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Sample records for b-l model naturally

  1. Naturalness and dark matter in the supersymmetric B -L extension of the standard model

    NASA Astrophysics Data System (ADS)

    Delle Rose, Luigi; Khalil, Shaaban; King, Simon J. D.; Marzo, Carlo; Moretti, Stefano; Un, Cem S.

    2017-09-01

    We study the naturalness properties of the B -L supersymmetric standard model (BLSSM) with type-I seesaw and compare them to those of the minimal supersymmetric standard model (MSSM) at both low (i.e., Large Hadron Collider) energies and high (i.e., unification) scales. By adopting standard measures of naturalness, we assess that, in the presence of full unification of the additional gauge couplings and scalar/fermionic masses of the BLSSM, such a scenario reveals a somewhat higher degree of fine-tuning (FT) than the MSSM, when the latter is computed at the unification scale and all available theoretical and experimental constraints, but the dark matter (DM) ones, are taken into account. Yet, such a difference, driven primarily by the collider limits requiring a high mass for the gauge boson associated to the breaking of the additional U (1 )B -L gauge group of the BLSSM in addition to the S U (3 )C×S U (2 )L×U (1 )Y of the MSSM, should be regarded as a modest price to pay for the former in relation to the latter, if one notices that the nonminimal scenario offers a significant volume of parameter space where numerous DM solutions of different compositions can be found to the relic density constraints, unlike the case of the minimal structure, wherein only one type of solution is accessible over an ever diminishing parameter space. In fact, this different level of tension within the two SUSY models in complying with current data is well revealed when the FT measure is recomputed in terms of the low-energy spectra of the two models, over their allowed regions of parameter space now in the presence of all DM bounds, as it is shown that the tendency is now opposite, with the BLSSM appearing more natural than the MSSM.

  2. Dark matter in B-L extended MSSM models

    SciTech Connect

    Khalil, S.; Okada, H.

    2009-04-15

    We analyze the dark matter problem in the context of the supersymmetric U(1){sub B-L} model. In this model, the lightest neutralino can be the B-L gaugino Z-tilde{sub B-L} or the extra Higgsinos {chi}-tilde{sub 1,2} dominated. We compute the thermal relic abundance of these particles and show that, unlike the lightest neutralino in the MSSM, they can account for the observed relic abundance with no conflict with other phenomenological constraints. The prospects for their direct detection, if they are part of our galactic halo, are also discussed.

  3. Classically conformal radiative neutrino model with gauged B - L symmetry

    NASA Astrophysics Data System (ADS)

    Okada, Hiroshi; Orikasa, Yuta

    2016-09-01

    We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.

  4. Probing a classically conformal B -L model with gravitational waves

    NASA Astrophysics Data System (ADS)

    Jinno, Ryusuke; Takimoto, Masahiro

    2017-01-01

    We study the cosmological history of the classical conformal B -L gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. In particular, we consider the thermal phase transition of the U (1 )B -L symmetry in the early Universe and resulting gravitational wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) U (1 )B -L is broken after the reheating, (2) the B -L gauge coupling does not blow up below the Planck scale, and (3) the thermal phase transition completes in almost all the patches in the Universe, the gravitational wave spectrum can be as large as ΩGW˜10-8 at the frequency f ˜0.01 - 1 Hz for some model parameters, and a vast parameter region can be tested by future interferometer experiments.

  5. Electroweak vacuum stability in classically conformal B-L extension of the standard model

    NASA Astrophysics Data System (ADS)

    Das, Arindam; Okada, Nobuchika; Papapietro, Nathan

    2017-02-01

    We consider the minimal U(1)_{B-L} extension of the standard model (SM) with the classically conformal invariance, where an anomaly-free U(1)_{B-L} gauge symmetry is introduced along with three generations of right-handed neutrinos and a U(1)_{B-L} Higgs field. Because of the classically conformal symmetry, all dimensional parameters are forbidden. The B-L gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, generating the mass for the U(1)_{B-L} gauge boson (Z^' boson) and the right-handed neutrinos. Through a small negative coupling between the SM Higgs doublet and the B-L Higgs field, the negative mass term for the SM Higgs doublet is generated and the electroweak symmetry is broken. In this model context, we investigate the electroweak vacuum instability problem in the SM. It is well known that in the classically conformal U(1)_{B-L} extension of the SM, the electroweak vacuum remains unstable in the renormalization group analysis at the one-loop level. In this paper, we extend the analysis to the two-loop level, and perform parameter scans. We identify a parameter region which not only solve the vacuum instability problem, but also satisfy the recent ATLAS and CMS bounds from search for Z^' boson resonance at the LHC Run-2. Considering self-energy corrections to the SM Higgs doublet through the right-handed neutrinos and the Z^' boson, we derive the naturalness bound on the model parameters to realize the electroweak scale without fine-tunings.

  6. Electroweak vacuum stability in classically conformal B - L extension of the standard model

    DOE PAGES

    Das, Arindam; Okada, Nobuchika; Papapietro, Nathan

    2017-02-23

    Here, we consider the minimal U(1) B - L extension of the standard model (SM) with the classically conformal invariance, where an anomaly-free U(1) B - L gauge symme- try is introduced along with three generations of right-handed neutrinos and a U(1) B - L Higgs field. Because of the classi- cally conformal symmetry, all dimensional parameters are forbidden. The B - L gauge symmetry is radiatively bro- ken through the Coleman–Weinberg mechanism, generating the mass for the U(1)B - L gauge boson (Z' boson) and the right-handed neutrinos. Through a small negative coupling between themore » SM Higgs doublet and the B - L Higgs field, the negative mass term for the SM Higgs doublet is gener- ated and the electroweak symmetry is broken. We investigate the electroweak vacuum instability problem in the SM in this model context. It is well known that in the classically conformal U(1) B - L extension of the SM, the electroweak vacuum remains unstable in the renormalization group anal- ysis at the one-loop level. In this paper, we extend the anal- ysis to the two-loop level, and perform parameter scans. We also identify a parameter region which not only solve the vacuum instability problem, but also satisfy the recent ATLAS and CMS bounds from search for Z ' boson resonance at the LHC Run-2. Considering self-energy corrections to the SM Higgs doublet through the right-handed neutrinos and the Z ' boson, we derive the naturalness bound on the model parameters to realize the electroweak scale without fine-tunings.« less

  7. Dark Matter in Supersymmetric U(1){sub B-L} Model

    SciTech Connect

    Khalil, S.; Okada, H.

    2009-04-17

    We analyze the dark matter problem in the context of supersymmetric, U(1){sub B-L} model. In this model, the lightest neutalino can be B-L gaugino Z-tilde{sub B-L} or Higgsinos {chi}-tilde{sub 1,2} dominated. We examine the thermal relic abundance of these particles and discuss the prospects for their direct detection if they form part of our galactic halo.

  8. The minimal SUSY B - L model: simultaneous Wilson lines and string thresholds

    NASA Astrophysics Data System (ADS)

    Deen, Rehan; Ovrut, Burt A.; Purves, Austin

    2016-07-01

    In previous work, we presented a statistical scan over the soft supersymmetry breaking parameters of the minimal SUSY B - L model. For specificity of calculation, unification of the gauge parameters was enforced by allowing the two Z_3× Z_3 Wilson lines to have mass scales separated by approximately an order of magnitude. This introduced an additional "left-right" sector below the unification scale. In this paper, for three important reasons, we modify our previous analysis by demanding that the mass scales of the two Wilson lines be simultaneous and equal to an "average unification" mass < M U >. The present analysis is 1) more "natural" than the previous calculations, which were only valid in a very specific region of the Calabi-Yau moduli space, 2) the theory is conceptually simpler in that the left-right sector has been removed and 3) in the present analysis the lack of gauge unification is due to threshold effects — particularly heavy string thresholds, which we calculate statistically in detail. As in our previous work, the theory is renormalization group evolved from < M U > to the electroweak scale — being subjected, sequentially, to the requirement of radiative B - L and electroweak symmetry breaking, the present experimental lower bounds on the B - L vector boson and sparticle masses, as well as the lightest neutral Higgs mass of ˜125 GeV. The subspace of soft supersymmetry breaking masses that satisfies all such constraints is presented and shown to be substantial.

  9. Gauge B-L model with residual Z3 symmetry

    DOE PAGES

    Ma, Ernest; Pollard, Nicholas; Srivastava, Rahul; ...

    2016-09-07

    We study a gauge B–L extension of the standard model of quarks and leptons with unconventional charges for the singlet right-handed neutrinos, and extra singlet scalars, such that a residual Z3 symmetry remains after the spontaneous breaking of B–L. The phenomenological consequences of this scenario, including the possibility of long-lived self-interacting dark matter and Z' collider signatures is discussed. Lepton number L is a familiar concept. It is usually defined as a global U (1) symmetry, under which the leptons of the standard model (SM), i.e. e,μ,τ together with their neutrinos νe,νμ,ντ have L=1, and all other SM particles havemore » L=0. In the case of nonzero Majorana neutrino masses, this continuous symmetry is broken to a discrete Z2 symmetry, i.e. (-1)L or lepton parity. In this paper, we consider a gauge B–L extension of the SM, such that a residual Z3 symmetry remains after the spontaneous breaking of B–L. This is then a realization of the unusual notion of Z3 lepton symmetry. It has specific phenomenological consequences, including the possibility of a long-lived particle as a dark-matter candidate.« less

  10. Supersymmetric U(1)Y‧⊗ U(1)B-L extension of the Standard Model

    NASA Astrophysics Data System (ADS)

    Montero, J. C.; Pleitez, V.; Sánchez-Vega, B. L.; Rodriguez, M. C.

    2017-06-01

    We build a supersymmetric version with SU(3)C ⊗ SU(2)L ⊗ U(1)Y‧⊗ U(1)B-L gauge symmetry, where Y‧ is a new charge and B and L are the usual baryonic and leptonic numbers. The model has three right-handed neutrinos with identical B - L charges, and can accommodate all fermion masses at the tree level. In particular, the type I seesaw mechanism is implemented for the generation of the active neutrino masses. We obtain the mass spectra of all sectors and for the scalar one we also give the flat directions allowed by the model.

  11. Galactic gamma ray excess and dark matter phenomenology in a U(1) B- L model

    NASA Astrophysics Data System (ADS)

    Biswas, Anirban; Choubey, Sandhya; Khan, Sarif

    2016-08-01

    In this work, we have considered a gauged U(1)B-L extension of the Standard Model (SM) with three right handed neutrinos for anomaly cancellation and two additional SM singlet complex scalars with nontrivial B-L charges. One of these is used to spontaneously break the U(1)B-L gauge symmetry, leading to Majorana masses for the neutrinos through the standard Type I seesaw mechanism, while the other becomes the dark matter (DM) candidate in the model. We test the viability of the model to simultaneously explain the DM relic density observed in the CMB data as well as the Galactic Centre (GC) γ-ray excess seen by Fermi-LAT. We show that for DM masses in the range 40-55 GeV and for a wide range of U(1)B-L gauge boson masses, one can satisfy both these constraints if the additional neutral Higgs scalar has a mass around the resonance region. In studying the dark matter phenomenology and GC excess, we have taken into account theoretical as well as experimental constraints coming from vacuum stability condition, Planck bound on DM relic density, LHC and LUX and present allowed areas in the model parameter space consistent with all relevant data, calculate the predicted gamma ray flux from the GC and discuss the related phenomenology.

  12. Tree-level unitarity bounds for the minimal B-L model

    SciTech Connect

    Basso, L.; Belyaev, A.; Moretti, S.; Pruna, G. M.

    2010-05-01

    We have derived the unitarity bounds in the high energy limit for the minimal B-L extension of the standard model by analyzing the full class of Higgs and would-be Goldstone boson two-to-two scatterings at tree level. Moreover, we have investigated how these limits could vary at some lower critical value of the energy.

  13. Search for mono-Higgs signals at the LHC in the B -L supersymmetric standard model

    NASA Astrophysics Data System (ADS)

    Abdallah, W.; Hammad, A.; Khalil, S.; Moretti, S.

    2017-03-01

    We study mono-Higgs signatures emerging in the B -L supersymmetric standard model induced by new channels not present in the minimal supersymmetric standard model, i.e., via topologies in which the mediator is either a heavy Z', with mass of O (2 TeV ) , or an intermediate h' (the lightest C P -even Higgs state of B -L origin), with a mass of O (0.2 TeV ) . The mono-Higgs probe considered is the standard model-like Higgs state recently discovered at the Large Hadron Collider, so as to enforce its mass reconstruction for background reduction purposes. With this in mind, its two cleanest signatures are selected: γ γ and Z Z*→4 l (l =e , μ ). We show how both of these can be accessed with foreseen energy and luminosity options using a dedicated kinematic analysis performed in the presence of partonic, showering, hadronization and detector effects.

  14. Muon anomalous magnetic moment in SUSY B - L model with inverse seesaw

    NASA Astrophysics Data System (ADS)

    Khalil, Shaaban; Ün, Cem Salih

    2016-12-01

    Motivated by the tension between the Higgs mass and muon g - 2 in minimal supersymmetric standard model (MSSM), we analyze the muon g - 2 in supersymmetric B - L extension of the standard model (BLSSM) with inverse seesaw mechanism. In this model, the Higgs mass receives extra important radiative corrections proportional to large neutrino Yukawa coupling. We point out that muon g - 2 also gets significant contribution, due to the constructive interferences of light neutralino effects. The light neutralinos are typically the MSSM Bino like and the supersymmetric partner of U(1) B - L gauge boson (B˜‧-ino). We show that with universal soft supersymmetry breaking terms, the muon g - 2 resides within 2σ of the measured value, namely ∼ 20 ×10-10, with Higgs mass equal to 125 GeV.

  15. Resonant leptogenesis in the minimal B-L extended standard model at TeV

    SciTech Connect

    Iso, Satoshi; Orikasa, Yuta; Okada, Nobuchika

    2011-05-01

    We investigate the resonant leptogenesis scenario in the minimal B-L extended standard model with the B-L symmetry breaking at the TeV scale. Through detailed analysis of the Boltzmann equations, we show how much the resultant baryon asymmetry via leptogenesis is enhanced or suppressed, depending on the model parameters, in particular, the neutrino Dirac-Yukawa couplings and the TeV scale Majorana masses of heavy degenerate neutrinos. In order to consider a realistic case, we impose a simple ansatz for the model parameters and analyze the neutrino oscillation parameters and the baryon asymmetry via leptogenesis as a function of only a single CP phase. We find that for a fixed CP phase all neutrino oscillation data and the observed baryon asymmetry of the present Universe can be simultaneously reproduced.

  16. Atomki anomaly and dark matter in a radiative seesaw model with gauged B -L symmetry

    NASA Astrophysics Data System (ADS)

    Seto, Osamu; Shimomura, Takashi

    2017-05-01

    Motivated by recently reported anomalies in a decay of an excited state of beryllium by the Atomki Collaboration, we study a radiative seesaw model with gauged B -L symmetry and a Z2 parity. Assuming that the anomalies originate from the decay of the B -L gauge boson followed by the nuclear decay, the mass of the lightest right-handed neutrino or the dark matter candidate can be determined below 10 GeV. We show that for this mass range, the model can explain the anomalies in the beryllium decay and the relic dark matter abundance consistent with neutrino masses. We also predict its spin-independent cross section in direct detection experiments for this mass range.

  17. NLO+NLL collider bounds, Dirac fermion and scalar dark matter in the B-L model

    NASA Astrophysics Data System (ADS)

    Klasen, Michael; Lyonnet, Florian; Queiroz, Farinaldo S.

    2017-05-01

    Baryon and lepton numbers being accidental global symmetries of the Standard Model (SM), it is natural to promote them to local symmetries. However, to preserve anomaly-freedom, only combinations of B-L are viable. In this spirit, we investigate possible dark matter realizations in the context of the U(1)_B{-L} model: (i) Dirac fermion with unbroken B-L; (ii) Dirac fermion with broken B-L; (iii) scalar dark matter; (iv) two-component dark matter. We compute the relic abundance, direct and indirect detection observables and confront them with recent results from Planck, LUX-2016, and Fermi-LAT and prospects from XENON1T. In addition to the well-known LEP bound M_{Z^' }}/g_BL ≳ 7 TeV, we include often ignored LHC bounds using 13 TeV dilepton (dimuon + dielectron) data at next-to-leading order plus next-to-leading logarithmic accuracy. We show that, for gauge couplings smaller than 0.4, the LHC gives rise to the strongest collider limit. In particular, we find M_{Z^' }}/g_BL > 8.7 TeV for g_BL=0.3. We conclude that the NLO+NLL corrections improve the dilepton bounds on the Z^' } mass and that both dark matter candidates are only viable in the Z^' } resonance region, with the parameter space for scalar dark matter being fully probed by XENON1T. Lastly, we show that one can successfully have a minimal two-component dark matter model.

  18. Systematic U(1 ) B - L extensions of loop-induced neutrino mass models with dark matter

    NASA Astrophysics Data System (ADS)

    Ho, Shu-Yu; Toma, Takashi; Tsumura, Koji

    2016-08-01

    We study the gauged U(1 ) B - L extensions of the models for neutrino masses and dark matter. In this class of models, tiny neutrino masses are radiatively induced through the loop diagrams, while the origin of the dark matter stability is guaranteed by the remnant of the gauge symmetry. Depending on how the lepton number conservation is violated, these models are systematically classified. We present complete lists for the one-loop Z2 and the two-loop Z3 radiative seesaw models as examples of the classification. The anomaly cancellation conditions in these models are also discussed.

  19. Minimal flavor violation in the minimal U(1)B-L model and resonant leptogenesis

    NASA Astrophysics Data System (ADS)

    Okada, Nobuchika; Orikasa, Yuta; Yamada, Toshifumi

    2012-10-01

    We investigate the resonant leptogenesis scenario in the minimally U(1)B-L extended standard model with minimal flavor violation. In our model, the U(1)B-L gauge symmetry is broken at the TeV scale and standard model singlet neutrinos gain Majorana masses of order TeV. In addition, we introduce a flavor symmetry on the singlet neutrinos at a scale higher than TeV. The flavor symmetry is explicitly broken by the neutrino Dirac Yukawa coupling, which induces splittings in the singlet neutrino Majorana masses at lower scales through renormalization group evolutions. We call this setup minimal flavor violation. The mass splittings are proportional to the tiny Dirac Yukawa coupling, and hence they automatically enhance the CP asymmetry parameter necessary for the resonant leptogenesis mechanism. In this paper, we calculate the baryon number yield by solving the Boltzmann equations, including the effects of U(1)B-L gauge boson that also has TeV scale mass and causes washing-out of the singlet neutrinos in the course of thermal leptogenesis. The Dirac Yukawa coupling for neutrinos is fixed in terms of neutrino oscillation data and an arbitrary 3×3 complex-valued orthogonal matrix. We show that the right amount of baryon number asymmetry can be achieved through thermal leptogenesis in the context of the minimal flavor violation with singlet neutrinos and U(1)B-L gauge boson at the TeV scale. These particles can be discovered at the LHC in the near future.

  20. Phenomenology of the minimal B-L extension of the standard model: The Higgs sector

    SciTech Connect

    Basso, Lorenzo; Moretti, Stefano; Pruna, Giovanni Marco

    2011-03-01

    We investigate the phenomenology of the Higgs sector of the minimal B-L extension of the standard model. We present results for both the foreseen energy stages of the Large Hadron Collider ({radical}(s)=7 and 14 TeV). We show that in such a scenario several novel production and decay channels involving the two physical Higgs states could be accessed at such a machine. Amongst these, several Higgs signatures have very distinctive features with respect to those of other models with an enlarged Higgs sector, as they involve interactions of Higgs bosons between themselves, with Z{sup '} bosons as well as with heavy neutrinos.

  1. A heterotic standard model with B - L symmetry and a stable proton

    NASA Astrophysics Data System (ADS)

    Buchbinder, Evgeny I.; Constantin, Andrei; Lukas, Andre

    2014-06-01

    We consider heterotic Calabi-Yau compactifications with S(U(4) × U(1)) background gauge fields. These models lead to gauge groups with an additional U(1) factor which, under certain conditions, can combine with hypercharge to a B - L symmetry. The associated gauge boson is automatically super-massive and, hence, does not constitute a phenomenological problem. We illustrate this class of compactifications with a model based on the monad construction, which leads to a supersymmetric standard model with three families of quarks and leptons, one pair of Higgs doublets, three right-handed neutrinos and no exotics charged under the standard model group. The presence of the B - L symmetry means that the model is safe from proton decay induced by dimension four operators. Due to the presence of a special locus in moduli space where the bundle structure group is Abelian and the low-energy symmetry enhances we can also show the absence of dimension five proton-decay inducing operators.

  2. The Higgs sector of the minimal B- L model at future Linear Colliders

    NASA Astrophysics Data System (ADS)

    Basso, Lorenzo; Moretti, Stefano; Pruna, Giovanni Marco

    2011-08-01

    We investigate the phenomenology of the Higgs sector of the minimal B- L extension of the Standard Model at a future e + e - Linear Collider. We consider the discovery potential of both a sub-TeV and a multi-TeV machine. We show that, within such a theoretical scenario, several novel production and decay channels involving the two physical Higgs states, precluded at the LHC, could experimentally be accessed at such machines. Amongst these, several Higgs signatures have very distinctive features with respect to those of other models with enlarged Higgs sector, as they involve interactions of Higgs bosons between themselves, with Z' bosons as well as with heavy neutrinos. In particular, we present the scope of the Z' strahlung process for single and double Higgs production, the only suitable mechanism enabling one to access an almost decoupled heavy scalar state (therefore outside the LHC range).

  3. Renormalization group equation study of the scalar sector of the minimal B-L extension of the standard model

    SciTech Connect

    Basso, Lorenzo; Moretti, Stefano; Pruna, Giovanni Marco

    2010-09-01

    We present the complete set of renormalization group equations at one loop for the nonexotic minimal U(1) extension of the standard model (SM). It includes all models that are anomaly-free with the SM fermion content augmented by one right-handed neutrino per generation. We then pursue the numerical study of the pure B-L model, deriving the triviality and vacuum stability bounds on an enlarged scalar sector comprising one additional Higgs singlet field with respect to the SM.

  4. Mono-jet, -photon and - Z signals of a supersymmetric ( B - L) model at the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Abdallah, W.; Fiaschi, J.; Khalil, S.; Moretti, S.

    2016-02-01

    Search for invisible final states produced at the Large Hadron Collider (LHC) by new physics scenarios are normally carried out resorting to a variety of probes emerging from the initial state, in the form of single-jet, -photon and - Z boson signatures. These are particularly effective for models of Supersymmetry (SUSY) in presence of R-parity conservation, owing to the presence in their spectra of a stable neutralino as a Dark Matter (DM) candidate. We assume here as theoretical framework the Supersymmetric version of the ( B - L) extension of the Standard Model (BLSSM), wherein a mediator for invisible decays can be the Z ' boson present in this scenario. The peculiarity of the signal is thus that the final state objects carry a very large (transverse) missing energy, since the Z ' is naturally massive and constrained by direct searches and Electro-Weak Precision Tests (EWPTs) to be at least in the TeV scale region. Under these circumstances the efficiency in accessing the invisible final state and rejecting the Standard Model (SM) background is very high. This somehow compensates the rather meagre production rates. Another special feature of this invisible BLSSM signal is its composition, which is often dominated by sneutrino decays (alongside the more traditional neutrino and neutralino modes). Sensitivity of the CERN machine to these two features can therefore help disentangling the BLSSM from more popular SUSY models. We assess in this analysis the scope of the LHC in establishing the aforementioned invisible signals through a sophisticated signal-to-background simulation carried out in presence of parton shower, hadronisation as well as detector effects. We find that significant sensitivity exists already after 300 fb-1 during Run 2. We find that mono-jet events can be readily accessible at the LHC, so as to enable one to claim a prompt discovery, while mono-photon and - Z signals can be used as diagnostic tools of the underlying scenario.

  5. Search of New Higgs Boson in B-L Model at the LHC Using Monte Carlo Simulation

    NASA Astrophysics Data System (ADS)

    Mansour, H. M. M.; Bakhet, Nady

    The aim of this work is to search for a new heavy Higgs boson in the B-L extension of the Standard Model at LHC using the data produced from simulated collisions between two protons at different center of mass energies by Monte Carlo event generator programs to find new Higgs boson signatures at the LHC. Also we study the production and decay channels for Higgs boson in this model and its interactions with the other new particles of this model namely the new neutral gauge massive boson and the new fermionic right-handed heavy neutrinos .

  6. A model of the matter-antimatter asymmetry and cold dark matter with U(1)B - L ⊗ U(1)D

    NASA Astrophysics Data System (ADS)

    Yang, Wei-Min

    2016-11-01

    I suggest an effective model between the GUT and the electroweak scale. It only introduces the two symmetries of U(1) B - L and U(1)D besides the SM groups. The two symmetries are individually broken at the reheating temperature of the universe of 1012 GeV and the scale of 3 ∼ 4 TeV. The model can simultaneously accommodate the tiny neutrino masses, the matter-antimatter asymmetry and the cold dark matter (CDM). In particular, the model gives some interesting results and predictions, for instance, the neutrinos are of Dirac nature and their masses are related to the U(1)D breaking, the size of the matter-antimatter asymmetry is closely related to the mass hierarchy of the quarks and charged leptons, the CDM mass is probably in the range of 250 ∼ 350 GeV. Finally, it is feasible to test the model in future collider experiments.

  7. Phenomenology of the minimal B-L extension of the standard model: Z{sup '} and neutrinos

    SciTech Connect

    Basso, Lorenzo; Belyaev, Alexander; Moretti, Stefano; Shepherd-Themistocleous, Claire H.

    2009-09-01

    We present the Large Hadron Collider (LHC) discovery potential in the Z{sup '} and heavy neutrino sectors of a U(1){sub B-L} enlarged standard model also encompassing 3 heavy Majorana neutrinos. This model exhibits novel signatures at the LHC, the most interesting arising from a Z{sup '} decay chain involving heavy neutrinos, eventually decaying into leptons and jets. In particular, this signature allows one to measure the Z{sup '} and heavy neutrino masses involved. In addition, over a large region of the parameter space, the heavy neutrinos are rather long-lived particles producing distinctive displaced vertices that can be seen in the detectors. Lastly, the simultaneous measurement of both the heavy neutrino mass and decay length enables an estimate of the absolute mass of the parent light neutrino.

  8. A Model-Independent Search for the decay B->l nu gamma

    SciTech Connect

    Aubert, Bernard; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, David Nathan; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Osipenkov, I.L.; /more authors..

    2012-10-09

    The authors present a search for the radiative leptonic decay B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma}, where {ell} = e, {mu}, using a data sample of 465 million B{bar B} pairs collected by the BABAR experiment. In this analysis, they fully reconstruct the hadronic decay of one of the B mesons in {Upsilon}(4S) {yields} B{sup +}B{sup -} decays, then search for evidence of B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma} in the rest of the event. They observe no significant evidence of signal decays and report model-independent branching fraction upper limits of {Beta}(B{sup +} {yields} e{sup +}{nu}{sub e}{gamma}) < 17 x 10{sup -6}, {Beta}(B{sup +} {yields} {mu}{sup +}{nu}{sub {mu}}{gamma}) < 24 x 10{sup -6}, and {Beta}(B{sup +} {yields} {ell}{sup +}{nu}{sub {ell}}{gamma}) < 15.6 x 10{sup -6} ({ell} = e or {mu}), all at the 90% confidence level.

  9. Probing the Z' sector of the minimal B-L model at future Linear Colliders in the e+e- → μ+μ- process

    NASA Astrophysics Data System (ADS)

    Basso, L.; Belyaev, A.; Moretti, S.; Pruna, G. M.

    2009-10-01

    We study the capabilities of future electron-positron Linear Colliders, with centre-of-mass energy at the TeV scale, in accessing the parameter space of a Z' boson within the minimal B-L model. In such a model, wherein the Standard Model gauge group is augmented by a broken U(1)B-L symmetry - with B(L) being the baryon(lepton) number — the emerging Z' mass is expected to be in the above energy range. We carry out a detailed comparison between the discovery regions mapped over a two-dimensional configuration space (Z' mass and coupling) at the Large Hadron Collider and possible future Linear Colliders for the case of di-muon production. As known in the literature for other Z' models, we confirm that leptonic machines, as compared to the CERN hadronic accelerator, display an additional potential in discovering a B-L Z' boson as well as in allowing one to study its properties at a level of precision well beyond that of any of the existing colliders.

  10. Nonzero {theta}{sub 13} for neutrino mixing in a supersymmetric B-L gauge model with T{sub 7} lepton flavor symmetry

    SciTech Connect

    Cao Qinghong; Khalil, Shaaban; Ma, Ernest; Okada, Hiroshi

    2011-10-01

    We discuss how {theta}{sub 13}{ne}0 is accommodated in a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry T{sub 7} in the context of a supersymmetric extension of the standard model with gauged U(1){sub B-L}. We predict a correlation between {theta}{sub 13} and {theta}{sub 23}, as well as the effective neutrino mass m{sub ee} in neutrinoless double beta decay.

  11. Dirac or Inverse Seesaw Neutrino Masses from Gauged B - L Symmetry

    NASA Astrophysics Data System (ADS)

    Ma, Ernest; Srivastava, Rahul

    The gauged B - L symmetry is one of the simplest and well studied extension of standard model. In the conventional case, addition of three singlet right-handed neutrinos each transforming as -1 under the B - L symmetry renders it anomaly free. It is usually assumed that the B - L symmetry is spontaneously broken by a singlet scalar having two units of B - L charge, resulting in a natural implementation of Majorana seesaw mechanism for neutrinos. However, as we discuss in this proceeding, there is another simple anomaly free solution which leads to Dirac or inverse seesaw masses for neutrinos. These new possibilities are explored along with an application to neutrino mixing with S3 flavour symmetry.

  12. B-L mediated SUSY breaking with radiative B-L symmetry breaking

    SciTech Connect

    Kikuchi, Tatsuru; Kubo, Takayuki

    2008-11-23

    We explore a mechanism of radiative B-L symmetry breaking in analogous to the radiative electroweak symmetry breaking. The breaking scale of B-L symmetry is related to the neutrino masses through the see-saw mechanism. Once we incorporate the U(1){sub B-L} gauge symmetry in SUSY models, the U(1){sub B-L} gaugino, Z-tilde{sub B-L} appears, and it can mediate the SUSY breaking (Z-prime mediated SUSY breaking) at around the scale of 10{sup 6} GeV. Then we find a links between the neutrino mass (more precisly the see-saw or B-L scale of order 10{sup 6} GeV) and the Z-prime mediated SUSY breaking scale. It is also very interesting that the gluino at the weak scale becomes relatively light, and almost compressed mass spectra for the gaugino sector can be realized in this scenario, which is very interesting in scope of the LHC.

  13. Sneutrino inflation in supersymmetric B - L with inverse seesaw

    SciTech Connect

    Khalil, Shaaban; Sil, Arunansu

    2012-07-27

    We have shown that inflation in the supersymmetric B - L extension of the Standard Model can be realized where one of the associated right-handed sneutrinos can provide a non-trivial inflationary trajectory at tree level (hence breaking B - L during inflation). As soon as the inflation ends, the right-handed sneutrino falls into the supersymmetric vacuum, with a vanishing vacuum expectation value, so that B - L symmetry is restored. The B - L gauge symmetry will be radiatively broken at a TeV scale and light neutrino masses are generated through the inverse seesaw mechanism.

  14. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  15. Modeling Natural Selection

    ERIC Educational Resources Information Center

    Bogiages, Christopher A.; Lotter, Christine

    2011-01-01

    In their research, scientists generate, test, and modify scientific models. These models can be shared with others and demonstrate a scientist's understanding of how the natural world works. Similarly, students can generate and modify models to gain a better understanding of the content, process, and nature of science (Kenyon, Schwarz, and Hug…

  16. Inflection-point B -L Higgs inflation

    NASA Astrophysics Data System (ADS)

    Okada, Nobuchika; Raut, Digesh

    2017-02-01

    Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its initial value below the Planck mass (ϕI≲MPl). In order for a renormalization group (RG) improved effective λ ϕ4 potential to develop an inflection point, the quartic coupling λ (ϕ ) must exhibit a minimum with an almost vanishing value in its RG evolution, namely λ (ϕI)≃0 and βλ(ϕI)≃0 , where βλ is the beta function of the quartic coupling. As an example, we consider the minimal gauged B -L extended Standard Model at the TeV scale, where we identify the B -L Higgs field as the inflaton field. For a successful inflection-point inflation, which is consistent with the current cosmological observations, the mass ratios among the Z' gauge boson, the right-handed neutrinos and the B -L Higgs boson are fixed. Our scenario can be tested in the future collider experiments such as the high-luminosity LHC and the SHiP experiments. In addition, the inflection-point inflation provides a unique prediction for the running of the spectral index α ≃-2.7 ×10-3(60/N) 2 (N is the e -folding number), which can be tested in the near future.

  17. B-L violating proton decay modes and new baryogenesis scenario in SO(10).

    PubMed

    Babu, K S; Mohapatra, R N

    2012-08-31

    We show that grand unified theories based on SO(10) generate quite naturally baryon number violating dimension seven operators that violate B-L, and lead to novel nucleon decay modes such as n→e(-)K(+), e(-)π(+) and p→νπ(+). We find that in two-step breaking schemes of nonsupersymmetric SO(10), the partial lifetimes for these modes can be within reach of experiments. The interactions responsible for these decay modes also provide a new way to understand the origin of matter in the Universe via the decays of grand unified theory (GUT) scale scalar bosons of SO(10). Their (B-L)-violating nature guarantees that the GUT scale induced baryon asymmetry is not washed out by the electroweak sphaleron interactions. In minimal SO(10) models this asymmetry is closely tied to the masses of quarks, leptons and the neutrinos.

  18. The gravitational wave spectrum from cosmological B-L breaking

    SciTech Connect

    Buchmüller, W.; Domcke, V.; Kamada, K.; Schmitz, K. E-mail: valerie.domcke@desy.de E-mail: kai.schmitz@ipmu.jp

    2013-10-01

    Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying Ω{sub GW}h{sup 2} ∼ 10{sup −13}–10{sup −8}, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, BBO and DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

  19. The gravitational wave spectrum from cosmological B-L breaking

    NASA Astrophysics Data System (ADS)

    Buchmüller, W.; Domcke, V.; Kamada, K.; Schmitz, K.

    2013-10-01

    Cosmological B-L breaking is a natural and testable mechanism to generate the initial conditions of the hot early universe. If B-L is broken at the grand unification scale, the false vacuum phase drives hybrid inflation, ending in tachyonic preheating. The decays of heavy B-L Higgs bosons and heavy neutrinos generate entropy, baryon asymmetry and dark matter and also control the reheating temperature. The different phases in the transition from inflation to the radiation dominated phase produce a characteristic spectrum of gravitational waves. We calculate the complete gravitational wave spectrum due to inflation, preheating and cosmic strings, which turns out to have several features. The production of gravitational waves from cosmic strings has large uncertainties, with lower and upper bounds provided by Abelian Higgs strings and Nambu-Goto strings, implying ΩGWh2 ~ 10-13-10-8, much larger than the spectral amplitude predicted by inflation. Forthcoming gravitational wave detectors such as eLISA, advanced LIGO, ET, BBO and DECIGO will reach the sensitivity needed to test the predictions from cosmological B-L breaking.

  20. Natural language modeling

    SciTech Connect

    Sharp, J.K.

    1997-11-01

    This seminar describes a process and methodology that uses structured natural language to enable the construction of precise information requirements directly from users, experts, and managers. The main focus of this natural language approach is to create the precise information requirements and to do it in such a way that the business and technical experts are fully accountable for the results. These requirements can then be implemented using appropriate tools and technology. This requirement set is also a universal learning tool because it has all of the knowledge that is needed to understand a particular process (e.g., expense vouchers, project management, budget reviews, tax, laws, machine function).

  1. Majorana dark matter with B+L gauge symmetry

    NASA Astrophysics Data System (ADS)

    Chao, Wei; Guo, Huai-Ke; Zhang, Yongchao

    2017-04-01

    We present a new model that extends the Standard Model (SM) with the local B + L symmetry, and point out that the lightest new fermion ζ, introduced to cancel anomalies and stabilized automatically by the B + L symmetry, can serve as the cold dark matter candidate. We study constraints on the model from Higgs measurements, electroweak precision measurements as well as the relic density and direct detections of the dark matter. Numerical results reveal that the pseudo-vector coupling of ζ with Z and the Yukawa coupling with the SM Higgs are highly constrained by the latest results of LUX, while there are viable parameter space that could satisfy all the constraints and give testable predictions.

  2. Majorana dark matter with B+L gauge symmetry

    DOE PAGES

    Chao, Wei; Guo, Huai-Ke; Zhang, Yongchao

    2017-04-07

    Here, we present a new model that extends the Standard Model (SM) with the local B + L symmetry, and point out that the lightest new fermion, introduced to cancel anomalies and stabilized automatically by the B + L symmetry, can serve as the cold dark matter candidate. We also study constraints on the model from Higgs measurements, electroweak precision measurements as well as the relic density and direct detections of the dark matter. Our numerical results reveal that the pseudo-vector coupling of with Z and the Yukawa coupling with the SM Higgs are highly constrained by the latest resultsmore » of LUX, while there are viable parameter space that could satisfy all the constraints and give testable predictions.« less

  3. Natural Poincare gauge model

    SciTech Connect

    Aldrovandi, R.; Pereira, J.G.

    1986-05-15

    Because it acts on space-time and is not semisimple, the Poincare group cannot lead to a gauge theory of the usual kind. A candidate model is discussed which keeps itself as close as possible to the typical gauge scheme. Its field equations are the Yang-Mills equations for the Poincare group. It is shown that there exists no Lagrangian for these equations.

