fusion, braiding) as well as structures associated with applications to two-dimensional statistical models (diagram algebras, eg. Temperley-Lieb quantum groups). Not only are we getting to the point where we understand how these structures differ from standard (rational) theories, but we are starting to tackle applications both in the boundary and bulk settings. It is now clear that the logarithmic case is generic, so it is this case that one should expect to encounter in applications. We therefore feel that it is timely to review what has been accomplished in order to disseminate this improved understanding and motivate further applications. We now give a quick overview of the articles that constitute this special issue. Adamović and Milas provide a detailed summary of their rigorous results pertaining to logarithmic vertex operator (super)algebras constructed from lattices. This survey discusses the C2-cofiniteness of the (p, p') triplet models (this is the generalisation of rationality to the logarithmic setting), describes Zhu's algebra for (some of) these theories and outlines the difficulties involved in explicitly constructing the modules responsible for their logarithmic nature. Cardy gives an account of a popular approach to logarithmic theories that regards them, heuristically at least, as limits of ordinary (but non-rational) CFTs. More precisely, it seems that any given correlator may be computed as a limit of standard (non-logarithmic) correlators, any logarithmic singularities that arise do so because of a degeneration when taking the limit. He then illustrates this phenomenon in several theories describing statistical lattice models including the n → 0 limit of the O(n ) model and the Q → 1 limit of the Q-state Potts model. Creutzig and Ridout review the continuum approach to logarithmic CFT, using the percolation (boundary) CFT to detail the connection between module structure and logarithmic singularities in correlators before describing their proposed solution to the thorny issue of generalising modular data and Verlinde formulae to the logarithmic setting. They illustrate this proposal using the three best-understood examples of logarithmic CFTs: the (1, 2) models, related to symplectic fermions; the fractional level WZW model on , related to the beta gamma ghosts; and the WZW model on GL(1|1). The analysis in each case requires that the spectrum be continuous; C2-cofinite models are only recovered as orbifolds. Flohr and Koehn consider the characters of the irreducible modules in the spectrum of a CFT and discuss why these only span a proper subspace of the space of torus vacuum amplitudes in the logarithmic case. This is illustrated explicitly for the (1, 2) triplet model and conclusions are drawn for the action of the modular group. They then note that the irreducible characters of this model also admit fermionic sum forms which seem to fit well into Nahmrsquo;s well-known conjecture for rational theories. Quasi-particle interpretations are also introduced, leading to the conclusion that logarithmic C2-cofinite theories are not so terribly different to rational theories, at least in some respects. Fuchs, Schweigert and Stigner address the problem of constructing local logarithmic CFTs starting from the chiral theory. They first review the construction of the local theory in the non-logarithmic setting from an angle that will then generalise to logarithmic theories. In particular, they observe that the bulk space can be understood as a certain coend. The authors then show how to carry out the construction of the bulk space in the category of modules over a factorisable ribbon Hopf algebra, which shares many properties with the braided categories arising from logarithmic chiral theories. The authors proceed to construct the analogue of all-genus correlators in their setting and establish invariance under the mapping class group, i.e. locality of the correlators. Gainutdinov, Jacobsen, Read, Saleur and Vasseur review their approach based on the assumption that certain classes of logarithmic CFTs admit lattice regularisations with local degrees of freedom, for example quantum spin chains (with local interactions). They therefore study the finite-dimensional algebras generated by the hamiltonian densities (typically the Temperley-Lieb algebras and their extensions) that describe the dynamics of these lattice models. The authors then argue that the lattice algebras exhibit, in finite size, mathematical properties that are in correspondence with those of their continuum limits, allowing one to predict continuum structures directly from the lattice. Moreover, the lattice models considered admit quantum group symmetries that play a central role in the algebraic analysis (representation structure and fusion). Grumiller, Riedler, Rosseel and Zojer review the role that logarithmic CFTs may play in certain versions of the AdS/CFT correspondence, particularly for what is known as topologically massive gravity (TMG). This has been a very active subject over the last five years and the article takes great care to disentangle the contributions from the many groups that have participated. They begin with some general remarks on logarithmic behaviour, much in the spirit of Cardyrsquo;s review, before detailing the distinction between the chiral (no logs) and logarithmic proposals for critical TMG. The latter is then subjected to various consistency checks before discussing evidence for logarithmic behaviour in more general classes of gravity theories including those with boundaries, supersymmetry and galilean relativity. Gurarie has written an historical overview of his seminal contributions to this field, putting his results (and those of his collaborators) in the context of understanding applications to condensed matter physics. This includes the link between the non-diagonalisability of L0 and logarithmic singularities, a study of the c → 0 catastrophe, and a proposed resolution involving supersymmetric partners for the stress-energy tensor and its logarithmic partner field. Henkel and Rouhani describe a direction in which logarithmic singularities are observed in correlators of non-relativistic field theories. Their review covers the appropriate modifications of conformal invariance that are appropriate to non-equilibrium statistical mechanics, strongly anisotropic critical points and certain variants of TMG. The main variation away from the standard relativistic idea of conformal invariance is that time is explicitly distinguished from space when considering dilations and this leads to a variety of algebraic structures to explore. In this review, the link between non-diagonalisable representations and logarithmic singularities in correlators is generalised to these algebras, before two applications of the theory are discussed. Huang and Lepowsky give a non-technical overview of their work on braided tensor structures on suitable categories of representations of vertex operator algebras. They also place their work in historic context and compare it to related approaches. The authors sketch their construction of the so-called P(z)-tensor product of modules of a vertex operator algebra, and the construction of the associativity isomorphisms for this tensor product. They proceed to give a guide to their works leading to the first authorrsquo;s proof of modularity for a class of vertex operator algebras, and to their works, joint with Zhang, on logarithmic intertwining operators and the resulting tensor product theory. Morin-Duchesne and Saint-Aubin have contributed a research article describing their recent characterisation of when the transfer matrix of a periodic loop model fails to be diagonalisable. This generalises their recent result for non-periodic loop models and provides rigorous methods to justify what has often been assumed in the lattice approach to logarithmic CFT. The philosophy here is one of analysing lattice models with finite size, aiming to demonstrate that non-diagonalisability survives the scaling limit. This is extremely difficult in general (see also the review by Gainutdinov et al ), so it is remarkable that it is even possible to demonstrate this at any level of generality. Quella and Schomerus have prepared an extensive review covering their longstanding collaboration on the logarithmic nature of conformal sigma models on Lie supergroups and their cosets with applications to string theory and AdS/CFT. Beginning with a very welcome overview of Lie superalgebras and their representations, harmonic analysis and cohomological reduction, they then apply these mathematical tools to WZW models on type I Lie supergroups and their homogeneous subspaces. Along the way, deformations are discussed and potential dualities in the corresponding string theories are described. Ruelle provides an exhaustive account of his substantial contributions to the study of the abelian sandpile model. This is a statistical model which has the surprising feature that many correlation functions can be computed exactly, in the bulk and on the boundary, even though the spectrum of conformal weights is largely unknown. Nevertheless, there is much evidence suggesting that its scaling limit is described by an, as yet unknown, c = -2 logarithmic CFT. Semikhatov and Tipunin present their very recent results regarding the construction of logarithmic chiral W-algebra extensions of a fractional level algebra. The idea is that these algebras are the centralisers of a rank-two Nichols algebra which possesses at least one fermionic generator. In turn, these Nichols algebra generators are represented by screening operators which naturally appear in CFT bosonisation. The major advantage of using these generators is that they give strong hints about the representation theory and fusion rules of the chiral algebra. Simmons has contributed an article describing the calculation of various correlation functions in the logarithmic CFT that describes critical percolation. These calculations are interpreted geometrically in a manner that should be familiar to mathematicians studying Schramm-Loewner evolutions and point towards a (largely unexplored) bridge connecting logarithmic CFT with this branch of mathematics. Of course, the field of logarithmic CFT has benefited greatly from the work of many of researchers who are not represented in this special issue. The interested reader will find many links to their work in the bibliographies of the special issue articles and reviews. In summary, logarithmic CFT describes an extension of the incredibly successful methods of rational CFT to a more general setting. This extension is necessary to properly describe many different fundamental phenomena of physical interest. The formalism is moreover highly non-trivial from a mathematical point of view and so logarithmic theories are of significant interest to both physicists and mathematicians. We hope that the collection of articles that follows will serve as an inspiration, and a valuable resource, for both of these communities.

Entropy and complexity analysis of hydrogenic Rydberg atoms

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

Lopez-Rosa, S.; Departamento de Fisica Aplicada II, Universidad de Sevilla, 41012-Sevilla; Toranzo, I. V.

The internal disorder of hydrogenic Rydberg atoms as contained in their position and momentum probability densities is examined by means of the following information-theoretic spreading quantities: the radial and logarithmic expectation values, the Shannon entropy, and the Fisher information. As well, the complexity measures of Cramer-Rao, Fisher-Shannon, and Lopez Ruiz-Mancini-Calvet types are investigated in both reciprocal spaces. The leading term of these quantities is rigorously calculated by use of the asymptotic properties of the concomitant entropic functionals of the Laguerre and Gegenbauer orthogonal polynomials which control the wavefunctions of the Rydberg states in both position and momentum spaces. The associatedmore » generalized Heisenberg-like, logarithmic and entropic uncertainty relations are also given. Finally, application to linear (l= 0), circular (l=n- 1), and quasicircular (l=n- 2) states is explicitly done.« less

Lunar Volatile System Dynamics: Observations Enabled by the Deep Space Gateway

NASA Astrophysics Data System (ADS)

Honniball, C. I.; Lucey, P. G.; Petro, N.; Hurley, D.; Farrell, W.

2018-02-01

A UV spectrometer-imager and IR spectrometer are proposed to solve questions regarding the lunar volatile system. The instrument takes advantage of highly elliptical orbits and the thermal management system of the Deep Space Gateway.

New Decentralized Algorithms for Spacecraft Formation Control Based on a Cyclic Approach

DTIC Science & Technology

2010-06-01

space framework. As metric of performance, a common quadratic norm that weights the performance error and the control effort is traded with the cost...R = DTD, then the metric of interest is (’J)",,, the square of the 2-norm from input w to output z. Given a system G with state space description A ... spaced logarithmic spiral formation. These results are derived for

Experimental Studies on Grooved Double Pipe Heat Exchanger with Different Groove Space

NASA Astrophysics Data System (ADS)

Sunu, P. W.; Arsawan, I. M.; Anakottapary, D. S.; Santosa, I. D. M. C.; Yasa, I. K. A.

2018-01-01

Experimental studies were performed on grooved double pipe heat exchanger (DPHE) with different groove space. The objective of this work is to determine optimal heat transfer parameter especially logarithmic mean temperature difference (LMTD). The document in this paper also provides the total heat observed by the cold fluid. The rectangular grooves were incised on outer surface of tube side with circumferential pattern and two different grooves space, namely 1 mm and 2 mm. The distance between grooves and the grooves high were kept constant, 8 mm and 0.3 mm respectively. The tube diameter is 20 mm and its made of aluminium. The shell is made of acrylic which has 28 mm in diameter. Water is used as the working fluid. Using counter flow scheme, the cold fluid flows in the annulus room of DPHE. The volume flowrate of hot fluid remains constant at 15 lpm. The volume flowrate of cold fluid were varied from 11 lpm to 15 lpm. Based on logarithmic mean temperature difference analysis, the LMTD of 1 mm grooves space was higher compared to that of 2 mm grooves space. The smaller grooves space has more advantage since the recirculating region are increased which essentially cause larger heat transfer enhancement.

Born-Infeld Gravity Revisited

NASA Astrophysics Data System (ADS)

Setare, M. R.; Sahraee, M.

2013-12-01

In this paper, we investigate the behavior of linearized gravitational excitation in the Born-Infeld gravity in AdS3 space. We obtain the linearized equation of motion and show that this higher-order gravity propagate two gravitons, massless and massive, on the AdS3 background. In contrast to the R2 models, such as TMG or NMG, Born-Infeld gravity does not have a critical point for any regular choice of parameters. So the logarithmic solution is not a solution of this model, due to this one cannot find a logarithmic conformal field theory as a dual model for Born-Infeld gravity.

Entanglement dynamics in critical random quantum Ising chain with perturbations

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

Huang, Yichen, E-mail: ychuang@caltech.edu

We simulate the entanglement dynamics in a critical random quantum Ising chain with generic perturbations using the time-evolving block decimation algorithm. Starting from a product state, we observe super-logarithmic growth of entanglement entropy with time. The numerical result is consistent with the analytical prediction of Vosk and Altman using a real-space renormalization group technique. - Highlights: • We study the dynamical quantum phase transition between many-body localized phases. • We simulate the dynamics of a very long random spin chain with matrix product states. • We observe numerically super-logarithmic growth of entanglement entropy with time.

Two Universality Properties Associated with the Monkey Model of Zipf's Law

NASA Astrophysics Data System (ADS)

Perline, Richard; Perline, Ron

2016-03-01

The distribution of word probabilities in the monkey model of Zipf's law is associated with two universality properties: (1) the power law exponent converges strongly to $-1$ as the alphabet size increases and the letter probabilities are specified as the spacings from a random division of the unit interval for any distribution with a bounded density function on $[0,1]$; and (2), on a logarithmic scale the version of the model with a finite word length cutoff and unequal letter probabilities is approximately normally distributed in the part of the distribution away from the tails. The first property is proved using a remarkably general limit theorem for the logarithm of sample spacings from Shao and Hahn, and the second property follows from Anscombe's central limit theorem for a random number of i.i.d. random variables. The finite word length model leads to a hybrid Zipf-lognormal mixture distribution closely related to work in other areas.

The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion

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

Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin

Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-N c master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluonmore » expansion therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of α slog. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of α slog from the coefficients of the fixed order expansion.« less

The analytic structure of non-global logarithms: Convergence of the dressed gluon expansion

DOE PAGES

Larkoski, Andrew J.; Moult, Ian; Neill, Duff Austin

2016-11-15

Non-global logarithms (NGLs) are the leading manifestation of correlations between distinct phase space regions in QCD and gauge theories and have proven a challenge to understand using traditional resummation techniques. Recently, the dressed gluon ex-pansion was introduced that enables an expansion of the NGL series in terms of a “dressed gluon” building block, defined by an all-orders factorization theorem. Here, we clarify the nature of the dressed gluon expansion, and prove that it has an infinite radius of convergence as a solution to the leading logarithmic and large-N c master equation for NGLs, the Banfi-Marchesini-Smye (BMS) equation. The dressed gluonmore » expansion therefore provides an expansion of the NGL series that can be truncated at any order, with reliable uncertainty estimates. In contrast, manifest in the results of the fixed-order expansion of the BMS equation up to 12-loops is a breakdown of convergence at a finite value of α slog. We explain this finite radius of convergence using the dressed gluon expansion, showing how the dynamics of the buffer region, a region of phase space near the boundary of the jet that was identified in early studies of NGLs, leads to large contributions to the fixed order expansion. We also use the dressed gluon expansion to discuss the convergence of the next-to-leading NGL series, and the role of collinear logarithms that appear at this order. Finally, we show how an understanding of the analytic behavior obtained from the dressed gluon expansion allows us to improve the fixed order NGL series using conformal transformations to extend the domain of analyticity. Furthermore, this allows us to calculate the NGL distribution for all values of α slog from the coefficients of the fixed order expansion.« less

PLUTO'S SEASONS: NEW PREDICTIONS FOR NEW HORIZONS

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

Young, L. A.

Since the last Pluto volatile transport models were published in 1996, we have (1) new stellar occultation data from 2002 and 2006-2012 that show roughly twice the pressure as the first definitive occultation from 1988, (2) new information about the surface properties of Pluto, (3) a spacecraft due to arrive at Pluto in 2015, and (4) a new volatile transport model that is rapid enough to allow a large parameter-space search. Such a parameter-space search coarsely constrained by occultation results reveals three broad solutions: a high-thermal inertia, large volatile inventory solution with permanent northern volatiles (PNVs; using the rotational northmore » pole convention); a lower thermal-inertia, smaller volatile inventory solution with exchanges of volatiles between hemispheres and a pressure plateau beyond 2015 (exchange with pressure plateau, EPP); and solutions with still smaller volatile inventories, with exchanges of volatiles between hemispheres and an early collapse of the atmosphere prior to 2015 (exchange with early collapse, EEC). PNV and EPP are favored by stellar occultation data, but EEC cannot yet be definitively ruled out without more atmospheric modeling or additional occultation observations and analysis.« less

A Search for Binary Systems among the Nearest L Dwarfs

NASA Astrophysics Data System (ADS)

Reid, I. Neill; Lewitus, E.; Allen, P. R.; Cruz, Kelle L.; Burgasser, Adam J.

2006-08-01

We have used the Near-Infrared Camera and Multi-Object Spectrometer NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 52 ultracool dwarfs in the immediate solar neighborhood. Nine systems are resolved as binary, with component separations from 1.5 to 15 AU. Based on current theoretical models and empirical bolometric corrections, all systems have components with similar luminosities and, consequently, high mass ratios, q>0.8. Limiting analysis to L dwarfs within 20 pc, the observed binary fraction is 12%+7-3. Applying Bayesian analysis to our data set, we derive a mass-ratio distribution that peaks strongly at unity. Modeling the semimajor axis distribution as a logarithmic Gaussian, the best fit is centered at loga0=0.8 AU (~6.3 AU), with a (logarithmic) width of +/-0.3. The current data are consistent with an overall binary frequency of ~24%. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Noncommuting observables in quantum detection and estimation theory

NASA Technical Reports Server (NTRS)

Helstrom, C. W.

1972-01-01

Basing decisions and estimates on simultaneous approximate measurements of noncommuting observables in a quantum receiver is shown to be equivalent to measuring commuting projection operators on a larger Hilbert space than that of the receiver itself. The quantum-mechanical Cramer-Rao inequalities derived from right logarithmic derivatives and symmetrized logarithmic derivatives of the density operator are compared, and it is shown that the latter give superior lower bounds on the error variances of individual unbiased estimates of arrival time and carrier frequency of a coherent signal. For a suitably weighted sum of the error variances of simultaneous estimates of these, the former yield the superior lower bound under some conditions.

Cross-correlation analysis between Chinese TF contracts and treasury ETF based on high-frequency data

NASA Astrophysics Data System (ADS)

Zhou, Yu; Chen, Shi

2016-02-01

In this paper, we investigate the high-frequency cross-correlation relationship between Chinese treasury futures contracts and treasury ETF. We analyze the logarithmic return of these two price series, from which we can conclude that both return series are not normally distributed and the futures markets have greater volatility. We find significant cross-correlation between these two series. We further confirm the relationship using the DCCA coefficient and the DMCA coefficient. We quantify the long-range cross-correlation with DCCA method, and we further show that the relationship is multifractal. An arbitrage algorithm based on DFA regression with stable return is proposed in the last part.

Vision-Based Navigation and Parallel Computing

DTIC Science & Technology

1990-08-01

33 5.8. Behizad Kamgar-Parsi and Behrooz Karngar-Parsi,"On Problem 5- lving with Hopfield Neural Networks", CAR-TR-462, CS-TR...Second. the hypercube connections support logarithmic implementations of fundamental parallel algorithms. such as grid permutations and scan...the pose space. It also uses a set of virtual processors to represent an orthogonal projection grid , and projections of the six dimensional pose space

Space Mathematics: A Resource for Secondary School Teachers

NASA Technical Reports Server (NTRS)

Kastner, Bernice

1985-01-01

A collection of mathematical problems related to NASA space science projects is presented. In developing the examples and problems, attention was given to preserving the authenticity and significance of the original setting while keeping the level of mathematics within the secondary school curriculum. Computation and measurement, algebra, geometry, probability and statistics, exponential and logarithmic functions, trigonometry, matrix algebra, conic sections, and calculus are among the areas addressed.

Impacts of environmental conditions on the sorption of volatile organic compounds onto tire powder.

PubMed

Oh, Dong I; Nam, Kyongphile; Park, Jae W; Khim, Jee H; Kim, Yong K; Kim, Jae Y

2008-05-01

A series of batch tests were performed and the impacts of environmental conditions and phase change on the sorption of volatile organic compounds (VOCs) were investigated. Benzene, trichloroethylene, tetrachloroethylene, and ethylbenzene were selected as target VOCs. Sorption of VOCs onto tire powder was well demonstrated by a linear-partitioning model. Water-tire partition coefficients of VOCs (not tested in this study) could be estimated using a logarithmic relationship between observed water-tire partition coefficients and octanol-water partition coefficients of the VOCs tested. The target VOCs did not seem to compete with other VOCs significantly when sorbed onto the tire powder for the range of concentrations tested. The influence of environmental conditions, such as pH and ionic strength also did not seem to be significant. Water-tire partition coefficients of benzene, trichloroethylene, tetrachloroethylene, and ethylbenzene decreased as the sorbent dosage increased. However, they showed stable values when the sorbent dosage was greater than 10 g/L. Air-tire partition coefficient could be extrapolated from Henry's law constants and water-tire partition coefficient of VOCs.

Logarithmic black hole entropy corrections and holographic Rényi entropy

NASA Astrophysics Data System (ADS)

Mahapatra, Subhash

2018-01-01

The entanglement and Rényi entropies for spherical entangling surfaces in CFTs with gravity duals can be explicitly calculated by mapping these entropies first to the thermal entropy on hyperbolic space and then, using the AdS/CFT correspondence, to the Wald entropy of topological black holes. Here we extend this idea by taking into account corrections to the Wald entropy. Using the method based on horizon symmetries and the asymptotic Cardy formula, we calculate corrections to the Wald entropy and find that these corrections are proportional to the logarithm of the area of the horizon. With the corrected expression for the entropy of the black hole, we then find corrections to the Rényi entropies. We calculate these corrections for both Einstein and Gauss-Bonnet gravity duals. Corrections with logarithmic dependence on the area of the entangling surface naturally occur at the order GD^0. The entropic c-function and the inequalities of the Rényi entropy are also satisfied even with the correction terms.

The effect of multiplicity of stellar encounters and the diffusion coefficients in a locally homogeneous three-dimensional stellar medium: Removing the classical divergence

NASA Astrophysics Data System (ADS)

Rastorguev, A. S.; Utkin, N. D.; Chumak, O. V.

2017-08-01

Agekyan's λ-factor that allows for the effect of multiplicity of stellar encounters with large impact parameters has been used for the first time to directly calculate the diffusion coefficients in the phase space of a stellar system. Simple estimates show that the cumulative effect, i.e., the total contribution of distant encounters to the change in the velocity of a test star, given the multiplicity of stellar encounters, is finite, and the logarithmic divergence inherent in the classical description of diffusion is removed, as was shown previously byKandrup using a different, more complex approach. In this case, the expressions for the diffusion coefficients, as in the classical description, contain the logarithm of the ratio of two independent quantities: the mean interparticle distance and the impact parameter of a close encounter. However, the physical meaning of this logarithmic factor changes radically: it reflects not the divergence but the presence of two characteristic length scales inherent in the stellar medium.

SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition

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

Ilgenfritz, Ernst-Michael; Humboldt-Universitaet zu Berlin, Institut fuer Physik, 12489 Berlin; Menz, Christoph

2011-03-01

We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory. In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of themore » associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite size, and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order numerical stochastic perturbation theory.« less

Air-sea exchange and gas-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow

NASA Astrophysics Data System (ADS)

Wu, Z.; Guo, Z.

2017-12-01

We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea gas exchange, and gas-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three- to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea exchange fluxes of gaseous PAHs were estimated to be -54.2 to 107.4 ng m-2 d-1, and was indicative of variations of land-based PAH inputs. The logarithmic gas-particle partition coefficient (logKp) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure, with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH gas-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH gas-particle partitioning deviated more from the modeling Kp for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea exchange. Meanwhile, significant linear regressions between logKp and logKoa (logKsa) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign.

Air-sea exchange and gas-particle partitioning of polycyclic aromatic hydrocarbons over the northwestern Pacific Ocean: Role of East Asian continental outflow.

PubMed

Wu, Zilan; Lin, Tian; Li, Zhongxia; Jiang, Yuqing; Li, Yuanyuan; Yao, Xiaohong; Gao, Huiwang; Guo, Zhigang

2017-11-01

We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea gas exchange, and gas-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea exchange fluxes of gaseous PAHs were estimated to be -54.2-107.4 ng m -2 d -1 , and was indicative of variations of land-based PAH inputs. The logarithmic gas-particle partition coefficient (logK p ) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (logP L 0 ), with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH gas-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH gas-particle partitioning deviated more from the modeling K p for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea exchange. Meanwhile, significant linear regressions between logK p and logK oa (logK sa ) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign. Copyright © 2017 Elsevier Ltd. All rights reserved.

Log-polar mapping-based scale space tracking with adaptive target response

NASA Astrophysics Data System (ADS)

Li, Dongdong; Wen, Gongjian; Kuai, Yangliu; Zhang, Ximing

2017-05-01

Correlation filter-based tracking has exhibited impressive robustness and accuracy in recent years. Standard correlation filter-based trackers are restricted to translation estimation and equipped with fixed target response. These trackers produce an inferior performance when encountered with a significant scale variation or appearance change. We propose a log-polar mapping-based scale space tracker with an adaptive target response. This tracker transforms the scale variation of the target in the Cartesian space into a shift along the logarithmic axis in the log-polar space. A one-dimensional scale correlation filter is learned online to estimate the shift along the logarithmic axis. With the log-polar representation, scale estimation is achieved accurately without a multiresolution pyramid. To achieve an adaptive target response, a variance of the Gaussian function is computed from the response map and updated online with a learning rate parameter. Our log-polar mapping-based scale correlation filter and adaptive target response can be combined with any correlation filter-based trackers. In addition, the scale correlation filter can be extended to a two-dimensional correlation filter to achieve joint estimation of the scale variation and in-plane rotation. Experiments performed on an OTB50 benchmark demonstrate that our tracker achieves superior performance against state-of-the-art trackers.

Electroweak Sudakov logarithms and real gauge-boson radiation in the TeV region

NASA Astrophysics Data System (ADS)

Bell, G.; Kühn, J. H.; Rittinger, J.

2010-12-01

Electroweak radiative corrections give rise to large negative, double-logarithmically enhanced corrections in the TeV region. These are partly compensated by real radiation and, moreover, affected by selecting isospin-non-invariant external states. We investigate the impact of real gauge boson radiation more quantitatively by considering different restricted final state configurations. We consider successively a massive abelian gauge theory, a spontaneously broken SU(2) theory and the electroweak Standard Model. We find that details of the choice of the phase space cuts, in particular whether a fraction of collinear and soft radiation is included, have a strong impact on the relative amount of real and virtual corrections.

Hierarchical random additive process and logarithmic scaling of generalized high order, two-point correlations in turbulent boundary layer flow

NASA Astrophysics Data System (ADS)

Yang, X. I. A.; Marusic, I.; Meneveau, C.

2016-06-01

Townsend [Townsend, The Structure of Turbulent Shear Flow (Cambridge University Press, Cambridge, UK, 1976)] hypothesized that the logarithmic region in high-Reynolds-number wall-bounded flows consists of space-filling, self-similar attached eddies. Invoking this hypothesis, we express streamwise velocity fluctuations in the inertial layer in high-Reynolds-number wall-bounded flows as a hierarchical random additive process (HRAP): uz+=∑i=1Nzai . Here u is the streamwise velocity fluctuation, + indicates normalization in wall units, z is the wall normal distance, and ai's are independently, identically distributed random additives, each of which is associated with an attached eddy in the wall-attached hierarchy. The number of random additives is Nz˜ln(δ /z ) where δ is the boundary layer thickness and ln is natural log. Due to its simplified structure, such a process leads to predictions of the scaling behaviors for various turbulence statistics in the logarithmic layer. Besides reproducing known logarithmic scaling of moments, structure functions, and correlation function [" close="]3/2 uz(x ) uz(x +r ) >, new logarithmic laws in two-point statistics such as uz4(x ) > 1 /2, 1/3, etc. can be derived using the HRAP formalism. Supporting empirical evidence for the logarithmic scaling in such statistics is found from the Melbourne High Reynolds Number Boundary Layer Wind Tunnel measurements. We also show that, at high Reynolds numbers, the above mentioned new logarithmic laws can be derived by assuming the arrival of an attached eddy at a generic point in the flow field to be a Poisson process [Woodcock and Marusic, Phys. Fluids 27, 015104 (2015), 10.1063/1.4905301]. Taken together, the results provide new evidence supporting the essential ingredients of the attached eddy hypothesis to describe streamwise velocity fluctuations of large, momentum transporting eddies in wall-bounded turbulence, while observed deviations suggest the need for further extensions of the model.

Segmented strings in AdS 3

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

Callebaut, Nele; Gubser, Steven S.; Samberg, Andreas

We study segmented strings in flat space and in AdS 3. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In AdS 3, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an AdS 2 subspace of AdS 3. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We studymore » several examples of closed segmented strings in AdS 3 and find an unexpected quasi-periodic behavior. Here, we also work out a WKB analysis of quantum states of yo-yo strings in AdS 5 and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.« less

Segmented strings in AdS 3

DOE PAGES

Callebaut, Nele; Gubser, Steven S.; Samberg, Andreas; ...

2015-11-17

We study segmented strings in flat space and in AdS 3. In flat space, these well known classical motions describe strings which at any instant of time are piecewise linear. In AdS 3, the worldsheet is composed of faces each of which is a region bounded by null geodesics in an AdS 2 subspace of AdS 3. The time evolution can be described by specifying the null geodesic motion of kinks in the string at which two segments are joined. The outcome of collisions of kinks on the worldsheet can be worked out essentially using considerations of causality. We studymore » several examples of closed segmented strings in AdS 3 and find an unexpected quasi-periodic behavior. Here, we also work out a WKB analysis of quantum states of yo-yo strings in AdS 5 and find a logarithmic term reminiscent of the logarithmic twist of string states on the leading Regge trajectory.« less

Entanglement entropy in (3 + 1)-d free U(1) gauge theory

NASA Astrophysics Data System (ADS)

Soni, Ronak M.; Trivedi, Sandip P.

2017-02-01

We consider the entanglement entropy for a free U(1) theory in 3+1 dimensions in the extended Hilbert space definition. By taking the continuum limit carefully we obtain a replica trick path integral which calculates this entanglement entropy. The path integral is gauge invariant, with a gauge fixing delta function accompanied by a Faddeev -Popov determinant. For a spherical region it follows that the result for the logarithmic term in the entanglement, which is universal, is given by the a anomaly coefficient. We also consider the extractable part of the entanglement, which corresponds to the number of Bell pairs which can be obtained from entanglement distillation or dilution. For a spherical region we show that the coefficient of the logarithmic term for the extractable part is different from the extended Hilbert space result. We argue that the two results will differ in general, and this difference is accounted for by a massless scalar living on the boundary of the region of interest.

Implications of improved Higgs mass calculations for supersymmetric models.

PubMed

Buchmueller, O; Dolan, M J; Ellis, J; Hahn, T; Heinemeyer, S; Hollik, W; Marrouche, J; Olive, K A; Rzehak, H; de Vries, K J; Weiglein, G

We discuss the allowed parameter spaces of supersymmetric scenarios in light of improved Higgs mass predictions provided by FeynHiggs 2.10.0. The Higgs mass predictions combine Feynman-diagrammatic results with a resummation of leading and subleading logarithmic corrections from the stop/top sector, which yield a significant improvement in the region of large stop masses. Scans in the pMSSM parameter space show that, for given values of the soft supersymmetry-breaking parameters, the new logarithmic contributions beyond the two-loop order implemented in FeynHiggs tend to give larger values of the light CP-even Higgs mass, [Formula: see text], in the region of large stop masses than previous predictions that were based on a fixed-order Feynman-diagrammatic result, though the differences are generally consistent with the previous estimates of theoretical uncertainties. We re-analyse the parameter spaces of the CMSSM, NUHM1 and NUHM2, taking into account also the constraints from CMS and LHCb measurements of [Formula: see text]and ATLAS searches for [Formula: see text] events using 20/fb of LHC data at 8 TeV. Within the CMSSM, the Higgs mass constraint disfavours [Formula: see text], though not in the NUHM1 or NUHM2.

Recovery of phosphonate surface contaminants from glass using a simple vacuum extractor with a solid-phase microextraction fiber.

PubMed

Groenewold, Gary S; Scott, Jill R; Rae, Catherine

2011-07-04

Recovery of chemical contaminants from fixed surfaces for analysis can be challenging, particularly if it is not possible to acquire a solid sample to be taken to the laboratory. A simple device is described that collects semi-volatile organic compounds from fixed surfaces by creating an enclosed volume over the surface, then generating a modest vacuum. A solid-phase microextraction (SPME) fiber is then inserted into the evacuated volume where it functions to sorb volatilized organic contaminants. The device is based on a syringe modified with a seal that is used to create the vacuum, with a perforable plunger through which the SPME fiber is inserted. The reduced pressure speeds partitioning of the semi-volatile compounds into the gas phase and reduces the boundary layer around the SPME fiber, which enables a fraction of the volatilized organics to partition into the SPME fiber. After sample collection, the SPME fiber is analyzed using conventional gas chromatography/mass spectrometry. The methodology has been used to collect organophosphorus compounds from glass surfaces, to provide a simple test for the functionality of the devices. Thirty minute sampling times (ΔT(vac)) resulted in fractional recovery efficiencies that ranged from 10(-3) to >10(-2), and in absolute terms, collection of low nanograms was demonstrated. Fractional recovery values were positively correlated to the vapor pressure of the compounds being sampled. Fractional recovery also increased with increasing ΔT(vac) and displayed a roughly logarithmic profile, indicating that an operational equilibrium is being approached. Fractional recovery decreased with increasing time between exposure and sampling; however, recordable quantities of the phosphonates could be collected three weeks after exposure. Copyright © 2011 Elsevier B.V. All rights reserved.

Dominance, Information, and Hierarchical Scaling of Variance Space.

ERIC Educational Resources Information Center

Ceurvorst, Robert W.; Krus, David J.

1979-01-01

A method for computation of dominance relations and for construction of their corresponding hierarchical structures is presented. The link between dominance and variance allows integration of the mathematical theory of information with least squares statistical procedures without recourse to logarithmic transformations of the data. (Author/CTM)

Acoustic firearm discharge detection and classification in an enclosed environment

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

Luzi, Lorenzo; Gonzalez, Eric; Bruillard, Paul

2016-05-01

Two different signal processing algorithms are described for detection and classification of acoustic signals generated by firearm discharges in small enclosed spaces. The first is based on the logarithm of the signal energy. The second is a joint entropy. The current study indicates that a system using both signal energy and joint entropy would be able to both detect weapon discharges and classify weapon type, in small spaces, with high statistical certainty.

Time-independent models of asset returns revisited

NASA Astrophysics Data System (ADS)

Gillemot, L.; Töyli, J.; Kertesz, J.; Kaski, K.

2000-07-01

In this study we investigate various well-known time-independent models of asset returns being simple normal distribution, Student t-distribution, Lévy, truncated Lévy, general stable distribution, mixed diffusion jump, and compound normal distribution. For this we use Standard and Poor's 500 index data of the New York Stock Exchange, Helsinki Stock Exchange index data describing a small volatile market, and artificial data. The results indicate that all models, excluding the simple normal distribution, are, at least, quite reasonable descriptions of the data. Furthermore, the use of differences instead of logarithmic returns tends to make the data looking visually more Lévy-type distributed than it is. This phenomenon is especially evident in the artificial data that has been generated by an inflated random walk process.

Time-scale effects on the gain-loss asymmetry in stock indices

NASA Astrophysics Data System (ADS)

Sándor, Bulcsú; Simonsen, Ingve; Nagy, Bálint Zsolt; Néda, Zoltán

2016-08-01

The gain-loss asymmetry, observed in the inverse statistics of stock indices is present for logarithmic return levels that are over 2 % , and it is the result of the non-Pearson-type autocorrelations in the index. These non-Pearson-type correlations can be viewed also as functionally dependent daily volatilities, extending for a finite time interval. A generalized time-window shuffling method is used to show the existence of such autocorrelations. Their characteristic time scale proves to be smaller (less than 25 trading days) than what was previously believed. It is also found that this characteristic time scale has decreased with the appearance of program trading in the stock market transactions. Connections with the leverage effect are also established.

Neutrino masses and their ordering: global data, priors and models

NASA Astrophysics Data System (ADS)

Gariazzo, S.; Archidiacono, M.; de Salas, P. F.; Mena, O.; Ternes, C. A.; Tórtola, M.

2018-03-01

We present a full Bayesian analysis of the combination of current neutrino oscillation, neutrinoless double beta decay and Cosmic Microwave Background observations. Our major goal is to carefully investigate the possibility to single out one neutrino mass ordering, namely Normal Ordering or Inverted Ordering, with current data. Two possible parametrizations (three neutrino masses versus the lightest neutrino mass plus the two oscillation mass splittings) and priors (linear versus logarithmic) are exhaustively examined. We find that the preference for NO is only driven by neutrino oscillation data. Moreover, the values of the Bayes factor indicate that the evidence for NO is strong only when the scan is performed over the three neutrino masses with logarithmic priors; for every other combination of parameterization and prior, the preference for NO is only weak. As a by-product of our Bayesian analyses, we are able to (a) compare the Bayesian bounds on the neutrino mixing parameters to those obtained by means of frequentist approaches, finding a very good agreement; (b) determine that the lightest neutrino mass plus the two mass splittings parametrization, motivated by the physical observables, is strongly preferred over the three neutrino mass eigenstates scan and (c) find that logarithmic priors guarantee a weakly-to-moderately more efficient sampling of the parameter space. These results establish the optimal strategy to successfully explore the neutrino parameter space, based on the use of the oscillation mass splittings and a logarithmic prior on the lightest neutrino mass, when combining neutrino oscillation data with cosmology and neutrinoless double beta decay. We also show that the limits on the total neutrino mass ∑ mν can change dramatically when moving from one prior to the other. These results have profound implications for future studies on the neutrino mass ordering, as they crucially state the need for self-consistent analyses which explore the best parametrization and priors, without combining results that involve different assumptions.

Noise-induced phase space transport in two-dimensional Hamiltonian systems.

PubMed

Pogorelov, I V; Kandrup, H E

1999-08-01

First passage time experiments were used to explore the effects of low amplitude noise as a source of accelerated phase space diffusion in two-dimensional Hamiltonian systems, and these effects were then compared with the effects of periodic driving. The objective was to quantify and understand the manner in which "sticky" chaotic orbits that, in the absence of perturbations, are confined near regular islands for very long times, can become "unstuck" much more quickly when subjected to even very weak perturbations. For both noise and periodic driving, the typical escape time scales logarithmically with the amplitude of the perturbation. For white noise, the details seem unimportant: Additive and multiplicative noise typically have very similar effects, and the presence or absence of a friction related to the noise by a fluctuation-dissipation theorem is also largely irrelevant. Allowing for colored noise can significantly decrease the efficacy of the perturbation, but only when the autocorrelation time, which vanishes for white noise, becomes so large that there is little power at frequencies comparable to the natural frequencies of the unperturbed orbit. Similarly, periodic driving is relatively inefficient when the driving frequency is not comparable to these natural frequencies. This suggests that noise-induced extrinsic diffusion, like modulational diffusion associated with periodic driving, is a resonance phenomenon. The logarithmic dependence of the escape time on amplitude reflects the fact that the time required for perturbed and unperturbed orbits to diverge a given distance scales logarithmically in the amplitude of the perturbation.

Efficient Queries of Stand-off Annotations for Natural Language Processing on Electronic Medical Records.

PubMed

Luo, Yuan; Szolovits, Peter

2016-01-01

In natural language processing, stand-off annotation uses the starting and ending positions of an annotation to anchor it to the text and stores the annotation content separately from the text. We address the fundamental problem of efficiently storing stand-off annotations when applying natural language processing on narrative clinical notes in electronic medical records (EMRs) and efficiently retrieving such annotations that satisfy position constraints. Efficient storage and retrieval of stand-off annotations can facilitate tasks such as mapping unstructured text to electronic medical record ontologies. We first formulate this problem into the interval query problem, for which optimal query/update time is in general logarithm. We next perform a tight time complexity analysis on the basic interval tree query algorithm and show its nonoptimality when being applied to a collection of 13 query types from Allen's interval algebra. We then study two closely related state-of-the-art interval query algorithms, proposed query reformulations, and augmentations to the second algorithm. Our proposed algorithm achieves logarithmic time stabbing-max query time complexity and solves the stabbing-interval query tasks on all of Allen's relations in logarithmic time, attaining the theoretic lower bound. Updating time is kept logarithmic and the space requirement is kept linear at the same time. We also discuss interval management in external memory models and higher dimensions.

Efficient Queries of Stand-off Annotations for Natural Language Processing on Electronic Medical Records

PubMed Central

Luo, Yuan; Szolovits, Peter

2016-01-01

In natural language processing, stand-off annotation uses the starting and ending positions of an annotation to anchor it to the text and stores the annotation content separately from the text. We address the fundamental problem of efficiently storing stand-off annotations when applying natural language processing on narrative clinical notes in electronic medical records (EMRs) and efficiently retrieving such annotations that satisfy position constraints. Efficient storage and retrieval of stand-off annotations can facilitate tasks such as mapping unstructured text to electronic medical record ontologies. We first formulate this problem into the interval query problem, for which optimal query/update time is in general logarithm. We next perform a tight time complexity analysis on the basic interval tree query algorithm and show its nonoptimality when being applied to a collection of 13 query types from Allen’s interval algebra. We then study two closely related state-of-the-art interval query algorithms, proposed query reformulations, and augmentations to the second algorithm. Our proposed algorithm achieves logarithmic time stabbing-max query time complexity and solves the stabbing-interval query tasks on all of Allen’s relations in logarithmic time, attaining the theoretic lower bound. Updating time is kept logarithmic and the space requirement is kept linear at the same time. We also discuss interval management in external memory models and higher dimensions. PMID:27478379

New Approaches to Waterproofing of Space Shuttle Insulating Materials

NASA Technical Reports Server (NTRS)

Blum, Yigal D.; Johnson, Sylvia M.; Chen, Paul

1997-01-01

Future reusable space vehicles will be in service much more frequently than current space shuttles. Therefore, rapid reconditioning of spacecraft will be required. Currently, the waterproofing of space shuttles after each re-entry takes 72 hours and requires substantial labor. In addition, the currently used waterproofing reagent, DiMethylEthoxySilane (DMES), is considered toxic, and ethanol fumes are released during its hydrolytic activation. Consequently, a long time period, which is not acceptable for future operations, is needed to ensure that 0 the excess volatile compounds are removed before further maintenance of the space vehicle can be performed. The objective of this project was to assist NASA Ames in finding improved waterproofing systems by identifying suitable waterproofing agents that can be applied by vapor phase deposition and will be less toxic, bond more rapidly to the insulation material surface, and potentially have higher thermal stability than the DMES system. Several approaches to achieve faster waterproofing with less toxicity were assessed using the following alternatives: Reactive volatile compounds that are rapidly deposited by chemical bonding at the surface and leave no toxic volatiles. Reactive reagents that are the least toxic. Nonvolatile reagents that are very reactive and bond strongly to the insulating material surface. Three specific types of potential reagents were chosen for evaluation in this project: 1. Volatile reagents with Si-Cl functional groups for vapor deposition 2. Volatile reagents with Si-H functional groups for vapor deposition 3. Nonvolatile oligomeric or polymeric reactive siloxanes that are assumed to have higher thermal stability and/or strong bonding to the insulating material. The chemistry involved in the project was targeted at the generation of intermediates having reactive Si-OH bonds for the formation of either volatile species or polymeric species that bond rapidly to the surface and also cure rapidly. We focused on two chemical reactions@-hydrolysis of Si-Cl bonds and catalytic dehydrocoupling of Si-H bonds.

Vapor Intrusion

EPA Pesticide Factsheets

Vapor intrusion occurs when there is a migration of volatile chemicals from contaminated groundwater or soil into an overlying building. Volatile chemicals can emit vapors that may migrate through subsurface soils and into indoor air spaces.

Resummed Differential Cross Sections for Top-Quark Pairs at the LHC.

PubMed

Pecjak, Benjamin D; Scott, Darren J; Wang, Xing; Yang, Li Lin

2016-05-20

We present state of the art resummation predictions for differential cross sections in top-quark pair production at the LHC. They are derived from a formalism which allows the simultaneous resummation of both soft and small-mass logarithms, which endanger the convergence of fixed-order perturbative series in the boosted regime, where the partonic center-of-mass energy is much larger than the mass to the top quark. We combine such a double resummation at next-to-next-to-leading logarithmic^{'} (NNLL^{'}) accuracy with standard soft-gluon resummation at next-to-next-to-leading logarithmic accuracy and with next-to-leading-order calculations, so that our results are applicable throughout the whole phase space. We find that the resummation effects on the differential distributions are significant, bringing theoretical predictions into better agreement with experimental data compared to fixed-order calculations. Moreover, such effects are not well described by the next-to-next-to-leading-order approximation of the resummation formula, especially in the high-energy tails of the distributions, highlighting the importance of all-orders resummation in dedicated studies of boosted top production.

Fragmentation functions beyond fixed order accuracy

NASA Astrophysics Data System (ADS)

Anderle, Daniele P.; Kaufmann, Tom; Stratmann, Marco; Ringer, Felix

2017-03-01

We give a detailed account of the phenomenology of all-order resummations of logarithmically enhanced contributions at small momentum fraction of the observed hadron in semi-inclusive electron-positron annihilation and the timelike scale evolution of parton-to-hadron fragmentation functions. The formalism to perform resummations in Mellin moment space is briefly reviewed, and all relevant expressions up to next-to-next-to-leading logarithmic order are derived, including their explicit dependence on the factorization and renormalization scales. We discuss the details pertinent to a proper numerical implementation of the resummed results comprising an iterative solution to the timelike evolution equations, the matching to known fixed-order expressions, and the choice of the contour in the Mellin inverse transformation. First extractions of parton-to-pion fragmentation functions from semi-inclusive annihilation data are performed at different logarithmic orders of the resummations in order to estimate their phenomenological relevance. To this end, we compare our results to corresponding fits up to fixed, next-to-next-to-leading order accuracy and study the residual dependence on the factorization scale in each case.

Adjustments for the display of quantized ion channel dwell times in histograms with logarithmic bins.

PubMed

Stark, J A; Hladky, S B

2000-02-01

Dwell-time histograms are often plotted as part of patch-clamp investigations of ion channel currents. The advantages of plotting these histograms with a logarithmic time axis were demonstrated by, J. Physiol. (Lond.). 378:141-174), Pflügers Arch. 410:530-553), and, Biophys. J. 52:1047-1054). Sigworth and Sine argued that the interpretation of such histograms is simplified if the counts are presented in a manner similar to that of a probability density function. However, when ion channel records are recorded as a discrete time series, the dwell times are quantized. As a result, the mapping of dwell times to logarithmically spaced bins is highly irregular; bins may be empty, and significant irregularities may extend beyond the duration of 100 samples. Using simple approximations based on the nature of the binning process and the transformation rules for probability density functions, we develop adjustments for the display of the counts to compensate for this effect. Tests with simulated data suggest that this procedure provides a faithful representation of the data.

EOS Interpolation and Thermodynamic Consistency

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

Gammel, J. Tinka

2015-11-16

As discussed in LA-UR-08-05451, the current interpolator used by Grizzly, OpenSesame, EOSPAC, and similar routines is the rational function interpolator from Kerley. While the rational function interpolator is well-suited for interpolation on sparse grids with logarithmic spacing and it preserves monotonicity in 1-d, it has some known problems.

Zero energy resonance and the logarithmically slow decay of unstable multilevel systems

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

Miyamoto, Manabu

2006-08-15

The long time behavior of the reduced time evolution operator for unstable multilevel systems is studied based on the N-level Friedrichs model in the presence of a zero energy resonance. The latter means the divergence of the resolvent at zero energy. Resorting to the technique developed by Jensen and Kato [Duke Math. J. 46, 583 (1979)], the zero energy resonance of this model is characterized by the zero energy eigenstate that does not belong to the Hilbert space. It is then shown that for some kinds of the rational form factors the logarithmically slow decay proportional to (log t){sup -1}more » of the reduced time evolution operator can be realized.« less

International Coordination of Lunar Polar Volatiles Exploration

NASA Astrophysics Data System (ADS)

Gruener, J. E.; Suzuki, N. H.; Carpenter, J. D.

2015-10-01

The International Space Exploration Coordination Group (ISECG) has established a study team to coordinate the worldwide interest in lunar polar volatiles, and in particular water ice, in an effort to stimulate cooperation and collaboration.

Potential of derived lunar volatiles for life support

NASA Technical Reports Server (NTRS)

Bula, R. J.; Wittenberg, L. J.; Tibbitts, T. W.; Kulcinski, G. L.

1992-01-01

The lunar regolith contains small quantities of solar wind implanted volatile compounds that have vital, basic uses for maintaining life support systems of lunar or space settlements. Recent proposals to utilize the helium-3 isotope (He-3) derived from the lunar regolith as a fuel for fusion reactors would result in the availability of large quantities of other lunar volatile compounds. The quantities obtained would provide the annual life support replacement requirements of 1150 to 23,000 inhabitants per ton of He-3 recovered, depending on the volatile compound. Utilization of the lunar volatile compounds for life support depends on the costs, in terms of materials and energy, associated with their extraction from the lunar regolith as compared to the delivery costs of these compounds from Earth resources. Considering today's conservative estimated transportation costs ($10,000 dollars per kilogram) and regolith mining costs ($5 dollars per ton), the life support replacement requirements could be more economically supplied by recovering the lunar volatile compounds than transporting these materials from Earth resources, even before He-3 will be utilized as a fusion fuel. In addition, availability of lunar volatile compounds could have a significant cost impact on maintaining the life support systems of the space station and a Mars base.

Characterization of DBD Plasma Actuators Performance Without External Flow - Part I: Thrust-Voltage Quadratic Relationship in Logarithmic Space for Sinusoidal Excitation

NASA Technical Reports Server (NTRS)

Ashpis, David E.; Laun, Matthew C.

2016-01-01

Results of characterization of Dielectric Barrier Discharge (DBD) plasma actuators without external flow are presented. The results include aerodynamic and electric performance of the actuators without external flow for different geometrical parameters, dielectric materials and applied voltage level and wave form.

Micromorphic approach for gradient-extended thermo-elastic-plastic solids in the logarithmic strain space

NASA Astrophysics Data System (ADS)

Aldakheel, Fadi

2017-11-01

The coupled thermo-mechanical strain gradient plasticity theory that accounts for microstructure-based size effects is outlined within this work. It extends the recent work of Miehe et al. (Comput Methods Appl Mech Eng 268:704-734, 2014) to account for thermal effects at finite strains. From the computational viewpoint, the finite element design of the coupled problem is not straightforward and requires additional strategies due to the difficulties near the elastic-plastic boundaries. To simplify the finite element formulation, we extend it toward the micromorphic approach to gradient thermo-plasticity model in the logarithmic strain space. The key point is the introduction of dual local-global field variables via a penalty method, where only the global fields are restricted by boundary conditions. Hence, the problem of restricting the gradient variable to the plastic domain is relaxed, which makes the formulation very attractive for finite element implementation as discussed in Forest (J Eng Mech 135:117-131, 2009) and Miehe et al. (Philos Trans R Soc A Math Phys Eng Sci 374:20150170, 2016).

SOLVENT - Simultaneous Observations of the Lunar Volatile EnvironmeNT

NASA Astrophysics Data System (ADS)

Livengood, T. A.; Anderson, C. M.; Chin, G.; Cohen, B.; Feaga, L.; Hewagama, T.; Protopapa, S.; Racette, P.

2018-02-01

SOLVENT will make Simultaneous Observations of the Lunar Volatile EnviornmeNT in complementary wavelength regimes, to measure the abundance of water and hydroxyl in the illuminated lunar surface and in the free space above it.

The development and testing of a volatile organics concentrator for use in monitoring Space Station water quality

NASA Technical Reports Server (NTRS)

Bodek, Itamar; Ehntholt, Daniel J.; Stolki, Thomas J.; Trabanino, Rudy; Hinsdale, Lloyd; Webb, Johanna; Sauer, Richard L.

1992-01-01

The Volatile Organics Concentrator (VOC) system, designed to attach to a gas chromatograph/mass spectrometer (GC/MS) for the analyses of volatile organic compounds in water on Space Station Freedom, is described. Organic volatiles are collected and concentrated in the VOC by means of two primary solid sorbent tubes and desorbed into the GC/MS system. The paper describes the results of testing the VOC breadboard using a GC/MS system. Evaluations performed on 39 organic compounds recovered from water samples were compared with data for these compounds using direct injection/GC/MS and purge and trap/GC/MS procedures. The results demonstrate that the VOC/GC/MS system's detection limits for the 39 compounds analyzed are comparable to those of the EPA Method 524.2, and for many compounds reaching a factor of 5 lower.

Phase space gradient of dissipated work and information: A role of relative Fisher information

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

Yamano, Takuya, E-mail: yamano@amy.hi-ho.ne.jp

2013-11-15

We show that an information theoretic distance measured by the relative Fisher information between canonical equilibrium phase densities corresponding to forward and backward processes is intimately related to the gradient of the dissipated work in phase space. We present a universal constraint on it via the logarithmic Sobolev inequality. Furthermore, we point out that a possible expression of the lower bound indicates a deep connection in terms of the relative entropy and the Fisher information of the canonical distributions.

A Lower Bound for the Norm of the Solution of a Nonlinear Volterra Equation in One-Dimensional Viscoelasticity.

DTIC Science & Technology

1980-12-09

34, Symp. on Non-well-posed Problems and Logarithmic Convexity (Lecture Notes on Math. #316), pp. 31-5h, Springer, 1973. 3. Greenberg , J.M., MacCamy, R.C...34Continuous Data Dependence for an Abstract Volterra Integro- Differential Equation in Hilbert Space with Applications to Viscoelasticity", Annali Scuola... Hilbert Space", to appear in the J. Applicable Analysis. 8. Slemrod, M., "Instability of Steady Shearing Flows in a Nonlinear Viscoelastic Fluid", Arch

The advantages of logarithmically scaled data for electromagnetic inversion

NASA Astrophysics Data System (ADS)

Wheelock, Brent; Constable, Steven; Key, Kerry

2015-06-01

Non-linear inversion algorithms traverse a data misfit space over multiple iterations of trial models in search of either a global minimum or some target misfit contour. The success of the algorithm in reaching that objective depends upon the smoothness and predictability of the misfit space. For any given observation, there is no absolute form a datum must take, and therefore no absolute definition for the misfit space; in fact, there are many alternatives. However, not all misfit spaces are equal in terms of promoting the success of inversion. In this work, we appraise three common forms that complex data take in electromagnetic geophysical methods: real and imaginary components, a power of amplitude and phase, and logarithmic amplitude and phase. We find that the optimal form is logarithmic amplitude and phase. Single-parameter misfit curves of log-amplitude and phase data for both magnetotelluric and controlled-source electromagnetic methods are the smoothest of the three data forms and do not exhibit flattening at low model resistivities. Synthetic, multiparameter, 2-D inversions illustrate that log-amplitude and phase is the most robust data form, converging to the target misfit contour in the fewest steps regardless of starting model and the amount of noise added to the data; inversions using the other two data forms run slower or fail under various starting models and proportions of noise. It is observed that inversion with log-amplitude and phase data is nearly two times faster in converging to a solution than with other data types. We also assess the statistical consequences of transforming data in the ways discussed in this paper. With the exception of real and imaginary components, which are assumed to be Gaussian, all other data types do not produce an expected mean-squared misfit value of 1.00 at the true model (a common assumption) as the errors in the complex data become large. We recommend that real and imaginary data with errors larger than 10 per cent of the complex amplitude be withheld from a log-amplitude and phase inversion rather than retaining them with large error-bars.

Scaling of Rényi entanglement entropies of the free fermi-gas ground state: a rigorous proof.

PubMed

Leschke, Hajo; Sobolev, Alexander V; Spitzer, Wolfgang

2014-04-25

In a remarkable paper [Phys. Rev. Lett. 96, 100503 (2006)], Gioev and Klich conjectured an explicit formula for the leading asymptotic growth of the spatially bipartite von Neumann entanglement entropy of noninteracting fermions in multidimensional Euclidean space at zero temperature. Based on recent progress by one of us (A. V. S.) in semiclassical functional calculus for pseudodifferential operators with discontinuous symbols, we provide here a complete proof of that formula and of its generalization to Rényi entropies of all orders α>0. The special case α=1/2 is also known under the name logarithmic negativity and often considered to be a particularly useful quantification of entanglement. These formulas exhibiting a "logarithmically enhanced area law" have been used already in many publications.

Apatite-Melt Partitioning of Volatiles in Basaltic Systems: Implications for Determining Volatile Abundances in Planetary Bodies from Apatite

NASA Technical Reports Server (NTRS)

McCubbin, F. M.

2017-01-01

Apatite [Ca5(PO4)3(F,Cl,OH)] is present in a wide range of planetary materials, and due to the presence of volatiles within its crystal structure (X-site), many recent studies have attempted to use apatite to constrain the volatile contents of planetary magmas and mantle sources [i.e., 1]. Experimental studies have investigated the apatite-melt partitioning behavior of F, Cl, and OH in basaltic systems [e.g., 2- 3], reporting that apatite-melt partitioning of volatiles is best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, exchange coefficients may vary as a function of temperature, pressure, melt composition, and/or oxygen fugacity. Furthermore, exchange coefficients may vary in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite [3]. In these regions of ternary space, we anticipate that crystal chemistry could influence partitioning behavior. Consequently, we conducted experiments to investigate the effect of apatite crystal chemistry on apatite-melt partitioning of F, Cl, and OH.

The Volatility of Data Space: Topology Oriented Sensitivity Analysis

PubMed Central

Du, Jing; Ligmann-Zielinska, Arika

2015-01-01

Despite the difference among specific methods, existing Sensitivity Analysis (SA) technologies are all value-based, that is, the uncertainties in the model input and output are quantified as changes of values. This paradigm provides only limited insight into the nature of models and the modeled systems. In addition to the value of data, a potentially richer information about the model lies in the topological difference between pre-model data space and post-model data space. This paper introduces an innovative SA method called Topology Oriented Sensitivity Analysis, which defines sensitivity as the volatility of data space. It extends SA into a deeper level that lies in the topology of data. PMID:26368929

Space exploration and the history of solar-system volatiles

NASA Technical Reports Server (NTRS)

Fanale, F. P.