  4. Chaotic hybrid inflation with a gauged B -L

    NASA Astrophysics Data System (ADS)

    Carpenter, Linda M.; Raby, Stuart

    2014-11-01

    In this paper we present a novel formulation of chaotic hybrid inflation in supergravity. The model includes a waterfall field which spontaneously breaks a gauged U1 (B- L) at a GUT scale. This allows for the possibility of future model building which includes the standard formulation of baryogenesis via leptogenesis with the waterfall field decaying into right-handed neutrinos. We have not considered the following issues in this short paper, i.e. supersymmetry breaking, dark matter or the gravitino or moduli problems. Our focus is on showing the compatibility of the present model with Planck, WMAP and Bicep2 data.

  5. Modeling Natural Variation through Distribution

    ERIC Educational Resources Information Center

    Lehrer, Richard; Schauble, Leona

    2004-01-01

    This design study tracks the development of student thinking about natural variation as late elementary grade students learned about distribution in the context of modeling plant growth at the population level. The data-modeling approach assisted children in coordinating their understanding of particular cases with an evolving notion of data as an…

  6. Modeling Natural Variation through Distribution

    ERIC Educational Resources Information Center

    Lehrer, Richard; Schauble, Leona

    2004-01-01

    This design study tracks the development of student thinking about natural variation as late elementary grade students learned about distribution in the context of modeling plant growth at the population level. The data-modeling approach assisted children in coordinating their understanding of particular cases with an evolving notion of data as an…

  7. Modeling natural gas reservoirs: A simple model

    USGS Publications Warehouse

    Collier, Richard S.; Monash, E.A.

    1981-01-01

    A mathematical model is developed and tested for the production of natural gas with water encroachment and gas entrapment. The model is built on the material and volumetric balance relations, the Schilthuis water drive model, and a gas entrapment mechanism which assumes that the rate of gas entrapment is proportional to the volumetric rate of water influx. This model represents an alternative to the large grid models because of its low computer, maintenance, and manpower costs.

  8. TeV-scale gauged B-L symmetry with inverse seesaw mechanism

    SciTech Connect

    Khalil, Shaaban

    2010-10-01

    We propose a modified version of the TeV-scale B-L extension of the standard model, where neutrino masses are generated through the inverse seesaw mechanism. We show that heavy neutrinos in this model can be accessible via clean signals at the LHC. The search for the extra gauge boson Z{sub B-L}{sup '} through the decay into dileptons or two dileptons plus missing energy is studied. We also show that the B-L extra Higgs boson can be directly probed at the LHC via a clean dilepton and missing energy signal.

  9. Right-handed neutrino dark matter under the B - L gauge interaction

    NASA Astrophysics Data System (ADS)

    Kaneta, Kunio; Kang, Zhaofeng; Lee, Hye-Sung

    2017-02-01

    We study the right-handed neutrino (RHN) dark matter candidate in the minimal U(1) B-L gauge extension of the standard model. The U(1) B-L gauge symmetry offers three RHNs which can address the origin of the neutrino mass, the relic dark matter, and the matter-antimatter asymmetry of the universe. The lightest among the three is taken as the dark matter candidate, which is under the B - L gauge interaction. We investigate various scenarios for this dark matter candidate with the correct relic density by means of the freeze-out or freeze-in mechanism. A viable RHN dark matter mass lies in a wide range including keV to TeV scale. We emphasize the sub-electroweak scale light B - L gauge boson case, and identify the parameter region motivated from the dark matter physics, which can be tested with the planned experiments including the CERN SHiP experiment.

  10. Sterile neutrino dark matter with gauged U(1){sub B-L} and a low reheating temperature

    SciTech Connect

    Khalil, Shaaban; Seto, Osamu

    2009-04-17

    Sterile right-handed neutrinos can be naturally embedded in a low scale gauged U(1){sub B-L} extension of the standard model. We show that, within a low reheating scenario, such a neutrino can be produced via a novel manner, namely scattering through Z' gauge boson, and becomes an interesting dark matter candidate. In addition, we show that if the neutrino mass is of the order of MeV, then it accounts for the measured dark matter relic density and also accommodates the observed flux of 511 keV photons from the galactic bulge.

  11. Leptogenesis with conservation of B-L

    NASA Astrophysics Data System (ADS)

    Gonzalez-Garcia, M. C.; Racker, J.; Rius, N.

    2012-08-01

    We study leptogenesis in the decay of heavy Standard Model singlet fermions which carry lepton number, in a framework without Majorana masses above the electroweak scale. Based on M. C. Gonzalez-Garcia, J. Racker, N. Rius, JHEP 11 (2009) 079.

  12. The mass spectra, hierarchy and cosmology of B-L MSSM heterotic compactifications

    DOE PAGES

    Ambroso, Michael; Ovrut, Burt A.

    2011-04-10

    The matter spectrum of the MSSM, including three right-handed neutrino supermultiplets and one pair of Higgs-Higgs conjugate superfields, can be obtained by compactifying the E₈ x E₈ heterotic string and M-theory on Calabi-Yau manifolds with specific SU(4) vector bundles. These theories have the standard model gauge group augmented by an additional gauged U(1)B-L. Their minimal content requires that the B-L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed neutrino. In previous papers, we presented the results of a quasi-analytic renormalization group analysis showing that B-L gauge symmetry is indeed radiatively broken with anmore » appropriate B-L/electroweak hierarchy. In this paper, we extend these results by 1) enlarging the initial parameter space and 2) explicitly calculating all renormalization group equations numerically. The regions of the initial parameter space leading to realistic vacua are presented and the B-L/electroweak hierarchy computed over these regimes. At representative points, the mass spectrum for all particles and Higgs fields is calculated and shown to be consistent with present experimental bounds. Some fundamental phenomenological signatures of a non-zero right-handed neutrino expectation value are discussed, particularly the cosmology and proton lifetime arising from induced lepton and baryon number violating interactions.« less

  13. The mass spectra, hierarchy and cosmology of B-L MSSM heterotic compactifications

    SciTech Connect

    Ambroso, Michael; Ovrut, Burt A.

    2011-04-10

    The matter spectrum of the MSSM, including three right-handed neutrino supermultiplets and one pair of Higgs-Higgs conjugate superfields, can be obtained by compactifying the E₈ x E₈ heterotic string and M-theory on Calabi-Yau manifolds with specific SU(4) vector bundles. These theories have the standard model gauge group augmented by an additional gauged U(1)B-L. Their minimal content requires that the B-L gauge symmetry be spontaneously broken by a vacuum expectation value of at least one right-handed neutrino. In previous papers, we presented the results of a quasi-analytic renormalization group analysis showing that B-L gauge symmetry is indeed radiatively broken with an appropriate B-L/electroweak hierarchy. In this paper, we extend these results by 1) enlarging the initial parameter space and 2) explicitly calculating all renormalization group equations numerically. The regions of the initial parameter space leading to realistic vacua are presented and the B-L/electroweak hierarchy computed over these regimes. At representative points, the mass spectrum for all particles and Higgs fields is calculated and shown to be consistent with present experimental bounds. Some fundamental phenomenological signatures of a non-zero right-handed neutrino expectation value are discussed, particularly the cosmology and proton lifetime arising from induced lepton and baryon number violating interactions.

  14. Unification and mass spectrum in a B-L extended MSSM

    SciTech Connect

    Hernandez-Pinto, R. J.; Perez-Lorenzana, A.

    2009-04-20

    The simplest B-L extension of the minimum supersymmetric standard model (MSSM) may change some of the conceptions about the path for gauge unification as well as to affect the predicted spectrum of the supersymmetric particles at low energy. We present our results for the running of gauge coupling constants and mass parameter in this context.

  15. Student learning using the natural selection model

    NASA Astrophysics Data System (ADS)

    Mesmer, Karen Luann

    Students often have difficulty in learning natural selection, a major model in biology. This study examines what middle school students are capable of learning when taught about natural selection using a modeling approach. Students were taught the natural selection model including the components of population, variation, selective advantage, survival, heredity and reproduction. They then used the model to solve three case studies. Their learning was evaluated from responses on a pretest, a posttest and interviews. The results suggest that middle school students can identify components of the natural selection model in a Darwinian explanation, explain the significance of the components and relate them to each other as well as solve evolutionary problems using the model.

  16. Chromo-natural model in anisotropic background

    SciTech Connect

    Maleknejad, Azadeh; Erfani, Encieh E-mail: eerfani@ipm.ir

    2014-03-01

    In this work we study the chromo-natural inflation model in the anisotropic setup. Initiating inflation from Bianchi type-I cosmology, we analyze the system thoroughly during the slow-roll inflation, from both analytical and numerical points of view. We show that the isotropic FRW inflation is an attractor of the system. In other words, anisotropies are damped within few e-folds and the chromo-natural model respects the cosmic no-hair conjecture. Furthermore, we demonstrate that in the slow-roll limit, the anisotropies in both chromo-natural and gauge-flation models share the same dynamics.

  17. Construction and immunogenicity of human papillomavirus type 6b L1 recombinant plasmid.

    PubMed

    Liu, Fang; Wang, Jia-bi; Zuo, Ya-gang; Liu, Yue-hua; Ma, Dong-lai

    2004-09-01

    To construct a DNA vaccine as a prophylactic model to prevent condyloma acuminatum and detect its immunogenicity in mice. The major capsid protein (L1) gene of human papillomavirus (HPV) 6b was inserted into an eukaryotic expression plasmid (pcDNA3.1). The recombinant plasmid was transfected into COS-7 cells. Western blot were performed to detect whether L1 protein can be expressed in eukaryotic cells. Eighteen female BALB/c mice were tested for immunogenicity study. The recombinant plasmid (pcDNA3.1-HPV6bL1) was verified as HPV6b L1 gene by sequencing. Western blot showed specific strip. Anti-L1 protein antibodies could be detected in the mice's sera inoculated with pcDNA3.1-HPV6bL1. Similarly, IL-4, IL-2, and IFN-gamma were increased in the same mice. HPV6b L1 recombinant plasmid was constructed successfully which had immunogenicity for BALB/c mice. It provided experimental evidence for the research of DNA vaccine of condyloma acuminata.

  18. Modelling with words: Narrative and natural selection.

    PubMed

    Dimech, Dominic K

    2017-02-18

    I argue that verbal models should be included in a philosophical account of the scientific practice of modelling. Weisberg (2013) has directly opposed this thesis on the grounds that verbal structures, if they are used in science, only merely describe models. I look at examples from Darwin's On the Origin of Species (1859) of verbally constructed narratives that I claim model the general phenomenon of evolution by natural selection. In each of the cases I look at, a particular scenario is described that involves at least some fictitious elements but represents the salient causal components of natural selection. I pronounce the importance of prioritising observation of scientific practice for the philosophy of modelling and I suggest that there are other likely model types that are excluded from philosophical accounts.

  19. Computational models of natural language processing

    SciTech Connect

    Bara, B.G.; Guida, G.

    1984-01-01

    The main concern in this work is the illustration of models for natural language processing, and the discussion of their role in the development of computational studies of language. Topics covered include the following: competence and performance in the design of natural language systems; planning and understanding speech acts by interpersonal games; a framework for integrating syntax and semantics; knowledge representation and natural language: extending the expressive power of proposition nodes; viewing parsing as word sense discrimination: a connectionist approach; a propositional language for text representation; from topic and focus of a sentence to linking in a text; language generation by computer; understanding the Chinese language; semantic primitives or meaning postulates: mental models of propositional representations; narrative complexity based on summarization algorithms; using focus to constrain language generation; and towards an integral model of language competence.

  20. Learning generative models of natural images.

    PubMed

    Wu, Jiann-Ming; Lin, Zheng-Han

    2002-04-01

    This work proposes an unsupervised learning process for analysis of natural images. The derivation is based on a generative model, a stochastic coin-flip process directly operating on many disjoint multivariate Gaussian distributions. Following the maximal likelihood principle and using the Potts encoding, the goodness-of-fit of the generative model to tremendous patches randomly sampled from natural images is quantitatively expressed by an objective function subject to a set of constraints. By further combination of the objective function and the minimal wiring criterion, we achieve a mixed integer and linear programming. A hybrid of the mean field annealing and the gradient descent method is applied to the mathematical framework and produces three sets of interactive dynamics for the learning process. Numerical simulations show that the learning process is effective for extraction of orientation, localization and bandpass features and the generative model can make an ensemble of a sparse code for natural images.

  1. International Natural Gas Model 2011, Model Documentation Report

    EIA Publications

    2013-01-01

    This report documents the objectives, analytical approach and development of the International Natural Gas Model (INGM). It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  2. World Energy Projection System Plus Model Documentation: Natural Gas Model

    EIA Publications

    2011-01-01

    This report documents the objectives, analytical approach and development of the World Energy Projection System Plus (WEPS ) Natural Gas Model. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  3. International Natural Gas Model 2011, Model Documentation Report

    EIA Publications

    2013-01-01

    This report documents the objectives, analytical approach and development of the International Natural Gas Model (INGM). It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  4. Modular learning models in forecasting natural phenomena.

    PubMed

    Solomatine, D P; Siek, M B

    2006-03-01

    Modular model is a particular type of committee machine and is comprised of a set of specialized (local) models each of which is responsible for a particular region of the input space, and may be trained on a subset of training set. Many algorithms for allocating such regions to local models typically do this in automatic fashion. In forecasting natural processes, however, domain experts want to bring in more knowledge into such allocation, and to have certain control over the choice of models. This paper presents a number of approaches to building modular models based on various types of splits of training set and combining the models' outputs (hard splits, statistically and deterministically driven soft combinations of models, 'fuzzy committees', etc.). An issue of including a domain expert into the modeling process is also discussed, and new algorithms in the class of model trees (piece-wise linear modular regression models) are presented. Comparison of the algorithms based on modular local modeling to the more traditional 'global' learning models on a number of benchmark tests and river flow forecasting problems shows their higher accuracy and transparency of the resulting models.

  5. Homophyly/Kinship Model: Naturally Evolving Networks

    PubMed Central

    Li, Angsheng; Li, Jiankou; Pan, Yicheng; Yin, Xianchen; Yong, Xi

    2015-01-01

    It has been a challenge to understand the formation and roles of social groups or natural communities in the evolution of species, societies and real world networks. Here, we propose the hypothesis that homophyly/kinship is the intrinsic mechanism of natural communities, introduce the notion of the affinity exponent and propose the homophyly/kinship model of networks. We demonstrate that the networks of our model satisfy a number of topological, probabilistic and combinatorial properties and, in particular, that the robustness and stability of natural communities increase as the affinity exponent increases and that the reciprocity of the networks in our model decreases as the affinity exponent increases. We show that both homophyly/kinship and reciprocity are essential to the emergence of cooperation in evolutionary games and that the homophyly/kinship and reciprocity determined by the appropriate affinity exponent guarantee the emergence of cooperation in evolutionary games, verifying Darwin’s proposal that kinship and reciprocity are the means of individual fitness. We propose the new principle of structure entropy minimisation for detecting natural communities of networks and verify the functional module property and characteristic properties by a healthy tissue cell network, a citation network, some metabolic networks and a protein interaction network. PMID:26478264

  6. Homophyly/Kinship Model: Naturally Evolving Networks

    NASA Astrophysics Data System (ADS)

    Li, Angsheng; Li, Jiankou; Pan, Yicheng; Yin, Xianchen; Yong, Xi

    2015-10-01

    It has been a challenge to understand the formation and roles of social groups or natural communities in the evolution of species, societies and real world networks. Here, we propose the hypothesis that homophyly/kinship is the intrinsic mechanism of natural communities, introduce the notion of the affinity exponent and propose the homophyly/kinship model of networks. We demonstrate that the networks of our model satisfy a number of topological, probabilistic and combinatorial properties and, in particular, that the robustness and stability of natural communities increase as the affinity exponent increases and that the reciprocity of the networks in our model decreases as the affinity exponent increases. We show that both homophyly/kinship and reciprocity are essential to the emergence of cooperation in evolutionary games and that the homophyly/kinship and reciprocity determined by the appropriate affinity exponent guarantee the emergence of cooperation in evolutionary games, verifying Darwin’s proposal that kinship and reciprocity are the means of individual fitness. We propose the new principle of structure entropy minimisation for detecting natural communities of networks and verify the functional module property and characteristic properties by a healthy tissue cell network, a citation network, some metabolic networks and a protein interaction network.

  7. Homophyly/Kinship Model: Naturally Evolving Networks.

    PubMed

    Li, Angsheng; Li, Jiankou; Pan, Yicheng; Yin, Xianchen; Yong, Xi

    2015-10-19

    It has been a challenge to understand the formation and roles of social groups or natural communities in the evolution of species, societies and real world networks. Here, we propose the hypothesis that homophyly/kinship is the intrinsic mechanism of natural communities, introduce the notion of the affinity exponent and propose the homophyly/kinship model of networks. We demonstrate that the networks of our model satisfy a number of topological, probabilistic and combinatorial properties and, in particular, that the robustness and stability of natural communities increase as the affinity exponent increases and that the reciprocity of the networks in our model decreases as the affinity exponent increases. We show that both homophyly/kinship and reciprocity are essential to the emergence of cooperation in evolutionary games and that the homophyly/kinship and reciprocity determined by the appropriate affinity exponent guarantee the emergence of cooperation in evolutionary games, verifying Darwin's proposal that kinship and reciprocity are the means of individual fitness. We propose the new principle of structure entropy minimisation for detecting natural communities of networks and verify the functional module property and characteristic properties by a healthy tissue cell network, a citation network, some metabolic networks and a protein interaction network.

  8. Modeling Natural Killer Cell Targeted Immunotherapies

    PubMed Central

    Lopez-Lastra, Silvia; Di Santo, James P.

    2017-01-01

    Animal models have extensively contributed to our understanding of human immunobiology and to uncover the underlying pathological mechanisms occurring in the development of diseases. However, mouse models do not reproduce the genetic and molecular complexity inherent in human disease conditions. Human immune system (HIS) mouse models that are susceptible to human pathogens and can recapitulate human hematopoiesis and tumor immunobiology provide one means to bridge the interspecies gap. Natural killer cells are the founding member of the innate lymphoid cell family. They exert a rapid and strong immune response against tumor and pathogen-infected cells. Their antitumor features have long been exploited for therapeutic purposes in the context of cancer. In this review, we detail the development of highly immunodeficient mouse strains and the models currently used in cancer research. We summarize the latest improvements in adoptive natural killer (NK) cell therapies and the development of novel NK cell sources. Finally, we discuss the advantages of HIS mice to study the interactions between human NK cells and human cancers and to develop new therapeutic strategies. PMID:28405194

  9. Understanding requirements via natural language information modeling

    SciTech Connect

    Sharp, J.K.; Becker, S.D.

    1993-07-01

    Information system requirements that are expressed as simple English sentences provide a clear understanding of what is needed between system specifiers, administrators, users, and developers of information systems. The approach used to develop the requirements is the Natural-language Information Analysis Methodology (NIAM). NIAM allows the processes, events, and business rules to be modeled using natural language. The natural language presentation enables the people who deal with the business issues that are to be supported by the information system to describe exactly the system requirements that designers and developers will implement. Computer prattle is completely eliminated from the requirements discussion. An example is presented that is based upon a section of a DOE Order involving nuclear materials management. Where possible, the section is analyzed to specify the process(es) to be done, the event(s) that start the process, and the business rules that are to be followed during the process. Examples, including constraints, are developed. The presentation steps through the modeling process and shows where the section of the DOE Order needs clarification, extensions or interpretations that could provide a more complete and accurate specification.

  10. Understanding requirements via natural language information modeling

    SciTech Connect

    Sharp, J.K.; Becker, S.D.

    1993-12-31

    Information system requirements that are expressed as simple English sentences provide a clear understanding of what is needed between system specifiers, administrators, users, and developers of information systems. The approach used to develop the requirements is the Natural-language Information Analysis Methodology (NIAM). NIAM allows the processes, events, and business rules to be modeled using natural language. The natural language presentation enables the people who deal with the business issues that are to be supported by the information system to describe exactly the system requirements that designers and developers will implement. Computer prattle is completely eliminated from the requirements discussion. An example will be presented that is based upon a section of a DOE Order involving nuclear materials management. Where possible, the section will be analyzed to specify the process(es) to be done, the event(s) that start the process, and the business rules that are to be followed during the process. Examples, including constraints, will be developed. The presentation will step through the modeling process and show where the section of the DOE Order needs clarification, extensions or interpretations that could provide a more complete and accurate specification.

  11. Modelling natural and artificial hands with synergies

    PubMed Central

    Bicchi, Antonio; Gabiccini, Marco; Santello, Marco

    2011-01-01

    We report on recent work in modelling the process of grasping and active touch by natural and artificial hands. Starting from observations made in human hands about the correlation of degrees of freedom in patterns of more frequent use (postural synergies), we consider the implications of a geometrical model accounting for such data, which is applicable to the pre-grasping phase occurring when shaping the hand before actual contact with the grasped object. To extend applicability of the synergy model to study force distribution in the actual grasp, we introduce a modified model including the mechanical compliance of the hand's musculotendinous system. Numerical results obtained by this model indicate that the same principal synergies observed from pre-grasp postural data are also fundamental in achieving proper grasp force distribution. To illustrate the concept of synergies in the dual domain of haptic sensing, we provide a review of models of how the complexity and heterogeneity of sensory information from touch can be harnessed in simplified, tractable abstractions. These abstractions are amenable to fast processing to enable quick reflexes as well as elaboration of high-level percepts. Applications of the synergy model to the design and control of artificial hands and tactile sensors are illustrated. PMID:21969697

  12. Modelling natural and artificial hands with synergies.

    PubMed

    Bicchi, Antonio; Gabiccini, Marco; Santello, Marco

    2011-11-12

    We report on recent work in modelling the process of grasping and active touch by natural and artificial hands. Starting from observations made in human hands about the correlation of degrees of freedom in patterns of more frequent use (postural synergies), we consider the implications of a geometrical model accounting for such data, which is applicable to the pre-grasping phase occurring when shaping the hand before actual contact with the grasped object. To extend applicability of the synergy model to study force distribution in the actual grasp, we introduce a modified model including the mechanical compliance of the hand's musculotendinous system. Numerical results obtained by this model indicate that the same principal synergies observed from pre-grasp postural data are also fundamental in achieving proper grasp force distribution. To illustrate the concept of synergies in the dual domain of haptic sensing, we provide a review of models of how the complexity and heterogeneity of sensory information from touch can be harnessed in simplified, tractable abstractions. These abstractions are amenable to fast processing to enable quick reflexes as well as elaboration of high-level percepts. Applications of the synergy model to the design and control of artificial hands and tactile sensors are illustrated.

  13. Giant natural fluctuation models and anthropogenic warming

    NASA Astrophysics Data System (ADS)

    Lovejoy, S.; Rio Amador, L.; Hébert, R.; Lima, I.

    2016-08-01

    Explanations for the industrial epoch warming are polarized around the hypotheses of anthropogenic warming (AW) and giant natural fluctuations (GNFs). While climate sceptics have systematically attacked AW, up until now they have only invoked GNFs. This has now changed with the publication by D. Keenan of a sample of 1000 series from stochastic processes purporting to emulate the global annual temperature since 1880. While Keenan's objective was to criticize the International Panel on Climate Change's trend uncertainty analysis (their assumption that residuals are only weakly correlated), for the first time it is possible to compare a stochastic GNF model with real data. Using Haar fluctuations, probability distributions, and other techniques of time series analysis, we show that his model has unrealistically strong low-frequency variability so that even mild extrapolations imply ice ages every ≈1000 years. Helped by statistics, the GNF model can easily be scientifically rejected.

  14. Dog models of naturally occurring cancer.

    PubMed

    Rowell, Jennie L; McCarthy, Donna O; Alvarez, Carlos E

    2011-07-01

    Studies using dogs provide an ideal solution to the gap in animal models for natural disease and translational medicine. This is evidenced by approximately 400 inherited disorders being characterized in domesticated dogs, most of which are relevant to humans. There are several hundred isolated populations of dogs (breeds) and each has a vastly reduced genetic variation compared with humans; this simplifies disease mapping and pharmacogenomics. Dogs age five- to eight-fold faster than do humans, share environments with their owners, are usually kept until old age and receive a high level of health care. Farseeing investigators recognized this potential and, over the past decade, have developed the necessary tools and infrastructure to utilize this powerful model of human disease, including the sequencing of the dog genome in 2005. Here, we review the nascent convergence of genetic and translational canine models of spontaneous disease, focusing on cancer.

  15. Structural equation modeling and natural systems

    USGS Publications Warehouse

    Grace, James B.

    2006-01-01

    This book, first published in 2006, presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems.

  16. Flood Impact Modelling and Natural Flood Management

    NASA Astrophysics Data System (ADS)

    Owen, Gareth; Quinn, Paul; ODonnell, Greg

    2016-04-01

    Local implementation of Natural Flood Management methods are now being proposed in many flood schemes. In principal it offers a cost effective solution to a number of catchment based problem as NFM tackles both flood risk and WFD issues. However within larger catchments there is the issue of which subcatchments to target first and how much NFM to implement. If each catchment has its own configuration of subcatchment and rivers how can the issues of flood synchronisation and strategic investment be addressed? In this study we will show two key aspects to resolving these issues. Firstly, a multi-scale network water level recorder is placed throughout the system to capture the flow concentration and travel time operating in the catchment being studied. The second is a Flood Impact Model (FIM), which is a subcatchment based model that can generate runoff in any location using any hydrological model. The key aspect to the model is that it has a function to represent the impact of NFM in any subcatchment and the ability to route that flood wave to the outfall. This function allows a realistic representation of the synchronisation issues for that catchment. By running the model in interactive mode the user can define an appropriate scheme that minimises or removes the risk of synchornisation and gives confidence that the NFM investment is having a good level of impact downstream in large flood events.

  17. Nature of packs used in propellant modeling.

    PubMed

    Maggi, F; Stafford, S; Jackson, T L; Buckmaster, J

    2008-04-01

    In recent years we have constructed closely packed spheres using the Lubachevsky-Stillinger algorithm to generate morphological models of heterogeneous solid propellants. Improvements to the algorithm now allow us to create large polydisperse packs on a laptop computer, and to create monodisperse packs with packing fractions greater than 70% which display significant crystal order. The use of these models in the physical context motivates efforts to examine in some detail the nature of the packs, including certain statistical properties. We compare packing fractions for binary packs with long-known experimental data. Also, we discuss the near-neighbor number and the radial distribution function (RDF) for monodisperse packs and make comparisons with experimental data. We also briefly discuss the RDF for bidisperse packs. We also consider bounded monodisperse packs, and pay particular attention to the near-wall structure where we identify significant order.

  18. Virtual Research Environments for Natural Hazard Modelling

    NASA Astrophysics Data System (ADS)

    Napier, Hazel; Aldridge, Tim

    2017-04-01

    The Natural Hazards Partnership (NHP) is a group of 17 collaborating public sector organisations providing a mechanism for co-ordinated advice to government and agencies responsible for civil contingency and emergency response during natural hazard events. The NHP has set up a Hazard Impact Model (HIM) group tasked with modelling the impact of a range of UK hazards with the aim of delivery of consistent hazard and impact information. The HIM group consists of 7 partners initially concentrating on modelling the socio-economic impact of 3 key hazards - surface water flooding, land instability and high winds. HIM group partners share scientific expertise and data within their specific areas of interest including hydrological modelling, meteorology, engineering geology, GIS, data delivery, and modelling of socio-economic impacts. Activity within the NHP relies on effective collaboration between partners distributed across the UK. The NHP are acting as a use case study for a new Virtual Research Environment (VRE) being developed by the EVER-EST project (European Virtual Environment for Research - Earth Science Themes: a solution). The VRE is allowing the NHP to explore novel ways of cooperation including improved capabilities for e-collaboration, e-research, automation of processes and e-learning. Collaboration tools are complemented by the adoption of Research Objects, semantically rich aggregations of resources enabling the creation of uniquely identified digital artefacts resulting in reusable science and research. Application of the Research Object concept to HIM development facilitates collaboration, by encapsulating scientific knowledge in a shareable format that can be easily shared and used by partners working on the same model but within their areas of expertise. This paper describes the application of the VRE to the NHP use case study. It outlines the challenges associated with distributed partnership working and how they are being addressed in the VRE. A case

  19. Modeling Regional Economic Impacts of Natural Disasters

    NASA Astrophysics Data System (ADS)

    Boissonnade, A.; Hallegate, S.; Muir-Wood, R.; Schlumberger, M.; Onur, T.

    2007-05-01

    Common features of natural disasters are intense regional impacts and the need for assessing their economic impacts on the construction sectors. The years 2004 and 2005 were record-setting time for natural disasters with major disasters or catastrophic (Cat) events all around the world with dramatic consequences in human lives and economic losses around the world, affecting developed and developing countries. Although there is a large body of literature on assessing the impact of cat events, there is little available research on the quantification and modeling of the regional economic impact of such events on the cost and length of reconstruction. Current available econometric models have serious limitations because they need detailed information for modeling the complex interactions between the different stakeholders of the economy at a regional level that is generally not available. Also, very little research was performed for quantifying the demand surge, defined as the sudden increase in the cost of repairs due to amplified payments, following a hurricane or a series of hurricane events or other natural disasters. Demand surge is an important component of the overall economic impact of cat events and there is a need to better quantify it. This paper presents results of a research program that started after the 2004 and 2005 U.S. hurricane seasons. A large data set of economic and observed losses resulting from the hurricanes that affected Florida and the Gulf states in the US was collected at county level. This provided us with the basis for assessing the change in repair costs before and after these historical events, to quantify the demand surge (after removing the underlying baseline trends) at several dozens of locations across the areas affected, and to provide information on how the changes in demand surge vary spatially and temporally in affected areas for which the amount of structure losses were reported. A parallel research effort was undertaken for

  20. Fractal modeling of natural fracture networks

    SciTech Connect

    Ferer, M.; Dean, B.; Mick, C.

    1995-06-01

    West Virginia University will implement procedures for a fractal analysis of fractures in reservoirs. This procedure will be applied to fracture networks in outcrops and to fractures intersecting horizontal boreholes. The parameters resulting from this analysis will be used to generate synthetic fracture networks with the same fractal characteristics as the real networks. Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little a priori information. In the sections following, the authors will (1) present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using the fractal analysis over a stochastic analysis; and (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  1. Neurocysticercosis: A natural human model of epileptogenesis

    PubMed Central

    Nash, T.E.; Mahanty, S.; Loeb, J.A.; Theodore, W.H.; Friedman, A.; Sander, J.W.; Singh, E. G.; Cavalheiro, E.; Del Brutto, O.H.; Takayanagui, O.; Fleury, A.; Verastegui, M.; Preux, PM.; Montano, E.J.S.; Pretell, E.J.; White, A.C.; Gonzales, A. E.; Gilman, R.H.; Garcia, H.H.

    2014-01-01

    Objective To develop a better understanding on mechanisms of seizures and long-term epileptogenesis caused by neurocysticercosis. Methods A workshop was held bringing together experts in epilepsy and epileptogenesis and neurocysticercosis Results Human neurocysticercosis and parallel animal models offer a unique opportunity to understand basic mechanisms of seizures. Inflammatory responses to degenerating forms and in later stage calcified parasite granulomas are associated with seizures and epilepsy. Other mechanisms may also be involved in epileptogenesis as well. Conclusions Naturally occurring brain infections with neurocysticercosis offer a unique opportunity to develop treatments for one of the world’s most common causes of epilepsy and for the development of more general anti-epileptogenic treatments. Key advantages stem from the time course where an acute seizure heralds a start of the epileptogenic process and radiographic changes of calcification and perilesional edema provide biomarkers of a chronic epileptic state. PMID:25534640

  2. In the Footsteps of Nature: Nature Therapy as an Emerging Therapeutic-Educational Model.

    ERIC Educational Resources Information Center

    Berger, Ronen

    2003-01-01

    Basic principles of the nature therapy model are described, integrating the author's personal journey and examples from fieldwork and theory. Four aspects are nature as "sacred space"; nature as therapeutic setting; healing potential of nature's physical and aesthetic elements and connections to "universal truths"; and…

  3. In the Footsteps of Nature: Nature Therapy as an Emerging Therapeutic-Educational Model.

    ERIC Educational Resources Information Center

    Berger, Ronen

    2003-01-01

    Basic principles of the nature therapy model are described, integrating the author's personal journey and examples from fieldwork and theory. Four aspects are nature as "sacred space"; nature as therapeutic setting; healing potential of nature's physical and aesthetic elements and connections to "universal truths"; and…

  4. Modeling Recognition Memory Using the Similarity Structure of Natural Input

    ERIC Educational Resources Information Center

    Lacroix, Joyca P. W.; Murre, Jaap M. J.; Postma, Eric O.; van den Herik, H. Jaap

    2006-01-01

    The natural input memory (NAM) model is a new model for recognition memory that operates on natural visual input. A biologically informed perceptual preprocessing method takes local samples (eye fixations) from a natural image and translates these into a feature-vector representation. During recognition, the model compares incoming preprocessed…

  5. Modeling Recognition Memory Using the Similarity Structure of Natural Input

    ERIC Educational Resources Information Center

    Lacroix, Joyca P. W.; Murre, Jaap M. J.; Postma, Eric O.; van den Herik, H. Jaap

    2006-01-01

    The natural input memory (NAM) model is a new model for recognition memory that operates on natural visual input. A biologically informed perceptual preprocessing method takes local samples (eye fixations) from a natural image and translates these into a feature-vector representation. During recognition, the model compares incoming preprocessed…

  6. The Nature and Structure of Scientific Models. Working Paper.

    ERIC Educational Resources Information Center

    Cartier, Jennifer; Rudolph, John; Stewart, Jim

    This paper explores the nature and structure of scientific models by taking the position that representations are not models themselves. Representations of models are essential tools for communicating and conversing about the scientific models underlying them. A scientific model is considered to be a set of ideas that describe a natural process. A…

  7. B →XSl+l- in the minimal gauged (B -L ) supersymmetry

    NASA Astrophysics Data System (ADS)

    Feng, Tai-Fu; Yang, Jin-Lei; Zhang, Hai-Bin; Zhao, Shu-Min; Zhu, Rong-Fei

    2016-12-01

    Applying the effective Hamilton for b →s l+l- , (l =e ,μ ) in the framework of the minimal supersymmetric extension of the standard model with local B -L gauge symmetry, we investigate branching ratios and forward-backward asymmetries of rare decay B →XSl+l- in low and high q2 regions, respectively. In addition, we also study the C P asymmetries depending on new C P phases from soft breaking terms in low and high q2 regions. Assuming that the soft breaking terms of the model induce new sources for flavor-changing neutral currents and CP violations, the numerical analyses of the supersymmetric contributions to the branching ratios, forward-backward and C P asymmetries of B →XSl+l- are presented in low and high q2 regions, respectively.

  8. Natural hazard modeling and uncertainty analysis [Chapter 2

    Treesearch

    Matthew Thompson; Jord J. Warmink

    2017-01-01

    Modeling can play a critical role in assessing and mitigating risks posed by natural hazards. These modeling efforts generally aim to characterize the occurrence, intensity, and potential consequences of natural hazards. Uncertainties surrounding the modeling process can have important implications for the development, application, evaluation, and interpretation of...

  9. Coordinated scheduling of electricity and natural gas infrastructures with a transient model for natural gas flow

    NASA Astrophysics Data System (ADS)

    Liu, Cong; Shahidehpour, Mohammad; Wang, Jianhui

    2011-06-01

    This paper focuses on transient characteristics of natural gas flow in the coordinated scheduling of security-constrained electricity and natural gas infrastructures. The paper takes into account the slow transient process in the natural gas transmission systems. Considering their transient characteristics, natural gas transmission systems are modeled as a set of partial differential equations (PDEs) and algebraic equations. An implicit finite difference method is applied to approximate PDEs by difference equations. The coordinated scheduling of electricity and natural gas systems is described as a bi-level programming formulation from the independent system operator's viewpoint. The objective of the upper-level problem is to minimize the operating cost of electric power systems while the natural gas scheduling optimization problem is nested within the lower-level problem. Numerical examples are presented to verify the effectiveness of the proposed solution and to compare the solutions for steady-state and transient models of natural gas transmission systems.

  10. Coordinated scheduling of electricity and natural gas infrastructures with a transient model for natural gas flow.

    PubMed

    Liu, Cong; Shahidehpour, Mohammad; Wang, Jianhui

    2011-06-01

    This paper focuses on transient characteristics of natural gas flow in the coordinated scheduling of security-constrained electricity and natural gas infrastructures. The paper takes into account the slow transient process in the natural gas transmission systems. Considering their transient characteristics, natural gas transmission systems are modeled as a set of partial differential equations (PDEs) and algebraic equations. An implicit finite difference method is applied to approximate PDEs by difference equations. The coordinated scheduling of electricity and natural gas systems is described as a bi-level programming formulation from the independent system operator's viewpoint. The objective of the upper-level problem is to minimize the operating cost of electric power systems while the natural gas scheduling optimization problem is nested within the lower-level problem. Numerical examples are presented to verify the effectiveness of the proposed solution and to compare the solutions for steady-state and transient models of natural gas transmission systems.