1976-01-01

The thermochemical history of volatile substances in all solar-system planets, satellites, and planetoids is discussed extensively. The volatiles are viewed as an interface between the abiotic and biotic worlds and as a key to the history of bodies of the solar system. A flowsheet of processes and states is exhibited. Differences in bulk volatiles distribution between the planetary bodies and between the interior, surface, and atmosphere of each body are considered, as well as sinks for volatiles in degassing. The volatiles-rich Jovian and Saturnian satellites, the effect of large-planet magnetosphere sweeps on nearby satellites, volatiles of asteroids and comets, and the crucial importance of seismic, gravity, and libration data are treated. A research program encompassing analysis of the elemental and isotopic composition of rare gas in atmospheres, assay of volatiles-containing phases in regoliths, and examination of present or past atmospheric escape/accretion processes is recommended.

Using the Logarithm of Odds to Define a Vector Space on Probabilistic Atlases

PubMed Central

Pohl, Kilian M.; Fisher, John; Bouix, Sylvain; Shenton, Martha; McCarley, Robert W.; Grimson, W. Eric L.; Kikinis, Ron; Wells, William M.

2007-01-01

The Logarithm of the Odds ratio (LogOdds) is frequently used in areas such as artificial neural networks, economics, and biology, as an alternative representation of probabilities. Here, we use LogOdds to place probabilistic atlases in a linear vector space. This representation has several useful properties for medical imaging. For example, it not only encodes the shape of multiple anatomical structures but also captures some information concerning uncertainty. We demonstrate that the resulting vector space operations of addition and scalar multiplication have natural probabilistic interpretations. We discuss several examples for placing label maps into the space of LogOdds. First, we relate signed distance maps, a widely used implicit shape representation, to LogOdds and compare it to an alternative that is based on smoothing by spatial Gaussians. We find that the LogOdds approach better preserves shapes in a complex multiple object setting. In the second example, we capture the uncertainty of boundary locations by mapping multiple label maps of the same object into the LogOdds space. Third, we define a framework for non-convex interpolations among atlases that capture different time points in the aging process of a population. We evaluate the accuracy of our representation by generating a deformable shape atlas that captures the variations of anatomical shapes across a population. The deformable atlas is the result of a principal component analysis within the LogOdds space. This atlas is integrated into an existing segmentation approach for MR images. We compare the performance of the resulting implementation in segmenting 20 test cases to a similar approach that uses a more standard shape model that is based on signed distance maps. On this data set, the Bayesian classification model with our new representation outperformed the other approaches in segmenting subcortical structures. PMID:17698403

Sources and production of organic aerosol in Mexico City: insights from the combination of a chemical transport model (PMCAMx-2008) and measurements during MILAGRO

NASA Astrophysics Data System (ADS)

Tsimpidi, A. P.; Karydis, V. A.; Zavala, M.; Lei, W.; Bei, N.; Molina, L.; Pandis, S. N.

2011-06-01

Urban areas are large sources of organic aerosols and their precursors. Nevertheless, the contributions of primary (POA) and secondary organic aerosol (SOA) to the observed particulate matter levels have been difficult to quantify. In this study the three-dimensional chemical transport model PMCAMx-2008 is used to investigate the temporal and geographic variability of organic aerosol in the Mexico City Metropolitan Area (MCMA) during the MILAGRO campaign that took place in the spring of 2006. The organic module of PMCAMx-2008 includes the recently developed volatility basis-set framework in which both primary and secondary organic components are assumed to be semi-volatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The MCMA emission inventory is modified and the POA emissions are distributed by volatility based on dilution experiments. The model predictions are compared with observations from four different types of sites, an urban (T0), a suburban (T1), a rural (T2), and an elevated site in Pico de Tres Padres (PTP). The performance of the model in reproducing organic mass concentrations in these sites is encouraging. The average predicted PM1 organic aerosol (OA) concentration in T0, T1, and T2 is 18 μg m-3, 11.7 μg m-3, and 10.5 μg m-3 respectively, while the corresponding measured values are 17.2 μg m-3, 11 μg m-3, and 9 μg m-3. The average predicted locally-emitted primary OA concentrations, 4.4 μg m-3 at T0, 1.2 μg m-3 at T1 and 1.7 μg m-3 at PTP, are in reasonably good agreement with the corresponding PMF analysis estimates based on the Aerosol Mass Spectrometer (AMS) observations of 4.5, 1.3, and 2.9 μg m-3 respectively. The model reproduces reasonably well the average oxygenated OA (OOA) levels in T0 (7.5 μg m-3 predicted versus 7.5 μg m-3 measured), in T1 (6.3 μg m-3 predicted versus 4.6 μg m-3 measured) and in PTP (6.6 μg m-3 predicted versus 5.9 μg m-3 measured). The rest of the OA mass (6.1 μg m-3 and 4.2 μg m-3 in T0 and T1 respectively) is assumed to originate from biomass burning activities and is introduced to the model as part of the boundary conditions. Inside Mexico City (at T0), the locally-produced OA is predicted to be on average 60 % locally-emitted primary (POA), 6 % semi-volatile (S-SOA) and intermediate volatile (I-SOA) organic aerosol, and 34 % traditional SOA from the oxidation of VOCs (V-SOA). The average contributions of the OA components to the locally-produced OA for the entire modelling domain are predicted to be 32 % POA, 10 % S-SOA and I-SOA, and 58 % V-SOA. The long range transport from biomass burning activities and other sources in Mexico is predicted to contribute on average almost as much as the local sources during the MILAGRO period.

Acid Volatile Sulfides and Simultaneously Extracted Copper, Lead, and Zinc in Sediments of Sinclair Inlet, Washington

DTIC Science & Technology

1993-09-01

to Doug Vaught, J. Towell, and Eric Schlierman of Puget Sound Naval Shipyard for providing laboratory space, equipment, and logistical support for the...availability and mobility of toxic metal contamination in the sediments of Sinclair Inlet, Puget Sound , Washington, acid volatile sulfide (AVS) and... Puget Sound , Washington ........ 1 2. Apparatus used for measuring acid volatile sulfides ........................... 5 3. Sulfide electrode

KSC-2013-3979

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3990

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, Ellen Stofan, the agency's chief scientist. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3977

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

A study of volatile contaminants in recovered water

NASA Technical Reports Server (NTRS)

Mckee, H. C.; Marek, R., Jr.

1972-01-01

The recovery and reuse of water during long term space flight is discussed. Particular attention was given to obtaining basic information on the volatile impurities in urine samples and in water recovered from urine by distillation. Data also cover laboratory distillation tests to determine the nature and extent of volatile constituents in the distillate and an evaluation of possible problems in distillation due to iodine used for control of microbial contamination. Efforts made to develop design criteria for distillation equipment to minimize the problems of volatile contaminants various methods which might be used for purification subsequent to recovery are included.

Computing with volatile memristors: an application of non-pinched hysteresis

NASA Astrophysics Data System (ADS)

Pershin, Y. V.; Shevchenko, S. N.

2017-02-01

The possibility of in-memory computing with volatile memristive devices, namely, memristors requiring a power source to sustain their memory, is demonstrated theoretically. We have adopted a hysteretic graphene-based field emission structure as a prototype of a volatile memristor, which is characterized by a non-pinched hysteresis loop. A memristive model of the structure is developed and used to simulate a polymorphic circuit implementing stateful logic gates, such as the material implication. Specific regions of parameter space realizing useful logic functions are identified. Our results are applicable to other realizations of volatile memory devices, such as certain NEMS switches.

The history of Martian volatiles

NASA Astrophysics Data System (ADS)

Jakosky, Bruce M.; Jones, John H.

The behavior of water and other volatiles on Mars is key to understanding the evolution of the climate. The early climate played a fundamental role in producing the observed surface morphology and possibly in enabling the existence of an early biosphere. Geochemical and isotopic data can be used to infer the history of volatiles. On the basis of the isotopic data from the atmosphere and from components of the surface (as measured in meteorites that come from Mars), there appear to be at least two reservoirs of volatiles, one that has undergone exchange with the atmosphere and has been isotopically fractionated, and a second that is unfractionated and may represent juvenile gases. The fractionation of the atmospheric component has occurred primarily through the escape of gas to space. In addition, the atmospheric gases have mixed substantially with crustal reservoirs of volatiles. Such exchange may have occurred in aqueous or hydrothermal environments. The history of escape to space, as driven by the properties of the Sun through time, is consistent with the surface geomorphology. Together, they suggest an early environment that was substantially different from the present one and the evolution through time to a colder, dryer climate.

Momentum-space resummation for transverse observables and the Higgs p ⊥ at N3LL+NNLO

NASA Astrophysics Data System (ADS)

Bizoń, Wojciech; Monni, Pier Francesco; Re, Emanuele; Rottoli, Luca; Torrielli, Paolo

2018-02-01

We present an approach to the momentum-space resummation of global, recursively infrared and collinear safe observables that can vanish away from the Sudakov region. We focus on the hadro-production of a generic colour singlet, and we consider the class of observables that depend only upon the total transverse momentum of the radiation, prime examples being the transverse momentum of the singlet, and ϕ ∗ in Drell-Yan pair production. We derive a resummation formula valid up to next-to-next-to-next-to-leading-logarithmic accuracy for the considered class of observables. We use this result to compute state-of-the-art predictions for the Higgs-boson transverse-momentum spectrum at the LHC at next-to-next-to-next-to-leading-logarithmic accuracy matched to fixed next-to-next-to-leading order. Our resummation formula reduces exactly to the customary resummation performed in impact-parameter space in the known cases, and it also predicts the correct power-behaved scaling of the cross section in the limit of small value of the observable. We show how this formalism is efficiently implemented by means of Monte Carlo techniques in a fully exclusive generator that allows one to apply arbitrary cuts on the Born variables for any colour singlet, as well as to automatically match the resummed results to fixed-order calculations.

Evaluation of Organic Aerosol Formation and Apportionment in a polluted Megacity

NASA Astrophysics Data System (ADS)

Tsimpidi, A. P.; Karydis, V. A.; Zavala, M.; Lei, W.; Decarlo, P. F.; Ulbrich, I.; Jimenez, J. L.; Molina, L. T.; Pandis, S. N.

2009-04-01

Pollution from megacities and large urban areas is important not only for local effects on health, visibility, and ecosystems but also because of their collective influence on atmospheric chemistry and radiative forcing in regional and global scale. Organic species account for a large fraction of the submicron aerosol mass at most megacities. Urban areas are large sources of organic aerosols and their precursors. Nevertheless, the contributions of primary (POA) and secondary organic aerosol (SOA) have been difficult to quantify. In this study, new primary and secondary organic aerosol modules were added to PMCAMx, a three dimensional chemical transport model (Gaydos et al., 2007). The new modeling framework is based on the volatility basis-set approach (Lane et al., 2007): both primary and secondary organic components are assumed to be semivolatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The emission inventory is modified and the POA emissions are distributed by volatility based on dilution experiments (Robinson et al., 2007). PMCAMx is applied in the Mexico City Metropolitan Area during April 2003 and March 2006. The model predictions are compared with Aerodyne's Aerosol Mass Spectrometer (AMS) observations from the MCMA and MILAGRO campaigns respectively. Furthermore, the predicted concentrations over Mexico City are compared against measurements from a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) which was onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign (DeCarlo et al., 2008). The organic aerosol (OA) to CO ratio is used as an indicator in order to evaluate the photo-oxidation of the predicted OA after its horizontal and vertical advection. References Gaydos, T.M.; Pinder, R.W.; Koo, B.; Fahey, K.M.; Pandis, S.N., 2007. Development and application of a three-dimensional aerosol chemical transport model, PMCAMx. Atmospheric Environment 41, 2594-2611. Lane, T.E.; Donahue, N.M.; Pandis, S.N. 2008. Simulating Secondary Organic Aerosol Formation using the Votality Basis-Set Approach in a Chemical Transport Model, Atmospheric Environment 42, 7439-7451 Robinson, A.L.; Donahue, N.M.; Shrivastava, M.K.; Weitkamp, E.A.; Sage, A.M.; Grieshop, A.P.; Lane, T.E.; Pandis, S.N.; Pierce, J.R., 2007. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 315, 1259-1262. DeCarlo, P.F.; Dunlea, E.J., Kimmel,et al., 2008. Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign, Atmos. Chem. Phys., 8, 4027-4048.

Results from On-Orbit Testing of the Fram Memory Test Experiment on the Fastsat Micro-Satellite

NASA Technical Reports Server (NTRS)

MacLeod, Todd C.; Sims, W. Herb; Varnavas, Kosta A.; Ho, Fat D.

2011-01-01

NASA is planning on going beyond Low Earth orbit with manned exploration missions. The radiation environment for most Low Earth orbit missions is harsher than at the Earth's surface but much less harsh than deep space. Development of new electronics is needed to meet the requirements of high performance, radiation tolerance, and reliability. The need for both Volatile and Non-volatile memory has been identified. Emerging Non-volatile memory technologies (FRAM, C-RAM,M-RAM, R-RAM, Radiation Tolerant FLASH, SONOS, etc.) need to be investigated for use in Space missions. An opportunity arose to fly a small memory experiment on a high inclination satellite (FASTSAT). An off-the-shelf 512K Ramtron FRAM was chosen to be tested in the experiment.

Time and Space Efficient Algorithms for Two-Party Authenticated Data Structures

NASA Astrophysics Data System (ADS)

Papamanthou, Charalampos; Tamassia, Roberto

Authentication is increasingly relevant to data management. Data is being outsourced to untrusted servers and clients want to securely update and query their data. For example, in database outsourcing, a client's database is stored and maintained by an untrusted server. Also, in simple storage systems, clients can store very large amounts of data but at the same time, they want to assure their integrity when they retrieve them. In this paper, we present a model and protocol for two-party authentication of data structures. Namely, a client outsources its data structure and verifies that the answers to the queries have not been tampered with. We provide efficient algorithms to securely outsource a skip list with logarithmic time overhead at the server and client and logarithmic communication cost, thus providing an efficient authentication primitive for outsourced data, both structured (e.g., relational databases) and semi-structured (e.g., XML documents). In our technique, the client stores only a constant amount of space, which is optimal. Our two-party authentication framework can be deployed on top of existing storage applications, thus providing an efficient authentication service. Finally, we present experimental results that demonstrate the practical efficiency and scalability of our scheme.

Logarithmic compression methods for spectral data

DOEpatents

Dunham, Mark E.

2003-01-01

A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

Parametric State Space Structuring

NASA Technical Reports Server (NTRS)

Ciardo, Gianfranco; Tilgner, Marco

1997-01-01

Structured approaches based on Kronecker operators for the description and solution of the infinitesimal generator of a continuous-time Markov chains are receiving increasing interest. However, their main advantage, a substantial reduction in the memory requirements during the numerical solution, comes at a price. Methods based on the "potential state space" allocate a probability vector that might be much larger than actually needed. Methods based on the "actual state space", instead, have an additional logarithmic overhead. We present an approach that realizes the advantages of both methods with none of their disadvantages, by partitioning the local state spaces of each submodel. We apply our results to a model of software rendezvous, and show how they reduce memory requirements while, at the same time, improving the efficiency of the computation.

KSC-2013-3978

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by Dr. Jim Green, the agency's Planetary Science director. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3985

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, John Grunsfeld, the agency's associate administrator for the Science Mission Directorate. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3986

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, John Grunsfeld, the agency's associate administrator for the Science Mission Directorate. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

Analysis of volatile components from Melipona beecheii geopropolis from Southeast Mexico by headspace solid-phase microextraction.

PubMed

Torres-González, Ahira; López-Rivera, Paulina; Duarte-Lisci, Georgina; López-Ramírez, Ángel; Correa-Benítez, Adriana; Rivero-Cruz, J Fausto

2016-01-01

A head space solid-phase microextraction method combined with gas chromatography-mass spectrometry was developed and optimised to extract and analyse volatile compounds of Melipona beecheii geopropolis. Seventy-three constituents were identified using this technique in the sample of geopropolis collected. The main compounds detected include β-fenchene (14.53-15.45%), styrene (8.72-9.98%), benzaldehyde (7.44-7.82%) and the most relevant volatile components presents at high level in the geopropolis were terpenoids (58.17%).

Evaluation of the Volatility Basis-Set Approach for Modeling Primary and Secondary Organic Aerosol in the Mexico City Metropolitan Area

NASA Astrophysics Data System (ADS)

Tsimpidi, A. P.; Karydis, V. A.; Pandis, S. N.; Zavala, M.; Lei, W.; Molina, L. T.

2007-12-01

Anthropogenic air pollution is an increasingly serious problem for public health, agriculture, and global climate. Organic material (OM) contributes ~ 20-50% to the total fine aerosol mass at continental mid-latitudes. Although OM accounts for a large fraction of PM2.5 concentration worldwide, the contributions of primary and secondary organic aerosol have been difficult to quantify. In this study, new primary and secondary organic aerosol modules were added to PMCAMx, a three dimensional chemical transport model (Gaydos et al., 2007), for use with the SAPRC99 chemistry mechanism (Carter, 2000; ENVIRON, 2006) based on recent smog chamber studies (Robinson et al., 2007). The new modeling framework is based on the volatility basis-set approach (Lane et al., 2007): both primary and secondary organic components are assumed to be semivolatile and photochemically reactive and are distributed in logarithmically spaced volatility bins. The emission inventory, which uses as starting point the MCMA 2004 official inventory (CAM, 2006), is modified and the primary organic aerosol (POA) emissions are distributed by volatility based on dilution experiments (Robinson et al., 2007). Sensitivity tests where POA is considered as nonvolatile and POA and SOA as chemically reactive are also described. In all cases PMCAMx is applied in the Mexico City Metropolitan Area during March 2006. The modeling domain covers a 180x180x6 km region in the MCMA with 3x3 km grid resolution. The model predictions are compared with Aerodyne's Aerosol Mass Spectrometry (AMS) observations from the MILAGRO Campaign. References Robinson, A. L.; Donahue, N. M.; Shrivastava, M. K.; Weitkamp, E. A.; Sage, A. M.; Grieshop, A. P.; Lane, T. E.; Pandis, S. N.; Pierce, J. R., 2007. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 315, 1259-1262. Gaydos, T. M.; Pinder, R. W.; Koo, B.; Fahey, K. M.; Pandis, S. N., 2007. Development and application of a three- dimensional aerosol chemical transport model, PMCAMx. Atmospheric Environment 41, 2594-2611. Carter, W.P.L., 2000. Programs and Files Implementing the SAPRC-99 Mechanism and its Associates Emissions Processing Procedures for Models-3 and Other Regional Models. January 31, 2000. http://pah.cert.ucr.edu/~carter/SAPRC99.htm. Environ, 2006. User's guide to the comprehensive air quality model with extensions (CAMx). Version 4.30. Report prepared by ENVIRON International Corporation, Novato, CA. Lane, T.E.; Donahue, N. M.; Pandis, S. N. 2007. Simulating Secondary Organic Aerosol Formation using the Votality Basis-Set Approach in a Chemical Transport Model, in preperation. CAM (Comision Ambiental Metropolitana) 2006: Inventario de Emisiones 2004 de la Zona Metropolitana del Valle de Mexico, Mexico. Robinson, A. L.; Donahue, N. M.; Shrivastava, M. K.; Weitkamp, E. A.; Sage, A. M.; Grieshop, A. P.; Lane, T. E.; Pandis, S. N.; Pierce, J. R., 2007. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 315, 1259-1262.

Top-pair production at hadron colliders with next-to-next-to-leading logarithmic soft-gluon resummation

NASA Astrophysics Data System (ADS)

Cacciari, Matteo; Czakon, Michał; Mangano, Michelangelo; Mitov, Alexander; Nason, Paolo

2012-04-01

Incorporating all recent theoretical advances, we resum soft-gluon corrections to the total ttbar cross-section at hadron colliders at the next-to-next-to-leading logarithmic (NNLL) order. We perform the resummation in the well established framework of Mellin N-space resummation. We exhaustively study the sources of systematic uncertainty like renormalization and factorization scale variation, power suppressed effects and missing two- and higher-loop corrections. The inclusion of soft-gluon resummation at NNLL brings only a minor decrease in the perturbative uncertainty with respect to the NLL approximation, and a small shift in the central value, consistent with the quoted uncertainties. These numerical predictions agree with the currently available measurements from the Tevatron and LHC and have uncertainty of similar size. We conclude that significant improvements in the ttbar cross-sections can potentially be expected only upon inclusion of the complete NNLO corrections.

Non-linear regime of the Generalized Minimal Massive Gravity in critical points

NASA Astrophysics Data System (ADS)

Setare, M. R.; Adami, H.

2016-03-01

The Generalized Minimal Massive Gravity (GMMG) theory is realized by adding the CS deformation term, the higher derivative deformation term, and an extra term to pure Einstein gravity with a negative cosmological constant. In the present paper we obtain exact solutions to the GMMG field equations in the non-linear regime of the model. GMMG model about AdS_3 space is conjectured to be dual to a 2-dimensional CFT. We study the theory in critical points corresponding to the central charges c_-=0 or c_+=0, in the non-linear regime. We show that AdS_3 wave solutions are present, and have logarithmic form in critical points. Then we study the AdS_3 non-linear deformation solution. Furthermore we obtain logarithmic deformation of extremal BTZ black hole. After that using Abbott-Deser-Tekin method we calculate the energy and angular momentum of these types of black hole solutions.

Level statistics of a noncompact cosmological billiard

NASA Astrophysics Data System (ADS)

Csordas, Andras; Graham, Robert; Szepfalusy, Peter

1991-08-01

A noncompact chaotic billiard on a two-dimensional space of constant negative curvature, the infinite equilateral triangle describing anisotropy oscillations in the very early universe, is studied quantum-mechanically. A Weyl formula with a logarithmic correction term is derived for the smoothed number of states function. For one symmetry class of the eigenfunctions, the level spacing distribution, the spectral rigidity Delta3, and the Sigma2 statistics are determined numerically using the finite matrix approximation. Systematic deviations are found both from the Gaussian orthogonal ensemble (GOE) and the Poissonian ensemble. However, good agreement with the GOE is found if the fundamental triangle is deformed in such a way that it no longer tiles the space.

Combining states without scale hierarchies with ordered parton showers

DOE PAGES

Fischer, Nadine; Prestel, Stefan

2017-09-12

Here, we present a parameter-free scheme to combine fixed-order multi-jet results with parton-shower evolution. The scheme produces jet cross sections with leading-order accuracy in the complete phase space of multiple emissions, resumming large logarithms when appropriate, while not arbitrarily enforcing ordering on momentum configurations beyond the reach of the parton-shower evolution equation. This then requires the development of a matrix-element correction scheme for complex phase-spaces including ordering conditions as well as a systematic scale-setting procedure for unordered phase-space points. Our algorithm does not require a merging-scale parameter. We implement the new method in the Vincia framework and compare to LHCmore » data.« less

Nonlinear Real-Time Optical Signal Processing.

DTIC Science & Technology

1981-06-30

bandwidth and space-bandwidth products. Real-time homonorphic and loga- rithmic filtering by halftone nonlinear processing has been achieved. A...Page ABSTRACT 1 1. RESEARCH OBJECTIVES AND PROGRESS 3 I-- 1.1 Introduction and Project overview 3 1.2 Halftone Processing 9 1.3 Direct Nonlinear...time homomorphic and logarithmic filtering by halftone nonlinear processing has been achieved. A detailed analysis of degradation due to the finite gamma

123s and ABCs: developmental shifts in logarithmic-to-linear responding reflect fluency with sequence values.

PubMed

Hurst, Michelle; Monahan, K Leigh; Heller, Elizabeth; Cordes, Sara

2014-11-01

When placing numbers along a number line with endpoints 0 and 1000, children generally space numbers logarithmically until around the age of 7, when they shift to a predominantly linear pattern of responding. This developmental shift of responding on the number placement task has been argued to be indicative of a shift in the format of the underlying representation of number (Siegler & Opfer, ). In the current study, we provide evidence from both child and adult participants to suggest that performance on the number placement task may not reflect the structure of the mental number line, but instead is a function of the fluency (i.e. ease) with which the individual can work with the values in the sequence. In Experiment 1, adult participants respond logarithmically when placing numbers on a line with less familiar anchors (1639 to 2897), despite linear responding on control tasks with standard anchors involving a similar range (0 to 1287) and a similar numerical magnitude (2000 to 3000). In Experiment 2, we show a similar developmental shift in childhood from logarithmic to linear responding for a non-numerical sequence with no inherent magnitude (the alphabet). In conclusion, we argue that the developmental trend towards linear behavior on the number line task is a product of successful strategy use and mental fluency with the values of the sequence, resulting from familiarity with endpoints and increased knowledge about general ordering principles of the sequence.A video abstract of this article can be viewed at:http://www.youtube.com/watch?v=zg5Q2LIFk3M. © 2014 John Wiley & Sons Ltd.

Leading logarithmic corrections to the muonium hyperfine splitting and to the hydrogen Lamb shift

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

Karshenboim, S.G.

1994-12-31

Main leading corrections with recoil logarithm log(M/m) and low-energy logarithm log(Za) to the Muonium hyperfine splitting axe discussed. Logarithmic corrections have magnitudes of 0.1 {divided_by} 0.3 kHz. Non-leading higher order corrections axe expected to be not larger than 0.1 kHz. Leading logarithmic correction to the Hydrogen Lamb shift is also obtained.

Variational formulation for Black-Scholes equations in stochastic volatility models

NASA Astrophysics Data System (ADS)

Gyulov, Tihomir B.; Valkov, Radoslav L.

2012-11-01

In this note we prove existence and uniqueness of weak solutions to a boundary value problem arising from stochastic volatility models in financial mathematics. Our settings are variational in weighted Sobolev spaces. Nevertheless, as it will become apparent our variational formulation agrees well with the stochastic part of the problem.

78 FR 70072 - Notice of Intent To Grant Exclusive License

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-22

... NATIONAL AERONAUTICS AND SPACE ADMINISTRATION [Notice 13-132] Notice of Intent To Grant Exclusive License AGENCY: National Aeronautics and Space Administration. ACTION: Notice of intent to grant exclusive... Volatiles From Soil Using Microwave Processes, to Space Resources Extraction Technology, Inc., having its...

Phase pupil functions for focal-depth enhancement derived from a Wigner distribution function.

PubMed

Zalvidea, D; Sicre, E E

1998-06-10

A method for obtaining phase-retardation functions, which give rise to an increase of the image focal depth, is proposed. To this end, the Wigner distribution function corresponding to a specific aperture that has an associated small depth of focus in image space is conveniently sheared in the phase-space domain to generate a new Wigner distribution function. From this new function a more uniform on-axis image irradiance can be accomplished. This approach is illustrated by comparison of the imaging performance of both the derived phase function and a previously reported logarithmic phase distribution.

A volatile organic analyzer for Space Station: Description and evaluation of a gas chromatography/ ion mobility

NASA Technical Reports Server (NTRS)

Limero, Thomas F.; James, John T.

1994-01-01

A Volatile Organic Analyzer (VOA) is being developed as an essential component of the Space Station's Environmental Health System (EHS) air quality monitoring strategy to provide warning to the crew and ground personnel if volatile organic compounds exceed established exposure limits. The short duration of most Shuttle flights and the relative simplicity of the contaminant removal mechanism have lessened the concern about crew exposure to air contaminants on the Shuttle. However, the longer missions associated with the Space Station, the complex air revitalization system and the proposed number of experiments have led to a desire for real-time monitoring of the contaminants in the Space Station atmosphere. Achieving the performance requirements established for the VOA within the Space Station resource (e.g., power, weight) allocations led to a novel approach that joined a gas chromatograph (GC) to an ion mobility spectrometer (IMS). The authors of this paper will discuss the rational for selecting the GC/IMS technology as opposed to the more established gas chromatography/mass spectrometry (GC/MS) for the foundation of the VOA. The data presented from preliminary evaluations will demonstrate the versatile capability of the GC/IMS to analyze the major contaminants expected in the Space Station atmosphere. The favorable GC/IMS characteristics illustrated in this paper included excellent sensitivity, dual-mode operation for selective detection, and mobility drift times to distinguish co-eluting GC peaks. Preliminary studies have shown that the GC/IMS technology can meet surpass the performance requirements of the Space Station VOA.

RESOLVE: An International Mission to Search for Volatiles at the Lunar Poles

NASA Technical Reports Server (NTRS)

Larson, William E.; Quinn, Jacqueline W.; Sanders, Gerald B.; Colaprete, Anthony; Elphic, Richard C.; Picard, Martin

2013-01-01

Numerous studies have shown that the use of space resources to manufacture propellant and consumables can significantly reduce the launch mass of space exploration beyond earth orbit. Even the Moon, which has no atmosphere, is ricb in resources that can theoretically be harvested. A series of lunar missions over the last 20 years has shown an unexpected resource on the Moon. There is evidence that water ice and other volatiles useful for the production of propellants are located at the lunar poles, though most of it is located within permanently shadowed craters where accessing these resources is challenging.

Evaluation of Fungal Metabolic Compounds Released to the Air in a Restricted Environment

NASA Technical Reports Server (NTRS)

Ferebee, Robert N.

1991-01-01

The metabolic action of selected fungi species on common components of the interior of Space Station Freedom (SSF) will be tested. When present, volatile organic chemicals will be collected on porous polymer adsorbent columns. Using thermal desorption, the volatile compounds will be passed onto a gas chromatographic column for analysis. The Space Station Freedom (SSF) modular complex will largely be individually self contained and the established air environment will not be easily adjusted. The development and maintenance of a safe working environment offers a considerable challenge. Present plans for use of SSF acknowledge periods of manned activities and alternate times when the station is unmanned. The obvious necessity for clean and safe air and water during periods of use have been pursued as fundamental systems to SSF success. Somewhat less obvious, although perhaps of no less importance to the success of long term cyclic usage, are those periods of inactivity. It is during these periods when spores from microorganisms may be afforded the best conditions to germinate and in the vegetative form react with the complex synthetic chemical polymers which compose the furnishings and hardware of SSF nodes. Biodegradation could constitute a real hygiene problem, if the organisms form and release volatile organic chemicals. Similar problems have been documented in closed and improperly ventilated buildings and work spaces. Many of the metabolic products of fungi and bacterial growth create a variety of health problems. Analytical chemical techniques will first be used to document the growth of Aspergillus, Penicillium, and Cladosporium fungal species on the potential substrates Nomex and Kevlar. Any volatile organics that are released will be measured using the spectrum of gas adsorption chromatography. The level of microbial contamination that is necessary to produce such volatile compounds and the relative amounts expected to accumulate will be estimated.

IMPROVING THE CALIBRATION OF MODELS TO EVALUATE VAPOR MOVEMENT AT UST SITES BY VERTICAL PROFILING OF CONTAMINANTS IN GROUND WATER

EPA Science Inventory

A risk assessment of the movement of vapors of volatile organic contaminants (VOCs) from ground water through the unsaturated zone and into living spaces usually involves a transport and fate model such as the Johnson and Ettinger model. The concentration of volatile organic con...

Detrended cross-correlations between returns, volatility, trading activity, and volume traded for the stock market companies

NASA Astrophysics Data System (ADS)

Rak, Rafał; Drożdż, Stanisław; Kwapień, Jarosław; Oświȩcimka, Paweł

2015-11-01

We consider a few quantities that characterize trading on a stock market in a fixed time interval: logarithmic returns, volatility, trading activity (i.e., the number of transactions), and volume traded. We search for the power-law cross-correlations among these quantities aggregated over different time units from 1 min to 10 min. Our study is based on empirical data from the American stock market consisting of tick-by-tick recordings of 31 stocks listed in Dow Jones Industrial Average during the years 2008-2011. Since all the considered quantities except the returns show strong daily patterns related to the variable trading activity in different parts of a day, which are the most evident in the autocorrelation function, we remove these patterns by detrending before we proceed further with our study. We apply the multifractal detrended cross-correlation analysis with sign preserving (MFCCA) and show that the strongest power-law cross-correlations exist between trading activity and volume traded, while the weakest ones exist (or even do not exist) between the returns and the remaining quantities. We also show that the strongest cross-correlations are carried by those parts of the signals that are characterized by large and medium variance. Our observation that the most convincing power-law cross-correlations occur between trading activity and volume traded reveals the existence of strong fractal-like coupling between these quantities.

Microwave and hot air drying of garlic puree: drying kinetics and quality characteristics

NASA Astrophysics Data System (ADS)

İlter, Işıl; Akyıl, Saniye; Devseren, Esra; Okut, Dilara; Koç, Mehmet; Kaymak Ertekin, Figen

2018-02-01

In this study, the effect of hot air and microwave drying on drying kinetics and some quality characteristics such as water activity, color, optic index and volatile oil of garlic puree was investigated. Optic index representing browning of the garlic puree increased excessively with an increase in microwave power and hot air drying temperature. However, volatile oil content of the dried samples was decreased by increasing of temperature and microwave power. By increasing drying temperature (50, 60 and 70 °C) and microwave power (180, 360 and 540 W), the drying time decreased from 8.5 h to 4 min. In order to determine the kinetic parameters, the experimental drying data were fitted to various semi-empirical models beside 2nd Fick's diffusion equation. Among them, the Page model gave a better fit for microwave-drying, while Logarithmic model gave a better fit for hot air drying. By increasing the microwave power and hot air drying temperature, the effective moisture diffusivity, De values ranged from 0.76×10-8 to 2.85×10-8 m2/s and from 2.21×10-10 to 3.07×10-10 m2/s, respectively. The activation energy was calculated as 20.90 kJ/mol for hot air drying and 21.96 W/g for microwave drying using an Arrhenius type equation.

A volatile organics concentrator for use in monitoring Space Station water quality

NASA Technical Reports Server (NTRS)

Ehntholt, Daniel J.; Bodek, Itamar; Valentine, James R.; Trabanino, Rudy; Vincze, Johanna E.; Sauer, Richard L.

1990-01-01

The process used to identify, select, and design an approach to the isolation and concentration of volatile organic compounds from a water sample prior to chemical analysis in a microgravity environment is discerned. The trade analysis leading to the recommended volatile organics concentrator (VOC) concept to be tested in a breadboard device is presented. The system covers the areas of gases, volatile separation from water, and water removal/gas chromatograph/mass spectrometer interface. Five options for potential use in the VOC and GC/MS system are identified and ranked, and also nine options are presented for separation of volatiles from the water phase. Seven options for use in the water removal/GC column and MS interface are also identified and included in the overall considerations. A final overall recommendation for breadboard VOC testing is given.

The four-loop six-gluon NMHV ratio function

DOE PAGES

Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.

2016-01-11

We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N=4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q¯ differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result againstmore » multi-Regge predictions at NNLL and N 3LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. As a result, we also provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.« less

The four-loop six-gluon NMHV ratio function

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

Dixon, Lance J.; von Hippel, Matt; McLeod, Andrew J.

2016-01-11

We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N = 4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q - differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We testmore » the result against multi- Regge predictions at NNLL and N 3LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We also study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. Furthermore, we provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.« less

Practicality of Evaluating Soft Errors in Commercial sub-90 nm CMOS for Space Applications

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.; LaBel, Kenneth A.

2010-01-01

The purpose of this presentation is to: Highlight space memory evaluation evolution, Review recent developments regarding low-energy proton direct ionization soft errors, Assess current space memory evaluation challenges, including increase of non-volatile technology choices, and Discuss related testing and evaluation complexities.

Volatile Compound-Mediated Interactions between Barley and Pathogenic Fungi in the Soil

PubMed Central

Fiers, Marie; Lognay, Georges; Fauconnier, Marie-Laure; Jijakli, M. Haïssam

2013-01-01

Plants are able to interact with their environment by emitting volatile organic compounds. We investigated the volatile interactions that take place below ground between barley roots and two pathogenic fungi, Cochliobolus sativus and Fusarium culmorum. The volatile molecules emitted by each fungus, by non-infected barley roots and by barley roots infected with one of the fungi or the two of them were extracted by head-space solid phase micro extraction and analyzed by gas chromatography mass spectrometry. The effect of fungal volatiles on barley growth and the effect of barley root volatiles on fungal growth were assessed by cultivating both organisms in a shared atmosphere without any physical contact. The results show that volatile organic compounds, especially terpenes, are newly emitted during the interaction between fungi and barley roots. The volatile molecules released by non-infected barley roots did not significantly affect fungal growth, whereas the volatile molecules released by pathogenic fungi decreased the length of barley roots by 19 to 21.5% and the surface of aerial parts by 15%. The spectrum of the volatiles released by infected barley roots had no significant effect on F. culmorum growth, but decreased C. sativus growth by 13 to 17%. This paper identifies the volatile organic compounds emitted by two pathogenic fungi and shows that pathogenic fungi can modify volatile emission by infected plants. Our results open promising perspectives concerning the biological control of edaphic diseases. PMID:23818966

A Financial Market Model Incorporating Herd Behaviour.

PubMed

Wray, Christopher M; Bishop, Steven R

2016-01-01

Herd behaviour in financial markets is a recurring phenomenon that exacerbates asset price volatility, and is considered a possible contributor to market fragility. While numerous studies investigate herd behaviour in financial markets, it is often considered without reference to the pricing of financial instruments or other market dynamics. Here, a trader interaction model based upon informational cascades in the presence of information thresholds is used to construct a new model of asset price returns that allows for both quiescent and herd-like regimes. Agent interaction is modelled using a stochastic pulse-coupled network, parametrised by information thresholds and a network coupling probability. Agents may possess either one or two information thresholds that, in each case, determine the number of distinct states an agent may occupy before trading takes place. In the case where agents possess two thresholds (labelled as the finite state-space model, corresponding to agents' accumulating information over a bounded state-space), and where coupling strength is maximal, an asymptotic expression for the cascade-size probability is derived and shown to follow a power law when a critical value of network coupling probability is attained. For a range of model parameters, a mixture of negative binomial distributions is used to approximate the cascade-size distribution. This approximation is subsequently used to express the volatility of model price returns in terms of the model parameter which controls the network coupling probability. In the case where agents possess a single pulse-coupling threshold (labelled as the semi-infinite state-space model corresponding to agents' accumulating information over an unbounded state-space), numerical evidence is presented that demonstrates volatility clustering and long-memory patterns in the volatility of asset returns. Finally, output from the model is compared to both the distribution of historical stock returns and the market price of an equity index option.

Logarithmic conformal field theory: beyond an introduction

NASA Astrophysics Data System (ADS)

Creutzig, Thomas; Ridout, David

2013-12-01

This article aims to review a selection of central topics and examples in logarithmic conformal field theory. It begins with the remarkable observation of Cardy that the horizontal crossing probability of critical percolation may be computed analytically within the formalism of boundary conformal field theory. Cardy’s derivation relies on certain implicit assumptions which are shown to lead inexorably to indecomposable modules and logarithmic singularities in correlators. For this, a short introduction to the fusion algorithm of Nahm, Gaberdiel and Kausch is provided. While the percolation logarithmic conformal field theory is still not completely understood, there are several examples for which the formalism familiar from rational conformal field theory, including bulk partition functions, correlation functions, modular transformations, fusion rules and the Verlinde formula, has been successfully generalized. This is illustrated for three examples: the singlet model \\mathfrak {M} (1,2), related to the triplet model \\mathfrak {W} (1,2), symplectic fermions and the fermionic bc ghost system; the fractional level Wess-Zumino-Witten model based on \\widehat{\\mathfrak {sl}} \\left( 2 \\right) at k=-\\frac{1}{2}, related to the bosonic βγ ghost system; and the Wess-Zumino-Witten model for the Lie supergroup \\mathsf {GL} \\left( 1 {\\mid} 1 \\right), related to \\mathsf {SL} \\left( 2 {\\mid} 1 \\right) at k=-\\frac{1}{2} and 1, the Bershadsky-Polyakov algebra W_3^{(2)} and the Feigin-Semikhatov algebras W_n^{(2)}. These examples have been chosen because they represent the most accessible, and most useful, members of the three best-understood families of logarithmic conformal field theories. The logarithmic minimal models \\mathfrak {W} (q,p), the fractional level Wess-Zumino-Witten models, and the Wess-Zumino-Witten models on Lie supergroups (excluding \\mathsf {OSP} \\left( 1 {\\mid} 2n \\right)). In this review, the emphasis lies on the representation theory of the underlying chiral algebra and the modular data pertaining to the characters of the representations. Each of the archetypal logarithmic conformal field theories is studied here by first determining its irreducible spectrum, which turns out to be continuous, as well as a selection of natural reducible, but indecomposable, modules. This is followed by a detailed description of how to obtain character formulae for each irreducible, a derivation of the action of the modular group on the characters, and an application of the Verlinde formula to compute the Grothendieck fusion rules. In each case, the (genuine) fusion rules are known, so comparisons can be made and favourable conclusions drawn. In addition, each example admits an infinite set of simple currents, hence extended symmetry algebras may be constructed and a series of bulk modular invariants computed. The spectrum of such an extended theory is typically discrete and this is how the triplet model \\mathfrak {W} (1,2) arises, for example. Moreover, simple current technology admits a derivation of the extended algebra fusion rules from those of its continuous parent theory. Finally, each example is concluded by a brief description of the computation of some bulk correlators, a discussion of the structure of the bulk state space, and remarks concerning more advanced developments and generalizations. The final part gives a very short account of the theory of staggered modules, the (simplest class of) representations that are responsible for the logarithmic singularities that distinguish logarithmic theories from their rational cousins. These modules are discussed in a generality suitable to encompass all the examples met in this review and some of the very basic structure theory is proven. Then, the important quantities known as logarithmic couplings are reviewed for Virasoro staggered modules and their role as fundamentally important parameters, akin to the three-point constants of rational conformal field theory, is discussed. An appendix is also provided in order to introduce some of the necessary, but perhaps unfamiliar, language of homological algebra.

Italian and Spanish commercial tomato sauces for pasta dressing: study of sensory and head-space profiles by Flash Profiling and solid-phase microextraction-gas chomatography-mass spectrometry.

PubMed

Bendini, Alessandra; Vallverdú-Queralt, Anna; Valli, Enrico; Palagano, Rosa; Lamuela-Raventos, Rosa Maria; Toschi, Tullia Gallina

2017-08-01

The sensory and head-space profiles of Italian and Spanish commercial tomato sauces were investigated. The Flash Profiling method was used to evaluate sensory characteristics. Samples within each set were ranked according to selected descriptors. One hundred volatile compounds were identified by solid-phase microextraction-gas chomatography-mass spectrometry. For Italian samples, the sensory notes of basil/aromatic herbs, acid and cooked tomato were among those perceived most by the assessors, whereas, in Spanish samples, the sensory attributes of garlic/onion and onion/sweet pepper and, in Italian samples, cooked tomato were among those found most frequently. Data were elaborated using multivariate statistical approaches and interesting correlations were observed among the different sensory attributes and related volatile compounds. Spanish samples were characterized by the highest content of volatiles linked to the thermal treatment of tomatoes and to raw and sautéed garlic and onion, whereas the Italian samples were characterized by terpenic compounds typical of basil and volatile molecules derived from fresh tomato. These results confirm the influence of both formulation and production processes on the aromatic profile (sensory attributes and volatile compounds) of tomato products, which is probably related to the different eating habits and culinary traditions in Italy and Spain. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

LAVA Subsystem Integration and Testing for the RESOLVE Payload of the Resource Prospector Mission: Mass Spectrometers and Gas Chromatography

NASA Technical Reports Server (NTRS)

Coan, Mary R.; Stewart, Elaine M.

2015-01-01

The Regolith and Environment Science & Oxygen and Lunar Volatile Extraction (RESOLVE) payload is part of Resource Prospector (RP) along with a rover and a lander that are expected to launch in 2020. RP will identify volatile elements that may be combined and collected to be used for fuel, air, and water in order to enable deeper space exploration. The Resource Prospector mission is a key part of In-Situ Resource Utilization (ISRU). The demand for this method of utilizing resources at the site of exploration is increasing due to the cost of resupply missions and deep space exploration goals. The RESOLVE payload includes the Lunar Advanced Volatile Analysis (LAVA) subsystem. The main instrument used to identify the volatiles evolved from the lunar regolith is the Gas Chromatograph-Mass Spectrometer (GC-MS). LAVA analyzes the volatiles emitted from the Oxygen and Volatile Extraction Node (OVEN) Subsystem. The objective of OVEN is to obtain, weigh, heat and transfer evolved gases to LAVA through the connection between the two subsystems called the LOVEN line. This paper highlights the work completed during a ten week internship that involved the integration, testing, data analysis, and procedure documentation of two candidate mass spectrometers for the LAVA subsystem in order to aid in determining which model to use for flight. Additionally, the examination of data from the integrated Resource Prospector '15 (RP' 15) field test will be presented in order to characterize the amount of water detected from water doped regolith samples.

NAND FLASH Radiation Tolerant Intelligent Memory Stack (RTIMS FLASH)

NASA Astrophysics Data System (ADS)

Sellier, Charles; Wang, Pierre

2014-08-01

The NAND Flash Radiation Tolerant and Intelligent Memory Stack (RTIMS FLASH) is a User's Friendly, Plug-and- Play and Radiation Protected high density NAND Flash Memory. It provides a very high density, radiation hardened by design and non-volatile memory module suitable for all space applications such as commercial or scientific geo-stationary missions, earth observation, navigation, manned space vehicles and deep space scientific exploration. The Intelligent Memory Module embeds a very high density of non-volatile NAND Flash memory and one Intelligent Flash Memory Controller (FMC). The FMC provides the module with a full protection against the radiation effects such as SEL, SEFI and SEU. It's also granting the module with bad block immunity as well as high level service functions that will benefit to the user's applications.

Volatility Spillover in Chinese Steel Markets

NASA Astrophysics Data System (ADS)

Fang, Wen

2018-03-01

This paper examines volatility spillover in Chinese steel markets by comparing spillover effects before and after steel futures market established and finds some interesting change. Volatility spillover method based on multi-GARCH model are proposed. The results show that there is significant proof for spillover effects from B2B electronic market to spot market, and two-way effects between futures and spot market. Market policy planners and practitioners could make decisions according to the master of spillovers. We also find that B2B e-market and futures market can both provide efficient protection against steel price volatility risk, B2B e-market offer a broad-based platform for trading steel commodities over time and space since e-market role in information flow process is dominant.

[Factors influencing ammonia volatilization in a winter wheat field with plastic film mulched ridges and unmulched furrows].

PubMed

Shangguan, Yu-Xian; Shi, Ri-Peng; Li, Na; Han, Kun; Li, Hui-Ke; Wang, Lin-Quan

2012-06-01

The objective of this experiment was to quantify ammonia volatilization from a winter wheat field with plastic film mulched-ridges and unmulched-furrows (PMRF). The trial was conducted during the 2010-2011 winter wheat growing season at Yangling, Shaanxi Province. Ammonia volatilization from the soil was measured using the closed-chamber method. The results indicated that NH3 emission losses ranged between (1.66 +/- 0.3) and (3.28 +/- 0.51) kg x hm(-2) in the PMRF treatment. In comparison, the NH3 emission loss was (4.68 +/- 0.35) kg x ha(-1) in the conventional tillage treatment (i. e., smooth soil surface). The PMRF treatment reduced NH3 emissions by 29.8 to 63.8% compared with the conventional treatment. The NH3 emission losses were equivalent to 1.9% of the applied N in the conventional practice treatment. In contrast, the losses were equivalent to only 0.3% to 0.8% of the applied N in the PMRF treatment. Ammonia emissions were greatest during the first two weeks after sowing. Emissions before winter accounted for 82% of total NH3 emission in the conventional practice treatment, but only 49% to 61% of the total NH3 emission in the PMRF treatment. The soil NH4+ -N content and the soil moisture content had direct effects on NH3 emission before winter in the conventional treatment. In thePMRF treatment, the soil NH4+ -N content had a direct effect on NH3 emission before winter, whereas soil surface temperature and soil moisture had indirect effects. Ammonia emissions after the greening stage were mainly influenced by the soil NH4+ -N content. Simulation results indicated that logarithmic functions best described cumulative NH3 emission in the PMRF + high N rate treatment and the conventional treatment. A linear function best described cumulative NH3 emission in the PMRF + low N rate treatment and the unfertilized treatment. In conclusion, the PMRF treatment can significantly reduce N losses from winter wheat fields by changing the spatial-temporal dynamics of soil NH3 volatilization.

Theoretical colours and isochrones for some Hubble Space Telescope colour systems

NASA Technical Reports Server (NTRS)

Edvardsson, B.; Bell, R. A.

1989-01-01

Synthetic spectra for effective temperatures of 4000-7250 K, logarithmic surface gravities typical of dwarfs and subgiants, and metallicities from solar values to 0.001 of the solar metallicity were used to derive a grid of synthetic surface brightness magnitudes for 21 of the Hubble Space Telescope Wide Field Camera (WFC) band passes. The absolute magnitudes of these 21 band passes are also obtained for a set of globular cluster isochrones with different helium abundances, metallicities, oxygen abundances, and ages. The usefulness and efficiency of different sets of broad and intermediate bandwidth WFC colors for determining ages and metallicities for globular clusters are evaluated.

The micro-environmental impact of volatile organic compound emissions from large-scale assemblies of people in a confined space

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

Dutta, Tanushree

Large-scale assemblies of people in a confined space can exert significant impacts on the local air chemistry due to human emissions of volatile organics. Variations of air-quality in such small scale can be studied by quantifying fingerprint volatile organic compounds (VOCs) such as acetone, toluene, and isoprene produced during concerts, movie screenings, and sport events (like the Olympics and the World Cup). This review summarizes the extent of VOC accumulation resulting from a large population in a confined area or in a small open area during sporting and other recreational activities. Apart from VOCs emitted directly from human bodies (e.g.,more » perspiration and exhaled breath), those released indirectly from other related sources (e.g., smoking, waste disposal, discharge of food-waste, and use of personal-care products) are also discussed. Although direct and indirect emissions of VOCs from human may constitute <1% of the global atmospheric VOCs budget, unique spatiotemporal variations in VOCs species within a confined space can have unforeseen impacts on the local atmosphere to lead to acute human exposure to harmful pollutants.« less

The Tribological Properties of Several Silahydrocarbons for Use in Space Mechanisms

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Jansen, M. J.; Gschwender, L. J.; Snyder, C. E., Jr.; Sharma, S. K.; Predmore, R. E.; Dube, M. J.

2001-01-01

Silahydrocarbons are members of a relatively new class of liquid lubricants with great potential for use in space mechanisms. They are unimolecular species consisting of silicon, carbon, and hydrogen. They possess unique wear, viscosity, and volatility properties while retaining the ability to solubilize conventional additives. The tribological properties of several members of this class, including tri, tetra- and penta-compounds, are presented. These properties include: viscosity-temperature (ASTM D446), viscosity-pressure coefficient, vapor pressure, volatility, lubricant lifetimes, traction, reciprocating and four ball wear rates and bearing performance. Lubricant lifetimes were determined using a vacuum ball bearing simulator, the spiral orbit tribometer (SOT). Wear was measured using a Cameron Plint reciprocating tribometer and wear rates with a vacuum four ball tribometer. Conventional viscometry was used for viscosity-temperature measurements and a Knudsen cell for vapor pressure. Vacuum Thermogravimetric Analysis (TGA) was also used for volatility measurements. Pressure viscosity coefficients (a values) were estimated from EHL (elastohydrodynamic lubrication) film thickness measurements. Traction coefficients were measured with a twin disk traction rig. Bearing tests were performed in a vacuum bearing test facility. These properties are compared to existing state-of-the-art space lubricants.

Space-weathering processes and products on volatile-rich asteroids

NASA Astrophysics Data System (ADS)

Britt, D.; Schelling, P.; Consolmagno, G.; Bradley, T.

2014-07-01

Space weathering is a generic term for the effects on atmosphereless solid bodies in the solar system from a range of processes associated with direct exposure to the space environment. These include impact processes (shock, vaporization, fragmentation, heating, melting, and ejecta formation), radiation damage (from galactic and solar cosmic rays), solar-wind effects (irradiation, ion implantation, and sputtering), and the chemical reactions driven by these processes. The classic example of space weathering is the formation of the lunar spectral red slope associated with the production of nanophase Fe (npFe0) in the dusty lunar regolith (C.R. Chapman, 2004, Annual Review of Earth & Planet. Sci. 32, C.M. Pieters, 2000, MAPS 35). Similar npFe0 has been recovered from asteroid (25143) Itokawa and some asteroid classes do exhibit modest spectral red slopes (T. Noguchi, 2011, Science 333). Space weathering can be thought of as driven by a combination of the chemical environment of space (hard vacuum, low oxygen fugacity, solar-wind implantation of hydrogen) along with thermal energy supplied by micrometeorite impacts. The forward modeling of space weathering as thermodynamically-driven decomposition of common rock-forming minerals suggests the production of a range of daughter products: (1) The silicate products typically lose oxygen, other volatile elements (i.e., sulfur and sodium), and metallic cations, producing minerals that are typically more disordered and less optically active than the original parent materials. (2) The decomposed metallic cations form in nano-sized blebs including npFe0, on the surfaces or in condensing rims of mineral grains. This creates a powerful optical component as seen in the lunar red slope. Surfaces with exposed npFe0 are an ideal environment for catalyzing further reactions. (3) The liberated volatile elements and gases (O, S, Na) may form an observable exosphere (e.g., Moon and Mercury) and can either escape from the body or recombine with available solar-wind-implanted hydrogen to form trace amounts of water and OH. Mineral decomposition can be thought of as the first stage of space weathering. It produces weathered surfaces somewhat depleted in volatile elements, creates a predictable set of minor or trace minerals, and leaves the surfaces with catalytic species, primarily npFe0. However, a second stage of further reactions and weathering depends upon the presence of ''feed-stock'' components that can participate in catalyzed chemical reactions on exposed surfaces. For volatile-rich small bodies, the available materials are not only silicates, but a volatile feedstock that can include water, carbon monoxide, ammonia, to name a few. Thermodynamically-driven decomposition of silicates will produce trace amounts of npFe0 which are ideal sites for Fischer-Tropsch type (FTT) catalytic reactions that can produce organics in situ on the asteroids including alkanes, polyaromatic hydrocarbons, and amino acids (J.E. Elsila, 2012, MAPS 47). The mix and range of products depends on the composition and morphology of the mineral surface, energy inputs produced by the micrometeorite impacts or other processes, and the composition of the input volatile feedstock. FFT reactions generate long-chain carbon compounds and amino acids. Secondary reactions that generate more complex carbon compounds and amino acids are likely to occur as the organic material matures. Weathering maturity can be thought of as a function of the abundance and diversity of the weathering products. Since the npFe0 is not destroyed in the reaction, continued micrometeorite bombardment would result in continuing processing and recombination of the existing organic feedstock. More weathering would result in progressively longer-chain carbon compounds as well as more complex and diverse amino acids, and eventually the kerogen-like insoluble-organic matter that forms a large fraction of carbonaceous meteorites. This insight has several major implications for our planetary science and, potentially, the formation of the precursors of life. First, the range of weathering products seen in remotely-sensed data, meteorites, and returned samples are not random, but the predictable outcome of the source region's mineral kinetics and chemical feedstock. Weathering products do not have to be optically active like the npFe0 that produces the lunar red slope; on the contrary, probably most weathering products are spectrally neutral or even suppress an object's near-IR reflectance spectrum. In the case of volatile-rich parent bodies, a major weathering product is a range of carbon-rich compounds. But an additional result of considerable interest is the generation of pre-biotic compounds as a routine and predictable byproduct of common space-weathering processes. Any atmosphereless body around any star with mafic silicate mineral compositions and volatile feedstocks should create amino acids as a standard byproduct of space weathering. The precursors of life are probably abundant in any space-weathered asteroid belt, in any solar system, and only wait being accreted to a hospitable environment.

Challenges of Rover Navigation at the Lunar Poles

NASA Technical Reports Server (NTRS)

Nefian, Ara; Deans, Matt; Bouyssounouse, Xavier; Edwards, Larry; Dille, Michael; Fong, Terry; Colaprete, Tony; Miller, Scott; Vaughan, Ryan; Andrews, Dan;

Kinetics of diffusion-controlled annihilation with sparse initial conditions

DOE PAGES

Ben-Naim, Eli; Krapivsky, Paul

2016-12-16

Here, we study diffusion-controlled single-species annihilation with sparse initial conditions. In this random process, particles undergo Brownian motion, and when two particles meet, both disappear. We also focus on sparse initial conditions where particles occupy a subspace of dimension δ that is embedded in a larger space of dimension d. Furthermore, we find that the co-dimension Δ = d - δ governs the behavior. All particles disappear when the co-dimension is sufficiently small, Δ ≤ 2; otherwise, a finite fraction of particles indefinitely survive. We establish the asymptotic behavior of the probability S(t) that a test particle survives until time t. When the subspace is a line, δ = 1, we find inverse logarithmic decay,more » $$S\\sim {(\\mathrm{ln}t)}^{-1}$$, in three dimensions, and a modified power-law decay, $$S\\sim (\\mathrm{ln}t){t}^{-1/2}$$, in two dimensions. In general, the survival probability decays algebraically when Δ < 2, and there is an inverse logarithmic decay at the critical co-dimension Δ = 2.« less

Compression technique for large statistical data bases

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

Eggers, S.J.; Olken, F.; Shoshani, A.

1981-03-01

The compression of large statistical databases is explored and are proposed for organizing the compressed data, such that the time required to access the data is logarithmic. The techniques exploit special characteristics of statistical databases, namely, variation in the space required for the natural encoding of integer attributes, a prevalence of a few repeating values or constants, and the clustering of both data of the same length and constants in long, separate series. The techniques are variations of run-length encoding, in which modified run-lengths for the series are extracted from the data stream and stored in a header, which ismore » used to form the base level of a B-tree index into the database. The run-lengths are cumulative, and therefore the access time of the data is logarithmic in the size of the header. The details of the compression scheme and its implementation are discussed, several special cases are presented, and an analysis is given of the relative performance of the various versions.« less

A quick response four decade logarithmic high-voltage stepping supply

NASA Technical Reports Server (NTRS)

Doong, H.

1978-01-01

An improved high-voltage stepping supply, for space instrumentation is described where low power consumption and fast settling time between steps are required. The high-voltage stepping supply, utilizing an average power of 750 milliwatts, delivers a pair of mirror images with 64 level logarithmic outputs. It covers a four decade range of + or - 2500 to + or - 0.29 volts having an output stability of + or - 0.5 percent or + or - 20 millivolts for all line load and temperature variations. The supply provides a typical step setting time of 1 millisecond with 100 microseconds for the lower two decades. The versatile design features of the high-voltage stepping supply provides a quick response staircase generator as described or a fixed voltage with the option to change levels as required over large dynamic ranges without circuit modifications. The concept can be implemented up to + or - 5000 volts. With these design features, the high-voltage stepping supply should find numerous applications where charged particle detection, electro-optical systems, and high voltage scientific instruments are used.