  11. The Nature of Information Science: Changing Models

    ERIC Educational Resources Information Center

    Robinson, Lyn; Karamuftuoglu, Murat

    2010-01-01

    Introduction: This paper considers the nature of information science as a discipline and profession. Method: It is based on conceptual analysis of the information science literature, and consideration of philosophical perspectives, particularly those of Kuhn and Peirce. Results: It is argued that information science may be understood as a field of…

  12. Cultural mosaics and mental models of nature

    PubMed Central

    Bang, Megan; Medin, Douglas L.; Atran, Scott

    2007-01-01

    For much of their history, the relationship between anthropology and psychology has been well captured by Robert Frost's poem, “Mending Wall,” which ends with the ironic line, “good fences make good neighbors.” The congenial fence was that anthropology studied what people think and psychology studied how people think. Recent research, however, shows that content and process cannot be neatly segregated, because cultural differences in what people think affect how people think. To achieve a deeper understanding of the relation between process and content, research must integrate the methodological insights from both anthropology and psychology. We review previous research and describe new studies in the domain of folk biology which examine the cognitive consequences of different conceptualizations of nature and the place of humans within it. The focus is on cultural differences in framework theories (epistemological orientations) among Native Americans (Menominee) and European American children and adults living in close proximity in rural Wisconsin. Our results show that epistemological orientations affect memory organization, ecological reasoning, and the perceived role of humans in nature. This research also demonstrates that cultural differences in framework theories have implications for understanding intergroup conflict over natural resources and are relevant to efforts to improve science learning, especially among Native American children. PMID:17715299

  13. Cultural mosaics and mental models of nature.

    PubMed

    Bang, Megan; Medin, Douglas L; Atran, Scott

    2007-08-28

    For much of their history, the relationship between anthropology and psychology has been well captured by Robert Frost's poem, "Mending Wall," which ends with the ironic line, "good fences make good neighbors." The congenial fence was that anthropology studied what people think and psychology studied how people think. Recent research, however, shows that content and process cannot be neatly segregated, because cultural differences in what people think affect how people think. To achieve a deeper understanding of the relation between process and content, research must integrate the methodological insights from both anthropology and psychology. We review previous research and describe new studies in the domain of folk biology which examine the cognitive consequences of different conceptualizations of nature and the place of humans within it. The focus is on cultural differences in framework theories (epistemological orientations) among Native Americans (Menominee) and European American children and adults living in close proximity in rural Wisconsin. Our results show that epistemological orientations affect memory organization, ecological reasoning, and the perceived role of humans in nature. This research also demonstrates that cultural differences in framework theories have implications for understanding intergroup conflict over natural resources and are relevant to efforts to improve science learning, especially among Native American children.

  14. MODELING NATURAL ATTENUATION OF FUELS WITH BIOPLUME III

    EPA Science Inventory

    A natural attenuation model that simulates the aerobic and anaerobic biodegradation of fuel hydrocarbons was developed. The resulting model, BIOPLUME III, demonstrates the importance of biodegradation in reducing contaminant concentrations in ground water. In hypothetical simulat...

  15. World Energy Projection System Plus Model Documentation: Natural Gas Module

    EIA Publications

    2011-01-01

    This report documents the objectives, analytical approach and development of the World Energy Projection System Plus (WEPS ) Natural Gas Model. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code.

  16. Parametric Wave Transformation Models on Natural Beaches

    NASA Astrophysics Data System (ADS)

    Apotsos, A. A.; Raubenheimer, B.; Elgar, S.; Guza, R. T.

    2006-12-01

    Seven parametric models for wave height transformation across the surf zone [e.g., Thornton and Guza, 1983] are tested with observations collected between the shoreline and about 5-m water depth during 2 experiments on a barred beach near Duck, NC, and between the shoreline and about 3.5-m water depth during 2 experiments on unbarred beaches near La Jolla, CA. Offshore wave heights ranged from about 0.1 to 3.0 m. Beach profiles were surveyed approximately every other day. The models predict the observations well. Root-mean-square errors between observed and simulated wave heights are small in water depths h > 2 m (average rms errors < 10%), and increase with decreasing depth for h < 2 m (average rms errors > 20%). The lowest rms errors (i.e., the most accurate predictions) are achieved by tuning a free parameter, γ, in each model. To tune the models accurately to the data considered here, observations are required at 3 to 5 locations, and must span the surf zone. No tuned or untuned model provides the best predictions for all data records in any one experiment. The best fit γ's for each model-experiment pair are represented well with an empirical hyperbolic tangent curve based on the inverse Iribarren number. In 3 of the 4 data sets, estimating γ for each model using an average curve based on the predictions and observations from all 4 experiments typically improves model-data agreement relative to using a constant or previously determined empirical γ. The best fit γ's at the 4th experiment (conducted off La Jolla, CA) are roughly 20% smaller than the γ's for the other 3 experiments, and thus using the experiment-averaged curve increases prediction errors. Possible causes for the smaller γ's at the 4th experiment will be discussed. Funded by ONR and NSF.

  17. Scattering measurements on natural and model trees

    NASA Technical Reports Server (NTRS)

    Rogers, James C.; Lee, Sung M.

    1990-01-01

    The acoustical back scattering from a simple scale model of a tree has been experimentally measured. The model consisted of a trunk and six limbs, each with 4 branches; no foliage or twigs were included. The data from the anechoic chamber measurements were then mathematically combined to construct the effective back scattering from groups of trees. Also, initial measurements have been conducted out-of-doors on a single tree in an open field in order to characterize its acoustic scattering as a function of azimuth angle. These measurements were performed in the spring, prior to leaf development. The data support a statistical model of forest scattering; the scattered signal spectrum is highly irregular but with a remarkable general resemblance to the incident signal spectrum. Also, the scattered signal's spectra showed little dependence upon scattering angle.

  18. Partially natural two Higgs doublet models

    SciTech Connect

    Draper, Patrick; Haber, Howard E.; Ruderman, Joshua T.

    2016-06-21

    It is possible that the electroweak scale is low due to the fine-tuning of microscopic parameters, which can result from selection effects. The experimental discovery of new light fundamental scalars other than the Standard Model Higgs boson would seem to disfavor this possibility, since generically such states imply parametrically worse fine-tuning with no compelling connection to selection effects. We discuss counterexamples where the Higgs boson is light because of fine-tuning, and a second scalar doublet is light because a discrete symmetry relates its mass to the mass of the Standard Model Higgs boson. Our examples require new vectorlike fermions at the electroweak scale, and the models possess a rich electroweak vacuum structure. Furthermore, the mechanism that we discuss does not protect a small CP-odd Higgs mass in split or high-scale supersymmetry-breaking scenarios of the MSSM due to an incompatibility between the discrete symmetries and holomorphy.

  19. Understanding Surface Adhesion in Nature: A Peeling Model.

    PubMed

    Gu, Zhen; Li, Siheng; Zhang, Feilong; Wang, Shutao

    2016-07-01

    Nature often exhibits various interesting and unique adhesive surfaces. The attempt to understand the natural adhesion phenomena can continuously guide the design of artificial adhesive surfaces by proposing simplified models of surface adhesion. Among those models, a peeling model can often effectively reflect the adhesive property between two surfaces during their attachment and detachment processes. In the context, this review summarizes the recent advances about the peeling model in understanding unique adhesive properties on natural and artificial surfaces. It mainly includes four parts: a brief introduction to natural surface adhesion, the theoretical basis and progress of the peeling model, application of the peeling model, and finally, conclusions. It is believed that this review is helpful to various fields, such as surface engineering, biomedicine, microelectronics, and so on.

  20. Understanding Surface Adhesion in Nature: A Peeling Model

    PubMed Central

    Gu, Zhen; Li, Siheng; Zhang, Feilong

    2016-01-01

    Nature often exhibits various interesting and unique adhesive surfaces. The attempt to understand the natural adhesion phenomena can continuously guide the design of artificial adhesive surfaces by proposing simplified models of surface adhesion. Among those models, a peeling model can often effectively reflect the adhesive property between two surfaces during their attachment and detachment processes. In the context, this review summarizes the recent advances about the peeling model in understanding unique adhesive properties on natural and artificial surfaces. It mainly includes four parts: a brief introduction to natural surface adhesion, the theoretical basis and progress of the peeling model, application of the peeling model, and finally, conclusions. It is believed that this review is helpful to various fields, such as surface engineering, biomedicine, microelectronics, and so on. PMID:27812476

  1. Teachers' Views on the Nature of Models

    ERIC Educational Resources Information Center

    Justi, Rosaria S.; Gilbert, John K.

    2003-01-01

    A semi-structured interview was used in Brazil to enquire into the "notion of model" held by a total sample of 39 science teachers who were: employed in "fundamental" (6-14 years) and "medium" (15-17 years) schools; student science teachers currently doing their practicum; and university science teachers. Seven…

  2. Model documentation: Natural gas transmission and distribution model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1995-02-17

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of integrated Analysis and Forecasting of the Energy information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The methodology employed allows the analysis of impacts of regional capacity constraints in the interstate natural gas pipeline network and the identification of pipeline capacity expansion requirements. There is an explicit representation of core and noncore markets for natural gas transmission and distribution services, and the key components of pipeline tariffs are represented in a pricing algorithm. Natural gas pricing and flow patterns are derived by obtaining a market equilibrium across the three main elements of the natural gas market: the supply element, the demand element, and the transmission and distribution network that links them. The NGTDM consists of four modules: the Annual Flow Module, the Capacity F-expansion Module, the Pipeline Tariff Module, and the Distributor Tariff Module. A model abstract is provided in Appendix A.

  3. Partially natural two Higgs doublet models

    DOE PAGES

    Draper, Patrick; Haber, Howard E.; Ruderman, Joshua T.

    2016-06-21

    It is possible that the electroweak scale is low due to the fine-tuning of microscopic parameters, which can result from selection effects. The experimental discovery of new light fundamental scalars other than the Standard Model Higgs boson would seem to disfavor this possibility, since generically such states imply parametrically worse fine-tuning with no compelling connection to selection effects. We discuss counterexamples where the Higgs boson is light because of fine-tuning, and a second scalar doublet is light because a discrete symmetry relates its mass to the mass of the Standard Model Higgs boson. Our examples require new vectorlike fermions atmore » the electroweak scale, and the models possess a rich electroweak vacuum structure. Furthermore, the mechanism that we discuss does not protect a small CP-odd Higgs mass in split or high-scale supersymmetry-breaking scenarios of the MSSM due to an incompatibility between the discrete symmetries and holomorphy.« less

  4. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

    Chipera, S.J.; Bish, D.L.

    1997-06-01

    Zeolites occur in a variety of geologic environments and are used in numerous agricultural, commercial, and environmental applications. It is desirable to understand their stability both to predict future stability and to evaluate the geochemical conditions resulting in their formation. The use of estimated thermodynamic data for measured zeolite compositions allows thermodynamic modeling of stability relationships among zeolites in different geologic environments (diagenetic, saline and alkaline lakes, acid rock hydrothermal, basic rock, deep sea sediments). This modeling shows that the relative cation abundances in both the aqueous and solid phases, the aqueous silica activity, and temperature are important factors in determining the stable zeolite species. Siliceous zeolites (e.g., clinoptilolite, mordenite, erionite) present in saline and alkaline lakes or diagenetic deposits formed at elevated silica activities. Aluminous zeolites (e.g., natrolite, mesolite/scolecite, thomsonite) formed in basic rocks in association with reduced silica activities. Likewise, phillipsite formation is favored by reduced aqueous silica activities. The presence of erionite, chabazite, and phillipsite are indicative of environments with elevated potassium concentrations. Elevated temperature, calcic water conditions, and reduced silica activity help to enhance the laumontite and wairakite stability fields. Analcime stability increases with increased temperature and aqueous Na concentration, and/or with decreased silica activity.

  5. Naturalness and renormalization group in the standard model

    NASA Astrophysics Data System (ADS)

    Pivovarov, Grigorii B.

    2016-10-01

    I define a naturalness criterion formalizing the intuitive notion of naturalness discussed in the literature. After that, using ϕ4 as an example, I demonstrate that a theory may be natural in the MS-scheme and, at the same time, unnatural in the Gell-Mann-Low scheme. Finally, I discuss the prospects of using a version of the Gell-Mann-Low scheme in the Standard Model.

  6. Naturalness and Renormalization Group in the Standard Model

    NASA Astrophysics Data System (ADS)

    Pivovarov, Grigorii B.

    I define a naturalness criterion formalizing the intuitive notion of naturalness discussed in the literature. After that, using ϕ4 as an example, I demonstrate that a theory may be natural in the MS-scheme and, at the same time, unnatural in the Gell-Mann-Low scheme. Finally, I discuss the prospects of using a version of the Gell-Mann-Low scheme in the Standard Model.

  7. Models for naturally fractured, carbonate reservoir simulations

    SciTech Connect

    Tuncay, K.; Park, A.; Ozkan, G.; Zhan, X.; Ortoleva, P.; Hoak, T.; Sundberg, K.

    1998-12-31

    This report outlines the need for new tools for the simulation of fractured carbonate reservoirs. Several problems are identified that call for the development of new reservoir simulation physical models and numerical techniques. These include: karst and vuggy media wherein Darcy`s and traditional multi-phase flow laws do not apply; the need for predicting the preproduction state of fracturing and stress so that the later response of effective stress-dependent reservoirs can be predicted; and methods for predicting the fracturing and collapse of vuggy and karst reservoirs in response to draw-down pressure created during production. Specific research directions for addressing each problem are outlined and preliminary results are noted.

  8. Fractal Modeling and Scaling in Natural Systems - Editorial

    USDA-ARS?s Scientific Manuscript database

    The special issue of Ecological complexity journal on Fractal Modeling and Scaling in Natural Systems contains representative examples of the status and evolution of data-driven research into fractals and scaling in complex natural systems. The editorial discusses contributions to understanding rela...

  9. Using STELLA Simulation Models to Teach Natural Resource Economics

    ERIC Educational Resources Information Center

    Dissanayake, Sahan T. M.

    2016-01-01

    In this article, the author discusses how graphical simulation models created using STELLA software can be used to present natural resource systems in an intuitive way in undergraduate natural resource economics classes based on his experiences at a leading research university, a state university, and a leading liberal arts college in the United…

  10. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  11. A Working Model of Natural Selection Illustrated by Table Tennis

    ERIC Educational Resources Information Center

    Dinc, Muhittin; Kilic, Selda; Aladag, Caner

    2013-01-01

    Natural selection is one of the most important topics in biology and it helps to clarify the variety and complexity of organisms. However, students in almost every stage of education find it difficult to understand the mechanism of natural selection and they can develop misconceptions about it. This article provides an active model of natural…

  12. Using STELLA Simulation Models to Teach Natural Resource Economics

    ERIC Educational Resources Information Center

    Dissanayake, Sahan T. M.

    2016-01-01

    In this article, the author discusses how graphical simulation models created using STELLA software can be used to present natural resource systems in an intuitive way in undergraduate natural resource economics classes based on his experiences at a leading research university, a state university, and a leading liberal arts college in the United…

  13. A Goal-Oriented Model of Natural Language Interaction.

    ERIC Educational Resources Information Center

    Moore, James A.; And Others

    This report summarizes a research program in modeling human communication ability. The methodology involved selecting a single, naturally occurring dialogue, instructing a human observer to extract certain aspects relative to its comprehension, and then using these aspects to guide the construction and verification of the model. The model assumes…

  14. [Ecotourism exploitation model in Bita Lake Natural Reserve of Yunnan].

    PubMed

    Yang, G; Wang, Y; Zhong, L

    2000-12-01

    Bita lake provincial natural reserve is located in Shangri-La region of North-western Yunnan, and was set as a demonstrating area for ecotourism exploitation in 1998. After a year's exploitation construction and half a year's operation as a branch of the 99' Kunming International Horticulture Exposition to accept tourists, it was proved that the ecotourism demonstrating area attained four integrated functions of ecotourism, i.e., tourism, protection, poverty clearing and environment education. Five exploitation and management models including function zoned exploitation model, featured tourism communication model signs system designing model, local Tibetan family reception model and environmental monitoring model, were also successful, which were demonstrated and spreaded to the whole province. Bita lake provincial natural reserve could be a good sample for the ecotourism exploitation natural reserves of the whole country.

  15. Sterile neutrino portal to Dark Matter I: the U(1) B- L case

    NASA Astrophysics Data System (ADS)

    Escudero, Miguel; Rius, Nuria; Sanz, Verónica

    2017-02-01

    In this paper we explore the possibility that the sterile neutrino and Dark Matter sectors in the Universe have a common origin. We study the consequences of this assumption in the simple case of coupling the dark sector to the Standard Model via a global U(1) B-L , broken down spontaneously by a dark scalar. This dark scalar provides masses to the dark fermions and communicates with the Higgs via a Higgs portal coupling. We find an interesting interplay between Dark Matter annihilation to dark scalars — the CP-even that mixes with the Higgs and the CP-odd which becomes a Goldstone boson, the Majoron — and heavy neutrinos, as well as collider probes via the coupling to the Higgs. Moreover, Dark Matter annihilation into sterile neutrinos and its subsequent decay to gauge bosons and quarks, charged leptons or neutrinos lead to indirect detection signatures which are close to current bounds on the gamma ray flux from the galactic center and dwarf galaxies.

  16. Analysis and modeling of naturalness in handwritten characters.

    PubMed

    Dolinský, Ján; Takagi, Hideyuki

    2009-10-01

    In this paper, we define the naturalness of handwritten characters as being the difference between the strokes of the handwritten characters and the archetypal fonts on which they are based. With this definition, we mathematically analyze the relationship between the font and its naturalness using canonical correlation analysis (CCA), multiple linear regression analysis, feedforward neural networks (FFNNs) with sliding windows, and recurrent neural networks (RNNs). This analysis reveals that certain properties of font character strokes do not have a linear relationship with their naturalness. In turn, this suggests that nonlinear techniques should be used to model the naturalness, and in our investigations, we find that an RNN with a recurrent output layer performs the best among four linear and nonlinear models. These results indicate that it is possible to model naturalness, defined in our study as the difference between handwritten and archetypal font characters but more generally as the difference between the behavior of a natural system and a corresponding basic system, and that naturalness learning is a promising approach for generating handwritten characters.

  17. Molecular cloning of the Escherichia coli B L-fucose-D-arabinose gene cluster.

    PubMed Central

    Elsinghorst, E A; Mortlock, R P

    1994-01-01

    To metabolize the uncommon pentose D-arabinose, enteric bacteria often recruit the enzymes of the L-fucose pathway by a regulatory mutation. However, Escherichia coli B can grow on D-arabinose without the requirement of a mutation, using some of the L-fucose enzymes and a D-ribulokinase that is distinct from the L-fuculokinase of the L-fucose pathway. To study this naturally occurring D-arabinose pathway, we cloned and partially characterized the E. coli B L-fucose-D-arabinose gene cluster and compared it with the L-fucose gene cluster of E. coli K-12. The order of the fucA, -P, -I, and -K genes was the same in the two E. coli strains. However, the E. coli B gene cluster contained a 5.2-kb segment located between the fucA and fucP genes that was not present in E. coli K-12. This segment carried the darK gene, which encodes the D-ribulokinase needed for growth on D-arabinose by E. coli B. The darK gene was not homologous with any of the L-fucose genes or with chromosomal DNA from other D-arabinose-utilizing bacteria. D-Ribulokinase and L-fuculokinase were purified to apparent homogeneity and partially characterized. The molecular weights, substrate specificities, and kinetic parameters of these two enzymes were very dissimilar, which together with DNA hybridization analysis, suggested that these enzymes are not related. D-Arabinose metabolism by E. coli B appears to be the result of acquisitive evolution, but the source of the darK gene has not been determined. Images PMID:7961494

  18. Modeling natural gas market volatility using GARCH with different distributions

    NASA Astrophysics Data System (ADS)

    Lv, Xiaodong; Shan, Xian

    2013-11-01

    In this paper, we model natural gas market volatility using GARCH-class models with long memory and fat-tail distributions. First, we forecast price volatilities of spot and futures prices. Our evidence shows that none of the models can consistently outperform others across different criteria of loss functions. We can obtain greater forecasting accuracy by taking the stylized fact of fat-tail distributions into account. Second, we forecast volatility of basis defined as the price differential between spot and futures. Our evidence shows that nonlinear GARCH-class models with asymmetric effects have the greatest forecasting accuracy. Finally, we investigate the source of forecasting loss of models. Our findings based on a detrending moving average indicate that GARCH models cannot capture multifractality in natural gas markets. This may be the plausible explanation for the source of model forecasting losses.

  19. The Natural Science Environmental Education Teacher Training Model.

    ERIC Educational Resources Information Center

    Banathy, Bela H.; And Others

    Included are two sections contributing to understanding of the model: (1) Orientation; and (2) Content Specifications. The model is intended to provide the user with a frame of reference within which to formulate and plan environmental education and training products which: (1) develop grade K-9 natural science teachers' understanding of…

  20. Model documentation Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1996-02-26

    The Natural Gas Transmission and Distribution Model (NGTDM) of the National Energy Modeling System is developed and maintained by the Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting. This report documents the archived version of the NGTDM that was used to produce the natural gas forecasts presented in the Annual Energy Outlook 1996, (DOE/EIA-0383(96)). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic approach, and provides detail on the methodology employed. Previously this report represented Volume I of a two-volume set. Volume II reported on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.

  1. Self-organization, the cascade model, and natural hazards

    PubMed Central

    Turcotte, Donald L.; Malamud, Bruce D.; Guzzetti, Fausto; Reichenbach, Paola

    2002-01-01

    We consider the frequency-size statistics of two natural hazards, forest fires and landslides. Both appear to satisfy power-law (fractal) distributions to a good approximation under a wide variety of conditions. Two simple cellular-automata models have been proposed as analogs for this observed behavior, the forest fire model for forest fires and the sand pile model for landslides. The behavior of these models can be understood in terms of a self-similar inverse cascade. For the forest fire model the cascade consists of the coalescence of clusters of trees; for the sand pile model the cascade consists of the coalescence of metastable regions. PMID:11875206

  2. Can Nature Protection be Unsustainable? Models Behind Nature Protection in New Zealands National Parks

    NASA Astrophysics Data System (ADS)

    Hauhs, Michael; Bogner, Christina

    2013-04-01

    Nature protection can be justified by intrinsic values of life. Western culture sees nature as an autonomous system. Thus, nature protection is often synonymous with refraining from human interference as much as possible. This, however, can pose at least technical problems. Indeed, historical human impacts such as introduced species are often irreversible. In such cases refraining from human interference to protect threatened species is not an adequate management response. Nature protection in New Zealand is a prominent example. Many introduced species make a non-interventionist attitude infeasible to protect endemic species such as kiwis. Actually, active human interference is necessary to attain this goal. Therefore, one may consider nature protection as another form of land use. As any other form of land use, it needs standards of proper management (i.e. explicit goals, assessment, intervention etc.). In other words, it has to be shown to be sustainable. However, sustainability may rigorously be defined as an attribute of past land use only. Instantaneous positive indicators of sustainability may be elusive. At best it can be decided by observation whether or not a land use has been (not) sustainable until now. Stakeholders of nature protection have often different (implicit) concepts or models of nature in mind. This can lead to conflicts when it comes to management decisions. For example, the methods by which conservationists in New Zealand seek to re-establish historical species assemblages (e.g. aerial drop of poison into national parks) have come under criticism of animal rights groups as non-humane. We propose to use abstract modelling language to classify these concepts of nature protection and related issues. We show that from modelling perspective these conflicts pose a basic science problem rather than an applied science problem. This makes the delegation into existing disciplines so hard. We discuss possible implications for nature protection

  3. Upper Modeling: organizing knowledge for natural language processing

    DTIC Science & Technology

    1990-01-01

    Natural Language Generation in Artificial Intelligence and Computational Linguistics. Kluwer Academic Publishers, 1990. [ Steiner et al., 1987] Erich H... Steiner , 1990] Erich H. Steiner . A model off goal- directed-action as a structuring principle for the con- text of situation in systemic linguistics...aL, 1987]; the Semantic Relations of ~UROTa^-D: [ Steiner et al., 1987]; JANUS: [Weischedel, 1989]. Space naturally precludes detailed comparisons

  4. Statistical Modeling of Natural Backgrounds in Hyperspectral LWIR Data

    DTIC Science & Technology

    2016-09-06

    Statistical Modeling of Natural Backgrounds in Hyperspectral LWIR Data Eric Truslowa, Dimitris Manolakisa, Thomas Cooleyb, and Joseph Meolac aMIT...87117 cSensors Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433 Hyperspectral sensors operating in the long wave infrared (LWIR...investigated. In this paper, we investigate modeling hyperspectral LWIR data using a statistical mixture model for the emissivity and surface

  5. OysterFutures: Integrating Stakeholder Objectives with Natural System Models to Promote Sustainable Natural Resource Policy

    NASA Astrophysics Data System (ADS)

    North, E. W.; Blair, J.; Cornwell, J. C.; Freitag, A. E.; Gawde, R. K.; Hartley, T. W.; Hood, R. R.; Jones, R. M.; Miller, T. J.; Thomas, J. E.; Wainger, L. A.; Wilberg, M. J.

    2016-02-01

    Achieving effective natural resource management is challenged by multiple and often competing objectives, a restricted set of policy options, and uncertainty in the performance of those options. Yet, managers need policies that allow continued use of natural resources while ensuring access for future generations and maintenance of ecosystem services. Formal approaches are needed that will assist managers and stakeholders in choosing policy options that have a high likelihood of achieving social, ecological, and economic goals. The goal of this project, OysterFutures, is to address this need by improving the use of predictive models to support sustainable natural resource policy and management. A stakeholder-centered process will be used to build an integrated model that combines estuarine physics, oyster life history, and the ecosystem services that oysters provide (e.g., harvest, water quality) to forecast outcomes under alternative management strategies. Through a series of facilitated meetings, stakeholders will participate in a science-based collaborative process which will allow them to project how well policies are expected to meet their objectives using the integrated model. This iterative process will ensure that the model will incorporate the complex human uses of the ecosystem as well as focus on the outcomes most important to the stakeholders. In addition, a study of the socioeconomic drivers of stakeholder involvement, information flow, use and influence, and policy formation will be undertaken to improve the process, enhance implementation success of recommended policies, and provide new ideas for integrating natural and social sciences, and scientists, in sustainable resource management. In this presentation, the strategy for integrating natural system models, stakeholder views, and sociological studies as well as methods for selecting stakeholders and facilitating stakeholder meetings will be described and discussed.

  6. Approaches to modelling uranium (VI) adsorption on natural mineral assemblages

    USGS Publications Warehouse

    Waite, T.D.; Davis, J.A.; Fenton, B.R.; Payne, T.E.

    2000-01-01

    Component additivity (CA) and generalised composite (GC) approaches to deriving a suitable surface complexation model for description of U(VI) adsorption to natural mineral assemblages are pursued in this paper with good success. A single, ferrihydrite-like component is found to reasonably describe uranyl uptake to a number of kaolinitic iron-rich natural substrates at pH > 4 in the CA approach with previously published information on nature of surface complexes, acid-base properties of surface sites and electrostatic effects used in the model. The GC approach, in which little pre-knowledge about generic surface sites is assumed, gives even better fits and would appear to be a method of particular strength for application in areas such as performance assessment provided the model is developed in a careful, stepwise manner with simplicity and goodness of fit as the major criteria for acceptance.

  7. a model based on crowsourcing for detecting natural hazards

    NASA Astrophysics Data System (ADS)

    Duan, J.; Ma, C.; Zhang, J.; Liu, S.; Liu, J.

    2015-12-01

    Remote Sensing Technology provides a new method for the detecting,early warning,mitigation and relief of natural hazards. Given the suddenness and the unpredictability of the location of natural hazards as well as the actual demands for hazards work, this article proposes an evaluation model for remote sensing detecting of natural hazards based on crowdsourcing. Firstly, using crowdsourcing model and with the help of the Internet and the power of hundreds of millions of Internet users, this evaluation model provides visual interpretation of high-resolution remote sensing images of hazards area and collects massive valuable disaster data; secondly, this evaluation model adopts the strategy of dynamic voting consistency to evaluate the disaster data provided by the crowdsourcing workers; thirdly, this evaluation model pre-estimates the disaster severity with the disaster pre-evaluation model based on regional buffers; lastly, the evaluation model actuates the corresponding expert system work according to the forecast results. The idea of this model breaks the boundaries between geographic information professionals and the public, makes the public participation and the citizen science eventually be realized, and improves the accuracy and timeliness of hazards assessment results.

  8. Numerical Modeling of Fracture Propagation in Naturally Fractured Formations

    NASA Astrophysics Data System (ADS)

    Wang, W.; Prodanovic, M.; Olson, J. E.; Schultz, R.

    2015-12-01

    Hydraulic fracturing consists of injecting fluid at high pressure and high flowrate to the wellbore for the purpose of enhancing production by generating a complex fracture network. Both tensile failure and shear failure occur during the hydraulic fracturing treatment. The shear event can be caused by slip on existing weak planes such as faults or natural fractures. From core observation, partially cemented and fully cemented opening mode natural fractures, often with considerable thickness are widely present. Hydraulic fractures can propagate either within the natural fracture (tensile failure) or along the interface between the natural fracture and the rock matrix (tensile/shear failure), depending on the relative strength of cement and rock matrix materials, the bonding strength of interface, as well as the presence of any heterogeneities. In this study, we evaluate the fracture propagation both experimentally and numerically. We embed one or multiple inclusions of different mechanical properties within synthetic hydrostone samples in order to mimic cemented natural fractures and rock. A semi-circular bending test is performed for each set of properties. A finite element model built with ABAQUS is used to mimic the semi-circular bending test and study the fracture propagation path, as well as the matrix-inclusion bonding interface status. Mechanical properties required for the numerical model are measured experimentally. The results indicate that the match between experiment and modeling fracture path are extremely sensitive to the chosen interface (bonding) model and related parameters. The semi-circular bending test is dry and easily conducted, providing a good platform for validating numerical approaches. A validated numerical model will enable us to add pressurized fluid within the crack and simulate hydraulic fracture-natural fracture interaction in the reservoir conditions, ultimately providing insights into the extent of the fracture network.

  9. A novel trauma model: naturally occurring canine trauma.

    PubMed

    Hall, Kelly E; Sharp, Claire R; Adams, Cynthia R; Beilman, Gregory

    2014-01-01

    In human trauma patients, most deaths result from hemorrhage and brain injury, whereas late deaths, although rare, are the result of multiple organ failure and sepsis. A variety of experimental animal models have been developed to investigate the pathophysiology of traumatic injury and evaluate novel interventions. Similar to other experimental models, these trauma models cannot recapitulate conditions of naturally occurring trauma, and therefore therapeutic interventions based on these models are often ineffective. Pet dogs with naturally occurring traumatic injury represent a promising translational model for human trauma that could be used to assess novel therapies. The purpose of this article was to review the naturally occurring canine trauma literature to highlight the similarities between canine and human trauma. The American College of Veterinary Emergency and Critical Care Veterinary Committee on Trauma has initiated the establishment of a national network of veterinary trauma centers to enhance uniform delivery of care to canine trauma patients. In addition, the Spontaneous Trauma in Animals Team, a multidisciplinary, multicenter group of researchers has created a clinical research infrastructure for carrying out large-scale clinical trials in canine trauma patients. Moving forward, these national resources can be utilized to facilitate multicenter prospective studies of canine trauma to evaluate therapies and interventions that have shown promise in experimental animal models, thus closing the critical gap in the translation of knowledge from experimental models to humans and increasing the likelihood of success in phases 1 and 2 human clinical trials.

  10. Fishing for Nature's Hits: Establishment of the Zebrafish as a Model for Screening Antidiabetic Natural Products

    PubMed Central

    Tabassum, Nadia; Tai, Hongmei; Jung, Da-Woon; Williams, Darren R.

    2015-01-01

    Diabetes mellitus affects millions of people worldwide and significantly impacts their quality of life. Moreover, life threatening diseases, such as myocardial infarction, blindness, and renal disorders, increase the morbidity rate associated with diabetes. Various natural products from medicinal plants have shown potential as antidiabetes agents in cell-based screening systems. However, many of these potential “hits” fail in mammalian tests, due to issues such as poor pharmacokinetics and/or toxic side effects. To address this problem, the zebrafish (Danio rerio) model has been developed as a “bridge” to provide an experimentally convenient animal-based screening system to identify drug candidates that are active in vivo. In this review, we discuss the application of zebrafish to drug screening technologies for diabetes research. Specifically, the discovery of natural product-based antidiabetes compounds using zebrafish will be described. For example, it has recently been demonstrated that antidiabetic natural compounds can be identified in zebrafish using activity guided fractionation of crude plant extracts. Moreover, the development of fluorescent-tagged glucose bioprobes has allowed the screening of natural product-based modulators of glucose homeostasis in zebrafish. We hope that the discussion of these advances will illustrate the value and simplicity of establishing zebrafish-based assays for antidiabetic compounds in natural products-based laboratories. PMID:26681965

  11. Model documentation: Natural Gas Transmission and Distribution Model of the National Energy Modeling System; Volume 1

    SciTech Connect

    1994-02-24

    The Natural Gas Transmission and Distribution Model (NGTDM) is a component of the National Energy Modeling System (NEMS) used to represent the domestic natural gas transmission and distribution system. NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the Energy Information Administration (EIA) and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. This report documents the archived version of NGTDM that was used to produce the natural gas forecasts used in support of the Annual Energy Outlook 1994, DOE/EIA-0383(94). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. It is intended to fulfill the legal obligation of the EIA to provide adequate documentation in support of its models (Public Law 94-385, Section 57.b.2). This report represents Volume 1 of a two-volume set. (Volume 2 will report on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.) Subsequent chapters of this report provide: (1) an overview of the NGTDM (Chapter 2); (2) a description of the interface between the National Energy Modeling System (NEMS) and the NGTDM (Chapter 3); (3) an overview of the solution methodology of the NGTDM (Chapter 4); (4) the solution methodology for the Annual Flow Module (Chapter 5); (5) the solution methodology for the Distributor Tariff Module (Chapter 6); (6) the solution methodology for the Capacity Expansion Module (Chapter 7); (7) the solution methodology for the Pipeline Tariff Module (Chapter 8); and (8) a description of model assumptions, inputs, and outputs (Chapter 9).

  12. A Simple Model for Human and Nature Interaction

    NASA Astrophysics Data System (ADS)

    Motesharrei, S.; Rivas, J.; Kalnay, E.

    2012-12-01

    There are widespread concerns that current trends in population and resource-use are unsustainable, but the possibilities of an overshoot and collapse remain unclear and controversial. Collapses of civilizations have occurred many times in the past 5000 years, often followed by centuries of economic, intellectual, and population decline. Many different natural and social phenomena have been invoked to explain specific collapses, but a general explanation remains elusive. Two important features seem to appear across societies that have collapsed: Ecological Strain and Economic Stratification. Our new model (Human And Nature DYnamics, HANDY) has just four equations that describe the evolution of Elites, Commoners, Nature, and Wealth. Mechanisms leading to collapse are discussed and the measure "Carrying Capacity" is developed and defined. The model shows that societal collapse can happen due to either one of two independent factors: (1) over-consumption of natural resources, and/or (2) deep inequity between Elites and Commoners. The model also portrays two distinct types of collapse: (i) collapse followed by recovery of nature, and (ii) full collapse. The model suggests that the estimation of Carrying Capacity is a practical means for early detection of a collapse. Collapse can be avoided, and population can reach a sustainable equilibrium, if the rate of depletion of nature is reduced to a sustainable level, and if resources are distributed in a reasonably equitable fashion.; A type-ii (full) collapse is shown in this figure. With high inequality and high depletion, societies are doomed to collapse. Wealth starts to decrease when population rises above the carrying capacity. The large gap between carrying capacity and its maximum is a result of depletion factor being much larger than the sustainable limit. ; It is possible to overshoot, oscillate, and eventually converge to an equilibrium, even in an inequitable society. However, it requires policies that control

  13. [Ethology of the family (natural models of family physiology)].

    PubMed

    Cyrulnik, B; Leroy, R

    1977-06-01

    The Ethology of the Family allows in a first step to collect naturals models of family organisations. It results an extreme diversity where all family forms exist: maternal, paternal, biparental, solitary. However we can find in this notion of socialitary peogramme where a certain mode of social operation is inscribed in the genetic code.

  14. Building a Model Explaining the Social Nature of Online Learning

    ERIC Educational Resources Information Center

    Tsai, I-Chun; Kim, Bosung; Liu, Pei-Ju; Goggins, Sean P.; Kumalasari, Christiana; Laffey, James M.

    2008-01-01

    Based on a framework emphasizing the social nature of learning, this research examines a model of how social constructs affect satisfaction within online learning using path analysis for students in higher education. The social constructs evaluated in this study include sense of community (SOC), social ability (SA), perceived ease of use (PEU) and…

  15. Building a Model Explaining the Social Nature of Online Learning

    ERIC Educational Resources Information Center

    Tsai, I-Chun; Kim, Bosung; Liu, Pei-Ju; Goggins, Sean P.; Kumalasari, Christiana; Laffey, James M.

    2008-01-01

    Based on a framework emphasizing the social nature of learning, this research examines a model of how social constructs affect satisfaction within online learning using path analysis for students in higher education. The social constructs evaluated in this study include sense of community (SOC), social ability (SA), perceived ease of use (PEU) and…

  16. Naturalness, privacy, and restorative experiences in wilderness: An integrative model

    Treesearch

    William E. Hammitt

    2012-01-01

    It is suggested that the wilderness experience is a restorative experience that results from the interconnectivity between naturalness/ remoteness and privacy/unconfinement and the four components essential for an environment to be restorative. A model-framework is offered to illustrate the linkages among the environmental, social, and restoration components of...

  17. Nature of Science and Models: Comparing Portuguese Prospective Teachers' Views

    ERIC Educational Resources Information Center

    Torres, Joana; Vasconcelos, Clara

    2015-01-01

    Despite the relevance of nature of science and scientific models in science education, studies reveal that students do not possess adequate views regarding these topics. Bearing in mind that both teachers' views and knowledge strongly influence students' educational experiences, the main scope of this study was to evaluate Portuguese prospective…

  18. Data Modeling & the Infrastructural Nature of Conceptual Tools

    ERIC Educational Resources Information Center

    Lesh, Richard; Caylor, Elizabeth; Gupta, Shweta

    2007-01-01

    The goal of this paper is to demonstrate the infrastructural nature of many modern conceptual technologies. The focus of this paper is on conceptual tools associated with elementary types of data modeling. We intend to show a variety of ways in which these conceptual tools not only express thinking, but also mold and shape thinking. And those ways…

  19. Nature of Science and Models: Comparing Portuguese Prospective Teachers' Views

    ERIC Educational Resources Information Center

    Torres, Joana; Vasconcelos, Clara

    2015-01-01

    Despite the relevance of nature of science and scientific models in science education, studies reveal that students do not possess adequate views regarding these topics. Bearing in mind that both teachers' views and knowledge strongly influence students' educational experiences, the main scope of this study was to evaluate Portuguese prospective…

  20. Rill erosion in natural and disturbed forests: 2. Modeling approaches

    Treesearch

    J. W. Wagenbrenner; P. R. Robichaud; W. J. Elliot

    2010-01-01

    As forest management scenarios become more complex, the ability to more accurately predict erosion from those scenarios becomes more important. In this second part of a two-part study we report model parameters based on 66 simulated runoff experiments in two disturbed forests in the northwestern U.S. The 5 disturbance classes were natural, 10-month old and 2-week old...

  1. PREDETERMINATION OF NATURAL ILLUMINATION BY THE MODEL TESTING METHOD.

    ERIC Educational Resources Information Center

    PENA, WILLIAM A.

    NEW EDUCATIONAL SPECIFICATIONS HAVE CAUSED ARCHITECTS TO USE NEW FORMS WITH THEIR RESULTING NATURAL LIGHTING PROBLEMS. THE PROBLEM CAN BE ENGINEERED WITH THE USE OF MODELS. PREDICTION OF LIGHTING PERFORMANCE IN A BUILDING CAN BE MADE EARLY IN PLANNING. THIS METHOD PROVIDES FOR THE TESTING OF A VARIETY OF TRIAL SCHEMES ECONOMICALLY AND RAPIDLY.…

  2. Modelling of natural and bypass transition in aerodynamics

    NASA Astrophysics Data System (ADS)

    Fürst, Jiří; Straka, Petr; Příhoda, Jaromír

    2014-03-01

    Most of transition models are proposed for modelling of the bypass transition common in the internal aerodynamics especially in turbomachinery where free stream turbulence is the dominant parameter affecting the transition onset. Free-stream turbulence level in the external aerodynamics is usually noticeably lower and so the natural transition often occurs in flows around airfoils. The transition model with the algebraic equation for the intermittency coefficient proposed originally by Straka and Příhoda [3] for the bypass transition was modified for modelling of the transition at low free-stream turbulence. The modification is carried out using experimental data of Schubauer and Skramstad [18]. Further, the three-equation k-kL-ω model proposed by Walters and Cokljat [10] was used for the modelling of the transition at low free-stream turbulence. Both models were tested by means of the incompressible flow around airfoils at moderate and very low free-stream turbulence.

  3. Measuring and Modeling Naturally Occurring Radioactive Material: Interpreting the Relationship Between the Natural Radionuclides Present

    SciTech Connect

    Lombardo, A.J.; Mucha, A.F.

    2008-07-01

    The regulatory release of sites and facilities (property) for restricted or unrestricted use has evolved beyond prescribed levels to model-derived dose and risk based limits. Dose models for deriving corresponding soil and structure radionuclide concentration guidelines are necessarily simplified representations of complex processes. A conceptual site model is often developed to present a reasonable and somewhat conservative representation of the physical and chemical properties of the impacted material. Dose modeling software is then used to estimate resulting dose and/or radionuclide specific acceptance criteria (activity concentrations). When the source term includes any or all of the uranium, thorium or actinium natural decay series radionuclides the interpretation of the relationship between the individual radionuclides of the series is critical to a technically correct and complete assessment of risk and/or derivation of radionuclide specific acceptance criteria. Unlike man-made radionuclides, modeling and measuring naturally occurring radioactive material (NORM) and technologically enhanced NORM (TENORM) source terms involves the interpretation of the relationship between the radionuclide present, e.g., secular equilibrium, enrichment, depletion or transient equilibrium. Isotopes of uranium, radium, and thorium occur in all three natural decay series. Each of the three series also produces a radon gas isotope as one of its progeny. In nature, the radionuclides in the three natural decay series are in a state that is approaching or has achieved secular equilibrium, in which the activities of all radionuclides within each series are nearly equal. However, ores containing the three natural decay series may begin in approximate secular equilibrium, but after processing, equilibrium may be broken and certain elements (and the radioactive isotopes of that element) may be concentrated or removed. Where the original ore may have contained one long chain of natural

  4. The Effects of B/L-Dependent Heating on the Formation and Evolution of a Multi-Threaded Prominence

    NASA Technical Reports Server (NTRS)

    Karpen, Judith T.; Luna, M.; DeVore, C. R.

    2012-01-01

    We have developed a comprehensive, multi-threaded, three-dimensional model of the plasma dynamics and energetics of a prominence and its overlying arcade (Luna et al. 2012). In this model, the basic magnetic structure is that of two interacting sheared arcades, while the cool condensations composing the prominence are formed by the well-studied thermal nonequilibrium mechanism. In a given filament-channel flux tube, the mass is evaporated from the chromosphere by heating localized near the footpoints, and condenses in the form of transient blobs or a persistent thread. Our previous studies of thermal nonequilibrium used steady or impulsive heating functions with no dependence on local physical. However, parametric active-region models with steady heating proportional to B/L, where B is the flux-tube magnetic field strength at each footpoint and L is the flux-tube length, yield the best agreement with observations (e.g., Schrijver et al. 2008). We have determined the effects of this active-region heating function on our model for the formation and evolution of prominence mass. We have also expanded the range of our computational domain to include more ofthe overlying arcade (the so-called "cavity") than in Luna et al. (2012), and have increased the number of selected flux tubes from 125 to 533. We will illustrate the time-dependent plasma behavior produced by the B/L heating function with synthetic images in several ALA passbands, and compare the resulting prominence properties with those predicted by our model with steady heating.

  5. Spatially variant mixture model for natural image segmentation

    NASA Astrophysics Data System (ADS)

    Hu, Can; Fan, Wentao; Du, Ji-Xiang; Xie, Nan

    2017-07-01

    We tackle the problem of natural image segmentation by proposing a statistical approach that is based on spatially variant finite mixture models with generalized means. The contributions can be summarized as follows: first, the proposed spatially variant mixture model exploits beta-Liouville as basic distributions for describing the underlying data structure, which demonstrated better segmentation performance than commonly used distributions, such as Gaussian; second, the mixing proportions (i.e., the probabilities of class labels) in our model are modeled via the Dirichlet compound multinomial probability density, and the spatial smoothness is imposed by adopting the function of generalized mean over the mixture model as well as mixing proportions; and finally, a variational Bayes learning approach is developed to estimate model parameters and model complexity simultaneously with closed-form solutions. The robustness, accuracy, and effectiveness of the proposed model in image segmentation are demonstrated through experiments on both natural images and synthetic images degraded by noise compared with other state-of-the-art image segmentation methods.

  6. Numerical Modeling of Natural and Enhanced Denitrification Processes in Aquifers

    NASA Astrophysics Data System (ADS)

    Kinzelbach, Wolfgang; SchäFer, Wolfgang; Herzer, JöRg

    1991-06-01

    Nitrate modeling in the groundwater environment must incorporate microbial denitrification as the major process of nitrate elimination. A multispecies transport model is presented which describes the interaction of oxygen, nitrate, organic carbon, and bacteria. Three phases (mobile pore water, biophase, and aquifer material) are taken into account. The model is applied to a natural aquifer situation as well as to an in situ remediation case where nitrate is employed as an oxidant. In the natural aquifer it is shown that the release of organic carbon from the matrix is the controlling factor for denitrification. In the remediation case, on the other hand, the data suggest that diffusion limitation of the nutrient supply to the biophase controls bacterial growth.

  7. Genetic variants associated with neurodegenerative Alzheimer disease in natural models.

    PubMed

    Salazar, Claudia; Valdivia, Gonzalo; Ardiles, Álvaro O; Ewer, John; Palacios, Adrián G

    2016-02-26

    The use of transgenic models for the study of neurodegenerative diseases has made valuable contributions to the field. However, some important limitations, including protein overexpression and general systemic compensation for the missing genes, has caused researchers to seek natural models that show the main biomarkers of neurodegenerative diseases during aging. Here we review some of these models-most of them rodents, focusing especially on the genetic variations in biomarkers for Alzheimer diseases, in order to explain their relationships with variants associated with the occurrence of the disease in humans.

  8. Geoelectromagnetic Exploration For Natural Resources: Models, Case Studies And Challenges

    NASA Astrophysics Data System (ADS)

    Meju, Maxwell A.

    This paper presents a tutorial review of electrical and electromagnetic(herein collectively called geoelectromagnetic) methods as applied in the search for natural resources. First, the paper discusses the technical problems and advances in geoelectromagnetic methods in the last decade. A scheme for integrating electrical and electromagnetic depth sounding data is suggested.Then, for natural resources exploration, it focuses on three themes: (1) understandinggeological models of resource targets, their physical properties, and the development of conceptual geoelectromagnetic exploration models, (2) overview of geoelectromagnetic case studies in resourceexploration, and (3) outstanding challenges in exploration. For brevity, model development is restricted to groundwater, geothermal and hydrocarbon resources, metallic ore-bodies (exemplified byvolcanogenic massive sulphides, porphyry coppers, and epithermal and Archaean greenstone belt gold deposits) and diamonds. In the treatment of resource exploration in this paper, the unifying themeis that geochemical processes of weathering and hydrothermal alteration form clayey products that may render natural resource targets directly or indirectly detectable by their resistivity characteristics.Since hydrated clays are an important feature of most resource types and are major causes of low resistivity anomalies in geoelectromagnetic exploration, they may be taken as providing detectable marker horizons or pathfinders and a basis for developing a consistent investigative approachfor natural resources. However, it is recognised that no single resource model or standard approach may be universally applicable. Natural resource systems are inherently 3D and require large numbers of depth soundings at high station densities to image adequately. Thus, developing methodsof increasing the productivity of data acquisition, the development of better 3D software tools and lowering costs are seen as the major challenges facing the use

  9. Developing natural resource models using the object modeling system: feasibility and challenges

    NASA Astrophysics Data System (ADS)

    Ahuja, L. R.; Ascough, J. C., II; David, O.

    2005-08-01

    Current challenges in natural resource management have created demand for integrated, flexible, and easily parameterized hydrologic models. Most of these monolithic models are not modular, thus modifications (e.g., changes in process representation) require considerable time, effort, and expense. In this paper, the feasibility and challenges of using the Object Modeling System (OMS) for natural resource model development will be explored. The OMS is a Java-based modeling framework that facilitates simulation model development, evaluation, and deployment. In general, the OMS consists of a library of science, control, and database modules and a means to assemble the selected modules into an application-specific modeling package. The framework is supported by data dictionary, data retrieval, GIS, graphical visualization, and statistical analysis utility modules. Specific features of the OMS that will be discussed include: 1) how to reduce duplication of effort in natural resource modeling; 2) how to make natural resource models easier to build, apply, and evaluate; 3) how to facilitate long-term maintainability of existing and new natural resource models; and 4) how to improve the quality of natural resource model code and ensure credibility of model implementations. Examples of integrating a simple water balance model and a large monolithic model into the OMS will be presented.

  10. Zebrafish: predictive model for targeted cancer therapeutics from nature.

    PubMed

    Zulkhernain, Nursafwana Syazwani; Teo, Soo Hwang; Patel, Vyomesh; Tan, Pei Jean

    2014-01-01

    Targeted therapy, the treatment of cancer based on an underlying genetic alteration, is rapidly gaining favor as the preferred therapeutic approach. To date, although natural products represent a rich resource of bio-diverse drug candidates, only a few have been identified to be effective as targeted cancer therapies largely due to the incompatibilities to current high-throughput screening methods. In this article, we review the utility of a zebrafish developmental screen for bioactive natural product-based compounds that target signaling pathways that are intimately shared with those in humans. Any bioactive compound perturbing signaling pathways identified from phenotypic developmental defects in zebrafish embryos provide an opportunity for developing targeted therapies for human cancers. This model provides a promising tool in the search for targeted cancer therapeutics from natural products.

  11. Diagnosing Students' Understanding of the Nature of Models

    NASA Astrophysics Data System (ADS)

    Gogolin, Sarah; Krüger, Dirk

    2017-10-01

    Students' understanding of models in science has been subject to a number of investigations. The instruments the researchers used are suitable for educational research but, due to their complexity, cannot be employed directly by teachers. This article presents forced choice (FC) tasks, which, assembled as a diagnostic instrument, are supposed to measure students' understanding of the nature of models efficiently, while being sensitive enough to detect differences between individuals. In order to evaluate if the diagnostic instrument is suitable for its intended use, we propose an approach that complies with the demand to integrate students' responses to the tasks into the validation process. Evidence for validity was gathered based on relations to other variables and on students' response processes. Students' understanding of the nature of models was assessed using three methods: FC tasks, open-ended tasks and interviews ( N = 448). Furthermore, concurrent think-aloud protocols ( N = 30) were performed. The results suggest that the method and the age of the students have an effect on their understanding of the nature of models. A good understanding of the FC tasks as well as a convergence in the findings across the three methods was documented for grades eleven and twelve. This indicates that teachers can use the diagnostic instrument for an efficient and, at the same time, valid diagnosis for this group. Finally, the findings of this article may provide a possible explanation for alternative findings from previous studies as a result of specific methods that were used.

  12. Diagnosing Students' Understanding of the Nature of Models

    NASA Astrophysics Data System (ADS)

    Gogolin, Sarah; Krüger, Dirk

    2016-10-01

    Students' understanding of models in science has been subject to a number of investigations. The instruments the researchers used are suitable for educational research but, due to their complexity, cannot be employed directly by teachers. This article presents forced choice (FC) tasks, which, assembled as a diagnostic instrument, are supposed to measure students' understanding of the nature of models efficiently, while being sensitive enough to detect differences between individuals. In order to evaluate if the diagnostic instrument is suitable for its intended use, we propose an approach that complies with the demand to integrate students' responses to the tasks into the validation process. Evidence for validity was gathered based on relations to other variables and on students' response processes. Students' understanding of the nature of models was assessed using three methods: FC tasks, open-ended tasks and interviews (N = 448). Furthermore, concurrent think-aloud protocols (N = 30) were performed. The results suggest that the method and the age of the students have an effect on their understanding of the nature of models. A good understanding of the FC tasks as well as a convergence in the findings across the three methods was documented for grades eleven and twelve. This indicates that teachers can use the diagnostic instrument for an efficient and, at the same time, valid diagnosis for this group. Finally, the findings of this article may provide a possible explanation for alternative findings from previous studies as a result of specific methods that were used.

  13. Modelling direct tangible damages due to natural hazards

    NASA Astrophysics Data System (ADS)

    Kreibich, H.; Bubeck, P.

    2012-04-01

    Europe has witnessed a significant increase in direct damages from natural hazards. A further damage increase is expected due to the on-going accumulation of people and economic assets in risk-prone areas and the effects of climate change, for instance, on the severity and frequency of drought events in the Mediterranean basin. In order to mitigate the impact of natural hazards an improved risk management based on reliable risk analysis is needed. Particularly, there is still much research effort needed to improve the modelling of damage due to natural hazards. In comparison with hazard modelling, simple approaches still dominate damage assessments, mainly due to limitations in available data and knowledge on damaging processes and influencing factors. Within the EU-project ConHaz, methods as well as data sources and terminology for damage assessments were compiled, systemized and analysed. Similarities and differences between the approaches concerning floods, alpine hazards, coastal hazards and droughts were identified. Approaches for significant improvements of direct tangible damage modelling with a particular focus on cross-hazard-learning will be presented. Examples from different hazards and countries will be given how to improve damage data bases, the understanding of damaging processes, damage models and how to conduct improvements via validations and uncertainty analyses.

  14. Image Discrimination Models Predict Object Detection in Natural Backgrounds

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.; Rohaly, A. M.; Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Object detection involves looking for one of a large set of object sub-images in a large set of background images. Image discrimination models only predict the probability that an observer will detect a difference between two images. In a recent study based on only six different images, we found that discrimination models can predict the relative detectability of objects in those images, suggesting that these simpler models may be useful in some object detection applications. Here we replicate this result using a new, larger set of images. Fifteen images of a vehicle in an other-wise natural setting were altered to remove the vehicle and mixed with the original image in a proportion chosen to make the target neither perfectly recognizable nor unrecognizable. The target was also rotated about a vertical axis through its center and mixed with the background. Sixteen observers rated these 30 target images and the 15 background-only images for the presence of a vehicle. The likelihoods of the observer responses were computed from a Thurstone scaling model with the assumption that the detectabilities are proportional to the predictions of an image discrimination model. Three image discrimination models were used: a cortex transform model, a single channel model with a contrast sensitivity function filter, and the Root-Mean-Square (RMS) difference of the digital target and background-only images. As in the previous study, the cortex transform model performed best; the RMS difference predictor was second best; and last, but still a reasonable predictor, was the single channel model. Image discrimination models can predict the relative detectabilities of objects in natural backgrounds.

  15. Image Discrimination Models Predict Object Detection in Natural Backgrounds

    NASA Technical Reports Server (NTRS)

    Ahumada, Albert J., Jr.; Rohaly, A. M.; Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

    1994-01-01

    Object detection involves looking for one of a large set of object sub-images in a large set of background images. Image discrimination models only predict the probability that an observer will detect a difference between two images. In a recent study based on only six different images, we found that discrimination models can predict the relative detectability of objects in those images, suggesting that these simpler models may be useful in some object detection applications. Here we replicate this result using a new, larger set of images. Fifteen images of a vehicle in an other-wise natural setting were altered to remove the vehicle and mixed with the original image in a proportion chosen to make the target neither perfectly recognizable nor unrecognizable. The target was also rotated about a vertical axis through its center and mixed with the background. Sixteen observers rated these 30 target images and the 15 background-only images for the presence of a vehicle. The likelihoods of the observer responses were computed from a Thurstone scaling model with the assumption that the detectabilities are proportional to the predictions of an image discrimination model. Three image discrimination models were used: a cortex transform model, a single channel model with a contrast sensitivity function filter, and the Root-Mean-Square (RMS) difference of the digital target and background-only images. As in the previous study, the cortex transform model performed best; the RMS difference predictor was second best; and last, but still a reasonable predictor, was the single channel model. Image discrimination models can predict the relative detectabilities of objects in natural backgrounds.

  16. Marine Natural Products as Models to Circumvent Multidrug Resistance.

    PubMed

    Long, Solida; Sousa, Emília; Kijjoa, Anake; Pinto, Madalena M M

    2016-07-08

    Multidrug resistance (MDR) to anticancer drugs is a serious health problem that in many cases leads to cancer treatment failure. The ATP binding cassette (ABC) transporter P-glycoprotein (P-gp), which leads to premature efflux of drugs from cancer cells, is often responsible for MDR. On the other hand, a strategy to search for modulators from natural products to overcome MDR had been in place during the last decades. However, Nature limits the amount of some natural products, which has led to the development of synthetic strategies to increase their availability. This review summarizes the research findings on marine natural products and derivatives, mainly alkaloids, polyoxygenated sterols, polyketides, terpenoids, diketopiperazines, and peptides, with P-gp inhibitory activity highlighting the established structure-activity relationships. The synthetic pathways for the total synthesis of the most promising members and analogs are also presented. It is expected that the data gathered during the last decades concerning their synthesis and MDR-inhibiting activities will help medicinal chemists develop potential drug candidates using marine natural products as models which can deliver new ABC transporter inhibitor scaffolds.

  17. Naturally occurring animal models of human hepatitis E virus infection.

    PubMed

    Yugo, Danielle M; Cossaboom, Caitlin M; Meng, Xiang-Jin

    2014-01-01

    Hepatitis E virus (HEV) is a single-stranded, positive-sense RNA virus in the family Hepeviridae. Hepatitis E caused by HEV is a clinically important global disease. There are currently four well-characterized genotypes of HEV in mammalian species, although numerous novel strains of HEV likely belonging to either new genotypes or species have recently been identified from several other animal species. HEV genotypes 1 and 2 are limited to infection in humans, whereas genotypes 3 and 4 infect an expanding host range of animal species and are zoonotic to humans. Historical animal models include various species of nonhuman primates, which have been indispensable for the discovery of human HEV and for understanding its pathogenesis and course of infection. With the genetic identification and characterization of animal strains of HEV, a number of naturally occurring animal models such as swine, chicken, and rabbit have recently been developed for various aspects of HEV research, including vaccine trials, pathogenicity, cross-species infection, mechanism of virus replication, and molecular biology studies. Unfortunately, the current available animal models for HEV are still inadequate for certain aspects of HEV research. For instance, an animal model is still lacking to study the underlying mechanism of severe and fulminant hepatitis E during pregnancy. Also, an animal model that can mimic chronic HEV infection is critically needed to study the mechanism leading to chronicity in immunocompromised individuals. Genetic identification of additional novel animal strains of HEV may lead to the development of better naturally occurring animal models for HEV. This article reviews the current understanding of animal models of HEV infection in both natural and experimental infection settings and identifies key research needs and limitations. © The Author 2014. Published by Oxford University Press on behalf of the Institute for Laboratory Animal Research. All rights reserved. For

  18. Terminology model discovery using natural language processing and visualization techniques.

    PubMed

    Zhou, Li; Tao, Ying; Cimino, James J; Chen, Elizabeth S; Liu, Hongfang; Lussier, Yves A; Hripcsak, George; Friedman, Carol

    2006-12-01

    Medical terminologies are important for unambiguous encoding and exchange of clinical information. The traditional manual method of developing terminology models is time-consuming and limited in the number of phrases that a human developer can examine. In this paper, we present an automated method for developing medical terminology models based on natural language processing (NLP) and information visualization techniques. Surgical pathology reports were selected as the testing corpus for developing a pathology procedure terminology model. The use of a general NLP processor for the medical domain, MedLEE, provides an automated method for acquiring semantic structures from a free text corpus and sheds light on a new high-throughput method of medical terminology model development. The use of an information visualization technique supports the summarization and visualization of the large quantity of semantic structures generated from medical documents. We believe that a general method based on NLP and information visualization will facilitate the modeling of medical terminologies.

  19. Modeling of a coal-fired natural circulation boiler

    SciTech Connect

    Bhambare, K.S.; Mitra, S.K.; Gaitonde, U.N.

    2007-06-15

    Modeling of a natural circulation boiler for a coal-fired thermal power station is presented here. The boiler system is divided into seven subcomponents, and for each section, models based on conservation of mass, momentum, and energy are formulated. The pressure drop at various sections and the heat transfer coefficients are computed using empirical correlations. Solutions are obtained by using SIMULINK. The model is validated by comparing its steady state and dynamic responses with the actual plant data. Open loop responses of the model to the step changes in the operating parameters, such as pressure, temperature, steam flow, feed water flow, are also analyzed. The present model can be used for the development and design of effective boiler control systems.

  20. Rich-and-Poor Model for Human and Nature Interaction

    NASA Astrophysics Data System (ADS)

    Motesharrei, S.; Kalnay, E.; Rivas, J.; Rich-n-Poor

    2011-12-01

    Historical evidence shows collapse of several civilizations in different regions of the world. Jared Diamond presents an account of such societal failures in his 2005 book "Collapse: How Societies Choose to Fail or Succeed." As a precursor to building a complex model for interaction of human and environment, we developed a "thought-experiment" model based on Lotka-Volterra equations for the interaction of two species, known as the Predator-Prey model. We constructed a fairly simple rich-and-poor model that includes only four state variables (or stocks): Rich Population, Poor Population, Nature, and Rich Savings. We observed several scenarios for growth of societies by varying the model's parameter values, including scenarios that resemble the catastrophic fall of ancient civilizations such as the Maya and Anasazi.

  1. Towards a Curricular Model of the Nature of Science

    NASA Astrophysics Data System (ADS)

    Taber, Keith S.

    2008-02-01

    The nature of science is a complex theme, and continues to be the subject of advanced and ongoing scholarship, drawing upon a range of disciplines. Therefore, whatever is presented in school science as being ‘the’ nature of science must at best be a simplification, and so there is a need to form judgements about which simplifications are most appropriate. Effective ‘curricular models’ of science concepts are designed simplifications of scientific models that guide teachers by indicating target knowledge that is deemed appropriate in terms of the prior learning and conceptual development of a group of learners, and which is both ‘intellectually honest’ and a suitable basis for further learning. A similar approach can guide teaching about the nature of science. A consideration of the English National Curriculum offers an example of how aims relating to the teaching of the nature of science may not be realised in the absence of a suitable explicit curricular model to guide teaching.

  2. Irreversible inhibition of human cathepsins B, L, S and K by hypervalent tellurium compounds.

    PubMed

    Cunha, Rodrigo L O R; Gouvêa, Iuri E; Feitosa, Geovana P V; Alves, Márcio F M; Brömme, Dieter; Comasseto, João V; Tersariol, Ivarne L S; Juliano, Luiz

    2009-11-01

    The inhibition of human cysteine cathepsins B, L, S and K was evaluated by a set of hypervalent tellurium compounds (telluranes) comprising both organic and inorganic derivatives. All telluranes studied showed a time- and concentration-dependent irreversible inhibition of the cathepsins, and their second-order inactivation rate constants were determined. The organic derivatives were potent inhibitors of the cathepsins and clear specificities were detected, which were parallel to their known substrate specificities. In all cases, the activity of the tellurane-inhibited cathepsins was recovered by treatment of the inactivated enzymes with reducing agents. The maximum stoichiometry of the reaction between cysteine residues and telluranes were also determined. The presented data indicate that it is possible to design organic compounds with a tellurium(IV) moiety as a novel warhead that covalently modifies the catalytic cysteine, and which also form strong interactions with subsites of cathepsins B, L, S and K, resulting in more specific inhibition.

  3. Modelling of compositional flow in naturally fractured reservoirs

    SciTech Connect

    Chen, Zhangxin; Douglas, J. Jr.

    1996-12-31

    A double porosity model of multidimensional, multicomponent, three-phase flow in naturally fractured reservoirs is derived first on the basis of physical intuition and then by the mathematical theory of homogenization. A fully compositional model is considered when there are N chemical components, each of which may exist in any or all of the three phases: gas, oil, and water. The equations of the interaction between matrix and fracture systems are obtained from the mass, momentum, and energy balance laws and the entropy condition, and a mechanical potential tensor is introduced to describe the matrix boundary condition. Various types of flow in naturally fractured reservoirs are treated as particular cases of the present techniques.

  4. Modeling Aspects Of Nature Of Science To Preservice Elementary Teachers

    NASA Astrophysics Data System (ADS)

    Ashcraft, Paul

    2007-01-01

    Nature of science was modeled using guided inquiry activities in the university classroom with elementary education majors. A physical science content course initially used an Aristotelian model where students discussed the relationship between distance from a constant radiation source and the amount of radiation received based on accepted ``truths'' or principles and concluded that there was an inverse relationship. The class became Galilean in nature, using the scientific method to test that hypothesis. Examining data, the class rejected their hypothesis and concluded that there is an inverse square relationship. Assignments, given before and after the hypothesis testing, show the student's misconceptions and their acceptance of scientifically acceptable conceptions. Answers on exam questions further support this conceptual change. Students spent less class time on the inverse square relationship later when examining electrostatic force, magnetic force, gravity, and planetary solar radiation because the students related this particular experience to other physical relationships.

  5. Naturally Occurring Animal Models with Outer Retina Phenotypes

    PubMed Central

    Baehr, Wolfgang; Frederick, Jeanne M.

    2009-01-01

    Naturally occurring and laboratory generated animal models serve as powerful tools with which to investigate the etiology of human retinal degenerations, especially retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), cone dystrophies (CD) and macular degeneration (MD). Much progress has been made in elucidating gene defects underlying disease, in understanding mechanisms leading to disease, and in designing molecules for translational research and gene-based therapy to interfere with the progression of disease. Key to this progress has been study of naturally occurring murine and canine retinal degeneration mutants. This article will review the history, phenotypes and gene defects of select animal models with outer retina (photoreceptor and retinal pigment epithelium) degeneration phenotypes. PMID:19375447

  6. Natural hazard resilient cities: the case of a SSMS model

    NASA Astrophysics Data System (ADS)

    Santos-Reyes, Jaime

    2010-05-01

    Modern society is characterised by complexity; i.e. technical systems are highly complex and highly interdependent. The nature of the interdependence amongst these systems has become an issue on increasing importance in recent years. Moreover, these systems face a number threats ranging from technical, human and natural. For example, natural hazards (earthquakes, floods, heavy snow, etc) can cause significant problems and disruption to normal life. On the other hand, modern society depends on highly interdependent infrastructures such as transport (rail, road, air, etc), telecommunications, power and water supply, etc. Furthermore, in many cases there is no single owner, operator, and regulator of such systems. Any disruption in any of the interconnected systems may cause a domino-effect. The domino-effect may occur at local, regional or at national level; or, in some cases; it may be extended across international borders. Given the above, it may be argued that society is less resilient to such events and therefore there is a need to have a system in place able to maintain risk within an acceptable range, whatever that might be. This paper presents the modelling process of the interdependences amongst "critical infrastructures" (i.e. transport, telecommunications, power & water supply, etc) for a typical city. The approach has been the application of the developed Systemic Safety Management System (SSMS) model. The main conclusion is that the SSMS model has the potentiality to be used to model interdependencies amongst the so called "critical infrastructures". It is hoped that the approach presented in this paper may help to gain a better understanding of the interdependence amongst these systems and may contribute to a resilient society when disrupted by natural hazards.

  7. A Goal-Oriented Model of Natural Language Interaction

    DTIC Science & Technology

    1977-01-01

    AHSTKACT This report describes a research program in modeling human communication . The methodology involved selecting a single, naturally-occurring...knowledge is seldom used in the design process. Human communication skills have not bee’’ characferi?ed at a level of detail appropriate for guiding design...necessarily combine to give a complete picture of human communication . Experience over several more dialogues may suggest that one or all be replaced

  8. Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1998-01-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. Subsequent chapters of this report provide: an overview of NGTDM; a description of the interface between the NEMS and NGTDM; an overview of the solution methodology of the NGTDM; the solution methodology for the Annual Flow Module; the solution methodology for the Distributor Tariff Module; the solution methodology for the Capacity Expansion Module; the solution methodology for the Pipeline Tariff Module; and a description of model assumptions, inputs, and outputs.

  9. Models of natural fracture connectivity: Implications for reservoir permeability

    SciTech Connect

    Pollard, D.D. ); Aydin, A. )

    1991-03-01

    Fluid transport through a fracture network in rock depends strongly on the nature of connections between fracture segments and between individual fractures. We propose to develop three dimensional models for natural fracture connectivity using an integrated field, laboratory, and theoretical approach. We will investigate the mechanisms responsible for fracture connectivity (or lack thereof) for single and multiple sets of fractures. The models will be based on detailed field mapping and observations from both massive and layered sedimentary rocks, typical of producing oil and gas reservoirs. The mechanisms responsible for connectivity will be determined using continuum and fracture mechanics principles to construct computer simulations of the fracture process, including initiation, propagation, interaction, and termination of fractures under natural loading conditions. By identifying these mechanisms we will relate the degree of connectivity to the geometry, state of stress, and material properties of the reservoir rocks and, in turn, be in a position to evaluate the influence of these factors on fracture permeability in oil and gas reservoirs. A new initiative within the project is to use physically-based fracture simulations to address the question: does a length scale exist at which the fractured rock mass has a definable representative elementary volume (REV) with respect to fluid conductivity The results of our research will be complimentary to and help to constrain geophysical imaging techniques and geostatistical models for fractured petroleum reservoirs and should have important applications to hydrologic problems of contaminant transport in fractured aquifers. 5 figs.

  10. Medical Problem and Document Model for Natural Language Understanding

    PubMed Central

    Meystre, Stephane; Haug, Peter J.

    2003-01-01

    We are developing tools to help maintain a complete, accurate and timely problem list within a general purpose Electronic Medical Record system. As a part of this project, we have designed a system t o automatically retrieve medical problems from free-text documents. Here we describe an information model based on XML (eXtensible Markup Language) and compliant with the CDA (Clinical Document Architecture). This model is used to ease the exchange of clinical data between the Natural Language Understanding application that retrieves potential problems from narrative document, and the problem list management application. PMID:14728214

  11. Medical problem and document model for natural language understanding.

    PubMed

    Meystre, Stephanie; Haug, Peter J

    2003-01-01

    We are developing tools to help maintain a complete, accurate and timely problem list within a general purpose Electronic Medical Record system. As a part of this project, we have designed a system to automatically retrieve medical problems from free-text documents. Here we describe an information model based on XML (eXtensible Markup Language) and compliant with the CDA (Clinical Document Architecture). This model is used to ease the exchange of clinical data between the Natural Language Understanding application that retrieves potential problems from narrative document, and the problem list management application.

  12. Modeling insurer-homeowner interactions in managing natural disaster risk.

    PubMed

    Kesete, Yohannes; Peng, Jiazhen; Gao, Yang; Shan, Xiaojun; Davidson, Rachel A; Nozick, Linda K; Kruse, Jamie

    2014-06-01

    The current system for managing natural disaster risk in the United States is problematic for both homeowners and insurers. Homeowners are often uninsured or underinsured against natural disaster losses, and typically do not invest in retrofits that can reduce losses. Insurers often do not want to insure against these losses, which are some of their biggest exposures and can cause an undesirably high chance of insolvency. There is a need to design an improved system that acknowledges the different perspectives of the stakeholders. In this article, we introduce a new modeling framework to help understand and manage the insurer's role in catastrophe risk management. The framework includes a new game-theoretic optimization model of insurer decisions that interacts with a utility-based homeowner decision model and is integrated with a regional catastrophe loss estimation model. Reinsurer and government roles are represented as bounds on the insurer-insured interactions. We demonstrate the model for a full-scale case study for hurricane risk to residential buildings in eastern North Carolina; present the results from the perspectives of all stakeholders-primary insurers, homeowners (insured and uninsured), and reinsurers; and examine the effect of key parameters on the results.

  13. Forecasting natural aquifer discharge using a numerical model and convolution.

    PubMed

    Boggs, Kevin G; Johnson, Gary S; Van Kirk, Rob; Fairley, Jerry P

    2014-01-01

    If the nature of groundwater sources and sinks can be determined or predicted, the data can be used to forecast natural aquifer discharge. We present a procedure to forecast the relative contribution of individual aquifer sources and sinks to natural aquifer discharge. Using these individual aquifer recharge components, along with observed aquifer heads for each January, we generate a 1-year, monthly spring discharge forecast for the upcoming year with an existing numerical model and convolution. The results indicate that a forecast of natural aquifer discharge can be developed using only the dominant aquifer recharge sources combined with the effects of aquifer heads (initial conditions) at the time the forecast is generated. We also estimate how our forecast will perform in the future using a jackknife procedure, which indicates that the future performance of the forecast is good (Nash-Sutcliffe efficiency of 0.81). We develop a forecast and demonstrate important features of the procedure by presenting an application to the Eastern Snake Plain Aquifer in southern Idaho.

  14. Modeling Natural Space Ionizing Radiation Effects on External Materials

    NASA Technical Reports Server (NTRS)

    Alstatt, Richard L.; Edwards, David L.; Parker, Nelson C. (Technical Monitor)

    2000-01-01

    Predicting the effective life of materials for space applications has become increasingly critical with the drive to reduce mission cost. Programs have considered many solutions to reduce launch costs including novel, low mass materials and thin thermal blankets to reduce spacecraft mass. Determining the long-term survivability of these materials before launch is critical for mission success. This presentation will describe an analysis performed on the outer layer of the passive thermal control blanket of the Hubble Space Telescope. This layer had degraded for unknown reasons during the mission, however ionizing radiation (IR) induced embrittlement was suspected. A methodology was developed which allowed direct comparison between the energy deposition of the natural environment and that of the laboratory generated environment. Commercial codes were used to predict the natural space IR environment model energy deposition in the material from both natural and laboratory IR sources, and design the most efficient test. Results were optimized for total and local energy deposition with an iterative spreadsheet. This method has been used successfully for several laboratory tests at the Marshall Space Flight Center. The study showed that the natural space IR environment, by itself, did not cause the premature degradation observed in the thermal blanket.

  15. The light {\\varvec{U}} boson as the mediator of a new force, coupled to a combination of {\\varvec{Q, B, L}} and dark matter

    NASA Astrophysics Data System (ADS)

    Fayet, Pierre

    2017-01-01

    A new light gauge boson U may have both vector and axial couplings. In a large class of theories, however, the new U(1) current J^μ _F naturally combines with the weak neutral current J^μ _{Z_sm}, both parity-violating, into a vectorial current J^μ _U, combination of the B, L and electromagnetic currents with a possible dark-matter current. U^μ may be expressed equivalently as cos ξ C^μ + sin ξ Z^μ _ sm ("mixing with the Z") or (1/cos χ ) {hat{C}}^μ + tan χ A^μ ("mixing with the photon"), with {hat{C}} coupled to B, L and dark matter. The U boson may be viewed as a generalized dark photon, coupled to SM particles through Q_U=Q+λ _B B+λ _i L_i, with strength g''cos ξ cos ^2θ =etan χ . "Kinetic-mixing" terms, gauge invariant or not, simply correspond to a description in a non-orthogonal field basis (rather than to a new physical effect), with the dark photon in general also coupled to B and L. In a grand-unified theory Q_U^gut=Q-2 (B-L) at the GUT scale for SM particles, invariant under the SU(4) electrostrong symmetry group, with a non-vanishing ɛ = tan χ already present at the GUT scale, leading to Q_U˜eq Q-1.64 (B-L) at low energy. This also applies, for a very light or massless U boson, to a new long-range force, which could show up through apparent violations of the equivalence principle.

  16. Natural Alignment in the Two Higgs Doublet Model

    NASA Astrophysics Data System (ADS)

    Bhupal Dev, P. S.; Pilaftsis, Apostolos

    2017-07-01

    As the LHC Higgs data persistently suggest the couplings of the observed 125 GeV Higgs boson to be consistent with the Standard Model (SM) expectations, any extended Higgs sector must lead to the so-called SM alignment limit, where one of the Higgs bosons behaves exactly like that of the SM. In the context of the Two Higgs Doublet Model (2HDM), this alignment is often associated with either decoupling of the heavy Higgs sector or accidental cancellations in the 2HDM potential. We present a novel symmetry justification for ‘natural’ alignment without necessarily decoupling or fine-tuning. We show that there exist only three different symmetry realizations of the natural alignment scenario in 2HDM. We identify the 2HDM parameter space satisfying the natural alignment condition up to the Planck scale. We also analyze new collider signals for the heavy Higgs sector in the natural alignment limit, which dominantly lead to third-generation quarks in the final state and can serve as a useful observational tool during the Run-II phase of the LHC.

  17. Current Methods of Natural Hazards Communication used within Catastrophe Modelling

    NASA Astrophysics Data System (ADS)

    Dawber, C.; Latchman, S.