Self-induced conversion in dense neutrino gases: Pendulum in flavor space

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

Hannestad, Steen; Max-Planck-Institut fuer Physik; Raffelt, Georg G.

Neutrino-neutrino interactions can lead to collective flavor conversion effects in supernovae and in the early universe. We demonstrate that the case of bipolar oscillations, where a dense gas of neutrinos and antineutrinos in equal numbers completely converts from one flavor to another even if the mixing angle is small, is equivalent to a pendulum in flavor space. Bipolar flavor conversion corresponds to the swinging of the pendulum, which begins in an unstable upright position (the initial flavor), and passes through momentarily the vertically downward position (the other flavor) in the course of its motion. The time scale to complete onemore » cycle of oscillation depends logarithmically on the vacuum mixing angle. Likewise, the presence of an ordinary medium can be shown analytically to contribute to a logarithmic increase in the bipolar conversion period. We further find that a more complex (and realistic) system of unequal numbers of neutrinos and antineutrinos is analogous to a spinning top subject to a torque. This analogy easily explains how such a system can oscillate in both the bipolar and the synchronized mode, depending on the neutrino density and the size of the neutrino-antineutrino asymmetry. Our simple model applies strictly only to isotropic neutrino gasses. In more general cases, and especially for neutrinos streaming from a supernova core, different modes couple to each other with unequal strength, an effect that can lead to kinematical decoherence in flavor space rather than collective oscillations. The exact circumstances under which collective oscillations occur in nonisotropic media remain to be understood.« less

MAVEN Atlas V Launch

NASA Image and Video Library

2013-11-18

The United Launch Alliance Atlas V rocket with NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft launches from the Cape Canaveral Air Force Station Space Launch Complex 41, Monday, Nov. 18, 2013, Cape Canaveral, Florida. NASA’s Mars-bound spacecraft, the Mars Atmosphere and Volatile EvolutioN, or MAVEN, is the first spacecraft devoted to exploring and understanding the Martian upper atmosphere. Photo Credit: (NASA/Bill Ingalls)

Rapid differentiation of Chinese hop varieties (Humulus lupulus) using volatile fingerprinting by HS-SPME-GC-MS combined with multivariate statistical analysis.

PubMed

Liu, Zechang; Wang, Liping; Liu, Yumei

2018-01-18

Hops impart flavor to beer, with the volatile components characterizing the various hop varieties and qualities. Fingerprinting, especially flavor fingerprinting, is often used to identify 'flavor products' because inconsistencies in the description of flavor may lead to an incorrect definition of beer quality. Compared to flavor fingerprinting, volatile fingerprinting is simpler and easier. We performed volatile fingerprinting using head space-solid phase micro-extraction gas chromatography-mass spectrometry combined with similarity analysis and principal component analysis (PCA) for evaluating and distinguishing between three major Chinese hops. Eighty-four volatiles were identified, which were classified into seven categories. Volatile fingerprinting based on similarity analysis did not yield any obvious result. By contrast, hop varieties and qualities were identified using volatile fingerprinting based on PCA. The potential variables explained the variance in the three hop varieties. In addition, the dendrogram and principal component score plot described the differences and classifications of hops. Volatile fingerprinting plus multivariate statistical analysis can rapidly differentiate between the different varieties and qualities of the three major Chinese hops. Furthermore, this method can be used as a reference in other fields. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

QLog Solar-Cell Mode Photodiode Logarithmic CMOS Pixel Using Charge Compression and Readout †

PubMed Central

Ni, Yang

2018-01-01

In this paper, we present a new logarithmic pixel design currently under development at New Imaging Technologies SA (NIT). This new logarithmic pixel design uses charge domain logarithmic signal compression and charge-transfer-based signal readout. This structure gives a linear response in low light conditions and logarithmic response in high light conditions. The charge transfer readout efficiently suppresses the reset (KTC) noise by using true correlated double sampling (CDS) in low light conditions. In high light conditions, thanks to charge domain logarithmic compression, it has been demonstrated that 3000 electrons should be enough to cover a 120 dB dynamic range with a mobile phone camera-like signal-to-noise ratio (SNR) over the whole dynamic range. This low electron count permits the use of ultra-small floating diffusion capacitance (sub-fF) without charge overflow. The resulting large conversion gain permits a single photon detection capability with a wide dynamic range without a complex sensor/system design. A first prototype sensor with 320 × 240 pixels has been implemented to validate this charge domain logarithmic pixel concept and modeling. The first experimental results validate the logarithmic charge compression theory and the low readout noise due to the charge-transfer-based readout. PMID:29443903

QLog Solar-Cell Mode Photodiode Logarithmic CMOS Pixel Using Charge Compression and Readout.

PubMed

Ni, Yang

2018-02-14

In this paper, we present a new logarithmic pixel design currently under development at New Imaging Technologies SA (NIT). This new logarithmic pixel design uses charge domain logarithmic signal compression and charge-transfer-based signal readout. This structure gives a linear response in low light conditions and logarithmic response in high light conditions. The charge transfer readout efficiently suppresses the reset (KTC) noise by using true correlated double sampling (CDS) in low light conditions. In high light conditions, thanks to charge domain logarithmic compression, it has been demonstrated that 3000 electrons should be enough to cover a 120 dB dynamic range with a mobile phone camera-like signal-to-noise ratio (SNR) over the whole dynamic range. This low electron count permits the use of ultra-small floating diffusion capacitance (sub-fF) without charge overflow. The resulting large conversion gain permits a single photon detection capability with a wide dynamic range without a complex sensor/system design. A first prototype sensor with 320 × 240 pixels has been implemented to validate this charge domain logarithmic pixel concept and modeling. The first experimental results validate the logarithmic charge compression theory and the low readout noise due to the charge-transfer-based readout.

Martian stable isotopes: volatile evolution, climate change and exobiological implications

NASA Technical Reports Server (NTRS)

Jakosky, B. M.

1999-01-01

Measurements of the ratios of stable isotopes in the martian atmosphere and crust provide fundamental information about the evolution of the martian volatile and climate system. Current best estimates of the isotope ratios indicate that there has been substantial loss of gases to space and exchange of gases between the atmosphere and the crust throughout geologic time; exchange may have occurred through circulation of water in hydrothermal systems. Processes of volatile evolution and exchange will fractionate the isotopes in a manner that complicates the possible interpretation of isotopic data in terms of any fractionation that may have been caused by martian biota, and must be understood first. Key measurements are suggested that will enhance our understanding of the non-biological fractionation of the isotopes and of the evolution of the martian volatile system.

Investigation of logarithmic spiral nanoantennas at optical frequencies

NASA Astrophysics Data System (ADS)

Verma, Anamika; Pandey, Awanish; Mishra, Vigyanshu; Singh, Ten; Alam, Aftab; Dinesh Kumar, V.

2013-12-01

The first study is reported of a logarithmic spiral antenna in the optical frequency range. Using the finite integration technique, we investigated the spectral and radiation properties of a logarithmic spiral nanoantenna and a complementary structure made of thin gold film. A comparison is made with results for an Archimedean spiral nanoantenna. Such nanoantennas can exhibit broadband behavior that is independent of polarization. Two prominent features of logarithmic spiral nanoantennas are highly directional far field emission and perfectly circularly polarized radiation when excited by a linearly polarized source. The logarithmic spiral nanoantenna promises potential advantages over Archimedean spirals and could be harnessed for several applications in nanophotonics and allied areas.

Multifractality and freezing phenomena in random energy landscapes: An introduction

NASA Astrophysics Data System (ADS)

Fyodorov, Yan V.

2010-10-01

We start our lectures with introducing and discussing the general notion of multifractality spectrum for random measures on lattices, and how it can be probed using moments of that measure. Then we show that the Boltzmann-Gibbs probability distributions generated by logarithmically correlated random potentials provide a simple yet non-trivial example of disorder-induced multifractal measures. The typical values of the multifractality exponents can be extracted from calculating the free energy of the associated Statistical Mechanics problem. To succeed in such a calculation we introduce and discuss in some detail two analytically tractable models for logarithmically correlated potentials. The first model uses a special definition of distances between points in space and is based on the idea of multiplicative cascades which originated in theory of turbulent motion. It is essentially equivalent to statistical mechanics of directed polymers on disordered trees studied long ago by Derrida and Spohn (1988) in Ref. [12]. In this way we introduce the notion of the freezing transition which is identified with an abrupt change in the multifractality spectrum. Second model which allows for explicit analytical evaluation of the free energy is the infinite-dimensional version of the problem which can be solved by employing the replica trick. In particular, the latter version allows one to identify the freezing phenomenon with a mechanism of the replica symmetry breaking (RSB) and to elucidate its physical meaning. The corresponding one-step RSB solution turns out to be marginally stable everywhere in the low-temperature phase. We finish with a short discussion of recent developments and extensions of models with logarithmic correlations, in particular in the context of extreme value statistics. The first appendix summarizes the standard elementary information about Gaussian integrals and related subjects, and introduces the notion of the Gaussian free field characterized by logarithmic correlations. Three other appendices provide the detailed exposition of a few technical details underlying the replica analysis of the model discussed in the lectures.

One-Loop Test of Quantum Black Holes in anti–de Sitter Space

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

Liu, James T.; Pando Zayas, Leopoldo A.; Rathee, Vimal

Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS4 black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.

Electronic filters, signal conversion apparatus, hearing aids and methods

NASA Technical Reports Server (NTRS)

Morley, Jr., Robert E. (Inventor); Engebretson, A. Maynard (Inventor); Engel, George L. (Inventor); Sullivan, Thomas J. (Inventor)

1992-01-01

An electronic filter for filtering an electrical signal. Signal processing circuitry therein includes a logarithmic filter having a series of filter stages with inputs and outputs in cascade and respective circuits as GOVERNMENT SUPPORT This invention was made with U.S. Government support under Veterans Administration Contract VA KV 674P857 and National Aeronautics and Space Administration (NASA) Research Grant No. NAG10-0040. The U.S. Government has certain rights in this invention.

One-Loop Test of Quantum Black Holes in anti–de Sitter Space

DOE PAGES

Liu, James T.; Pando Zayas, Leopoldo A.; Rathee, Vimal; ...

2018-06-01

Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS4 black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.

One-Loop Test of Quantum Black Holes in anti-de Sitter Space

NASA Astrophysics Data System (ADS)

Liu, James T.; Pando Zayas, Leopoldo A.; Rathee, Vimal; Zhao, Wenli

2018-06-01

Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS4 black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.

One-Loop Test of Quantum Black Holes in anti-de Sitter Space.

PubMed

Liu, James T; Pando Zayas, Leopoldo A; Rathee, Vimal; Zhao, Wenli

2018-06-01

Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS_{4} black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.

A scale-entropy diffusion equation to describe the multi-scale features of turbulent flames near a wall

NASA Astrophysics Data System (ADS)

Queiros-Conde, D.; Foucher, F.; Mounaïm-Rousselle, C.; Kassem, H.; Feidt, M.

2008-12-01

Multi-scale features of turbulent flames near a wall display two kinds of scale-dependent fractal features. In scale-space, an unique fractal dimension cannot be defined and the fractal dimension of the front is scale-dependent. Moreover, when the front approaches the wall, this dependency changes: fractal dimension also depends on the wall-distance. Our aim here is to propose a general geometrical framework that provides the possibility to integrate these two cases, in order to describe the multi-scale structure of turbulent flames interacting with a wall. Based on the scale-entropy quantity, which is simply linked to the roughness of the front, we thus introduce a general scale-entropy diffusion equation. We define the notion of “scale-evolutivity” which characterises the deviation of a multi-scale system from the pure fractal behaviour. The specific case of a constant “scale-evolutivity” over the scale-range is studied. In this case, called “parabolic scaling”, the fractal dimension is a linear function of the logarithm of scale. The case of a constant scale-evolutivity in the wall-distance space implies that the fractal dimension depends linearly on the logarithm of the wall-distance. We then verified experimentally, that parabolic scaling represents a good approximation of the real multi-scale features of turbulent flames near a wall.

Next-to-leading-logarithmic power corrections for N -jettiness subtraction in color-singlet production

NASA Astrophysics Data System (ADS)

Boughezal, Radja; Isgrò, Andrea; Petriello, Frank

2018-04-01

We present a detailed derivation of the power corrections to the factorization theorem for the 0-jettiness event shape variable T . Our calculation is performed directly in QCD without using the formalism of effective field theory. We analytically calculate the next-to-leading logarithmic power corrections for small T at next-to-leading order in the strong coupling constant, extending previous computations which obtained only the leading-logarithmic power corrections. We address a discrepancy in the literature between results for the leading-logarithmic power corrections to a particular definition of 0-jettiness. We present a numerical study of the power corrections in the context of their application to the N -jettiness subtraction method for higher-order calculations, using gluon-fusion Higgs production as an example. The inclusion of the next-to-leading-logarithmic power corrections further improves the numerical efficiency of the approach beyond the improvement obtained from the leading-logarithmic power corrections.

Lunar Ice Cube: Development of a Deep Space Cubesat Mission

NASA Astrophysics Data System (ADS)

Clark, P. E.; Malphrus, B.; McElroy, D.; Schabert, J.; Wilczewski, S.; Farrell, W.; Brambora, C.; Macdowall, R.; Folta, D.; Hurford, T.; Patel, D.; Banks, S.; Reuter, D.; Brown, K.; Angkasa, K.; Tsay, M.

2017-10-01

Lunar Ice Cube, a 6U deep space cubesat mission, will be deployed by EM1. It will demonstrate cubesat propulsion, the Busek BIT 3 RF Ion engine, and a compact instrument capable of addressing HEOMD Strategic Knowledge Gaps related to lunar volatiles.

KSC-2013-3980

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, from the left, Lisa May, MAVEN Program executive, Kelly Fast, Mars Program scientist, Sandra Cauffman, deputy project manager at the agency's Goddard Spaceflight Center, in Greenbelt, Md., and Chris Waters, systems design team lead at Lockheed Martin. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3981

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, from the left, Lisa May, MAVEN Program executive, Kelly Fast, Mars Program scientist, Sandra Cauffman, deputy project manager at the agency's Goddard Spaceflight Center, in Greenbelt, Md., and Chris Waters, systems design team lead at Lockheed Martin. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3982

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the Mars Atmosphere and Volatile Evolution, or MAVEN, mission by, from the left, Lisa May, MAVEN Program executive, Kelly Fast, Mars Program scientist, Sandra Cauffman, deputy project manager at the agency's Goddard Spaceflight Center, in Greenbelt, Md., and Chris Waters, systems design team lead at Lockheed Martin. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

Effect of milk on the deodorization of malodorous breath after garlic ingestion.

PubMed

Hansanugrum, Areerat; Barringer, Sheryl A

2010-08-01

The effect of milk and milk components on the deodorization of diallyl disulfide (DADS), allyl methyl disulfide (AMDS), allyl mercaptan (AM), allyl methyl sulfide (AMS), and methyl mercaptan (MM) in the headspace of garlic as well as in the mouth- and nose-space after garlic ingestion was investigated using selected ion flow tube-mass spectrometry (SIFT-MS). Fat-free and whole milk significantly reduced the head-, mouth-, and nose-space concentrations of all volatiles. Water was the major component in milk responsible for the deodorization of volatiles. Due to its higher fat content, whole milk was more effective than fat-free milk in the deodorization of the more hydrophobic volatiles diallyl disulfide and allyl methyl disulfide. Milk was more effective than water and 10% sodium caseinate in the deodorization of allyl methyl sulfide, a persistent garlic odor, in the mouth after garlic ingestion. Addition of milk to garlic before ingestion had a higher deodorizing effect on the volatiles in the mouth than drinking milk after consuming garlic. Practical Application: Ingesting beverages or foods with high water and/or fat content such as milk may help reduce the malodorous odor in breath after garlic ingestion and mask the garlic flavor during eating. To enhance the deodorizing effect, deodorant foods should be mixed with garlic before ingestion.

Thin film heater for removable volatile protecting coatings.

PubMed

Karim, Abid

2013-01-01

Freshly coated aluminum mirrors have excellent reflectivity at far ultraviolet wavelengths. However, reflectivity rapidly degrades when the mirror surfaces are exposed to atmosphere. In order to avoid this problem, freshly coated aluminum surface can be protected by over-coating of a removable volatile protecting coating. This protecting coating can be re-evaporated by controlled heating or by some other methods when required. This type of removable coating has immediate application in UV space astronomy. The purpose of this paper is to demonstrate the feasibility of re-evaporation of removable volatile Zn protecting coating using a NiCr thin film heater without affecting the reflection properties of Al mirror surfaces.

Modeling the Stability of Volatile Deposits in Lunar Cold Traps

NASA Technical Reports Server (NTRS)

Crider, D. H.; Vondrak, R. R.

2002-01-01

There are several mechanisms acting at the cold traps that can alter the inventory of volatiles there. Primarily, the lunar surface is bombarded by meteoroids which impact, melt, process, and redistribute the regolith. Further, solar wind and magnetospheric ion fluxes are allowed limited access onto the regions in permanent shadow. Also, although cold traps are in the permanent shadow of the Sun, there is a small flux of radiation incident on the regions from interstellar sources. We investigate the effects of these space weathering processes on a deposit of volatiles in a lunar cold trap through simulations. We simulate the development of a column of material near the surface of the Moon resulting from space weathering. This simulation treats a column of material at a lunar cold trap and focuses on the hydrogen content of the column. We model space weathering processes on several time and spatial scales to simulate the constant rain of micrometeoroids as well as sporadic larger impactors occurring near the cold traps to determine the retention efficiency of the cold traps. We perform the Monte Carlo simulation over many columns of material to determine the expectation value for hydrogen content of the top few meters of soil for comparison with Lunar Prospector neutron data.

Extraction of volatiles and metals from extraterrestrial materials

NASA Technical Reports Server (NTRS)

Lewis, J. S.

1992-01-01

Recent progress in defining the physical, orbital, and chemical properties of the Earth-crossing asteroid and comet population was integrated into an elaborate Monte Carlo model of the fluxes of bodies in the inner Solar System. This model is of use in projecting flight opportunities to as-yet undiscovered near-Earth objects and in assessing the impact hazard to life on Earth and the evolutionary consequences of impacts on the other terrestrial planets. Further progress was made in defining desirable transportation system architectures for the use of non-terrestrial volatiles and metals, including the delivery of propellants to near-Earth space for fueling of space exploration initiative (SEI) type expeditions, the construction and resupply of Solar Power Satellite constellations in various Earth orbits (including geosynchronous earth orbit (GEO) and Highly Eccentric Earth Orbit (HEEO)), and retrieval of He-3 for use as a clean fusion fuel on Earth. These studies suggest a greater future role for SERC in the exploration of space energy sources to meet Earth's 21st-century energy requirements. Laboratory studies of volatilization and deposition of ferrous metal alloys demonstrated deposition of strong iron films from carbonyl chemical vapor deposition (CVD), showing the crucial role of additive gases in governing the CVD process, and pointing the way to specific experiments on extraction and deposition of ferrous metals from nonterrestrial materials.

Prospecting for Polar Volatiles: Results from the Resolve Field

NASA Technical Reports Server (NTRS)

Elphic, Richard C.; Colarprete, Anthony; Deans, Matthew C.; Heldman, Jennifer; Sanders, Gerald B.; Larson, William E.

2013-01-01

Both the Moon and Mercury evidently host ice and other volatile compounds in cold traps at the planets poles. Determining the form, spatial distribution, and abundance of these volatiles at the lunar poles can help us understand how and when they were delivered and emplaced. This bears directly on the delivery of water and prebiotic compounds to the inner planets over the solar system s history, and also informs plans for utilizing the volatiles as resources for sustained human exploration as well as the commercial development of space. Temperature models and orbital data suggest near-surface volatile concentrations may exist at polar locations not strictly in permanent shadow. Remote operation of a robotic lunar rover mission for the 7-10 days of available sunlight would permit key questions to be answered. But such a short, quick-tempo mission has unique challenges and requires a new concept of operations. Both science and rover operations decisionmaking must be done in real time, requiring immediate situational awareness, data analysis, and decision support tools.

NASA's 3D Flight Computer for Space Applications

NASA Technical Reports Server (NTRS)

Alkalai, Leon

2000-01-01

The New Millennium Program (NMP) Integrated Product Development Team (IPDT) for Microelectronics Systems was planning to validate a newly developed 3D Flight Computer system on its first deep-space flight, DS1, launched in October 1998. This computer, developed in the 1995-97 time frame, contains many new computer technologies previously never used in deep-space systems. They include: advanced 3D packaging architecture for future low-mass and low-volume avionics systems; high-density 3D packaged chip-stacks for both volatile and non-volatile mass memory: 400 Mbytes of local DRAM memory, and 128 Mbytes of Flash memory; high-bandwidth Peripheral Component Interface (Per) local-bus with a bridge to VME; high-bandwidth (20 Mbps) fiber-optic serial bus; and other attributes, such as standard support for Design for Testability (DFT). Even though this computer system did not complete on time for delivery to the DS1 project, it was an important development along a technology roadmap towards highly integrated and highly miniaturized avionics systems for deep-space applications. This continued technology development is now being performed by NASA's Deep Space System Development Program (also known as X2000) and within JPL's Center for Integrated Space Microsystems (CISM).

A rapid space-resolved solid-phase microextraction method as a powerful tool to determine contaminants in wine based on their volatility.

PubMed

Liu, Min; Peng, Qing-Qing; Chen, Yu-Feng; Tang, Qian; Feng, Qing

2015-06-01

A novel space-resolved solid phase microextraction (SR-SPME) technique was developed to facilitate simultaneously analyte monitoring within heterogeneous samples. Graphene (G) and graphene oxide (GO) were coated separately to the segmented fibers which were successfully used for the solid-phase microextraction of two contaminants with dramatically different volatility: 2,4,6-trichloroanisole (TCA) and dibutyl phthalate (DBP). The space-resolved fiber showed good precision (5.4%, 6.8%), low detection limits (0.3ng/L, 0.3ng/L), and wide linearity (1.0-250.0ng/L, 1.0-250.0ng/L) under the optimized conditions for TCA and DBP, respectively. The method was applied to simultaneous analysis of the two contaminates with satisfactory recoveries, which were 96.96% and 98.20% for wine samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Crystal growth of device quality GaAs in space

NASA Technical Reports Server (NTRS)

Gatos, H. C.; Lagowski, J.

1986-01-01

It was established that the findings on elemental semiconductors Ge and Si regarding crystal growth, segregation, chemical composition, defect interactions, and materials properties-electronic properties relationships are not necessarily applicable to GaAs (and to other semiconductor compounds). In many instances totally unexpected relationships were found to prevail. It was further established that in compound semiconductors with a volatile constituent, control of stoichiometry is far more critical than any other crystal growth parameter. It was also shown that, due to suppression of nonstoichiometric fluctuations, the advantages of space for growth of semiconductor compounds extend far beyond those observed in elemental semiconductors. A novel configuration was discovered for partial confinement of GaAs melt in space which overcomes the two major problems associated with growth of semiconductors in total confinement. They are volume expansion during solidification and control of pressure of the volatile constituent. These problems are discussed in detail.

Structural characterization of graphene layers in various Indian coals by X-Ray Diffraction technique

NASA Astrophysics Data System (ADS)

Manoj, B.; Kunjomana, A. G.

2015-02-01

The results of the structural investigation of three Indian coals showed that, the structural parameters like fa & Lc increased where as interlayer spacing d002 decreased with increase in carbon content, aromaticity and coal rank. These structural parameters change just opposite with increase in volatile matter content. Considering the 'turbostratic' structure for coals, the minimum separation between aromatic lamellae was found to vary between 3.34 to 3.61 A° for these coals. As the aromaticity increased, the interlayer spacing decreased an indication of more graphitization of the sample. Volatile matter and carbon content had a strong influence on the aromaticity, interlayer spacing and stacking height on the sample. The average number of carbon atoms per aromatic lamellae and number of layers in the lamellae was found to be 16-21 and 7-8 for all the samples.

High-frequency stock linkage and multi-dimensional stationary processes

NASA Astrophysics Data System (ADS)

Wang, Xi; Bao, Si; Chen, Jingchao

2017-02-01

In recent years, China's stock market has experienced dramatic fluctuations; in particular, in the second half of 2014 and 2015, the market rose sharply and fell quickly. Many classical financial phenomena, such as stock plate linkage, appeared repeatedly during this period. In general, these phenomena have usually been studied using daily-level data or minute-level data. Our paper focuses on the linkage phenomenon in Chinese stock 5-second-level data during this extremely volatile period. The method used to select the linkage points and the arbitrage strategy are both based on multi-dimensional stationary processes. A new program method for testing the multi-dimensional stationary process is proposed in our paper, and the detailed program is presented in the paper's appendix. Because of the existence of the stationary process, the strategy's logarithmic cumulative average return will converge under the condition of the strong ergodic theorem, and this ensures the effectiveness of the stocks' linkage points and the more stable statistical arbitrage strategy.

Nonlinear stochastic interacting dynamics and complexity of financial gasket fractal-like lattice percolation

NASA Astrophysics Data System (ADS)

Zhang, Wei; Wang, Jun

2018-05-01

A novel nonlinear stochastic interacting price dynamics is proposed and investigated by the bond percolation on Sierpinski gasket fractal-like lattice, aim to make a new approach to reproduce and study the complexity dynamics of real security markets. Fractal-like lattices correspond to finite graphs with vertices and edges, which are similar to fractals, and Sierpinski gasket is a well-known example of fractals. Fractional ordinal array entropy and fractional ordinal array complexity are introduced to analyze the complexity behaviors of financial signals. To deeper comprehend the fluctuation characteristics of the stochastic price evolution, the complexity analysis of random logarithmic returns and volatility are preformed, including power-law distribution, fractional sample entropy and fractional ordinal array complexity. For further verifying the rationality and validity of the developed stochastic price evolution, the actual security market dataset are also studied with the same statistical methods for comparison. The empirical results show that this stochastic price dynamics can reconstruct complexity behaviors of the actual security markets to some extent.

A Financial Market Model Incorporating Herd Behaviour

PubMed Central

2016-01-01

Herd behaviour in financial markets is a recurring phenomenon that exacerbates asset price volatility, and is considered a possible contributor to market fragility. While numerous studies investigate herd behaviour in financial markets, it is often considered without reference to the pricing of financial instruments or other market dynamics. Here, a trader interaction model based upon informational cascades in the presence of information thresholds is used to construct a new model of asset price returns that allows for both quiescent and herd-like regimes. Agent interaction is modelled using a stochastic pulse-coupled network, parametrised by information thresholds and a network coupling probability. Agents may possess either one or two information thresholds that, in each case, determine the number of distinct states an agent may occupy before trading takes place. In the case where agents possess two thresholds (labelled as the finite state-space model, corresponding to agents’ accumulating information over a bounded state-space), and where coupling strength is maximal, an asymptotic expression for the cascade-size probability is derived and shown to follow a power law when a critical value of network coupling probability is attained. For a range of model parameters, a mixture of negative binomial distributions is used to approximate the cascade-size distribution. This approximation is subsequently used to express the volatility of model price returns in terms of the model parameter which controls the network coupling probability. In the case where agents possess a single pulse-coupling threshold (labelled as the semi-infinite state-space model corresponding to agents’ accumulating information over an unbounded state-space), numerical evidence is presented that demonstrates volatility clustering and long-memory patterns in the volatility of asset returns. Finally, output from the model is compared to both the distribution of historical stock returns and the market price of an equity index option. PMID:27007236

Adaptive multiscale processing for contrast enhancement

NASA Astrophysics Data System (ADS)

Laine, Andrew F.; Song, Shuwu; Fan, Jian; Huda, Walter; Honeyman, Janice C.; Steinbach, Barbara G.

1993-07-01

This paper introduces a novel approach for accomplishing mammographic feature analysis through overcomplete multiresolution representations. We show that efficient representations may be identified from digital mammograms within a continuum of scale space and used to enhance features of importance to mammography. Choosing analyzing functions that are well localized in both space and frequency, results in a powerful methodology for image analysis. We describe methods of contrast enhancement based on two overcomplete (redundant) multiscale representations: (1) Dyadic wavelet transform (2) (phi) -transform. Mammograms are reconstructed from transform coefficients modified at one or more levels by non-linear, logarithmic and constant scale-space weight functions. Multiscale edges identified within distinct levels of transform space provide a local support for enhancement throughout each decomposition. We demonstrate that features extracted from wavelet spaces can provide an adaptive mechanism for accomplishing local contrast enhancement. We suggest that multiscale detection and local enhancement of singularities may be effectively employed for the visualization of breast pathology without excessive noise amplification.

Stress Energy Tensor in LCFT and LOGARITHMIC Sugawara Construction

NASA Astrophysics Data System (ADS)

Kogan, Ian I.; Nichols, Alexander

We discuss the partners of the stress energy tensor and their structure in Logarithmic conformal field theories. In particular we draw attention to the fundamental differences between theories with zero and non-zero central charge. However they are both characterised by at least two independent parameters. We show how, by using a generalised Sugawara construction, one can calculate the logarithmic partner of T. We show that such a construction works in the c=-2 theory using the conformal dimension one primary currents which generate a logarithmic extension of the Kac-Moody algebra. This is an expanded version of a talk presented by A. Nichols at the conference on Logarithmic Conformal Field Theory and its Applications in Tehran Iran, 2001.

THE LITTLEST HIGGS MODEL AND ONE-LOOP ELECTROWEAK PRECISION CONSTRAINTS.

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

CHEN, M.C.; DAWSON,S.

2004-06-16

We present in this talk the one-loop electroweak precision constraints in the Littlest Higgs model, including the logarithmically enhanced contributions from both fermion and scalar loops. We find the one-loop contributions are comparable to the tree level corrections in some regions of parameter space. A low cutoff scale is allowed for a non-zero triplet VEV. Constraints on various other parameters in the model are also discussed. The role of triplet scalars in constructing a consistent renormalization scheme is emphasized.

Bending energy of buckled edge dislocations

NASA Astrophysics Data System (ADS)

Kupferman, Raz

2017-12-01

The study of elastic membranes carrying topological defects has a longstanding history, going back at least to the 1950s. When allowed to buckle in three-dimensional space, membranes with defects can totally relieve their in-plane strain, remaining with a bending energy, whose rigidity modulus is small compared to the stretching modulus. In this paper we study membranes with a single edge dislocation. We prove that the minimum bending energy associated with strain-free configurations diverges logarithmically with the size of the system.

40 CFR 60.112a - Standard for volatile organic compounds (VOC).

Code of Federal Regulations, 2010 CFR

2010-07-01

... space vents is to provide a projection below the liquid surface. Each opening in the roof except for... for automatic bleeder vents and the rim space vents is to provide a projection below the liquid... for Storage Vessels for Petroleum Liquids for Which Construction, Reconstruction, or Modification...

40 CFR 60.112a - Standard for volatile organic compounds (VOC).

Code of Federal Regulations, 2013 CFR

2013-07-01

... space vents is to provide a projection below the liquid surface. Each opening in the roof except for... for automatic bleeder vents and the rim space vents is to provide a projection below the liquid... for Storage Vessels for Petroleum Liquids for Which Construction, Reconstruction, or Modification...

40 CFR 60.112a - Standard for volatile organic compounds (VOC).

Code of Federal Regulations, 2012 CFR

2012-07-01

... space vents is to provide a projection below the liquid surface. Each opening in the roof except for... for automatic bleeder vents and the rim space vents is to provide a projection below the liquid... for Storage Vessels for Petroleum Liquids for Which Construction, Reconstruction, or Modification...

40 CFR 60.112a - Standard for volatile organic compounds (VOC).

Code of Federal Regulations, 2011 CFR

2011-07-01

... space vents is to provide a projection below the liquid surface. Each opening in the roof except for... for automatic bleeder vents and the rim space vents is to provide a projection below the liquid... for Storage Vessels for Petroleum Liquids for Which Construction, Reconstruction, or Modification...

40 CFR 60.112a - Standard for volatile organic compounds (VOC).

Code of Federal Regulations, 2014 CFR

2014-07-01

... space vents is to provide a projection below the liquid surface. Each opening in the roof except for... for automatic bleeder vents and the rim space vents is to provide a projection below the liquid... for Storage Vessels for Petroleum Liquids for Which Construction, Reconstruction, or Modification...

Effect of sequential surface irrigations on field-scale emissions of 1,3-dichloropropene.

PubMed

Yates, S R; Knuteson, J; Ernst, F F; Zheng, W; Wang, Q

2008-12-01

A field experiment was conducted to measure subsurface movement and volatilization of 1,3-dichloropropene (1,3-D) after shank injection to an agricultural soil. The goal of this study was to evaluate the effect of sprinkler irrigation on the emissions of 1,3-D to the atmosphere and is based on recent research that has shown that saturating the soil pore space reduces gas-phase diffusion and leads to reduced volatilization rates. Aerodynamic, integrated horizontal flux, and theoretical profile shape methods were used to estimate fumigant volatilization rates and total emission losses. These methods provide estimates of the volatilization rate based on measurements of wind speed, temperature, and 1,3-D concentration in the atmosphere. The volatilization rate was measured continuously for 16 days, and the daily peak volatilization rates for the three methods ranged from 18 to 60 microg m(-2) s(-1). The total 13-D mass entering the atmosphere was approximately 44-68 kg ha(-1), or 10-15% of the applied active ingredient This represents approximately 30-50% reduction in the total emission losses compared to conventional fumigant applications in field and field-plot studies. Significant reduction in volatilization of 1,3-D was observed when five surface irrigations were applied to the field, one immediately after fumigation followed by daily irrigations.

Self-organizing systems in planetary physics: Harmonic resonances of planet and moon orbits

NASA Astrophysics Data System (ADS)

Aschwanden, Markus J.

2018-01-01

The geometric arrangement of planet and moon orbits into a regularly spaced pattern of distances is the result of a self-organizing system. The positive feedback mechanism that operates a self-organizing system is accomplished by harmonic orbit resonances, leading to long-term stable planet and moon orbits in solar or stellar systems. The distance pattern of planets was originally described by the empirical Titius-Bode law, and by a generalized version with a constant geometric progression factor (corresponding to logarithmic spacing). We find that the orbital periods Ti and planet distances Ri from the Sun are not consistent with logarithmic spacing, but rather follow the quantized scaling (Ri + 1 /Ri) =(Ti + 1 /Ti) 2 / 3 =(Hi + 1 /Hi) 2 / 3 , where the harmonic ratios are given by five dominant resonances, namely (Hi + 1 :Hi) =(3 : 2) ,(5 : 3) ,(2 : 1) ,(5 : 2) ,(3 : 1) . We find that the orbital period ratios tend to follow the quantized harmonic ratios in increasing order. We apply this harmonic orbit resonance model to the planets and moons in our solar system, and to the exo-planets of 55 Cnc and HD 10180 planetary systems. The model allows us a prediction of missing planets in each planetary system, based on the quasi-regular self-organizing pattern of harmonic orbit resonance zones. We predict 7 (and 4) missing exo-planets around the star 55 Cnc (and HD 10180). The accuracy of the predicted planet and moon distances amounts to a few percents. All analyzed systems are found to have ≈ 10 resonant zones that can be occupied with planets (or moons) in long-term stable orbits.

A Space-Saving Approximation Algorithm for Grammar-Based Compression

NASA Astrophysics Data System (ADS)

Sakamoto, Hiroshi; Maruyama, Shirou; Kida, Takuya; Shimozono, Shinichi

A space-efficient approximation algorithm for the grammar-based compression problem, which requests for a given string to find a smallest context-free grammar deriving the string, is presented. For the input length n and an optimum CFG size g, the algorithm consumes only O(g log g) space and O(n log*n) time to achieve O((log*n)log n) approximation ratio to the optimum compression, where log*n is the maximum number of logarithms satisfying log log…log n > 1. This ratio is thus regarded to almost O(log n), which is the currently best approximation ratio. While g depends on the string, it is known that g =Ω(log n) and g=\\\\Omega(\\\\log n) and g=O\\\\left(\\\\frac{n}{log_kn}\\\\right) for strings from k-letter alphabet[12].

Computing Logarithms by Hand

ERIC Educational Resources Information Center

Reed, Cameron

2016-01-01

How can old-fashioned tables of logarithms be computed without technology? Today, of course, no practicing mathematician, scientist, or engineer would actually use logarithms to carry out a calculation, let alone worry about deriving them from scratch. But high school students may be curious about the process. This article develops a…

RESOLVE's Field Demonstration on Mauna Kea, Hawaii 2010

NASA Technical Reports Server (NTRS)

Captain, Janine; Quinn, Jacqueline; Moss, Thomas; Weis, Kyle

2010-01-01

In cooperation with the Canadian Space Agency, and the Northern Centre for Advanced Technology, Inc., NASA has undertaken the In-Situ Resource Utilization (ISRU) project called RESOLVE (Regolith and Environment Science & Oxygen and Lunar Volatile Extraction). This project is an Earth-based lunar precursor demonstration of a system that could be sent to explore permanently shadowed polar lunar craters, where it would drill into regolith, quantify the volatiles that are present, and extract oxygen by hydrogen reduction of iron oxides. The resulting water could be electrolyzed into oxygen to support exploration and hydrogen, which would be recycled through the process. The RESOLVE chemical processing system was mounted on a Canadian Space Agency mobility chasis and successfully demonstrated on Hawaii's Mauna Kea volcano in February 2010. The RESOLVE unit is the initial prototype of a robotic prospecting mission to the Moon. RESOLVE is designed to go to the poles of the Moon to "ground truth" the form and concentration of the hydrogen/water/hydroxyl that has been seen from orbit (M3, Lunar Prospector and LRO) and to test technologies to extract oxygen from the lunar regolith. RESOLVE has the ability to capture a one-meter core sample of lunar regolith and heat it to determine the volatiles that may be released and then demonstrate the production of oxygen from minerals found in the regolith. The RESOLVE project, which is led by KSC, is a multi-center and multi-organizational effort that includes representatives from KSC, JSC, GRC, the Canadian Space Agency, and the Northern Center for Advanced Technology (NORCAT). This paper details the results obtained from four days of lunar analog testing that included gas chromatograph analysis for volatile components, remote control of chemistry and drilling operations via satalite communications, and real-time water quantification using a novel capacitance measurement technique.

Mars Atmosphere and Volatile Evolution (MAVEN) Mission Design

NASA Technical Reports Server (NTRS)

Folta, David C.

2010-01-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission was selected as the second in the low-cost Mars Scout mission series. MAVEN will determine the role that loss of volatiles to space has played through time from a highly inclined elliptical orbit. The launch period opens November 18. 2013 with arrival September 16, 2014. After achieving a 35-hour capture orbit, maneuvers will reduce the period to 4.5-hours with periapsis near 150 kilometers and maintain the periapsis within a specified density corridor. MAVEN will also execute "Deep Dip" campaigns, with periapsis at an altitude near 125 kilometers. This paper presents the unique mission design challenges of the MAVEN mission.

Logarithmic scaling for fluctuations of a scalar concentration in wall turbulence.

PubMed

Mouri, Hideaki; Morinaga, Takeshi; Yagi, Toshimasa; Mori, Kazuyasu

2017-12-01

Within wall turbulence, there is a sublayer where the mean velocity and the variance of velocity fluctuations vary logarithmically with the height from the wall. This logarithmic scaling is also known for the mean concentration of a passive scalar. By using heat as such a scalar in a laboratory experiment of a turbulent boundary layer, the existence of the logarithmic scaling is shown here for the variance of fluctuations of the scalar concentration. It is reproduced by a model of energy-containing eddies that are attached to the wall.

Mathematical model for logarithmic scaling of velocity fluctuations in wall turbulence.

PubMed

Mouri, Hideaki

2015-12-01

For wall turbulence, moments of velocity fluctuations are known to be logarithmic functions of the height from the wall. This logarithmic scaling is due to the existence of a characteristic velocity and to the nonexistence of any characteristic height in the range of the scaling. By using the mathematics of random variables, we obtain its necessary and sufficient conditions. They are compared with characteristics of a phenomenological model of eddies attached to the wall and also with those of the logarithmic scaling of the mean velocity.

Logarithmic amplifiers.

PubMed

Gandler, W; Shapiro, H

1990-01-01

Logarithmic amplifiers (log amps), which produce an output signal proportional to the logarithm of the input signal, are widely used in cytometry for measurements of parameters that vary over a wide dynamic range, e.g., cell surface immunofluorescence. Existing log amp circuits all deviate to some extent from ideal performance with respect to dynamic range and fidelity to the logarithmic curve; accuracy in quantitative analysis using log amps therefore requires that log amps be individually calibrated. However, accuracy and precision may be limited by photon statistics and system noise when very low level input signals are encountered.

Stress Energy tensor in LCFT and the Logarithmic Sugawara construction

NASA Astrophysics Data System (ADS)

Kogan, Ian I.; Nichols, Alexander

2002-01-01

We discuss the partners of the stress energy tensor and their structure in Logarithmic conformal field theories. In particular we draw attention to the fundamental differences between theories with zero and non-zero central charge. However they are both characterised by at least two independent parameters. We show how, by using a generalised Sugawara construction, one can calculate the logarithmic partner of T. We show that such a construction works in the c = -2 theory using the conformal dimension one primary currents which generate a logarithmic extension of the Kac-Moody algebra.

Equilibrium Solutions of the Logarithmic Hamiltonian Leapfrog for the N-body Problem

NASA Astrophysics Data System (ADS)

Minesaki, Yukitaka

2018-04-01

We prove that a second-order logarithmic Hamiltonian leapfrog for the classical general N-body problem (CGNBP) designed by Mikkola and Tanikawa and some higher-order logarithmic Hamiltonian methods based on symmetric multicompositions of the logarithmic algorithm exactly reproduce the orbits of elliptic relative equilibrium solutions in the original CGNBP. These methods are explicit symplectic methods. Before this proof, only some implicit discrete-time CGNBPs proposed by Minesaki had been analytically shown to trace the orbits of elliptic relative equilibrium solutions. The proof is therefore the first existence proof for explicit symplectic methods. Such logarithmic Hamiltonian methods with a variable time step can also precisely retain periodic orbits in the classical general three-body problem, which generic numerical methods with a constant time step cannot do.

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

Stevens, Mark J.; Saleh, Omar A.

We calculated the force-extension curves for a flexible polyelectrolyte chain with varying charge separations by performing Monte Carlo simulations of a 5000 bead chain using a screened Coulomb interaction. At all charge separations, the force-extension curves exhibit a Pincus-like scaling regime at intermediate forces and a logarithmic regime at large forces. As the charge separation increases, the Pincus regime shifts to a larger range of forces and the logarithmic regime starts are larger forces. We also found that force-extension curve for the corresponding neutral chain has a logarithmic regime. Decreasing the diameter of bead in the neutral chain simulations removedmore » the logarithmic regime, and the force-extension curve tends to the freely jointed chain limit. In conclusion, this result shows that only excluded volume is required for the high force logarithmic regime to occur.« less

Logarithmic M(2,p) minimal models, their logarithmic couplings, and duality

NASA Astrophysics Data System (ADS)

Mathieu, Pierre; Ridout, David

2008-10-01

A natural construction of the logarithmic extension of the M(2,p) (chiral) minimal models is presented, which generalises our previous model of percolation ( p=3). Its key aspect is the replacement of the minimal model irreducible modules by reducible ones obtained by requiring that only one of the two principal singular vectors of each module vanish. The resulting theory is then constructed systematically by repeatedly fusing these building block representations. This generates indecomposable representations of the type which signify the presence of logarithmic partner fields in the theory. The basic data characterising these indecomposable modules, the logarithmic couplings, are computed for many special cases and given a new structural interpretation. Quite remarkably, a number of them are presented in closed analytic form (for general p). These are the prime examples of "gauge-invariant" data—quantities independent of the ambiguities present in defining the logarithmic partner fields. Finally, mere global conformal invariance is shown to enforce strong constraints on the allowed spectrum: It is not possible to include modules other than those generated by the fusion of the model's building blocks. This generalises the statement that there cannot exist two effective central charges in a c=0 model. It also suggests the existence of a second "dual" logarithmic theory for each p. Such dual models are briefly discussed.

Modeling of cytometry data in logarithmic space: When is a bimodal distribution not bimodal?

PubMed

Erez, Amir; Vogel, Robert; Mugler, Andrew; Belmonte, Andrew; Altan-Bonnet, Grégoire

2018-02-16

Recent efforts in systems immunology lead researchers to build quantitative models of cell activation and differentiation. One goal is to account for the distributions of proteins from single-cell measurements by flow cytometry or mass cytometry as readout of biological regulation. In that context, large cell-to-cell variability is often observed in biological quantities. We show here that these readouts, viewed in logarithmic scale may result in two easily-distinguishable modes, while the underlying distribution (in linear scale) is unimodal. We introduce a simple mathematical test to highlight this mismatch. We then dissect the flow of influence of cell-to-cell variability proposing a graphical model which motivates higher-dimensional analysis of the data. Finally we show how acquiring additional biological information can be used to reduce uncertainty introduced by cell-to-cell variability, helping to clarify whether the data is uni- or bimodal. This communication has cautionary implications for manual and automatic gating strategies, as well as clustering and modeling of single-cell measurements. © 2018 International Society for Advancement of Cytometry. © 2018 International Society for Advancement of Cytometry.

Generalization and capacity of extensively large two-layered perceptrons.

PubMed

Rosen-Zvi, Michal; Engel, Andreas; Kanter, Ido

2002-09-01

The generalization ability and storage capacity of a treelike two-layered neural network with a number of hidden units scaling as the input dimension is examined. The mapping from the input to the hidden layer is via Boolean functions; the mapping from the hidden layer to the output is done by a perceptron. The analysis is within the replica framework where an order parameter characterizing the overlap between two networks in the combined space of Boolean functions and hidden-to-output couplings is introduced. The maximal capacity of such networks is found to scale linearly with the logarithm of the number of Boolean functions per hidden unit. The generalization process exhibits a first-order phase transition from poor to perfect learning for the case of discrete hidden-to-output couplings. The critical number of examples per input dimension, alpha(c), at which the transition occurs, again scales linearly with the logarithm of the number of Boolean functions. In the case of continuous hidden-to-output couplings, the generalization error decreases according to the same power law as for the perceptron, with the prefactor being different.

Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station

NASA Astrophysics Data System (ADS)

Bernier, Matthew C.; Alberici, Rosana M.; Keelor, Joel D.; Dwivedi, Prabha; Zambrzycki, Stephen C.; Wallace, William T.; Gazda, Daniel B.; Limero, Thomas F.; Symonds, Josh M.; Orlando, Thomas M.; Macatangay, Ariel; Fernández, Facundo M.

2016-07-01

Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 μm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices.

Microplasma Ionization of Volatile Organics for Improving Air/Water Monitoring Systems On-Board the International Space Station.

PubMed

Bernier, Matthew C; Alberici, Rosana M; Keelor, Joel D; Dwivedi, Prabha; Zambrzycki, Stephen C; Wallace, William T; Gazda, Daniel B; Limero, Thomas F; Symonds, Josh M; Orlando, Thomas M; Macatangay, Ariel; Fernández, Facundo M

2016-07-01

Low molecular weight polar organics are commonly observed in spacecraft environments. Increasing concentrations of one or more of these contaminants can negatively impact Environmental Control and Life Support (ECLS) systems and/or the health of crew members, posing potential risks to the success of manned space missions. Ambient plasma ionization mass spectrometry (MS) is finding effective use as part of the analytical methodologies being tested for next-generation space module environmental analysis. However, ambient ionization methods employing atmospheric plasmas typically require relatively high operation voltages and power, thus limiting their applicability in combination with fieldable mass spectrometers. In this work, we investigate the use of a low power microplasma device in the microhollow cathode discharge (MHCD) configuration for the analysis of polar organics encountered in space missions. A metal-insulator-metal (MIM) structure with molybdenum foil disc electrodes and a mica insulator was used to form a 300 μm diameter plasma discharge cavity. We demonstrate the application of these MIM microplasmas as part of a versatile miniature ion source for the analysis of typical volatile contaminants found in the International Space Station (ISS) environment, highlighting their advantages as low cost and simple analytical devices. Graphical Abstract ᅟ.

Volatile Analyzer for Lunar Polar Missions

NASA Technical Reports Server (NTRS)

Gibons, Everett K.; Pillinger, Colin T.; McKay, David S.; Waugh, Lester J.

2011-01-01

One of the major questions remaining for the future exploration of the Moon by humans concerns the presence of volatiles on our nearest neighbor in space. Observational studies, and investigations involving returned lunar samples and using robotic spacecraft infer the existence of volatile compounds particularly water [1]. It seems very likely that a volatile component will be concentrated at the poles in circumstances where low-temperatures exist to provide cryogenic traps. However, the full inventory of species, their concentration and their origin and sources are unknown. Of particular importance is whether abundances are sufficient to act as a resource of consumables for future lunar expeditions especially if a long-term base involving humans is to be established. To address some of these issues requires a lander designed specifically for operation at a high-lunar latitude. A vital part of the payload needs to be a volatile analyzer such as the Gas Analysis Package specifically designed for identification quantification of volatile substances and collecting information which will allow the origin of these volatiles to be identified [1]. The equipment included, particularly the gas analyzer, must be capable of operation in the extreme environmental conditions to be encountered. No accurate information yet exists regarding volatile concentration even for sites closer to the lunar equator (because of contamination). In this respect it will be important to understand (and thus limit) contamination of the lunar surface by extraneous material contributed from a variety of sources. The only data for the concentrations of volatiles at the poles comes from orbiting spacecraft and whilst the levels at high latitudes may be greater than at the equator, the volatile analyzer package under consideration will be designed to operate at the highest specifications possible and in a way that does not compromise the data.

Free Energy Reconstruction from Logarithmic Mean-Force Dynamics Using Multiple Nonequilibrium Trajectories.

PubMed

Morishita, Tetsuya; Yonezawa, Yasushige; Ito, Atsushi M

2017-07-11

Efficient and reliable estimation of the mean force (MF), the derivatives of the free energy with respect to a set of collective variables (CVs), has been a challenging problem because free energy differences are often computed by integrating the MF. Among various methods for computing free energy differences, logarithmic mean-force dynamics (LogMFD) [ Morishita et al., Phys. Rev. E 2012 , 85 , 066702 ] invokes the conservation law in classical mechanics to integrate the MF, which allows us to estimate the free energy profile along the CVs on-the-fly. Here, we present a method called parallel dynamics, which improves the estimation of the MF by employing multiple replicas of the system and is straightforwardly incorporated in LogMFD or a related method. In the parallel dynamics, the MF is evaluated by a nonequilibrium path-ensemble using the multiple replicas based on the Crooks-Jarzynski nonequilibrium work relation. Thanks to the Crooks relation, realizing full-equilibrium states is no longer mandatory for estimating the MF. Additionally, sampling in the hidden subspace orthogonal to the CV space is highly improved with appropriate weights for each metastable state (if any), which is hardly achievable by typical free energy computational methods. We illustrate how to implement parallel dynamics by combining it with LogMFD, which we call logarithmic parallel dynamics (LogPD). Biosystems of alanine dipeptide and adenylate kinase in explicit water are employed as benchmark systems to which LogPD is applied to demonstrate the effect of multiple replicas on the accuracy and efficiency in estimating the free energy profiles using parallel dynamics.

How Do Students Acquire an Understanding of Logarithmic Concepts?

ERIC Educational Resources Information Center

Mulqueeny, Ellen

2012-01-01

The use of logarithms, an important tool for calculus and beyond, has been reduced to symbol manipulation without understanding in most entry-level college algebra courses. The primary aim of this research, therefore, was to investigate college students' understanding of logarithmic concepts through the use of a series of instructional tasks…

Design of a Programmable Gain, Temperature Compensated Current-Input Current-Output CMOS Logarithmic Amplifier.

PubMed

Ming Gu; Chakrabartty, Shantanu

2014-06-01

This paper presents the design of a programmable gain, temperature compensated, current-mode CMOS logarithmic amplifier that can be used for biomedical signal processing. Unlike conventional logarithmic amplifiers that use a transimpedance technique to generate a voltage signal as a logarithmic function of the input current, the proposed approach directly produces a current output as a logarithmic function of the input current. Also, unlike a conventional transimpedance amplifier the gain of the proposed logarithmic amplifier can be programmed using floating-gate trimming circuits. The synthesis of the proposed circuit is based on the Hart's extended translinear principle which involves embedding a floating-voltage source and a linear resistive element within a translinear loop. Temperature compensation is then achieved using a translinear-based resistive cancelation technique. Measured results from prototypes fabricated in a 0.5 μm CMOS process show that the amplifier has an input dynamic range of 120 dB and a temperature sensitivity of 230 ppm/°C (27 °C- 57°C), while consuming less than 100 nW of power.

Factorization for jet radius logarithms in jet mass spectra at the LHC

DOE PAGES

Kolodrubetz, Daniel W.; Pietrulewicz, Piotr; Stewart, Iain W.; ...

2016-12-14

To predict the jet mass spectrum at a hadron collider it is crucial to account for the resummation of logarithms between the transverse momentum of the jet and its invariant mass m J . For small jet areas there are additional large logarithms of the jet radius R, which affect the convergence of the perturbative series. We present an analytic framework for exclusive jet production at the LHC which gives a complete description of the jet mass spectrum including realistic jet algorithms and jet vetoes. It factorizes the scales associated with m J , R, and the jet veto, enablingmore » in addition the systematic resummation of jet radius logarithms in the jet mass spectrum beyond leading logarithmic order. We discuss the factorization formulae for the peak and tail region of the jet mass spectrum and for small and large R, and the relations between the different regimes and how to combine them. Regions of experimental interest are classified which do not involve large nonglobal logarithms. We also present universal results for nonperturbative effects and discuss various jet vetoes.« less

How Cold are the Floors of Lunar Polar Shadowed Craters?

NASA Technical Reports Server (NTRS)

Mendell, Wendell W.

2010-01-01

Almost five decades ago Watson, et al, [1] speculated that molecules of volatile species might accumulate within the cryogenic environments of permanently shadowed polar craters. The subject was largely a scientific curiosity until recently. In the mid-1980's, people began to seriously discuss the feasibility of long-term or permanent human settlement of the Moon. Given that the Moon was known be missing the compounds need to support life and that importing volatiles from Earth is prohibitively expensive, lunar colonists were pictured as processing the putative polar volatiles. A bistatic radar experiment performed with the Clementine spacecraft was interpreted to suggest the presence of large quantities of ice at some polar locations. [2] The neutron spectrometer aboard the Lunar Prospector spacecraft reported high concentrations of hydrogen in the polar regolith, [3] and some interpretations of the data set pointed to very high concentrations in permanently shadowed craters. The reformulation of civilian space policy in 2004, known as the Vision for Space Exploration, emphasized lunar exploration with eye toward development of economic returns from cislunar space and long-tern human presence on the Moon. The theme of finding lunar resources was an impetus for the inclusion of the Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter. Preliminary results from Diviner report an unexpectedly low temperature down to 35K in the depths of some craters. [4

Real-time science operations to support a lunar polar volatiles rover mission

NASA Astrophysics Data System (ADS)

Heldmann, Jennifer L.; Colaprete, Anthony; Elphic, Richard C.; Mattes, Greg; Ennico, Kimberly; Fritzler, Erin; Marinova, Margarita M.; McMurray, Robert; Morse, Stephanie; Roush, Ted L.; Stoker, Carol R.

2015-05-01

Future human exploration of the Moon will likely rely on in situ resource utilization (ISRU) to enable long duration lunar missions. Prior to utilizing ISRU on the Moon, the natural resources (in this case lunar volatiles) must be identified and characterized, and ISRU demonstrated on the lunar surface. To enable future uses of ISRU, NASA and the CSA are developing a lunar rover payload that can (1) locate near subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form, extractability and usefulness of the materials. Such investigations are important both for ISRU purposes and for understanding the scientific nature of these intriguing lunar volatile deposits. Temperature models and orbital data suggest near surface volatile concentrations may exist at briefly lit lunar polar locations outside persistently shadowed regions. A lunar rover could be remotely operated at some of these locations for the ∼ 2-14 days of expected sunlight at relatively low cost. Due to the limited operational time available, both science and rover operations decisions must be made in real time, requiring immediate situational awareness, data analysis, and decision support tools. Given these constraints, such a mission requires a new concept of operations. In this paper we outline the results and lessons learned from an analog field campaign in July 2012 which tested operations for a lunar polar rover concept. A rover was operated in the analog environment of Hawaii by an off-site Flight Control Center, a rover navigation center in Canada, a Science Backroom at NASA Ames Research Center in California, and support teams at NASA Johnson Space Center in Texas and NASA Kennedy Space Center in Florida. We find that this type of mission requires highly efficient, real time, remotely operated rover operations to enable low cost, scientifically relevant exploration of the distribution and nature of lunar polar volatiles. The field demonstration illustrated the need for science operations personnel in constant communications with the flight mission operators and the Science Backroom to provide immediate and continual science support and validation throughout the mission. Specific data analysis tools are also required to enable immediate data monitoring, visualization, and decision making. The field campaign demonstrated that this novel methodology of real-time science operations is possible and applicable to providing important new insights regarding lunar polar volatiles for both science and exploration.

Real-Time Science Operations to Support a Lunar Polar Volatiles Rover Mission

NASA Technical Reports Server (NTRS)

Heldmann, Jennifer L.; Colaprete, Anthony; Elphic, Richard C.; Mattes, Greg; Ennico, Kimberly; Fritzler, Erin; Marinova, Margarita M.; McMurray, Robert; Morse, Stephanie; Roush, Ted L.;

History of Martian Atmosphere and Volatiles Derived From MAVEN Observations

NASA Astrophysics Data System (ADS)

Jakosky, B. M.

2017-12-01

The MAVEN spacecraft has been observing loss of volatiles from the Mars upper atmosphere to space for more than a full Mars year. By understanding the present-day loss rates and the processes that drive loss, we can extrapolate to past epochs and estimate the total amount of gas lost to space through time. The current total loss rate is more than 2 kg/s. With the increased loss rate in the past due to the greater solar EUV flux and solar-wind intensity early in history, we estimate that more than 0.5 bar of CO2 might have been lost to space. This plausibility argument is augmented by observations of the 38Ar/36Ar ratio today that provide a direct indication of the integrated loss through time; the measurements indicate that the majority of atmospheric gas has, in fact, been lost to space. Combined with the lack of carbonates on the surface that can be a reservoir for CO2 from an earlier, thick atmosphere, these results point to loss to space as having been the major process for driving the changes in the atmosphere. Loss to space appears to have been responsible for changing the Martian climate from an early, warm, wet environment to the cold, dry climate that we see today.

Programming of the complex logarithm function in the solution of the cracked anisotropic plate loaded by a point force

NASA Astrophysics Data System (ADS)

Zaal, K. J. J. M.

1991-06-01

In programming solutions of complex function theory, the complex logarithm function is replaced by the complex logarithmic function, introducing a discontinuity along the branch cut into the programmed solution which was not present in the mathematical solution. Recently, Liaw and Kamel presented their solution of the infinite anisotropic centrally cracked plate loaded by an arbitrary point force, which they used as Green's function in a boundary element method intended to evaluate the stress intensity factor at the tip of a crack originating from an elliptical home. Their solution may be used as Green's function of many more numerical methods involving anisotropic elasticity. In programming applications of Liaw and Kamel's solution, the standard definition of the logarithmic function with the branch cut at the nonpositive real axis cannot provide a reliable computation of the displacement field for Liaw and Kamel's solution. Either the branch cut should be redefined outside the domain of the logarithmic function, after proving that the domain is limited to a part of the plane, or the logarithmic function should be defined on its Riemann surface. A two dimensional line fractal can provide the link between all mesh points on the plane essential to evaluate the logarithm function on its Riemann surface. As an example, a two dimensional line fractal is defined for a mesh once used by Erdogan and Arin.

Influence of foam structure on the release kinetics of volatiles from espresso coffee prior to consumption.

PubMed

Dold, Susanne; Lindinger, Christian; Kolodziejczyk, Eric; Pollien, Philippe; Ali, Santo; Germain, Juan Carlos; Perin, Sonia Garcia; Pineau, Nicolas; Folmer, Britta; Engel, Karl-Heinz; Barron, Denis; Hartmann, Christoph

2011-10-26

The relationship between the physical structure of espresso coffee foam, called crema, and the above-the-cup aroma release was studied. Espresso coffee samples were produced using the Nespresso extraction system. The samples were extracted with water with different levels of mineral content, which resulted in liquid phases with similar volatile profiles but foams with different structure properties. The structure parameters foam volume, foam drainage, and lamella film thickness at the foam surface were quantified using computer-assisted microscopic image analysis and a digital caliper. The above-the-cup volatile concentration was measured online by using PTR-MS and headspace sampling. A correlation study was done between crema structure parameters and above-the-cup volatile concentration. In the first 2.5 min after the start of the coffee extraction, the presence of foam induced an increase of concentration of selected volatile markers, independently if the crema was of high or low stability. At times longer than 2.5 min, the aroma marker concentration depends on both the stability of the crema and the volatility of the specific aroma compounds. Mechanisms of above-the-cup volatile release involved gas bubble stability, evaporation, and diffusion. It was concluded that after the initial aroma burst (during the first 2-3 min after the beginning of extraction), for the present sample space a crema of high stability provides a stronger aroma barrier over several minutes.

Lunar volcanism produced a transient atmosphere around the ancient Moon

NASA Astrophysics Data System (ADS)

Needham, Debra H.; Kring, David A.

2017-11-01

Studies of the lunar atmosphere have shown it to be a stable, low-density surface boundary exosphere for the last 3 billion years. However, substantial volcanic activity on the Moon prior to 3 Ga may have released sufficient volatiles to form a transient, more prominent atmosphere. Here, we calculate the volume of mare basalt emplaced as a function of time, then estimate the corresponding production of volatiles released during the mare basalt-forming eruptions. Results indicate that during peak mare emplacement and volatile release ∼3.5 Ga, the maximum atmospheric pressure at the lunar surface could have reached ∼1 kPa, or ∼1.5 times higher than Mars' current atmospheric surface pressure. This lunar atmosphere may have taken ∼70 million years to fully dissipate. Most of the volatiles released by mare basalts would have been lost to space, but some may have been sequestered in permanently shadowed regions on the lunar surface. If only 0.1% of the mare water vented during these eruptions remains in the polar regions of the Moon, volcanically-derived volatiles could account for all hydrogen deposits - suspected to be water - currently observed in the Moon's permanently shadowed regions. Future missions to such locations may encounter evidence of not only asteroidal, cometary, and solar wind-derived volatiles, but also volatiles vented from the interior of the Moon.

Quantification of selected volatile organic compounds in human urine by gas chromatography selective reagent ionization time of flight mass spectrometry (GC-SRI-TOF-MS) coupled with head-space solid-phase microextraction (HS-SPME).

PubMed

Mochalski, Paweł; Unterkofler, Karl

2016-08-07

Selective reagent ionization time of flight mass spectrometry with NO(+) as the reagent ion (SRI-TOF-MS(NO(+))) in conjunction with gas chromatography (GC) and head-space solid-phase microextraction (HS-SPME) was used to determine selected volatile organic compounds in human urine. A total of 16 volatiles exhibiting high incidence rates were quantified in the urine of 19 healthy volunteers. Amongst them there were ten ketones (acetone, 2-butanone, 3-methyl-2-butanone, 2-pentanone, 3-methyl-2-pentanone, 4-methyl-2-pentanone, 2-hexanone, 3-hexanone, 2-heptanone, and 4-heptanone), three volatile sulphur compounds (dimethyl sulfide, allyl methyl sulfide, and methyl propyl sulfide), and three heterocyclic compounds (furan, 2-methylfuran, 3-methylfuran). The concentrations of the species under study varied between 0.55 nmol L(-1) (0.05 nmol mmol(-1)creatinine) for allyl methyl sulfide and 11.6 μmol L(-1) (1.54 μmol mmol(-1)creatinine) for acetone considering medians. Limits of detection (LODs) ranged from 0.08 nmol L(-1) for allyl methyl sulfide to 1.0 nmol L(-1) for acetone and furan (with RSDs ranging from 5 to 9%). The presented experimental setup assists both real-time and GC analyses of volatile organic compounds, which can be performed consecutively using the same analytical system. Such an approach supports the novel concept of hybrid volatolomics, an approach which combines VOC profiles obtained from two or more body fluids to improve and complement the chemical information on the physiological status of an individual.

Volatiles Evolved from Soybean Products Intended for Use in Long Duration Space Missions

NASA Technical Reports Server (NTRS)

Vodovotz, Yael; Bourland, Charles T.

1999-01-01

Soybeans have been baselined to be grown in a habitat (Advanced Life Support Systems Integration Test Bed, ALSSITB) intended for evaluating advanced life support systems developed for long duration missions to the Moon or Mars. The ALSSITB is being constructed at NASA-Johnson Space Center and is composed of 5 chambers (4.6 m x 11.3 m each) and an airlock joined by an interconnecting tunnel (3.7 m x 19.2 m). Processed soy products such as soy milk and soy bread are planned to be incorporated into a nutritionally sound, plant-based food system. Since all consumables will be recycled and reused, volatile compounds evolved during the manufacturing of these food products need to be quantified to assess their impact on this closed loop system. Soy milk was made in a prototype machine and bread in a commercial bread baking machine. These machines were each placed in a tightly closed chamber and, at the completion of the process, air volatiles were identified and quantified by GC/MS. For soy milk, ethanol, acetaldehyde, methanol, hexanal, propanal and acetone and for soybread, acetaldehyde, ethanol, N-propanol and ethyl acetate were detected in significant quantities. The crew members will spend an average of 180 days in the ALSSITB and it was estimated that 138 batches of soy milk will be processed in the tunnel and 130 loaves of soybread would be baked in the habitat chamber during their stay. The aforementioned volatiles would surpass the 180 day Spacecraft Maximum Allowable Concentrations (SMACs) if no means of scrubbing are adapted which would lead to toxic levels of these compounds. Therefore, sufficient means for eliminating the contribution of volatiles evolved from food processing and preparation equipment needs to be provided in the ALSSITB.

Release and uptake of volatile organic compounds by human hepatocellular carcinoma cells (HepG2) in vitro

PubMed Central

2013-01-01

Background Volatile organic compounds (VOCs) emitted by human body offer a unique insight into biochemical processes ongoing in healthy and diseased human organisms. Unfortunately, in many cases their origin and metabolic fate have not been yet elucidated in sufficient depth, thus limiting their clinical application. The primary goal of this work was to identify and quantify volatile organic compounds being released or metabolized by HepG2 hepatocellular carcinoma cells. Methods The hepatocellular carcinoma cells were incubated in specially designed head-space 1-L glass bottles sealed for 24 hours prior to measurements. Identification and quantification of volatiles released and consumed by cells under study were performed by gas chromatography with mass spectrometric detection (GC-MS) coupled with head-space needle trap device extraction (HS-NTD) as the pre-concentration technique. Most of the compounds were identified both by spectral library match as well as retention time comparison based on standards. Results A total of nine compounds were found to be metabolised and further twelve released by the cells under study (Wilcoxon signed-rank test, p<0.05). The former group comprised 6 aldehydes (2-methyl 2-propenal, 2-methyl propanal, 2-ethylacrolein, 3-methyl butanal, n-hexanal and benzaldehyde), n-propyl propionate, n-butyl acetate, and isoprene. Amongst the released species there were five ketones (2-pentanone, 3-heptanone, 2-heptanone, 3-octanone, 2-nonanone), five volatile sulphur compounds (dimethyl sulfide, ethyl methyl sulfide, 3-methyl thiophene, 2-methyl-1-(methylthio)- propane and 2-methyl-5-(methylthio) furan), n-propyl acetate, and 2-heptene. Conclusions The emission and uptake of the aforementioned VOCs may reflect the activity of abundant liver enzymes and support the potential of VOC analysis for the assessment of enzymes function. PMID:23870484

Non-Volatile Memory Technology Symposium 2001: Proceedings

NASA Technical Reports Server (NTRS)

Aranki, Nazeeh; Daud, Taher; Strauss, Karl

2001-01-01

This publication contains the proceedings for the Non-Volatile Memory Technology Symposium 2001 that was held on November 7-8, 2001 in San Diego, CA. The proceedings contains a a wide range of papers that cover current and new memory technologies including Flash memories, Magnetic Random Access Memories (MRAM and GMRAM), Ferro-electric RAM (FeRAM), and Chalcogenide RAM (CRAM). The papers presented in the proceedings address the use of these technologies for space applications as well as radiation effects and packaging issues.

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

Birmingham, D.; Kantowski, R.; Milton, K.A.

We use two methods of computing the unique logarithmically divergent part of the Casimir energy for massive scalar and spinor fields defined on even-dimensional Kaluza-Klein spaces of the form M/sup 4/ x S/sup N//sup 1/ x S/sup N//sup 2/ x xxx. Both methods (heat kernel and direct) give identical results. The first evaluates the required internal zeta function by identifying it in the asymptotic expansion of the trace of the heat kernel, and the second evaluates the zeta function directly using the Euler-Maclaurin sum formula. In Appendix C we tabulate these energies for all spaces of total internal dimension lessmore » than or equal to6. These methods are easily applied to vector and tensor fields needed in computing one-loop vacuum gravitational energies on these spaces. Stable solutions are given for internal structure S/sup 2/ x S/sup 2/.« less

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

Dehesa, J.S.; Martinez-Finkelshtein, A.; Sorokin, V.N.

The asymptotics of the Boltzmann-Shannon information entropy as well as the Renyi entropy for the quantum probability density of a single-particle system with a confining (i.e., bounded below) power-type potential V(x)=x{sup 2k} with k is a member of N and x is a member of R, is investigated in the position and momentum spaces within the semiclassical (WKB) approximation. It is found that for highly excited states both physical entropies, as well as their sum, have a logarithmic dependence on its quantum number not only when k=1 (harmonic oscillator), but also for any fixed k. As a by-product, the extremalmore » case k{yields}{infinity} (the infinite well potential) is also rigorously analyzed. It is shown that not only the position-space entropy has the same constant value for all quantum states, which is a known result, but also that the momentum-space entropy is constant for highly excited states.« less

Renormalization of position space amplitudes in a massless QFT

NASA Astrophysics Data System (ADS)

Todorov, Ivan

2017-03-01

Ultraviolet renormalization of position space massless Feynman amplitudes has been shown to yield associate homogeneous distributions. Their degree is determined by the degree of divergence while their order—the highest power of logarithm in the dilation anomaly—is given by the number of (sub)divergences. In the present paper we review these results and observe that (convergent) integration over internal vertices does not alter the total degree of (superficial) ultraviolet divergence. For a conformally invariant theory internal integration is also proven to preserve the order of associate homogeneity. The renormalized 4-point amplitudes in the φ4 theory (in four space-time dimensions) are written as (non-analytic) translation invariant functions of four complex variables with calculable conformal anomaly. Our conclusion concerning the (off-shell) infrared finiteness of the ultraviolet renormalized massless φ4 theory agrees with the old result of Lowenstein and Zimmermann [23].

[Substantiation of medical-engineering specifications for polymethyl siloxane removal by life support systems].

PubMed

Pakhomova, A A; Aksel'-Rubinshteĭn, V Z; Mikos, K N; Nikitin, E I

2009-01-01

Analysis of experimental data about the quantitative and qualitative chemical make-up of air in the orbital station Mir and International space station (ISS) showed a permanent presence of silicon. The main source of silicon contaminants seems to be a variety of polymethyl siloxane liquids and siloxane coating of electronics. The article describes the volatile silicon contaminants detected in space stations air. To control concentrations of silicon, the existing air purification system needs to be augmented with carbons having the micropore entrance larger than diameters of silicon-containing molecules. It is also important to elaborate the technology of polymethyl siloxane liquids synthesis so as to reduce the amount of volatile admixtures emission and to observe rigorously the pre-flight off-gassing requirements with special concern about silicon coatings.

FORTRAN plotting subroutines for the space plasma laboratory

NASA Technical Reports Server (NTRS)

Williams, R.

1983-01-01

The computer program known as PLOTRW was custom made to satisfy some of the graphics requirements for the data collected in the Space Plasma Laboratory at the Johnson Space Center (JSC). The general requirements for the program were as follows: (1) all subroutines shall be callable through a FORTRAN source program; (2) all graphs shall fill one page and be properly labeled; (3) there shall be options for linear axes and logarithmic axes; (4) each axis shall have tick marks equally spaced with numeric values printed at the beginning tick mark and at the last tick mark; and (5) there shall be three options for plotting. These are: (1) point plot, (2) line plot and (3) point-line plot. The subroutines were written in FORTRAN IV for the LSI-11 Digital equipment Corporation (DEC) Computer. The program is now operational and can be run on any TEKTRONICX graphics terminal that uses a DEC Real-Time-11 (RT-11) operating system.

Simulations of stretching a flexible polyelectrolyte with varying charge separation

DOE PAGES

Stevens, Mark J.; Saleh, Omar A.

2016-07-22

We calculated the force-extension curves for a flexible polyelectrolyte chain with varying charge separations by performing Monte Carlo simulations of a 5000 bead chain using a screened Coulomb interaction. At all charge separations, the force-extension curves exhibit a Pincus-like scaling regime at intermediate forces and a logarithmic regime at large forces. As the charge separation increases, the Pincus regime shifts to a larger range of forces and the logarithmic regime starts are larger forces. We also found that force-extension curve for the corresponding neutral chain has a logarithmic regime. Decreasing the diameter of bead in the neutral chain simulations removedmore » the logarithmic regime, and the force-extension curve tends to the freely jointed chain limit. In conclusion, this result shows that only excluded volume is required for the high force logarithmic regime to occur.« less

Improved maximum average correlation height filter with adaptive log base selection for object recognition

NASA Astrophysics Data System (ADS)

Tehsin, Sara; Rehman, Saad; Awan, Ahmad B.; Chaudry, Qaiser; Abbas, Muhammad; Young, Rupert; Asif, Afia

2016-04-01

Sensitivity to the variations in the reference image is a major concern when recognizing target objects. A combinational framework of correlation filters and logarithmic transformation has been previously reported to resolve this issue alongside catering for scale and rotation changes of the object in the presence of distortion and noise. In this paper, we have extended the work to include the influence of different logarithmic bases on the resultant correlation plane. The meaningful changes in correlation parameters along with contraction/expansion in the correlation plane peak have been identified under different scenarios. Based on our research, we propose some specific log bases to be used in logarithmically transformed correlation filters for achieving suitable tolerance to different variations. The study is based upon testing a range of logarithmic bases for different situations and finding an optimal logarithmic base for each particular set of distortions. Our results show improved correlation and target detection accuracies.

Integrated Impacts of environmental factors on the degradation of fumigants

NASA Astrophysics Data System (ADS)

Lee, J.; Yates, S. R.

2007-12-01

Volatilization of fumigants has been concerned as one of air pollution sources. Fumigants are used to control nematodes and soil-born pathogens for a pre-plant treatment to increase the production of high-cash crops. One of technologies to reduce the volatilization of fumigants to atmosphere is to enhance the degradation of fumigants in soil. Fumigant degradation is affected by environmental factors such as moisture content, temperature, initial concentration of injected fumigants, and soil properties. However, effects of each factor on the degradation were limitedly characterized and integrated Impacts from environmental factors has not been described yet. Degradation of 1,3- dichloropropene (1,3-D) was investigated in various condition of temperatures (20-60 °C), moisture contents (0 ¡V 30 %) and initial concentrations (0.6 ¡V 60 mg/kg) with Arlington sandy loam soil. Abiotic and biotic degradation processes were distinguished using two sterilization methods with HgCl2 and autoclave and impacts of environmental factors were separately assessed for abiotic and biotic degradations. Initially, degradation rates (k) of cis and trans 1,3-D isomers were estimated by first-order kinetics and modified depending on impacts from environmental factors. Arrhenius equation and Walker¡¦s equation which were conventionally used to describe temperature and moisture effects on degradation were assessed for integrated impacts from environmental factors and logarithmical correlation was observed between initial concentrations of applied fumigants and degradation rates. Understanding integrated impacts of environmental factors on degradation will help to design more effective emission reduction schemes in various conditions and provide more practical parameters for modeling simulations.

Music, Policy, and Place-Centered Education: Finding Space for Adaptability

ERIC Educational Resources Information Center

Schmidt, Patrick K.

2012-01-01

As a volatile educative space, musical education must be interwoven with other concerns and other more encompassing constructs if it is to build robust, meaningful, and complex learning outcomes. This paper attempts to do this by placing music education and a complex understanding of policy side by side, and outlining what people can learn from…

NASA Space Engineering Research Center for utilization of local planetary resources

NASA Technical Reports Server (NTRS)

1992-01-01

Reports covering the period from 1 Nov. 1991 to 31 Oct. 1992 and documenting progress at the NASA Space Engineering Research Center are included. Topics covered include: (1) processing of propellants, volatiles, and metals; (2) production of structural and refractory materials; (3) system optimization discovery and characterization; (4) system automation and optimization; and (5) database development.

Leading chiral logarithms for the nucleon mass

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

Vladimirov, Alexey A.; Bijnens, Johan

2016-01-22

We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the LLog series for the nucleon mass within the heavy baryon theory. The presented results are the first example of LLog calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass.

Robust Bioinformatics Recognition with VLSI Biochip Microsystem

NASA Technical Reports Server (NTRS)

Lue, Jaw-Chyng L.; Fang, Wai-Chi

2006-01-01

A microsystem architecture for real-time, on-site, robust bioinformatic patterns recognition and analysis has been proposed. This system is compatible with on-chip DNA analysis means such as polymerase chain reaction (PCR)amplification. A corresponding novel artificial neural network (ANN) learning algorithm using new sigmoid-logarithmic transfer function based on error backpropagation (EBP) algorithm is invented. Our results show the trained new ANN can recognize low fluorescence patterns better than the conventional sigmoidal ANN does. A differential logarithmic imaging chip is designed for calculating logarithm of relative intensities of fluorescence signals. The single-rail logarithmic circuit and a prototype ANN chip are designed, fabricated and characterized.

Mammalian Toxicity of Munition Compounds. Phase III. Effects of Lifetime Exposure. Part I. 2,4-Dinitrotoluene

DTIC Science & Technology

1979-11-01

systemic and local . B. Basic Protocol 1. Dose Levels and Treatment We usually had a control group and three treatment groups, spaced at equal logarithmic...ad libitum. At the end of 24 hr, the rats were anesthetized with ether and blood was collected from the abdominal aorta. Various tissues were removed...1 3 1 1 Portal inflamation 1I 1 1 1 Focal necrosis 2 2 Patty change 1 1 1 CYOSAj,• flex.a~lLir,- - - Spleen Xxtramedullary hematopoi•sis I Excessive

Reconstructing free-energy landscapes for nonequilibrium periodic potentials

NASA Astrophysics Data System (ADS)

López-Alamilla, N. J.; Jack, Michael W.; Challis, K. J.

2018-03-01

We present a method for reconstructing the free-energy landscape of overdamped Brownian motion on a tilted periodic potential. Our approach exploits the periodicity of the system by using the k -space form of the Smoluchowski equation and we employ an iterative approach to determine the nonequilibrium tilt. We reconstruct landscapes for a number of example potentials to show the applicability of the method to both deep and shallow wells and near-to- and far-from-equilibrium regimes. The method converges logarithmically with the number of Fourier terms in the potential.

The Fractal Nature of Wood Revealed by Drying

DTIC Science & Technology

2000-01-01

structure of pore space. Take the natural 298 Table 1. The fractal dimensions of Ginkgo and Chinese chestnut obtained at varable temperatures species 200C 400...C 600C 800C 1000C Ginkgo 2.106 2.547 2.851 2.863 2.876 Chinese chestnut 2.008 2.566 2.814 2.896 2.972 logarithm of both sides of Eq. (2) and we have...The materials for this investigation came from two species, one was a 37-year- old plantation-grown Ginkgo ( Ginkgo biloba) and the other was a 48-year

Transport characteristics in Au/pentacene/Au diodes

NASA Astrophysics Data System (ADS)

Hayashi, Toshiaki; Naka, Akiyoshi; Hiroki, Masanobu; Yokota, Tomoyuki; Someya, Takao; Fujiwara, Akira

2018-03-01

We have used scanning and transmission electron microscopes (SEM and TEM) to study the structure of a pentacene thin film grown on a Au layer with and shown that it consists of randomly oriented amorphous pentacene clusters. We have also investigated the transport properties of amorphous pentacene in a metal-semiconductor-metal (MSM) diode structure and shown that the current is logarithmically proportional to the square root of the applied voltage, which indicates that transport occurs as the result of hopping between localized sites randomly distributed in space and energy.

Volatile elements - water, carbon, nitrogen, noble gases - on Earth

NASA Astrophysics Data System (ADS)

Marty, B.

2017-12-01

Understanding the origin and evolution of life-bearing volatile elements (water, carbon, nitrogen) on Earth is a fruitful and debated area of research. In his pioneering work, W.W. Rubey inferred that the terrestrial atmosphere and the oceans formed from degassing of the mantle through geological periods of time. Early works on noble gas isotopes were consistent with this view and proposed a catastrophic event of mantle degassing early in Earth's history. We now have evidence, mainly from noble gas isotopes, that several cosmochemical sources contributed water and other volatiles at different stages of Earth's accretion. Potential contributors include the protosolar nebula gas that equilibrated with magma oceans, inner solar system bodies now represented by chondrites, and comets. Stable isotope ratios suggest volatiles where primarily sourced by planetary bodies from the inner solar system. However, recent measurements by the European Space Agency Rosetta probe on the coma of Comet 67P/Churyumov-Gerasimenko permit to set quantitative constraints on the cometary contribution to the surface of our planet. The surface and mantle reservoirs volatile elements exchanged volatile elements through time, with rates that are still uncertain. Some mantle regions remained isolated from whole mantle convection within the first tens to hundreds million years after start of solar system formation. These regions, now sampled by some mantle plumes (e.g., Iceland, Eifel) preserved their volatile load, as indicated by extinct and extant radioactivity systems. The abundance of volatile elements in the mantle is still not well known. Different approaches, such as high pressure experimental petrology, noble gas geochemistry, modelling, resulted in somewhat contrasted estimates, varying over one order of magnitude for water. Comparative planetology, that is, the study of volatiles on the Moon, Venus, Mars, Vesta, will shed light on the sources and strengths of these elements in the inner solar system.

Review of radiation effects on ReRAM devices and technology

NASA Astrophysics Data System (ADS)

Gonzalez-Velo, Yago; Barnaby, Hugh J.; Kozicki, Michael N.

2017-08-01

A review of the ionizing radiation effects on resistive random access memory (ReRAM) technology and devices is presented in this article. The review focuses on vertical devices exhibiting bipolar resistance switching, devices that have already exhibited interesting properties and characteristics for memory applications and, in particular, for non-volatile memory applications. Non-volatile memories are important devices for any type of electronic and embedded system, as they are for space applications. In such applications, specific environmental issues related to the existence of cosmic rays and Van Allen radiation belts around the Earth contribute to specific failure mechanisms related to the energy deposition induced by such ionizing radiation. Such effects are important in non-volatile memory as the current leading technology, i.e. flash-based technology, is sensitive to the total ionizing dose (TID) and single-event effects. New technologies such as ReRAM, if competing with or complementing the existing non-volatile area of memories from the point of view of performance, also have to exhibit great reliability for use in radiation environments such as space. This has driven research on the radiation effects of such ReRAM technology, on both the conductive-bridge RAM as well as the valence-change memories, or OxRAM variants of the technology. Initial characterizations of ReRAM technology showed a high degree of resilience to TID, developing researchers’ interest in characterizing such resilience as well as investigating the cause of such behavior. The state of the art of such research is reviewed in this article.

Volatilization of pesticides from the bare soil surface: evaluation of the humidity effect.

PubMed

Schneider, Martina; Endo, Satoshi; Goss, Kai-Uwe

2013-01-01

Volatilization of pesticides from soils under dry conditions (water content below the permanent wilting point) can be significantly influenced by sorption to hydrated mineral surfaces. This sorption process strongly depends on the water activity, expressed as equilibrium relative humidity in the pore space of the soil, and on the available surface area of the hydrated minerals. In this study, the influence of different humidity regimes on the volatilization of two pesticides (triallate and trifluralin) was demonstrated with a bench-scale wind tunnel system that allowed the establishment of well controlled humidity conditions within the soil. In the experiment starting with very dry conditions, increasing the relative humidity in the adjacent air from 60 to 85% resulted in an up to 8 times higher volatilization rate of the pesticides. An additional strong increase in volatilization (up to 3 times higher) was caused by a simulated rain event, which eliminates all sorption sites associated to mineral surfaces. In agreement with this interpretation, the comparison of two soils suggested that mineral surface area was the soil property that governs the volatilization under dry conditions, whereas soil organic matter was the controlling variable under wet conditions. In contrast to expectations, the use of a novel capsulated suspension for triallate showed the same humidity effects and no substantially lower volatilization rates in comparison to the regular formulation. This study demonstrated that humidity effects on pesticide volatilization can be interpreted via the mechanism of sorption to mineral surfaces under dry conditions. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Effect of crop development on biogenic emissions from plant populations grown in closed plant growth chambers

NASA Technical Reports Server (NTRS)

Batten, J. H.; Stutte, G. W.; Wheeler, R. M.

1995-01-01

The Biomass Production Chamber at John F. Kennedy Space Center is a closed plant growth chamber facility that can be used to monitor the level of biogenic emissions from large populations of plants throughout their entire growth cycle. The head space atmosphere of a 26-day-old lettuce (Lactuca sativa cv. Waldmann's Green) stand was repeatedly sampled and emissions identified and quantified using GC-mass spectrometry. Concentrations of dimethyl sulphide, carbon disulphide, alpha-pinene, furan and 2-methylfuran were not significantly different throughout the day; whereas, isoprene showed significant differences in concentration between samples collected in light and dark periods. Volatile organic compounds from the atmosphere of wheat (Triticum aestivum cv. Yecora Rojo) were analysed and quantified from planting to maturity. Volatile plant-derived compounds included 1-butanol, 2-ethyl-1-hexanol, nonanal, benzaldehyde, tetramethylurea, tetramethylthiourea, 2-methylfuran and 3-methylfuran. Concentrations of volatiles were determined during seedling establishment, vegetative growth, anthesis, grain fill and senescence and found to vary depending on the developmental stage. Atmospheric concentrations of benzaldehyde and nonanal were highest during anthesis, 2-methylfuran and 3-methylfuran concentrations were greatest during grain fill, and the concentration of the tetramethylurea peaked during senescence.

Reconciling Gases With Glasses: Magma Degassing, Overturn and Mixing at Kilauea Volcano, Hawai`i

NASA Astrophysics Data System (ADS)

Edmonds, M.; Gerlach, T. M.

2006-12-01

Our understanding of the volatile budget at Kilauea Volcano is based on measurements of the abundance of volatile elements in volcanic glasses and gases. Observations of volcanic gases gave rise to a fundamental model describing volatile fractionation between the summit and rift zone during the current eruption [Gerlach and Graeber, 1985]. Other workers' analysis of glasses from the Puna Ridge, Kilauea Iki and Pu`u `O`o indicate that magma degassing, drain-back, mixing and assimilation are important processes at Kilauea Volcano. Volcanic gases have not illustrated these kinds of processes clearly in the past, owing to infrequent and poorly resolved data. New, detailed studies of volcanic gas emissions have refined our understanding of volatile degassing and magma budgets at Kilauea Volcano. Open Path Fourier Transform Infra-Red spectroscopy measurements carried out during 2004-2005 allow retrieval of the relative abundances of the major volatile species H2O, CO2 and SO2, which together make up >99 vol% of the magmatic vapor phase. The proportions of these gases vary over time and space and can be used to infer magma transport, ascent, degassing, overturn and mixing and gas segregation processes within the plumbing system of Kilauea Volcano. Gases from Pu`u `O`o in 2004-2005 display a range in composition. A trend relates molar C/S to the total H2O content of the gases over time and space; total H2O ranges from 60-98 mol %, while molar C/S ranges from <0.01 to >50. The range in volcanic gas composition over time and space is caused by magma degassing, overturn and mixing of partially degassed magma with fresh primary magma beneath Pu`u `O`o. Measurements of the mean rate of magma degassing (from SO2 emissions) and mean lava effusion rate (from geophysical measurements of lava tube flux) suggest that a larger volume (DRE) of magma is degassing than is being erupted, on average. This analysis suggests that magma storage in the Rift Zone might be important during eruptions as well as between them; this has important implications for volcano monitoring. Application of this new, remote and accurate technique to measure volcanic gases allows data concerning the volatile budget, both from glasses and from gases, to be reconciled and used in tandem to provide more detailed and complete models for magma migration, storage and transport at Kilauea Volcano.

Tomographic Location of Potential Melt-Bearing Phenocrysts in Lunar Glass Spherules

NASA Technical Reports Server (NTRS)

Ebel, D. S.; Fogel, R. A.; Rivers, M. L.

2005-01-01

In 1971, Apollo 17 astronauts collected a 10 cm soil sample (74220) comprised almost entirely of orange glass spherules. Below this, a double drive-tube core sampled a 68 cm thick horizon comprised of orange glass and black beads (crystallized equivalents of orange glass). Primitive lunar glass spherules (e.g.-A17 orange glasses) are thought to represent ejecta from lunar mare fire fountains [1, 2]. The fire-fountains were apparently driven by a combination of C-O gas ex-solution from orange glass melt and the oxidation of graphite [3, 4]. Upon eruption, magmas lost their volatiles (e.g., S, CO, CO2) to space. Evidence for volatile escape remains as volatile-rich coatings on the exteriors of many spherules [e.g., 5,6]. Moreover, [7] showed that Type I and II Fe-Ni-rich metal particles found within orange glass olivine phenocrysts, or free-floating in the glass itself, are powerful evidence for the volatile driving force for lunar fire fountains.

Ripening-dependent metabolic changes in the volatiles of pineapple (Ananas comosus (L.) Merr.) fruit: I. Characterization of pineapple aroma compounds by comprehensive two-dimensional gas chromatography-mass spectrometry.

PubMed

Steingass, Christof Björn; Carle, Reinhold; Schmarr, Hans-Georg

2015-03-01

Qualitative ripening-dependent changes of pineapple volatiles were studied via headspace solid-phase microextraction and analyzed by comprehensive two-dimensional gas chromatography quadrupole mass spectrometry (HS-SPME-GC×GC-qMS). Early green-ripe stage, post-harvest ripened, and green-ripe fruits at the end of their commercial shelf-life were compared to air-freighted pineapples harvested at full maturity. In total, more than 290 volatiles could be identified by mass spectrometry and their linear retention indices. The majority of compounds comprise esters (methyl and ethyl esters of saturated and unsaturated fatty acids, acetates), terpenes, alcohols, aldehydes, 2-ketones, free fatty acids, and miscellaneous γ- and δ-lactones. The structured separation space obtained by GC×GC allowed revealing various homologous series of compound classes as well as clustering of sesquiterpenes. Post-harvest ripening increased the diversity of the volatile profile compared to both early green-ripe maturity stages and on-plant ripened fruits.

Fault-tolerant NAND-flash memory module for next-generation scientific instruments

NASA Astrophysics Data System (ADS)

Lange, Tobias; Michel, Holger; Fiethe, Björn; Michalik, Harald; Walter, Dietmar

2015-10-01

Remote sensing instruments on today's space missions deliver a high amount of data which is typically evaluated on ground. Especially for deep space missions the telemetry downlink is very limited which creates the need for the scientific evaluation and thereby a reduction of data volume already on-board the spacecraft. A demanding example is the Polarimetric and Helioseismic Imager (PHI) instrument on Solar Orbiter. To enable on-board offline processing for data reduction, the instrument has to be equipped with a high capacity memory module. The module is based on non-volatile NAND-Flash technology, which requires more advanced operation than volatile DRAM. Unlike classical mass memories, the module is integrated into the instrument and allows readback of data for processing. The architecture and safe operation of such kind of memory module is described in the following paper.

Testing the Caustic Ring Dark Matter Halo Model Against Observations in the Milky Way

NASA Astrophysics Data System (ADS)

Dumas, Julie; Newberg, Heidi Jo; Niedzielski, Bethany; Susser, Adam; Thompson, Jeffery M.; Weiss, Jake; Lewis, Kim M.

2016-06-01

One prediction of axion dark matter models is they can form Bose-Einstein condensates and rigid caustic rings as a halo collapses in the non-linear regime. In this thesis, we undertake the first study of a caustic ring model for the Milky Way halo (Duffy & Sikivie 2008), paying particular attention to observational consequences. We first present the formalism for calculating the gravitational acceleration of a caustic ring halo. The caustic ring dark matter theory reproduces a roughly logarithmic halo, with large perturbations near the rings. We show that this halo can reasonably match the known Galactic rotation curve. We are not able to confirm or rule out an association between the positions of the caustic rings and oscillations in the observed rotation curve, due to insufficient rotation curve data. We explore the effects of dark matter caustic rings on dwarf galaxy tidal disruption with N-body simulations. Simulations of the Sagittarius (Sgr) dwarf galaxy in a caustic ring halo potential, with disk and bulge parameters that are tuned to match the Galactic rotation curve, match observations of the Sgr trailing tidal tails as far as 90 kpc from the Galactic center. Like the Navarro-Frenk-White (NFW) halo, they are, however, unable to match the leading tidal tail. None of the caustic, NFW, or triaxial logarithmic halos are able to simultaneously match observations of the leading and trailing arms of the Sagittarius stream. We further show that simulations of dwarf galaxies that move through caustic rings are qualitatively similar to those moving in a logarithmic halo. This research was funded by NSF grant AST 10-09670, the NASA-NY Space Grant, and the American Fellowship from AAUW.

Factorization and resummation for groomed multi-prong jet shapes

NASA Astrophysics Data System (ADS)

Larkoski, Andrew J.; Moult, Ian; Neill, Duff

2018-02-01

Observables which distinguish boosted topologies from QCD jets are playing an increasingly important role at the Large Hadron Collider (LHC). These observables are often used in conjunction with jet grooming algorithms, which reduce contamination from both theoretical and experimental sources. In this paper we derive factorization formulae for groomed multi-prong substructure observables, focusing in particular on the groomed D 2 observable, which is used to identify boosted hadronic decays of electroweak bosons at the LHC. Our factorization formulae allow systematically improvable calculations of the perturbative D 2 distribution and the resummation of logarithmically enhanced terms in all regions of phase space using renormalization group evolution. They include a novel factorization for the production of a soft subjet in the presence of a grooming algorithm, in which clustering effects enter directly into the hard matching. We use these factorization formulae to draw robust conclusions of experimental relevance regarding the universality of the D 2 distribution in both e + e - and pp collisions. In particular, we show that the only process dependence is carried by the relative quark vs. gluon jet fraction in the sample, no non-global logarithms from event-wide correlations are present in the distribution, hadronization corrections are controlled by the perturbative mass of the jet, and all global color correlations are completely removed by grooming, making groomed D 2 a theoretically clean QCD observable even in the LHC environment. We compute all ingredients to one-loop accuracy, and present numerical results at next-to-leading logarithmic accuracy for e + e - collisions, comparing with parton shower Monte Carlo simulations. Results for pp collisions, as relevant for phenomenology at the LHC, are presented in a companion paper [1].

Q estimation of seismic data using the generalized S-transform

NASA Astrophysics Data System (ADS)

Hao, Yaju; Wen, Xiaotao; Zhang, Bo; He, Zhenhua; Zhang, Rui; Zhang, Jinming

2016-12-01

Quality factor, Q, is a parameter that characterizes the energy dissipation during seismic wave propagation. The reservoir pore is one of the main factors that affect the value of Q. Especially, when pore space is filled with oil or gas, the rock usually exhibits a relative low Q value. Such a low Q value has been used as a direct hydrocarbon indicator by many researchers. The conventional Q estimation method based on spectral ratio suffers from the problem of waveform tuning; hence, many researchers have introduced time-frequency analysis techniques to tackle this problem. Unfortunately, the window functions adopted in time-frequency analysis algorithms such as continuous wavelet transform (CWT) and S-transform (ST) contaminate the amplitude spectra because the seismic signal is multiplied by the window functions during time-frequency decomposition. The basic assumption of the spectral ratio method is that there is a linear relationship between natural logarithmic spectral ratio and frequency. However, this assumption does not hold if we take the influence of window functions into consideration. In this paper, we first employ a recently developed two-parameter generalized S-transform (GST) to obtain the time-frequency spectra of seismic traces. We then deduce the non-linear relationship between natural logarithmic spectral ratio and frequency. Finally, we obtain a linear relationship between natural logarithmic spectral ratio and a newly defined parameter γ by ignoring the negligible second order term. The gradient of this linear relationship is 1/Q. Here, the parameter γ is a function of frequency and source wavelet. Numerical examples for VSP and post-stack reflection data confirm that our algorithm is capable of yielding accurate results. The Q-value results estimated from field data acquired in western China show reasonable comparison with oil-producing well location.

Quasi Sturmian basis for the two-electon continuum

NASA Astrophysics Data System (ADS)

Zaytsev, A. S.; Ancarani, L. U.; Zaytsev, S. A.

2016-02-01

A new type of basis functions is proposed to describe a two-electron continuum which arises as a final state in electron-impact ionization and double photoionization of atomic systems. We name these functions, which are calculated in terms of the recently introduced quasi Sturmian functions, Convoluted Quasi Sturmian functions (CQS); by construction, they look asymptotically like a six-dimensional spherical wave. The driven equation describing an ( e, 3 e) process on helium in the framework of the Temkin-Poet model is solved numerically in the entire space (rather than in a finite region of space) using expansions on CQS basis functions. We show that quite rapid convergence of the solution expansion can be achieved by multiplying the basis functions by the logarithmic phase factor corresponding to the Coulomb electron-electron interaction.

The First Deep Space Cubesat Broadband IR Spectrometer, Lunarcubes, and the Search for Lunar Volatiles

NASA Technical Reports Server (NTRS)

Clark, P. E.; Malphrus, Ben; Reuter, Dennis; MacDowall, Robert; Folta, David; Hurford, Terry; Brambora, Cliff; Farrell, William

2017-01-01

BIRCHES is the compact broadband IR spectrometer of the Lunar Ice Cube mission. Lunar Ice Cube is one of 13 6U cubesats that will be deployed by EM1 in cislunar space, qualifying as lunarcubes. The LunarCube paradigm is a proposed approach for extending the affordable CubeSat standard to support access to deep space via cis-lunar/lunar missions. Because the lunar environment contains analogs of most solar system environments, the Moon is an ideal target for both testing critical deep space capabilities and understanding solar system formation and processes. Effectively, as developments are occurring in parallel, 13 prototype deep space cubesats are being flown for EM1. One useful outcome of this 'experiment' will be to determine to what extent it is possible to develop a lunarcube 'bus' with standardized interfaces to all subsystems using reasonable protocols for a variety of payloads. The lunar ice cube mission was developed as the test case in a GSFC R&D study to determine whether the cubesat paradigm could be applied to deep space, science requirements driven missions, and BIRCHES was its payload. JPL's Lunar Flashlight, and Arizona State University's LunaH-Map, both also EM1 lunar orbiters, will also be deployed from EM1 and provide complimentary observations to be used in understanding volatile dynamics in the same time frame.

Hollows on Mercury: MESSENGER evidence for geologically recent volatile-related activity.

PubMed

Blewett, David T; Chabot, Nancy L; Denevi, Brett W; Ernst, Carolyn M; Head, James W; Izenberg, Noam R; Murchie, Scott L; Solomon, Sean C; Nittler, Larry R; McCoy, Timothy J; Xiao, Zhiyong; Baker, David M H; Fassett, Caleb I; Braden, Sarah E; Oberst, Jürgen; Scholten, Frank; Preusker, Frank; Hurwitz, Debra M

2011-09-30

High-resolution images of Mercury's surface from orbit reveal that many bright deposits within impact craters exhibit fresh-appearing, irregular, shallow, rimless depressions. The depressions, or hollows, range from tens of meters to a few kilometers across, and many have high-reflectance interiors and halos. The host rocks, which are associated with crater central peaks, peak rings, floors, and walls, are interpreted to have been excavated from depth by the crater-forming process. The most likely formation mechanisms for the hollows involve recent loss of volatiles through some combination of sublimation, space weathering, outgassing, or pyroclastic volcanism. These features support the inference that Mercury's interior contains higher abundances of volatile materials than predicted by most scenarios for the formation of the solar system's innermost planet.

Bio-Inspired Microsystem for Robust Genetic Assay Recognition

PubMed Central

Lue, Jaw-Chyng; Fang, Wai-Chi

2008-01-01

A compact integrated system-on-chip (SoC) architecture solution for robust, real-time, and on-site genetic analysis has been proposed. This microsystem solution is noise-tolerable and suitable for analyzing the weak fluorescence patterns from a PCR prepared dual-labeled DNA microchip assay. In the architecture, a preceding VLSI differential logarithm microchip is designed for effectively computing the logarithm of the normalized input fluorescence signals. A posterior VLSI artificial neural network (ANN) processor chip is used for analyzing the processed signals from the differential logarithm stage. A single-channel logarithmic circuit was fabricated and characterized. A prototype ANN chip with unsupervised winner-take-all (WTA) function was designed, fabricated, and tested. An ANN learning algorithm using a novel sigmoid-logarithmic transfer function based on the supervised backpropagation (BP) algorithm is proposed for robustly recognizing low-intensity patterns. Our results show that the trained new ANN can recognize low-fluorescence patterns better than an ANN using the conventional sigmoid function. PMID:18566679

A study of the eigenvectors of low frequency vibrational modes in crystalline cytidine via high pressure Raman spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Scott A.

2014-03-01

High-pressure Raman spectroscopy has been used to study the eigenvectors and eigenvalues of the low-frequency vibrational modes of crystalline cytidine at 295 K by evaluating the logarithmic derivative of the vibrational frequency with respect to pressure: 1/ω dω/dP. Crystalline samples of molecular materials such as cytidine have vibrational modes that are localized within a molecular unit (``internal'' modes) as well as modes in which the molecular units vibrate against each other (``external'' modes). The value of the logarithmic derivative is a diagnostic probe of the nature of the eigenvector of the vibrational modes, making high pressure experiments a very useful probe for such studies. Internal stretching modes have low logarithmic derivatives while external as well as internal torsional and bending modes have higher logarithmic derivatives. All of the Raman modes below 200 cm-1 in cytidine are found to have high logarithmic derivatives, consistent with being either external modes or internal torsional or bending modes.

Electronic filters, signal conversion apparatus, hearing aids and methods

NASA Technical Reports Server (NTRS)

Morley, Jr., Robert E. (Inventor); Engebretson, A. Maynard (Inventor); Engel, George L. (Inventor); Sullivan, Thomas J. (Inventor)

1994-01-01

An electronic filter for filtering an electrical signal. Signal processing circuitry therein includes a logarithmic filter having a series of filter stages with inputs and outputs in cascade and respective circuits associated with the filter stages for storing electrical representations of filter parameters. The filter stages include circuits for respectively adding the electrical representations of the filter parameters to the electrical signal to be filtered thereby producing a set of filter sum signals. At least one of the filter stages includes circuitry for producing a filter signal in substantially logarithmic form at its output by combining a filter sum signal for that filter stage with a signal from an output of another filter stage. The signal processing circuitry produces an intermediate output signal, and a multiplexer connected to the signal processing circuit multiplexes the intermediate output signal with the electrical signal to be filtered so that the logarithmic filter operates as both a logarithmic prefilter and a logarithmic postfilter. Other electronic filters, signal conversion apparatus, electroacoustic systems, hearing aids and methods are also disclosed.

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

Kolodrubetz, Daniel W.; Pietrulewicz, Piotr; Stewart, Iain W.

To predict the jet mass spectrum at a hadron collider it is crucial to account for the resummation of logarithms between the transverse momentum of the jet and its invariant mass m J . For small jet areas there are additional large logarithms of the jet radius R, which affect the convergence of the perturbative series. We present an analytic framework for exclusive jet production at the LHC which gives a complete description of the jet mass spectrum including realistic jet algorithms and jet vetoes. It factorizes the scales associated with m J , R, and the jet veto, enablingmore » in addition the systematic resummation of jet radius logarithms in the jet mass spectrum beyond leading logarithmic order. We discuss the factorization formulae for the peak and tail region of the jet mass spectrum and for small and large R, and the relations between the different regimes and how to combine them. Regions of experimental interest are classified which do not involve large nonglobal logarithms. We also present universal results for nonperturbative effects and discuss various jet vetoes.« less

A non-local structural derivative model for characterization of ultraslow diffusion in dense colloids

NASA Astrophysics Data System (ADS)

Liang, Yingjie; Chen, Wen

2018-03-01

Ultraslow diffusion has been observed in numerous complicated systems. Its mean squared displacement (MSD) is not a power law function of time, but instead a logarithmic function, and in some cases grows even more slowly than the logarithmic rate. The distributed-order fractional diffusion equation model simply does not work for the general ultraslow diffusion. Recent study has used the local structural derivative to describe ultraslow diffusion dynamics by using the inverse Mittag-Leffler function as the structural function, in which the MSD is a function of inverse Mittag-Leffler function. In this study, a new stretched logarithmic diffusion law and its underlying non-local structural derivative diffusion model are proposed to characterize the ultraslow diffusion in aging dense colloidal glass at both the short and long waiting times. It is observed that the aging dynamics of dense colloids is a class of the stretched logarithmic ultraslow diffusion processes. Compared with the power, the logarithmic, and the inverse Mittag-Leffler diffusion laws, the stretched logarithmic diffusion law has better precision in fitting the MSD of the colloidal particles at high densities. The corresponding non-local structural derivative diffusion equation manifests clear physical mechanism, and its structural function is equivalent to the first-order derivative of the MSD.

Quantitative relations between risk, return and firm size

NASA Astrophysics Data System (ADS)

Podobnik, B.; Horvatic, D.; Petersen, A. M.; Stanley, H. E.

2009-03-01

We analyze —for a large set of stocks comprising four financial indices— the annual logarithmic growth rate R and the firm size, quantified by the market capitalization MC. For the Nasdaq Composite and the New York Stock Exchange Composite we find that the probability density functions of growth rates are Laplace ones in the broad central region, where the standard deviation σ(R), as a measure of risk, decreases with the MC as a power law σ(R)~(MC)- β. For both the Nasdaq Composite and the S&P 500, we find that the average growth rate langRrang decreases faster than σ(R) with MC, implying that the return-to-risk ratio langRrang/σ(R) also decreases with MC. For the S&P 500, langRrang and langRrang/σ(R) also follow power laws. For a 20-year time horizon, for the Nasdaq Composite we find that σ(R) vs. MC exhibits a functional form called a volatility smile, while for the NYSE Composite, we find power law stability between σ(r) and MC.

Effectiveness of water-air and octanol-air partition coefficients to predict lipophilic flavor release behavior from O/W emulsions.

PubMed

Tamaru, Shunji; Igura, Noriyuki; Shimoda, Mitsuya

2018-01-15

Flavor release from food matrices depends on the partition of volatile flavor compounds between the food matrix and the vapor phase. Thus, we herein investigated the relationship between released flavor concentrations and three different partition coefficients, namely octanol-water, octanol-air, and water-air, which represented the oil, water, and air phases present in emulsions. Limonene, 2-methylpyrazine, nonanal, benzaldehyde, ethyl benzoate, α-terpineol, benzyl alcohol, and octanoic acid were employed. The released concentrations of these flavor compounds from oil-in-water (O/W) emulsions were measured under equilibrium using static headspace gas chromatography. The results indicated that water-air and octanol-air partition coefficients correlated with the logarithms of the released concentrations in the headspace for highly lipophilic flavor compounds. Moreover, the same tendency was observed over various oil volume ratios in the emulsions. Our findings therefore suggest that octanol-air and water-air partition coefficients can be used to predict the released concentration of lipophilic flavor compounds from O/W emulsions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulated space weathering of Fe- and Mg-rich aqueously altered minerals using pulsed laser irradiation

NASA Astrophysics Data System (ADS)

Kaluna, H. M.; Ishii, H. A.; Bradley, J. P.; Gillis-Davis, J. J.; Lucey, P. G.

2017-08-01

Simulated space weathering experiments on volatile-rich carbonaceous chondrites (CCs) have resulted in contrasting spectral behaviors (e.g. reddening vs bluing). The aim of this work is to investigate the origin of these contrasting trends by simulating space weathering on a subset of minerals found in these meteorites. We use pulsed laser irradiation to simulate micrometeorite impacts on aqueously altered minerals and observe their spectral and physical evolution as a function of irradiation time. Irradiation of the mineral lizardite, a Mg-phyllosilicate, produces a small degree of reddening and darkening, but a pronounced reduction in band depths with increasing irradiation. In comparison, irradiation of an Fe-rich aqueously altered mineral assemblage composed of cronstedtite, pyrite and siderite, produces significant darkening and band depth suppression. The spectral slopes of the Fe-rich assemblage initially redden then become bluer with increasing irradiation time. Post-irradiation analyses of the Fe-rich assemblage using scanning and transmission electron microscopy reveal the presence of micron sized carbon-rich particles that contain notable fractions of nitrogen and oxygen. Radiative transfer modeling of the Fe-rich assemblage suggests that nanometer sized metallic iron (npFe0) particles result in the initial spectral reddening of the samples, but the increasing production of micron sized carbon particles (μpC) results in the subsequent spectral bluing. The presence of npFe0 and the possible catalytic nature of cronstedtite, an Fe-rich phyllosilicate, likely promotes the synthesis of these carbon-rich, organic-like compounds. These experiments indicate that space weathering processes may enable organic synthesis reactions on the surfaces of volatile-rich asteroids. Furthermore, Mg-rich and Fe-rich aqueously altered minerals are dominant at different phases of the aqueous alteration process. Thus, the contrasting spectral slope evolution between the Fe- and Mg-rich samples in these experiments may indicate that space weathering trends of volatile-rich asteroids have a compositional dependency that could be used to determine the aqueous histories of asteroid parent bodies.

The Effect of Golden Pothos in Reducing the Level of Volatile Organic Compounds in a Simulated Spacecraft Cabin

NASA Technical Reports Server (NTRS)

Ursprung, Matthew; Amiri, Azita; Kayatin, Matthew; Perry, Jay

2016-01-01

The impact of Golden Pothos on indoor air quality was studied against a simulated spacecraft trace contaminant load model, consistent with the International Space Station (ISS), containing volatile organic compounds (VOCs) and formaldehyde. Previous research provides inconclusive results on the efficacy of plant VOC removal which this projects seeks to rectify through a better experimental design. This work develops a passive system for removing common VOC's from spacecraft and household indoor air and decreasing the necessity for active cabin trace contaminant removal systems.

The effect of sensor spacing on wind measurements at the Shuttle Landing Facility

NASA Technical Reports Server (NTRS)

Merceret, Francis J.

1995-01-01

This document presents results of a field study of the effect of sensor spacing on the validity of wind measurements at the Space Shuttle landing Facility (SLF). Standard measurements are made at one second intervals from 30 foot (9.1m) towers located 500 feet (152m) from the SLF centerline. The centerline winds are not exactly the same as those measured by the towers. This study quantifies the differences as a function of statistics of the observed winds and distance between the measurements and points of interest. The field program used logarithmically spaced portable wind towers to measure wind speed and direction over a range of conditions. Correlations, spectra, moments, and structure functions were computed. A universal normalization for structure functions was devised. The normalized structure functions increase as the 2/3 power of separation distance until an asymptotic value is approached. This occurs at spacings of several hundred feet (about 100m). At larger spacings, the structure functions are bounded by the asymptote. This enables quantitative estimates of the expected differences between the winds at the measurement point and the points of interest to be made from the measured wind statistics. A procedure is provided for making these estimates.

Analog synthetic biology.

PubMed

Sarpeshkar, R

2014-03-28

We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog-digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA-protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations.

Analog synthetic biology

PubMed Central

Sarpeshkar, R.

2014-01-01

We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog–digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA–protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

A new real-time guidance strategy for aerodynamic ascent flight

NASA Astrophysics Data System (ADS)

Yamamoto, Takayuki; Kawaguchi, Jun'ichiro

2007-12-01

Reusable launch vehicles are conceived to constitute the future space transportation system. If these vehicles use air-breathing propulsion and lift taking-off horizontally, the optimal steering for these vehicles exhibits completely different behavior from that in conventional rockets flight. In this paper, the new guidance strategy is proposed. This method derives from the optimality condition as for steering and an analysis concludes that the steering function takes the form comprised of Linear and Logarithmic terms, which include only four parameters. The parameter optimization of this method shows the acquired terminal horizontal velocity is almost same with that obtained by the direct numerical optimization. This supports the parameterized Liner Logarithmic steering law. And here is shown that there exists a simple linear relation between the terminal states and the parameters to be corrected. The relation easily makes the parameters determined to satisfy the terminal boundary conditions in real-time. The paper presents the guidance results for the practical application cases. The results show the guidance is well performed and satisfies the terminal boundary conditions specified. The strategy built and presented here does guarantee the robust solution in real-time excluding any optimization process, and it is found quite practical.

Spinning solutions in general relativity with infinite central density

NASA Astrophysics Data System (ADS)

Flammer, P. D.

2018-05-01

This paper presents general relativistic numerical simulations of uniformly rotating polytropes. Equations are developed using MSQI coordinates, but taking a logarithm of the radial coordinate. The result is relatively simple elliptical differential equations. Due to the logarithmic scale, we can resolve solutions with near-singular mass distributions near their center, while the solution domain extends many orders of magnitude larger than the radius of the distribution (to connect with flat space-time). Rotating solutions are found with very high central energy densities for a range of adiabatic exponents. Analytically, assuming the pressure is proportional to the energy density (which is true for polytropes in the limit of large energy density), we determine the small radius behavior of the metric potentials and energy density. This small radius behavior agrees well with the small radius behavior of large central density numerical results, lending confidence to our numerical approach. We compare results with rotating solutions available in the literature, which show good agreement. We study the stability of spherical solutions: instability sets in at the first maximum in mass versus central energy density; this is also consistent with results in the literature, and further lends confidence to the numerical approach.

Impact of VOC removal by activated carbon on biodegradation rates of diesel, Syntroleum and biodiesel in contaminated sand.

PubMed

Horel, Agota; Schiewer, Silke

2016-12-15

The degradation of conventional diesel (D), synthetic diesel (Syntroleum), and pure fish biodiesel (B100) by indigenous microbes was investigated in laboratory microcosms containing contaminated sand. The fate of volatiles and the influence of volatilization on degradation rates were examined by placing activated carbon (AC) in microcosm headspaces to sorb volatiles. Three AC regimes were compared: no activated carbon (NAC), regular weekly AC change (RAC), and frequent AC change (FAC), where the frequency of activated carbon exchange declined from daily to weekly. Generally, the alternative fuels were biodegraded faster than diesel fuel. Hydrocarbon mineralization percentages for the different fuel types over 28days were between 23% (D) and 48% (B100) in the absence of activated carbon, decreased to 12% (D) - 37% (B100) with weekly AC exchange, and were further reduced to 9-22% for more frequent AC change. Sorption of volatiles to AC lowered their availability as a substrate for microbes, reducing respiration. Volatilization was negligible for the biodiesel. A mass balance for the carbon initially present as hydrocarbons in microcosms with activated carbon in the head space was on average 92% closed, with 45-70% remaining in the soil after 4weeks, 9-37% mineralized and up to 12% volatilized. Based on nutrient consumption, up to 29% of the contaminants were likely converted into biomass. Copyright © 2016 Elsevier B.V. All rights reserved.

On the Use of the Log-Normal Particle Size Distribution to Characterize Global Rain

NASA Technical Reports Server (NTRS)

Meneghini, Robert; Rincon, Rafael; Liao, Liang

2003-01-01

Although most parameterizations of the drop size distributions (DSD) use the gamma function, there are several advantages to the log-normal form, particularly if we want to characterize the large scale space-time variability of the DSD and rain rate. The advantages of the distribution are twofold: the logarithm of any moment can be expressed as a linear combination of the individual parameters of the distribution; the parameters of the distribution are approximately normally distributed. Since all radar and rainfall-related parameters can be written approximately as a moment of the DSD, the first property allows us to express the logarithm of any radar/rainfall variable as a linear combination of the individual DSD parameters. Another consequence is that any power law relationship between rain rate, reflectivity factor, specific attenuation or water content can be expressed in terms of the covariance matrix of the DSD parameters. The joint-normal property of the DSD parameters has applications to the description of the space-time variation of rainfall in the sense that any radar-rainfall quantity can be specified by the covariance matrix associated with the DSD parameters at two arbitrary space-time points. As such, the parameterization provides a means by which we can use the spaceborne radar-derived DSD parameters to specify in part the covariance matrices globally. However, since satellite observations have coarse temporal sampling, the specification of the temporal covariance must be derived from ancillary measurements and models. Work is presently underway to determine whether the use of instantaneous rain rate data from the TRMM Precipitation Radar can provide good estimates of the spatial correlation in rain rate from data collected in 5(sup 0)x 5(sup 0) x 1 month space-time boxes. To characterize the temporal characteristics of the DSD parameters, disdrometer data are being used from the Wallops Flight Facility site where as many as 4 disdrometers have been used to acquire data over a 2 km path. These data should help quantify the temporal form of the covariance matrix at this site.