    2012-04-01

    In the field of catastrophe modelling, natural hazards need to be explained every day to (re)insurance professionals so that they may understand estimates of the loss potential of their portfolio. The effective communication of natural hazards to city professionals requires different strategies to be taken depending on the audience, their prior knowledge and respective backgrounds. It is best to have at least three sets of tools in your arsenal for a specific topic, 1) an illustration/animation, 2) a mathematical formula and 3) a real world case study example. This multi-faceted approach will be effective for those that learn best by pictorial means, mathematical means or anecdotal means. To show this we will use a set of real examples employed in the insurance industry of how different aspects of natural hazards and the uncertainty around them are explained to city professionals. For example, explaining the different modules within a catastrophe model such as the hazard, vulnerability and loss modules. We highlight how recent technology such as 3d plots, video recording and Google Earth maps, when used properly can help explain concepts quickly and easily. Finally we also examine the pitfalls of using overly-complicated visualisations and in general how counter-intuitive deductions may be made.

  18. THE PENA BLANCA NATURAL ANALOGUE PERFORMANCE ASSESSMENT MODEL

    SciTech Connect

    G. Saulnier and W. Statham

    2006-04-16

    The Nopal I uranium mine in the Sierra Pena Blanca, Chihuahua, Mexico serves as a natural analogue to the Yucca Mountain repository. The Pena Blanca Natural Analogue Performance Assessment Model simulates the mobilization and transport of radionuclides that are released from the mine and transported to the saturated zone. The Pena Blanca Natural Analogue Performance Assessment Model uses probabilistic simulations of hydrogeologic processes that are analogous to the processes that occur at the Yucca Mountain site. The Nopal I uranium deposit lies in fractured, welded, and altered rhyolitic ash-flow tuffs that overlie carbonate rocks, a setting analogous to the geologic formations at the Yucca Mountain site. The Nopal I mine site has the following analogous characteristics as compared to the Yucca Mountain repository site: (1) Analogous source--UO{sub 2} uranium ore deposit = spent nuclear fuel in the repository; (2) Analogous geology--(i.e. fractured, welded, and altered rhyolitic ash-flow tuffs); (3) Analogous climate--Semiarid to arid; (4) Analogous setting--Volcanic tuffs overlie carbonate rocks; and (5) Analogous geochemistry--Oxidizing conditions Analogous hydrogeology: The ore deposit lies in the unsaturated zone above the water table.

  19. THE PENA BLANCA NATURAL ANALOGUE PERFORMANCE ASSESSMENT MODEL

    SciTech Connect

    G.J. Saulnier Jr; W. Statham

    2006-03-10

    The Nopal I uranium mine in the Sierra Pena Blanca, Chihuahua, Mexico serves as a natural analogue to the Yucca Mountain repository. The Pena Blanca Natural Analogue Performance Assessment Model simulates the mobilization and transport of radionuclides that are released from the mine and transported to the saturated zone. the Pena Blanca Natural Analogue Model uses probabilistic simulations of hydrogeologic processes that are analogous to the processes that occur at the Yucca Mountain site. The Nopal I uranium deposit lies in fractured, welded, and altered rhyolitic ash flow tuffs that overlie carbonate rocks, a setting analogous to the geologic formations at the Yucca Mountain site. The Nopal I mine site has the following characteristics as compared to the Yucca Mountain repository site. (1) Analogous source: UO{sub 2} uranium ore deposit = spent nuclear fuel in the repository; (2) Analogous geologic setting: fractured, welded, and altered rhyolitic ash flow tuffs overlying carbonate rocks; (3) Analogous climate: Semiarid to arid; (4) Analogous geochemistry: Oxidizing conditions; and (5) Analogous hydrogeology: The ore deposit lies in the unsaturated zone above the water table. The Nopal I deposit is approximately 8 {+-} 0.5 million years old and has been exposed to oxidizing conditions during the last 3.2 to 3.4 million years. The Pena Blanca Natural Analogue Model considers that the uranium oxide and uranium silicates in the ore deposit were originally analogous to uranium-oxide spent nuclear fuel. The Pena Blanca site has been characterized using field and laboratory investigations of its fault and fracture distribution, mineralogy, fracture fillings, seepage into the mine adits, regional hydrology, and mineralization that shows the extent of radionuclide migration. Three boreholes were drilled at the Nopal I mine site in 2003 and these boreholes have provided samples for lithologic characterization, water-level measurements, and water samples for laboratory

  20. Spatial Durbin model analysis macroeconomic loss due to natural disasters

    NASA Astrophysics Data System (ADS)

    Kusrini, D. E.; Mukhtasor

    2015-03-01

    Magnitude of the damage and losses caused by natural disasters is huge for Indonesia, therefore this study aimed to analyze the effects of natural disasters for macroeconomic losses that occurred in 115 cities/districts across Java during 2012. Based on the results of previous studies it is suspected that it contains effects of spatial dependencies in this case, so that the completion of this case is performed using a regression approach to the area, namely Analysis of Spatial Durbin Model (SDM). The obtained significant predictor variable is population, and predictor variable with a significant weighting is the number of occurrences of disasters, i.e., disasters in the region which have an impact on other neighboring regions. Moran's I index value using the weighted Queen Contiguity also showed significant results, meaning that the incidence of disasters in the region will decrease the value of GDP in other.

  1. Peromyscus mice as a model for studying natural variation

    PubMed Central

    Bedford, Nicole L; Hoekstra, Hopi E

    2015-01-01

    The deer mouse (genus Peromyscus) is the most abundant mammal in North America, and it occupies almost every type of terrestrial habitat. It is not surprising therefore that the natural history of Peromyscus is among the best studied of any small mammal. For decades, the deer mouse has contributed to our understanding of population genetics, disease ecology, longevity, endocrinology and behavior. Over a century's worth of detailed descriptive studies of Peromyscus in the wild, coupled with emerging genetic and genomic techniques, have now positioned these mice as model organisms for the study of natural variation and adaptation. Recent work, combining field observations and laboratory experiments, has lead to exciting advances in a number of fields—from evolution and genetics, to physiology and neurobiology. DOI: http://dx.doi.org/10.7554/eLife.06813.001 PMID:26083802

  2. The Power of Natural Variation for Model Organism Biology.

    PubMed

    Gasch, Audrey P; Payseur, Bret A; Pool, John E

    2016-03-01

    Genetic background effects have long been recognized and, in some cases studied, but they are often viewed as a nuisance by molecular biologists. We suggest that genetic variation currently represents a critical frontier for molecular studies. Human genetics has seen a surge of interest in genetic variation and its contributions to disease, but insights into disease mechanisms are difficult since information about gene function is lacking. By contrast, model organism genetics has excelled at revealing molecular mechanisms of cellular processes, but often de-emphasizes genetic variation and its functional consequences. We argue that model organism biology would benefit from incorporating natural variation, both to capture how well laboratory lines exemplify the species they represent and to inform on molecular processes and their variability. Such a synthesis would also greatly expand the relevance of model systems for studies of complex trait variation, including disease.

  3. Turing Systems: A General Model for Complex Patterns in Nature

    NASA Astrophysics Data System (ADS)

    Barrio, R. A.

    More than half a century ago Alan Turing showed that a system of nonlinear reaction-diffusion equations could produce spatial patterns that are stationary and robust, a phenomenon known as "diffusion driven instability". This remarkable fact was largely ignored for twenty years. However, in the last decade, Turing systems have been a matter of intense and active research, because they are suitable to model a wide variety of phenomena found in Nature, ranging from Turing's original idea of describing morphogenesis from an egg, and applications to the colouring of skins of animals, to the physics of chemical reactors and catalyzers, the physiology of the heart, semiconductor devices, and even to geological formations. In this paper I review the main properties of the Turing instability using a generic reaction-diffusion model, and I give examples of recent applications of Turing models to different problems of pattern formation.

  4. Numerical Modelling of Extreme Natural Hazards in the Russian Seas

    NASA Astrophysics Data System (ADS)

    Arkhipkin, Victor; Dobrolyubov, Sergey; Korablina, Anastasia; Myslenkov, Stanislav; Surkova, Galina

    2017-04-01

    Storm surges and extreme waves are severe natural sea hazards. Due to the almost complete lack of natural observations of these phenomena in the Russian seas (Caspian, Black, Azov, Baltic, White, Barents, Okhotsk, Kara), especially about their formation, development and destruction, they have been studied using numerical simulation. To calculate the parameters of wind waves for the seas listed above, except the Barents Sea, the spectral model SWAN was applied. For the Barents and Kara seas we used WAVEWATCH III model. Formation and development of storm surges were studied using ADCIRC model. The input data for models - bottom topography, wind, atmospheric pressure and ice cover. In modeling of surges in the White and Barents seas tidal level fluctuations were used. They have been calculated from 16 harmonic constant obtained from global atlas tides FES2004. Wind, atmospheric pressure and ice cover was taken from the NCEP/NCAR reanalysis for the period from 1948 to 2010, and NCEP/CFSR reanalysis for the period from 1979 to 2015. In modeling we used both regular and unstructured grid. The wave climate of the Caspian, Black, Azov, Baltic and White seas was obtained. Also the extreme wave height possible once in 100 years has been calculated. The statistics of storm surges for the White, Barents and Azov Seas were evaluated. The contribution of wind and atmospheric pressure in the formation of surges was estimated. The technique of climatic forecast frequency of storm synoptic situations was developed and applied for every sea. The research was carried out with financial support of the RFBR (grant 16-08-00829).

  5. Physical vulnerability modelling in natural hazard risk assessment

    NASA Astrophysics Data System (ADS)

    Douglas, J.

    2007-04-01

    An evaluation of the risk to an exposed element from a hazardous event requires a consideration of the element's vulnerability, which expresses its propensity to suffer damage. This concept allows the assessed level of hazard to be translated to an estimated level of risk and is often used to evaluate the risk from earthquakes and cyclones. However, for other natural perils, such as mass movements, coastal erosion and volcanoes, the incorporation of vulnerability within risk assessment is not well established and consequently quantitative risk estimations are not often made. This impedes the study of the relative contributions from different hazards to the overall risk at a site. Physical vulnerability is poorly modelled for many reasons: the cause of human casualties (from the event itself rather than by building damage); lack of observational data on the hazard, the elements at risk and the induced damage; the complexity of the structural damage mechanisms; the temporal and geographical scales; and the ability to modify the hazard level. Many of these causes are related to the nature of the peril therefore for some hazards, such as coastal erosion, the benefits of considering an element's physical vulnerability may be limited. However, for hazards such as volcanoes and mass movements the modelling of vulnerability should be improved by, for example, following the efforts made in earthquake risk assessment. For example, additional observational data on induced building damage and the hazardous event should be routinely collected and correlated and also numerical modelling of building behaviour during a damaging event should be attempted.

  6. Naturalness of CP Violation in the Standard Model

    SciTech Connect

    Gibbons, Gary W.; Gielen, Steffen; Pope, C. N.; Turok, Neil

    2009-03-27

    We construct a natural measure on the space of Cabibbo-Kobayashi-Maskawa matrices in the standard model, assuming the fermion mass matrices are randomly selected from a distribution which incorporates the observed quark mass hierarchy. This measure allows us to assess the likelihood of Jarlskog's CP violation parameter J taking its observed value J{approx_equal}3x10{sup -5}. We find that the observed value, while well below the mathematically allowed maximum, is in fact typical once the observed quark masses are assumed.

  7. Natural State Models of the Geysers Geothermal System

    NASA Astrophysics Data System (ADS)

    Brikowski, T.; Norton, D.; Blackwell, D.

    2001-12-01

    Summarized in the following report are the results obtained in a project focused on natural state (pre-production) modeling of The Geysers geothermal system. The project was motivated by a need to better-understand the origin, current state, and future scenarios for The Geysers to allow better management of this unique energy resource. During the three-year course of the project nine reviewed papers were published, and six oral presentations made to communicate these results to the industrial and academic geothermal communities. Preprints of the papers are attached as appendices, and form the bulk of the material in this report.

  8. Gauged B-L symmetry and baryogenesis via leptogenesis at TeV scale

    SciTech Connect

    Sahu, Narendra; Yajnik, Urjit A.

    2005-01-15

    It is shown that the requirement of preservation of baryon asymmetry does not rule out a scale for leptogenesis as low as 10 TeV. The conclusions are compatible with see-saw mechanism if, for example, the pivot mass scale for neutrinos is {approx_equal}10{sup -2} that of the charged leptons. We explore the parameter space m-tilde{sub 1}- M{sub 1} of relevant light and heavy neutrino masses by solving Boltzmann equations. A viable scenario for obtaining baryogenesis in this way is presented in the context of gauged B-L symmetry.

  9. Human task animation from performance models and natural language input

    NASA Technical Reports Server (NTRS)

    Esakov, Jeffrey; Badler, Norman I.; Jung, Moon

    1989-01-01

    Graphical manipulation of human figures is essential for certain types of human factors analyses such as reach, clearance, fit, and view. In many situations, however, the animation of simulated people performing various tasks may be based on more complicated functions involving multiple simultaneous reaches, critical timing, resource availability, and human performance capabilities. One rather effective means for creating such a simulation is through a natural language description of the tasks to be carried out. Given an anthropometrically-sized figure and a geometric workplace environment, various simple actions such as reach, turn, and view can be effectively controlled from language commands or standard NASA checklist procedures. The commands may also be generated by external simulation tools. Task timing is determined from actual performance models, if available, such as strength models or Fitts' Law. The resulting action specification are animated on a Silicon Graphics Iris workstation in real-time.

  10. Modeling Natural Attenuation of an Industrial Facility in Houston

    NASA Astrophysics Data System (ADS)

    Sun, D.

    2016-12-01

    Groundwater monitoring is currently ongoing at a commercial/industrial facility located in Deer Park, Texas (the site). The subject site is an approximate 10 acre commercial/industrial facility that began operation in the late-1970s. Operations have historically consisted of vehicle maintenance services, administrative, and equipment storage. Assessment and groundwater monitoring activities have been conducted at the site to evaluate the magnitude and extent of groundwater affected with chlorinated volatile organic compounds (VOCs). Groundwater data has been collected at this site since the mid-2000s on a quarterly basis. Presently, VOC constituents tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-dichloroethene (DCE), 1,1-dichloroethene (1,1-DCE), and vinyl chloride (VC) are the only chemicals of concern (COCs) detected at concentrations exceeding the TCEQ Actions Levels established by the state of Texas. The goal is that one day the site will receive a certificate of completion from the state, which states that all non-responsible parties are released from all liability to the state for cleanup. The remediation technology that is currently being used at this site is Monitoring Natural Attenuation (MNA). A significant question is whether MNA is efficiently removing COCs in groundwater and how long will this process take to achieve the remediation goals. The objective of this study is to provide an estimate of concentrations of COCs in groundwater at the site using the Biochlor model. The Biochlor model will help answer the question as to whether or not natural attenuation is occurring at the site efficiently. Results show that Monitored Natural Attenuation may not be the optimal remediation technology to use at this site. Other remedial technologies are needed to clean up chemical in the site. Groundwater monitoring is currently ongoing at a commercial/industrial facility located in Deer Park, Texas (the site). The subject site is an approximate 10 acre

  11. Numerical modeling of natural and ventilated cavitating flows

    NASA Astrophysics Data System (ADS)

    Qin, Qiao

    Cavitation is a phenomenon that frequently occurs in fluid-handling machinery, ranging from all types of pumps, turbines, and propellers to various piping systems and hydraulic structures. Cavitation research has been pursued for over a century and an enormous quantity of literature on cavitation has been generated. Cavitation modeling is challenging and is still in the development stage due to its inherent complexity of the physics involved. There are basically three objectives in this thesis work. First, an existing virtual single-phase natural cavitation model is used to extensively explore the unsteadiness of sheet/cloud cavitation on two hydrofoils (NACA 0015 and CAV2003). Five discrete vortex shedding mechanisms are identified in this research. Second, this existing virtual single-phase natural cavitation model is further modified to take into account the effect of incondensable gas that comes out of solution due to the cavitation evaporation process. This was motivated by the observation that the computed mean velocity distribution in the wake of a cavitating hydrofoil, without the effect of incondensable gas, agrees well with experimental data close to the trailing edge but deviates systematically further downstream. This revision shows a significant improvement on the computed mean velocity distribution in the wake compared to that without the incondensable gas effect and the results are in agreement with those from experiments. These are two new findings that are absent in literature. Third, a two-phase, fully compressible flow model based on Large Eddy Simulation (LES) for ventilated cavitating flows is developed and is successfully implemented in the simulation of an axisymmetric underwater body.

  12. The natural defense system and the normative self model.

    PubMed

    Kourilsky, Philippe

    2016-01-01

    Infectious agents are not the only agressors, and the immune system is not the sole defender of the organism. In an enlarged perspective, the 'normative self model' postulates that a 'natural defense system' protects man and other complex organisms against the environmental and internal hazards of life, including infections and cancers. It involves multiple error detection and correction mechanisms that confer robustness to the body at all levels of its organization. According to the model, the self relies on a set of physiological norms, and NONself (meaning : Non Obedient to the Norms of the self) is anything 'off-norms'. The natural defense system comprises a set of 'civil defenses' (to which all cells in organs and tissues contribute), and a 'professional army ', made of a smaller set of mobile cells. Mobile and non mobile cells differ in their tuning abilities. Tuning extends the recognition capabilities of NONself by the mobile cells, which increase their defensive function. To prevent them to drift, which would compromise self/NONself discrimination, the more plastic mobile cells need to periodically refer to the more stable non mobile cells to keep within physiological standards.

  13. Natural State Model of the Nesjavellir Geothermal Field, Iceland

    SciTech Connect

    Bodvarsson, G.S.; Pruess, K.; Stefansson, V.; Steingrimsson, B.; Bjornsson, S.; Gunnarsson, A.; Gunnlaugsson, E.

    1986-01-21

    The Nesjavellir geothermal system in southern Iceland is very complex from both a thermal and hydrologic point of view. There are large pressure and temperature gradients in the wellfield and zones with drastically different pressure potentials. Thus, natural fluid flow is substantial in the system and flow patterns are complex. We have developed a two-dimensional natural state model for the Nesjavellir system that matches reasonably well the observed pressure and temperature distributions. The match with field data has allowed determination of the energy recharge to the system and the permeability distribution. Fluids recharge the system at rate of 0.02 kg/s/m with an enthalpy of 1460 kJ/kg. The permeability in the main reservoir is estimated to be in the range of 1.5 to 2.0 md, which agrees well with injection test results from individual wells. Permeabilities in shallower reservoirs are about an order of magnitude higher. Most of the main reservoir is under twephase conditions, as are shallow aquifers in the southern part of the field. The model results also suggest that the low temperatures in the shallow part of the northern region of the field may be due to the young age of the system; i.e., the system is gradually heating up. If this is the case the estimated age of the system near the wellfield is on the order of a few thousand years.

  14. Integrated modeling of natural and human systems - problems and initiatives

    NASA Astrophysics Data System (ADS)

    Kessler, H.; Giles, J.; Gunnink, J.; Hughes, A.; Moore, R. V.; Peach, D.

    2009-12-01

    Governments and their executive agencies across the world are facing increasing pressure to make decisions about the management of resources in light of population growth and environmental change. In the UK and the Netherlands, for example, groundwater is becoming a scarce resource for large parts of its most densely populated areas. At the same time river and groundwater flooding resulting from high rainfall events are increasing in scale and frequency and sea level rise is threatening the defences of coastal cities. There is also a need for affordable housing, improved transport infrastructure and waste disposal as well as sources of renewable energy and sustainable food production. These challenges can only be resolved if solutions are based on sound scientific evidence. Although we have knowledge and understanding of many individual processes in the natural sciences it is clear that a single science discipline is unable to answer the questions and their inter-relationships. Modern science increasingly employs computer models to simulate the natural, economic and human system. Management and planning requires scenario modelling, forecasts and “predictions”. Although the outputs are often impressive in terms of apparent accuracy and visualisation, they are inherently not suited to simulate the response to feedbacks from other models of the earth system, such as the impact of human actions. Geological Survey Organisations (GSO) are increasingly employing advances in Information Technology to visualise and improve their understanding of geological systems. Instead of 2 dimensional paper maps and reports many GSOs now produce 3 dimensional geological framework models and groundwater flow models as their standard output. Additionally the British Geological Survey and the Geological Survey of the Netherlands have developed standard routines to link geological data to groundwater models, but these models are only aimed at solving one specific part of the earth

  15. Climate and weather risk in natural resource models

    NASA Astrophysics Data System (ADS)

    Merrill, Nathaniel Henry

    This work, consisting of three manuscripts, addresses natural resource management under risk due to variation in climate and weather. In three distinct but theoretically related applications, I quantify the role of natural resources in stabilizing economic outcomes. In Manuscript 1, we address policy designed to effect the risk of cyanobacteria blooms in a drinking water reservoir through watershed wide policy. Combining a hydrologic and economic model for a watershed in Rhode Island, we solve for the efficient allocation of best management practices (BMPs) on livestock pastures to meet a monthly risk-based as well as mean-based water quality objective. In order to solve for the efficient allocations of nutrient control effort, we optimize a probabilistically constrained integer-programming problem representing the choices made on each farm and the resultant conditions that support cyanobacteria blooms. In doing so, we employ a genetic algorithm (GA). We hypothesize that management based on controlling the upper tail of the probability distribution of phosphorus loading implies different efficient management actions as compared to controlling mean loading. We find a shift to more intense effort on fewer acres when a probabilistic objective is specified with cost savings of meeting risk levels of up to 25% over mean loading based policies. Additionally, we illustrate the relative cost effectiveness of various policies designed to meet this risk-based objective. Rainfall and the subsequent overland runoff is the source of transportation of nutrients to a receiving water body, with larger amounts of phosphorus moving in more intense rainfall events. We highlight the importance of this transportation mechanism by comparing policies under climate change scenarios, where the intensity of rainfall is projected to increase and the time series process of rainfall to change. In Manuscript 2, we introduce a new economic groundwater model that incorporates the gradual shift

  16. Natural variations of lithium isotopes in a mammalian model.

    PubMed

    Balter, Vincent; Vigier, Nathalie

    2014-03-01

    Despite lithium's extensive clinical applications, the cellular and molecular basis for the therapeutic effects remains to be elucidated. The large difference in mass between the two lithium isotopes ((6)Li and (7)Li) has prompted biochemists to explore the metabolism of Li by using pure (6)Li and (7)Li labeled drugs. However, experiments were carried out at very high Li concentrations, which did not reflect natural conditions. In the present study, we consider, for the first time, the natural variations of the (7)Li/(6)Li ratio in the organs and body fluids of an animal model, sheep. Each organ seems to be characterized by a specific Li isotope composition. So far, the range of the (7)Li/(6)Li ratio in the sheep body, expressed as δ permil variations relative to the L-SVEC standard (δ(7)Li), is about 40‰, between muscles (∼40‰) and kidney (∼0‰). Relative to a dietary δ(7)Li value of ∼+17‰, serum, red blood cells, muscle, liver, brain and kidney have a (7)Li enrichment of -12‰, -14‰, +22‰, +5‰, -3‰ and -15‰, respectively. The Li isotope composition is likely to be fractionated during intestinal absorption, with a greater absorption of (6)Li relative to (7)Li. According to previous conclusions obtained with (6)Li and (7)Li labeled chemicals, (6)Li appears to diffuse into erythrocytes faster than does (7)Li. However, this does not hold for myocytes and hepatocytes, because these two tissues have a higher δ(7)Li level than serum. Purely diffusive isotopic fractionation would leave all organs (7)Li-depleted relative to the serum, which is not the case, suggesting that active, molecule-specific, isotopic fractionation occurs in the body. Our preliminary results suggest that natural Li isotope variations can shed light on its regulation in the body, being active or passive.

  17. Using Digital Learning Objects to Introduce Students to the Nature of Models and the Nature of Matter

    ERIC Educational Resources Information Center

    Gustafson, Brenda; Mahaffy, Peter; Martin, Brian

    2011-01-01

    This article reports a subset of findings from a larger study centered on designing a series of six digital learning objects to help Grade 5 (age 10-12) students begin to consider the nature of models (understood as the physical or mental representation of objects, phenomena, or processes), the particle nature of matter, and the behavior of…

  18. Using Digital Learning Objects to Introduce Students to the Nature of Models and the Nature of Matter

    ERIC Educational Resources Information Center

    Gustafson, Brenda; Mahaffy, Peter; Martin, Brian

    2011-01-01

    This article reports a subset of findings from a larger study centered on designing a series of six digital learning objects to help Grade 5 (age 10-12) students begin to consider the nature of models (understood as the physical or mental representation of objects, phenomena, or processes), the particle nature of matter, and the behavior of…

  19. Tank bromeliad - a natural model ecosystem for methane cycling research

    NASA Astrophysics Data System (ADS)

    Martinson, Guntars; Brandt, Franziska; Conrad, Ralf

    2014-05-01

    Tank bromeliads are common epiphytes throughout neotropical forest ecosystems. They are relatively small discrete habitats for terrestrial and aquatic macro- and microorganisms and naturally replicated. Their tanks effectively collect leaf litter and water and harbor a diverse microbial community. Up to several thousands of these tank bromeliads per hectare of tropical forest create a unique wetland ecosystem responsible for significant methane emissions. In a field study in tropical montane forests of southern Ecuador we sampled tank bromeliads of different species, size and canopy height and found that tank water availability controlled community composition of methanogenic archaea, determined by molecular analysis of the archaeal 16S rRNA genes. We set up a greenhouse experiment to investigate drying and re-wetting effects on microbial community composition and methanogenesis. Additionally, we conducted 13-CH-4 and 13-CO-2 labeling studies to investigate potential interaction of plant and microbial metabolism during methane cycling in tank bromeliads. Drying resulted in rapid change of the microbial community composition. The relative abundance of acetoclastic methanogens increased and that of hydrogenotrophic methanogens decreased with decreasing tank water availability confirming our field observations. Labeling studies showed that carbon was released from the plant into the tank supporting methanogenesis and that tank-produced methane was ventilated through the bromeliad leaf structure into the atmosphere which is analogous to the rhizosphere environment of wetland ecosystems. The bromeliad ecosystem may therefore provide a natural model to study how environmental changes and plant-microbe interactions drive methane cycling in aquatic-terrestrial ecosystems.

  20. Modeling and mitigating natural hazards: Stationarity is immortal!

    NASA Astrophysics Data System (ADS)

    Montanari, Alberto; Koutsoyiannis, Demetris

    2014-12-01

    Environmental change is a reason of relevant concern as it is occurring at an unprecedented pace and might increase natural hazards. Moreover, it is deemed to imply a reduced representativity of past experience and data on extreme hydroclimatic events. The latter concern has been epitomized by the statement that "stationarity is dead." Setting up policies for mitigating natural hazards, including those triggered by floods and droughts, is an urgent priority in many countries, which implies practical activities of management, engineering design, and construction. These latter necessarily need to be properly informed, and therefore, the research question on the value of past data is extremely important. We herein argue that there are mechanisms in hydrological systems that are time invariant, which may need to be interpreted through data inference. In particular, hydrological predictions are based on assumptions which should include stationarity. In fact, any hydrological model, including deterministic and nonstationary approaches, is affected by uncertainty and therefore should include a random component that is stationary. Given that an unnecessary resort to nonstationarity may imply a reduction of predictive capabilities, a pragmatic approach, based on the exploitation of past experience and data is a necessary prerequisite for setting up mitigation policies for environmental risk.

  1. The natural defense system and the normative self model

    PubMed Central

    Kourilsky, Philippe

    2016-01-01

    Infectious agents are not the only agressors, and the immune system is not the sole defender of the organism. In an enlarged perspective, the ‘normative self model’ postulates that a ‘natural defense system’ protects man and other complex organisms against the environmental and internal hazards of life, including infections and cancers. It involves multiple error detection and correction mechanisms that confer robustness to the body at all levels of its organization. According to the model, the self relies on a set of physiological norms, and NONself (meaning : Non Obedient to the Norms of the self) is anything ‘off-norms’. The natural defense system comprises a set of ‘civil defenses’ (to which all cells in organs and tissues contribute), and a ‘professional army ‘, made of a smaller set of mobile cells. Mobile and non mobile cells differ in their tuning abilities. Tuning extends the recognition capabilities of NONself by the mobile cells, which increase their defensive function. To prevent them to drift, which would compromise self/NONself discrimination, the more plastic mobile cells need to periodically refer to the more stable non mobile cells to keep within physiological standards. PMID:27303629

  2. An efficient perceived contrast evaluation model for natural images

    NASA Astrophysics Data System (ADS)

    Chen, Qiao Song; Kim, Choon-Woo

    2010-01-01

    Perceived image contrast is one of the major factors affecting the image quality on displays. Various methods have been proposed to measure the image contrast. However, image contrasts in most of previous works are focused on B/W and defined on simple patterns such as sinusoidal grating. This paper introduces a perceived contrast evaluation model for natural color images. In pursuit of high accuracy, both global and local contrasts are taken into account. Global contrast indicates difference in the perceived luminance and chroma. Local contrast describes the distinguishable degree in image details. In the proposed method, global contrast is calculated based on the dynamic ranges in lightness and chroma. Local contrast is obtained by gradient computations. Both of the global and local contrasts are merged to achieve the perceived contrast. Two types of performance evaluations are performed. They are cross content and within content evaluations. Results of experiments show that global contrast is more effective in the cross content evaluation where the contrast differences between different natural color images are examined. For both of the cross and within content evaluations, the proposed measure yields high value of correlation coefficient with the subjective scores from human visual tests.

  3. Modeling monochloramine loss in the presence of natural organic matter.

    PubMed

    Duirk, Stephen E; Gombert, Bertrand; Croué, Jean-Philippe; Valentine, Richard L

    2005-09-01

    A comprehensive model describing monochloramine loss in the presence of natural organic matter (NOM) is presented. The model incorporates simultaneous monochloramine autodecomposition and reaction pathways resulting in NOM oxidation. These competing pathways were resolved numerically using an iterative process evaluating hypothesized reactions describing NOM oxidation by monochloramine under various experimental conditions. The reaction of monochloramine with NOM was described as biphasic using four NOM specific reaction parameters. NOM pathway 1 involves a direct reaction of monochloramine with NOM (k(doc1) = 1.05 x 10(4)-3.45 x 10(4) M(-1) h(-1)). NOM pathway 2 is slower in terms of monochloramine loss and attributable to free chlorine (HOCl) derived from monochloramine hydrolysis (k(doc2) = 5.72 x 10(5)-6.98 x 10(5) M(-1) h(-1)), which accounted for the majority of monochloramine loss. Also, the free chlorine reactive site fraction in the NOM structure was found to correlate to specific ultraviolet absorbance at 280 nm (SUVA280). Modeling monochloramine loss allowed for insight into disinfectant reaction pathways involving NOM oxidation. This knowledge is of value in assessing monochloramine stability in distribution systems and reaction pathways leading to disinfection by-product (DBP) formation.

  4. Response to natural disturbance and attack in a trade model

    NASA Astrophysics Data System (ADS)

    Su, Bei-Bei; Xu, Tian; He, Da-Ren

    2005-03-01

    We suggest a trade model, which may describe the trade activities between the open ports along Yangzi River. The cumulative distribution of the quantities of port export and import, generalized by the model, shows a good agreement with our statistical results over 229 open ports. Randomly select a port and let its production decrease greatly by a fixed ratio (a disturbance), we find that the averaged quantities of port export and import increase obviously. This means that, in a healthy trade network, a lot of elements can make benefits when one of them is hit by a natural calamity. When select the port that has most trade relationship with others and let its production decrease greatly by a fixed ratio (an attack), we find that the averaged quantities of port export and import soon recovers and reach the original value. This healthy response will significantly change if the trade rules in the model are only slightly revised. This result may suggest a feature, which can distinguish healthy complex systems from others.

  5. Modeling of information flows in natural gas storage facility

    NASA Astrophysics Data System (ADS)

    Ranjbari, Leyla; Bahar, Arifah; Aziz, Zainal Abdul

    2013-09-01

    The paper considers the natural-gas storage valuation based on the information-based pricing framework of Brody-Hughston-Macrina (BHM). As opposed to many studies which the associated filtration is considered pre-specified, this work tries to construct the filtration in terms of the information provided to the market. The value of the storage is given by the sum of the discounted expectations of the cash flows under risk-neutral measure, conditional to the constructed filtration with the Brownian bridge noise term. In order to model the flow of information about the cash flows, we assume the existence of a fixed pricing kernel with liquid, homogenous and incomplete market without arbitrage.

  6. Modeling of natural organic matter transport processes in groundwater.

    PubMed Central

    Yeh, T C; Mas-Pla, J; McCarthy, J F; Williams, T M

    1995-01-01

    A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the site was obtained using slug tests. The transport of a conservative tracer (chloride) was successfully reproduced using these conductivity data. Despite the good simulation of the flow field, NOM breakthrough curves could not be reproduced using a two-site sorption model with spatially constant parameters. Preliminary results suggest that different mechanisms for the adsorption/desorption processes, as well as their spatial variability, may significantly affect the transport and fate of NOM. PMID:7621798

  7. Modeling Gene-Environment Interactions With Quasi-Natural Experiments.

    PubMed

    Schmitz, Lauren; Conley, Dalton

    2017-02-01

    This overview develops new empirical models that can effectively document Gene × Environment (G×E) interactions in observational data. Current G×E studies are often unable to support causal inference because they use endogenous measures of the environment or fail to adequately address the nonrandom distribution of genes across environments, confounding estimates. Comprehensive measures of genetic variation are incorporated into quasi-natural experimental designs to exploit exogenous environmental shocks or isolate variation in environmental exposure to avoid potential confounders. In addition, we offer insights from population genetics that improve upon extant approaches to address problems from population stratification. Together, these tools offer a powerful way forward for G×E research on the origin and development of social inequality across the life course.

  8. Using natural laboratories and modeling to decipher lithospheric rheology

    NASA Astrophysics Data System (ADS)

    Sobolev, Stephan

    2013-04-01

    Rheology is obviously important for geodynamic modeling but at the same time rheological parameters appear to be least constrained. Laboratory experiments give rather large ranges of rheological parameters and their scaling to nature is not entirely clear. Therefore finding rheological proxies in nature is very important. One way to do that is finding appropriate values of rheological parameter by fitting models to the lithospheric structure in the highly deformed regions where lithospheric structure and geologic evolution is well constrained. Here I will present two examples of such studies at plate boundaries. One case is the Dead Sea Transform (DST) that comprises a boundary between African and Arabian plates. During the last 15- 20 Myr more than 100 km of left lateral transform displacement has been accumulated on the DST and about 10 km thick Dead Sea Basin (DSB) was formed in the central part of the DST. Lithospheric structure and geological evolution of DST and DSB is rather well constrained by a number of interdisciplinary projects including DESERT and DESIRE projects leaded by the GFZ Potsdam. Detailed observations reveal apparently contradictory picture. From one hand widespread igneous activity, especially in the last 5 Myr, thin (60-80 km) lithosphere constrained from seismic data and absence of seismicity below the Moho, seem to be quite natural for this tectonically active plate boundary. However, surface heat flow of less than 50-60mW/m2 and deep seismicity in the lower crust ( deeper than 20 km) reported for this region are apparently inconsistent with the tectonic settings specific for an active continental plate boundary and with the crustal structure of the DSB. To address these inconsistencies which comprise what I call the "DST heat-flow paradox", a 3D numerical thermo-mechanical model was developed operating with non-linear elasto-visco-plastic rheology of the lithosphere. Results of the numerical experiments show that the entire set of

  9. The EL mouse: a natural model of autism and epilepsy.

    PubMed

    Meidenbauer, Joshua J; Mantis, John G; Seyfried, Thomas N

    2011-02-01

    Autism is a multifactorial disorder that involves impairments in social interactions and communication, as well as restricted and repetitive behaviors. About 30% of individuals with autism develop epilepsy by adulthood. The EL mouse has long been studied as a natural model of multifactorial idiopathic generalized epilepsy with complex partial seizures. Because epilepsy is a comorbid trait of autism, we evaluated the EL mouse for behaviors associated with autism. We compared the behavior of EL mice to age-matched control DDY mice, a genetically related nonepileptic strain. The mice were compared in the open field and in the light-dark compartment tests to measure activity, exploratory behavior, and restricted and repetitive behaviors. The social transmission of food preference test was employed to evaluate social communication. Home-cage behavior was also evaluated in EL and DDY mice as a measure of repetitive activity. We found that EL mice displayed several behavioral abnormalities characteristic of autism. Impairments in social interaction and restricted patterns of interest were evident in EL mice. Activity, exploratory behavior, and restricted behavior were significantly greater in EL mice than in DDY mice. EL mice exhibited impairment in the social transmission of food preference assay. In addition, a stereotypic myoclonic jumping behavior was observed in EL mice, but was not seen in DDY mice. It is of interest to note that seizure activity within 24 h of testing exacerbated the autistic behavioral abnormalities found in EL mice. These findings suggest that the EL mouse expresses behavioral abnormalities similar to those seen in persons with autism. We propose that the EL mouse can be utilized as a natural model of autism and epilepsy. Wiley Periodicals, Inc. © 2010 International League Against Epilepsy.

  10. Modeling of Marine Natural Hazards in the Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Zahibo, Narcisse; Nikolkina, Irina; Pelinovsky, Efim

    2010-05-01

    The Caribbean Sea countries are often affected by various marine natural hazards: hurricanes and cyclones, tsunamis and flooding. The historical data of marine natural hazards for the Lesser Antilles and specially, for Guadeloupe are presented briefly. Numerical simulation of several historical tsunamis in the Caribbean Sea (1755 Lisbon trans-Atlantic tsunami, 1867 Virgin Island earthquake tsunami, 2003 Montserrat volcano tsunami) are performed within the framework of the nonlinear-shallow theory. Numerical results demonstrate the importance of the real bathymetry variability with respect to the direction of propagation of tsunami wave and its characteristics. The prognostic tsunami wave height distribution along the Caribbean Coast is computed using various forms of seismic and hydrodynamics sources. These results are used to estimate the far-field potential for tsunami hazards at coastal locations in the Caribbean Sea. The nonlinear shallow-water theory is also applied to model storm surges induced by tropical cyclones, in particular, cyclones "Lilli" in 2002 and "Dean" in 2007. Obtained results are compared with observed data. The numerical models have been tested against known analytical solutions of the nonlinear shallow-water wave equations. Obtained results are described in details in [1-7]. References [1] N. Zahibo and E. Pelinovsky, Natural Hazards and Earth System Sciences, 1, 221 (2001). [2] N. Zahibo, E. Pelinovsky, A. Yalciner, A. Kurkin, A. Koselkov and A. Zaitsev, Oceanologica Acta, 26, 609 (2003). [3] N. Zahibo, E. Pelinovsky, A. Kurkin and A. Kozelkov, Science Tsunami Hazards. 21, 202 (2003). [4] E. Pelinovsky, N. Zahibo, P. Dunkley, M. Edmonds, R. Herd, T. Talipova, A. Kozelkov and I. Nikolkina, Science of Tsunami Hazards, 22, 44 (2004). [5] N. Zahibo, E. Pelinovsky, E. Okal, A. Yalciner, C. Kharif, T. Talipova and A. Kozelkov, Science of Tsunami Hazards, 23, 25 (2005). [6] N. Zahibo, E. Pelinovsky, T. Talipova, A. Rabinovich, A. Kurkin and I

  11. Model reactions and natural occurrence of furans from hypersaline environments

    NASA Astrophysics Data System (ADS)

    Krause, T.; Tubbesing, C.; Benzing, K.; Schöler, H. F.

    2014-05-01

    Volatile organic compounds like furan and its derivatives are important for atmospheric properties and reactions. In this work the known abiotic formation of furan from catechol under Fenton-like conditions with Fe3+ sulfate was revised by the use of a bispidine Fe2+ complex as a model compound for iron with well-known characteristics. While total yields were comparable to those with the Fe3+ salt, the bispidine Fe2+ complex is a better catalyst as the turnover numbers of the active iron species were higher. Additionally, the role of iron and pH is discussed in relation to furan formation from model compounds and in natural sediment and water samples collected from the Dead Sea and several salt lakes in Western Australia. Various alkylated furans and even traces of halogenated furans (3-chlorofuran and 3-bromofuran) were found in some Australian samples. 3-chlorofuran was found in three sediments and four water samples, whereas 3-bromofuran was detected in three water samples. Further, the emission of furans is compared to the abundance of several possible precursors such as isoprene and aromatic hydrocarbons as well as to the related thiophenes. It is deduced that the emissions of volatile organic compounds such as furans contribute to the formation of ultra-fine particles in the vicinity of salt lakes and are important for the local climate.

  12. Pathogenesis of a Model Gammaherpesvirus in a Natural Host ▿

    PubMed Central

    Hughes, David J.; Kipar, Anja; Sample, Jeffery T.; Stewart, James P.

    2010-01-01

    Murine gammaherpesvirus 68 (MHV-68) infection of laboratory mice (Mus musculus) is an established model of gammaherpesvirus pathogenesis. The fact that M. musculus is not a host in the wild prompted us to reassess MHV-68 infection in wood mice (Apodemus sylvaticus), a natural host. Here, we report significant differences in MHV-68 infection in the two species: (i) following intranasal inoculation, MHV-68 replicated in the lungs of wood mice to levels approximately 3 log units lower than in BALB/c mice; (ii) in BALB/c mice, virus replication in alveolar epithelial cells was accompanied by a diffuse, T-cell-dominated interstitial pneumonitis, whereas in wood mice it was restricted to focal granulomatous infiltrations; (iii) within wood mice, latently infected lymphocytes were abundant in inducible bronchus-associated lymphoid tissue that was not apparent in BALB/c mice; (iv) splenic latency was established in both species, but well-delineated secondary follicles with germinal centers were present in wood mice, while only poorly delineated follicles were seen in BALB/c mice; and, perhaps as a consequence, (v) production of neutralizing antibody was significantly higher in wood mice. These differences highlight the value of this animal model in the study of MHV-68 pathogenesis. PMID:20130062

  13. Models of natural fracture connectivity: Implication for reservoir permeability

    SciTech Connect

    Aydin, A.

    1992-03-01

    We have investigated common mechanisms responsible for fracture connectivity (or lack thereof) for single and multiple sets of fractures. The methods of study were based on detailed field mapping of fractures in layered sedimentary rocks, typical of producing oil and gas reservoirs and on numerical modeling of the concepts developed from the field observations. The crucial mechanisms important for connectivity have been deduced to be fracture propagation across layer interfaces with or without shearing in slightly deformed terrains in the Appalachians Plateau, central New York, and in highly deformed terrains in the Valley and Ridge province of the Appalachians in northeastern Tennessee, northwestern North Carolina and southwestern Maryland. Both of these mechanisms have been simulated by using numerical models which include fracture propagation across interfaces between dissimilar layers, and interactions between parallel faults of various scales. Fluid transport through a single fracture or a fracture network in rock depends strongly on the nature of connections between fracture segments and between the individual fractures. This study has shown that layer interfaces, particularly those with thin shale layers impede fluid flow along fractures in vertical direction, whereas additional fractures between low angle faults along the interfaces enhance it.

  14. Development of a natural gas systems analysis model (GSAM)

    SciTech Connect

    1999-10-01

    This report provides an overview of the activities to date and schedule for future testing, validation, and authorized enhancements of Natural Gas Systems Analysis Model (GSAM). The goal of this report is to inform DOE managers of progress in model development and to provide a benchmark for ongoing and future research. Section II of the report provides a detailed discussion on the major GSAM development programs performed and completed during the period of performance, July 1, 1998 to September 30, 1999. Key improvements in the new GSAM version are summarized in Section III. Programmer's guides for GSAM main modules were produced to provide detailed descriptions of all major subroutines and main variables of the computer code. General logical flowcharts of the subroutines are also presented in the guides to provide overall picture of interactions between the subroutines. A standard structure of routine explanation is applied in every programmer's guide. The explanation is started with a brief description or main purpose of the routine, lists of input and output files read and created, and lists of invoked/child and calling/parent routines. In some of the guides, interactions between the routine itself and its parent and child routines are presented in the form of graphical flowchart. The explanation is then proceeded with step by step description of computer code in the subroutine where each step delegates a section of related code. Between steps, if a certain section of code needs further explanation, a Note is inserted with relevant explanation.

  15. Genetic signatures of natural selection in a model invasive ascidian

    PubMed Central

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-01-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta. PMID:28266616

  16. Genetic signatures of natural selection in a model invasive ascidian

    NASA Astrophysics Data System (ADS)

    Lin, Yaping; Chen, Yiyong; Yi, Changho; Fong, Jonathan J.; Kim, Won; Rius, Marc; Zhan, Aibin

    2017-03-01

    Invasive species represent promising models to study species’ responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified “plastic” genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta.

  17. Insights From Natural Host-Parasite Interactions: The Drosophila Model

    PubMed Central

    Keebaugh, Erin S.; Schlenke, Todd A.

    2013-01-01

    Immune responses against opportunistic pathogens have been extensively studied in Drosophila, leading to a detailed map of the genetics behind innate immunity networks including the Toll, Imd, Jak-Stat, and JNK pathways. However, immune mechanisms of other organisms, particularly plants, have primarily been investigated using natural pathogens. It was the use of natural pathogens in plant research that revealed the plant R/Avr system, a specialized immune response derived from antagonistic coevolution between plant immune proteins and their natural pathogens’ virulence proteins. Thus, we recommend that researchers begin to use natural Drosophila pathogens to identify novel immune mechanisms that may have arisen through antagonistic coevolution with common natural pathogens. In this review, we address the benefits of using natural pathogens in research, describe the known natural pathogens of Drosophila, and discuss exciting prospects for future research on select natural pathogens of Drosophila. PMID:23764256

  18. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    SciTech Connect

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Frauk; Hughes, Richard G.

    2001-08-15

    Research continues on characterizing and modeling the behavior of naturally fractured reservoir systems. Work has progressed on developing techniques for estimating fracture properties from seismic and well log data, developing naturally fractured wellbore models, and developing a model to characterize the transfer of fluid from the matrix to the fracture system for use in the naturally fractured reservoir simulator.

  19. Natural gas production problems : solutions, methodologies, and modeling.

    SciTech Connect

    Rautman, Christopher Arthur; Herrin, James M.; Cooper, Scott Patrick; Basinski, Paul M.; Olsson, William Arthur; Arnold, Bill Walter; Broadhead, Ronald F.; Knight, Connie D.; Keefe, Russell G.; McKinney, Curt; Holm, Gus; Holland, John F.; Larson, Rich; Engler, Thomas W.; Lorenz, John Clay

    2004-10-01

    Natural gas is a clean fuel that will be the most important domestic energy resource for the first half the 21st centtuy. Ensuring a stable supply is essential for our national energy security. The research we have undertaken will maximize the extractable volume of gas while minimizing the environmental impact of surface disturbances associated with drilling and production. This report describes a methodology for comprehensive evaluation and modeling of the total gas system within a basin focusing on problematic horizontal fluid flow variability. This has been accomplished through extensive use of geophysical, core (rock sample) and outcrop data to interpret and predict directional flow and production trends. Side benefits include reduced environmental impact of drilling due to reduced number of required wells for resource extraction. These results have been accomplished through a cooperative and integrated systems approach involving industry, government, academia and a multi-organizational team within Sandia National Laboratories. Industry has provided essential in-kind support to this project in the forms of extensive core data, production data, maps, seismic data, production analyses, engineering studies, plus equipment and staff for obtaining geophysical data. This approach provides innovative ideas and technologies to bring new resources to market and to reduce the overall environmental impact of drilling. More importantly, the products of this research are not be location specific but can be extended to other areas of gas production throughout the Rocky Mountain area. Thus this project is designed to solve problems associated with natural gas production at developing sites, or at old sites under redevelopment.

  20. Mathematical modeling of stable carbon isotope ratios in natural gases^@?

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Perry, J. K.; Jenden, P. D.; Schoell, M.

    2000-08-01

    models with laboratory data for specific study areas. With this approach isotope data of natural gases can be used not only to estimate the time of gas generation in a sedimentary basin, but also to evaluate the source rock maturities at which specific accumulations were generated, and place constraints on trap charging histories.

  1. Nature

    NASA Astrophysics Data System (ADS)

    Heinhorst, Sabine; Cannon, Gordon

    1997-01-01

    The fact that two of the original articles by this year's Nobel laureates were published in Nature bears witness to the pivotal role of this journal in documenting pioneering discoveries in all areas of science. The prize for Physiology or Medicine was awarded to immunologists Peter C. Doherty (University of Tennessee) and Rolf M. Zinkernagel (University of Zurich, Switzerland), honoring work that, in the 1970s, laid the foundation for our current understanding of the way in which our immune system differentiates between healthy cells and virus-infected ones that are targeted for destruction (p 465 in the October 10 issue of vol. 383). Three researchers share the Chemistry award for their discovery of C60 buckminsterfullerenes. The work by Robert Curl, Richard Smalley (both at Rice University), and Harry Kroto (University of Sussex, UK) has led to a burst of new approaches to materials development and in carbon chemistry (p 561 of the October 17 issue of vol. 383). This year's Nobel prize in physics went to three U.S. researchers, Douglas Osheroff (Stanford University) and David M. Lee and Robert C. Richardson (Cornell University), who were honored for their work on superfluidity, a frictionless liquid state, of supercooled 3He (p 562 of the October 17 issue of vol. 383).

  2. Natural gas transmission and distribution model of the National Energy Modeling System

    SciTech Connect

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

  3. Towards a continuous population model for natural language vowel shift.

    PubMed

    Shipman, Patrick D; Faria, Sérgio H; Strickland, Christopher

    2013-09-07

    The Great English Vowel Shift of 16th-19th centuries and the current Northern Cities Vowel Shift are two examples of collective language processes characterized by regular phonetic changes, that is, gradual changes in vowel pronunciation over time. Here we develop a structured population approach to modeling such regular changes in the vowel systems of natural languages, taking into account learning patterns and effects such as social trends. We treat vowel pronunciation as a continuous variable in vowel space and allow for a continuous dependence of vowel pronunciation in time and age of the speaker. The theory of mixtures with continuous diversity provides a framework for the model, which extends the McKendrick-von Foerster equation to populations with age and phonetic structures. We develop the general balance equations for such populations and propose explicit expressions for the factors that impact the evolution of the vowel pronunciation distribution. For illustration, we present two examples of numerical simulations. In the first one we study a stationary solution corresponding to a state of phonetic equilibrium, in which speakers of all ages share a similar phonetic profile. We characterize the variance of the phonetic distribution in terms of a parameter measuring a ratio of phonetic attraction to dispersion. In the second example we show how vowel shift occurs upon starting with an initial condition consisting of a majority pronunciation that is affected by an immigrant minority with a different vowel pronunciation distribution. The approach developed here for vowel systems may be applied also to other learning situations and other time-dependent processes of cognition in self-interacting populations, like opinions or perceptions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Competition between B-Z and B-L transitions in a single DNA molecule: Computational studies

    NASA Astrophysics Data System (ADS)

    Kwon, Ah-Young; Nam, Gi-Moon; Johner, Albert; Kim, Seyong; Hong, Seok-Cheol; Lee, Nam-Kyung

    2016-02-01

    Under negative torsion, DNA adopts left-handed helical forms, such as Z-DNA and L-DNA. Using the random copolymer model developed for a wormlike chain, we represent a single DNA molecule with structural heterogeneity as a helical chain consisting of monomers which can be characterized by different helical senses and pitches. By Monte Carlo simulation, where we take into account bending and twist fluctuations explicitly, we study sequence dependence of B-Z transitions under torsional stress and tension focusing on the interaction with B-L transitions. We consider core sequences, (GC) n repeats or (TG) n repeats, which can interconvert between the right-handed B form and the left-handed Z form, imbedded in a random sequence, which can convert to left-handed L form with different (tension dependent) helical pitch. We show that Z-DNA formation from the (GC) n sequence is always supported by unwinding torsional stress but Z-DNA formation from the (TG) n sequence, which are more costly to convert but numerous, can be strongly influenced by the quenched disorder in the surrounding random sequence.

  5. Model operating permits for natural gas processing plants

    SciTech Connect

    Arend, C.

    1995-12-31

    Major sources as defined in Title V of the Clean Air Act Amendments of 1990 that are required to submit an operating permit application will need to: Evaluate their compliance status; Determine a strategic method of presenting the general and specific conditions of their Model Operating Permit (MOP); Maintain compliance with air quality regulations. A MOP is prepared to assist permitting agencies and affected facilities in the development of operating permits for a specific source category. This paper includes a brief discussion of example permit conditions that may be applicable to various types of Title V sources. A MOP for a generic natural gas processing plant is provided as an example. The MOP should include a general description of the production process and identify emission sources. The two primary elements that comprise a MOP are: Provisions of all existing state and/or local air permits; Identification of general and specific conditions for the Title V permit. The general provisions will include overall compliance with all Clean Air Act Titles. The specific provisions include monitoring, record keeping, and reporting. Although Title V MOPs are prepared on a case-by-case basis, this paper will provide a general guideline of the requirements for preparation of a MOP. Regulatory agencies have indicated that a MOP included in the Title V application will assist in preparation of the final permit provisions, minimize delays in securing a permit, and provide support during the public notification process.

  6. Modelling the costs of natural hazards in games

    NASA Astrophysics Data System (ADS)

    Bostenaru-Dan, M.

    2012-04-01

    City are looked for today, including a development at the University of Torino called SimTorino, which simulates the development of the city in the next 20 years. The connection to another games genre as video games, the board games, will be investigated, since there are games on construction and reconstruction of a cathedral and its tower and a bridge in an urban environment of the middle ages based on the two novels of Ken Follett, "Pillars of the Earth" and "World Without End" and also more recent games, such as "Urban Sprawl" or the Romanian game "Habitat", dealing with the man-made hazard of demolition. A review of these games will be provided based on first hand playing experience. In games like "World without End" or "Pillars of the Earth", just like in the recently popular games of Zynga on social networks, construction management is done through providing "building" an item out of stylised materials, such as "stone", "sand" or more specific ones as "nail". Such approach could be used also for retrofitting buildings for earthquakes, in the series of "upgrade", not just for extension as it is currently in games, and this is what our research is about. "World without End" includes a natural disaster not so analysed today but which was judged by the author as the worst of manhood: the Black Death. The Black Death has effects and costs as well, not only modelled through action cards, but also on the built environment, by buildings remaining empty. On the other hand, games such as "Habitat" rely on role playing, which has been recently recognised as a way to bring games theory to decision making through the so-called contribution of drama, a way to solve conflicts through balancing instead of weighting, and thus related to Analytic Hierarchy Process. The presentation aims to also give hints on how to design a game for the problem of earthquake retrofit, translating the aims of the actors in such a process into role playing. Games are also employed in teaching of urban

  7. Modeling Modern Methane Emissions from Natural Wetlands. 1; Model Description and Results

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin; Matthews, Elaine

    2001-01-01

    Methane is an important greenhouse gas which contributes about 22 percent to the present greenhouse effect. Natural wetlands currently constitute the biggest methane source and were the major source in preindustrial times. Wetland emissions depend highly on the climate, i.e., on soil temperature and water table. To investigate the response of methane emissions from natural wetlands to climate variations, a process-based model that derives methane emissions from natural wetlands as a function of soil temperature, water table, and net primary productivity is used. For its application on the global scale, global data sets for all model parameters are generated. In addition, a simple hydrologic model is developed in order to simulate the position of the water table in wetlands. The hydrologic model is tested against data from different wetland sites, and the sensitivity of the hydrologic model to changes in precipitation is examined. The global methane­ hydrology model constitutes a tool to study temporal and spatial variations in methane emissions from natural wetlands. The model is applied using high-frequency atmospheric forcing fields from European Center for Medium-range Weather Forecasts (ECMWF) re-analyses of the period from 1982 to 1993. We calculate global annual methane emissions from wetlands to be 260 teragrams per year. Twenty-five percent of these methane emissions originate from wetlands north of 30 degrees North Latitude. Only 60 percent of the produced methane is emitted, while the rest is re-oxidized. A comparison of zonal integrals of simulated global wetland emissions and results obtained by an inverse modeling approach shows good agreement. In a test with data from two wetlands the seasonality of simulated and observed methane emissions agrees well.

  8. Modeling Modern Methane Emissions from Natural Wetlands. 1; Model Description and Results

    NASA Technical Reports Server (NTRS)

    Walter, Bernadette P.; Heimann, Martin; Matthews, Elaine

    2001-01-01

    Methane is an important greenhouse gas which contributes about 22 percent to the present greenhouse effect. Natural wetlands currently constitute the biggest methane source and were the major source in preindustrial times. Wetland emissions depend highly on the climate, i.e., on soil temperature and water table. To investigate the response of methane emissions from natural wetlands to climate variations, a process-based model that derives methane emissions from natural wetlands as a function of soil temperature, water table, and net primary productivity is used. For its application on the global scale, global data sets for all model parameters are generated. In addition, a simple hydrologic model is developed in order to simulate the position of the water table in wetlands. The hydrologic model is tested against data from different wetland sites, and the sensitivity of the hydrologic model to changes in precipitation is examined. The global methane­ hydrology model constitutes a tool to study temporal and spatial variations in methane emissions from natural wetlands. The model is applied using high-frequency atmospheric forcing fields from European Center for Medium-range Weather Forecasts (ECMWF) re-analyses of the period from 1982 to 1993. We calculate global annual methane emissions from wetlands to be 260 teragrams per year. Twenty-five percent of these methane emissions originate from wetlands north of 30 degrees North Latitude. Only 60 percent of the produced methane is emitted, while the rest is re-oxidized. A comparison of zonal integrals of simulated global wetland emissions and results obtained by an inverse modeling approach shows good agreement. In a test with data from two wetlands the seasonality of simulated and observed methane emissions agrees well.

  9. A robust and flexible Geospatial Modeling Interface (GMI) for deploying and evaluating natural resource models

    USDA-ARS?s Scientific Manuscript database

    Geographical information systems (GIS) software packages have been used for nearly three decades as analytical tools in natural resource management for geospatial data assembly, processing, storage, and visualization of input data and model output. However, with increasing availability and use of fu...

  10. Adjudicating the Debate Over Two Models of Nature Appreciation

    ERIC Educational Resources Information Center

    Lintott, Sheila

    2004-01-01

    This essay discusses the similarities and the differences between aesthetic appreciation of nature and of art, and canvasses attempts to delineate the scope of appropriate aesthetic appreciation of nature. It begins with a presentation of Kendall Walton's theory of appropriate art appreciation and explores its implications, specifically his…

  11. Opinion: The use of natural hazard modeling for decision making under uncertainty

    Treesearch

    David E. Calkin; Mike Mentis

    2015-01-01

    Decision making to mitigate the effects of natural hazards is a complex undertaking fraught with uncertainty. Models to describe risks associated with natural hazards have proliferated in recent years. Concurrently, there is a growing body of work focused on developing best practices for natural hazard modeling and to create structured evaluation criteria for complex...

  12. Biomimetics: using nature as an inspiring model for human innovation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2006-01-01

    The evolution of nature over 3.8 billion years led to the highly effective and power efficient biological mechanisms. Imitating these mechanisms offers enormous potentials for the improvement of our life and the tools we use.

  13. Tracer flow model for naturally fractured geothermal reservoirs

    SciTech Connect

    Ramirez, Jetzabeth; Rivera, Jesus; Rodriquez, Fernando

    1988-01-01

    The model proposed has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The reservoir is treated as being composed of two regions: a mobile region where diffusion and convection take place and a stagnant or immobile region where only diffusion and adsorption are allowed. Solutions to the basic equations in the Laplace space were derived for tracer injection and were numerically inverted using the Stehfest algorithm. Even though numerical dispersion is present in these solutions, starting at moderate dimensionless time values, a definite trend was found as to infer the behavior of the system under different flow conditions. For practical purposes, it was found that he size of the matrix blocks does not seem to affect the tracer concentration reponse and the solution became equivalent to that previously presented by Tang et al. Under these conditions, the behavior of the system can be described by two dimensionless parameters: the Peclet number for the fractures, P{sub e{sup 1}}, and a parameter {alpha} ({alpha} = {xi}{sqrt}P{sub e{sup 2}}), where {xi} is {xi} = {phi}{sub e} D{sub e}/v(w-{delta}) and P{sub e{sup 2}} is the Peclet number for the matrix. Tracer response for spike injection was also derived in this work. A limiting analytical solution was found for the case of {alpha} approaching zero and a given P{sub e{sup 1}}, which corresponds to the case of a homogeneous system. It is shown that this limiting solution is valid for {alpha} < 10{sup -2}. For the case of continuous injection this solution reduces to that previously presented by Coats and Smith. For the spike solution it was found that the breakthrough time for maximum tracer concentration is directly related to the dimensionless group ({sqrt}(9 + (X{sub D}){sup 2}(P{sub e{sup 1}}){sup 2}) -3)/P{sub e{sup 1}}. Therefore it is possible to obtain the value of P{sub e{sup 1}} or X{sub D}. A set of graphs of dimensionless concentration in the fracture vs

  14. Conceptual geoinformation model of natural hazards risk assessment

    NASA Astrophysics Data System (ADS)

    Kulygin, Valerii

    2016-04-01

    Natural hazards are the major threat to safe interactions between nature and society. The assessment of the natural hazards impacts and their consequences is important in spatial planning and resource management. Today there is a challenge to advance our understanding of how socio-economical and climate changes will affect the frequency and magnitude of hydro-meteorological hazards and associated risks. However, the impacts from different types of natural hazards on various marine and coastal economic activities are not of the same type. In this study, the conceptual geomodel of risk assessment is presented to highlight the differentiation by the type of economic activities in extreme events risk assessment. The marine and coastal ecosystems are considered as the objects of management, on the one hand, and as the place of natural hazards' origin, on the other hand. One of the key elements in describing of such systems is the spatial characterization of their components. Assessment of ecosystem state is based on ecosystem indicators (indexes). They are used to identify the changes in time. The scenario approach is utilized to account for the spatio-temporal dynamics and uncertainty factors. Two types of scenarios are considered: scenarios of using ecosystem services by economic activities and scenarios of extreme events and related hazards. The reported study was funded by RFBR, according to the research project No. 16-35-60043 mol_a_dk.

  15. Natural language dialogue in an integrated computational model

    SciTech Connect

    Frederking, R.E.

    1986-01-01

    The computational system presented here, Psli3, uses the uniform framework of a production-system architecture to carry out natural language understanding and generation in a well-integrated way. This is demonstrated primarily using intersentential ellipsis resolution, in addition to examples of definite reference resolution, in addition to examples of definite reference resolution and interactive error correction. The system's conversational context arises naturally as the result of the persistence of the internal representations of previous utterances in working memory. Natural language input is interpreted within this framework using a modification of the syntactic technique of chart parsing, extended to include semantics, and adapted to the production-system architecture. It provides a graceful way of handling ambiguity within this architecture, and allows separate knowledge sources to interact smoothly across different utterances in a highly integrated fashion. The design of this system demonstrates how flexible and natural-user interactions can be carried out using a system with a naturally flexible control structure. A processing-based taxonomy for ellipsis resolution developed is used to analyze the coverage of intersentential ellipsis.

  16. Natural language modeling for phoneme-to-text transcription

    SciTech Connect

    Derouault, A.M.; Merialdo, B.

    1986-11-01

    This paper relates different kinds of language modeling methods that can be applied to the linguistic decoding part of a speech recognition system with a very large vocabulary. These models are studied experimentally on a pseudophonetic input arising from French stenotypy. The authors propose a model which combines the advantages of a statistical modeling with information theoretic tools, and those of a grammatical approach.

  17. Active cathepsins B, L, and S in murine and human pancreatitis

    PubMed Central

    Lyo, Victoria; Cattaruzza, Fiore; Kim, Tyson N.; Walker, Austin W.; Paulick, Margot; Cox, Daniel; Cloyd, Jordan; Buxbaum, James; Ostroff, James; Bogyo, Matthew; Grady, Eileen F.; Bunnett, Nigel W.

    2012-01-01

    Cathepsins regulate premature trypsinogen activation within acinar cells, a key initial step in pancreatitis. The identity, origin, and causative roles of activated cathepsins in pancreatic inflammation and pain are not defined. By using a near infrared-labeled activity-based probe (GB123) that covalently modifies active cathepsins, we localized and identified activated cathepsins in mice with cerulein-induced pancreatitis and in pancreatic juice from patients with chronic pancreatitis. We used inhibitors of activated cathepsins to define their causative role in pancreatic inflammation and pain. After GB123 administration to mice with pancreatitis, reflectance and confocal imaging showed significant accumulation of the probe in inflamed pancreas compared with controls, particularly in acinar cells and macrophages, and in spinal cord microglia and neurons. Biochemical analysis of pancreatic extracts identified them as cathepsins B, L, and S (Cat-B, Cat-L, and Cat-S, respectively). These active cathepsins were also identified in pancreatic juice from patients with chronic pancreatitis undergoing an endoscopic procedure for the treatment of pain, indicating cathepsin secretion. The cathepsin inhibitor K11777 suppressed cerulein-induced activation of Cat-B, Cat-L, and Cat-S in the pancreas and ameliorated pancreatic inflammation, nocifensive behavior, and activation of spinal nociceptive neurons. Thus pancreatitis is associated with an increase in the active forms of the proteases Cat-B, Cat-L, and Cat-S in pancreatic acinar cells and macrophages, and in spinal neurons and microglial cells. Inhibition of cathepsin activation ameliorated pancreatic inflammation and pain. Activity-based probes permit identification of proteases that are predictive biomarkers of disease progression and response to therapy and may be useful noninvasive tools for the detection of pancreatic inflammation. PMID:22899821

  18. Understanding the molecular mechanisms underlying the effects of light intensity on flavonoid production by RNA-seq analysis in Epimedium pseudowushanense B.L.Guo.

    PubMed

    Pan, Junqian; Chen, Haimei; Guo, Baolin; Liu, Chang

    2017-01-01

    Epimedium pseudowushanense B.L.Guo, a light-demanding shade herb, is used in traditional medicine to increase libido and strengthen muscles and bones. The recognition of the health benefits of Epimedium has increased its market demand. However, its resource recycling rate is low and environmentally dependent. Furthermore, its natural sources are endangered, further increasing prices. Commercial culture can address resource constraints of it.Understanding the effects of environmental factors on the production of its active components would improve the technology for cultivation and germplasm conservation. Here, we studied the effects of light intensities on the flavonoid production and revealed the molecular mechanism using RNA-seq analysis. Plants were exposed to five levels of light intensity through the periods of germination to flowering, the flavonoid contents were measured using HPLC. Quantification of epimedin A, epimedin B, epimedin C, and icariin showed that the flavonoid contents varied with different light intensity levels. And the largest amount of epimedin C was produced at light intensity level 4 (I4). Next, the leaves under the treatment of three light intensity levels ("L", "M" and "H") with the largest differences in the flavonoid content, were subjected to RNA-seq analysis. Transcriptome reconstruction identified 43,657 unigenes. All unigene sequences were annotated by searching against the Nr, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. In total, 4008, 5260, and 3591 significant differentially expressed genes (DEGs) were identified between the groups L vs. M, M vs. H and L vs. H. Particularly, twenty-one full-length genes involved in flavonoid biosynthesis were identified. The expression levels of the flavonol synthase, chalcone synthase genes were strongly associated with light-induced flavonoid abundance with the highest expression levels found in the H group. Furthermore, 65 transcription factors, including 31

  19. Gauged $B-L$ number and neutron–antineutron oscillation: long-range forces mediated by baryophotons

    DOE PAGES

    Addazi, Andrea; Berezhiani, Zurab; Kamyshkov, Yuri

    2017-05-11

    Transformation of a neutron to an antineutron n→n~ has not yet been experimentally observed. In principle, it can occur with free neutrons in the vacuum or with neutrons bound inside the nuclei. In a nuclear medium the neutron and the antineutron have different potentials and for that reason n–n~ conversion in nuclei is heavily suppressed. This transformation can also be suppressed for free neutrons in the presence of an environmental vector field that distinguishes the neutron from the antineutron. We consider the case of a gauge field coupled to the $B-L$ charge of the particles ($B-L$ photon), and we showmore » that discovery of n–n~ oscillation in experiment will lead to few order of magnitudes stronger limits on its coupling constant than present limits from the tests of the equivalence principle. If n–n~ oscillation will be discovered via nuclear instability, but not in free neutron oscillations at a corresponding level, this would indicate the presence of such environmental fifth forces. In the latter case the $B-L$ potential can be measurable by varying the external magnetic field for achieving the resonance conditions for n–n~ conversion. As for neutron–mirror neutron oscillation, such potentials should have no effect once the fifth forces are associated to a common quantum number $(B - L) - (B′ - L′)$ shared by the ordinary and mirror particles.« less

  20. The Living Dead: Transformative Experiences in Modelling Natural Selection

    ERIC Educational Resources Information Center

    Petersen, Morten Rask

    2017-01-01

    This study considers how students change their coherent conceptual understanding of natural selection through a hands-on simulation. The results show that most students change their understanding. In addition, some students also underwent a transformative experience and used their new knowledge in a leisure time activity. These transformative…

  1. Natural Beginnings: A Teacher Training Model for Early Childhood Educators.

    ERIC Educational Resources Information Center

    Wilson, Ruth A.

    This paper presents a description of Natural Beginnings, an early childhood environmental education teacher inservice workshop. The purpose, content, and format of the workshop are discussed, as are evaluation results. Evaluation results indicate that the workshop was highly effective in increasing teachers' confidence in infusing environmental…

  2. Simulation of Hydraulic and Natural Fracture Interaction Using a Coupled DFN-DEM Model

    SciTech Connect

    J. Zhou; H. Huang; M. Deo

    2016-03-01

    The presence of natural fractures will usually result in a complex fracture network due to the interactions between hydraulic and natural fracture. The reactivation of natural fractures can generally provide additional flow paths from formation to wellbore which play a crucial role in improving the hydrocarbon recovery in these ultra-low permeability reservoir. Thus, accurate description of the geometry of discrete fractures and bedding is highly desired for accurate flow and production predictions. Compared to conventional continuum models that implicitly represent the discrete feature, Discrete Fracture Network (DFN) models could realistically model the connectivity of discontinuities at both reservoir scale and well scale. In this work, a new hybrid numerical model that couples Discrete Fracture Network (DFN) and Dual-Lattice Discrete Element Method (DL-DEM) is proposed to investigate the interaction between hydraulic fracture and natural fractures. Based on the proposed model, the effects of natural fracture orientation, density and injection properties on hydraulic-natural fractures interaction are investigated.

  3. Image Discrimination Models for Object Detection in Natural Backgrounds

    NASA Technical Reports Server (NTRS)

    Ahumada, A. J., Jr.

    2000-01-01

    This paper reviews work accomplished and in progress at NASA Ames relating to visual target detection. The focus is on image discrimination models, starting with Watson's pioneering development of a simple spatial model and progressing through this model's descendents and extensions. The application of image discrimination models to target detection will be described and results reviewed for Rohaly's vehicle target data and the Search 2 data. The paper concludes with a description of work we have done to model the process by which observers learn target templates and methods for elucidating those templates.

  4. Image Discrimination Models for Object Detection in Natural Backgrounds

    NASA Technical Reports Server (NTRS)

    Ahumada, A. J., Jr.

    2000-01-01

    This paper reviews work accomplished and in progress at NASA Ames relating to visual target detection. The focus is on image discrimination models, starting with Watson's pioneering development of a simple spatial model and progressing through this model's descendents and extensions. The application of image discrimination models to target detection will be described and results reviewed for Rohaly's vehicle target data and the Search 2 data. The paper concludes with a description of work we have done to model the process by which observers learn target templates and methods for elucidating those templates.

  5. Modeling Functional Motions of Biological Systems by Customized Natural Moves.

    PubMed

    Demharter, Samuel; Knapp, Bernhard; Deane, Charlotte M; Minary, Peter

    2016-08-23

    Simulating the functional motions of biomolecular systems requires large computational resources. We introduce a computationally inexpensive protocol for the systematic testing of hypotheses regarding the dynamic behavior of proteins and nucleic acids. The protocol is based on natural move Monte Carlo, a highly efficient conformational sampling method with built-in customization capabilities that allows researchers to design and perform a large number of simulations to investigate functional motions in biological systems. We demonstrate the use of this protocol on both a protein and a DNA case study. Firstly, we investigate the plasticity of a class II major histocompatibility complex in the absence of a bound peptide. Secondly, we study the effects of the epigenetic mark 5-hydroxymethyl on cytosine on the structure of the Dickerson-Drew dodecamer. We show how our customized natural moves protocol can be used to investigate causal relationships of functional motions in biological systems.

  6. Natural Interaction Metaphors for Functional Validations of Virtual Car Models.

    PubMed

    Moehring, Mathias; Froehlich, Bernd

    2011-09-01

    Natural Interaction in virtual environments is a key requirement for the virtual validation of functional aspects in automotive product development processes. Natural Interaction is the metaphor people encounter in reality: the direct manipulation of objects by their hands. To enable this kind of Natural Interaction, we propose a pseudophysical metaphor that is both plausible enough to provide realistic interaction and robust enough to meet the needs of industrial applications. Our analysis of the most common types of objects in typical automotive scenarios guided the development of a set of refined grasping heuristics to support robust finger-based interaction of multiple hands and users. The objects' behavior in reaction to the users' finger motions is based on pseudophysical simulations, which also take various types of constrained objects into account. In dealing with real-world scenarios, we had to introduce the concept of Normal Proxies, which extend objects with appropriate normals for improved grasp detection and grasp stability. An expert review revealed that our interaction metaphors allow for an intuitive and reliable assessment of several functionalities of objects found in a car interior. Follow-up user studies showed that overall task performance and usability are similar for CAVE and HMD environments. For larger objects and more gross manipulation, using the CAVE without employing a virtual hand representation is preferred, but for more fine-grained manipulation and smaller objects, the HMD turns out to be beneficial.

  7. An Updated Natural History Model of Cervical Cancer: Derivation of Model Parameters

    PubMed Central

    Campos, Nicole G.; Burger, Emily A.; Sy, Stephen; Sharma, Monisha; Schiffman, Mark; Rodriguez, Ana Cecilia; Hildesheim, Allan; Herrero, Rolando; Kim, Jane J.

    2014-01-01

    Mathematical models of cervical cancer have been widely used to evaluate the comparative effectiveness and cost-effectiveness of preventive strategies. Major advances in the understanding of cervical carcinogenesis motivate the creation of a new disease paradigm in such models. To keep pace with the most recent evidence, we updated a previously developed microsimulation model of human papillomavirus (HPV) infection and cervical cancer to reflect 1) a shift towards health states based on HPV rather than poorly reproducible histological diagnoses and 2) HPV clearance and progression to precancer as a function of infection duration and genotype, as derived from the control arm of the Costa Rica Vaccine Trial (2004–2010). The model was calibrated leveraging empirical data from the New Mexico Surveillance, Epidemiology, and End Results Registry (1980–1999) and a state-of-the-art cervical cancer screening registry in New Mexico (2007–2009). The calibrated model had good correspondence with data on genotype- and age-specific HPV prevalence, genotype frequency in precancer and cancer, and age-specific cancer incidence. We present this model in response to a call for new natural history models of cervical cancer intended for decision analysis and economic evaluation at a time when global cervical cancer prevention policy continues to evolve and evidence of the long-term health effects of cervical interventions remains critical. PMID:25081182

  8. Widespread somatosensory sensitivity in naturally occurring canine model of osteoarthritis

    PubMed Central

    Knazovicky, David; Helgeson, Erika S.; Case, Beth; Gruen, Margaret E.; Maixner, William; Lascelles, B. Duncan X.