Partitioning of F and Cl Between Apatite and a Synthetic Shergottite Liquid (QUE 94201) at 4 Gpa from 1300 TO 1500 C

NASA Technical Reports Server (NTRS)

McCubbin, F. M.; Barnes, J. J.; Vander Kaaden, K. E.; Boyce, J. W.

2017-01-01

Apatite [Ca5(PO4)3(F,Cl,OH)] is present in a wide range of planetary materials. Due to the presence of volatiles within its crystal structure (Xsite), many recent studies have attempted to use apatite to constrain the volatile contents of planetary magmas and mantle sources. In order to use the volatile contents of apatite to accurately determine the abundances of volatiles in coexisting silicate melt or fluids, thermodynamic models for the apatite solid solution and for the apatite components in multicomponent silicate melts and fluids are required. Although some thermodynamic models for apatite have been developed, they are incomplete. Furthermore, no mixing model is available for all of the apatite components in silicate melts or fluids, especially for F and Cl components. Several experimental studies have investigated the apatite-melt and apatite-fluid partitioning behavior of F, Cl, and OH in terrestrial and planetary systems, which have determined that apatite-melt partitioning of volatiles are best described as exchange equilibria similar to Fe-Mg partitioning between olivine and silicate melt. However, McCubbin et al., recently reported that the exchange coefficients vary in portions of apatite compositional space where F, Cl, and OH do not mix ideally in apatite. In particular, solution calorimetry data of apatite compositions along the F-Cl join exhibit substantial excess enthalpies of mixing, and McCubbin et al. reported substantial deviations in the Cl-F exchange Kd along the F-Cl apatite join that could be explained by the preferential incorporation of F into apatite. In the present study, we assess the effect of apatite crystal chemistry on F-Cl exchange equilibria between apatite and melt at 4 GPa over the temperature range of 1300-1500 C. The goal of these experiments is to assess the variation in the Ap-melt Cl-F exchange Kd over a broad range of F:Cl ratios in apatite. The results of these experiments could be used to understand at what composition apatite shifts from a hexagonal unit cell with space group P63/m to a unit cell with monoclinic symmetry within space group P21/b. We anticipate that this transition occurs at >70% chlorapatite based on solution calorimetry data.

Lunar volatiles: balancing science and resource development

NASA Astrophysics Data System (ADS)

Crider, Dana

In the context of human exploration of the moon, the volatiles postulated to exist at the lunar poles have value as resources as well as scientific significance. Once sustained human operations commence on the moon, society will move from a paradigm in which examination of planetary materials has been unconstrained to one where use of those materials will support habitability and further exploration. A framework for the scientific investigation of lunar volatiles that allows for eventual economic exploitation can guide both activities and resolve the conflicts that will inevitably develop if the postulated lunar volatiles prove to be both extant and accessible. Scientific constraints on the framework include characterization at both poles of the isotopes, elements, and molecules in the volatiles, their relative and absolute abundances, and their horizontal and vertical distribution. A subset of this data is necessary in order to assess, develop, and initiate resource exploitation. In addition, the scientific record of volatiles in the cold traps can be contaminated by the cold-trapping of migrating volatiles released from operations elsewhere on the moon even if the indigenous, cold-trapped volatiles are not utilized. Possible decision points defining the transition from science-dominated to exploitation-dominated use include technology limits in the 70K environment, evolving science priorities (funding), and the resolution of major science issues. Inputs to policy development include any North vs. South Pole differences in volatile characteristics and the suitability of the volatiles to enable further scientific exploration of the moon. In the absence of national sovereignty on the moon, enforcement of any framework is an open question, particularly if science and commercial interests are in competition. The framework, processes, and precedent set by how we as a society choose to handle the scientific bounty and resource promise of lunar volatiles may eventually apply to Mars and near-earth asteroids. We believe there are useful lessons to be learned from the terrestrial experience with protected areas such as national parks, wilderness areas, and archeological sites. International agreements such as the Antarctic Treaty (in force since 1961), the Outer Space Treaty (1967), and the Moon Treaty (1979) carry relevant lessons as well.

Small range logarithm calculation on Intel Quartus II Verilog

NASA Astrophysics Data System (ADS)

Mustapha, Muhazam; Mokhtar, Anis Shahida; Ahmad, Azfar Asyrafie

2018-02-01

Logarithm function is the inverse of exponential function. This paper implement power series of natural logarithm function using Verilog HDL in Quartus II. The mode of design used is RTL in order to decrease the number of megafunctions. The simulations were done to determine the precision and number of LEs used so that the output calculated accurately. It is found that the accuracy of the system only valid for the range of 1 to e.

The lead isotopic age of the Earth can be explained by core formation alone.

PubMed

Wood, Bernard J; Halliday, Alex N

2010-06-10

The meaning of the age of the Earth defined by lead isotopes has long been unclear. Recently it has been proposed that the age of the Earth deduced from lead isotopes reflects volatile loss to space at the time of the Moon-forming giant impact rather than partitioning into metallic liquids during protracted core formation. Here we show that lead partitioning into liquid iron depends strongly on carbon content and that, given a content of approximately 0.2% carbon, experimental and isotopic data both provide evidence of strong partitioning of lead into the core throughout the Earth's accretion. Earlier conclusions that lead is weakly partitioned into iron arose from the use of carbon-saturated (about 5% C) iron alloys. The lead isotopic age of the Earth is therefore consistent with partitioning into the core and with no significant late losses of moderately volatile elements to space during the giant impact.

VOLATILE-RICH CIRCUMSTELLAR GAS IN THE UNUSUAL 49 CETI DEBRIS DISK

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

Roberge, Aki; Grady, Carol A.; Welsh, Barry Y.

2014-11-20

We present Hubble Space Telescope Space Telescope Imaging Spectrograph far-UV spectra of the edge-on disk around 49 Ceti, one of the very few debris disks showing submillimeter CO emission. Many atomic absorption lines are present in the spectra, most of which arise from circumstellar gas lying along the line-of-sight to the central star. We determined the line-of-sight C I column density, estimated the total carbon column density, and set limits on the O I column density. Surprisingly, no line-of-sight CO absorption was seen. We discuss possible explanations for this non-detection, and present preliminary estimates of the carbon abundances in themore » line-of-sight gas. The C/Fe ratio is much greater than the solar value, suggesting that 49 Cet harbors a volatile-rich gas disk similar to that of β Pictoris.« less

ASTROCULTURE(tm) Commercial Plant Growth Unit and Glove Box Insert

NASA Technical Reports Server (NTRS)

Zhou, Wei-Jia; Lambing, Steve (Technical Monitor)

2002-01-01

Two commercial plant investigations will be conducted during the STS-107 mission: living flower essential oil production and gene transfer. The research will be done using the ASTROCULTURE (trademark) hardware, which builds on similar experiments flown in the past on the space shuttle. This research will investigate how microgravity might affect the formation of the volatile chemical compounds - the essential oils - produced by two different types of living flowers. The flowers will be cultured in the ASTROCULTURE (trademark) plant chamber, which provides an enclosed and controlled environment. As the flowers bloom in space, they will produce essential oils, and these volatile compounds will be collected using International Flavors and Fragrance's proprietary Solid Phase Micro Extraction (SPME) technology. The gene transfer experiment examines a newly developed transformation system to see if it operates efficiently in the microgravity environment. This research is important for the development of genetically engineered crops, also known as transgenic crops.

Study of the aroma formation and transformation during the manufacturing process of oolong tea by solid-phase micro-extraction and gas chromatography-mass spectrometry combined with chemometrics.

PubMed

Ma, Chengying; Li, Junxing; Chen, Wei; Wang, Wenwen; Qi, Dandan; Pang, Shi; Miao, Aiqing

2018-06-01

Oolong tea is a typical semi-fermented tea and is famous for its unique aroma. The aim of this study was to compare the volatile compounds during manufacturing process to reveal the formation of aroma. In this paper, a method was developed based on head-space solid phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC-MS) combined with chemometrics to assess volatile profiles during manufacturing process (fresh leaves, sun-withered leaves, rocked leaves and leaves after de-enzyming). A total of 24 aroma compounds showing significant differences during manufacturing process were identified. Subsequently, according to these aroma compounds, principal component analysis and hierarchical cluster analysis showed that the four samples were clearly distinguished from each other, which suggested that the 24 identified volatile compounds can represent the changes of volatile compounds during the four steps. Additionally, sun-withering, rocking and de-enzyming can influence the variations of volatile compounds in different degree, and we found the changes of volatile compounds in withering step were less than other two manufacturing process, indicating that the characteristic volatile compounds of oolong tea might be mainly formed in rocking stage by biological reactions and de-enzyming stage through thermal chemical transformations rather than withering stage. This study suggested that HS-SPME/GC-MS combined with chemometrics methods is accurate, sensitive, fast and ideal for rapid routine analysis of the aroma compounds changes in oolong teas during manufacturing processing. Copyright © 2018 Elsevier Ltd. All rights reserved.

Continuous time random walk model with asymptotical probability density of waiting times via inverse Mittag-Leffler function

NASA Astrophysics Data System (ADS)

Liang, Yingjie; Chen, Wen

2018-04-01

The mean squared displacement (MSD) of the traditional ultraslow diffusion is a logarithmic function of time. Recently, the continuous time random walk model is employed to characterize this ultraslow diffusion dynamics by connecting the heavy-tailed logarithmic function and its variation as the asymptotical waiting time density. In this study we investigate the limiting waiting time density of a general ultraslow diffusion model via the inverse Mittag-Leffler function, whose special case includes the traditional logarithmic ultraslow diffusion model. The MSD of the general ultraslow diffusion model is analytically derived as an inverse Mittag-Leffler function, and is observed to increase even more slowly than that of the logarithmic function model. The occurrence of very long waiting time in the case of the inverse Mittag-Leffler function has the largest probability compared with the power law model and the logarithmic function model. The Monte Carlo simulations of one dimensional sample path of a single particle are also performed. The results show that the inverse Mittag-Leffler waiting time density is effective in depicting the general ultraslow random motion.

Logarithmic spiral trajectories generated by Solar sails

NASA Astrophysics Data System (ADS)

Bassetto, Marco; Niccolai, Lorenzo; Quarta, Alessandro A.; Mengali, Giovanni

2018-02-01

Analytic solutions to continuous thrust-propelled trajectories are available in a few cases only. An interesting case is offered by the logarithmic spiral, that is, a trajectory characterized by a constant flight path angle and a fixed thrust vector direction in an orbital reference frame. The logarithmic spiral is important from a practical point of view, because it may be passively maintained by a Solar sail-based spacecraft. The aim of this paper is to provide a systematic study concerning the possibility of inserting a Solar sail-based spacecraft into a heliocentric logarithmic spiral trajectory without using any impulsive maneuver. The required conditions to be met by the sail in terms of attitude angle, propulsive performance, parking orbit characteristics, and initial position are thoroughly investigated. The closed-form variations of the osculating orbital parameters are analyzed, and the obtained analytical results are used for investigating the phasing maneuver of a Solar sail along an elliptic heliocentric orbit. In this mission scenario, the phasing orbit is composed of two symmetric logarithmic spiral trajectories connected with a coasting arc.

Optimization of non-linear gradient in hydrophobic interaction chromatography for the analytical characterization of antibody-drug conjugates.

PubMed

Bobály, Balázs; Randazzo, Giuseppe Marco; Rudaz, Serge; Guillarme, Davy; Fekete, Szabolcs

2017-01-20

The goal of this work was to evaluate the potential of non-linear gradients in hydrophobic interaction chromatography (HIC), to improve the separation between the different homologous species (drug-to-antibody, DAR) of commercial antibody-drug conjugates (ADC). The selectivities between Brentuximab Vedotin species were measured using three different gradient profiles, namely linear, power function based and logarithmic ones. The logarithmic gradient provides the most equidistant retention distribution for the DAR species and offers the best overall separation of cysteine linked ADC in HIC. Another important advantage of the logarithmic gradient, is its peak focusing effect for the DAR0 species, which is particularly useful to improve the quantitation limit of DAR0. Finally, the logarithmic behavior of DAR species of ADC in HIC was modelled using two different approaches, based on i) the linear solvent strength theory (LSS) and two scouting linear gradients and ii) a new derived equation and two logarithmic scouting gradients. In both cases, the retention predictions were excellent and systematically below 3% compared to the experimental values. Copyright © 2016 Elsevier B.V. All rights reserved.

Electronic filters, repeated signal charge conversion apparatus, hearing aids and methods

NASA Technical Reports Server (NTRS)

Morley, Jr., Robert E. (Inventor); Engebretson, A. Maynard (Inventor); Engel, George L. (Inventor); Sullivan, Thomas J. (Inventor)

1993-01-01

An electronic filter for filtering an electrical signal. Signal processing circuitry therein includes a logarithmic filter having a series of filter stages with inputs and outputs in cascade and respective circuits associated with the filter stages for storing electrical representations of filter parameters. The filter stages include circuits for respectively adding the electrical representations of the filter parameters to the electrical signal to be filtered thereby producing a set of filter sum signals. At least one of the filter stages includes circuitry for producing a filter signal in substantially logarithmic form at its output by combining a filter sum signal for that filter stage with a signal from an output of another filter stage. The signal processing circuitry produces an intermediate output signal, and a multiplexer connected to the signal processing circuit multiplexes the intermediate output signal with the electrical signal to be filtered so that the logarithmic filter operates as both a logarithmic prefilter and a logarithmic postfilter. Other electronic filters, signal conversion apparatus, electroacoustic systems, hearing aids and methods are also disclosed.

Threshold and Jet Radius Joint Resummation for Single-Inclusive Jet Production

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

Liu, Xiaohui; Moch, Sven -Olaf; Ringer, Felix

Here, we present the first threshold and jet radius jointly resummed cross section for single-inclusive hadronic jet production. We work at next-to-leading logarithmic accuracy and our framework allows for a systematic extension beyond the currently achieved precision. Long-standing numerical issues are overcome by performing the resummation directly in momentum space within soft collinear effective theory. We present the first numerical results for the LHC and observe an improved description of the available data. Our results are of immediate relevance for LHC precision phenomenology including the extraction of parton distribution functions and the QCD strong coupling constant.

Orbital stability of periodic traveling-wave solutions for the log-KdV equation

NASA Astrophysics Data System (ADS)

Natali, Fábio; Pastor, Ademir; Cristófani, Fabrício

2017-09-01

In this paper we establish the orbital stability of periodic waves related to the logarithmic Korteweg-de Vries equation. Our motivation is inspired in the recent work [3], in which the authors established the well-posedness and the linear stability of Gaussian solitary waves. By using the approach put forward recently in [20] to construct a smooth branch of periodic waves as well as to get the spectral properties of the associated linearized operator, we apply the abstract theories in [13] and [25] to deduce the orbital stability of the periodic traveling waves in the energy space.

On the explicit construction of Parisi landscapes in finite dimensional Euclidean spaces

NASA Astrophysics Data System (ADS)

Fyodorov, Y. V.; Bouchaud, J.-P.

2007-12-01

An N-dimensional Gaussian landscape with multiscale translation-invariant logarithmic correlations has been constructed, and the statistical mechanics of a single particle in this environment has been investigated. In the limit of a high dimensional N → ∞, the free energy of the system in the thermodynamic limit coincides with the most general version of Derrida’s generalized random energy model. The low-temperature behavior depends essentially on the spectrum of length scales involved in the construction of the landscape. The construction is argued to be valid in any finite spatial dimensions N ≥1.

Image Science Research for Speckle-based LADAR (Speckle Research for 3D Imaging LADAR)

DTIC Science & Technology

2008-04-03

INVARIANT + FERGUS, TORRALBA, AND FREEMAN. MIT-CSAIL-TR-2006-058 MAP DETECTOR PATTERN FOR EACH POINT IN OBJECT SPACE DEBLURRING PROBLEM IMPULSE RESPONSE...GENERALIZED THEORY FOR THE LOGARITHMIC ASPHERE ( )( ) it e φ ρρ −= IMPULSE RESPONSE (PSF) 2 2 2 2 0 0 22 2( ) 2 2 0 2 2 2 2 2 2 0 0 2 ( ; ) 2 ( ) i s i i t R...ascent; γ=1, Burch, Skilling, Gull; Loops needed Noise deviation Area of PSF New parameter L σ A γ COMPARISON OF MAXIMUM ENTROPY METHODS † † W. CHI

Threshold and Jet Radius Joint Resummation for Single-Inclusive Jet Production

DOE PAGES

Liu, Xiaohui; Moch, Sven -Olaf; Ringer, Felix

2017-11-20

Here, we present the first threshold and jet radius jointly resummed cross section for single-inclusive hadronic jet production. We work at next-to-leading logarithmic accuracy and our framework allows for a systematic extension beyond the currently achieved precision. Long-standing numerical issues are overcome by performing the resummation directly in momentum space within soft collinear effective theory. We present the first numerical results for the LHC and observe an improved description of the available data. Our results are of immediate relevance for LHC precision phenomenology including the extraction of parton distribution functions and the QCD strong coupling constant.

Volatile organic compound measurements at Trinidad Head, California, during ITCT 2K2: Analysis of sources, atmospheric composition, and aerosol residence times

NASA Astrophysics Data System (ADS)

Millet, Dylan B.; Goldstein, Allen H.; Allan, James D.; Bates, Timothy S.; Boudries, Hacene; Bower, Keith N.; Coe, Hugh; Ma, Yilin; McKay, Megan; Quinn, Patricia K.; Sullivan, Amy; Weber, Rodney J.; Worsnop, Douglas R.

2004-12-01

We report hourly in-situ observations of C1-C8 speciated volatile organic compounds (VOCs) obtained at Trinidad Head CA in April and May 2002 as part of the NOAA Intercontinental Transport and Chemical Transformation study. Factor analysis of the VOC data set was used to define the dominant processes driving atmospheric chemical composition at the site, and to characterize the sources for measured species. Strong decreases in background concentration were observed for several of the VOCs during the experiment due to seasonal changes in OH concentration. CO was the most important contributor to the total measured OH reactivity at the site at all times. Oxygenated VOCs were the primary component of both the total VOC burden and of the VOC OH reactivity, and their relative importance was enhanced under conditions when local source contributions were minimal. VOC variability exhibited a strong dependence on residence time (slnX = 1.55τ-0.44, r2 = 0.98; where slnX is the standard deviation of the natural logarithm of the mixing ratio), and this relationship was used, in conjunction with measurements of 222Rn, to estimate the average OH concentration during the study period (6.1 × 105 molec/cm3). We also employed the variability-lifetime relationship defined by the VOC data set to estimate submicron aerosol residence times as a function of chemical composition. Two independent measures of aerosol chemical composition yielded consistent residence time estimates. Lifetimes calculated in this manner were between 3-7 days for aerosol nitrate, organics, sulfate, and ammonium. The lifetime estimate for methane sulfonic acid (˜12 days) was slightly outside of this range. The lifetime of the total aerosol number density was estimated at 9.8 days.

Impact of crema on the aroma release and the in-mouth sensory perception of espresso coffee.

PubMed

Barron, D; Pineau, N; Matthey-Doret, W; Ali, S; Sudre, J; Germain, J C; Kolodziejczyk, E; Pollien, P; Labbe, D; Jarisch, C; Dugas, V; Hartmann, C; Folmer, B

2012-09-01

A set of six espresso coffees with different foam characteristics and similar above cup and in-mouth flavour sensory profiles was produced by combination of two varying parameters, the extraction pressure and the filtration of the coffee beverage. The coffees were subsequently evaluated in a comparative manner by a set of analytical (headspace, nose-space) and sensory (Temporal Dominance of Sensations) techniques. The presence of espresso crema in its standard quantity was demonstrated to be associated with the optimum release of pleasant high volatiles, both in the above cup headspace and in-mouth. On the other hand, the TDS study demonstrated that increasing amount of crema was associated with increasing roasted dominance along coffee consumption. Furthermore, a parallel was established between the roasted sensory dominance and the dominant release of 2-methylfuran in the nose-space. This was, however, an indirect link as 2-methylfuran was indeed a chemical marker of roasting but does not contribute to the roasted aroma. Lowering the standard amount of crema by filtration clearly decreased the release of pleasant high volatiles and the in-mouth roasted sensory dominance. On the other hand, increasing the usual crema volume by increasing the extraction pressure did not bring any added value concerning the above cup and in-mouth release of pleasant high volatiles.

Extended Phase-Space Methods for Enhanced Sampling in Molecular Simulations: A Review.

PubMed

Fujisaki, Hiroshi; Moritsugu, Kei; Matsunaga, Yasuhiro; Morishita, Tetsuya; Maragliano, Luca

2015-01-01

Molecular Dynamics simulations are a powerful approach to study biomolecular conformational changes or protein-ligand, protein-protein, and protein-DNA/RNA interactions. Straightforward applications, however, are often hampered by incomplete sampling, since in a typical simulated trajectory the system will spend most of its time trapped by high energy barriers in restricted regions of the configuration space. Over the years, several techniques have been designed to overcome this problem and enhance space sampling. Here, we review a class of methods that rely on the idea of extending the set of dynamical variables of the system by adding extra ones associated to functions describing the process under study. In particular, we illustrate the Temperature Accelerated Molecular Dynamics (TAMD), Logarithmic Mean Force Dynamics (LogMFD), and Multiscale Enhanced Sampling (MSES) algorithms. We also discuss combinations with techniques for searching reaction paths. We show the advantages presented by this approach and how it allows to quickly sample important regions of the free-energy landscape via automatic exploration.

Transistor circuit increases range of logarithmic current amplifier

NASA Technical Reports Server (NTRS)

Gilmour, G.

1966-01-01

Circuit increases the range of a logarithmic current amplifier by combining a commercially available amplifier with a silicon epitaxial transistor. A temperature compensating network is provided for the transistor.

A class of reduced-order models in the theory of waves and stability.

PubMed

Chapman, C J; Sorokin, S V

2016-02-01

This paper presents a class of approximations to a type of wave field for which the dispersion relation is transcendental. The approximations have two defining characteristics: (i) they give the field shape exactly when the frequency and wavenumber lie on a grid of points in the (frequency, wavenumber) plane and (ii) the approximate dispersion relations are polynomials that pass exactly through points on this grid. Thus, the method is interpolatory in nature, but the interpolation takes place in (frequency, wavenumber) space, rather than in physical space. Full details are presented for a non-trivial example, that of antisymmetric elastic waves in a layer. The method is related to partial fraction expansions and barycentric representations of functions. An asymptotic analysis is presented, involving Stirling's approximation to the psi function, and a logarithmic correction to the polynomial dispersion relation.

Logarithmic corrections to black hole entropy from Kerr/CFT

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

Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew

It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Furthermore, Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. We compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

Logarithmic corrections to black hole entropy from Kerr/CFT

DOE PAGES

Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew; ...

2017-04-14

It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Furthermore, Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. We compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.

Integral definition of the logarithmic function and the derivative of the exponential function in calculus

NASA Astrophysics Data System (ADS)

Vaninsky, Alexander

2015-04-01

Defining the logarithmic function as a definite integral with a variable upper limit, an approach used by some popular calculus textbooks, is problematic. We discuss the disadvantages of such a definition and provide a way to fix the problem. We also consider a definition-based, rigorous derivation of the derivative of the exponential function that is easier, more intuitive, and complies with the standard definitions of the number e, the logarithmic, and the exponential functions.

Comets: Role and importance to exobiology

NASA Technical Reports Server (NTRS)

Delsemme, Armand H.

1992-01-01

The transfer of organic compounds from interstellar space to the outskirts of a protoplanetary disk, their accretion into cometary objects, and the transport of the latter into the inner solar system by orbital diffusion throw a new light on the central problem of exobiology. It suggests the existence of a cosmic mechanism, working everywhere, that can supply prebiotic compounds to ubiquitous rocky planets, in search of the proper environment to start life in many places in the Universe. Under the heading of chemistry of the cometary nucleus, the following topics are covered: radial homogeneity of the nucleus; the dust-to-ice ratio; nature of the dust grains; origin of the dust in comets; nature of the volatile fraction; the CO distribution in comet Halley; dust contribution to the volatile fraction; elemental balance sheet of comet Halley; quantitative molecular analysis of the volatile fraction; and isotopic ratios. Under the heading of exogenous origin of carbon on terrestrial planets the following topics are covered: evidence for a high-temperature phase; from planetesimals to planets; a veneer of volatile and organic material; and cometary contribution.

Odor and VOC Emissions from Pan Frying of Mackerel at Three Stages: Raw, Well-Done, and Charred

PubMed Central

Ahn, Jeong-Hyeon; Szulejko, Jan E.; Kim, Ki-Hyun; Kim, Yong-Hyun; Kim, Bo-Won

2014-01-01

Many classes of odorants and volatile organic compounds that are deleterious to our wellbeing can be emitted from diverse cooking activities. Once emitted, they can persist in our living space for varying durations. In this study, various volatile organic compounds released prior to and during the pan frying of fish (mackerel) were analyzed at three different cooking stages (stage 1 = raw (R), stage 2 = well-done (W), and stage 3 = overcooked/charred (O)). Generally, most volatile organic compounds recorded their highest concentration levels at stage 3 (O), e.g., 465 (trimethylamine) and 106 ppb (acetic acid). In contrast, at stage 2 (W), the lowest volatile organic compounds emissions were observed. The overall results of this study confirm that trimethylamine is identified as the strongest odorous compound, especially prior to cooking (stage 1 (R)) and during overcooking leading to charring (stage 3 (O)). As there is a paucity of research effort to measure odor intensities from pan frying of mackerel, this study will provide valuable information regarding the management of indoor air quality. PMID:25405596

Animal studies of life shortening and cancer risk from space radiation

NASA Astrophysics Data System (ADS)

Wood, D. H.; Yochmowitz, M. G.; Hardy, K. A.; Salmon, Y. L.

The U. S. Air Force study of the delayed effects of single, total body exposures to simulated space radiation in rhesus monkeys is now in its 21st year. Observations on 301 irradiated and 57 age-matched control animals indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be expressed as a logarithmic function of the dose. The primary causes of life shortening are cancer and endometriosis (an abnormal proliferation of the lining of the uterus in females). Life shortening estimates permit comparison of the risk associated with space radiation exposures to be compared with that of other occupational and environmental hazards, thereby facilitating risk/benefit decisions in the planning and operational phases of manned space missions. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of human is, therefore, critical to the assessment of life-time cancer risk.

Simulated real-time lunar volatiles prospecting with a rover-borne neutron spectrometer

NASA Astrophysics Data System (ADS)

Elphic, Richard C.; Heldmann, Jennifer L.; Marinova, Margarita M.; Colaprete, Anthony; Fritzler, Erin L.; McMurray, Robert E.; Morse, Stephanie; Roush, Ted L.; Stoker, Carol R.; Deans, Matthew C.; Smith, Trey F.

2015-05-01

In situ resource utilization (ISRU) may one day enable long duration lunar missions. But the efficacy of such an approach greatly depends on (1) physical and chemical makeup of the resource, and (2) the logistical cost of exploiting the resource. Establishing these key strategic factors requires prospecting: the capability of locating and characterizing potential resources. There is already considerable evidence from orbital and impact missions that the lunar poles harbor plausibly rich reservoirs of volatiles. The next step is to land on the Moon and assess the nature, “ore-grade”, and extractability of water ice and other materials. In support of this next step, a mission simulation was carried out on the island of Hawai'i in July of 2012. A robotic rover, provided by the Canadian Space Agency, carried several NASA ISRU-supporting instruments in a field test to address how such a mission might be carried out. This exercise was meant to test the ability to (a) locate and characterize volatiles, (b) acquire subsurface samples in a volatile-rich location, and (c) analyze the form and composition of the volatiles to determine their utility. This paper describes the successful demonstration of neutron spectroscopy as a prospecting and decision support system to locate and evaluate potential ISRU targets in the field exercise.

Solid phase microextraction-comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the analysis of honey volatiles.

PubMed

Cajka, Tomás; Hajslová, Jana; Cochran, Jack; Holadová, Katerina; Klimánková, Eva

2007-03-01

Head-space solid phase microextration (SPME), followed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GCxGC-TOFMS), has been implemented for the analysis of honey volatiles, with emphasis on the optimal selection of SPME fibre and the first- and second-dimension GC capillaries. From seven SPME fibres investigated, a divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) 50/30 microm fibre provided the best sorption capacity and the broadest range of volatiles extracted from the headspace of a mixed honey sample. A combination of DB-5ms x SUPELCOWAX 10 columns enabled the best resolution of sample components compared to the other two tested column configurations. Employing this powerful analytical strategy led to the identification of 164 volatile compounds present in a honey mixture during a 19-min GC run. Combination of this simple and inexpensive SPME-based sampling/concentration technique with the advanced separation/identification approach represented by GCxGC-TOFMS allows a rapid and comprehensive examination of the honey volatiles profile. In this way, the laboratory sample throughput can be increased significantly and, at the same time, the risk of erroneous identification, which cannot be avoided in one-dimensional GC separation, is minimised.

Micro- and Nanostructured Metal Oxide Chemical Sensors for Volatile Organic Compounds

NASA Technical Reports Server (NTRS)

Alim, M. A.; Penn, B. G.; Currie, J. R., Jr.; Batra, A. K.; Aggarwal, M. D.

2008-01-01

Aeronautic and space applications warrant the development of chemical sensors which operate in a variety of environments. This technical memorandum incorporates various kinds of chemical sensors and ways to improve their performance. The results of exploratory investigation of the binary composite polycrystalline thick-films such as SnO2-WO3, SnO2-In2O3, SnO2-ZnO for the detection of volatile organic compound (isopropanol) are reported. A short review of the present status of the new types of nanostructured sensors such as nanobelts, nanorods, nanotube, etc. based on metal oxides is presented.

Radiation Test Challenges for Scaled Commerical Memories

NASA Technical Reports Server (NTRS)

LaBel, Kenneth A.; Ladbury, Ray L.; Cohn, Lewis M.; Oldham, Timothy

2007-01-01

As sub-100nm CMOS technologies gather interest, the radiation effects performance of these technologies provide a significant challenge. In this talk, we shall discuss the radiation testing challenges as related to commercial memory devices. The focus will be on complex test and failure modes emerging in state-of-the-art Flash non-volatile memories (NVMs) and synchronous dynamic random access memories (SDRAMs), which are volatile. Due to their very high bit density, these device types are highly desirable for use in the natural space environment. In this presentation, we shall discuss these devices with emphasis on considerations for test and qualification methods required.

KSC-2013-3866

NASA Image and Video Library

2013-11-06

CAPE CANAVERAL, Fla. – Engineers and technicians move NASA's MAVEN spacecraft, inside payload fairing inside the Payload Hazardous Servicing Facility, or PHSF, into the airlock for mounting to a trailer for transport to Space Launch Complex 41 where it will be hoisted atop a United Launch Alliance Atlas V rocket that will lift it into space and on to Mars. MAVEN is short for Mars Atmosphere and Volatile Evolution. Photo credit: NASA/Kim Shiflett

KSC-2013-3867

NASA Image and Video Library

2013-11-06

CAPE CANAVERAL, Fla. – Engineers and technicians move NASA's MAVEN spacecraft, inside payload fairing inside the Payload Hazardous Servicing Facility, or PHSF, into the airlock for mounting to a trailer for transport to Space Launch Complex 41 where it will be hoisted atop a United Launch Alliance Atlas V rocket that will lift it into space and on to Mars. MAVEN is short for Mars Atmosphere and Volatile Evolution. Photo credit: NASA/Kim Shiflett

KSC-2013-3864

NASA Image and Video Library

2013-11-06

CAPE CANAVERAL, Fla. – Engineers and technicians move NASA's MAVEN spacecraft, inside payload fairing inside the Payload Hazardous Servicing Facility, or PHSF, into the airlock for mounting to a trailer for transport to Space Launch Complex 41 where it will be hoisted atop a United Launch Alliance Atlas V rocket that will lift it into space and on to Mars. MAVEN is short for Mars Atmosphere and Volatile Evolution. Photo credit: NASA/Kim Shiflett

KSC-2013-3865

NASA Image and Video Library

2013-11-06

CAPE CANAVERAL, Fla. – Engineers and technicians move NASA's MAVEN spacecraft, inside payload fairing inside the Payload Hazardous Servicing Facility, or PHSF, into the airlock for mounting to a trailer for transport to Space Launch Complex 41 where it will be hoisted atop a United Launch Alliance Atlas V rocket that will lift it into space and on to Mars. MAVEN is short for Mars Atmosphere and Volatile Evolution. Photo credit: NASA/Kim Shiflett

Low extractable wipers for cleaning space flight hardware

NASA Technical Reports Server (NTRS)

Tijerina, Veronica; Gross, Frederick C.

1986-01-01

There is a need for low extractable wipers for solvent cleaning of space flight hardware. Soxhlet extraction is the method utilized today by most NASA subcontractors, but there may be alternate methods to achieve the same results. The need for low non-volatile residue materials, the history of soxhlet extraction, and proposed alternate methods are discussed, as well as different types of wipers, test methods, and current standards.

Definition of a near real time microbiological monitor for space vehicles

NASA Technical Reports Server (NTRS)

Kilgore, Melvin V., Jr.; Zahorchak, Robert J.; Arendale, William F.

1989-01-01

Efforts to identify the ideal candidate to serve as the biological monitor on the space station Freedom are discussed. The literature review, the evaluation scheme, descriptions of candidate monitors, experimental studies, test beds, and culture techniques are discussed. Particular attention is given to descriptions of five candidate monitors or monitoring techniques: laser light scattering, primary fluorescence, secondary fluorescence, the volatile product detector, and the surface acoustic wave detector.

RESOLVE Projects: Lunar Water Resource Demonstration and Regolith Volatile Characterization

NASA Technical Reports Server (NTRS)

2008-01-01

To sustain affordable human and robotic space exploration, the ability to live off the land at the exploration site will be essential. NASA calls this ability in situ resource utilization (ISRU) and is focusing on finding ways to sustain missions first on the Moon and then on Mars. The ISRU project aims to develop capabilities to technology readiness level 6 for the Robotic Lunar Exploration Program and early human missions returning to the Moon. NASA is concentrating on three primary areas of ISRU: (1) excavating, handling, and moving lunar regolith, (2) extracting oxygen from lunar regolith, and (3) finding, characterizing, extracting, separating, and storing volatile lunar resources, especially in the permanently shadowed polar craters. To meet the challenges related to technology development for these three primary focus areas, the Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE) project was initiated in February 2005, through funding by the Exploration Systems Mission Directorate. RESOLVE's objectives are to develop requirements and conceptual designs and to perform breadboard concept verification testing of each experiment module. The final goal is to deliver a flight prototype unit that has been tested in a relevant lunar polar environment. Here we report progress toward the third primary area creating ways to find, characterize, extract, separate, and store volatile lunar resources. The tasks include studying thermal, chemical, and electrical ways to collect such volatile resources as hydrogen, water, nitrogen, methane, and ammonia. We approached this effort through two subtasks: lunar water resource demonstration (LWRD) and regolith volatile characterization (RVC).

Near Real-Time Prospecting for Lunar Volatiles: Demonstrating RESOLVE Science in the Field

NASA Astrophysics Data System (ADS)

Elphic, R. C.; Colaprete, A.; Heldmann, J. L.; Mattes, G.; Ennico, K.; Sanders, G. B.; Quinn, J.; Fritzler, E.; Marinova, M.; Roush, T. L.; Stoker, C.; Larson, W.; Picard, M.; McMurray, R.; Morse, S.

2012-12-01

The Regolith and Environment Science and Oxygen & Lunar Volatile Extraction (RESOLVE) project aims to demonstrate the utility of "in situ resource utilization". In situ resource utilization (ISRU) is a way to rebalance the economics of spaceflight by reducing or eliminating materials that must be brought up from Earth and placed on the surface of the Moon for human use. RESOLVE is developing a rover-borne payload that (1) can locate near subsurface volatiles, (2) excavate and analyze samples of the volatile-bearing regolith, and (3) demonstrate the form, extractability and usefulness of the materials. Such investigations are important not only for ISRU but are also critically important for understanding the scientific nature of these intriguing lunar polar volatile deposits. Temperature models and orbital data suggest near surface volatile concentrations may exist at briefly lit lunar polar locations outside persistently shadowed regions. A lunar rover could be remotely operated at some of these locations for the 4-7 days of expected sunlight at relatively low cost. In July 2012 the RESOLVE project conducted a full-scale field demonstration. In particular, the ability to perform the real-time measurement analysis necessary to search for volatiles and the ability to combine the various measurement techniques to meet the mission measurement and science goals. With help from the Pacific International Space Center for Exploration Systems (PISCES), a lunar rover prototype (provided by the Canadian Space Agency) was equipped with prospecting instruments (neutron spectrometer and near-infrared spectrometer), subsurface access and sampling tools, including both an auger and coring drill (provided by CSA) and subsurface sample analysis instrumentation, including a sample oven system, the Oxygen and Volatile Extraction Node (OVEN), and Gas Chromatograph / Mass Spectrometer system, the Lunar Advanced Volatile Analysis (LAVA) system. Given the relatively short time period this lunar mission is being designed to, prospecting needs to occur in near real-time. The two prospecting instruments are the neutron and NIR spectrometers. In the field demo a small radioactive source was provided the neutron flux. The NIR spectrometer, which includes its own light source, looks at surface reflectance for signatures of bound H2O/OH and general mineralogy. Once a "hot spot" was found by the prospecting instruments, the drill could either auger or core. The auger drill worked to a depth of 50 cm and is monitored with a drill camera and the NIR spectrometer. As cuttings are brought up the NIR spectra is monitored. If a particular location is considered of high-interest then the decision to core could be made. The coring drill (a push-tube) allowed a 1-meter sample to be acquired processed by the OVEN/LAVA sys-tem. This presentation will provide details as how these instruments worked together and how and if the planned measurements and science was obtained.

Near Real Time Prospecting for Lunar Volatiles: Demonstrating RESOLVE Science in the Field

NASA Technical Reports Server (NTRS)

Elphic, Richard; Colaprete, Anthony; Heldmann, Jennifer; Mattes, Gregory W.; Ennico, Kimberly; Sanders, Gerald; Quinn, Jacqueline; Tegnerud, Erin Leigh; Marinova, Margarita; Larson, William E.;

Simulating the component counts of combinatorial structures.

PubMed

Arratia, Richard; Barbour, A D; Ewens, W J; Tavaré, Simon

2018-02-09

This article describes and compares methods for simulating the component counts of random logarithmic combinatorial structures such as permutations and mappings. We exploit the Feller coupling for simulating permutations to provide a very fast method for simulating logarithmic assemblies more generally. For logarithmic multisets and selections, this approach is replaced by an acceptance/rejection method based on a particular conditioning relationship that represents the distribution of the combinatorial structure as that of independent random variables conditioned on a weighted sum. We show how to improve its acceptance rate. We illustrate the method by estimating the probability that a random mapping has no repeated component sizes, and establish the asymptotic distribution of the difference between the number of components and the number of distinct component sizes for a very general class of logarithmic structures. Copyright © 2018. Published by Elsevier Inc.

Double Resummation for Higgs Production

NASA Astrophysics Data System (ADS)

Bonvini, Marco; Marzani, Simone

2018-05-01

We present the first double-resummed prediction of the inclusive cross section for the main Higgs production channel in proton-proton collisions, namely, gluon fusion. Our calculation incorporates to all orders in perturbation theory two distinct towers of logarithmic corrections which are enhanced, respectively, at threshold, i.e., large x , and in the high-energy limit, i.e., small x . Large-x logarithms are resummed to next-to-next-to-next-to-leading logarithmic accuracy, while small-x ones to leading logarithmic accuracy. The double-resummed cross section is furthermore matched to the state-of-the-art fixed-order prediction at next-to-next-to-next-to-leading accuracy. We find that double resummation corrects the Higgs production rate by 2% at the currently explored center-of-mass energy of 13 TeV and its impact reaches 10% at future circular colliders at 100 TeV.

Sensitivity analysis of simulated SOA loadings using a variance-based statistical approach: SENSITIVITY ANALYSIS OF SOA

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

Shrivastava, Manish; Zhao, Chun; Easter, Richard C.

We investigate the sensitivity of secondary organic aerosol (SOA) loadings simulated by a regional chemical transport model to 7 selected tunable model parameters: 4 involving emissions of anthropogenic and biogenic volatile organic compounds, anthropogenic semi-volatile and intermediate volatility organics (SIVOCs), and NOx, 2 involving dry deposition of SOA precursor gases, and one involving particle-phase transformation of SOA to low volatility. We adopt a quasi-Monte Carlo sampling approach to effectively sample the high-dimensional parameter space, and perform a 250 member ensemble of simulations using a regional model, accounting for some of the latest advances in SOA treatments based on our recentmore » work. We then conduct a variance-based sensitivity analysis using the generalized linear model method to study the responses of simulated SOA loadings to the tunable parameters. Analysis of SOA variance from all 250 simulations shows that the volatility transformation parameter, which controls whether particle-phase transformation of SOA from semi-volatile SOA to non-volatile is on or off, is the dominant contributor to variance of simulated surface-level daytime SOA (65% domain average contribution). We also split the simulations into 2 subsets of 125 each, depending on whether the volatility transformation is turned on/off. For each subset, the SOA variances are dominated by the parameters involving biogenic VOC and anthropogenic SIVOC emissions. Furthermore, biogenic VOC emissions have a larger contribution to SOA variance when the SOA transformation to non-volatile is on, while anthropogenic SIVOC emissions have a larger contribution when the transformation is off. NOx contributes less than 4.3% to SOA variance, and this low contribution is mainly attributed to dominance of intermediate to high NOx conditions throughout the simulated domain. The two parameters related to dry deposition of SOA precursor gases also have very low contributions to SOA variance. This study highlights the large sensitivity of SOA loadings to the particle-phase transformation of SOA volatility, which is neglected in most previous models.« less

Dynamics of Metabolite Induction in Fungal Co-cultures by Metabolomics at Both Volatile and Non-volatile Levels

PubMed Central

Azzollini, Antonio; Boggia, Lorenzo; Boccard, Julien; Sgorbini, Barbara; Lecoultre, Nicole; Allard, Pierre-Marie; Rubiolo, Patrizia; Rudaz, Serge; Gindro, Katia; Bicchi, Carlo; Wolfender, Jean-Luc

2018-01-01

Fungal co-cultivation has emerged as a promising way for activating cryptic biosynthetic pathways and discovering novel antimicrobial metabolites. For the success of such studies, a key element remains the development of standardized co-cultivation methods compatible with high-throughput analytical procedures. To efficiently highlight induction processes, it is crucial to acquire a holistic view of intermicrobial communication at the molecular level. To tackle this issue, a strategy was developed based on the miniaturization of fungal cultures that allows for a concomitant survey of induction phenomena in volatile and non-volatile metabolomes. Fungi were directly grown in vials, and each sample was profiled by head space solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS), while the corresponding solid culture medium was analyzed by liquid chromatography high resolution mass spectrometry (LC-HRMS) after solvent extraction. This strategy was implemented for the screening of volatile and non-volatile metabolite inductions in an ecologically relevant fungal co-culture of Eutypa lata (Pers.) Tul. & C. Tul. (Diatrypaceae) and Botryosphaeria obtusa (Schwein.) Shoemaker (Botryosphaeriaceae), two wood-decaying fungi interacting in the context of esca disease of grapevine. For a comprehensive evaluation of the results, a multivariate data analysis combining Analysis of Variance and Partial Least Squares approaches, namely AMOPLS, was used to explore the complex LC-HRMS and GC-MS datasets and highlight dynamically induced compounds. A time-series study was carried out over 9 days, showing characteristic metabolite induction patterns in both volatile and non-volatile dimensions. Relevant links between the dynamics of expression of specific metabolite production were observed. In addition, the antifungal activity of 2-nonanone, a metabolite incrementally produced over time in the volatile fraction, was assessed against Eutypa lata and Botryosphaeria obtusa in an adapted bioassay set for volatile compounds. This compound has shown antifungal activity on both fungi and was found to be co-expressed with a known antifungal compound, O-methylmellein, induced in solid media. This strategy could help elucidate microbial inter- and intra-species cross-talk at various levels. Moreover, it supports the study of concerted defense/communication mechanisms for efficiently identifying original antimicrobials. PMID:29459851

Evaluation of bio-optical algorithms to remotely sense marine primary production from space

NASA Technical Reports Server (NTRS)

Berthelot, Beatrice; Deschamps, Pierre-Yves

1994-01-01

In situ bio-optical measurements from several oceanographic campaigns were analyzed to derive a direct relationship between water column primary production P (sub t) ocean color as expressed by the ratio of reflectances R (sub 1) at 440 nm and R (sub 3) at 550 nm and photosynthetically available radiation (PAR). The study is restricted to the Morel case I waters for which the following algorithm is proposed: log (P(sub f)) = -4.286 - 1.390 log (R(sub 1)/R(sub3)) + 0.621 log (PAR), with P(sub t) in g C m(exp -2)/d and PAR in J m(exp -2)/d. Using this algorithm the rms accuracy of primary production estimate is 0.17 on a logarithmic scale, i.e., a factor of 1.5. Using spectral reflectance measurements in the entire visible spectral range, the central wavelength, spectral bandwidth, and radiometric noise level requirements are investigated for the channels to be used by an ocean color space mission dedicated to estimating global marine primary production and the associated carbon fluxes. Nearly all the useful information is provided by two channels centered at 440 nm and 550 nm, but the accuracy of primary production estimate appears weakly sensitive to spectral bandwidth, which, consequently, may be enlarged by several tens of nanometers. The sensitivity to radiometric noise, on the contrary, is strong, and a noise equivalent reflectance of 0.005 degraded the accuracy on the primary production estimate by a factor 2 (0.14-0.25 on a logarithmic scale). The results should be applicable to evaluating the primary production of oligotrophic and mesotrophic waters, which constitute most of the open ocean.

KENNEDY SPACE CENTER, FLA. -- Lanfang Levine, with Dynamac Corp., helps install a Dionex DX-500 IC/HPLC system in the Space Life Sciences Lab. The equipment will enable analysis of volatile compounds, such as from plants. The 100,000 square-foot facility houses labs for NASA’s ongoing research efforts, microbiology/microbial ecology studies and analytical chemistry labs. Also calling the new lab home are facilities for space flight-experiment and flight-hardware development, new plant growth chambers, and an Orbiter Environment Simulator that will be used to conduct ground control experiments in simulated flight conditions for space flight experiments. The SLS Lab, formerly known as the Space Experiment Research and Processing Laboratory or SERPL, provides space for NASA’s Life Sciences Services contractor Dynamac Corporation, Bionetics Corporation, and researchers from the University of Florida. NASA’s Office of Biological and Physical Research will use the facility for processing life sciences experiments that will be conducted on the International Space Station. The SLS Lab is the magnet facility for the International Space Research Park at KSC being developed in partnership with Florida Space Authority.

NASA Image and Video Library

2004-01-05

KENNEDY SPACE CENTER, FLA. -- Lanfang Levine, with Dynamac Corp., helps install a Dionex DX-500 IC/HPLC system in the Space Life Sciences Lab. The equipment will enable analysis of volatile compounds, such as from plants. The 100,000 square-foot facility houses labs for NASA’s ongoing research efforts, microbiology/microbial ecology studies and analytical chemistry labs. Also calling the new lab home are facilities for space flight-experiment and flight-hardware development, new plant growth chambers, and an Orbiter Environment Simulator that will be used to conduct ground control experiments in simulated flight conditions for space flight experiments. The SLS Lab, formerly known as the Space Experiment Research and Processing Laboratory or SERPL, provides space for NASA’s Life Sciences Services contractor Dynamac Corporation, Bionetics Corporation, and researchers from the University of Florida. NASA’s Office of Biological and Physical Research will use the facility for processing life sciences experiments that will be conducted on the International Space Station. The SLS Lab is the magnet facility for the International Space Research Park at KSC being developed in partnership with Florida Space Authority.

Ice in space: An experimental and theoretical investigation

NASA Technical Reports Server (NTRS)

Patashnick, H.; Rupprecht, G.

1977-01-01

Basic knowledge is provided on the behavior of ice and ice particles under a wide variety of conditions including those of interplanetary space. This information and, in particular, the lifetime of ice particles as a function of solar distance is an absolute requirement for a proper interpretation of photometric profiles in comets. Because fundamental properties of ice and ice particles are developed in this report, the applicability of this information extends beyond the realm of comets into any area where volatile particles exist, be it in space or in the earth's atmosphere.

A Chemical Containment Model for the General Purpose Work Station

NASA Technical Reports Server (NTRS)

Flippen, Alexis A.; Schmidt, Gregory K.

1994-01-01

Contamination control is a critical safety requirement imposed on experiments flying on board the Spacelab. The General Purpose Work Station, a Spacelab support facility used for life sciences space flight experiments, is designed to remove volatile compounds from its internal airpath and thereby minimize contamination of the Spacelab. This is accomplished through the use of a large, multi-stage filter known as the Trace Contaminant Control System. Many experiments planned for the Spacelab require the use of toxic, volatile fixatives in order to preserve specimens prior to postflight analysis. The NASA-Ames Research Center SLS-2 payload, in particular, necessitated the use of several toxic, volatile compounds in order to accomplish the many inflight experiment objectives of this mission. A model was developed based on earlier theories and calculations which provides conservative predictions of the resultant concentrations of these compounds given various spill scenarios. This paper describes the development and application of this model.

The Interaction of Spacecraft Cabin Atmospheric Quality and Water Processing System Performance

NASA Technical Reports Server (NTRS)

Perry, Jay L.; Croomes, Scott D. (Technical Monitor)

2002-01-01

Although designed to remove organic contaminants from a variety of waste water streams, the planned U.S.- and present Russian-provided water processing systems onboard the International Space Station (ISS) have capacity limits for some of the more common volatile cleaning solvents used for housekeeping purposes. Using large quantities of volatile cleaning solvents during the ground processing and in-flight operational phases of a crewed spacecraft such as the ISS can lead to significant challenges to the water processing systems. To understand the challenges facing the management of water processing capacity, the relationship between cabin atmospheric quality and humidity condensate loading is presented. This relationship is developed as a tool to determine the cabin atmospheric loading that may compromise water processing system performance. A comparison of cabin atmospheric loading with volatile cleaning solvents from ISS, Mir, and Shuttle are presented to predict acceptable limits to maintain optimal water processing system performance.

A Computer Model for Analyzing Volatile Removal Assembly

NASA Technical Reports Server (NTRS)

Guo, Boyun

2010-01-01

A computer model simulates reactional gas/liquid two-phase flow processes in porous media. A typical process is the oxygen/wastewater flow in the Volatile Removal Assembly (VRA) in the Closed Environment Life Support System (CELSS) installed in the International Space Station (ISS). The volatile organics in the wastewater are combusted by oxygen gas to form clean water and carbon dioxide, which is solved in the water phase. The model predicts the oxygen gas concentration profile in the reactor, which is an indicator of reactor performance. In this innovation, a mathematical model is included in the computer model for calculating the mass transfer from the gas phase to the liquid phase. The amount of mass transfer depends on several factors, including gas-phase concentration, distribution, and reaction rate. For a given reactor dimension, these factors depend on pressure and temperature in the reactor and composition and flow rate of the influent.

Recognition of anaerobic bacterial isolates in vitro using electronic nose technology.

PubMed

Pavlou, A; Turner, A P F; Magan, N

2002-01-01

Use of an electronic nose (e.nose) system to differentiation between anaerobic bacteria grown in vitro on agar media. Cultures of Clostridium spp. (14 strains) and Bacteroides fragilis (12 strains) were grown on blood agar plates and incubated in sampling bags for 30 min before head space analysis of the volatiles. Qualitative analyses of the volatile production patterns was carried out using an e.nose system with 14 conducting polymer sensors. Using data analysis techniques such as principal components analysis (PCA), genetic algorithms and neural networks it was possible to differentiate between agar blanks and individual species which accounted for all the data. A total of eight unknowns were correctly discriminated into the bacterial groups. This is the first report of in vitro complex volatile pattern recognition and differentiation of anaerobic pathogens. These results suggest the potential for application of e.nose technology in early diagnosis of microbial pathogens of medical importance.

A factorization approach to next-to-leading-power threshold logarithms

NASA Astrophysics Data System (ADS)

Bonocore, D.; Laenen, E.; Magnea, L.; Melville, S.; Vernazza, L.; White, C. D.

2015-06-01

Threshold logarithms become dominant in partonic cross sections when the selected final state forces gluon radiation to be soft or collinear. Such radiation factorizes at the level of scattering amplitudes, and this leads to the resummation of threshold logarithms which appear at leading power in the threshold variable. In this paper, we consider the extension of this factorization to include effects suppressed by a single power of the threshold variable. Building upon the Low-Burnett-Kroll-Del Duca (LBKD) theorem, we propose a decomposition of radiative amplitudes into universal building blocks, which contain all effects ultimately responsible for next-to-leading-power (NLP) threshold logarithms in hadronic cross sections for electroweak annihilation processes. In particular, we provide a NLO evaluation of the radiative jet function, responsible for the interference of next-to-soft and collinear effects in these cross sections. As a test, using our expression for the amplitude, we reproduce all abelian-like NLP threshold logarithms in the NNLO Drell-Yan cross section, including the interplay of real and virtual emissions. Our results are a significant step towards developing a generally applicable resummation formalism for NLP threshold effects, and illustrate the breakdown of next-to-soft theorems for gauge theory amplitudes at loop level.

The ABC (in any D) of logarithmic CFT

NASA Astrophysics Data System (ADS)

Hogervorst, Matthijs; Paulos, Miguel; Vichi, Alessandro

2017-10-01

Logarithmic conformal field theories have a vast range of applications, from critical percolation to systems with quenched disorder. In this paper we thoroughly examine the structure of these theories based on their symmetry properties. Our analysis is model-independent and holds for any spacetime dimension. Our results include a determination of the general form of correlation functions and conformal block decompositions, clearing the path for future bootstrap applications. Several examples are discussed in detail, including logarithmic generalized free fields, holographic models, self-avoiding random walks and critical percolation.

International Coordination of Exploring and Using Lunar Polar Volatiles

NASA Technical Reports Server (NTRS)

Gruener, J. E.; Suzuki, N. H.; Carpenter, J. D.

2016-01-01

Fourteen international space agencies are participating in the International Space Exploration Coordination Group (ISECG), working together to advance a long-range strategy for human and robotic space exploration beyond low earth orbit. The ISECG is a voluntary, non-binding international coordination mechanism through which individual agencies may exchange information regarding interests, objectives, and plans in space exploration with the goal of strengthening both individual exploration programs as well as the collective effort. The ISECG has developed a Global Exploration Roadmap (GER) that reflects the coordinated international dialog and continued preparation for exploration beyond low-Earth orbit, beginning with the Moon and cis-lunar space, and continuing to near-Earth asteroids, and Mars.

KSC-2013-3863

NASA Image and Video Library

2013-11-06

CAPE CANAVERAL, Fla. – Engineers and technicians get ready to move NASA's MAVEN spacecraft, inside payload fairing inside the Payload Hazardous Servicing Facility, or PHSF, into the airlock for mounting to a trailer for transport to Space Launch Complex 41 where it will be hoisted atop a United Launch Alliance Atlas V rocket that will lift it into space and on to Mars. MAVEN is short for Mars Atmosphere and Volatile Evolution. Photo credit: NASA/Kim Shiflett

US Space Superiority: It was Good While it Lasted; Exploring the Contesting and Congesting of the Space Domain

DTIC Science & Technology

2012-04-11

of the Graduation Requirements Advisors: Dr. John T. Ackerman Dr. Kathleen Mahoney -Norris Maxwell Air Force...like to thank my advisors, Dr. John Ackerman and Dr. Kathleen Mahoney -Norris, for creating and administering the Future Trends course with such...Security Act of 2011. 49 Newman , Andrew. The Truth About Oil. 50 Miner, Dan. Beyond Oil: Appendix B: Fuel Depletion and Peak Oil Guarantee Volatility

Operator algebra as an application of logarithmic representation of infinitesimal generators

NASA Astrophysics Data System (ADS)

Iwata, Yoritaka

2018-02-01

The operator algebra is introduced based on the framework of logarithmic representation of infinitesimal generators. In conclusion a set of generally-unbounded infinitesimal generators is characterized as a module over the Banach algebra.

Entropy production of doubly stochastic quantum channels

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

Müller-Hermes, Alexander, E-mail: muellerh@posteo.net; Department of Mathematical Sciences, University of Copenhagen, 2100 Copenhagen; Stilck França, Daniel, E-mail: dsfranca@mytum.de

2016-02-15

We study the entropy increase of quantum systems evolving under primitive, doubly stochastic Markovian noise and thus converging to the maximally mixed state. This entropy increase can be quantified by a logarithmic-Sobolev constant of the Liouvillian generating the noise. We prove a universal lower bound on this constant that stays invariant under taking tensor-powers. Our methods involve a new comparison method to relate logarithmic-Sobolev constants of different Liouvillians and a technique to compute logarithmic-Sobolev inequalities of Liouvillians with eigenvectors forming a projective representation of a finite abelian group. Our bounds improve upon similar results established before and as an applicationmore » we prove an upper bound on continuous-time quantum capacities. In the last part of this work we study entropy production estimates of discrete-time doubly stochastic quantum channels by extending the framework of discrete-time logarithmic-Sobolev inequalities to the quantum case.« less

Very low scale Coleman-Weinberg inflation with nonminimal coupling

NASA Astrophysics Data System (ADS)

Kaneta, Kunio; Seto, Osamu; Takahashi, Ryo

2018-03-01

We study viable small-field Coleman-Weinberg (CW) inflation models with the help of nonminimal coupling to gravity. The simplest small-field CW inflation model (with a low-scale potential minimum) is incompatible with the cosmological constraint on the scalar spectral index. However, there are possibilities to make the model realistic. First, we revisit the CW inflation model supplemented with a linear potential term. We next consider the CW inflation model with a logarithmic nonminimal coupling and illustrate that the model can open a new viable parameter space that includes the model with a linear potential term. We also show parameter spaces where the Hubble scale during the inflation can be as small as 10-4 GeV , 1 GeV, 1 04 GeV , and 1 08 GeV for the number of e -folds of 40, 45, 50, and 55, respectively, with other cosmological constraints being satisfied.

Study to investigate and evaluate means of optimizing the Ku-band combined radar/communication functions for the space shuttle

NASA Technical Reports Server (NTRS)

Weber, C. L.; Udalov, S.; Alem, W.