    2016-01-01

    Abstract Osteoarthritis (OA)-associated pain is a leading cause of disability. Central sensitization (CS), as a result of OA, is recognized as an important facet of human patients' chronic pain and has been measured in people using quantitative sensory testing (QST) testing. The spontaneous canine OA model has been suggested as a good translational model, but CS has not been explored in this model. In this study, QST was performed on dogs with and without spontaneous hip or stifle OA to determine whether OA is associated with CS in this model. Mechanical (von Frey and blunt pressure) and thermal (hot and cold) sensory thresholds obtained in dogs with chronic OA-associated pain (n = 31) were compared with those of normal dogs (n = 23). Dogs were phenotyped and joint-pain scored, and testing was performed at the OA-affected joint, cranial tibial muscle, and dorsal metatarsal region. QST summary data were evaluated using mixed-effect models to understand the influence of OA status and covariates, and dogs with OA and control dogs were compared. The presence of OA was strongly associated with hyperalgesia across all QST modalities at the index joint, cranial tibial muscle, and metatarsal site. Mechanical QST scores were significantly moderately negatively correlated with total joint-pain scores. The spontaneous canine OA model is associated with somatosensory sensitivity, likely indicative of CS. These data further validate the canine spontaneous OA model as an appropriate model of the human OA pain condition. PMID:26901805

  9. Statistical modeling of natural backgrounds in hyperspectral LWIR data

    NASA Astrophysics Data System (ADS)

    Truslow, Eric; Manolakis, Dimitris; Cooley, Thomas; Meola, Joseph

    2016-09-01

    Hyperspectral sensors operating in the long wave infrared (LWIR) have a wealth of applications including remote material identification and rare target detection. While statistical models for modeling surface reflectance in visible and near-infrared regimes have been well studied, models for the temperature and emissivity in the LWIR have not been rigorously investigated. In this paper, we investigate modeling hyperspectral LWIR data using a statistical mixture model for the emissivity and surface temperature. Statistical models for the surface parameters can be used to simulate surface radiances and at-sensor radiance which drives the variability of measured radiance and ultimately the performance of signal processing algorithms. Thus, having models that adequately capture data variation is extremely important for studying performance trades. The purpose of this paper is twofold. First, we study the validity of this model using real hyperspectral data, and compare the relative variability of hyperspectral data in the LWIR and visible and near-infrared (VNIR) regimes. Second, we illustrate how materials that are easily distinguished in the VNIR, may be difficult to separate when imaged in the LWIR.

  10. Uncertainty in natural hazards, modeling and decision support: An introduction to this volume [Chapter 1

    Treesearch

    Karin Riley; Matthew Thompson; Peter Webley; Kevin D. Hyde

    2017-01-01

    Modeling has been used to characterize and map natural hazards and hazard susceptibility for decades. Uncertainties are pervasive in natural hazards analysis, including a limited ability to predict where and when extreme events will occur, with what consequences, and driven by what contributing factors. Modeling efforts are challenged by the intrinsic...

  11. A survival model for individual shortleaf pine trees in even-aged natural stands

    Treesearch

    Thomas B. Lynch; Michael M. Huebschmann; Paul A. Murphy

    2000-01-01

    A model was developed that predicts the probability of survival for individual shortleaf pine (Pinus echinata Mill.) trees growing in even-aged natural stands. Data for model development were obtained from the first two measurements of permanently established plots located in naturally occurring shortleaf pine forests on the Ouachita and...

  12. A survival model for individual shortleaf pine trees in even-aged natural stands

    Treesearch

    Thomas B. Lynch; Michael M. Huebschmann; Paul A. Murphy

    2000-01-01

    A model was developed that predicts the probability of survival for individual shortleaf pine (Pinus echinata Mill.) trees growing in even-aged natural stands. Data for model development were obtained from the first two measurements of permanently established plots located in naturally occurring shortleaf pine forests on the Ouachita and Ozark...

  13. Modelling methane emissions from natural wetlands by development and application of the TRIPLEX-GHG model

    USGS Publications Warehouse

    Zhu, Qing; Liu, Jinxun; Peng, C.; Chen, H.; Fang, X.; Jiang, H.; Yang, G.; Zhu, D.; Wang, W.; Zhou, X.

    2014-01-01

    A new process-based model TRIPLEX-GHG was developed based on the Integrated Biosphere Simulator (IBIS), coupled with a new methane (CH4) biogeochemistry module (incorporating CH4 production, oxidation, and transportation processes) and a water table module to investigate CH4 emission processes and dynamics that occur in natural wetlands. Sensitivity analysis indicates that the most sensitive parameters to evaluate CH4 emission processes from wetlands are r (defined as the CH4 to CO2 release ratio) and Q10 in the CH4 production process. These two parameters were subsequently calibrated to data obtained from 19 sites collected from approximately 35 studies across different wetlands globally. Being heterogeneously spatially distributed, r ranged from 0.1 to 0.7 with a mean value of 0.23, and the Q10 for CH4 production ranged from 1.6 to 4.5 with a mean value of 2.48. The model performed well when simulating magnitude and capturing temporal patterns in CH4 emissions from natural wetlands. Results suggest that the model is able to be applied to different wetlands under varying conditions and is also applicable for global-scale simulations.

  14. A flexible, parallel model of natural language generation

    SciTech Connect

    Ward, N.

    1991-01-01

    This paper describes a structured connectionist system for natural language generation. FIG, short for Flexible Incremental Generator, is based on a single network which encodes lexical knowledge, syntactic knowledge, and world knowledge. In the initial state, some nodes representing concepts are sources of activation: this represents the input. Activation flows from these nodes to nodes representing words via the various knowledge structures of the network. When the network settles, the most high activated word is selected and emitted, activation levels are updated to represent the current state. This process of settle, emit, and update repeats until all of the input has been conveyed. An utterance is simply the result of successive word choices.

  15. Mathematic modeling of complex aquifer: Evian Natural Mineral Water case study considering lumped and distributed models.

    NASA Astrophysics Data System (ADS)

    Henriot, abel; Blavoux, bernard; Travi, yves; Lachassagne, patrick; Beon, olivier; Dewandel, benoit; Ladouche, bernard

    2013-04-01

    The Evian Natural Mineral Water (NMW) aquifer is a highly heterogeneous Quaternary glacial deposits complex composed of three main units, from bottom to top: - The "Inferior Complex" mainly composed of basal and impermeable till lying on the Alpine rocks. It outcrops only at the higher altitudes but is known in depth through drilled holes. - The "Gavot Plateau Complex" is an interstratified complex of mainly basal and lateral till up to 400 m thick. It outcrops at heights above approximately 850 m a.m.s.l. and up to 1200 m a.m.s.l. over a 30 km² area. It is the main recharge area known for the hydromineral system. - The "Terminal Complex" from which the Evian NMW is emerging at 410 m a.m.s.l. It is composed of sand and gravel Kame terraces that allow water to flow from the deep "Gavot Plateau Complex" permeable layers to the "Terminal Complex". A thick and impermeable terminal till caps and seals the system. Aquifer is then confined at its downstream area. Because of heterogeneity and complexity of this hydrosystem, distributed modeling tools are difficult to implement at the whole system scale: important hypothesis would have to be made about geometry, hydraulic properties, boundary conditions for example and extrapolation would lead with no doubt to unacceptable errors. Consequently a modeling strategy is being developed and leads also to improve the conceptual model of the hydrosystem. Lumped models mainly based on tritium time series allow the whole hydrosystem to be modeled combining in series: an exponential model (superficial aquifers of the "Gavot Plateau Complex"), a dispersive model (Gavot Plateau interstratified complex) and a piston flow model (sand and gravel from the Kame terraces) respectively 8, 60 and 2.5 years of mean transit time. These models provide insight on the governing parameters for the whole mineral aquifer. They help improving the current conceptual model and are to be improved with other environmental tracers such as CFC, SF6. A

  16. A search for B-L R-parity-violating top squark decays in √{ s} = 13 TeV pp collisions with the ATLAS detector

    NASA Astrophysics Data System (ADS)

    Dyckes, Ian; Atlas Experiment Collaboration

    2017-01-01

    A search for pair produced massive particles decaying to b-quarks plus leptons is presented using the √{ s} = 13 TeV proton-proton collision data collected with the ATLAS detector at the LHC in 2016. This search is motivated by a B-L extension to the MSSM, in which the scalar partner of the top quark (the stop) may be the Lightest Supersymmetric Particle (the LSP). In this model, the stop predominantly decays via an R-Parity violating coupling to a b-quark plus a lepton. This model is targeted by searching for an excess in final states containing b-tagged jets and two light leptons (electrons or muons).

  17. Potential model for single-sided naturally ventilated buildings in China

    SciTech Connect

    Wei, Yin; Guo-qiang, Zhang; Jing, Liu; San-xian, Xia; Xiao, Wang

    2010-09-15

    The paper investigates a single-sided naturally ventilated buildings potential model considering number of factors in China. This model can be used to estimate potential of natural ventilation via local climate data and building parameters. The main goal of the model is to predict natural ventilation hours and hourly ventilation flow rate. In fluid model, formula of single-sided natural ventilation by coupling wind pressure and temperature difference was used to calculate air flow rate. Accordingly, the paper analyzed four typical cities in different climate region in China and calculated pressure difference Pascal hours (PDPH). The results show that single-sided ventilation has fewer adaptive comfort hours than two-sided ventilation and much less ventilation volume. This model provided quantitative information for early stage architectural natural ventilation design and building energy efficiency evaluation. (author)

  18. Biomimetics - using nature as an inspiring model for innovation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2006-01-01

    In this presentation, various aspects of the field of biomimetics will be reviewed, examples of inspiring biological models and practical applications will be described, and challenges and potential direction of the field will be discussed.

  19. Biomimetics - using nature as an inspiring model for innovation

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    2006-01-01

    In this presentation, various aspects of the field of biomimetics will be reviewed, examples of inspiring biological models and practical applications will be described, and challenges and potential direction of the field will be discussed.

  20. Natural vs. artificial groundwater recharge, quantification through inverse modeling

    NASA Astrophysics Data System (ADS)

    Hashemi, H.; Berndtsson, R.; Kompani-Zare, M.; Persson, M.

    2013-02-01

    Estimating the change in groundwater recharge from an introduced artificial recharge system is important in order to evaluate future water availability. This paper presents an inverse modeling approach to quantify the recharge contribution from both an ephemeral river channel and an introduced artificial recharge system based on floodwater spreading in arid Iran. The study used the MODFLOW-2000 to estimate recharge for both steady- and unsteady-state conditions. The model was calibrated and verified based on the observed hydraulic head in observation wells and model precision, uncertainty, and model sensitivity were analyzed in all modeling steps. The results showed that in a normal year without extreme events, the floodwater spreading system is the main contributor to recharge with 80% and the ephemeral river channel with 20% of total recharge in the studied area. Uncertainty analysis revealed that the river channel recharge estimation represents relatively more uncertainty in comparison to the artificial recharge zones. The model is also less sensitive to the river channel. The results show that by expanding the artificial recharge system, the recharge volume can be increased even for small flood events, while the recharge through the river channel increases only for major flood events.

  1. Natural vs. artificial groundwater recharge, quantification through inverse modeling

    NASA Astrophysics Data System (ADS)

    Hashemi, H.; Berndtsson, R.; Kompani-Zare, M.; Persson, M.

    2012-08-01

    Estimating the change in groundwater recharge from an introduced artificial recharge system is important in order to evaluate future water availability. This paper presents an inverse modeling approach to quantify the recharge contribution from both an ephemeral river channel and an introduced artificial recharge system based on floodwater spreading in arid Iran. The study used the MODFLOW-2000 to estimate recharge for both steady and unsteady-state conditions. The model was calibrated and verified based on the observed hydraulic head in observation wells and model precision, uncertainty, and model sensitivity were analyzed in all modeling steps. The results showed that in a normal year without extreme events the floodwater spreading system is the main contributor to recharge with 80% and the ephemeral river channel with 20% of total recharge in the studied area. Uncertainty analysis revealed that the river channel recharge estimation represents relatively more uncertainty in comparison to the artificial recharge zones. The model is also less sensitive to the river channel. The results show that by expanding the artificial recharge system the recharge volume can be increased even for small flood events while the recharge through the river channel increases only for major flood events.

  2. Stochastic Model for the Vocabulary Growth in Natural Languages

    NASA Astrophysics Data System (ADS)

    Gerlach, Martin; Altmann, Eduardo G.

    2013-04-01

    We propose a stochastic model for the number of different words in a given database which incorporates the dependence on the database size and historical changes. The main feature of our model is the existence of two different classes of words: (i) a finite number of core words, which have higher frequency and do not affect the probability of a new word to be used, and (ii) the remaining virtually infinite number of noncore words, which have lower frequency and, once used, reduce the probability of a new word to be used in the future. Our model relies on a careful analysis of the Google Ngram database of books published in the last centuries, and its main consequence is the generalization of Zipf’s and Heaps’ law to two-scaling regimes. We confirm that these generalizations yield the best simple description of the data among generic descriptive models and that the two free parameters depend only on the language but not on the database. From the point of view of our model, the main change on historical time scales is the composition of the specific words included in the finite list of core words, which we observe to decay exponentially in time with a rate of approximately 30 words per year for English.

  3. Diffraction studies on natural and model lipid bilayers

    NASA Astrophysics Data System (ADS)

    Sebastiani, F.; Harvey, R.; Khanniche, S.; Artero, J.-B.; Haertlein, M.; Fragneto, G.

    2012-11-01

    In this study we have used neutron diffraction to examine the swelling behaviour and bilayer parameters of membranes reconstituted from polar lipids extracted from B. subtilis and model systems composed of synthetic phospholipids. Evidence for phase separation in the model system (lacking in Lysyl-PG, L-PG) is discussed in relation to its possible contribution to membrane domain formation through lipid-lipid interactions. Comparing these results with those obtained from the bilayers composed of lipids extracted from bacterial cells gives us some indication of the role of L-PG in the B. subtilis plasma membrane.

  4. Developing Models to Forcast Sales of Natural Christmas Trees

    Treesearch

    Lawrence D. Garrett; Thomas H. Pendleton

    1977-01-01

    A study of practices for marketing Christmas trees in Winston-Salem, North Carolina, and Denver, Colorado, revealed that such factors as retail lot competition, tree price, consumer traffic, and consumer income were very important in determining a particular retailer's sales. Analyses of 4 years of market data were used in developing regression models for...

  5. Capturing and Modeling Domain Knowledge Using Natural Language Processing Techniques

    DTIC Science & Technology

    2005-06-01

    ONTOLOGY ENGINEERING METHODOLOGIES Most of published ontology engineering methods require (SMEs) to elicit knowledge objects of a domain. In all...Gilles Nathalie, Biébow Brigitte Szulman Sylvie. "Revisiting Ontology Design: A Method Based on Corpus Analysis”, Knowledge Engineering and Knowledge ...from Text”, Knowledge Engineering and Knowledge Management. Methods , Models and Tools. Rose Dieng and Olivier Corby (Eds.) 12th International

  6. Diagnosing Students' Understanding of the Nature of Models

    ERIC Educational Resources Information Center

    Gogolin, Sarah; Krüger, Dirk

    2017-01-01

    Students' understanding of models in science has been subject to a number of investigations. The instruments the researchers used are suitable for educational research but, due to their complexity, cannot be employed directly by teachers. This article presents forced choice (FC) tasks, which, assembled as a diagnostic instrument, are supposed to…

  7. Tribology studies of the natural knee using an animal model in a new whole joint natural knee simulator.

    PubMed

    Liu, Aiqin; Jennings, Louise M; Ingham, Eileen; Fisher, John

    2015-09-18

    The successful development of early-stage cartilage and meniscus repair interventions in the knee requires biomechanical and biotribological understanding of the design of the therapeutic interventions and their tribological function in the natural joint. The aim of this study was to develop and validate a porcine knee model using a whole joint knee simulator for investigation of the tribological function and biomechanical properties of the natural knee, which could then be used to pre-clinically assess the tribological performance of cartilage and meniscal repair interventions prior to in vivo studies. The tribological performance of standard artificial bearings in terms of anterior-posterior (A/P) shear force was determined in a newly developed six degrees of freedom tribological joint simulator. The porcine knee model was then developed and the tribological properties in terms of shear force measurements were determined for the first time for three levels of biomechanical constraints including A/P constrained, spring force semi-constrained and A/P unconstrained conditions. The shear force measurements showed higher values under the A/P constrained condition (predominantly sliding motion) compared to the A/P unconstrained condition (predominantly rolling motion). This indicated that the shear force simulation model was able to differentiate between tribological behaviours when the femoral and tibial bearing was constrained to slide or/and roll. Therefore, this porcine knee model showed the potential capability to investigate the effect of knee structural, biomechanical and kinematic changes, as well as different cartilage substitution therapies on the tribological function of natural knee joints.

  8. Improvement of Endurance of DMD Animal Model Using Natural Polyphenols

    PubMed Central

    Sitzia, Clementina; Farini, Andrea; Fortunato, Francesco; Razini, Paola; Erratico, Silvia; Tavelli, Alessandro; Fabrizi, Francesco; Belicchi, Marzia; Torrente, Yvan

    2015-01-01

    Duchenne muscular dystrophy (DMD), the most common form of muscular dystrophy, is characterized by muscular wasting caused by dystrophin deficiency that ultimately ends in force reduction and premature death. In addition to primary genetic defect, several mechanisms contribute to DMD pathogenesis. Recently, antioxidant supplementation was shown to be effective in the treatment of multiple diseases including muscular dystrophy. Different mechanisms were hypothesized such as reduced hydroxyl radicals, nuclear factor-κB deactivation, and NO protection from inactivation. Following these promising evidences, we investigated the effect of the administration of a mix of dietary natural polyphenols (ProAbe) on dystrophic mdx mice in terms of muscular architecture and functionality. We observed a reduction of muscle fibrosis deposition and myofiber necrosis together with an amelioration of vascularization. More importantly, the recovery of the morphological features of dystrophic muscle leads to an improvement of the endurance of treated dystrophic mice. Our data confirmed that ProAbe-based diet may represent a strategy to coadjuvate the treatment of DMD. PMID:25861640

  9. MSW to synthetic natural gas: System modeling and thermodynamics assessment.

    PubMed

    Zhu, Lin; Zhang, Le; Fan, Junming; Jiang, Peng; Li, Luling

    2016-02-01

    To achieve environmental-friendly and energy-efficiency synthetic natural gas (SNG) production routing from municipal solid waste (MSW), a MSW-to-SNG process is unprecedentedly presented in this work, of which the designed configuration is developed and simulated with the aid of Aspen Plus. In addition, sensitivity analyses on major operation parameters, such as equivalence volume ratio (ER), steam-to-MSW mass ratio (S/M) and methanation pressure, are performed with the discussion of process efficiencies and SNG quality. In parallel, the comparison analysis is considered by adopting various MSW material. In this work, the composition of SNG mainly consists of 87.7% CH4, 2.9% CO2, 2.3% H2 and 7.1% N2. And lower heating value (LHV) together with Wobbe index of SNG are separately 31.66MJ/Nm(3) and 45.90MJ/Nm(3). Moreover, the wood-to-SNG, MSW-to-SNG and coal-to-SNG processes are carried out to demonstrate the superiority of the MSW-to-SNG process. The results reveal that the MSW-to-SNG process is a promising option to dispose MSW environmentally, meanwhile converting MSW to the valuable SNG.

  10. The horse as a model of naturally occurring osteoarthritis

    PubMed Central

    McIlwraith, C. W.; Frisbie, D. D.; Kawcak, C. E.

    2012-01-01

    Osteoarthritis (OA) is an important cause of pain, disability and economic loss in humans, and is similarly important in the horse. Recent knowledge on post-traumatic OA has suggested opportunities for early intervention, but it is difficult to identify the appropriate time of these interventions. The horse provides two useful mechanisms to answer these questions: 1) extensive experience with clinical OA in horses; and 2) use of a consistently predictable model of OA that can help study early pathobiological events, define targets for therapeutic intervention and then test these putative therapies. This paper summarises the syndromes of clinical OA in horses including pathogenesis, diagnosis and treatment, and details controlled studies of various treatment options using an equine model of clinical OA. PMID:23610661

  11. A Theoretical Model for the Associative Nature of Conference Participation

    PubMed Central

    Smiljanić, Jelena; Chatterjee, Arnab; Kauppinen, Tomi; Mitrović Dankulov, Marija

    2016-01-01

    Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and broadening of scientists’ collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientist’s association with the community. Here we discuss and formulate the problem of discovering how a scientist’s previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists’ participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the community. An active participation in a conference series strengthens the scientist’s association with that particular conference community and thus increases the probability of future participations. PMID:26859404

  12. A Theoretical Model for the Associative Nature of Conference Participation.

    PubMed

    Smiljanić, Jelena; Chatterjee, Arnab; Kauppinen, Tomi; Mitrović Dankulov, Marija

    2016-01-01

    Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and broadening of scientists' collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientist's association with the community. Here we discuss and formulate the problem of discovering how a scientist's previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists' participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the community. An active participation in a conference series strengthens the scientist's association with that particular conference community and thus increases the probability of future participations.

  13. Thermal modeling of phase change solidification in thermal control devices including natural convection effects

    NASA Technical Reports Server (NTRS)

    Ukanwa, A. O.; Stermole, F. J.; Golden, J. O.

    1972-01-01

    Natural convection effects in phase change thermal control devices were studied. A mathematical model was developed to evaluate natural convection effects in a phase change test cell undergoing solidification. Although natural convection effects are minimized in flight spacecraft, all phase change devices are ground tested. The mathematical approach to the problem was to first develop a transient two-dimensional conduction heat transfer model for the solidification of a normal paraffin of finite geometry. Next, a transient two-dimensional model was developed for the solidification of the same paraffin by a combined conduction-natural-convection heat transfer model. Throughout the study, n-hexadecane (n-C16H34) was used as the phase-change material in both the theoretical and the experimental work. The models were based on the transient two-dimensional finite difference solutions of the energy, continuity, and momentum equations.

  14. Nonlinear natural engine: Model for thermodynamic processes in mesoscale systems

    PubMed Central

    Wheatley, John; Buchanan, D. S.; Swift, G. W.; Migliori, A.; Hofler, T.

    1985-01-01

    To develop intuition on the possible application of concepts from thermodynamic heat engines to mesoscale systems, we have constructed and studied a model thermoacoustic heat engine. The model consists of a chain of coupled nonlinear acoustic vibrators in which the primary thermodynamic medium is argon gas, the secondary thermodynamic medium is constituted by solids bounding the gas, and frequencies are ca. 3 × 102 Hz. The nonlinear elements are the necks, made flexible by means of an oil-loaded DuPont Kapton film, of Helmholtz resonators. When the primary medium is driven uniformly by an acoustic driver at a frequency somewhat below the low-amplitude resonant frequency and at a high enough driving amplitude, stationary localized or solitary states appear irreversibly on the chain. These are characterized by a higher vibrational amplitude than that in surrounding vibrators, where the amplitude can decrease; by the appearance of deep subharmonics of the drive frequency, corresponding to driven low-frequency vibrations of the Kapton film-oil systems; and by the pumping of heat toward the localized states. Possible implications of these results for mesoscale systems consisting of chains of molecular vibrators are then discussed. Images PMID:16593625

  15. Nonlinear natural engine: model for thermodynamic processes in mesoscale systems

    SciTech Connect

    Wheatley, J.; Buchanan, D.S.; Swift, G.W.; Migliori, A.; Hofler, T.

    1985-12-01

    To develop intuition on the possible application of concepts from thermodynamic heat engines to mesoscale systems, the authors have constructed and studied a model thermoacoustic heat engine. The model consists of a chain of coupled nonlinear acoustic vibrators in which the primary thermodynamic medium is argon gas, the secondary thermodynamic medium is constituted by solids bounding the gas, and frequencies are ca. 3 x 10/sup 2/ Hz. The nonlinear elements are the necks, made flexible by means of an oil-loaded DuPont Kapton film, of Helmholtz resonators. When the primary medium is driven uniformly by an acoustic driver at a frequency somewhat below the low-amplitude resonant frequency and at a high enough driving amplitude, stationary localized or solitary states appear irreversibly on the chain. These are characterized by a higher vibrational amplitude than that in surrounding vibrators, where the amplitude can decrease; by the appearance of deep subharmonics of the drive frequency, corresponding to driven low-frequency vibrations of the Kapton film-oil systems; and by the pumping of heat toward the localized states. Possible implications of these results for mesoscale systems consisting of chains of molecular vibrators are then discussed. 19 references, 3 figures.

  16. Nonlinear natural engine: Model for thermodynamic processes in mesoscale systems.

    PubMed

    Wheatley, J; Buchanan, D S; Swift, G W; Migliori, A; Hofler, T

    1985-12-01

    To develop intuition on the possible application of concepts from thermodynamic heat engines to mesoscale systems, we have constructed and studied a model thermoacoustic heat engine. The model consists of a chain of coupled nonlinear acoustic vibrators in which the primary thermodynamic medium is argon gas, the secondary thermodynamic medium is constituted by solids bounding the gas, and frequencies are ca. 3 x 10(2) Hz. The nonlinear elements are the necks, made flexible by means of an oil-loaded DuPont Kapton film, of Helmholtz resonators. When the primary medium is driven uniformly by an acoustic driver at a frequency somewhat below the low-amplitude resonant frequency and at a high enough driving amplitude, stationary localized or solitary states appear irreversibly on the chain. These are characterized by a higher vibrational amplitude than that in surrounding vibrators, where the amplitude can decrease; by the appearance of deep subharmonics of the drive frequency, corresponding to driven low-frequency vibrations of the Kapton film-oil systems; and by the pumping of heat toward the localized states. Possible implications of these results for mesoscale systems consisting of chains of molecular vibrators are then discussed.

  17. Naturally light Dirac neutrino in Left-Right Symmetric Model

    NASA Astrophysics Data System (ADS)

    Borah, Debasish; Dasgupta, Arnab

    2017-06-01

    We study the possibility of generating tiny Dirac masses of neutrinos in Left-Right Symmetric Model (LRSM) without requiring the existence of any additional symmetries. The charged fermions acquire masses through a universal seesaw mechanism due to the presence of additional vector like fermions. The neutrinos acquire a one-loop Dirac mass from the same additional vector like charged leptons without requiring any additional discrete symmetries. The model can also be extended by an additional Z2 symmetry in order to have a scotogenic version of this scenario predicting a stable dark matter candidate. We show that the latest Planck upper bound on the effective number of relativistic degrees of freedom Neff=3.15 ± 0.23 tightly constrains the right sector gauge boson masses to be heavier than 3.548 TeV . This bound on gauge boson mass also affects the allowed values of right scalar doublet dark matter mass from the requirement of satisfying the Planck bound on dark matter relic abundance. We also discuss the possible implications of such a scenario in charged lepton flavour violation and generating observable electric dipole moment of leptons.

  18. Nature, theory and modelling of geophysical convective planetary boundary layers

    NASA Astrophysics Data System (ADS)

    Zilitinkevich, Sergej

    2015-04-01

    Geophysical convective planetary boundary layers (CPBLs) are still poorly reproduced in oceanographic, hydrological and meteorological models. Besides the mean flow and usual shear-generated turbulence, CPBLs involve two types of motion disregarded in conventional theories: 'anarchy turbulence' comprised of the buoyancy-driven plumes, merging to form larger plumes instead of breaking down, as postulated in conventional theory (Zilitinkevich, 1973), large-scale organised structures fed by the potential energy of unstable stratification through inverse energy transfer in convective turbulence (and performing non-local transports irrespective of mean gradients of transporting properties). C-PBLs are strongly mixed and go on growing as long as the boundary layer remains unstable. Penetration of the mixed layer into the weakly turbulent, stably stratified free flow causes turbulent transports through the CPBL outer boundary. The proposed theory, taking into account the above listed features of CPBL, is based on the following recent developments: prognostic CPBL-depth equation in combination with diagnostic algorithm for turbulence fluxes at the CPBL inner and outer boundaries (Zilitinkevich, 1991, 2012, 2013; Zilitinkevich et al., 2006, 2012), deterministic model of self-organised convective structures combined with statistical turbulence-closure model of turbulence in the CPBL core (Zilitinkevich, 2013). It is demonstrated that the overall vertical transports are performed mostly by turbulence in the surface layer and entrainment layer (at the CPBL inner and outer boundaries) and mostly by organised structures in the CPBL core (Hellsten and Zilitinkevich, 2013). Principal difference between structural and turbulent mixing plays an important role in a number of practical problems: transport and dispersion of admixtures, microphysics of fogs and clouds, etc. The surface-layer turbulence in atmospheric and marine CPBLs is strongly enhanced by the velocity shears in

  19. Short-Term Energy Outlook Model Documentation: Natural Gas Consumption and Prices

    EIA Publications

    2015-01-01

    The natural gas consumption and price modules of the Short-Term Energy Outlook (STEO) model are designed to provide consumption and end-use retail price forecasts for the residential, commercial, and industrial sectors in the nine Census districts and natural gas working inventories in three regions. Natural gas consumption shares and prices in each Census district are used to calculate an average U.S. retail price for each end-use sector.

  20. Short-Term Energy Outlook Model Documentation: Natural Gas Consumption and Prices

    EIA Publications

    2015-01-01

    The natural gas consumption and price modules of the Short-Term Energy Outlook (STEO) model are designed to provide consumption and end-use retail price forecasts for the residential, commercial, and industrial sectors in the nine Census districts and natural gas working inventories in three regions. Natural gas consumption shares and prices in each Census district are used to calculate an average U.S. retail price for each end-use sector.

  1. A GIS-based Model for Natural Gas Data Conversion

    NASA Astrophysics Data System (ADS)

    Bitik, E.; Seker, D. Z.; Denli, H. H.

    2014-12-01

    In Turkey gas utility sector has undergone major changes in terms of increased competition between gas providers, efforts in improving services, and applying new technological solutions. This paper discusses the challenges met by gas companies to switch from long workflows of gas distribution, sales and maintenance into IT driven efficient management of complex information both spatially and non-spatially. The aim of this study is migration of all gas data and information into a GIS environment in order to manage and operate all infrastructure investments with a Utility Management System. All data conversion model for migration was designed and tested during the study. A flowchart is formed to transfer the old data layers to the new structure based on geodatabase.

  2. GADB: A database facility for modelling naturally occurring geophysical fields

    NASA Technical Reports Server (NTRS)

    Dampney, C. N. G.

    1983-01-01

    In certain kinds of geophysical surveys, the fields are continua, but measured at discrete points referenced by their position or time of measurement. Systems of this kind are better modelled by databases built from basic data structures attuned to representing traverses across continua that are not of pre-defined fixed length. The general Array DataBase is built on arrays (ordered sequencies of data) with each array holding data elements of one type. The arrays each occupy their own physical data set, in turn inter-related by a hierarchy to other arrays over the same space/time reference points. The GADB illustrates the principle that a data facility should reflect the fundamental properties of its data, and support retrieval based on the application's view. The GADB is being tested by its use in NASA's project MAGSAT.

  3. Teaching Concepts of Natural Sciences to Foreigners through Content-Based Instruction: The Adjunct Model

    ERIC Educational Resources Information Center

    Satilmis, Yilmaz; Yakup, Doganay; Selim, Guvercin; Aybarsha, Islam

    2015-01-01

    This study investigates three models of content-based instruction in teaching concepts and terms of natural sciences in order to increase the efficiency of teaching these kinds of concepts in realization and to prove that the content-based instruction is a teaching strategy that helps students understand concepts of natural sciences. Content-based…

  4. Natural variability of the climate as predicted by a simple ocean model with parameterized thermohaline circulation

    SciTech Connect

    Watts, R.G.; Li, S.

    1995-12-31

    Variability of the Earth`s climate can take place on many time scales as a result of internal features. This natural variability is important to humans since it affects such important human enterprises as agriculture, floods, droughts, etc. The authors investigate natural variability within a simple ocean model.

  5. The Communication Model and the Nature of Change in Terms of Deforestation in China since 1949

    ERIC Educational Resources Information Center

    Tian, Dexin; Chao, Chin-Chung

    2010-01-01

    This article explores the communication model and nature of change in terms of deforestation in China since 1949. Through Lasswell's communication model and the theory of change and via historical analysis and extended literature review, we have discovered: First, Mao's government adopted an effective one-way top-down communication model with…

  6. Some insights in novel risk modeling of liquefied natural gas carrier maintenance operations

    NASA Astrophysics Data System (ADS)

    Nwaoha, T. C.; John, Andrew

    2016-06-01

    This study discusses the analysis of various modeling approaches and maintenance techniques applicable to the Liquefied Natural Gas (LNG) carrier operations in the maritime environment. Various novel modeling techniques are discussed; including genetic algorithms, fuzzy logic and evidential reasoning. We also identify the usefulness of these algorithms in the LNG carrier industry in the areas of risk assessment and maintenance modeling.

  7. The Communication Model and the Nature of Change in Terms of Deforestation in China since 1949

    ERIC Educational Resources Information Center

    Tian, Dexin; Chao, Chin-Chung

    2010-01-01

    This article explores the communication model and nature of change in terms of deforestation in China since 1949. Through Lasswell's communication model and the theory of change and via historical analysis and extended literature review, we have discovered: First, Mao's government adopted an effective one-way top-down communication model with…

  8. The rabbit pup, a natural model of nursing anticipatory activity

    PubMed Central

    Caba, Mario; González-Mariscal, Gabriela

    2009-01-01

    Mother rabbits nurse their young once a day with circadian periodicity. Nursing bouts are brief (ca. 3 min) and occur inside the maternal burrow. Despite this limited contact mother rabbits and their pups are tuned to each other to ensure that the capacities of each party are used efficiently to ensure the weaning of a healthy litter. In this review we present behavioral, hormonal, metabolic and hormonal correlates of this phenomenon in mother rabbits and their pups. Research is revealing that the circadian rhythm of locomotion shifts in parallel to the timing of nursing in both parties. In pups corticosterone has a circadian rhythm with highest levels at the time of nursing. Other metabolic and hormonal parameters follow an exogenous or endogenous rhythm which is affected by the time of nursing. In the brain clock genes (e.g., Per1) are differentially expressed in specific brain regions (e.g., suprachiasmatic nucleus, paraventricular nucleus) in relation to providing or ingesting milk in mothers and young, respectively. These findings suggest that circadian activities are modulated, in the mothers, by suckling stimulation and, in the young, by the ingestion of milk and/or the perception of the mammary pheromone. In conclusion the rabbit pup is an extraordinary model for studying the entraining by a single daily food pulse with minimal manipulations. The mother offers the possibility of studying nursing as a non-photic synchronizer, also with minimal manipulation, as suckling stimulation from the litter occurs only once daily PMID:19863657

  9. Naturalism and the social model of disability: allied or antithetical?

    PubMed

    Sisti, Dominic A

    2015-07-01

    The question of how disability should be defined is fraught with political, ethical and philosophical complexities. The social model of disability, which posits that disability is socially and politically constructed and is characterised by systemic barriers, has enjoyed broad acceptance that is exemplified by the slow but steady progress in securing civil rights for persons with disabilities. Yet, there remains a palpable tension between disability studies scholars and activists and bioethicists. While philosophers and bioethicists should heed the theories developed from the standpoint of persons with disabilities, disability activists should acknowledge the possibility that philosophical theories about the basic reality of disease, illness, health, function and impairment offer a more steady foundation for social or political critiques of disability. I argue that naturalistic theories of function and dysfunction provide a valuable starting point to clarify questions about the broader concept of disability. A naturalist theory of function may serve as the core of the concept of disability and provide disability scholars and bioethicists alike a stronger set of arguments in analysing real or potential instances of disability. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  10. Naturalism and the social model of disability: allied or antithetical?

    PubMed Central

    Sisti, Dominic A

    2015-01-01

    The question of how disability should be defined is fraught with political, ethical and philosophical complexities. The social model of disability, which posits that disability is socially and politically constructed and is characterised by systemic barriers, has enjoyed broad acceptance that is exemplified by the slow but steady progress in securing civil rights for persons with disabilities. Yet, there remains a palpable tension between disability studies scholars and activists and bioethicists. While philosophers and bioethicists should heed the theories developed from the standpoint of persons with disabilities, disability activists should acknowledge the possibility that philosophical theories about the basic reality of disease, illness, health, function and impairment offer a more steady foundation for social or political critiques of disability. I argue that naturalistic theories of function and dysfunction provide a valuable starting point to clarify questions about the broader concept of disability. A naturalist theory of function may serve as the core of the concept of disability and provide disability scholars and bioethicists alike a stronger set of arguments in analysing real or potential instances of disability. PMID:25341736

  11. Far-field contractional polarity changes in models and nature

    NASA Astrophysics Data System (ADS)

    Munteanu, Ioan; Willingshofer, Ernst; Matenco, Liviu; Sokoutis, Dimitrios; Cloetingh, Sierd

    2014-06-01

    A change in contractional polarity occurs when the direction of tectonic transport switches along strike. This switch is conditioned by lateral variations in rheology or inherited asymmetries, such as contrasts in structure or changes in the polarity of subduction zones. The parameters controlling contractional polarity changes are less understood in situations when the strain is transferred at large distances from indenters. Analysing this type of strain transfer is critical for understanding the mechanics of thrusting in fore- or back-arc settings of orogenic areas. Comparison of crustal-scale analogue modelling with the inversion of the Black Sea back-arc and the formation of the New Guinea-New Britain fore-arc suggest that far-field changes in contractional polarity are related to rheological contrasts across inherited normal faults. The initial extension creates rheological weak zones that localize the subsequent far-field contractional deformation along groups of thrusts with opposite vergence along the strike of the system. The largest amount of far-field contractional deformation is recorded in the transfer zone located between the two indenters moving in opposite directions and is particularly high when inverting oblique extensional systems.

  12. Representing natural and manmade drainage systems in an earth system modeling framework

    SciTech Connect

    Li, Hongyi; Wu, Huan; Huang, Maoyi; Leung, Lai-Yung R.

    2012-08-27

    Drainage systems can be categorized into natural or geomorphological drainage systems, agricultural drainage systems and urban drainage systems. They interact closely among themselves and with climate and human society, particularly under extreme climate and hydrological events such as floods. This editorial articulates the need to holistically understand and model drainage systems in the context of climate change and human influence, and discusses the requirements and examples of feasible approaches to representing natural and manmade drainage systems in an earth system modeling framework.