1977-01-01

The performance of the space shuttle orbiter's Ku-Band integrated radar and communications equipment is analyzed for the radar mode of operation. The block diagram of the rendezvous radar subsystem is described. Power budgets for passive target detection are calculated, based on the estimated values of system losses. Requirements for processing of radar signals in the search and track modes are examined. Time multiplexed, single-channel, angle tracking of passive scintillating targets is analyzed. Radar performance in the presence of main lobe ground clutter is considered and candidate techniques for clutter suppression are discussed. Principal system parameter drivers are examined for the case of stationkeeping at ranges comparable to target dimension. Candidate ranging waveforms for short range operation are analyzed and compared. The logarithmic error discriminant utilized for range, range rate and angle tracking is formulated and applied to the quantitative analysis of radar subsystem tracking loops.

Complex reflection groups, logarithmic connections and bi-flat F-manifolds

NASA Astrophysics Data System (ADS)

Arsie, Alessandro; Lorenzoni, Paolo

2017-10-01

We show that bi-flat F-manifolds can be interpreted as natural geometrical structures encoding the almost duality for Frobenius manifolds without metric. Using this framework, we extend Dubrovin's duality between orbit spaces of Coxeter groups and Veselov's ěe -systems, to the orbit spaces of exceptional well-generated complex reflection groups of rank 2 and 3. On the Veselov's ěe -systems side, we provide a generalization of the notion of ěe -systems that gives rise to a dual connection which coincides with a Dunkl-Kohno-type connection associated with such groups. In particular, this allows us to treat on the same ground several different examples including Coxeter and Shephard groups. Remarkably, as a by-product of our results, we prove that in some examples, basic flat invariants are not uniquely defined. As far as we know, such a phenomenon has never been pointed out before.

Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

PubMed

Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

2008-08-01

We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

Space Weather Impact on Pipeline in La Plata City, Argentine

NASA Astrophysics Data System (ADS)

Gianibelli, J. C.; Dovico, R. O.; Peirtti, R. O.; Pretel, R. O.; Garcia, R. E.; Quaglino, N. M.

2007-05-01

In the Sun-Earth connection, some of the most important characteristic events involved are the Coronal Mass Ejections (CME) and the high speed particle streams events coming from the Coronal Holes at the Sun. These interplanetary events produce effects on space and ground-based technology. In the present work, the geomagnetic storm recorded at Las Acacias Digital Magnetic Observatory (LAS, Lat.:-35º.0; Long.: 302º.3) produced by a particle stream from a solar coronal hole and their relationship with the induction effects caused on a pipeline in the shore of La Plata city, Argentine. The result shows an increase of the induced current correlated with the registered geomagnetic storm. Also, the magnetically calm days are analized. It is concluded that the amplitude of induced current intensity verifies a logarithmic relation with the amplitude of total magnetic intensity recorded in Las Acacias Observatory.

The characteristics of low-speed streaks in the near-wall region of a turbulent boundary layer

NASA Astrophysics Data System (ADS)

Smith, C. R.; Metzler, S. P.

1983-04-01

The discovery of an instantaneous spanwise velocity distribution consisting of alternative zones of high- and low-speed fluid which develop in the viscous sublayer and extend into the logarithmic region was one of the first clues to the existence of an ordered structure within a turbulent boundary layer. The present investigation is concerned with quantitative flow-visualization results obtained with the aid of a high-speed video flow visualization system which permits the detailed visual examination of both the statistics and characteristics of low-speed streaks over a much wider range of Reynolds numbers than has been possible before. Attention is given to streak appearance, mean streak spacing, the spanwise distribution of streaks, streak persistence, and aspects of streak merging and intermittency. The results indicate that the statistical characteristics of the spanwise spacing of low-speed streaks are essentially invariant with Reynolds number.

Logarithms in the Year 10 A.C.

ERIC Educational Resources Information Center

Kalman, Dan; Mitchell, Charles E.

1981-01-01

An alternative application of logarithms in the high school algebra curriculum that is not undermined by the existence and widespread availability of calculators is presented. The importance and use of linear relationships are underscored in the proposed lessons. (MP)

Method and apparatus for measuring volatile compounds in an aqueous solution

DOEpatents

Gilmore, Tyler J [Pasco, WA; Cantrell, Kirk J [West Richland, WA

2002-07-16

The present invention is an improvement to the method and apparatus for measuring volatile compounds in an aqueous solution. The apparatus is a chamber with sides and two ends, where the first end is closed. The chamber contains a solution volume of the aqueous solution and a gas that is trapped within the first end of the chamber above the solution volume. The gas defines a head space within the chamber above the solution volume. The chamber may also be a cup with the second end. open and facing down and submerged in the aqueous solution so that the gas defines the head space within the cup above the solution volume. The cup can also be entirely submerged in the aqueous solution. The second end of the. chamber may be closed such that the chamber can be used while resting on a flat surface such as a bench. The improvement is a sparger for mixing the gas with the solution volume. The sparger can be a rotating element such as a propeller on a shaft or a cavitating impeller. The sparger can also be a pump and nozzle where the pump is a liquid pump and the nozzle is a liquid spray nozzle open, to the head space for spraying the solution volume into the head space of gas. The pump could also be a gas pump and the nozzle a gas nozzle submerged in the solution volume for spraying the head space gas into the solution volume.

Entanglement Entropy in Two-Dimensional String Theory.

PubMed

Hartnoll, Sean A; Mazenc, Edward A

2015-09-18

To understand an emergent spacetime is to understand the emergence of locality. Entanglement entropy is a powerful diagnostic of locality, because locality leads to a large amount of short distance entanglement. Two-dimensional string theory is among the very simplest instances of an emergent spatial dimension. We compute the entanglement entropy in the large-N matrix quantum mechanics dual to two-dimensional string theory in the semiclassical limit of weak string coupling. We isolate a logarithmically large, but finite, contribution that corresponds to the short distance entanglement of the tachyon field in the emergent spacetime. From the spacetime point of view, the entanglement is regulated by a nonperturbative "graininess" of space.

Renormalizability of quasiparton distribution functions

DOE PAGES

Ishikawa, Tomomi; Ma, Yan-Qing; Qiu, Jian-Wei; ...

2017-11-21

Quasi-parton distribution functions have received a lot of attentions in both perturbative QCD and lattice QCD communities in recent years because they not only carry good information on the parton distribution functions, but also could be evaluated by lattice QCD simulations. However, unlike the parton distribution functions, the quasi-parton distribution functions have perturbative ultraviolet power divergences because they are not defined by twist-2 operators. Here in this article, we identify all sources of ultraviolet divergences for the quasi-parton distribution functions in coordinate-space, and demonstrated that power divergences, as well as all logarithmic divergences can be renormalized multiplicatively to all ordersmore » in QCD perturbation theory.« less

Global dynamics and diffusion in triaxial galactic models

NASA Astrophysics Data System (ADS)

Papaphilippou, Y.

We apply the Frequency Map Analysis method to the 3--dimensional logarithmic galactic potential in order to clarify the dynamical behaviour of triaxial power--law galactic models. All the fine dynamical details are displayed in the complete frequency map, a direct representation of the system's Arnol'd web. The influence of resonant lines and the extent of the chaotic zones are directly associated with the physical space of the system. Some new results related with the diffusion of galactic orbits are also discussed. This approach reveals many unknown dynamical features of triaxial galactic potentials and provides strong indications that chaos should be an innate characteristic of triaxial configurations.

Renormalizability of quasiparton distribution functions

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

Ishikawa, Tomomi; Ma, Yan-Qing; Qiu, Jian-Wei

Quasi-parton distribution functions have received a lot of attentions in both perturbative QCD and lattice QCD communities in recent years because they not only carry good information on the parton distribution functions, but also could be evaluated by lattice QCD simulations. However, unlike the parton distribution functions, the quasi-parton distribution functions have perturbative ultraviolet power divergences because they are not defined by twist-2 operators. Here in this article, we identify all sources of ultraviolet divergences for the quasi-parton distribution functions in coordinate-space, and demonstrated that power divergences, as well as all logarithmic divergences can be renormalized multiplicatively to all ordersmore » in QCD perturbation theory.« less

Application of a hybrid computer to sweep frequency data processing

NASA Technical Reports Server (NTRS)

Milner, E. J.; Bruton, W. M.

1973-01-01

A hybrid computer program is presented which can process as many as 10 channels of sweep frequency data simultaneously. The program needs only the sine sweep signal used to drive the system, and its correponding quadrature component, to process the data. It can handle a maximum frequency range of 0.5 to 500 hertz. Magnitude and phase are calculated at logarithmically spaced points covering the frequency range of interest. When the sweep is completed, these results are stored in digital form. Thus, a tabular listing and/or a plot of any processed data channel or the transfer function relating any two of them is immediately available.

Multilayer neural networks with extensively many hidden units.

PubMed

Rosen-Zvi, M; Engel, A; Kanter, I

2001-08-13

The information processing abilities of a multilayer neural network with a number of hidden units scaling as the input dimension are studied using statistical mechanics methods. The mapping from the input layer to the hidden units is performed by general symmetric Boolean functions, whereas the hidden layer is connected to the output by either discrete or continuous couplings. Introducing an overlap in the space of Boolean functions as order parameter, the storage capacity is found to scale with the logarithm of the number of implementable Boolean functions. The generalization behavior is smooth for continuous couplings and shows a discontinuous transition to perfect generalization for discrete ones.

Compact Holographic Data Storage

NASA Technical Reports Server (NTRS)

Chao, T. H.; Reyes, G. F.; Zhou, H.

2001-01-01

NASA's future missions would require massive high-speed onboard data storage capability to Space Science missions. For Space Science, such as the Europa Lander mission, the onboard data storage requirements would be focused on maximizing the spacecraft's ability to survive fault conditions (i.e., no loss in stored science data when spacecraft enters the 'safe mode') and autonomously recover from them during NASA's long-life and deep space missions. This would require the development of non-volatile memory. In order to survive in the stringent environment during space exploration missions, onboard memory requirements would also include: (1) survive a high radiation environment (1 Mrad), (2) operate effectively and efficiently for a very long time (10 years), and (3) sustain at least a billion write cycles. Therefore, memory technologies requirements of NASA's Earth Science and Space Science missions are large capacity, non-volatility, high-transfer rate, high radiation resistance, high storage density, and high power efficiency. JPL, under current sponsorship from NASA Space Science and Earth Science Programs, is developing a high-density, nonvolatile and rad-hard Compact Holographic Data Storage (CHDS) system to enable large-capacity, high-speed, low power consumption, and read/write of data in a space environment. The entire read/write operation will be controlled with electrooptic mechanism without any moving parts. This CHDS will consist of laser diodes, photorefractive crystal, spatial light modulator, photodetector array, and I/O electronic interface. In operation, pages of information would be recorded and retrieved with random access and high-speed. The nonvolatile, rad-hard characteristics of the holographic memory will provide a revolutionary memory technology meeting the high radiation challenge facing the Europa Lander mission. Additional information is contained in the original extended abstract.

Characterization of the volatile profile of Antarctic bacteria by using solid-phase microextraction-gas chromatography-mass spectrometry.

PubMed

Romoli, Riccardo; Papaleo, Maria Cristiana; de Pascale, Donatella; Tutino, Maria Luisa; Michaud, Luigi; LoGiudice, Angelina; Fani, Renato; Bartolucci, Gianluca

2011-10-01

Bacteria belonging to the Burkholderia cepacia complex (Bcc) are significant pathogens in Cystic Fibrosis (CF) patients and are resistant to a plethora of antibiotics. In this context, microorganisms from Antarctica are interesting because they produce antimicrobial compounds inhibiting the growth of other bacteria. This is particularly true for bacteria isolated from Antarctic sponges. The aim of this work was to characterize a set of Antarctic bacteria for their ability to produce new natural drugs that could be exploited in the control of infections in CF patients by Bcc bacteria. Hence, 11 bacterial strains allocated to different genera (e.g., Pseudoalteromonas, Arthrobacter and Psychrobacter) were tested for their ability to inhibit the growth of 21 Bcc strains and some other human pathogens. All these bacteria completely inhibited the growth of most, if not all, Bcc strains, suggesting a highly specific activity toward Bcc strains. Experimental evidences showed that the antimicrobial compounds are small volatile organic compounds, and are constitutively produced via an unknown pathway. The microbial volatile profile was obtained by SPME-GC-MS within the m/z interval of 40-450. Solid phase micro extraction technique affords the possibility to extract the volatile compounds in head space with a minimal sample perturbation. Principal component analysis and successive cluster discriminant analysis was applied to evaluate the relationships among the volatile organic compounds with the aim of classifying the microorganisms by their volatile profile. These data highlight the potentiality of Antarctic bacteria as novel sources of antibacterial substances to face Bcc infections in CF patients. Copyright © 2011 John Wiley & Sons, Ltd.

The role of Environmental Health System air quality monitors in Space Station Contingency Operations

NASA Technical Reports Server (NTRS)

Limero, Thomas F.; Wilson, Steve; Perlot, Susan; James, John

1992-01-01

This paper describes the Space Station Freedom (SSF) Environmental Health System's air-quality monitoring strategy and instrumentation. A two-tier system has been developed, consisting of first-alert instruments that warn the crew of airborne contamination and a volatile organic analyzer that can identify volatile organic contaminants in near-real time. The strategy for air quality monitoring on SSF is designed to provide early detection so that the contamination can be confined to one module and so that crew health and safety can be protected throughout the contingency event. The use of air-quality monitors in fixed and portable modes will be presented as a means of following the progress of decontamination efforts and ensuring acceptable air quality in a module after an incident. The technology of each instrument will be reviewed briefly; the main focus of this paper, however, will be the use of air-quality monitors before, during, and after contingency incidents.

Beagle to the Moon: An Experiment Package to Measure Polar Ice and Volatiles in Permanently Shadowed Areas or Beneath the Lunar Surface

NASA Technical Reports Server (NTRS)

Gibson, E. K.; McKay, D. S.; Pillinger, C. T.; Wright, I. P.; Sims, M. R.; Richter, L.

2007-01-01

Near the beginning of the next decade we will see the launch of scientific payloads to the lunar surface to begin laying the foundations for the return to the moon in the Vision for Space Exploration. Shortly thereafter, astronauts will return to the lunar surface and have the ability to place scientific packages on the surface that will provide information about lunar resources and compositions of materials in permanently shadowed regions of the moon (1). One of the important questions which must be answered early in the program is whether there are lunar resources which would facilitate "living off the land" and not require the transport of resources and consumables from Earth (2). The Beagle science package is the ideal payload (3) to use on the lunar surface for determining the nature of hydrogen, water and lunar volatiles found in the polar regions which could support the Vision for Space Exploration

Testing the Hole-in-the-Pipe Model of nitric and nitrous oxide emissions from soils using the TRAGNET Database

NASA Astrophysics Data System (ADS)

Davidson, Eric A.; Verchot, Louis V.

2000-12-01

Because several soil properties and processes affect emissions of nitric oxide (NO) and nitrous oxide (N2O) from soils, it has been difficult to develop effective and robust algorithms to predict emissions of these gases in biogeochemical models. The conceptual "hole-in-the-pipe" (HIP) model has been used effectively to interpret results of numerous studies, but the ranges of climatic conditions and soil properties are often relatively narrow for each individual study. The Trace Gas Network (TRAGNET) database offers a unique opportunity to test the validity of one manifestation of the HIP model across a broad range of sites, including temperate and tropical climates, grasslands and forests, and native vegetation and agricultural crops. The logarithm of the sum of NO + N2O emissions was positively and significantly correlated with the logarithm of the sum of extractable soil NH4+ + NO3-. The logarithm of the ratio of NO:N2O emissions was negatively and significantly correlated with water-filled pore space (WFPS). These analyses confirm the applicability of the HIP model concept, that indices of soil N availability correlate with the sum of NO+N2O emissions, while soil water content is a strong and robust controller of the ratio of NO:N2O emissions. However, these parameterizations have only broad-brush accuracy because of unaccounted variation among studies in the soil depths where gas production occurs, where soil N and water are measured, and other factors. Although accurate predictions at individual sites may still require site-specific parameterization of these empirical functions, the parameterizations presented here, particularly the one for WFPS, may be appropriate for global biogeochemical modeling. Moreover, this integration of data sets demonstrates the broad ranging applicability of the HIP conceptual approach for understanding soil emissions of NO and N2O.

Extraction of phase information in daily stock prices

NASA Astrophysics Data System (ADS)

Fujiwara, Yoshi; Maekawa, Satoshi

2000-06-01

It is known that, in an intermediate time-scale such as days, stock market fluctuations possess several statistical properties that are common to different markets. Namely, logarithmic returns of an asset price have (i) truncated Pareto-Lévy distribution, (ii) vanishing linear correlation, (iii) volatility clustering and its power-law autocorrelation. The fact (ii) is a consequence of nonexistence of arbitragers with simple strategies, but this does not mean statistical independence of market fluctuations. Little attention has been paid to temporal structure of higher-order statistics, although it contains some important information on market dynamics. We applied a signal separation technique, called Independent Component Analysis (ICA), to actual data of daily stock prices in Tokyo and New York Stock Exchange (TSE/NYSE). ICA does a linear transformation of lag vectors from time-series to find independent components by a nonlinear algorithm. We obtained a similar impulse response for these dataset. If it were a Martingale process, it can be shown that impulse response should be a delta-function under a few conditions that could be numerically checked and as was verified by surrogate data. This result would provide information on the market dynamics including speculative bubbles and arbitrating processes. .

Ferroelectric domain switching dynamics and memristive behaviors in BiFeO3-based magnetoelectric heterojunctions

NASA Astrophysics Data System (ADS)

Huang, Weichuan; Liu, Yukuai; Luo, Zhen; Hou, Chuangming; Zhao, Wenbo; Yin, Yuewei; Li, Xiaoguang

2018-06-01

The ferroelectric domain reversal dynamics and the corresponding resistance switching as well as the memristive behaviors in epitaxial BiFeO3 (BFO, ~150 nm) based multiferroic heterojunctions were systematically investigated. The ferroelectric domain reversal dynamics could be described by the nucleation-limited-switching model with the Lorentzian distribution of logarithmic domain-switching times. By engineering the domain states, multi and even continuously tunable resistances states, i.e. memristive states, could be non-volatilely achieved. The resistance switching speed can be as fast as 30 ns in the BFO-based multiferroic heterojunctions with a write voltage of ~20 V. By reducing the thickness of BFO, the La0.6Sr0.4MnO3/BFO (~5 nm)/La0.6Sr0.4MnO3 multiferroic tunnel junction (MFTJ) shows an even a quicker switching speed (20 ns) with a much lower operation voltage (~4 V). Importantly, the MFTJ exhibits a tunable interfacial magnetoelectric coupling related to the ferroelectric domain switching dynamics. These findings enrich the potential applications of multiferroic BFO based devices in high-speed, low-power, and high-density memories as well as future neuromorphic computational architectures.

Advantages of using a logarithmic scale in pressure-volume diagrams for Carnot and other heat engine cycles

NASA Astrophysics Data System (ADS)

Shieh, Lih-Yir; Kan, Hung-Chih

2014-04-01

We demonstrate that plotting the P-V diagram of an ideal gas Carnot cycle on a logarithmic scale results in a more intuitive approach for deriving the final form of the efficiency equation. The same approach also facilitates the derivation of the efficiency of other thermodynamic engines that employ adiabatic ideal gas processes, such as the Brayton cycle, the Otto cycle, and the Diesel engine. We finally demonstrate that logarithmic plots of isothermal and adiabatic processes help with visualization in approximating an arbitrary process in terms of an infinite number of Carnot cycles.

Prediction of Soil pH Hyperspectral Spectrum in Guanzhong Area of Shaanxi Province Based on PLS

NASA Astrophysics Data System (ADS)

Liu, Jinbao; Zhang, Yang; Wang, Huanyuan; Cheng, Jie; Tong, Wei; Wei, Jing

2017-12-01

The soil pH of Fufeng County, Yangling County and Wugong County in Shaanxi Province was studied. The spectral reflectance was measured by ASD Field Spec HR portable terrain spectrum, and its spectral characteristics were analyzed. The first deviation of the original spectral reflectance of the soil, the second deviation, the logarithm of the reciprocal logarithm, the first order differential of the reciprocal logarithm and the second order differential of the reciprocal logarithm were used to establish the soil pH Spectral prediction model. The results showed that the correlation between the reflectance spectra after SNV pre-treatment and the soil pH was significantly improved. The optimal prediction model of soil pH established by partial least squares method was a prediction model based on the first order differential of the reciprocal logarithm of spectral reflectance. The principal component factor was 10, the decision coefficient Rc2 = 0.9959, the model root means square error RMSEC = 0.0076, the correction deviation SEC = 0.0077; the verification decision coefficient Rv2 = 0.9893, the predicted root mean square error RMSEP = 0.0157, The deviation of SEP = 0.0160, the model was stable, the fitting ability and the prediction ability were high, and the soil pH can be measured quickly.

Using History to Teach Mathematics: The Case of Logarithms

NASA Astrophysics Data System (ADS)

Panagiotou, Evangelos N.

2011-01-01

Many authors have discussed the question why we should use the history of mathematics to mathematics education. For example, Fauvel (For Learn Math, 11(2): 3-6, 1991) mentions at least fifteen arguments for applying the history of mathematics in teaching and learning mathematics. Knowing how to introduce history into mathematics lessons is a more difficult step. We found, however, that only a limited number of articles contain instructions on how to use the material, as opposed to numerous general articles suggesting the use of the history of mathematics as a didactical tool. The present article focuses on converting the history of logarithms into material appropriate for teaching students of 11th grade, without any knowledge of calculus. History uncovers that logarithms were invented prior of the exponential function and shows that the logarithms are not an arbitrary product, as is the case when we leap straight in the definition given in all modern textbooks, but they are a response to a problem. We describe step by step the historical evolution of the concept, in a way appropriate for use in class, until the definition of the logarithm as area under the hyperbola. Next, we present the formal development of the theory and define the exponential function. The teaching sequence has been successfully undertaken in two high school classrooms.

Are Some Fungal Volatile Organic Compounds (VOCs) Mycotoxins?

PubMed Central

Bennett, Joan W.; Inamdar, Arati A.

2015-01-01

Volatile organic compounds (VOCs) are carbon-compounds that easily evaporate at room temperature. Toxins are biologically produced poisons; mycotoxins are those toxins produced by microscopic fungi. All fungi emit blends of VOCs; the qualitative and quantitative composition of these volatile blends varies with the species of fungus and the environmental situation in which the fungus is grown. These fungal VOCs, produced as mixtures of alcohols, aldehydes, acids, ethers, esters, ketones, terpenes, thiols and their derivatives, are responsible for the characteristic moldy odors associated with damp indoor spaces. There is increasing experimental evidence that some of these VOCs have toxic properties. Laboratory tests in mammalian tissue culture and Drosophila melanogaster have shown that many single VOCs, as well as mixtures of VOCs emitted by growing fungi, have toxic effects. This paper describes the pros and cons of categorizing toxigenic fungal VOCs as mycotoxins, uses genomic data to expand on the definition of mycotoxin, and summarizes some of the linguistic and other conventions that can create barriers to communication between the scientists who study VOCs and those who study toxins. We propose that “volatoxin” might be a useful term to describe biogenic volatile compounds with toxigenic properties. PMID:26402705

LAVA subsystem integration and testing for the Resolve payload of the Resource Prospector mission: mass spectrometers and gas chromatography

NASA Astrophysics Data System (ADS)

Stewart, Elaine M.; Coan, Mary R.; Captain, Janine; Santiago-Bond, Josephine

2016-09-01

In-Situ Resource Utilization (ISRU) is a key NASA initiative to exploit resources at the site of planetary exploration for mission-critical consumables, propellants, and other supplies. The Resource Prospector mission, part of ISRU, is scheduled to launch in 2020 and will include a rover and lander hosting the Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE) payload for extracting and analyzing lunar resources, particularly low molecular weight volatiles for fuel, air, and water. RESOLVE contains the Lunar Advanced Volatile Analysis (LAVA) subsystem with a Gas Chromatograph-Mass Spectrometer (GC-MS). RESOLVE subsystems, including the RP15 rover and LAVA, are in NASA's Engineering Test Unit (ETU) phase to assure that all vital components of the payload are space-flight rated and will perform as expected during the mission. Integration and testing of LAVA mass spectrometry verified reproducibility and accuracy of the candidate MS for detecting nitrogen, oxygen, and carbon dioxide. The RP15 testing comprised volatile analysis of water-doped simulant regolith to enhance integration of the RESOLVE payload with the rover. Multiple tests show the efficacy of the GC to detect 2% and 5% water-doped samples.

VISTA: A μ-Thermogravimeter for Investigation of Volatile Compounds in Planetary Environments.

PubMed

Palomba, Ernesto; Longobardo, Andrea; Dirri, Fabrizio; Zampetti, Emiliano; Biondi, David; Saggin, Bortolino; Bearzotti, Andrea; Macagnano, Antonella

2016-06-01

This paper presents the VISTA (Volatile In Situ Thermogravimetry Analyser) instrument, conceived to perform planetary in-situ measurements. VISTA can detect and quantify the presence of volatile compounds of astrobiological interest, such as water and organics, in planetary samples. These measurements can be particularly relevant when performed on primitive asteroids or comets, or on targets of potential astrobiological interest such as Mars or Jupiter's satellite Europa. VISTA is based on a micro-thermogravimetry technique, widely used in different environments to study absorption and sublimation processes. The instrument core is a piezoelectric crystal microbalance, whose frequency variations are affected by variations of the mass of the deposited sample, due to chemical processes such as sublimation, condensation or absorption/desorption. The low mass (i.e. 40 g), the low volume (less than 10 cm(3)) and the low power (less than 1 W) required makes this kind of instrument very suitable for space missions. This paper discusses the planetary applications of VISTA, and shows the calibration operations performed on the breadboard, as well as the performance tests which demonstrate the capability of the breadboard to characterize volatile compounds of planetary interests.

A general number-to-space mapping deficit in developmental dyscalculia.

PubMed

Huber, S; Sury, D; Moeller, K; Rubinsten, O; Nuerk, H-C

2015-01-01

Previous research on developmental dyscalculia (DD) suggested that deficits in the number line estimation task are related to a failure to represent number magnitude linearly. This conclusion was derived from the observation of logarithmically shaped estimation patterns. However, recent research questioned this idea of an isomorphic relationship between estimation patterns and number magnitude representation. In the present study, we evaluated an alternative hypothesis: impairments in the number line estimation task are due to a general deficit in mapping numbers onto space. Adults with DD and a matched control group had to learn linear and non-linear layouts of the number line via feedback. Afterwards, we assessed their performance how well they learnt the new number-space mappings. We found irrespective of the layouts worse performance of adults with DD. Additionally, in case of the linear layout, we observed that their performance did not differ from controls near reference points, but that differences between groups increased as the distance to reference point increased. We conclude that worse performance of adults with DD in the number line task might be due a deficit in mapping numbers onto space which can be partly overcome relying on reference points. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mercury's Weather-Beaten Surface: Understanding Mercury in the Context of Lunar and Asteroidal Space Weathering Studies

NASA Technical Reports Server (NTRS)

Domingue, Deborah L.; Chapman, Clark. R.; Killen, Rosemary M.; Zurbuchen, Thomas H.; Gilbert, Jason A.; Sarantos, Menelaos; Benna, Mehdi; Slavin, James A.; Schriver, David; Travnicek, Pavel M.;

Lunar Flashlight: Mapping Lunar Surface Volatiles Using a Cubesat

NASA Technical Reports Server (NTRS)

Cohen, B. A.; Hayne, P. O.; Banazadeh, P.; Baker, J. D.; Staehle, R. L.; Paine, C..; Paige, D. A.

2014-01-01

Water ice and other volatiles may be located in the Moon's polar regions, with sufficient quantities for in situ extraction and utilization by future human and robotic missions. Evidence from orbiting spacecraft and the LCROSS impactor suggests the presence of surface and/or nearsurface volatiles, including water ice. These deposits are of interest to human exploration to understand their potential for use by astronauts. Understanding the composition, quantity, distribution, and form of water/H species and other volatiles associated with lunar cold traps is identified as a NASA Strategic Knowledge Gap (SKG) for Human Exploration. These polar volatile deposits could also reveal important information about the delivery of water to the Earth- Moon system, so are of scientific interest. The scientific exploration of the lunar polar regions was one of the key recommendations of the Planetary Science Decadal Survey. In order to address NASA's SKGs, the Advanced Exploration Systems (AES) program selected three lowcost 6-U CubeSat missions for launch as secondary payloads on the first test flight (EM1) of the Space Launch System (SLS) scheduled for 2017. The Lunar Flashlight mission was selected as one of these missions, specifically to address the SKG associated with lunar volatiles. Development of the Lunar Flashlight CubeSat concept leverages JPL's Interplanetary Nano- Spacecraft Pathfinder In Relevant Environment (INSPIRE) mission, MSFC's intimate knowledge of the Space Launch System and EM-1 mission, small business development of solar sail and electric propulsion hardware, and JPL experience with specialized miniature sensors. The goal of Lunar Flashlight is to determine the presence or absence of exposed water ice and its physical state, and map its concentration at the kilometer scale within the permanently shadowed regions of the lunar south pole. After being ejected in cislunar space by SLS, Lunar Flashlight deploys its solar panels and solar sail and maneuvers into a low-energy transfer to lunar orbit. The solar sail and attitude control system work to bring the satellite into an elliptical polar orbit spiraling down to a perilune of 30-10 km above the south pole for data collection. Lunar Flashlight uses its solar sail to shine reflected sunlight into permanently shadowed regions, measuring surface albedo with a four-filter point spectrometer at 1.1, 1.5 1.9, and 2.0 microns. Water ice will be distinguished from dry regolith from these measurements in two ways: 1) spatial variations in absolute reflectance (water ice is much brighter in the continuum channels), and 2) reflectance ratios between absorption and continuum channels. Derived reflectance and reflectance ratios will be mapped onto the lunar surface in order to distinguish the composition of the PSRs from that of the sunlit terrain. Lunar Flashlight enables a low-cost path to in-situ resource utilization (ISRU) by identifying operationally useful deposits (if there are any), which is a game-changing capability for expanded human exploration.

Size-dependent standard deviation for growth rates: Empirical results and theoretical modeling

NASA Astrophysics Data System (ADS)

Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H. Eugene; Grosse, I.

2008-05-01

We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation σ(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation σ(R) on the average value of the wages with a scaling exponent β≈0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation σ(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of σ(R) on the average payroll with a scaling exponent β≈-0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

Size-dependent standard deviation for growth rates: empirical results and theoretical modeling.

PubMed

Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H Eugene; Grosse, I

2008-05-01

We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation sigma(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation sigma(R) on the average value of the wages with a scaling exponent beta approximately 0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation sigma(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of sigma(R) on the average payroll with a scaling exponent beta approximately -0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

Internationalization for an Uncertain Future: Tensions, Paradoxes, and Possibilities

ERIC Educational Resources Information Center

Stein, Sharon

2017-01-01

As higher education is increasingly called upon to play a central role in addressing the challenges and crises of today's complex, uncertain, and volatile world, internationalization efforts are intensifying. Emphasizing higher education as a space for critically-informed, socially accountable, and open-ended conversations about alternative…

Resumming double logarithms in the QCD evolution of color dipoles

DOE PAGES

Iancu, E.; Madrigal, J. D.; Mueller, A. H.; ...

2015-05-01

The higher-order perturbative corrections, beyond leading logarithmic accuracy, to the BFKL evolution in QCD at high energy are well known to suffer from a severe lack-of-convergence problem, due to radiative corrections enhanced by double collinear logarithms. Via an explicit calculation of Feynman graphs in light cone (time-ordered) perturbation theory, we show that the corrections enhanced by double logarithms (either energy-collinear, or double collinear) are associated with soft gluon emissions which are strictly ordered in lifetime. These corrections can be resummed to all orders by solving an evolution equation which is non-local in rapidity. This equation can be equivalently rewritten inmore » local form, but with modified kernel and initial conditions, which resum double collinear logs to all orders. We extend this resummation to the next-to-leading order BFKL and BK equations. The first numerical studies of the collinearly-improved BK equation demonstrate the essential role of the resummation in both stabilizing and slowing down the evolution.« less

Coulomb Logarithm in Nonideal and Degenerate Plasmas

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Starostin, A. N.; Gryaznov, V. K.

2018-03-01

Various methods for determining the Coulomb logarithm in the kinetic theory of transport and various variants of the choice of the plasma screening constant, taking into account and disregarding the contribution of the ion component and the boundary value of the electron wavevector are considered. The correlation of ions is taken into account using the Ornstein-Zernike integral equation in the hypernetted-chain approximation. It is found that the effect of ion correlation in a nondegenerate plasma is weak, while in a degenerate plasma, this effect must be taken into account when screening is determined by the electron component alone. The calculated values of the electrical conductivity of a hydrogen plasma are compared with the values determined experimentally in the megabar pressure range. It is shown that the values of the Coulomb logarithm can indeed be smaller than unity. Special experiments are proposed for a more exact determination of the Coulomb logarithm in a magnetic field for extremely high pressures, for which electron scattering by ions prevails.

The energy distribution of subjets and the jet shape

DOE PAGES

Kang, Zhong-Bo; Ringer, Felix; Waalewijn, Wouter J.

2017-07-13

We present a framework that describes the energy distribution of subjets of radius r within a jet of radius R. We consider both an inclusive sample of subjets as well as subjets centered around a predetermined axis, from which the jet shape can be obtained. For r << R we factorize the physics at angular scales r and R to resum the logarithms of r/R. For central subjets, we consider both the standard jet axis and the winner-take-all axis, which involve double and single logarithms of r/R, respectively. All relevant one-loop matching coefficients are given, and an inconsistency in somemore » previous results for cone jets is resolved. Our results for the standard jet shape differ from previous calculations at next-to-leading logarithmic order, because we account for the recoil of the standard jet axis due to soft radiation. Numerical results are presented for an inclusive subjet sample for pp → jet + X at next-to-leading order plus leading logarithmic order.« less

Logarithmic Laplacian Prior Based Bayesian Inverse Synthetic Aperture Radar Imaging.

PubMed

Zhang, Shuanghui; Liu, Yongxiang; Li, Xiang; Bi, Guoan

2016-04-28

This paper presents a novel Inverse Synthetic Aperture Radar Imaging (ISAR) algorithm based on a new sparse prior, known as the logarithmic Laplacian prior. The newly proposed logarithmic Laplacian prior has a narrower main lobe with higher tail values than the Laplacian prior, which helps to achieve performance improvement on sparse representation. The logarithmic Laplacian prior is used for ISAR imaging within the Bayesian framework to achieve better focused radar image. In the proposed method of ISAR imaging, the phase errors are jointly estimated based on the minimum entropy criterion to accomplish autofocusing. The maximum a posterior (MAP) estimation and the maximum likelihood estimation (MLE) are utilized to estimate the model parameters to avoid manually tuning process. Additionally, the fast Fourier Transform (FFT) and Hadamard product are used to minimize the required computational efficiency. Experimental results based on both simulated and measured data validate that the proposed algorithm outperforms the traditional sparse ISAR imaging algorithms in terms of resolution improvement and noise suppression.

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

Kang, Zhong-Bo; Ringer, Felix; Waalewijn, Wouter J.

We present a framework that describes the energy distribution of subjets of radius r within a jet of radius R. We consider both an inclusive sample of subjets as well as subjets centered around a predetermined axis, from which the jet shape can be obtained. For r << R we factorize the physics at angular scales r and R to resum the logarithms of r/R. For central subjets, we consider both the standard jet axis and the winner-take-all axis, which involve double and single logarithms of r/R, respectively. All relevant one-loop matching coefficients are given, and an inconsistency in somemore » previous results for cone jets is resolved. Our results for the standard jet shape differ from previous calculations at next-to-leading logarithmic order, because we account for the recoil of the standard jet axis due to soft radiation. Numerical results are presented for an inclusive subjet sample for pp → jet + X at next-to-leading order plus leading logarithmic order.« less

KENNEDY SPACE CENTER, FLA. -- In the Space Life Sciences Lab, Lanfang Levine, with Dynamac Corp., transfers material into a sample bottle for analysis. She is standing in front of new equipment in the lab that will provide gas chromatography and mass spectrometry. The equipment will enable analysis of volatile compounds, such as from plants. The 100,000 square-foot facility houses labs for NASA’s ongoing research efforts, microbiology/microbial ecology studies and analytical chemistry labs. Also calling the new lab home are facilities for space flight-experiment and flight-hardware development, new plant growth chambers, and an Orbiter Environment Simulator that will be used to conduct ground control experiments in simulated flight conditions for space flight experiments. The SLS Lab, formerly known as the Space Experiment Research and Processing Laboratory or SERPL, provides space for NASA’s Life Sciences Services contractor Dynamac Corporation, Bionetics Corporation, and researchers from the University of Florida. NASA’s Office of Biological and Physical Research will use the facility for processing life sciences experiments that will be conducted on the International Space Station. The SLS Lab is the magnet facility for the International Space Research Park at KSC being developed in partnership with Florida Space Authority.

NASA Image and Video Library

2004-01-05

KENNEDY SPACE CENTER, FLA. -- In the Space Life Sciences Lab, Lanfang Levine, with Dynamac Corp., transfers material into a sample bottle for analysis. She is standing in front of new equipment in the lab that will provide gas chromatography and mass spectrometry. The equipment will enable analysis of volatile compounds, such as from plants. The 100,000 square-foot facility houses labs for NASA’s ongoing research efforts, microbiology/microbial ecology studies and analytical chemistry labs. Also calling the new lab home are facilities for space flight-experiment and flight-hardware development, new plant growth chambers, and an Orbiter Environment Simulator that will be used to conduct ground control experiments in simulated flight conditions for space flight experiments. The SLS Lab, formerly known as the Space Experiment Research and Processing Laboratory or SERPL, provides space for NASA’s Life Sciences Services contractor Dynamac Corporation, Bionetics Corporation, and researchers from the University of Florida. NASA’s Office of Biological and Physical Research will use the facility for processing life sciences experiments that will be conducted on the International Space Station. The SLS Lab is the magnet facility for the International Space Research Park at KSC being developed in partnership with Florida Space Authority.

Nonlinear coherent optical image processing using logarithmic transmittance of bacteriorhodopsin films

NASA Astrophysics Data System (ADS)

Downie, John D.

1995-08-01

The transmission properties of some bacteriorhodopsin-film spatial light modulators are uniquely suited to allow nonlinear optical image-processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude-transmission characteristic of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. I present experimental results demonstrating the principle and the capability for several different image and noise situations, including deterministic noise and speckle. The bacteriorhodopsin film studied here displays the logarithmic transmission response for write intensities spanning a dynamic range greater than 2 orders of magnitude.

Next-to-leading order Balitsky-Kovchegov equation with resummation

DOE PAGES

Lappi, T.; Mantysaari, H.

2016-05-03

Here, we solve the Balitsky-Kovchegov evolution equation at next-to-leading order accuracy including a resummation of large single and double transverse momentum logarithms to all orders. We numerically determine an optimal value for the constant under the large transverse momentum logarithm that enables including a maximal amount of the full NLO result in the resummation. When this value is used, the contribution from the α 2 s terms without large logarithms is found to be small at large saturation scales and at small dipoles. Close to initial conditions relevant for phenomenological applications, these fixed-order corrections are shown to be numerically important.

Nonlinear Coherent Optical Image Processing Using Logarithmic Transmittance of Bacteriorhodopsin Films

NASA Technical Reports Server (NTRS)

Downie, John D.

1995-01-01

The transmission properties of some bacteriorhodopsin-film spatial light modulators are uniquely suited to allow nonlinear optical image-processing operations to be applied to images with multiplicative noise characteristics. A logarithmic amplitude-transmission characteristic of the film permits the conversion of multiplicative noise to additive noise, which may then be linearly filtered out in the Fourier plane of the transformed image. I present experimental results demonstrating the principle and the capability for several different image and noise situations, including deterministic noise and speckle. The bacteriorhodopsin film studied here displays the logarithmic transmission response for write intensities spanning a dynamic range greater than 2 orders of magnitude.

LOGARITHMIC AMPLIFIER

DOEpatents

Wade, E.J.; Stone, R.S.

1959-03-10

Electronic,amplifier circuits, especially a logai-ithmic amplifier characterizxed by its greatly improved strability are discussed. According to the in ention, means are provided to feed bach the output valtagee to a diode in the amplifier input circuit, the diode being utilized to produce the logarithmic characteristics. The diode is tics, The diode isition therewith and having its filament operated from thc same source s the filament of the logarithmic diode. A bias current of relatively large value compareii with the signal current is continuously passed through the compiting dioie to render the diode insensitivy to variations in the signal current. by this odes kdu to variaelled, so that the stability of the amlifier will be unimpaired.

Inorganic composites for space applications

NASA Technical Reports Server (NTRS)

Malmendier, J. W.

1984-01-01

The development of inorganic composite materials for space applications is reviewed. The composites do not contain any organic materials, and therefore, are not subject to degradation by ultraviolet radiation, volatilization of constituents, or embrittlement at low temperatures. The composites consist of glass, glass/ceramics or ceramic matrices, reinforced by refractory whiskers or fibers. Such composites have the low thermal expansion, refractories, chemical stability and other desirable properties usually associated with the matrix materials. The composites also have a degree of toughness which is extraordinary for refractory inorganic materials.

KSC-2013-3992

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on agency programs by Lindsay Hays, an astrobiologist at NASA Headquarters. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3991

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on the agency's CubeSat Program by Andrew Petro, small satellites program manager. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

KSC-2013-3989

NASA Image and Video Library

2013-11-16

CAPE CANAVERAL, Fla. -- In the conference room of Operations Support Building II at NASA's Kennedy Space Center in Florida, social media participants listen to a briefing on future agency programs by Billy Stover, a NASA Commercial Crew Program Safety engineer. The social media participants gathered at the Florida spaceport for the launch of the Mars Atmosphere and Volatile Evolution, or MAVEN, spacecraft. Their visit included tours of key facilities and participating in presentations by key NASA leaders who updated the space agency's current efforts. Photo credit: NASA/Jim Grossman

Shuttle Lesson Learned - Toxicology

NASA Technical Reports Server (NTRS)

James, John T.

2010-01-01

This is a script for a video about toxicology and the space shuttle. The first segment is deals with dust in the space vehicle. The next segment will be about archival samples. Then we'll look at real time on-board analyzers that give us a lot of capability in terms of monitoring for combustion products and the ability to monitor volatile organics on the station. Finally we will look at other issues that are about setting limits and dealing with ground based lessons that pertain to toxicology.

Origin of organic matter in the protosolar nebula and in comets

NASA Technical Reports Server (NTRS)

Greenberg, J. M.; Shalabiea, O. M.; Mendoza-Gomez, C. X.; Schutte, W.; Gerakines, P. A.

1994-01-01

Comet organics are traced to their origin in interstellar space. Possible sources of comet organics from solar nebula chemistry are briefly discussed. The infrared spectra of interstellar dust are compared with spectra of solar (space) irradiated laboratory organic residues and with meteorites. The spectra compare very favorably. The atomic composition of first generation laboratory organic residues compares favorably with that of comet Halley organics if divided into approrpriate 'volatile' (less refreactory) and 'refractory' (more refractory) complex organics.

Membrane Inlet Mass Spectrometry for Homeland Security and Forensic Applications

NASA Astrophysics Data System (ADS)

Giannoukos, Stamatios; Brkić, Boris; Taylor, Stephen; France, Neil

2015-02-01

A man-portable membrane inlet mass spectrometer has been built and tested to detect and monitor characteristic odors emitted from the human body and also from threat substances. In each case, a heated membrane sampling probe was used. During human scent monitoring experiments, data were obtained for inorganic gases and volatile organic compounds emitted from human breath and sweat in a confined space. Volatile emissions were detected from the human body at low ppb concentrations. Experiments with compounds associated with narcotics, explosives, and chemical warfare agents were conducted for a range of membrane types. Test compounds included methyl benzoate (odor signature of cocaine), piperidine (precursor in clandestine phencyclidine manufacturing processes), 2-nitrotoluene (breakdown product of TNT), cyclohexanone (volatile signature of plastic explosives), dimethyl methylphosphonate (used in sarin and soman nerve agent production), and 2-chloroethyl ethyl sulfide (simulant compound for sulfur mustard gas). Gas phase calibration experiments were performed allowing sub-ppb LOD to be established. The results showed excellent linearity versus concentration and rapid membrane response times.

Membrane inlet mass spectrometry for homeland security and forensic applications.

PubMed

Giannoukos, Stamatios; Brkić, Boris; Taylor, Stephen; France, Neil

2015-02-01

A man-portable membrane inlet mass spectrometer has been built and tested to detect and monitor characteristic odors emitted from the human body and also from threat substances. In each case, a heated membrane sampling probe was used. During human scent monitoring experiments, data were obtained for inorganic gases and volatile organic compounds emitted from human breath and sweat in a confined space. Volatile emissions were detected from the human body at low ppb concentrations. Experiments with compounds associated with narcotics, explosives, and chemical warfare agents were conducted for a range of membrane types. Test compounds included methyl benzoate (odor signature of cocaine), piperidine (precursor in clandestine phencyclidine manufacturing processes), 2-nitrotoluene (breakdown product of TNT), cyclohexanone (volatile signature of plastic explosives), dimethyl methylphosphonate (used in sarin and soman nerve agent production), and 2-chloroethyl ethyl sulfide (simulant compound for sulfur mustard gas). Gas phase calibration experiments were performed allowing sub-ppb LOD to be established. The results showed excellent linearity versus concentration and rapid membrane response times.

A Water Recovery System Evolved for Exploration

NASA Technical Reports Server (NTRS)

ORourke, Mary Jane E.; Perry, Jay L.; Carter, Donald L.

2006-01-01

A new water recovery system designed towards fulfillment of NASA's Vision for Space Exploration is presented. This water recovery system is an evolution of the current state-of-the-art system. Through novel integration of proven technologies for air and water purification, this system promises to elevate existing technology to higher levels of optimization. The novel aspect of the system is twofold: Volatile organic contaminants will be removed from the cabin air via catalytic oxidation in the vapor phase, prior to their absorption into the aqueous phase, and vapor compression distillation technology will be used to process the condensate and hygiene waste streams in addition to the urine waste stream. Oxidation kinetics dictate that removal of volatile organic contaminants from the vapor phase is more efficient. Treatment of the various waste streams by VCD will reduce the load on the expendable ion exchange and adsorption media which follow, and on the aqueous-phase volatile removal assembly further downstream. Incorporating these advantages will reduce the weight, volume, and power requirements of the system, as well as resupply.

Configuration of Pluto's Volatile Ices

NASA Astrophysics Data System (ADS)

Grundy, William M.; Binzel, R. P.; Cook, J. C.; Cruikshank, D. P.; Dalle Ore, C. M.; Earle, A. M.; Ennico, K.; Jennings, D. E.; Howett, C. J. A.; Linscott, I. R.; Lunsford, A. W.; Olkin, C. B.; Parker, A. H.; Parker, J. Wm; Protopapa, S.; Reuter, D. C.; Singer, K. N.; Spencer, J. R.; Stern, S. A.; Tsang, C. C. C.; Verbiscer, A. J.; Weaver, H. A.; Young, L. A.; Berry, K.; Buie, M. W.; Stansberry, J. A.

2015-11-01

We report on near-infrared remote sensing by New Horizons' Ralph instrument (Reuter et al. 2008, Space Sci. Rev. 140, 129-154) of Pluto's N2, CO, and CH4 ices. These especially volatile ices are mobile even at Pluto's cryogenic surface temperatures. Sunlight reflected from these ices becomes imprinted with their characteristic spectral absorption bands. The detailed appearance of these absorption features depends on many aspects of local composition, thermodynamic state, and texture. Multiple-scattering radiative transfer models are used to retrieve quantitative information about these properties and to map how they vary across Pluto's surface. Using parameter maps derived from New Horizons observations, we investigate the striking regional differences in the abundances and scattering properties of Pluto's volatile ices. Comparing these spatial patterns with the underlying geology provides valuable constraints on processes actively modifying the planet's surface, over a variety of spatial scales ranging from global latitudinal patterns to more regional and local processes within and around the feature informally known as Sputnik Planum. This work was supported by the NASA New Horizons Project.

Strong catalytic activity of iron nanoparticles on the surfaces of reduced olivine

NASA Astrophysics Data System (ADS)

Tucker, William C.; Quadery, Abrar H.; Schulte, Alfons; Blair, Richard G.; Kaden, William E.; Schelling, Patrick K.; Britt, Daniel T.

2018-01-01

It is demonstrated that olivine powders heated to subsolidus temperatures in reducing conditions can develop significant concentrations of 10-50 nm diameter Fe nanoparticles on grain surfaces and that these display strong catalytic activity not observed in powders without Fe nanoparticles. Reduced surfaces were exposed to NH3, CO, and H2, volatiles that may be present on the surfaces of comet and volatile-rich asteroids. In the case of NH3 exposure, rapid decomposition was observed. When exposed to a mixture of CO and H2, significant coking of the mineral surfaces occurred. Analysis of the mineral grains after reaction indicated primarily the presence of graphene or graphitic carbon. The results demonstrate that strong chemical activity can be expected at powders that contain nanophase Fe particles. This suggests space-weathered mineral surfaces may play an important role in the synthesis and processing of organic species. This processing may be part of the weathering processes of volatile-rich but atmosphereless solar-system bodies.

Chemical mimicry of insect oviposition sites: a global analysis of convergence in angiosperms.

PubMed

Jürgens, Andreas; Wee, Suk-Ling; Shuttleworth, Adam; Johnson, Steven D

2013-09-01

Floral mimicry of decaying plant or animal material has evolved in many plant lineages and exploits, for the purpose of pollination, insects seeking oviposition sites. Existing studies suggest that volatile signals play a particularly important role in these mimicry systems. Here, we present the first large-scale phylogenetically informed study of patterns of evolution in the volatile emissions of plants that mimic insect oviposition sites. Multivariate analyses showed strong convergent evolution, represented by distinct clusters in chemical phenotype space of plants that mimic animal carrion, decaying plant material, herbivore dung and omnivore/carnivore faeces respectively. These plants deploy universal infochemicals that serve as indicators for the main nutrients utilised by saprophagous, coprophagous and necrophagous insects. The emission of oligosulphide-dominated volatile blends very similar to those emitted by carrion has evolved independently in at least five plant families (Annonaceae, Apocynaceae, Araceae, Orchidaceae and Rafflesiaceae) and characterises plants associated mainly with pollination by necrophagous flies and beetles. © 2013 John Wiley & Sons Ltd/CNRS.

MACRO- MICRO-PURGE SOIL GAS SAMPLING METHODS FOR THE COLLECTION OF CONTAMINANT VAPORS

EPA Science Inventory

Purging influence on soil gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., dead-space purge volume), was evaluated at different field sites. A macro-purge sampling system consisted of a standard hollo...

The Nature of Mercury's Hollows, and Space Weathering Close to the Sun

NASA Astrophysics Data System (ADS)

Blewett, D. T.; Chabot, N. L.; Denevi, B. W.; Ernst, C. M.

2018-05-01

Hollows are a landform that appear to form by loss of a volatile-bearing phase from silicate rock. Hollows are very young and are likely to be forming in the present day. Hollows may be an analog for extreme weathering on near-Sun asteroids.

Generation of Volatile Organic Compounds from Dissolved Organic Matter in far North Atlantic Surface Ocean Waters.

NASA Astrophysics Data System (ADS)

Hudson, E. D.; Ariya, P. A.

2005-12-01

The photochemical degradation of dissolved organic matter (DOM) in surface ocean waters is thought to be a source of volatile organic compounds (VOC) (including non-methane hydrocarbons and low MW carbonyl compounds) to the remote marine troposphere. We report on the characterization of DOM sampled at over 30 sites in the far North Atlantic (Greenland and Norwegian seas, Fram strait) during the summer of 2004, and on experiments to identify factors responsible for the photochemical generation of VOCs in these samples. The results will be discussed in the context of VOC profiles of whole air samples taken to match the seawater samples in time and space.

Calibration of Lévy Processes with American Options

NASA Astrophysics Data System (ADS)

Achdou, Yves

We study options on financial assets whose discounted prices are exponential of Lévy processes. The price of an American vanilla option as a function of the maturity and the strike satisfies a linear complementarity problem involving a non-local partial integro-differential operator. It leads to a variational inequality in a suitable weighted Sobolev space. Calibrating the Lévy process may be done by solving an inverse least square problem where the state variable satisfies the previously mentioned variational inequality. We first assume that the volatility is positive: after carefully studying the direct problem, we propose necessary optimality conditions for the least square inverse problem. We also consider the direct problem when the volatility is zero.

First results from the Mojave Volatiles Prospector (MVP) Field Campaign, a Lunar Polar Rover Mission Analog

NASA Astrophysics Data System (ADS)

Heldmann, J. L.; Colaprete, A.; Cook, A.; Deans, M. C.; Elphic, R. C.; Lim, D. S. S.; Skok, J. R.

2014-12-01

The Mojave Volatiles Prospector (MVP) project is a science-driven field program with the goal to produce critical knowledge for conducting robotic exploration of the Moon. MVP will feed science, payload, and operational lessons learned to the development of a real-time, short-duration lunar polar volatiles prospecting mission. MVP achieves these goals through a simulated lunar rover mission to investigate the composition and distribution of surface and subsurface volatiles in a natural and a priori unknown environment within the Mojave Desert, improving our understanding of how to find, characterize, and access volatiles on the Moon. The MVP field site is the Mojave Desert, selected for its low, naturally occurring water abundance. The Mojave typically has on the order of 2-6% water, making it a suitable lunar analog for this field test. MVP uses the Near Infrared and Visible Spectrometer Subsystem (NIRVSS), Neutron Spectrometer Subsystem (NSS), and a downward facing GroundCam camera on the KREX-2 rover to investigate the relationship between the distribution of volatiles and soil crust variation. Through this investigation, we mature robotic in situ instruments and concepts of instrument operations, improve ground software tools for real time science, and carry out publishable research on the water cycle and its connection to geomorphology and mineralogy in desert environments. A lunar polar rover mission is unlike prior space missions and requires a new concept of operations. The rover must navigate 3-5 km of terrain and examine multiple sites in in just ~6 days. Operational decisions must be made in real time, requiring constant situational awareness, data analysis and rapid turnaround decision support tools. This presentation will focus on the first science results and operational architecture findings from the MVP field deployment relevant to a lunar polar rover mission.

Evaluation of the separation characteristics of application-specific (volatile organic compounds) open-tubular columns for gas chromatography.

PubMed

Poole, Colin F; Qian, Jing; Kiridena, Waruna; Dekay, Colleen; Koziol, Wladyslaw W

2006-11-17

The solvation parameter model is used to characterize the separation characteristics of two application-specific open-tubular columns (Rtx-Volatiles and Rtx-VGC) and a general purpose column for the separation of volatile organic compounds (DB-WAXetr) at five equally spaced temperatures over the range 60-140 degrees C. System constant differences and retention factor correlation plots are then used to determine selectivity differences between the above columns and their closest neighbors in a large database of system constants and retention factors for forty-four open-tubular columns. The Rtx-Volatiles column is shown to have separation characteristics predicted for a poly(dimethyldiphenylsiloxane) stationary phase containing about 16% diphenylsiloxane monomer. The Rtx-VGC column has separation properties similar to the poly(cyanopropylphenyldimethylsiloxane) stationary phase containing 14% cyanopropylphenylsiloxane monomer DB-1701 for non-polar and dipolar/polarizable compounds but significantly different characteristics for the separation of hydrogen-bond acids. For all practical purposes the DB-WAXetr column is shown to be selectivity equivalent to poly(ethylene glycol) columns prepared using different chemistries for bonding and immobilizing the stationary phase. Principal component analysis and cluster analysis are then used to classify the system constants for the above columns and a sub-database of eleven open-tubular columns (DB-1, HP-5, DB-VRX, Rtx-20, DB-35, Rtx-50, Rtx-65, DB-1301, DB-1701, DB-200, and DB-624) commonly used for the separation of volatile organic compounds. A rationale basis for column selection based on differences in intermolecular interactions is presented as an aid to method development for the separation of volatile organic compounds.

Thermo-chemical modelling of a village cookstove for design improvement

NASA Astrophysics Data System (ADS)

Honkalaskar, Vijay H.; Sohoni, Milind; Bhandarkar, Upendra V.

2014-05-01

Cookstove operation comprises three basic processes, namely combustion of firewood, natural air draft due to the buoyancy induced by the temperature difference between the hearth and its surroundings, and heat transfer to the pot, stove body and surrounding atmosphere. Owing to the heterogenous and unsteady burning of solid fuel, there exist nonlinear and dynamic interrelationships among these process parameters. A steady-state analytical model of the cookstove operation is developed for its design improvement by splitting the hearth into three zones to study char combustion, volatile combustion and heat transfer to the pot bottom separately. It comprises a total of seven relations corresponding to a thorough analysis of the three basic processes. A novel method is proposed to model the combustion of wood to mimic the realities closely. Combustion space above the fuel bed is split into 1000 discrete parts to study the combustion of volatiles by considering a set of representative volatile gases. Model results are validated by comparing them with a set of water boiling tests carried on a traditional cookstove in the laboratory. It is found that the major thrust areas to improve the thermal performance are combustion of volatiles and the heat transfer to the pot. It is revealed that the existing design dimensions of the traditional cookstove are close to their optimal values. Addition of twisted-tape inserts in the hearth of the cookstove shows an improvement in the thermal performance due to increase in the heat transfer coefficient to the pot bottom and improved combustion of volatiles.

A Monte-Carlo Analysis of Organic Volatility with Aerosol Microphysics

NASA Astrophysics Data System (ADS)

Gao, Chloe; Tsigaridis, Kostas; Bauer, Susanne E.

2017-04-01

A newly developed box model, MATRIX-VBS, includes the volatility-basis set (VBS) framework in an aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves aerosol mass and number concentrations and aerosol mixing state. The new scheme advanced the representation of organic aerosols in models by improving the traditional and simplistic treatment of organic aerosols as non-volatile and with a fixed size distribution. Further development includes adding the condensation of organics on coarse mode aerosols - dust and sea salt, thus making all organics in the system semi-volatile. To test and simplify the model, a Monte-Carlo analysis is performed to pin point which processes affect organics the most under varied chemical and meteorological conditions. Since the model's parameterizations have the ability to capture a very wide range of conditions, all possible scenarios on Earth across the whole parameter space, including temperature, humidity, location, emissions and oxidant levels, are examined. The Monte-Carlo simulations provide quantitative information on the sensitivity of the newly developed model and help us understand how organics are affecting the size distribution, mixing state and volatility distribution at varying levels of meteorological conditions and pollution levels. In addition, these simulations give information on which parameters play a critical role in the aerosol distribution and evolution in the atmosphere and which do not, that will facilitate the simplification of the box model, an important step in its implementation in the global model GISS ModelE as a module.

Comparison of glass vessels and plastic bags for enclosing living plant parts for headspace analysis.

PubMed

Stewart-Jones, Alex; Poppy, Guy M

2006-04-01

Plants release volatile chemicals into their surrounding air space that can affect the physiology of neighboring plants and influence the behavior of insects. In studying these interactions, it is desirable to collect volatiles from plants that have not been excised and are growing under as natural conditions as possible. We compared a vessel of borosilicate glass and Nylon-6 or polyester [poly(ethyleneterephthalate) or PET] cooking bags for enclosing plants during collection of volatiles. A push-pull airflow system was used, and volatiles were trapped on Tenax TA and analyzed by gas chromatography after thermal desorption. Low levels of impurities were found for the glass vessel and polyester bags. Nylon bags contained higher levels and more impurities. Recoveries of standards of 10 plant volatiles were measured in static and dynamic systems. In a static air system, there was good recovery only from the glass vessel. In a dynamic system, there was generally good recovery from both the glass vessel and polyester bags. Recoveries of alpha-pinene and (Z)-jasmone were poor throughout. The former was shown to have a very low breakthrough volume on the Tenax TA adsorbent, and the latter may be strongly adsorbed on glass. All three materials were essentially transparent in the IR and visible (photosynthetic) range but with significantly different absorptions in the UV range. In a simulated dynamic entrainment in full sunlight, internal vessel temperatures were higher than ambient by up to 9.5 degrees C in the glass vessel and 7.5 degrees C in the polyester bag. Lower increases in temperature relative to ambient (<1 degrees C) were recorded when entrainments were conducted in the shade. In a field trial, the profiles of volatiles collected from an apple tree infested with rosy apple aphid using a glass vessel and a polyester bag were similar. Polyester bags are recommended as more convenient than glass vessels for the enclosure of plants during the collection of volatiles.

Ask the Experts

ERIC Educational Resources Information Center

Science Teacher, 2005

2005-01-01

This article features questions regarding logarithmic functions and hair growth. The first question is, "What is the underlying natural phenomenon that causes the natural log function to show up so frequently in scientific equations?" There are two reasons for this. The first is simply that the logarithm of a number is often used as a replacement…

Product and Quotient Rules from Logarithmic Differentiation

ERIC Educational Resources Information Center

Chen, Zhibo

2012-01-01

A new application of logarithmic differentiation is presented, which provides an alternative elegant proof of two basic rules of differentiation: the product rule and the quotient rule. The proof can intrigue students, help promote their critical thinking and rigorous reasoning and deepen their understanding of previously encountered concepts. The…

Indoor Air Quality Assessment of the San Francisco Federal Building

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

Apte, Michael; Bennett, Deborah H.; Faulkner, David

2008-07-01

An assessment of the indoor air quality (IAQ) of the San Francisco Federal Building (SFFB) was conducted on May 12 and 14, 2009 at the request of the General Services Administration (GSA). The purpose of the assessment was for a general screening of IAQ parameters typically indicative of well functioning building systems. One naturally ventilated space and one mechanically ventilated space were studied. In both zones, the levels of indoor air contaminants, including CO2, CO, particulate matter, volatile organic compounds, and aldehydes, were low, relative to reference exposure levels and air quality standards for comparable office buildings. We found slightlymore » elevated levels of volatile organic compounds (VOCs) including two compounds often found in"green" cleaning products. In addition, we found two industrial solvents at levels higher than typically seen in office buildings, but the levels were not sufficient to be of a health concern. The ventilation rates in the two study spaces were high by any standard. Ventilation rates in the building should be further investigated and adjusted to be in line with the building design. Based on our measurements, we conclude that the IAQ is satisfactory in the zone we tested, but IAQ may need to be re-checked after the ventilation rates have been lowered.« less

Controls on the organization of the plumbing system of subduction volcanoes : the roles of volatiles and edifice load

NASA Astrophysics Data System (ADS)

Roman, A. M.; Bergal-Kuvikas, O.; Shapiro, N.; Taisne, B.; Gordeev, E.; Jaupart, C. P.

2017-12-01

Geochemical data indicate that subduction zone magmas are extracted from the mantle and rises through the crust, with a wide range of volatile contents. The main controls on magma ascent, storage and location of eruptive vents are not well understood. Flow through a volcanic system depends on magma density and viscosity, which depend in turn on chemical composition and volatile content. Thus, one expects that changes of eruption sites in space and time are related to geochemical variations. To test this hypothesis, we have focussed on Klyuchevskoy volcano, Kamchatka, a very active island arc volcano which erupts lavas with a wide range of volatile contents (e.g. 3-7 H20 wt. %). The most primitive high-Mg magmas were able to erupt and build a sizable edifice in an initial phase of activity. As the edifice grew, eruption of these magmas was suppressed in the focal area and occurred in distal parts of the volcano whilst summit eruptions involved differentiated high alumina basalts. Here we propose a new model for the development of the Klyuchevskoy plumbing system which combines edifice load, far field tectonic stress and the presence of volatiles. We calculate dyke trajectories and overpressures by taking into account the exsolution of volatiles in the magma. The most striking result is the progressive deflection of dykes towards the axial area as the edifice size increases. In this model, the critical parameters are the depth of volatile exsolution and the edifice size. Volatile-rich magmas degas at depth and experience a large increase in buoyancy which may overcome edifice-induced stresses at shallow levels. However, as the volcano grows, the stress barrier migrates downwards and may eventually act to stall dykes before gas exsolution takes place. Such conditions are likely to induce the formation of a shallow central reseroir, in which further magma focussing, mixing and contamination may take place. This model accounts for the co-evolution of magma composition and eruptive pattern that is observed at Klychevskoy volcano and should be useful to interpret data from other subduction volcanoes where hydrous magmas play a major role.

Chagas disease vector control and Taylor's law

PubMed Central

Rodríguez-Planes, Lucía I.; Gaspe, María S.; Cecere, María C.; Cardinal, Marta V.

2017-01-01

Background Large spatial and temporal fluctuations in the population density of living organisms have profound consequences for biodiversity conservation, food production, pest control and disease control, especially vector-borne disease control. Chagas disease vector control based on insecticide spraying could benefit from improved concepts and methods to deal with spatial variations in vector population density. Methodology/Principal findings We show that Taylor's law (TL) of fluctuation scaling describes accurately the mean and variance over space of relative abundance, by habitat, of four insect vectors of Chagas disease (Triatoma infestans, Triatoma guasayana, Triatoma garciabesi and Triatoma sordida) in 33,908 searches of people's dwellings and associated habitats in 79 field surveys in four districts in the Argentine Chaco region, before and after insecticide spraying. As TL predicts, the logarithm of the sample variance of bug relative abundance closely approximates a linear function of the logarithm of the sample mean of abundance in different habitats. Slopes of TL indicate spatial aggregation or variation in habitat suitability. Predictions of new mathematical models of the effect of vector control measures on TL agree overall with field data before and after community-wide spraying of insecticide. Conclusions/Significance A spatial Taylor's law identifies key habitats with high average infestation and spatially highly variable infestation, providing a new instrument for the control and elimination of the vectors of a major human disease. PMID:29190728

Improved Critical Eigenfunction Restriction Estimates on Riemannian Surfaces with Nonpositive Curvature

NASA Astrophysics Data System (ADS)

Xi, Yakun; Zhang, Cheng

2017-03-01

We show that one can obtain improved L 4 geodesic restriction estimates for eigenfunctions on compact Riemannian surfaces with nonpositive curvature. We achieve this by adapting Sogge's strategy in (Improved critical eigenfunction estimates on manifolds of nonpositive curvature, Preprint). We first combine the improved L 2 restriction estimate of Blair and Sogge (Concerning Toponogov's Theorem and logarithmic improvement of estimates of eigenfunctions, Preprint) and the classical improved {L^∞} estimate of Bérard to obtain an improved weak-type L 4 restriction estimate. We then upgrade this weak estimate to a strong one by using the improved Lorentz space estimate of Bak and Seeger (Math Res Lett 18(4):767-781, 2011). This estimate improves the L 4 restriction estimate of Burq et al. (Duke Math J 138:445-486, 2007) and Hu (Forum Math 6:1021-1052, 2009) by a power of {(log logλ)^{-1}}. Moreover, in the case of compact hyperbolic surfaces, we obtain further improvements in terms of {(logλ)^{-1}} by applying the ideas from (Chen and Sogge, Commun Math Phys 329(3):435-459, 2014) and (Blair and Sogge, Concerning Toponogov's Theorem and logarithmic improvement of estimates of eigenfunctions, Preprint). We are able to compute various constants that appeared in (Chen and Sogge, Commun Math Phys 329(3):435-459, 2014) explicitly, by proving detailed oscillatory integral estimates and lifting calculations to the universal cover H^2.

Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

PubMed

Cheng, Rui; Xia, Li

2016-11-15

It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

Extraterrestrial resource utilization for economy in space missions

NASA Technical Reports Server (NTRS)

Lewis, J. S.; Ramohalli, K.; Triffet, T.

1990-01-01

The NASA/University of Arizona Space Engineering Research Center is dedicated to research on the discovery, characterization, mapping, beneficiation, extraction, processing, and fabrication of useful products from extraterrestrial material. Schemes for the automated production of low-technology products that are likely to be desired in large quantities in the early stages of any large-scale space activity are identified and developed. This paper summarizes the research program, concentrating upon the production of (1) propellants, both cryogenic and storable, (2) volatiles such as water, nitrogen, and carbon dioxide for use in life-support systems (3) structural metals, and (4) refractories for use in aerobrakes and furnace linings.

Evaluation of Magnetoresistive RAM for Space Applications

NASA Technical Reports Server (NTRS)

Heidecker, Jason

2014-01-01

Magnetoresistive random-access memory (MRAM) is a non-volatile memory that exploits electronic spin, rather than charge, to store data. Instead of moving charge on and off a floating gate to alter the threshold voltage of a CMOS transistor (creating different bit states), MRAM uses magnetic fields to flip the polarization of a ferromagnetic material thus switching its resistance and bit state. These polarized states are immune to radiation-induced upset, thus making MRAM very attractive for space application. These magnetic memory elements also have infinite data retention and erase/program endurance. Presented here are results of reliability testing of two space-qualified MRAM products from Aeroflex and Honeywell.

Logarithmic current measurement circuit with improved accuracy and temperature stability and associated method

DOEpatents

Ericson, M. Nance; Rochelle, James M.

1994-01-01

A logarithmic current measurement circuit for operating upon an input electric signal utilizes a quad, dielectrically isolated, well-matched, monolithic bipolar transistor array. One group of circuit components within the circuit cooperate with two transistors of the array to convert the input signal logarithmically to provide a first output signal which is temperature-dependant, and another group of circuit components cooperate with the other two transistors of the array to provide a second output signal which is temperature-dependant. A divider ratios the first and second output signals to provide a resultant output signal which is independent of temperature. The method of the invention includes the operating steps performed by the measurement circuit.

Children's Early Mental Number Line: Logarithmic or Decomposed Linear?

ERIC Educational Resources Information Center

Moeller, Korbinean; Pixner, Silvia; Kaufmann, Liane; Nuerk, Hans-Christoph

2009-01-01

Recently, the nature of children's mental number line has received much investigation. In the number line task, children are required to mark a presented number on a physical number line with fixed endpoints. Typically, it was observed that the estimations of younger/inexperienced children were accounted for best by a logarithmic function, whereas…

Approximating Exponential and Logarithmic Functions Using Polynomial Interpolation

ERIC Educational Resources Information Center

Gordon, Sheldon P.; Yang, Yajun

2017-01-01

This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is…

How Many Is a Zillion? Sources of Number Distortion

ERIC Educational Resources Information Center

Rips, Lance J.

2013-01-01

When young children attempt to locate the positions of numerals on a number line, the positions are often logarithmically rather than linearly distributed. This finding has been taken as evidence that the children represent numbers on a mental number line that is logarithmically calibrated. This article reports a statistical simulation showing…

Logarithmic Transformations in Regression: Do You Transform Back Correctly?

ERIC Educational Resources Information Center

Dambolena, Ismael G.; Eriksen, Steven E.; Kopcso, David P.

2009-01-01

The logarithmic transformation is often used in regression analysis for a variety of purposes such as the linearization of a nonlinear relationship between two or more variables. We have noticed that when this transformation is applied to the response variable, the computation of the point estimate of the conditional mean of the original response…

Spatially averaged flow over a wavy boundary revisited

USGS Publications Warehouse

McLean, S.R.; Wolfe, S.R.; Nelson, J.M.

1999-01-01

Vertical profiles of streamwise velocity measured over bed forms are commonly used to deduce boundary shear stress for the purpose of estimating sediment transport. These profiles may be derived locally or from some sort of spatial average. Arguments for using the latter procedure are based on the assumption that spatial averaging of the momentum equation effectively removes local accelerations from the problem. Using analogies based on steady, uniform flows, it has been argued that the spatially averaged velocity profiles are approximately logarithmic and can be used to infer values of boundary shear stress. This technique of using logarithmic profiles is investigated using detailed laboratory measurements of flow structure and boundary shear stress over fixed two-dimensional bed forms. Spatial averages over the length of the bed form of mean velocity measurements at constant distances from the mean bed elevation yield vertical profiles that are highly logarithmic even though the effect of the bottom topography is observed throughout the water column. However, logarithmic fits of these averaged profiles do not yield accurate estimates of the measured total boundary shear stress. Copyright 1999 by the American Geophysical Union.

Logarithmic r-θ mapping for hybrid optical neural network filter for multiple objects recognition within cluttered scenes

NASA Astrophysics Data System (ADS)

Kypraios, Ioannis; Young, Rupert C. D.; Chatwin, Chris R.; Birch, Phil M.

2009-04-01

θThe window unit in the design of the complex logarithmic r-θ mapping for hybrid optical neural network filter can allow multiple objects of the same class to be detected within the input image. Additionally, the architecture of the neural network unit of the complex logarithmic r-θ mapping for hybrid optical neural network filter becomes attractive for accommodating the recognition of multiple objects of different classes within the input image by modifying the output layer of the unit. We test the overall filter for multiple objects of the same and of different classes' recognition within cluttered input images and video sequences of cluttered scenes. Logarithmic r-θ mapping for hybrid optical neural network filter is shown to exhibit with a single pass over the input data simultaneously in-plane rotation, out-of-plane rotation, scale, log r-θ map translation and shift invariance, and good clutter tolerance by recognizing correctly the different objects within the cluttered scenes. We record in our results additional extracted information from the cluttered scenes about the objects' relative position, scale and in-plane rotation.

Technology Development for Hydrogen Propellant Storage and Transfer at the Kennedy Space Center (KSC)

NASA Technical Reports Server (NTRS)

Youngquist, Robert; Starr, Stanley; Krenn, Angela; Captain, Janine; Williams, Martha

2016-01-01

The National Aeronautics and Space Administration (NASA) is a major user of liquid hydrogen. In particular, NASA's John F. Kennedy (KSC) Space Center has operated facilities for handling and storing very large quantities of liquid hydrogen (LH2) since the early 1960s. Safe operations pose unique challenges and as a result NASA has invested in technology development to improve operational efficiency and safety. This paper reviews recent innovations including methods of leak and fire detection and aspects of large storage tank health and integrity. We also discuss the use of liquid hydrogen in space and issues we are addressing to ensure safe and efficient operations should hydrogen be used as a propellant derived from in-situ volatiles.

Spatial displacement of release point can enhance activity of an attractant pheromone synergist of a bark beetle.

Treesearch

Brian Sullivan; Kenji Mori

2009-01-01

Flight responses of the southern pine beetle, Dendroctonus frontalis Zimmermann, to widely-spaced (>130 m) traps baited with pine volatiles (in turpentine) and the female-produced pheromone component frontalin were enhanced when a bait containing the male pheromone component (+)-endo-brevicomin was attached...

In-Situ Chemical Reduction and Oxidation of VOCs in Groundwater: Groundwater Treatability Studies

NASA Technical Reports Server (NTRS)

Keith, Amy; Glasgow, Jason; McCaleh, Rececca C. (Technical Monitor)

2001-01-01

This paper presents NASA Marshall Space Flight Center's treatability studies for volatile organic compounds in groundwater. In-Situ groundwater treatment technologies include: 1) Chemical Reduction(Ferox); 2) Chemical Oxidation (Fenton Reagents, Permanganate, and Persulfate); and 3) Thermal (Dynamic Underground Stripping, Six-Phase Heating). This paper is presented in viewgraph form.

Tests Of Protective Coats For Carbon Steel

NASA Technical Reports Server (NTRS)

Macdowell, Louis G., III

1995-01-01

Report describes laboratory and field tests of candidate paints (primers, tie coats, and topcoats) for use in protecting carbon-steel structures against corrosion in seaside environment at Kennedy Space Center. Coating materials selected because of utility in preventing corrosion, also on basis of legal requirements, imposed in several urban areas, for reduction of volatile organic contents.

Mars atmospheric D/H - Consistent with polar volatile theory?

NASA Technical Reports Server (NTRS)

Jakosky, Bruce M.

1990-01-01

Current theories on the Martian water history are discussed on the basis of data for the D/H ratio in the Martian atmosphere (which was found to be enhanced by a factor of 6 + or - relative to the value on earth). In particular, the calculations of Yung et al. (1988), on the basis of their photochemical model, are found to be inconsistent with current theories for the evolution of the polar deposits on Mars. While the photochemical model predicts that about 95 percent of the Martian water has escaped over geologic time and the nonatmospheric reservoir is now only 02 m thick, the polar volatile theory suggest that polar deposits contain the equivalent of tens of meters of water, requiring a more rapid escape of H and D to space than predicted by the photochemical model to match the observed D/H ratio. The paper examines the behavior of the polar caps and the atmospheric water vapor over geologic time and the loss of H and D to space. It is concluded that, at present, it is premature to accept a specific history for water on Mars.

Detrending the realized volatility in the global FX market

NASA Astrophysics Data System (ADS)

Schmidt, Anatoly B.

2009-05-01

There has been growing interest in realized volatility (RV) of financial assets that is calculated using intra-day returns. The choice of optimal time grid for these calculations is not trivial and generally requires analysis of RV dependence on the grid spacing (so-called RV signature). Typical RV signatures have a maximum at the finest time grid spacing available, which is attributed to the microstructure effects. This maximum decays into a plateau at lower frequencies, which implies (almost) stationary return variance. We found that the RV signatures in the modern global FX market may have no plateau or even have a maximum at lower frequencies. Simple averaging methods used to address the microstructure effects in equities have no practical effect on the FX RV signatures. We show that local detrending of the high-frequency FX rate samples yields RV signatures with a pronounced plateau. This implies that FX rates can be described with a Brownian motion having non-stationary trend and stationary variance. We point at a role of algorithmic trading as a possible cause of micro-trends in FX rates.

Volatile Removal Assembly Flight Experiment and KC-135 Packed Bed Experiment: Results and Lessons Learned

NASA Technical Reports Server (NTRS)

Holder, Donald W.; Parker, David

2000-01-01

The Volatile Removal Assembly (VRA) is a high temperature catalytic oxidation process that will be used as the final treatment for recycled water aboard the International Space Station (ISS). The multiphase nature of the process had raised concerns as to the performance of the VRA in a microgravity environment. To address these concerns, two experiments were designed. The VRA Flight Experiment (VRAFE) was designed to test a full size VRA under controlled conditions in microgravity aboard the SPACEHAB module and in a 1 -g environment and compare the performance results. The second experiment relied on visualization of two-phase flow through small column packed beds and was designed to fly aboard NASA's microgravity test bed plane (KC-135). The objective of the KC-135 experiment was to understand the two-phase fluid flow distribution in a packed bed in microgravity. On Space Transportation System (STS) flight 96 (May 1999), the VRA FE was successfully operated and in June 1999 the KC-135 packed bed testing was completed. This paper provides an overview of the experiments and a summary of the results and findings.

Asteroid resources

NASA Technical Reports Server (NTRS)

Lewis, John S.

1992-01-01

There are three types of possible asteroidal materials that appear to be attractive for exploitation: (1) volatiles, (2) free metals, and (3) bulk dirt. Because some of the near-Earth asteroids are energetically more accessible than the Moon (require a round-trip total change in velocity less than 9 km/sec, though the trip time would be measured in years not days), such an asteroid might be chosen as the source of any useful material, even if that material was also available on the Moon. Provided that the asteroid was minable, it might therefore be chosen as the source of bulk dirt needed for shielding in low Earth orbit (LEO) or elsewhere in near-Earth space. And the near-Earth asteroids may offer materials that are rare or absent on the surface of the Moon. The relationship between asteroids and meteorites is discussed. A brief overview of the entire range of meteorite compositions, with emphasis on the occurrence of interesting resources is presented. Focus is on materials useful in space, especially volatiles, metals, and raw dirt. Those few materials that may have sufficiently high market value to be worth returning to Earth will be mentioned.

Logarithmic spiral flap for circular or oval defects on the lateral surface of the nose and nasal ala: a series of 15 cases.

PubMed

Moreno-Artero, E; Redondo, P

2015-10-01

A large number of flaps, particularly rotation and transposition flaps, have been described for the closure of skin defects left by oncologic surgery of the nose. The logarithmic spiral flap is a variant of the rotation flap. We present a series of 15 patients with different types of skin tumor on the nose. The skin defect resulting from excision of the tumor by micrographic surgery was reconstructed using various forms of the logarithmic spiral flap. There are 3 essential aspects to flap design: commencement of the pedicle at the upper or lower border of the wound, a width of the distal end of the flap equal to the vertical diameter of the defect, and a progressive increase in the radius of the spiral from the distal end of the flap to its base. The cosmetic and functional results of surgical reconstruction were satisfactory, and no patient required additional treatment to improve scar appearance. The logarithmic spiral flap is useful for the closure of circular or oval defects situated on the lateral surface of the nose and nasal ala. The flap initiates at one of the borders of the wound as a pedicle with a radius that increases progressively to create a spiral. We propose the logarithmic spiral flap as an excellent option for the closure of circular or oval defects of the nose. Copyright © 2015 Elsevier España, S.L.U. and AEDV. All rights reserved.

The complete two-loop integrated jet thrust distribution in soft-collinear effective theory

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

von Manteuffel, Andreas; Schabinger, Robert M.; Zhu, Hua Xing

2014-03-01

In this work, we complete the calculation of the soft part of the two-loop integrated jet thrust distribution in e+e- annihilation. This jet mass observable is based on the thrust cone jet algorithm, which involves a veto scale for out-of-jet radiation. The previously uncomputed part of our result depends in a complicated way on the jet cone size, r, and at intermediate stages of the calculation we actually encounter a new class of multiple polylogarithms. We employ an extension of the coproduct calculus to systematically exploit functional relations and represent our results concisely. In contrast to the individual contributions, themore » sum of all global terms can be expressed in terms of classical polylogarithms. Our explicit two-loop calculation enables us to clarify the small r picture discussed in earlier work. In particular, we show that the resummation of the logarithms of r that appear in the previously uncomputed part of the two-loop integrated jet thrust distribution is inextricably linked to the resummation of the non-global logarithms. Furthermore, we find that the logarithms of r which cannot be absorbed into the non-global logarithms in the way advocated in earlier work have coefficients fixed by the two-loop cusp anomalous dimension. We also show that in many cases one can straightforwardly predict potentially large logarithmic contributions to the integrated jet thrust distribution at L loops by making use of analogous contributions to the simpler integrated hemisphere soft function.« less

Tomographic location of potential melt-bearing phenocrysts in lunar glass spherules

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

Ebel, D.S.; Fogel, R.A.; Rivers, M.L.

2005-02-04

Apollo 17 orange glass spherules contain olivine phenocrysts with melt inclusions from depth. Tomography (<2micron/pxl) of >200 spherules located 1 phenocryst. We will try to find melt inclusions and obtain original magma volatiles and compositions. In 1971, Apollo 17 astronauts collected a 10 cm soil sample (74220) comprised almost entirely of orange glass spherules. Below this, a double drive-tube core sampled a 68 cm thick horizon comprised of orange glass and black beads (crystallized equivalents of orange glass). Primitive lunar glass spherules (e.g.-A17 orange glasses) are thought to represent ejecta from lunar mare fire fountains. The fire-fountains were apparently drivenmore » by a combination of C-O gas exsolution from orange glass melt and the oxidation of graphite. Upon eruption, magmas lost their volatiles (e.g., S, CO, CO{sub 2}) to space. Evidence for volatile escape remains as volatile-rich coatings on the exteriors of many spherules. Moreover, it showed that Type I and II Fe-Ni-rich metal particles found within orange glass olivine phenocrysts, or free-floating in the glass itself, are powerful evidence for the volatile driving force for lunar fire fountains. More direct evidence for the volatile mechanism has yet to be uncovered. Issues remaining include: the exact composition of magmatic volatiles; the hypothesized existence of graphite in the magma; the oxygen fugacity of the magma and of the lunar interior. In 1996 reported a single {approx}450 micron, equant olivine phenocryst, containing four glassy melt inclusions (or inclusion cores), the largest {approx}30micron in size, in a thin section of the 74001/2 drill core. The melt is assumed to sample the parent magma of the lunar basalts at depth, evidenced by the S content of the inclusion (600 ppm) which is 400 ppm greater than that of the orange glass host. Such melts potentially contain a full complement of the volatile components of the parent magma, which can be analyzed by infrared spectroscopy. Although the A17 orange glass magma is thought to derive from {approx} 400 km depth, the calculations imply a 4 km depth of graphite oxidation (and melt saturation in C-O volatiles) during ascent. We have imaged several hundred similar orange glass spherules, from sample 74220,764, using synchrotron x-ray computer-aided microtomography (XRCMT). Our goals: (1) locate similar phenocrysts containing melt inclusions; (2) analyze phenocrysts to understand the evolution of the magma; (3) analyze melt and fluid inclusions using EPMA and FTIR to obtain direct evidence of magmatic volatiles and pristine bulk compositions.« less

Freezing transition of the directed polymer in a 1+d random medium: Location of the critical temperature and unusual critical properties

NASA Astrophysics Data System (ADS)

Monthus, Cécile; Garel, Thomas

2006-07-01

In dimension d⩾3 , the directed polymer in a random medium undergoes a phase transition between a free phase at high temperature and a low-temperature disorder-dominated phase. For the latter phase, Fisher and Huse have proposed a droplet theory based on the scaling of the free-energy fluctuations ΔF(l)˜lθ at scale l . On the other hand, in related growth models belonging to the Kardar-Parisi-Zhang universality class, Forrest and Tang have found that the height-height correlation function is logarithmic at the transition. For the directed polymer model at criticality, this translates into logarithmic free-energy fluctuations ΔFTc(l)˜(lnl)σ with σ=1/2 . In this paper, we propose a droplet scaling analysis exactly at criticality based on this logarithmic scaling. Our main conclusion is that the typical correlation length ξ(T) of the low-temperature phase diverges as lnξ(T)˜[-ln(Tc-T)]1/σ˜[-ln(Tc-T)]2 , instead of the usual power law ξ(T)˜(Tc-T)-ν . Furthermore, the logarithmic dependence of ΔFTc(l) leads to the conclusion that the critical temperature Tc actually coincides with the explicit upper bound T2 derived by Derrida and co-workers, where T2 corresponds to the temperature below which the ratio ZL2¯/(ZL¯)2 diverges exponentially in L . Finally, since the Fisher-Huse droplet theory was initially introduced for the spin-glass phase, we briefly mention the similarities with and differences from the directed polymer model. If one speculates that the free energy of droplet excitations for spin glasses is also logarithmic at Tc , one obtains a logarithmic decay for the mean square correlation function at criticality, C2(r)¯˜1/(lnr)σ , instead of the usual power law 1/rd-2+η .

Association between characteristics of foveal cystoid spaces and short-term responsiveness to ranibizumab for diabetic macular edema.

PubMed

Murakami, Tomoaki; Suzuma, Kiyoshi; Uji, Akihito; Yoshitake, Shin; Dodo, Yoko; Fujimoto, Masahiro; Yoshitake, Tatsuya; Miwa, Yuko; Yoshimura, Nagahisa

2018-05-01

To investigate the association between the characteristics of foveal cystoid spaces and short-term responsiveness to ranibizumab treatment for diabetic macular edema (DME) at 3 months from the initial injection. We retrospectively reviewed 66 eyes of 61 patients with center-involved DME who received three consecutive ranibizumab injections and following as-needed administrations. We evaluated the relationship between visual improvement at 3 months and the preoperative optical coherence tomography (OCT) parameters including hyperreflective foci, heterogeneous OCT reflectivity, mean levels of OCT reflectivity and height of foveal cystoid spaces. Twenty-three eyes without preoperative hyperreflective foci in the foveal cystoid spaces had significantly greater improvement in the logarithm of the minimum angle of resolution visual acuity (logMAR VA) at 3 months than 43 eyes with foci (P = 0.006). That was similar to the greater reduction in CSF thickness in eyes without lesions after treatment at the same time point (P < 0.001). VA improvement at 3 months was not associated with the height (R = 0.215, P = 0.083) or the reflectivity levels (R = -0.079, P = 0.538) of foveal cystoid spaces. There were no differences in VA changes between eyes with and without heterogeneous reflectivity in foveal cystoid spaces (P = 0.297). Multivariate analyses showed that logMAR VA and the absence of hyperreflective foci in foveal cystoid spaces were associated with VA improvement at 3 months. Hyperreflective foci in foveal cystoid spaces at baseline predict poorer short-term responsiveness to ranibizumab injections for DME.

A Second-Generation Volatile Organic Analyzer for the International Space Station

NASA Technical Reports Server (NTRS)

Limero, Thomas; Reese, Eric; Peters, Randy; James, John T.

1999-01-01

Early in the development of the Crew Health Care System (CHECS) for the International Space Station (ISS), it was recognized that detection of target volatile organic compounds would be a key component of the air monitoring strategy. Experiences during the NASA/Mir program supported the decision to include a real-time volatile organic analyzer (VOA) aboard ISS to help assess the impact of air quality events on crew health and determine the effectiveness of decontamination efforts. Toward this end, a joint development by the Toxicology Laboratory at Johnson Space Center and Graseby Dynamics produced a VOA that has been delivered and is ready for the first 5 years of ISS operation. The first-generation VOA selection criteria included minimizing size, weight, and power consumption while maintaining analytical performance. Measuring available technologies against these criteria, a VOA system based upon gas chromatography/ion mobility spectrometry (GC/IMS) was selected in the mid-90's. However, as NASA looks forward to later-stage ISS operations and to new frontiers such as human exploration of Mars, the ISS VOA (weighing 43 kg and consuming 160 watts) must be replaced by a smaller, less resource-intensive device. This paper will present a possible second-gene ration VOA based upon the same technology as the first-generation unit. Utilizing GC/IMS technology again will permit the instrumental data and experience gained during the initial phase of ISS to be applied to later ISS phases and advanced spacecraft missions. During the past 3 years, efforts to reduce the size of ion mobility spectrometers have been pursued by Graseby Dynamics, the manufacturer of the first-generation VOA. The concept of operation, expected analytical performance, and estimated size of a fully functional second-generation VOA based upon GC/mini-IMS technology will be presented. Furthermore, results of initial laboratory evaluations will be shown.

Volatile Organic Analyzer (VOA) in 2006: Repair, Revalidation, and Restart of Elektron Even

NASA Technical Reports Server (NTRS)

Limero, Thomas

2007-01-01

The Volatile Organic Analyzer (VOA) had been providing valuable data on trace contaminants in the atmosphere of the International Space Station (ISS) from January 2002 through May 2003. Component temperature errors, detected by the VOA s software, shut down the unit in May 2003, but in early 2005 on orbit diagnostics verified fuse failures had disabled both VOA channels. An in-flight maintenance (IFM) session in December 2005 returned the VOA to an operational mode by January 2006. This paper will present the on-orbit data from 2006 that were used to revalidate the VOA, and provide an overview of the VOA s contributions during the Elecktron contingency event that occurred on ISS in September 2006.

Partially confined configuration for the growth of semiconductor crystals from the melt in zero-gravity environment

NASA Technical Reports Server (NTRS)

Lagowski, J.; Gatos, H. C.; Dabkowski, F. P.

1985-01-01

A novel partially confined configuration is proposed for the crystal growth of semiconductors from the melt, including those with volatile constituents. A triangular prism is employed to contain the growth melt. Due to surface tension, the melt will acquire a cylindrical-like shape and thus contact the prism along three parallel lines. The three empty spaces between the cylindrical melt and the edges of the prism will accommodate the expansion of the solidifying semiconductor, and in the case of semiconductor compounds with a volatile constituent, will permit the presence of the desired vapor phase in contact with the melt for controlling the melt stoichiometry. Theoretical and experimental evidence in support of this new type of confinement is presented.

The Origins of Order: Self-Organization and Selection in Evolution

NASA Astrophysics Data System (ADS)

Kauffman, Stuart A.

The following sections are included: * Introduction * Fitness Landscapes in Sequence Space * The NK Model of Rugged Fitness Landscapes * The NK Model of Random Epistatic Interactions * The Rank Order Statistics on K = N - 1 Random Landscapes * The number of local optima is very large * The expected fraction of fitter 1-mutant neighbors dwindles by 1/2 on each improvement step * Walks to local optima are short and vary as a logarithmic function of N * The expected time to reach an optimum is proportional to the dimensionality of the space * The ratio of accepted to tried mutations scales as lnN/N * Any genotype can only climb to a small fraction of the local optima * A small fraction of the genotypes can climb to any one optimum * Conflicting constraints cause a "complexity catastrophe": as complexity increase accessible adaptive peaks fall toward the mean fitness * The "Tunable" NK Family of Correlated Landscapes * Other Combinatorial Optimization Problems and Their Landscapes * Summary * References

Efficient Transition Probability Computation for Continuous-Time Branching Processes via Compressed Sensing.

PubMed

Xu, Jason; Minin, Vladimir N

2015-07-01

Branching processes are a class of continuous-time Markov chains (CTMCs) with ubiquitous applications. A general difficulty in statistical inference under partially observed CTMC models arises in computing transition probabilities when the discrete state space is large or uncountable. Classical methods such as matrix exponentiation are infeasible for large or countably infinite state spaces, and sampling-based alternatives are computationally intensive, requiring integration over all possible hidden events. Recent work has successfully applied generating function techniques to computing transition probabilities for linear multi-type branching processes. While these techniques often require significantly fewer computations than matrix exponentiation, they also become prohibitive in applications with large populations. We propose a compressed sensing framework that significantly accelerates the generating function method, decreasing computational cost up to a logarithmic factor by only assuming the probability mass of transitions is sparse. We demonstrate accurate and efficient transition probability computations in branching process models for blood cell formation and evolution of self-replicating transposable elements in bacterial genomes.

Election Turnout Statistics in Many Countries: Similarities, Differences, and a Diffusive Field Model for Decision-Making

PubMed Central

Borghesi, Christian; Raynal, Jean-Claude; Bouchaud, Jean-Philippe

2012-01-01

We study in details the turnout rate statistics for 77 elections in 11 different countries. We show that the empirical results established in a previous paper for French elections appear to hold much more generally. We find in particular that the spatial correlation of turnout rates decay logarithmically with distance in all cases. This result is quantitatively reproduced by a decision model that assumes that each voter makes his mind as a result of three influence terms: one totally idiosyncratic component, one city-specific term with short-ranged fluctuations in space, and one long-ranged correlated field which propagates diffusively in space. A detailed analysis reveals several interesting features: for example, different countries have different degrees of local heterogeneities and seem to be characterized by a different propensity for individuals to conform to the cultural norm. We furthermore find clear signs of herding (i.e., strongly correlated decisions at the individual level) in some countries, but not in others. PMID:22615762

Nexus of the Cosmic Web

NASA Astrophysics Data System (ADS)

Cautun, Marius; van de Weygaert, Rien; Jones, Bernard J. T.; Frenk, Carlos S.; Hellwing, Wojciech A.

2015-01-01

One of the important unknowns of current cosmology concerns the effects of the large scale distribution of matter on the formation and evolution of dark matter haloes and galaxies. One main difficulty in answering this question lies in the absence of a robust and natural way of identifying the large scale environments and their characteristics. This work summarizes the NEXUS+ formalism which extends and improves our multiscale scale-space MMF method. The new algorithm is very successful in tracing the Cosmic Web components, mainly due to its novel filtering of the density in logarithmic space. The method, due to its multiscale and hierarchical character, has the advantage of detecting all the cosmic structures, either prominent or tenuous, without preference for a certain size or shape. The resulting filamentary and wall networks can easily be characterized by their direction, thickness, mass density and density profile. These additional environmental properties allows to us to investigate not only the effect of environment on haloes, but also how it correlates with the environment characteristics.

Characterization of DBD Plasma Actuators Performance without External Flow . Part I; Thrust-Voltage Quadratic Relationship in Logarithmic Space for Sinusoidal Excitation

NASA Technical Reports Server (NTRS)

Ashpis, David E.; Laun, Matthew C.

2016-01-01

We present results of thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators. We have used a test setup, measurement, and data processing methodology that we developed in prior work. The tests were conducted with High Density Polyethylene (HDPE) actuators of three thicknesses. The applied voltage driving the actuators was a pure sinusoidal waveform. The test setup was suspended actuators with a partial liquid interface. The tests were conducted at low ambient humidity. The thrust was measured with an analytical balance and the results were corrected for anti-thrust to isolate the plasma generated thrust. Applying this approach resulted in smooth and repeatable data. It also enabled curve fitting that yielded quadratic relations between the plasma thrust and voltage in log-log space at constant frequencies. The results contrast power law relationships developed in literature that appear to be a rough approximation over a limited voltage range.

Efficient Transition Probability Computation for Continuous-Time Branching Processes via Compressed Sensing

PubMed Central

Xu, Jason; Minin, Vladimir N.

2016-01-01

Branching processes are a class of continuous-time Markov chains (CTMCs) with ubiquitous applications. A general difficulty in statistical inference under partially observed CTMC models arises in computing transition probabilities when the discrete state space is large or uncountable. Classical methods such as matrix exponentiation are infeasible for large or countably infinite state spaces, and sampling-based alternatives are computationally intensive, requiring integration over all possible hidden events. Recent work has successfully applied generating function techniques to computing transition probabilities for linear multi-type branching processes. While these techniques often require significantly fewer computations than matrix exponentiation, they also become prohibitive in applications with large populations. We propose a compressed sensing framework that significantly accelerates the generating function method, decreasing computational cost up to a logarithmic factor by only assuming the probability mass of transitions is sparse. We demonstrate accurate and efficient transition probability computations in branching process models for blood cell formation and evolution of self-replicating transposable elements in bacterial genomes. PMID:26949377

Modification of the large-scale features of high Reynolds number wall turbulence by passive surface obtrusions

NASA Astrophysics Data System (ADS)

Monty, J. P.; Allen, J. J.; Lien, K.; Chong, M. S.

2011-12-01

A high Reynolds number boundary-layer wind-tunnel facility at New Mexico State University was fitted with a regularly distributed braille surface. The surface was such that braille dots were closely packed in the streamwise direction and sparsely spaced in the spanwise direction. This novel surface had an unexpected influence on the flow: the energy of the very large-scale features of wall turbulence (approximately six-times the boundary-layer thickness in length) became significantly attenuated, even into the logarithmic region. To the author's knowledge, this is the first experimental study to report a modification of `superstructures' in a rough-wall turbulent boundary layer. The result gives rise to the possibility that flow control through very small, passive surface roughness may be possible at high Reynolds numbers, without the prohibitive drag penalty anticipated heretofore. Evidence was also found for the uninhibited existence of the near-wall cycle, well known to smooth-wall-turbulence researchers, in the spanwise space between roughness elements.

Static versus Dynamic Disposition: The Role of GeoGebra in Representing Polynomial-Rational Inequalities and Exponential-Logarithmic Functions

ERIC Educational Resources Information Center

Caglayan, Günhan

2014-01-01

This study investigates prospective secondary mathematics teachers' visual representations of polynomial and rational inequalities, and graphs of exponential and logarithmic functions with GeoGebra Dynamic Software. Five prospective teachers in a university in the United States participated in this research study, which was situated within a…

An Investigation of Students' Errors in Logarithms

ERIC Educational Resources Information Center

Ganesan, Raman; Dindyal, Jaguthsing

2014-01-01

In this study we set out to investigate the errors made by students in logarithms. A test with 16 items was administered to 89 Secondary three students (Year 9). The errors made by the students were categorized using four categories from a framework by Movshovitz-Hadar, Zaslavsky, and Inbar (1987). It was found that students in the top third were…

Can One Take the Logarithm or the Sine of a Dimensioned Quantity or a Unit? Dimensional Analysis Involving Transcendental Functions

ERIC Educational Resources Information Center

Matta, Cherif F.; Massa, Lou; Gubskaya, Anna V.; Knoll, Eva

2011-01-01

The fate of dimensions of dimensioned quantities that are inserted into the argument of transcendental functions such as logarithms, exponentiation, trigonometric, and hyperbolic functions is discussed. Emphasis is placed on common misconceptions that are not often systematically examined in undergraduate courses of physical sciences. The argument…

Decay of Correlations, Quantitative Recurrence and Logarithm Law for Contracting Lorenz Attractors

NASA Astrophysics Data System (ADS)

Galatolo, Stefano; Nisoli, Isaia; Pacifico, Maria Jose

2018-03-01

In this paper we prove that a class of skew products maps with non uniformly hyperbolic base has exponential decay of correlations. We apply this to obtain a logarithm law for the hitting time associated to a contracting Lorenz attractor at all the points having a well defined local dimension, and a quantitative recurrence estimation.

Dead-time compensation for a logarithmic display rate meter

DOEpatents

Larson, John A.; Krueger, Frederick P.

1988-09-20

An improved circuit is provided for application to a radiation survey meter that uses a detector that is subject to dead time. The circuit compensates for dead time over a wide range of count rates by producing a dead-time pulse for each detected event, a live-time pulse that spans the interval between dead-time pulses, and circuits that average the value of these pulses over time. The logarithm of each of these values is obtained and the logarithms are subtracted to provide a signal that is proportional to a count rate that is corrected for the effects of dead time. The circuit produces a meter indication and is also capable of producing an audible indication of detected events.

Dead-time compensation for a logarithmic display rate meter

DOEpatents

Larson, J.A.; Krueger, F.P.

1987-10-05

An improved circuit is provided for application to a radiation survey meter that uses a detector that is subject to dead time. The circuit compensates for dead time over a wide range of count rates by producing a dead-time pulse for each detected event, a live-time pulse that spans the interval between dead-time pulses, and circuits that average the value of these pulses over time. The logarithm of each of these values is obtained and the logarithms are subtracted to provide a signal that is proportional to a count rate that is corrected for the effects of dead time. The circuit produces a meter indication and is also capable of producing an audible indication of detected events. 5 figs.

Nonvolatile Memory Technology for Space Applications

NASA Technical Reports Server (NTRS)

Oldham, Timothy R.; Irom, Farokh; Friendlich, Mark; Nguyen, Duc; Kim, Hak; Berg, Melanie; LaBel, Kenneth A.

2010-01-01

This slide presentation reviews several forms of nonvolatile memory for use in space applications. The intent is to: (1) Determine inherent radiation tolerance and sensitivities, (2) Identify challenges for future radiation hardening efforts, (3) Investigate new failure modes and effects, and technology modeling programs. Testing includes total dose, single event (proton, laser, heavy ion), and proton damage (where appropriate). Test vehicles are expected to be a variety of non-volatile memory devices as available including Flash (NAND and NOR), Charge Trap, Nanocrystal Flash, Magnetic Memory (MRAM), Phase Change--Chalcogenide, (CRAM), Ferroelectric (FRAM), CNT, and Resistive RAM.

Fundamental Study on the Ozone Posttreatment of Reverse Osmosis Permeates from Army Wastewaters.

DTIC Science & Technology

1981-03-01

organics in RC per- meates as well as for the intermediates formed during ozonation of RO permeate. / This involved the use of distillation, head space...This involved the use of distillation, head - space, and purge and trap methods for the concentration of volatile organic constituents and of the...Grams Group 1 Soap 6.26 INaC 1 7 *C Urea 0.0917 Kaolin 1.725 Talc 1 .7i3 Sho%er Clearer 9.0( Group 2 Hail Oil 14.18 Hai I Gel 3.36 Shampoo 0.456

Volatiles Delivery to the Terrestrial Planets

NASA Astrophysics Data System (ADS)

Marov, M. Ya.; Ipatov, S. I.

2006-08-01

Migration of small bodies and dust particles from the outer regions of the solar system is an important mechanism of the formation and evolution of atmospheres and hydrospheres of the terrestrial planets [1]. It is assumed that these bodies and particles could be responsible for the delivery of the original matter (mainly volatiles) and thus could give rise to the life origin. A fraction of dust particles migrated inward solar system is believed to be of interstellar origin embedded in presolar nebula and preserved for a long time at the fringe of the solar system. Our studies of volatiles delivery were based on results of numerical integration of the migration of small bodies and dust particles in the Solar System [2]. It was shown that the exogenous mechanism of heterogeneous accretion and the endogenous mechanism of the interior degassing may contribute to the formation of planetary atmospheres and hydrospheres at least comparably. If the total mass of planetesimals beyond Jupiter's orbit exceeded a hundred of Earth masses, then of the total mass of volatiles delivered to the Earth exceeded the amount of water in the Earth's oceans. The results of our studies of the migration of dust particles of various genesis lead to the conclusion that a portion of cometary and trans-Neptunian dust particles highly enriched by volatiles can be considerable among particles of other origin. Although it is difficult to obtain exact estimates of the dust influx to the Earth and neighboring planets, it was shown that, in comparison with small bodies, the dust contribution is 3-4 orders of magnitude smaller. However, dust particles could have been most efficient in the delivery of organic prebiogenic and, most likely, biogenic matter, because they are subjected to substantially weaker heating at the altitudes at which they enter the atmosphere and decelerate in it. This conclusion is confirmed by laboratory investigations into the probability of survival of bacteria and phages heated up to 200^o C and allows one to consider dust as a potential carrier of biogenic material from outer space. [1] Marov M. Ya. and Ipatov S.I., Solar System Research, 2005, 39, 374-380. [2] Ipatov S.I. and Mather J.C., Advances in Space Research, 2006, 37, 126-137.

Volatile Analysis by Pyrolysis of Regolith (Vapor) on the Moon using Mass Spectrometry

NASA Technical Reports Server (NTRS)

Glavin, D. P.; Kate, I. L. ten; Brinckerhoff, W.; Cardiff, E.; Dworkin, J. P.; Feng, S.; Getty, S.; Gorevan, S.; Harpold, D.; Jones, A. L.;

Isolation and characterization of microorganisms and volatiles associated with Moroccan saffron during different processing treatments.

PubMed

Fancello, Francesco; Petretto, Giacomo; Sanna, Maria Lina; Pintore, Giorgio; Lage, Mounira; Zara, Severino

2018-05-20

Saffron may be spoiled by a variety of microorganisms during cultivation, harvesting, and post harvesting. As saffron can be dried and stored in different ways, this preliminary study explored the natural microbiota present in Moroccan saffron when subjected to different drying techniques. An analysis of the carotenoid-derived volatiles present in the saffron was also carried out. The culturable microbiota of the saffron samples dried using different methods, namely in the shade (also called natural), in the sun, or in the oven, were studied using classical and molecular approaches. The effect of the drying methods on head-space chemical volatiles was also determined. Eighty-two isolates grown in the different culture media were chosen from the colonies, and genotype analysis grouped the microorganisms into 58 clusters, revealing a wide diversity. Out of the 82 isolates, 75 belonged to the Bacillaceae family. The other isolates were distributed within the Dietziaceae, Paenibacillaceae and Carnobacteriaceae families. The dominant species was Bacillus simplex, which was detected in all samples, regardless of the drying method used. Lysinibacillus macroides was dominant in the sun-dried saffron. No pathogens were isolated, but an isolate belonging to Dietzia maris, a potential human pathogenic species, was detected. The biodiversity indexes were linked to the drying method and generally decreased as the intensity of the treatment increased. The results of this preliminary work show that the different drying methods strongly influenced the microbiota and affect the saffron volatile profile. Further analysis will be needed to determine possible effects of selected microbiota on saffron volatiles. Copyright © 2018 Elsevier B.V. All rights reserved.

Martian Surface and Atmosphere Workshop

NASA Astrophysics Data System (ADS)

Schuraytz, Benjamin C.

The NASA-sponsored Martian Surface and Atmosphere Through Time Study Project convened its first major meeting at the University of Colorado in Boulder, September 23-25, 1991. The workshop, co-sponsored by the Lunar and Planetary Institute (LPI) and the Laboratory for Atmospheric and Space Physics at the University of Colorado, brought together an international group of 125 scientists to discuss a variety of issues relevant to the goals of the MSATT Program. The workshop program committee included co-convenors Robert Haberle, MSATT Steering Committee Chairman NASA Ames Research Center) and Bruce Jakosky (University of Colorado), and committee members Amos Banin (NASA Ames Research Center and Hebrew University), Benjamin Schuraytz (LPI), and Kenneth Tanaka (U.S. Geological Survey, Flagstaff, Ariz.).The purpose of the workshop was to begin exploring and defining the relationships between different aspects of Mars science—the evolution of the surface, the atmosphere, upper atmosphere, volatiles, and climate. Specific topics addressed in the 88 contributed abstracts included the current nature of the surface with respect to physical properties and photometric observations and interpretations; the history of geological processes, comprising water and ice-related geomorphology, impact cratering, and volcanism; and the geochemistry and mineralogy of the surface with emphasis on compositional and spectroscopic studies and weathering processes. Also addressed were the present atmosphere, focusing on structure and dynamics, volatile and dust distribution, and the upper atmosphere; long-term volatile evolution based on volatiles in SNC meteorites (certain meteorites thought to have come from Mars) and atmospheric evolution processes; climate history and volatile cycles in relation to early climate and the polar caps, ground ice, and regolith; and future mission concepts.

A Monte-Carlo Analysis of Organic Aerosol Volatility with Aerosol Microphysics

NASA Astrophysics Data System (ADS)

Gao, C. Y.; Tsigaridis, K.; Bauer, S. E.

2016-12-01

A newly developed box model scheme, MATRIX-VBS, includes the volatility-basis set (VBS) framework in an aerosol microphysical scheme MATRIX (Multiconfiguration Aerosol TRacker of mIXing state), which resolves aerosol mass and number concentrations and aerosol mixing state. The new scheme advanced the representation of organic aerosols in Earth system models by improving the traditional and simplistic treatment of organic aerosols as non-volatile and with a fixed size distribution. Further development includes adding the condensation of organics on coarse mode aerosols - dust and sea salt, thus making all organics in the system semi-volatile. To test and simplify the model, a Monte-Carlo analysis is performed to pin point which processes affect organics the most under which chemical and meteorological conditions. Since the model's parameterizations have the ability to capture a very wide range of conditions, from very clean to very polluted and for a wide range of meteorological conditions, all possible scenarios on Earth across the whole parameter space, including temperature, location, emissions and oxidant levels, are examined. The Monte-Carlo simulations provide quantitative information on the sensitivity of the newly developed model and help us understand how organics are affecting the size distribution, mixing state and volatility distribution at varying levels of meteorological conditions and pollution levels. In addition, these simulations give information on which parameters play a critical role in the aerosol distribution and evolution in the atmosphere and which do not, that will facilitate the simplification of the box model, an important step in its implementation in the global model.

Selection of adsorption traps for in situ gas chromatographic analysis of polar regolith volatiles on board of the Luna-Resource lander

NASA Astrophysics Data System (ADS)

Aseev, Sergey; Gerasimov, Mikhail; Zaitsev, Maxim

Investigation of volatile species in the polar regions of the Moon is an important task for better understanding of its evolution and for further exploration, in particular, to provide resources for future permanent stations. Gas chromatographic complex of Space Research Institute of the Russian Academy of Science is focused on measurements of volatile compounds composition, supposedly existing in the polar regions of the Moon in the area of Luna-Resource probe landing (2017). Also, this devise can be used on the Mars in the area of ExoMars landing mission (2018). One of the features of this gas analytical system is the use of adsorption traps, which can retain volatile compounds continuously coming into the gas chromatograph as a result of pyrolysis of the regolith sample and shortly release them for injection into chromatographic system for analysis. To improve sensitivity and analytical properties of the gas chromatograph, it’s necessary to provide concentrated injection of all the volatile components, which were released during pyrolysis of the regolith sample. It takes ~15 minutes to complete this pyrolysis operation. Such permanent gases as noble gases and N2, Ar, CO on the left hand have low dynamic viscosity, which cause their short retention time in adsorption traps, but on the right hand - these gases are released from the soil sample close to the end of the heating cycle. Summarizing these principles, we can say that 5 minutes of trapping for specified gases is efficient enough for their accumulation with consequent heating of adsorption trap up to 150°C to produce concentrated injection of all these compounds to the analytical columns of gas chromatography system. In the most of space missions (Viking, Phoenix, MSL, Rosetta), which use gas chromatography as the main method for in situ chemical analysis of volatiles, chromatography columns are usually mounted in parallel scheme. It is well known that water has a negative influence on analytical characteristics of several chromatography columns types. This can take place because water can fill absorption pours, and this can result in column’s retention time and capacity variation. The use of adsorption traps can preserve chromatography columns from negative influence of some compounds and improve threshold of detection by several orders of magnitude in the analysis of volatiles composition of planetary soils, as well as in direct atmospheric measurements. The paper is dedicated to the investigation of typical retention time for noble and permanent gases, such as CO2, CO, CH4, N2, Ar on the adsorbents Carbosieve, PoraPak Q and Molsieve 5A , depending on their cooling temperature. Based on results of the measurements we developed and tested new experimental techniques suitable for analysis of different adsorbents types, which can be used as a new basis for future adsorption traps. Acknowledgements: This work was supported in part by P-22 Program of the RAS.

Walkability and walking for transport: characterizing the built environment using space syntax.

PubMed

Koohsari, Mohammad Javad; Owen, Neville; Cerin, Ester; Giles-Corti, Billie; Sugiyama, Takemi

2016-11-24

Neighborhood walkability has been shown to be associated with walking behavior. However, the availability of geographical data necessary to construct it remains a limitation. Building on the concept of space syntax, we propose an alternative walkability index, space syntax walkability (SSW). This study examined associations of the full walkability index and SSW with walking for transport (WT). Data were collected in 2003-2004 from 2544 adults living in 154 Census Collection Districts (CCD) in Adelaide, Australia. Participants reported past week WT frequency. Full walkability (consisting of net residential density, intersection density, land use mix, and net retail area ratio) and SSW (consisting of gross population density and a space syntax measure of street integration) were calculated for each CCD using geographic information systems and space syntax software. Generalized linear models with negative binomial variance and logarithmic link functions were employed to examine the associations of each walkability index with WT frequency, adjusting for socio-demographic variables. Two walkability indices were closely correlated (ρ = 0.76, p < 0.01). The associations of full walkability and SSW with WT frequency were positive, with regression coefficients of 1.12 (95% CI: 1.08, 1.17) and 1.14 (95% CI: 1.10, 1.19), respectively. SSW employs readily-available geographic data, yet is comparable to full walkability in its association with WT. The concept and methods of space syntax provide a novel approach to further understanding how urban design influences walking behaviors.

Effects of ultrasound energy density on the non-thermal pasteurization of chocolate milk beverage.

PubMed

Monteiro, Sara H M C; Silva, Eric Keven; Alvarenga, Verônica O; Moraes, Jeremias; Freitas, Mônica Q; Silva, Márcia C; Raices, Renata S L; Sant'Ana, Anderson S; Meireles, M Angela A; Cruz, Adriano G

2018-04-01

This study presents the emerging high-intensity ultrasound (HIUS) processing as a non-thermal alternative to high-temperature short-time pasteurization (HTST). Chocolate milk beverage (CMB) was subjected to different ultrasound energy densities (0.3-3.0 kJ/cm 3 ), as compared to HTST pasteurization (72 °C/15 s) aimed to verify the effect of the HIUS processing on the microbiological and physicochemical characteristics of the beverage. The application of HIUS at an energy density of 3.0 kJ/cm 3 was able to reduce 3.56 ± 0.02 logarithmic cycles in the total aerobic counts. In addition, the ultrasound energy density affected the physical properties of the beverage as the size distribution of fat globule and rheological behavior, as well as the chemical properties such as antioxidant activity, ACE inhibitory activity, fatty acid profile, and volatile profile. In general, the different energetic densities used as a non-thermal method of pasteurization of CMB were more effective when compared to the conventional pasteurization by HTST, since they improved the microbiological and physicochemical quality, besides preserving the bioactive compounds and the nutritional quality of the product. Copyright © 2017 Elsevier B.V. All rights reserved.

Venting test analysis using Jacob`s approximation

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

Edwards, K.B.

1996-03-01

There are many sites contaminated by volatile organic compounds (VOCs) in the US and worldwide. Several technologies are available for remediation of these sites, including excavation, pump and treat, biological treatment, air sparging, steam injection, bioventing, and soil vapor extraction (SVE). SVE is also known as soil venting or vacuum extraction. Field venting tests were conducted in alluvial sands residing between the water table and a clay layer. Flow rate, barometric pressure, and well-pressure data were recorded using pressure transmitters and a personal computer. Data were logged as frequently as every second during periods of rapid change in pressure. Testsmore » were conducted at various extraction rates. The data from several tests were analyzed concurrently by normalizing the well pressures with respect to extraction rate. The normalized pressures vary logarithmically with time and fall on one line allowing a single match of the Jacob approximation to all tests. Though the Jacob approximation was originally developed for hydraulic pump test analysis, it is now commonly used for venting test analysis. Only recently, however, has it been used to analyze several transient tests simultaneously. For the field venting tests conducted in the alluvial sands, the air permeability and effective porosity determined from the concurrent analysis are 8.2 {times} 10{sup {minus}7} cm{sup 2} and 20%, respectively.« less

Reducing variation in decomposition odour profiling using comprehensive two-dimensional gas chromatography.

PubMed

Perrault, Katelynn A; Stefanuto, Pierre-Hugues; Stuart, Barbara H; Rai, Tapan; Focant, Jean-François; Forbes, Shari L

2015-01-01

Challenges in decomposition odour profiling have led to variation in the documented odour profile by different research groups worldwide. Background subtraction and use of controls are important considerations given the variation introduced by decomposition studies conducted in different geographical environments. The collection of volatile organic compounds (VOCs) from soil beneath decomposing remains is challenging due to the high levels of inherent soil VOCs, further confounded by the use of highly sensitive instrumentation. This study presents a method that provides suitable chromatographic resolution for profiling decomposition odour in soil by comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry using appropriate controls and field blanks. Logarithmic transformation and t-testing of compounds permitted the generation of a compound list of decomposition VOCs in soil. Principal component analysis demonstrated the improved discrimination between experimental and control soil, verifying the value of the data handling method. Data handling procedures have not been well documented in this field and standardisation would thereby reduce misidentification of VOCs present in the surrounding environment as decomposition byproducts. Uniformity of data handling and instrumental procedures will reduce analytical variation, increasing confidence in the future when investigating the effect of taphonomic variables on the decomposition VOC profile. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toward an International Lunar Polar Volatiles Strategy

NASA Technical Reports Server (NTRS)

Gruener, J. E.; Suzuki, N. H.; Carpenter, J. D.

2015-01-01

Fourteen international space agencies are participating in the International Space Exploration Coordination Group (ISECG), working together to advance a long-range human space exploration strategy. The ISECG is a voluntary, non-binding international coordination mechanism through which individual agencies may exchange information regarding interests, objectives, and plans in space exploration with the goal of strengthening both individual exploration programs as well as the collective effort. The ISECG has developed a Global Exploration Roadmap (GER) that reflects the coordinated international dialog and continued preparation for exploration beyond low-Earth orbit - beginning with the Moon and cis-lunar space, and continuing to near-Earth asteroids, and Mars. Space agencies agree that human space exploration will be most successful as an international endeavor, given the challenges of these missions. The roadmap demonstrates how initial capabilities can enable a variety of missions in the lunar vicinity, responding to individual and common goals and objectives, while contributing to building partnerships required for sustainable human space exploration that delivers value to the public.

A Theoretical Investigation of Oxidation Efficiency of a Volatile Removal Assembly Reactor Under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Guo, Boyun

2005-01-01

Volatile Removal Assembly (VRA) is a subsystem of the Closed Environment Life Support System (CELSS) installed in the International Space Station. It is used for removing contaminants (volatile organics) in the wastewater produced by the space station crews. The major contaminants are formic acid, ethanol, and propylene glycol. The VRA contains a slim packbed reactor (3.5 cm diameter and four 28 cm long tubes in series) to perform catalyst oxidation of wastewater at elevated pressure and temperature under microgravity conditions. In the reactor, the contaminants are burned with oxygen gas (O2) to form water and carbon dioxide (CO2) that dissolves in the water stream. Optimal design of the reactor requires a thorough understanding about how the reactor performs under microgravity conditions. The objective of this study was to develop a mathematical model to interpret experimental data obtained from normal and microgravity conditions, and to predict the performance of VRA reactor under microgravity conditions. Catalyst oxidation kinetics and the total oxygen-water contact area control the efficiency of catalyst oxidation for mass transfer, which depends on oxygen gas holdup and distribution in the reactor. The process involves bubbly flow in porous media with chemical reactions in microgravity environment. This presents a unique problem in fluid dynamics that has not been studied. Guo et al. (2004) developed a mathematical model that predicts oxygen holdup in the VRA reactor. No mathematical model has been found in the literature that can be used to predict the efficiency of catalyst oxidation under microgravity conditions.

Sensitivity of Hollow Fiber Spacesuit Water Membrane Evaporator Systems to Potable Water Constituents, Contaminants and Air Bubbles

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Trevino, Luis A.; Fritts, Sharon; Tsioulos, Gus

2008-01-01

The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning and compares the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source. Some of the impurities in potable water are volatile, such as the organics, while others, such as the metals and inorganic ions are nonvolatile. The non-volatile constituents will concentrate in the SWME as evaporated water from the loop is replaced by the feedwater. At some point in the SWME mission lifecycle as the concentrations of the non-volatiles increase, the solubility limits of one or more of the constituents may be reached. The resulting presence of precipitate in the coolant water may begin to plug pores and tube channels and affect the SWME performance. Sensitivity to macroparticles, lunar dust simulant, and air bubbles will also be investigated.

An overview of atmosphere and plasma observations planned for the New Horizons flyby of 2014 MU69

NASA Astrophysics Data System (ADS)

Gladstone, R.; Young, L. A.; Parker, J. W.; Elliott, H. A.; Hill, M. E.; Piquette, M. R.; Stern, A.; Weaver, H. A., Jr.; Olkin, C.; Spencer, J. R.

2017-12-01

Due to its small size, it is highly likely that all volatiles that might have once been present on 2014 MU69 are now gone, having long ago escaped to space. However, it is possible that 2014 MU69 retains some volatiles (e.g., methanol, acetylene, ethane, hydrogen cyanide, ammonia) at the present day. Although these volatiles are likely quite stable on the surface at their current temperature, ongoing radiation processing and occasional impacts provide a possible source for a transient atmosphere. Such a transient atmosphere will be searched for by the Alice ultraviolet spectrograph, e.g., in absorption, using stellar and solar appulses, and in emission, using resonantly scattered solar emissions. Dust associated with 2014 MU69 will be searched for with high phase angle LORRI and MVIC imaging, and with in situ SDC observations. In addition, the particle and plasma environment of KBOs is largely unknown. SWAP and PEPSSI observations will establish the interaction of the interplanetary medium with 2014 MU69, e.g., looking for pickup ions resulting from sputtering of surface materials. Although it is likely that only upper limits will be set on neutrals and ions in the vicinity of 2014 MU69, the New Horizons observations will characterize the fluxes of UV, solar wind, interstellar pickup ions, and energetic particles, i.e., space weathering, that can modify the surface of 2014 MU69 and other KBOs. In this presentation, we will outline the plans for New Horizons plasma and atmospheres observations during the flyby of 2014 MU69.

A review of emerging non-volatile memory (NVM) technologies and applications

NASA Astrophysics Data System (ADS)

Chen, An

2016-11-01

This paper will review emerging non-volatile memory (NVM) technologies, with the focus on phase change memory (PCM), spin-transfer-torque random-access-memory (STTRAM), resistive random-access-memory (RRAM), and ferroelectric field-effect-transistor (FeFET) memory. These promising NVM devices are evaluated in terms of their advantages, challenges, and applications. Their performance is compared based on reported parameters of major industrial test chips. Memory selector devices and cell structures are discussed. Changing market trends toward low power (e.g., mobile, IoT) and data-centric applications create opportunities for emerging NVMs. High-performance and low-cost emerging NVMs may simplify memory hierarchy, introduce non-volatility in logic gates and circuits, reduce system power, and enable novel architectures. Storage-class memory (SCM) based on high-density NVMs could fill the performance and density gap between memory and storage. Some unique characteristics of emerging NVMs can be utilized for novel applications beyond the memory space, e.g., neuromorphic computing, hardware security, etc. In the beyond-CMOS era, emerging NVMs have the potential to fulfill more important functions and enable more efficient, intelligent, and secure computing systems.

Nonglobal correlations in collider physics

DOE PAGES

Moult, Ian; Larkoski, Andrew J.

2016-01-13

Despite their importance for precision QCD calculations, correlations between in- and out-of-jet regions of phase space have never directly been observed. These so-called non-global effects are present generically whenever a collider physics measurement is not explicitly dependent on radiation throughout the entire phase space. In this paper, we introduce a novel procedure based on mutual information, which allows us to isolate these non-global correlations between measurements made in different regions of phase space. We study this procedure both analytically and in Monte Carlo simulations in the context of observables measured on hadronic final states produced in e+e- collisions, though itmore » is more widely applicable.The procedure exploits the sensitivity of soft radiation at large angles to non-global correlations, and we calculate these correlations through next-to-leading logarithmic accuracy. The bulk of these non-global correlations are found to be described in Monte Carlo simulation. They increase by the inclusion of non-perturbative effects, which we show can be incorporated in our calculation through the use of a model shape function. As a result, this procedure illuminates the source of non-global correlations and has connections more broadly to fundamental quantities in quantum field theory.« less

ERS-1 scatterometer calibration and validation activities at ECMWF. B: From radar backscatter characteristics to wind vector solutions

NASA Technical Reports Server (NTRS)

Stoffelen, AD; Anderson, David L. T.; Woiceshyn, Peter M.

1992-01-01

Calibration and validation activities for the ERS-1 scatterometer were carried out at ECMWF (European Center for Medium range Weather Forecast) complementary to the 'Haltenbanken' field campaign off the coast of Norway. At a Numerical Weather Prediction (NWP) center a wealth of verifying data is available both in time and space. This data is used to redefine the wind retrieval procedure given the instrumental characteristics. It was found that a maximum likelihood estimation procedure to obtain the coefficients of a reformulated sigma deg to wind relationship should use radar measurements in logarithmic rather than physical space, and use winds as the wind components rather than wind speed and direction. Doing this, a much more accurate transfer function than the one currently operated by ESA was derived. Sigma deg measurement space shows no signature of a separation in an upwind solution cone and a downwind solution cone. As such signature was anticipated in ESA's wind direction ambiguity removal algorithm, reconsideration of the procedure is necessary. Despite the fact that revisions have to be made in the process of wind retrieval; a grid potential is shown for scatterometry in meteorology and climatology.

Spacewire router IP-core with priority adaptive routing

NASA Astrophysics Data System (ADS)

Shakhmatov, A. V.; Chekmarev, S. A.; Vergasov, M. Y.; Khanov, V. Kh

2015-10-01

Design of modern spacecraft focuses on using network principles of interaction on-board equipment, in particular in network SpaceWire. Routers are an integral part of most SpaceWire networks. The paper presents an adaptive routing algorithm with a prioritization, allowing more flexibility to manage the routing process. This algorithm is designed to transmit SpaceWire packets over a redundant network. Also a method is proposed for rapid restoration of working capacity after power by saving the routing table and the router configuration in an external non-volatile memory. The proposed solutions used to create IP-core router, and then tested in the FPGA device. The results illustrate the realizability and rationality of the proposed solutions.

Exploring Surface Analysis Techniques for the Detection of Molecular Contaminants on Spacecraft

NASA Technical Reports Server (NTRS)

Rutherford, Gugu N.; Seasly, Elaine; Thornblom, Mark; Baughman, James

2016-01-01

Molecular contamination is a known area of concern for spacecraft. To mitigate this risk, projects involving space flight hardware set requirements in a contamination control plan that establishes an allocation budget for the exposure of non-volatile residues (NVR) onto critical surfaces. The purpose of this work will focus on non-contact surface analysis and in situ monitoring to mitigate molecular contamination on space flight hardware. By using Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM-EDS) with Raman Spectroscopy, an unlikely contaminant was identified on space flight hardware. Using traditional and surface analysis methods provided the broader view of the contamination sources allowing for best fit solutions to prevent any future exposure.

Teaching Is ... Opening up Spaces to Explore Academic Work in Fluid and Volatile Times

ERIC Educational Resources Information Center

Sadler, Kirsten; Selkrig, Mark; Manathunga, Catherine

2017-01-01

Universities are built upon the collaborative work of academic staff and students, yet the nature of this work has been undergoing profound and rapid change. Pressures within Australia's higher education sector have led to a fracturing of traditional academic roles and growing feelings of disconnection. While there have been many narrative,…

Radiation in the universe

NASA Technical Reports Server (NTRS)

Stuhlinger, Ernst; Truemper, Joachim; Weisskopf, Martin

1992-01-01

When Wilhelm Conrad Roentgen discovered radiation one hundred years ago, it seemed that what was discovered was one of the rarest and most volatile members of the family of the basic modules of our natural world. Today cosmologists report that a substantial part of the universe's radiation energy consists of X-rays, which travel through cosmic space with the speed of light.

Exobiology and life science

NASA Technical Reports Server (NTRS)

Mckay, C. P.

1987-01-01

The following types of experiments for a proposed Space Station Microgravity Particle Research Facility are described: (1) biogenic elements in the interstellar medium; (2) organic material in the solar nebula; (3) volatiles in comets and icy planetesimals; (4) pre-biotic atmospheric chemistry; (5) analysis of cosmic dust particles; and (6) microbial exposure. The required capabilities and desired hardware for the facility are detailed.

MS Dunbar works onboard Spacehab

NASA Image and Video Library

1998-03-04

S89-E-5285 (25 Jan 1998) --- This Electronic Still Camera (ESC) image shows mission specialist Bonnie J. Dunbar, payload commander, working in the Spacehab Module onboard the Space Shuttle Endeavour. Dunbar is working with RME-1326, a Risk Mitigation Experiment (RME) at the Volatile Removal Assembly (VRA). This ESC view was taken on January 25, 1998 at 13:16:22 GMT.

A Five-year Performance Study of Low VOC Coatings over Zinc Thermal Spray for the Protection of Carbon Steel at the Kennedy Space Center

NASA Technical Reports Server (NTRS)

Kolody, Mark R.; Curran, Jerome P.; Calle, Luz Marina

2014-01-01

The launch facilities at the Kennedy Space Center (KSC) are located approximately 1000 feet from the Atlantic Ocean where they are exposed to salt deposits, high humidity, high UV degradation, and acidic exhaust from solid rocket boosters. These assets are constructed from carbon steel, which requires a suitable coating to provide long-term protection to reduce corrosion and its associated costs. While currently used coating systems provide excellent corrosion control performance, they are subject to occupational, safety, and environmental regulations at the Federal and State levels that limit their use. Many contain high volatile organic compounds (VOCs), hazardous air pollutants, and other hazardous materials. Hazardous waste from coating operations include vacuum filters, zinc dust, hazardous paint related material, and solid paint. There are also worker safety issues such as exposure to solvents and isocyanates. To address these issues, top-coated thermal spray zinc coating systems were investigated as a promising environmentally friendly corrosion protection for carbon steel in an acidic launch environment. Additional benefits of the combined coating system include a long service life, cathodic protection to the substrate, no volatile contaminants, and high service temperatures. This paper reports the results of a performance based study to evaluate low VOC topcoats (for thermal spray zinc coatings) on carbon steel for use in a space launch environment.

A Colorimetric Sensor for Qualitative Discrimination and Quantitative Detection of Volatile Amines

PubMed Central

Tang, Zhonglin; Yang, Jianhua; Yu, Junyun; Cui, Bo

2010-01-01

We have developed a novel colorimetric sensor based on a digital camera and white LED illumination. Colorimetric sensor arrays (CSAs) were made from a set of six chemically responsive dyes impregnated on an inert substrate plate by solution casting. Six common amine aqueous solutions, including dimethylamine, triethylamine, diisopropylamine, aniline, cyclohexylamine, and pyridine vaporized at 25 °C and six health-related trimethylamine (TMA) concentrations including 170 ppm, 51 ppm, 8 ppm, 2 ppm, 125 ppb and 50 ppb were analyzed by the sensor to test its ability for the qualitative discrimination and quantitative detection of volatile amines. We extracted the feature vectors of the CSA's response to the analytes from a fusional color space, which was obtained by conducting a joint search algorithm of sequential forward selection and sequential backward selection (SFS&SBS) based on the linear discriminant criteria (LDC) in a mixed color space composed of six common color spaces. The principle component analysis (PCA) followed by the hierarchical cluser analysis (HCA) were utilized to discriminate 12 analytes. Results showed that the colorimetric sensor grouped the six amine vapors and five TMA concentrations correctly, while TMA concentrations of 125 ppb and 50 ppb were indiscriminable from each other. The limitation of detection (LOD) of the sensor for TMA was found to be lower than 50 ppb. The CSAs were reusable for TMA concentrations below 8 ppm. PMID:22163560

Monotonicity and Logarithmic Concavity of Two Functions Involving Exponential Function

ERIC Educational Resources Information Center

Liu, Ai-Qi; Li, Guo-Fu; Guo, Bai-Ni; Qi, Feng

2008-01-01

The function 1 divided by "x"[superscript 2] minus "e"[superscript"-x"] divided by (1 minus "e"[superscript"-x"])[superscript 2] for "x" greater than 0 is proved to be strictly decreasing. As an application of this monotonicity, the logarithmic concavity of the function "t" divided by "e"[superscript "at"] minus "e"[superscript"(a-1)""t"] for "a"…

Portable geiger counter with logarithmic scale (in Portuguese)

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

Oliveira, L.A.C.; de Andrade Chagas, E.; de Bittencourt, F.A.

1971-06-01

From 23rd annual meeting of the Brazilian Society for the Advancement of Science; Curitiba, Brazil (4 Jul 1971). A portable scaler with logarithmic scale covering 3 decades: 1 to 10, 10 to 10/sup 2/, and 10/sup 2/ to 10/sup 3/ cps is presented. Electrica l energy is supplied by 6 volts given by 4 D type batteries. (INIS)

Regional Frequency Computation Users Manual.

DTIC Science & Technology

1972-07-01

increment of flow used to prevent infinite logarithms for events with zero flow X = Mean logarithm of flow events N = Total years of record S = Unbiased...C LIBRARY 3’jr.RfUTINFES USEO--ALflGpSINvAB3 1002 c PRGRAM ~ SUBRflUTINES CR0UTpR,chfNN-SFE COt’MENTS I-N RNGEN 100 C REFERENCE TOl TAPE ? AT

A new type of density-management diagram for slash pine plantations

Treesearch

Curtis L. VanderSchaaf

2006-01-01

Many Density-Management Diagrams (DMD) have been developed for conifer species throughout the world based on stand density index (SDI). The diagrams often plot the logarithm of average tree size (volume, weight, or quadratic mean diameter) over the logarithm of trees per unit area. A new type of DMD is presented for slash pine (Pinus elliottii var elliottii)...

MUTATIONAL AND TRANSCRIPTIONAL RESPONSES OF STATIONARY- AND LOGARITHMIC-PHASE SALMONELLA TO MX: CORRELATION OF MUTATIONAL RESPONSE TO CHANGES IN GENE EXPRESSION

EPA Science Inventory

We measured the mutational and transcriptional response of stationary-phase and logarithmic-phase S. typhimurium TA100 to 3 concentrations of the drinking water mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX). The mutagenicity of MX in strain TA100 was evaluated...

A numerical solution for two-dimensional Fredholm integral equations of the second kind with kernels of the logarithmic potential form

NASA Technical Reports Server (NTRS)

Gabrielsen, R. E.; Uenal, A.

1981-01-01

Two dimensional Fredholm integral equations with logarithmic potential kernels are numerically solved. The explicit consequence of these solutions to their true solutions is demonstrated. The results are based on a previous work in which numerical solutions were obtained for Fredholm integral equations of the second kind with continuous kernels.

Kinetics of drug release from ointments: Role of transient-boundary layer.

PubMed

Xu, Xiaoming; Al-Ghabeish, Manar; Krishnaiah, Yellela S R; Rahman, Ziyaur; Khan, Mansoor A

2015-10-15

In the current work, an in vitro release testing method suitable for ointment formulations was developed using acyclovir as a model drug. Release studies were carried out using enhancer cells on acyclovir ointments prepared with oleaginous, absorption, and water-soluble bases. Kinetics and mechanism of drug release was found to be highly dependent on the type of ointment bases. In oleaginous bases, drug release followed a unique logarithmic-time dependent profile; in both absorption and water-soluble bases, drug release exhibited linearity with respect to square root of time (Higuchi model) albeit differences in the overall release profile. To help understand the underlying cause of logarithmic-time dependency of drug release, a novel transient-boundary hypothesis was proposed, verified, and compared to Higuchi theory. Furthermore, impact of drug solubility (under various pH conditions) and temperature on drug release were assessed. Additionally, conditions under which deviations from logarithmic-time drug release kinetics occur were determined using in situ UV fiber-optics. Overall, the results suggest that for oleaginous ointments containing dispersed drug particles, kinetics and mechanism of drug release is controlled by expansion of transient boundary layer, and drug release increases linearly with respect to logarithmic time. Published by Elsevier B.V.

Uplink Downlink Rate Balancing and Throughput Scaling in FDD Massive MIMO Systems

NASA Astrophysics Data System (ADS)

Bergel, Itsik; Perets, Yona; Shamai, Shlomo

2016-05-01

In this work we extend the concept of uplink-downlink rate balancing to frequency division duplex (FDD) massive MIMO systems. We consider a base station with large number antennas serving many single antenna users. We first show that any unused capacity in the uplink can be traded off for higher throughput in the downlink in a system that uses either dirty paper (DP) coding or linear zero-forcing (ZF) precoding. We then also study the scaling of the system throughput with the number of antennas in cases of linear Beamforming (BF) Precoding, ZF Precoding, and DP coding. We show that the downlink throughput is proportional to the logarithm of the number of antennas. While, this logarithmic scaling is lower than the linear scaling of the rate in the uplink, it can still bring significant throughput gains. For example, we demonstrate through analysis and simulation that increasing the number of antennas from 4 to 128 will increase the throughput by more than a factor of 5. We also show that a logarithmic scaling of downlink throughput as a function of the number of receive antennas can be achieved even when the number of transmit antennas only increases logarithmically with the number of receive antennas.

On the geometry of mixed states and the Fisher information tensor

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

Contreras, I., E-mail: icontrer@illinois.edu; Ercolessi, E., E-mail: ercolessi@bo.infn.it; Schiavina, M., E-mail: michele.schiavina@math.uzh.ch

2016-06-15

In this paper, we will review the co-adjoint orbit formulation of finite dimensional quantum mechanics, and in this framework, we will interpret the notion of quantum Fisher information index (and metric). Following previous work of part of the authors, who introduced the definition of Fisher information tensor, we will show how its antisymmetric part is the pullback of the natural Kostant–Kirillov–Souriau symplectic form along some natural diffeomorphism. In order to do this, we will need to understand the symmetric logarithmic derivative as a proper 1-form, settling the issues about its very definition and explicit computation. Moreover, the fibration of co-adjointmore » orbits, seen as spaces of mixed states, is also discussed.« less

Color normalization for robust evaluation of microscopy images

NASA Astrophysics Data System (ADS)

Švihlík, Jan; Kybic, Jan; Habart, David

2015-09-01

This paper deals with color normalization of microscopy images of Langerhans islets in order to increase robustness of the islet segmentation to illumination changes. The main application is automatic quantitative evaluation of the islet parameters, useful for determining the feasibility of islet transplantation in diabetes. First, background illumination inhomogeneity is compensated and a preliminary foreground/background segmentation is performed. The color normalization itself is done in either lαβ or logarithmic RGB color spaces, by comparison with a reference image. The color-normalized images are segmented using color-based features and pixel-wise logistic regression, trained on manually labeled images. Finally, relevant statistics such as the total islet area are evaluated in order to determine the success likelihood of the transplantation.

Top++: A program for the calculation of the top-pair cross-section at hadron colliders

NASA Astrophysics Data System (ADS)

Czakon, Michał; Mitov, Alexander

2014-11-01

We present the program Top++ for the numerical evaluation of the total inclusive cross-section for producing top quark pairs at hadron colliders. The program calculates the cross-section in (a) fixed order approach with exact next-to-next-to leading order (NNLO) accuracy and (b) by including soft-gluon resummation for the hadronic cross-section in Mellin space with full next-to-next-to-leading logarithmic (NNLL) accuracy. The program offers the user significant flexibility through the large number (29) of available options. Top++ is written in C++. It has a very simple to use interface that is intuitive and directly reflects the physics. The running of the program requires no programming experience from the user.

Living with ghosts in Lorentz invariant theories

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

Garriga, Jaume; Vilenkin, Alexander, E-mail: jaume.garriga@ub.edu, E-mail: vilenkin@cosmos.phy.tufts.edu

2013-01-01

We argue that theories with ghosts may have a long lived vacuum state even if all interactions are Lorentz preserving. In space-time dimension D = 2, we consider the tree level decay rate of the vacuum into ghosts and ordinary particles mediated by non-derivative interactions, showing that this is finite and logarithmically growing in time. For D > 2, the decay rate is divergent unless we assume that the interaction between ordinary matter and the ghost sector is soft in the UV, so that it can be described in terms of non-local form factors rather than point-like vertices. We providemore » an example of a nonlocal gravitational-strength interaction between the two sectors, which appears to satisfy all observational constraints.« less

Empirical Models for the Shielding and Reflection of Jet Mixing Noise by a Surface

NASA Technical Reports Server (NTRS)

Brown, Cliff

2015-01-01

Empirical models for the shielding and refection of jet mixing noise by a nearby surface are described and the resulting models evaluated. The flow variables are used to non-dimensionalize the surface position variables, reducing the variable space and producing models that are linear function of non-dimensional surface position and logarithmic in Strouhal frequency. A separate set of coefficients are determined at each observer angle in the dataset and linear interpolation is used to for the intermediate observer angles. The shielding and rejection models are then combined with existing empirical models for the jet mixing and jet-surface interaction noise sources to produce predicted spectra for a jet operating near a surface. These predictions are then evaluated against experimental data.

Empirical Models for the Shielding and Reflection of Jet Mixing Noise by a Surface

NASA Technical Reports Server (NTRS)

Brown, Clifford A.

2016-01-01

Empirical models for the shielding and reflection of jet mixing noise by a nearby surface are described and the resulting models evaluated. The flow variables are used to non-dimensionalize the surface position variables, reducing the variable space and producing models that are linear function of non-dimensional surface position and logarithmic in Strouhal frequency. A separate set of coefficients are determined at each observer angle in the dataset and linear interpolation is used to for the intermediate observer angles. The shielding and reflection models are then combined with existing empirical models for the jet mixing and jet-surface interaction noise sources to produce predicted spectra for a jet operating near a surface. These predictions are then evaluated against experimental data.

Associated t t ¯ production at the LHC: Theoretical predictions at NLO +NNLL accuracy

NASA Astrophysics Data System (ADS)

Kulesza, Anna; Motyka, Leszek; Stebel, Tomasz; Theeuwes, Vincent

2018-06-01

We perform threshold resummation of soft gluon corrections to the total cross section and the invariant mass distribution for the process p p →t t ¯H . The resummation is carried out at next-to-next-to-leading-logarithmic (NNLL) accuracy using the direct QCD Mellin space technique in the three-particle invariant mass kinematics. After presenting analytical expressions we discuss the impact of resummation on the numerical predictions for the associated Higgs boson production with top quarks at the LHC. We find that next-to-leading-order (NLO)+NNLL resummation leads to predictions for which the central values are remarkably stable with respect to scale variation and for which theoretical uncertainties are reduced in comparison to NLO predictions.

Flame Spread and Group-Combustion Excitation in Randomly Distributed Droplet Clouds with Low-Volatility Fuel near the Excitation Limit: a Percolation Approach Based on Flame-Spread Characteristics in Microgravity

NASA Astrophysics Data System (ADS)

Mikami, Masato; Saputro, Herman; Seo, Takehiko; Oyagi, Hiroshi

2018-03-01

Stable operation of liquid-fueled combustors requires the group combustion of fuel spray. Our study employs a percolation approach to describe unsteady group-combustion excitation based on findings obtained from microgravity experiments on the flame spread of fuel droplets. We focus on droplet clouds distributed randomly in three-dimensional square lattices with a low-volatility fuel, such as n-decane in room-temperature air, where the pre-vaporization effect is negligible. We also focus on the flame spread in dilute droplet clouds near the group-combustion-excitation limit, where the droplet interactive effect is assumed negligible. The results show that the occurrence probability of group combustion sharply decreases with the increase in mean droplet spacing around a specific value, which is termed the critical mean droplet spacing. If the lattice size is at smallest about ten times as large as the flame-spread limit distance, the flame-spread characteristics are similar to those over an infinitely large cluster. The number density of unburned droplets remaining after completion of burning attained maximum around the critical mean droplet spacing. Therefore, the critical mean droplet spacing is a good index for stable combustion and unburned hydrocarbon. In the critical condition, the flame spreads through complicated paths, and thus the characteristic time scale of flame spread over droplet clouds has a very large value. The overall flame-spread rate of randomly distributed droplet clouds is almost the same as the flame-spread rate of a linear droplet array except over the flame-spread limit.

A Tale of “Two” Comets: The Primary Volatile Composition of Comet 2P/Encke Across Apparitions

NASA Astrophysics Data System (ADS)

Roth, Nathan X.; Gibb, Erika L.; Bonev, Boncho P.; DiSanti, Michael A.; Dello Russo, Neil; Vervack, Ronald J.; McKay, Adam J.; Kawakita, Hideyo

2017-10-01

2P/Encke is one of the most frequently observed comets in history, yet its highly favorable 2017 apparition allowed the first comprehensive comparison of primary volatile abundances in the same comet across multiple apparitions. It offered an opportunity to address pressing questions in cometary science, including investigating evolutionary and/or heliocentric distance effects on volatile production, sampling the hypervolatiles CO and CH4 in an ecliptic comet, and probing volatile release at small Rh (0.4 AU). The faint nature of ecliptic comets and low geocentric velocity during most apparitions make these observations in the near-infrared rare (in particular at small Rh) and of high scientific impact. On March 21, 22, and 25 we characterized the volatile composition of 2P post-perihelion using the high-resolution near-infrared iSHELL spectrograph at the 3 m NASA-IRTF on Maunakea, HI. We detected fluorescent emission from eight primary volatiles (H2O, CO, C2H6, CH3OH, CH4, H2CO, NH3, and HCN) and three secondary volatiles (OH*, NH2, and CN). Upper limits were derived for OCS and C2H2. We report rotational temperatures, production rates, and mixing ratios (with respect to H2O). Compared to median relative abundances in comets observed in the near-infrared to date, mixing ratios of trace gases in 2P/Encke are depleted for all detected species except HCN and NH3, which are consistent with the median. The detection of the hypervolatiles CO and CH4 is particularly notable given the paucity of measurements of these species in ecliptic comets. We observed significant differences in primary volatile composition compared to published pre-perihelion results from the 2003 apparition at larger Rh (~1.2 AU) (Radeva et al. 2013). We will discuss possible mechanisms for these effects, including asymmetry about perihelion in 2P (Sekanina 1988a, b), and discuss the results in the context of findings from the Rosetta mission and ground-based studies of comets. This work was supported by the NASA Earth and Space Science Fellowship, Solar Workings, Solar System Observations, and Astrobiology Programs, and NSF Solar and Planetary Science Grants.

Evaluation of data transformations used with the square root and schoolfield models for predicting bacterial growth rate.

PubMed Central

Alber, S A; Schaffner, D W

1992-01-01

A comparison was made between mathematical variations of the square root and Schoolfield models for predicting growth rate as a function of temperature. The statistical consequences of square root and natural logarithm transformations of growth rate use in several variations of the Schoolfield and square root models were examined. Growth rate variances of Yersinia enterocolitica in brain heart infusion broth increased as a function of temperature. The ability of the two data transformations to correct for the heterogeneity of variance was evaluated. A natural logarithm transformation of growth rate was more effective than a square root transformation at correcting for the heterogeneity of variance. The square root model was more accurate than the Schoolfield model when both models used natural logarithm transformation. PMID:1444367

A law of the iterated logarithm for Grenander’s estimator

PubMed Central

Dümbgen, Lutz; Wellner, Jon A.; Wolff, Malcolm

2016-01-01

In this note we prove the following law of the iterated logarithm for the Grenander estimator of a monotone decreasing density: If f(t0) > 0, f′(t0) < 0, and f′ is continuous in a neighborhood of t0, then lim supn→∞(n2log logn)1/3(fn^(t0)−f(t0))=|f(t0)f′(t0)/2|1/32Malmost surely where M≡supg∈GTg=(3/4)1/3andTg≡argmaxu{g(u)−u2};here G is the two-sided Strassen limit set on R. The proof relies on laws of the iterated logarithm for local empirical processes, Groeneboom’s switching relation, and properties of Strassen’s limit set analogous to distributional properties of Brownian motion. PMID:28042197

Fechner's law: where does the log transform come from?

PubMed

Laming, Donald

2010-01-01

This paper looks at Fechner's law in the light of 150 years of subsequent study. In combination with the normal, equal variance, signal-detection model, Fechner's law provides a numerically accurate account of discriminations between two separate stimuli, essentially because the logarithmic transform delivers a model for Weber's law. But it cannot be taken to be a measure of internal sensation because an equally accurate account is provided by a chi(2) model in which stimuli are scaled by their physical magnitude. The logarithmic transform of Fechner's law arises because, for the number of degrees of freedom typically required in the chi(2) model, the logarithm of a chi(2) variable is, to a good approximation, normal. This argument is set within a general theory of sensory discrimination.

Elastic scattering of virtual photons via a quark loop in the double-logarithmic approximation

NASA Astrophysics Data System (ADS)

Ermolaev, B. I.; Ivanov, D. Yu.; Troyan, S. I.

2018-04-01

We calculate the amplitude of elastic photon-photon scattering via a single quark loop in the double-logarithmic approximation, presuming all external photons to be off-shell and unpolarized. At the same time we account for the running coupling effects. We consider this process in the forward kinematics at arbitrary relations between t and the external photon virtualities. We obtain explicit expressions for the photon-photon scattering amplitudes in all double-logarithmic kinematic regions. Then we calculate the small-x asymptotics of the obtained amplitudes and compare them with the parent amplitudes, thereby fixing the applicability regions of the asymptotics, i.e., fixing the applicability region for the nonvacuum Reggeons. We find that these Reggeons should be used at x <10-8 only.

Atomic Oxygen Interactions With Silicone Contamination on Spacecraft in Low Earth Orbit Studied

NASA Technical Reports Server (NTRS)

Banks, Bruce A.

2001-01-01

Silicones have been widely used on spacecraft as potting compounds, adhesives, seals, gaskets, hydrophobic surfaces, and atomic oxygen protective coatings. Contamination of optical and thermal control surfaces on spacecraft in low Earth orbit (LEO) has been an ever-present problem as a result of the interaction of atomic oxygen with volatile species from silicones and hydrocarbons onboard spacecraft. These interactions can deposit a contaminant that is a risk to spacecraft performance because it can form an optically absorbing film on the surfaces of Sun sensors, star trackers, or optical components or can increase the solar absorptance of thermal control surfaces. The transmittance, absorptance, and reflectance of such contaminant films seem to vary widely from very transparent SiOx films to much more absorbing SiOx-based films that contain hydrocarbons. At the NASA Glenn Research Center, silicone contamination that was oxidized by atomic oxygen has been examined from LEO spacecraft (including the Long Duration Exposure Facility and the Mir space station solar arrays) and from ground laboratory LEO simulations. The findings resulted in the development of predictive models that may help explain the underlying issues and effects. Atomic oxygen interactions with silicone volatiles and mixtures of silicone and hydrocarbon volatiles produce glassy SiOx-based contaminant coatings. The addition of hydrocarbon volatiles in the presence of silicone volatiles appears to cause much more absorbing (and consequently less transmitting) contaminant films than when no hydrocarbon volatiles are present. On the basis of the LDEF and Mir results, conditions of high atomic oxygen flux relative to low contaminant flux appear to result in more transparent contaminant films than do conditions of low atomic oxygen flux with high contaminant flux. Modeling predictions indicate that the deposition of contaminant films early in a LEO flight should depend much more on atomic oxygen flux than it does later in a mission.

Subsurface Connections and Magma Mixing as revealed by Olivine- and Pyroxene-Hosted Melt Inclusions from Cerro Negro Volcano and the Las Pilas-El Hoyo Complex, Nicaragua.

NASA Astrophysics Data System (ADS)

Venugopal, S.; Moune, S.; Williams-Jones, G.

2015-12-01

Cerro Negro, the youngest volcano in the Central American Volcanic Belt, is a polygenetic cinder cone with relatively frequent explosive basaltic eruptions. Las Pilas, on the other hand, is a much larger and older complex with milder and less frequent eruptions. Based on historical data, these two closely spaced volcanoes have shown concurrent eruptive behavior, suggesting a subsurface connection. To further investigate this link, melt inclusions, which are blebs of melt trapped in growing crystals, were the obvious choice for optimal comparison of sources and determination of pre-eruptive volatile contents and magmatic conditions. Olivine-hosted inclusions were chosen for both volcanoes and pyroxene-hosted inclusions were also sampled from Las Pilas to represent the evolved melt. Major, volatile and trace elements reveal a distinct geochemical continuum with Cerro Negro defining the primitive end member and Las Pilas representing the evolved end member. Volatile contents are high for Cerro Negro (up to 1260 ppm CO2, 4.27 wt% H2O and 1700 ppm S) suggesting that volatile exsolution is likely the trigger for Cerro Negro's explosive eruptions. Las Pilas volatile contents are lower but consistent with degassing and evolutionary trends shown by major oxides. Trace element contents are rather unique and suggest Cerro Negro magmas fractionally crystallize while Las Pilas magmas are the products of mixing. Magmatic conditions were estimated with major and volatile contents: at least 2.4 kbar and 1170 °C for Cerro Negro melts and 1.3 kbar and 1130 °C for Las Pilas melts with an overall oxygen fugacity at the NNO buffer. In combination with available literature data, this study suggests an interconnected subsurface plumbing system and thus Cerro Negro should be considered as the newest vent within the Las Pilas-El Hoyo Complex.

Climatological Aspects of the Optical Properties of Fine/Coarse Mode Aerosol Mixtures

NASA Technical Reports Server (NTRS)

Eck, T. F.; Holben, B. N.; Sinyuk, A.; Pinker, R. T.; Goloub, P.; Chen, H.; Chatenet, B.; Li, Z.; Singh, R. P.; Tripathi, S.N.;

BASIC2 INTERPRETER; minimal basic language. [MCS-80,8080-based microcomputers; 8080 Assembly language

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

McGoldrick, P.R.; Allison, T.G.

The BASIC2 INTERPRETER was developed to provide a high-level easy-to-use language for performing both control and computational functions in the MCS-80. The package is supplied as two alternative implementations, hardware and software. The ''software'' implementation provides the following capabilities: entry and editing of BASIC programs, device-independent I/O, special functions to allow access from BASIC to any I/O port, formatted printing, special INPUT/OUTPUT-and-proceed statements to allow I/O without interrupting BASIC program execution, full arithmetic expressions, limited string manipulation (10 or fewer characters), shorthand forms for common BASIC keywords, immediate mode BASIC statement execution, and capability of running a BASIC program thatmore » is stored in PROM. The allowed arithmetic operations are addition, subtraction, multiplication, division, and raising a number to a positive integral power. In the second, or ''hardware'', implementation of BASIC2 requiring an Am9511 Arithmetic Processing Unit (APU) interfaced to the 8080 microprocessor, arithmetic operations are performed by the APU. The following additional built-in functions are available in this implementation: square root, sine, cosine, tangent, arcsine, arccosine, arctangent, exponential, logarithm base e, and logarithm base 10. MCS-80,8080-based microcomputers; 8080 Assembly language; Approximately 8K bytes of RAM to store the assembled interpreter, additional user program space, and necessary peripheral devices. The hardware implementation requires an Am9511 Arithmetic Processing Unit and an interface board (reference 2).« less

Biological basis for space-variant sensor design I: parameters of monkey and human spatial vision

NASA Astrophysics Data System (ADS)

Rojer, Alan S.; Schwartz, Eric L.

1991-02-01

Biological sensor design has long provided inspiration for sensor design in machine vision. However relatively little attention has been paid to the actual design parameters provided by biological systems as opposed to the general nature of biological vision architectures. In the present paper we will provide a review of current knowledge of primate spatial vision design parameters and will present recent experimental and modeling work from our lab which demonstrates that a numerical conformal mapping which is a refinement of our previous complex logarithmic model provides the best current summary of this feature of the primate visual system. In this paper we will review recent work from our laboratory which has characterized some of the spatial architectures of the primate visual system. In particular we will review experimental and modeling studies which indicate that: . The global spatial architecture of primate visual cortex is well summarized by a numerical conformal mapping whose simplest analytic approximation is the complex logarithm function . The columnar sub-structure of primate visual cortex can be well summarized by a model based on a band-pass filtered white noise. We will also refer to ongoing work in our lab which demonstrates that: . The joint columnar/map structure of primate visual cortex can be modeled and summarized in terms of a new algorithm the ''''proto-column'''' algorithm. This work provides a reference-point for current engineering approaches to novel architectures for

Modeling and Simulation of Viscous Electro-Active Polymers

PubMed Central

Vogel, Franziska; Göktepe, Serdar; Steinmann, Paul; Kuhl, Ellen

2014-01-01

Electro-active materials are capable of undergoing large deformation when stimulated by an electric field. They can be divided into electronic and ionic electro-active polymers (EAPs) depending on their actuation mechanism based on their composition. We consider electronic EAPs, for which attractive Coulomb forces or local re-orientation of polar groups cause a bulk deformation. Many of these materials exhibit pronounced visco-elastic behavior. Here we show the development and implementation of a constitutive model, which captures the influence of the electric field on the visco-elastic response within a geometrically non-linear finite element framework. The electric field affects not only the equilibrium part of the strain energy function, but also the viscous part. To adopt the familiar additive split of the strain from the small strain setting, we formulate the governing equations in the logarithmic strain space and additively decompose the logarithmic strain into elastic and viscous parts. We show that the incorporation of the electric field in the viscous response significantly alters the relaxation and hysteresis behavior of the model. Our parametric study demonstrates that the model is sensitive to the choice of the electro-viscous coupling parameters. We simulate several actuator structures to illustrate the performance of the method in typical relaxation and creep scenarios. Our model could serve as a design tool for micro-electro-mechanical systems, microfluidic devices, and stimuli-responsive gels such as artificial skin, tactile displays, or artificial muscle. PMID:25267881

RT-MATRIX: Measuring Total Organic Carbon by Photocatalytic Oxidation of Volatile Organic Compounds

NASA Technical Reports Server (NTRS)

2008-01-01

Volatile organic compounds (VOCs) inevitably accumulate in enclosed habitats such as the International Space Station and the Crew Exploration Vehicle (CEV) as a result of human metabolism, material off-gassing, and leaking equipment. Some VOCs can negatively affect the quality of the crew's life, health, and performance; and consequently, the success of the mission. Air quality must be closely monitored to ensure a safe living and working environment. Currently, there is no reliable air quality monitoring system that meets NASA's stringent requirements for power, mass, volume, or performance. The ultimate objective of the project -- the development of a Real-Time, Miniaturized, Autonomous Total Risk Indicator System (RT.MATRIX).is to provide a portable, dual-function sensing system that simultaneously determines total organic carbon (TOC) and individual contaminants in air streams.

Instabilities in large economies: aggregate volatility without idiosyncratic shocks

NASA Astrophysics Data System (ADS)

Bonart, Julius; Bouchaud, Jean-Philippe; Landier, Augustin; Thesmar, David

2014-10-01

We study a dynamical model of interconnected firms which allows for certain market imperfections and frictions, restricted here to be myopic price forecasts and slow adjustment of production. Whereas the standard rational equilibrium is still formally a stationary solution of the dynamics, we show that this equilibrium becomes linearly unstable in a whole region of parameter space. When agents attempt to reach the optimal production target too quickly, coordination breaks down and the dynamics becomes chaotic. In the unstable, ‘turbulent’ phase, the aggregate volatility of the total output remains substantial even when the amplitude of idiosyncratic shocks goes to zero or when the size of the economy becomes large. In other words, crises become endogenous. This suggests an interesting resolution of the ‘small shocks, large business cycles’ puzzle.

Window contamination on Expose-R

NASA Astrophysics Data System (ADS)

Demets, R.; Bertrand, M.; Bolkhovitinov, A.; Bryson, K.; Colas, C.; Cottin, H.; Dettmann, J.; Ehrenfreund, P.; Elsaesser, A.; Jaramillo, E.; Lebert, M.; van Papendrecht, G.; Pereira, C.; Rohr, T.; Saiagh, K.

2015-01-01

Expose is a multi-user instrument for astrobiological and astrochemical experiments in space. Installed at the outer surface of the International Space Station, it enables investigators to study the impact of the open space environment on biological and biochemical test samples. Two Expose missions have been completed so far, designated as Expose-E (Rabbow et al. 2012) and Expose-R (Rabbow et al. this issue). One of the space-unique environmental factors offered by Expose is full-spectrum, ultraviolet (UV)-rich electromagnetic radiation from the Sun. This paper describes and analyses how on Expose-R, access of the test samples to Solar radiation degraded during space exposure in an unpredicted way. Several windows in front of the Sun-exposed test samples acquired a brown shade, resulting in a reduced transparency in visible light, UV and vacuum UV (VUV). Post-flight investigations revealed the discolouration to be caused by a homogenous film of cross-linked organic polymers at the inside of the windows. The chemical signature varied per sample carrier. No such films were found on windows from sealed, pressurized compartments, or on windows that had been kept out of the Sun. This suggests that volatile compounds originating from the interior of the Expose facility were cross-linked and photo-fixed by Solar irradiation at the rear side of the windows. The origin of the volatiles was not fully identified; most probably there was a variety of sources involved including the biological test samples, adhesives, plastics and printed circuit boards. The outer surface of the windows (pointing into space) was chemically impacted as well, with a probable effect on the transparency in VUV. The reported analysis of the window contamination on Expose-R is expected to help the interpretation of the scientific results and offers possibilities to mitigate this problem on future missions - in particular Expose-R2, the direct successor of Expose-R.

Mars atmospheric loss to space: Observations of present-day loss and implications for long-term volatile evolution

NASA Astrophysics Data System (ADS)

Jakosky, Bruce; Brain, David; Luhmann, Janet; Grebowsky, Joe

2017-04-01

MAVEN completed its first Mars year of science mapping in October 2016. Results show loss of gas to space by multiple processes, including solar-wind pick-up, sputtering, photochemical loss, and thermal escape, along with their responses to changing solar and solar-wind boundary conditions and to discrete solar events. By understanding the current loss rates and the processes controlling them, we are able to examine the long-term loss to space, including the effects of different solar conditions early in history; in addition, we are able to use stable-isotope ratios to derive the integrated loss to space through time. Preliminary results suggest that loss to space was a dominant, if not the dominant, mechanism that drove the changing climate through time. We will present a framework for analyzing and interpreting the results, along with preliminary results on the extrapolation to long timescales.

A Bid Price Equation For Timber Sales on the Ouachita and Ozark National Forests

Treesearch

Michael M. Huebschmann; Thomas B. Lynch; David K. Lewis; Daniel S. Tilley; James M. Guldin

2004-01-01

Data from 150 timber sales on the Ouachita and Ozark National Forests in Arkansas and southeaster n Oklahoma were used to develop an equation that relates bid prices to timber sale variables. Variables used to predict the natural logarithm of the real, winning total bid price are the natural logarithms of total sawtimber volume per sale, total pulpwood volume per sale...

Approximating exponential and logarithmic functions using polynomial interpolation

NASA Astrophysics Data System (ADS)

Gordon, Sheldon P.; Yang, Yajun

2017-04-01

This article takes a closer look at the problem of approximating the exponential and logarithmic functions using polynomials. Either as an alternative to or a precursor to Taylor polynomial approximations at the precalculus level, interpolating polynomials are considered. A measure of error is given and the behaviour of the error function is analysed. The results of interpolating polynomials are compared with those of Taylor polynomials.

Linear and Logarithmic Speed-Accuracy Trade-Offs in Reciprocal Aiming Result from Task-Specific Parameterization of an Invariant Underlying Dynamics

ERIC Educational Resources Information Center

Bongers, Raoul M.; Fernandez, Laure; Bootsma, Reinoud J.

2009-01-01

The authors examined the origins of linear and logarithmic speed-accuracy trade-offs from a dynamic systems perspective on motor control. In each experiment, participants performed 2 reciprocal aiming tasks: (a) a velocity-constrained task in which movement time was imposed and accuracy had to be maximized, and (b) a distance-constrained task in…

Measurement of breakthrough volumes of volatile chemical warfare agents on a poly(2,6-diphenylphenylene oxide)-based adsorbent and application to thermal desorption-gas chromatography/mass spectrometric analysis.

PubMed

Kanamori-Kataoka, Mieko; Seto, Yasuo

2015-09-04

To establish adequate on-site solvent trapping of volatile chemical warfare agents (CWAs) from air samples, we measured the breakthrough volumes of CWAs on three adsorbent resins by an elution technique using direct electron ionization mass spectrometry. The trapping characteristics of Tenax(®) TA were better than those of Tenax(®) GR and Carboxen(®) 1016. The latter two adsorbents showed non-reproducible breakthrough behavior and low VX recovery. The specific breakthrough values were more than 44 (sarin) L/g Tenax(®) TA resin at 20°C. Logarithmic values of specific breakthrough volume for four nerve agents (sarin, soman, tabun, and VX) showed a nearly linear correlation with the reciprocals of their boiling points, but the data point of sulfur mustard deviated from this linear curve. Next, we developed a method to determine volatile CWAs in ambient air by thermal desorption-gas chromatography (TD-GC/MS). CWA solutions that were spiked into the Tenax TA(®) adsorbent tubes were analyzed by a two-stage TD-GC/MS using a Tenax(®) TA-packed cold trap tube. Linear calibration curves for CWAs retained in the resin tubes were obtained in the range between 0.2pL and 100pL for sarin, soman, tabun, cyclohexylsarin, and sulfur mustard; and between 2pL and 100pL for VX and Russian VX. We also examined the stability of CWAs in Tenax(®) TA tubes purged with either dry or 50% relative humidity air under storage conditions at room temperature or 4°C. More than 80% sarin, soman, tabun, cyclohexylsarin, and sulfur mustard were recovered from the tubes within 2 weeks. In contrast, the recoveries of VX and Russian VX drastically reduced with storage time at room temperature, resulting in a drop to 10-30% after 2 weeks. Moreover, we examined the trapping efficiency of Tenax TA(®) adsorbent tubes for vaporized CWA samples (100mL) prepared in a 500mL gas sampling cylinder. In the concentration range of 0.2-2.5mg/m(3), >50% of sarin, soman, tabun, cyclohexylsarin, and HD were recovered, whereas <1% of VX and Russian VX were recovered in the same concentration range. The results indicate that CWA vapors, with the exception of VX and Russian VX, can be measured by an on-site collection procedure using the Tenax(®) TA resin tubes, followed by a subsequent TD-GC/MS analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

KSC-04PD-0005

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. -- Lanfang Levine, with Dynamac Corp., helps install new equipment for gas chromatography and mass spectrometry in the Space Life Sciences Lab. The equipment will enable analysis of volatile compounds, such as from plants. The 100,000 square-foot facility houses labs for NASAs ongoing research efforts, microbiology/microbial ecology studies and analytical chemistry labs. Also calling the new lab home are facilities for space flight-experiment and flight-hardware development, new plant growth chambers, and an Orbiter Environment Simulator that will be used to conduct ground control experiments in simulated flight conditions for space flight experiments. The SLS Lab, formerly known as the Space Experiment Research and Processing Laboratory or SERPL, provides space for NASAs Life Sciences Services contractor Dynamac Corporation, Bionetics Corporation, and researchers from the University of Florida. NASAs Office of Biological and Physical Research will use the facility for processing life sciences experiments that will be conducted on the International Space Station. The SLS Lab is the magnet facility for the International Space Research Park at KSC being developed in partnership with Florida Space Authority.

Assessing the role of pavement macrotexture in preventing crashes on highways.

PubMed

Pulugurtha, Srinivas S; Kusam, Prasanna R; Patel, Kuvleshay J

2010-02-01

The objective of this article is to assess the role of pavement macrotexture in preventing crashes on highways in the State of North Carolina. Laser profilometer data obtained from the North Carolina Department of Transportation (NCDOT) for highways comprising four corridors are processed to calculate pavement macrotexture at 100-m (approximately 330-ft) sections according to the American Society for Testing and Materials (ASTM) standards. Crash data collected over the same lengths of the corridors were integrated with the calculated pavement macrotexture for each section. Scatterplots were generated to assess the role of pavement macrotexture on crashes and logarithm of crashes. Regression analyses were conducted by considering predictor variables such as million vehicle miles of travel (as a function of traffic volume and length), the number of interchanges, the number of at-grade intersections, the number of grade-separated interchanges, and the number of bridges, culverts, and overhead signs along with pavement macrotexture to study the statistical significance of relationship between pavement macrotexture and crashes (both linear and log-linear) when compared to other predictor variables. Scatterplots and regression analysis conducted indicate a more statistically significant relationship between pavement macrotexture and logarithm of crashes than between pavement macrotexture and crashes. The coefficient for pavement macrotexture, in general, is negative, indicating that the number of crashes or logarithm of crashes decreases as it increases. The relation between pavement macrotexture and logarithm of crashes is generally stronger than between most other predictor variables and crashes or logarithm of crashes. Based on results obtained, it can be concluded that maintaining pavement macrotexture greater than or equal to 1.524 mm (0.06 in.) as a threshold limit would possibly reduce crashes and provide safe transportation to road users on highways.

Virtual Machine Language Controls Remote Devices

NASA Technical Reports Server (NTRS)

2014-01-01

Kennedy Space Center worked with Blue Sun Enterprises, based in Boulder, Colorado, to enhance the company's virtual machine language (VML) to control the instruments on the Regolith and Environment Science and Oxygen and Lunar Volatiles Extraction mission. Now the NASA-improved VML is available for crewed and uncrewed spacecraft, and has potential applications on remote systems such as weather balloons, unmanned aerial vehicles, and submarines.

Reaction: Chemistry Driven by the Harsh Space Environment

NASA Technical Reports Server (NTRS)

Farrell, William M.

2018-01-01

The studies by Solar System Exploration Research Virtual Institute (SSERVI) teams such as REVEALS and DREAM2 not only connect back to the highest planetary science decadal goals regarding volatiles but also feed forward to understanding the chemical origins of potential resources at the surface useful for human exploration. See https://sservi.nasa.gov for more about SSERVI and its dynamic teams.

Narrative spaces between intractability outside the clinic.

PubMed

Wiederhold, Anna M

2014-01-01

In this essay, the author reflects on her experience conducting field research outside an abortion clinic amid volatile protests and counterprotests. She identifies moments of convergence in the oppositional groups' narrative explanations for participating in the weekly protests, and contemplates the possibilities for dialogue in these sorts of intractable conflicts. She concludes with reflections on communication scholars' roles in engaging with polarizing health narratives.

Beagle 2 the Moon: An Experimental Package to Measure Polar Ice and Volatiles in Permanently Shadowed Areas or Beneath the Lunar Surface

NASA Technical Reports Server (NTRS)

Gibson, E. K.; McKay, D. S.; Pillinger, C. T.; Wright, I. P.; Sims, M. R.; Richter, L.

2008-01-01

NASA has announced the selection of several Lunar Science Sortie Concept Studies for potential scientific payloads with future Lunar Missions. The Beagle 2 scientific package was one of those chosen for study. Near the beginning of the next decade will see the launch of scientific payloads to the lunar surface to begin laying the foundations for the return to the moon in the Vision for Space Exploration. Shortly thereafter, astronauts will return to the lunar surface with the ability to place scientific packages on the surface that will provide information about lunar resources and compositions of materials in permanently shadowed regions of the moon (1). One of the important questions which must be answered early in the program is whether there are lunar resources which would facilitate "living off the land" and not require the transport of resources and consumables from Earth (2). The Beagle science package developed to seek the signatures of life on Mars is the ideal payload (3) to use on the lunar surface for determining the nature of hydrogen, water and lunar volatiles found in the polar regions which could support the Vision for Space Exploration.

NASA Space Engineering Research Center for Utilization of Local Planetary Resources

NASA Technical Reports Server (NTRS)

Ramohalli, Kumar; Lewis, John S.

1991-01-01

In the processing of propellants, volatiles, and metals subject area, the following topics are discussed: reduction of lunar regolith; reduction of carbon dioxide; and reduction of carbonaceous materials. Other areas addressed include: (1) production of structural and refractory materials; (2) resource discovery and characterization; (3) system automation and optimization; and (4) database development. The majority of these topics are discussed with respect to the development of lunar and mars bases. Some main topics of interest include: asteroid resources, lunar resources, mars resources, materials processing, construction materials, propellant production, oxygen production, and space-based oxygen production plants.

An analog gamma correction scheme for high dynamic range CMOS logarithmic image sensors.

PubMed

Cao, Yuan; Pan, Xiaofang; Zhao, Xiaojin; Wu, Huisi

2014-12-15

In this paper, a novel analog gamma correction scheme with a logarithmic image sensor dedicated to minimize the quantization noise of the high dynamic applications is presented. The proposed implementation exploits a non-linear voltage-controlled-oscillator (VCO) based analog-to-digital converter (ADC) to perform the gamma correction during the analog-to-digital conversion. As a result, the quantization noise does not increase while the same high dynamic range of logarithmic image sensor is preserved. Moreover, by combining the gamma correction with the analog-to-digital conversion, the silicon area and overall power consumption can be greatly reduced. The proposed gamma correction scheme is validated by the reported simulation results and the experimental results measured for our designed test structure, which is fabricated with 0.35 μm standard complementary-metal-oxide-semiconductor (CMOS) process.

Path Loss Prediction Formula in Urban Area for the Fourth-Generation Mobile Communication Systems

NASA Astrophysics Data System (ADS)

Kitao, Koshiro; Ichitsubo, Shinichi

A site-general type prediction formula is created based on the measurement results in an urban area in Japan assuming that the prediction frequency range required for Fourth-Generation (4G) Mobile Communication Systems is from 3 to 6GHz, the distance range is 0.1 to 3km, and the base station (BS) height range is from 10 to 100m. Based on the measurement results, the path loss (dB) is found to be proportional to the logarithm of the distance (m), the logarithm of the BS height (m), and the logarithm of the frequency (GHz). Furthermore, we examine the extension of existing formulae such as the Okumura-Hata, Walfisch-Ikegami, and Sakagami formulae for 4G systems and propose a prediction formula based on the Extended Sakagami formula.

An Analog Gamma Correction Scheme for High Dynamic Range CMOS Logarithmic Image Sensors

PubMed Central

Cao, Yuan; Pan, Xiaofang; Zhao, Xiaojin; Wu, Huisi

2014-01-01

In this paper, a novel analog gamma correction scheme with a logarithmic image sensor dedicated to minimize the quantization noise of the high dynamic applications is presented. The proposed implementation exploits a non-linear voltage-controlled-oscillator (VCO) based analog-to-digital converter (ADC) to perform the gamma correction during the analog-to-digital conversion. As a result, the quantization noise does not increase while the same high dynamic range of logarithmic image sensor is preserved. Moreover, by combining the gamma correction with the analog-to-digital conversion, the silicon area and overall power consumption can be greatly reduced. The proposed gamma correction scheme is validated by the reported simulation results and the experimental results measured for our designed test structure, which is fabricated with 0.35 μm standard complementary-metal-oxide-semiconductor (CMOS) process. PMID:25517692