  13. Natural Decompositions of Perceived Transparency: Reply to Albert (2008)

    ERIC Educational Resources Information Center

    Anderson, Barton L.; Singh, Manish; O'Vari, Judit

    2008-01-01

    In M. Singh and B. L. Anderson, the authors proposed a model based on ratios of Michelson contrasts to explain how human observers quantitatively scale the perceived opacity of transparent surfaces. In subsequent work by B. L. Anderson, M. Singh, & J. Meng, the authors found that this model failed to generalize to other contexts and replaced it…

  14. Natural Decompositions of Perceived Transparency: Reply to Albert (2008)

    ERIC Educational Resources Information Center

    Anderson, Barton L.; Singh, Manish; O'Vari, Judit

    2008-01-01

    In M. Singh and B. L. Anderson, the authors proposed a model based on ratios of Michelson contrasts to explain how human observers quantitatively scale the perceived opacity of transparent surfaces. In subsequent work by B. L. Anderson, M. Singh, & J. Meng, the authors found that this model failed to generalize to other contexts and replaced it…

  15. Integrating human and natural systems in community psychology: an ecological model of stewardship behavior.

    PubMed

    Moskell, Christine; Allred, Shorna Broussard

    2013-03-01

    Community psychology (CP) research on the natural environment lacks a theoretical framework for analyzing the complex relationship between human systems and the natural world. We introduce other academic fields concerned with the interactions between humans and the natural environment, including environmental sociology and coupled human and natural systems. To demonstrate how the natural environment can be included within CP's ecological framework, we propose an ecological model of urban forest stewardship action. Although ecological models of behavior in CP have previously modeled health behaviors, we argue that these frameworks are also applicable to actions that positively influence the natural environment. We chose the environmental action of urban forest stewardship because cities across the United States are planting millions of trees and increased citizen participation in urban tree planting and stewardship will be needed to sustain the benefits provided by urban trees. We used the framework of an ecological model of behavior to illustrate multiple levels of factors that may promote or hinder involvement in urban forest stewardship actions. The implications of our model for the development of multi-level ecological interventions to foster stewardship actions are discussed, as well as directions for future research to further test and refine the model.

  16. A toy model for estimating N2O emissions from natural soils

    NASA Technical Reports Server (NTRS)

    Fung, Inez

    1992-01-01

    A model of N2O emissions from natural soils, whose ultimate objective is to evaluate what contribution natural ecosystems make to the global N2O budget and how the contribution would change with global change, is presented. Topics covered include carbon and nitrogen available in the soil, delivery of nitrifiable N, soil water and oxygen status, soil water budget model, effects of drainage, nitrification and denitrification potentials, soil fertility, N2O production, and a model evaluation. A major implication of the toy model is that the tropics account for more than 80 percent of global emission.

  17. Use of evapotranspiration model based on energy balance in the Ebinur Lake Wetland Nature Reserve

    NASA Astrophysics Data System (ADS)

    Shi, Qingsan; Shi, Qingdong; Wang, Zhi; Gao, Wei; Chang, Shunli

    2009-06-01

    An evapotranspiration model based on the energy balance for different vegetation types in arid area was built in the study, and applied to the natural ecological system of Lake Ebinur wetland nature reserve in Xinjiang. The spatial-temporal dynamic change of the vegetation evapotranspiration in the study area was computed, and the evapotranspiration of three typical vegetations was analyzed and compared. The ground meteorological data were used to test the model. The results show that the evapotranspiration of all the natural system is about 10mm/d, and the maximum is over 20mm/d and occurs between May and August. The evapotranspiration of three typical arid vegetations was estimated in sequence of Populus euphratica Oliv. Tamarix chinensis Lour. Haloxylon ammodendron (Meye)Bge. Finally, it is suggested that the ground surface vegetation types and arid characteristics are most important in the establishment of the evapotranspiration model of natural ecological system based on energy balance in arid areas.

  18. A Three-Component Model Suitable for Natural and Ventilated Cavitation

    NASA Astrophysics Data System (ADS)

    Ji, Bin; Luo, Xian-Wu; Zhang, Yao; Ran, Hong-Juan; Xu, Hong-Yuan; Wu, Yu-Lin

    2010-09-01

    A three-component model based on mass transfer equation is proposed to simulate both the natural and ventilated cavitations. In the present cavitation model, the content of nuclei in the local flow field is updated synchronously, and is coupled with the Rayleigh-Plesset equation so as to capture the cavity development. The proposed model is applied for simulating the cavitating flow around a super-cavitating vehicle in different cavitation conditions. In the case of the natural cavitation simulation, the predicted cavitation characteristics including the cavity length and cavity diameter agrees fairly well with the analytical results. In the case of the mixed cavitation simulation, the gas ventilation obviously influences the development of cavity. With the increase of the gas ventilated rate, the natural cavitation is suppressed remarkably, and a super cavitation is formed even at a relatively larger natural cavitation number.

  19. Northeast United States and Southeast Canada natural mercury emissions estimated with a surface emission model

    NASA Astrophysics Data System (ADS)

    Bash, Jesse O.; Miller, David R.; Meyer, Thomas H.; Bresnahan, Patricia A.

    2004-10-01

    Most mercury emission inventories only include anthropogenic emissions and neglect the large contribution of the natural mercury cycle due to difficulty in spatially estimating natural emissions and uncertainties in the natural emissions process. The Mercury (Hg) Surface Interface Model (HgSIM) has been developed to estimate the natural emissions of mercury, for inclusion in a more complete mercury emissions inventory. The model used a 3422 cell, 36 km on each side, gridded domain and 1 h time steps. The emissions over land are modeled as a function of the land cover, evapotranspiration, and temperature. The emissions over water are modeled as a function of the concentration gradient, the mixing of the air and water, and the temperature. The spatially distributed model is shown to account for the extreme spatial variability across the Northeast (NE) US and Southeast (SE) Canada. Estimates of natural mercury flux from uncontaminated surfaces are presented for a 2 week period in July. The total natural emissions for the domain, 4,434,912 km2, was 2101.5 kg over the 2 week simulation. The highest total natural emissions were 820 ng m-2 from the Atlantic Ocean in the SE part of the domain and the lowest total natural emissions were 74 ng m-2 in the urban areas with little vegetation. The flux estimates from vegetation canopies, averaged over the 14 days, ranged from 0.0 ng m-2 h-1 during the night time hours when transpiration ceased to 4.46 ng m-2 h-1 during the afternoon in a mixed deciduous-coniferous forest. The range of the air-water flux was between 0.5 and 2.73 ng m-2 h-1 over the model domain with the higher emission rates corresponding to windier and warmer areas. The soil emissions ranged from near 0 to 2.3 ng m-2 h-1 with the higher rates corresponding to warmer agricultural regions.

  20. Physical complexity to model morphological changes at a natural channel bend

    NASA Astrophysics Data System (ADS)

    Guan, M.; Wright, N. G.; Sleigh, P. A.; Ahilan, S.; Lamb, R.

    2016-08-01

    This study developed a two-dimensional (2-D) depth-averaged model for morphological changes at natural bends by including a secondary flow correction. The model was tested in two laboratory-scale events. A field study was further adopted to demonstrate the capability of the model in predicting bed deformation at natural bends. Further, a series of scenarios with different setups of sediment-related parameters were tested to explore the possibility of a 2-D model to simulate morphological changes at a natural bend, and to investigate how much physical complexity is needed for reliable modeling. The results suggest that a 2-D depth-averaged model can reconstruct the hydrodynamic and morphological features at a bend reasonably provided that the model addresses a secondary flow correction, and reasonably parameterize grain-sizes within a channel in a pragmatic way. The factors, such as sediment transport formula and roughness height, have relatively less significance on the bed change pattern at a bend. The study reveals that the secondary flow effect and grain-size parameterization should be given a first priority among other parameters when modeling bed deformation at a natural bend using a 2-D model.

  1. Optimum timing for integrated pest management: modelling rates of pesticide application and natural enemy releases.

    PubMed

    Tang, Sanyi; Tang, Guangyao; Cheke, Robert A

    2010-05-21

    Many factors including pest natural enemy ratios, starting densities, timings of natural enemy releases, dosages and timings of insecticide applications and instantaneous killing rates of pesticides on both pests and natural enemies can affect the success of IPM control programmes. To address how such factors influence successful pest control, hybrid impulsive pest-natural enemy models with different frequencies of pesticide sprays and natural enemy releases were proposed and analyzed. With releasing both more or less frequent than the sprays, a stability threshold condition for a pest eradication periodic solution is provided. Moreover, the effects of times of spraying pesticides (or releasing natural enemies) and control tactics on the threshold condition were investigated with regard to the extent of depression or resurgence resulting from pulses of pesticide applications. Multiple attractors from which the pest population oscillates with different amplitudes can coexist for a wide range of parameters and the switch-like transitions among these attractors showed that varying dosages and frequencies of insecticide applications and the numbers of natural enemies released are crucial. To see how the pesticide applications could be reduced, we developed a model involving periodic releases of natural enemies with chemical control applied only when the densities of the pest reached the given Economic Threshold. The results indicate that the pest outbreak period or frequency largely depends on the initial densities and the control tactics.

  2. A simple technique for obtaining future climate data inputs for natural resource models

    USDA-ARS?s Scientific Manuscript database

    Those conducting impact studies using natural resource models need to be able to quickly and easily obtain downscaled future climate data from multiple models, scenarios, and timescales for multiple locations. This paper describes a method of quickly obtaining future climate data over a wide range o...

  3. ESTIMATING THE DISTRIBUTION OF HARVESTED ESTUARINE BIVALVES WITH NATURAL-HISTORY-BASED HABITAT SUITABILITY MODELS.

    EPA Science Inventory

    Habitat suitability models are used to forecast how environmental change may affect the abundance or distribution of species of interest. The development of habitat suitability models may be used to estimate the vulnerability of this valued ecosystem good to natural or anthropog...

  4. A view to the future of natural gas and electricity: An integrated modeling approach

    SciTech Connect

    Cole, Wesley J.; Medlock, Kenneth B.; Jani, Aditya

    2016-03-17

    This paper demonstrates the value of integrating two highly spatially resolved models: the Rice World Gas Trade Model (RWGTM) of the natural gas sector and the Regional Energy Deployment System (ReEDS) model of the U.S. electricity sector. The RWGTM passes electricity-sector natural gas prices to the ReEDS model, while the ReEDS model returns electricity-sector natural gas demand to the RWGTM. The two models successfully converge to a solution under reference scenario conditions. We present electricity-sector and natural gas sector evolution using the integrated models for this reference scenario. This paper demonstrates that the integrated models produced similar national-level results as when running in a stand-alone form, but that regional and state-level results can vary considerably. As we highlight, these regional differences have potentially significant implications for electric sector planners especially in the wake of substantive policy changes for the sector (e.g., the Clean Power Plan).

  5. Model for Naturally Ventilated Cavities on the Exteriors of Opaque Building Thermal Envelopes

    SciTech Connect

    Griffith, B.

    2006-11-01

    This paper describes a model for naturally ventilated cavities on the exterior of opaque building thermal envelopes that are formed by the presence of a lightweight baffle. The model can be used for building components that are slightly detached from the main envelope (but do not connect to the interior).

  6. Harvesting cost model for small trees in natural stands in the interior northwest.

    Treesearch

    Bruce R. Hartsough; Xiaoshan Zhang; Roger D. Fight

    2001-01-01

    Realistic logging cost models are needed for long-term forest management planning. Data from numerous published studies were combined to estimate the costs of harvesting small trees in natural stands in the Interior Northwest of North America. Six harvesting systems were modeled. Four address gentle terrain: manual log-length, manual whole-tree, mechanized whole-tree,...

  7. A Structural Model of Prospective Science Teachers' Nature of Science Views

    ERIC Educational Resources Information Center

    Mugaloglu, Ebru Z.; Bayram, Hale

    2010-01-01

    This study aims to establish a viable structural model of prospective science teachers' nature of science (NOS) views, which could be used as an analytical tool for understanding the complex relationships between prospective teachers' conceptions of NOS and factors possibly affecting their conceptions. In order to construct such a model, likely…

  8. Derivation and Implementation of a Model Teaching the Nature of Science Using Informal Science Education Venues

    ERIC Educational Resources Information Center

    Spector, Barbara S.; Burkett, Ruth; Leard, Cyndy

    2012-01-01

    This paper introduces a model for using informal science education venues as contexts within which to teach the nature of science. The model was initially developed to enable university education students to teach science in elementary schools so as to be consistent with "National Science Education Standards" (NSES) (1996) and "A Framework for…

  9. ESTIMATING THE DISTRIBUTION OF HARVESTED ESTUARINE BIVALVES WITH NATURAL-HISTORY-BASED HABITAT SUITABILITY MODELS.

    EPA Science Inventory

    Habitat suitability models are used to forecast how environmental change may affect the abundance or distribution of species of interest. The development of habitat suitability models may be used to estimate the vulnerability of this valued ecosystem good to natural or anthropog...

  10. A view to the future of natural gas and electricity: An integrated modeling approach

    DOE PAGES

    Cole, Wesley J.; Medlock, Kenneth B.; Jani, Aditya

    2016-03-17

    This paper demonstrates the value of integrating two highly spatially resolved models: the Rice World Gas Trade Model (RWGTM) of the natural gas sector and the Regional Energy Deployment System (ReEDS) model of the U.S. electricity sector. The RWGTM passes electricity-sector natural gas prices to the ReEDS model, while the ReEDS model returns electricity-sector natural gas demand to the RWGTM. The two models successfully converge to a solution under reference scenario conditions. We present electricity-sector and natural gas sector evolution using the integrated models for this reference scenario. This paper demonstrates that the integrated models produced similar national-level results asmore » when running in a stand-alone form, but that regional and state-level results can vary considerably. As we highlight, these regional differences have potentially significant implications for electric sector planners especially in the wake of substantive policy changes for the sector (e.g., the Clean Power Plan).« less

  11. Three-dimensional numerical modeling of water quality and sediment-associated processes in natural lakes

    USDA-ARS?s Scientific Manuscript database

    This chapter presents the development and application of a three-dimensional water quality model for predicting the distributions of nutrients, phytoplankton, dissolved oxygen, etc., in natural lakes. In this model, the computational domain was divided into two parts: the water column and the bed se...

  12. Derivation and Implementation of a Model Teaching the Nature of Science Using Informal Science Education Venues

    ERIC Educational Resources Information Center

    Spector, Barbara S.; Burkett, Ruth; Leard, Cyndy

    2012-01-01

    This paper introduces a model for using informal science education venues as contexts within which to teach the nature of science. The model was initially developed to enable university education students to teach science in elementary schools so as to be consistent with "National Science Education Standards" (NSES) (1996) and "A Framework for…

  13. Estimating the distribution of harvested estuarine bivalves with natural-history-based habitat suitability models

    EPA Science Inventory

    Habitat suitability models are useful to forecast how environmental change may affect the abundance or distribution of species of concern. In the case of harvested bivalves, those models may be used to estimate the vulnerability of this valued ecosystem good to natural or human-...

  14. Estimating the distribution of harvested estuarine bivalves with natural-history-based habitat suitability models

    EPA Science Inventory

    Habitat suitability models are useful to forecast how environmental change may affect the abundance or distribution of species of concern. In the case of harvested bivalves, those models may be used to estimate the vulnerability of this valued ecosystem good to natural or human-...

  15. A Structural Model of Prospective Science Teachers' Nature of Science Views

    ERIC Educational Resources Information Center

    Mugaloglu, Ebru Z.; Bayram, Hale

    2010-01-01

    This study aims to establish a viable structural model of prospective science teachers' nature of science (NOS) views, which could be used as an analytical tool for understanding the complex relationships between prospective teachers' conceptions of NOS and factors possibly affecting their conceptions. In order to construct such a model, likely…

  16. Can natural variability explain observed Antarctic sea ice trends? New modeling evidence from CMIP5

    NASA Astrophysics Data System (ADS)

    Polvani, Lorenzo M.; Smith, Karen L.

    2013-06-01

    The recent observed positive trends in total Antarctic sea ice %extent are at odds with the expectation of melting sea ice in a %warming world. More problematic yet, climate models indicate that sea %ice should decrease around Antarctica in response to both increasing %greenhouse gases and stratospheric ozone depletion. The resolution of %this puzzle, we suggest, may lie in the large natural variability of %the coupled atmosphere-ocean-sea-ice system. Contrasting forced and control integrations from four state-of-the-art Coupled Model Intercomparison Project Phase 5 (CMIP5) models, we show that the observed Antarctic sea ice trend falls well within the distribution of trends arising naturally in the system, and that the forced response in the models is small compared to the natural variability. From this, we conclude that it may prove difficult to attribute the observed trends in total Antarctic sea ice to anthropogenic forcings, although some regional features might be easier to explain.

  17. From Sequential Extraction to Transport Modeling, Monitored Natural Attenuation as a Remediation Approach for Inorganic Contaminants

    SciTech Connect

    POWELL, KIMBERLYR.

    2004-05-25

    Implementation of monitored natural attenuation (MNA) as a remediation method requires a mechanistic understanding of the natural attenuation processes occurring at a given site. For inorganic contaminants, natural attenuation typically involves a decrease in metal toxicity and/or mobility. These natural processes include dilution, dispersion, sorption (including adsorption, absorption, and precipitation), and redox processes. In order to better quantify these processes in terms of metal availability, sequential extraction experiments were carried out on subsurface soil samples impacted by a low pH, high sulfate, metals (Be, Ni, U, As) plume associated with the long-term operation of a coal plant at the Savannah River Site. These laboratory scale studies provide mechanistic information regarding the solid phases in the soils associated with natural attenuation of the contaminant metals. This data provides input to be evaluated in the definition of the contaminant source term as well as transport of contaminants for site transport models.

  18. Object detection in natural backgrounds predicted by discrimination performance and models

    NASA Technical Reports Server (NTRS)

    Rohaly, A. M.; Ahumada, A. J. Jr; Watson, A. B.

    1997-01-01

    Many models of visual performance predict image discriminability, the visibility of the difference between a pair of images. We compared the ability of three image discrimination models to predict the detectability of objects embedded in natural backgrounds. The three models were: a multiple channel Cortex transform model with within-channel masking; a single channel contrast sensitivity filter model; and a digital image difference metric. Each model used a Minkowski distance metric (generalized vector magnitude) to summate absolute differences between the background and object plus background images. For each model, this summation was implemented with three different exponents: 2, 4 and infinity. In addition, each combination of model and summation exponent was implemented with and without a simple contrast gain factor. The model outputs were compared to measures of object detectability obtained from 19 observers. Among the models without the contrast gain factor, the multiple channel model with a summation exponent of 4 performed best, predicting the pattern of observer d's with an RMS error of 2.3 dB. The contrast gain factor improved the predictions of all three models for all three exponents. With the factor, the best exponent was 4 for all three models, and their prediction errors were near 1 dB. These results demonstrate that image discrimination models can predict the relative detectability of objects in natural scenes.

  19. Object detection in natural backgrounds predicted by discrimination performance and models

    NASA Technical Reports Server (NTRS)

    Rohaly, A. M.; Ahumada, A. J. Jr; Watson, A. B.

    1997-01-01

    Many models of visual performance predict image discriminability, the visibility of the difference between a pair of images. We compared the ability of three image discrimination models to predict the detectability of objects embedded in natural backgrounds. The three models were: a multiple channel Cortex transform model with within-channel masking; a single channel contrast sensitivity filter model; and a digital image difference metric. Each model used a Minkowski distance metric (generalized vector magnitude) to summate absolute differences between the background and object plus background images. For each model, this summation was implemented with three different exponents: 2, 4 and infinity. In addition, each combination of model and summation exponent was implemented with and without a simple contrast gain factor. The model outputs were compared to measures of object detectability obtained from 19 observers. Among the models without the contrast gain factor, the multiple channel model with a summation exponent of 4 performed best, predicting the pattern of observer d's with an RMS error of 2.3 dB. The contrast gain factor improved the predictions of all three models for all three exponents. With the factor, the best exponent was 4 for all three models, and their prediction errors were near 1 dB. These results demonstrate that image discrimination models can predict the relative detectability of objects in natural scenes.

  20. Models, Simulators, and Data-driven Resources for Oil and Natural Gas Research

    DOE Data Explorer

    NETL provides a number of analytical tools to assist in conducting oil and natural gas research. Software, developed under various DOE/NETL projects, includes numerical simulators, analytical models, databases, and documentation.[copied from http://www.netl.doe.gov/technologies/oil-gas/Software/Software_main.html] Links lead users to methane hydrates models, preedictive models, simulators, databases, and other software tools or resources.

  1. Comparative characterization of the microbial diversities of an artificial microbialite model and a natural stromatolite.

    PubMed

    Havemann, Stephanie A; Foster, Jamie S

    2008-12-01

    Microbialites are organosedimentary structures that result from the trapping, binding, and lithification of sediments by microbial mat communities. In this study we developed a model artificial microbialite system derived from natural stromatolites, a type of microbialite, collected from Exuma Sound, Bahamas. We demonstrated that the morphology of the artificial microbialite was consistent with that of the natural system in that there was a multilayer community with a pronounced biofilm on the surface, a concentrated layer of filamentous cyanobacteria in the top 5 mm, and a lithified layer of fused oolitic sand grains in the subsurface. The fused grain layer was comprised predominantly of the calcium carbonate polymorph aragonite, which corresponded to the composition of the Bahamian stromatolites. The microbial diversity of the artificial microbialites and that of natural stromatolites were also compared using automated ribosomal intergenic spacer analysis (ARISA) and 16S rRNA gene sequencing. The ARISA profiling indicated that the Shannon indices of the two communities were comparable and that the overall diversity was not significantly lower in the artificial microbialite model. Bacterial clone libraries generated from each of the three artificial microbialite layers and natural stromatolites indicated that the cyanobacterial and crust layers most closely resembled the ecotypes detected in the natural stromatolites and were dominated by Proteobacteria and Cyanobacteria. We propose that such model artificial microbialites can serve as experimental analogues for natural stromatolites.

  2. Electroweak naturalness in the three-flavor type I seesaw model and implications for leptogenesis

    NASA Astrophysics Data System (ADS)

    Clarke, Jackson D.; Foot, Robert; Volkas, Raymond R.

    2015-04-01

    In the type I seesaw model, the naturalness requirement that corrections to the electroweak μ parameter not exceed 1 TeV results in a rough bound on the lightest right-handed neutrino mass, MN1≲3 ×1 07 GeV . In this paper we derive generic bounds applicable in any three-flavor type I seesaw model. We find MN1≲4 ×1 07 GeV and MN2≲7 ×1 07 GeV . In the limit of one massless neutrino, there is no naturalness bound on MN 3 in the Poincaré protected decoupling limit. Our results confirm that no type I seesaw model can explain the observed neutrino masses and baryogenesis via hierarchical (N1-, N2-, or N3-dominated) thermal leptogenesis while remaining completely natural.

  3. Predicting the natural flow regime: Models for assessing hydrological alteration in streams

    USGS Publications Warehouse

    Carlisle, D.M.; Falcone, J.; Wolock, D.M.; Meador, M.R.; Norris, R.H.

    2010-01-01

    Understanding the extent to which natural streamflow characteristics have been altered is an important consideration for ecological assessments of streams. Assessing hydrologic condition requires that we quantify the attributes of the flow regime that would be expected in the absence of anthropogenic modifications. The objective of this study was to evaluate whether selected streamflow characteristics could be predicted at regional and national scales using geospatial data. Long-term, gaged river basins distributed throughout the contiguous US that had streamflow characteristics representing least disturbed or near pristine conditions were identified. Thirteen metrics of the magnitude, frequency, duration, timing and rate of change of streamflow were calculated using a 20-50 year period of record for each site. We used random forests (RF), a robust statistical modelling approach, to develop models that predicted the value for each streamflow metric using natural watershed characteristics. We compared the performance (i.e. bias and precision) of national- and regional-scale predictive models to that of models based on landscape classifications, including major river basins, ecoregions and hydrologic landscape regions (HLR). For all hydrologic metrics, landscape stratification models produced estimates that were less biased and more precise than a null model that accounted for no natural variability. Predictive models at the national and regional scale performed equally well, and substantially improved predictions of all hydrologic metrics relative to landscape stratification models. Prediction error rates ranged from 15 to 40%, but were 25% for most metrics. We selected three gaged, non-reference sites to illustrate how predictive models could be used to assess hydrologic condition. These examples show how the models accurately estimate predisturbance conditions and are sensitive to changes in streamflow variability associated with long-term land-use change. We also

  4. Estimating Risk of Natural Gas Portfolios by Using GARCH-EVT-Copula Model.

    PubMed

    Tang, Jiechen; Zhou, Chao; Yuan, Xinyu; Sriboonchitta, Songsak

    2015-01-01

    This paper concentrates on estimating the risk of Title Transfer Facility (TTF) Hub natural gas portfolios by using the GARCH-EVT-copula model. We first use the univariate ARMA-GARCH model to model each natural gas return series. Second, the extreme value distribution (EVT) is fitted to the tails of the residuals to model marginal residual distributions. Third, multivariate Gaussian copula and Student t-copula are employed to describe the natural gas portfolio risk dependence structure. Finally, we simulate N portfolios and estimate value at risk (VaR) and conditional value at risk (CVaR). Our empirical results show that, for an equally weighted portfolio of five natural gases, the VaR and CVaR values obtained from the Student t-copula are larger than those obtained from the Gaussian copula. Moreover, when minimizing the portfolio risk, the optimal natural gas portfolio weights are found to be similar across the multivariate Gaussian copula and Student t-copula and different confidence levels.

  5. Estimating Risk of Natural Gas Portfolios by Using GARCH-EVT-Copula Model

    PubMed Central

    Tang, Jiechen; Zhou, Chao; Yuan, Xinyu; Sriboonchitta, Songsak

    2015-01-01

    This paper concentrates on estimating the risk of Title Transfer Facility (TTF) Hub natural gas portfolios by using the GARCH-EVT-copula model. We first use the univariate ARMA-GARCH model to model each natural gas return series. Second, the extreme value distribution (EVT) is fitted to the tails of the residuals to model marginal residual distributions. Third, multivariate Gaussian copula and Student t-copula are employed to describe the natural gas portfolio risk dependence structure. Finally, we simulate N portfolios and estimate value at risk (VaR) and conditional value at risk (CVaR). Our empirical results show that, for an equally weighted portfolio of five natural gases, the VaR and CVaR values obtained from the Student t-copula are larger than those obtained from the Gaussian copula. Moreover, when minimizing the portfolio risk, the optimal natural gas portfolio weights are found to be similar across the multivariate Gaussian copula and Student t-copula and different confidence levels. PMID:26351652

  6. Depletion of natural killer cells increases mice susceptibility in a Pseudomonas aeruginosa pneumonia model.

    PubMed

    Broquet, Alexis; Roquilly, Antoine; Jacqueline, Cédric; Potel, Gilles; Caillon, Jocelyne; Asehnoune, Karim

    2014-06-01

    Pseudomonas aeruginosa infection is a clinically relevant infection involved in pneumonia in ICUs. Understanding the type of immune response initiated by the host during pneumonia would help defining new strategies to interfere with the bacteria pathogenicity. In this setting, the role of natural killer cells remains controversial. We assessed the role of systemic natural killer cells in a Pseudomonas aeruginosa mouse pneumonia model. Experimental study. Research laboratory from a university hospital. RjOrl:SWISS and BALB/cJ mice (weight, 20-24 g). Lung injuries were assessed by bacterial load, myeloperoxidase activity, endothelial permeability (pulmonary edema), immune cell infiltrate (histological analysis), proinflammatory cytokine release, and Ly6-G immunohistochemistry. Bacterial loads were assessed in the lungs and spleen. Natural killer cell number and status were assessed in spleen (flow cytometry and quantitative polymerase chain reaction). Depletion of natural killer cells was achieved through an IV anti-asialo-GM1 antibody injection. Pseudomonas aeruginosa tracheal instillation led to an acute pneumonia with a rapid decrease of bacterial load in lungs and with an increase of endothelial permeability, proinflammatory cytokines (tumor necrosis factor-α and interleukin-1β), and myeloperoxidase activity followed by Ly6-G positive cell infiltrate in lungs. Pseudomonas aeruginosa was detected in the spleen. Membrane markers of activation and maturation (CD69 and KLRG1 molecules) were increased in splenic natural killer cells during Pseudomonas aeruginosa infection. Splenic natural killer cells activated upon Pseudomonas aeruginosa infection produced interferon-γ but not interleukin-10. Ultimately, mice depleted of natural killer cells displayed an increased neutrophil numbers in the lungs and an increased mortality rate without bacterial load modifications in the lungs, indicating that mice depleted of natural killer cells were much more susceptible to

  7. Modeling Images of Natural 3D Surfaces: Overview and Potential Applications

    NASA Technical Reports Server (NTRS)

    Jalobeanu, Andre; Kuehnel, Frank; Stutz, John

    2004-01-01

    Generative models of natural images have long been used in computer vision. However, since they only describe the of 2D scenes, they fail to capture all the properties of the underlying 3D world. Even though such models are sufficient for many vision tasks a 3D scene model is when it comes to inferring a 3D object or its characteristics. In this paper, we present such a generative model, incorporating both a multiscale surface prior model for surface geometry and reflectance, and an image formation process model based on realistic rendering, the computation of the posterior model parameter densities, and on the critical aspects of the rendering. We also how to efficiently invert the model within a Bayesian framework. We present a few potential applications, such as asteroid modeling and Planetary topography recovery, illustrated by promising results on real images.

  8. An ontology model for nursing narratives with natural language generation technology.

    PubMed

    Min, Yul Ha; Park, Hyeoun-Ae; Jeon, Eunjoo; Lee, Joo Yun; Jo, Soo Jung

    2013-01-01

    The purpose of this study was to develop an ontology model to generate nursing narratives as natural as human language from the entity-attribute-value triplets of a detailed clinical model using natural language generation technology. The model was based on the types of information and documentation time of the information along the nursing process. The typesof information are data characterizing the patient status, inferences made by the nurse from the patient data, and nursing actions selected by the nurse to change the patient status. This information was linked to the nursing process based on the time of documentation. We describe a case study illustrating the application of this model in an acute-care setting. The proposed model provides a strategy for designing an electronic nursing record system.

  9. A Modeling Approach for Burn Scar Assessment Using Natural Features and Elastic Property

    SciTech Connect

    Tsap, L V; Zhang, Y; Goldgof, D B; Sarkar, S

    2004-04-02

    A modeling approach is presented for quantitative burn scar assessment. Emphases are given to: (1) constructing a finite element model from natural image features with an adaptive mesh, and (2) quantifying the Young's modulus of scars using the finite element model and the regularization method. A set of natural point features is extracted from the images of burn patients. A Delaunay triangle mesh is then generated that adapts to the point features. A 3D finite element model is built on top of the mesh with the aid of range images providing the depth information. The Young's modulus of scars is quantified with a simplified regularization functional, assuming that the knowledge of scar's geometry is available. The consistency between the Relative Elasticity Index and the physician's rating based on the Vancouver Scale (a relative scale used to rate burn scars) indicates that the proposed modeling approach has high potentials for image-based quantitative burn scar assessment.

  10. COBRA-WC model and predictions for a fast-reactor natural-circulation transient. [LMFBR

    SciTech Connect

    George, T.L.; Basehore, K.L.; Prather, W.A.

    1980-01-01

    The COBRA-WC (Whole Core) code has been used to predict the core-wide coolant and rod temperature distribution in a liquid metal fast reactor during the early part (first 220 seconds) of a natural circulation transient. Approximately one-sixth of the core was modeled including bypass flows and the pressure losses above and below the core region. Detailed temperature and flow distributions were obtained for the two test fuel assemblies. The COBRA-WC model, the approach, and predictions of core-wide transient coolant and rod temperatures during a natural circulation transient are presented in this paper.

  11. Model-Based Nonrigid Motion Analysis Using Natural Feature Adaptive Mesh

    SciTech Connect

    Zhang, Y.; Goldgof, D.B.; Sarkar, S.; Tsap, L.V.

    2000-04-25

    The success of nonrigid motion analysis using physical finite element model is dependent on the mesh that characterizes the object's geometric structure. We suggest a deformable mesh adapted to the natural features of images. The adaptive mesh requires much fewer number of nodes than the fixed mesh which was used in our previous work. We demonstrate the higher efficiency of the adaptive mesh in the context of estimating burn scar elasticity relative to normal skin elasticity using the observed 2D image sequence. Our results show that the scar assessment method based on the physical model using natural feature adaptive mesh can be applied to images which do not have artificial markers.

  12. Generalized focus point and mass spectra comparison of highly natural SUGRA GUT models

    NASA Astrophysics Data System (ADS)

    Baer, Howard; Barger, Vernon; Savoy, Michael

    2016-04-01

    Supergravity grand unified models (SUGRA GUTs) are highly motivated and allow for a high degree of electroweak naturalness when the superpotential parameter μ ˜100 - 300 GeV (preferring values closer to 100 GeV). We first illustrate that models with radiatively driven naturalness enjoy a generalized focus-point behavior wherein all soft terms are correlated instead of just scalar masses. Next, we generate spectra from four SUGRA GUT archetypes: 1. S O (10 ) models where the Higgs doublets live in different ten-dimensional irreducible representations (irreps), 2. models based on S O (10 ) where the Higgs multiplets live in a single ten-dimensional irrep but with D -term scalar mass splitting, 3. models based on S U (5 ), and 4. a more general SUGRA model with 12 independent parameters. Electroweak naturalness implies for all models a spectrum of light Higgsinos with mW˜1,Z˜ 1 ,2≲300 GeV and gluinos with mg ˜≲ 2 - 4 TeV . However, masses and mixing in the third generation sfermion sector differ distinctly between the models. These latter differences would be most easily tested at a linear e+e- collider with √{s }˜ multi-TeV scale but measurements at a 50-100 TeV hadron collider are also possible.

  13. Evaluation of Two Different k-e-vv-f Turbulence Models for Natural Convection in a Rectangular Cavity

    DTIC Science & Technology

    2005-04-14

    algebraic flux model (AFM hereafter) together with the low-Reynolds number turbulence model and applied it to the prediction of various natural...fvvk −−− ε model developed by Durbin [1] in the present study. Durbin [1] developed a fvvk −−−ε model around the elliptic relaxation method for... algebraic flux model for the natural convection problem. The relative performances between the original model and the modified model are investigated 2

  14. Influence of dissolved organic carbon content on modelling natural organic matter acid-base properties.

    PubMed

    Garnier, Cédric; Mounier, Stéphane; Benaïm, Jean Yves

    2004-10-01

    Natural organic matter (NOM) behaviour towards proton is an important parameter to understand NOM fate in the environment. Moreover, it is necessary to determine NOM acid-base properties before investigating trace metals complexation by natural organic matter. This work focuses on the possibility to determine these acid-base properties by accurate and simple titrations, even at low organic matter concentrations. So, the experiments were conducted on concentrated and diluted solutions of extracted humic and fulvic acid from Laurentian River, on concentrated and diluted model solutions of well-known simple molecules (acetic and phenolic acids), and on natural samples from the Seine river (France) which are not pre-concentrated. Titration experiments were modelled by a 6 acidic-sites discrete model, except for the model solutions. The modelling software used, called PROSECE (Programme d'Optimisation et de SpEciation Chimique dans l'Environnement), has been developed in our laboratory, is based on the mass balance equilibrium resolution. The results obtained on extracted organic matter and model solutions point out a threshold value for a confident determination of the studied organic matter acid-base properties. They also show an aberrant decreasing carboxylic/phenolic ratio with increasing sample dilution. This shift is neither due to any conformational effect, since it is also observed on model solutions, nor to ionic strength variations which is controlled during all experiments. On the other hand, it could be the result of an electrode troubleshooting occurring at basic pH values, which effect is amplified at low total concentration of acidic sites. So, in our conditions, the limit for a correct modelling of NOM acid-base properties is defined as 0.04 meq of total analysed acidic sites concentration. As for the analysed natural samples, due to their high acidic sites content, it is possible to model their behaviour despite the low organic carbon concentration.

  15. Applying the Land Use Portfolio Model with Hazus to analyse risk from natural hazard events

    USGS Publications Warehouse

    Dinitz, Laura B.; Taketa, Richard A.

    2013-01-01

    This paper describes and demonstrates the integration of two geospatial decision-support systems for natural-hazard risk assessment and management. Hazus is a risk-assessment tool developed by the Federal Emergency Management Agency to identify risks and estimate the severity of risk from natural hazards. The Land Use Portfolio Model (LUPM) is a risk-management tool developed by the U.S. Geological Survey to evaluate plans or actions intended to reduce risk from natural hazards. We analysed three mitigation policies for one earthquake scenario in the San Francisco Bay area to demonstrate the added value of using Hazus and the LUPM together. The demonstration showed that Hazus loss estimates can be input to the LUPM to obtain estimates of losses avoided through mitigation, rates of return on mitigation investment, and measures of uncertainty. Together, they offer a more comprehensive approach to help with decisions for reducing risk from natural hazards.

  16. [Hyperspectral remote sensing estimation models on vegetation coverage of natural grassland].

    PubMed

    Liu, Zhanyu; Huang, Jingfeng; Wu, Xinhong; Dong, Yongping; Wang, Fumin; Liu, Pengtao

    2006-06-01

    By using ASD FieldSpec Pro FR spectroradiometer, the spectral measurement of natural grassland in Xilingole Leaguer of Inner Mongolia was performed, with the vegetation coverage of natural grassland calculated, and the correlation of 25 hyperspectral feature variables with the vegetation coverage of natural grassland was analyzed. The results showed that there were 17 variables correlated significantly with the vegetation coverage of natural grassland, among which, the correlation coefficient between vegetation coverage and the area of red edge peak calculated as the sum of the amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the highest, with the value of 0.781. The basic experimental data including the vegetation coverage and canopy reflectance of natural grassland were classified into two groups. One group was used as the training sample to build the regression models with one-sample linear method, nonlinear method, and stepwise analysis method, while the other was used as the testing sample to test the precision of regression models. It was suggested that the variable of the area of red edge peak calculated as the sum of amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the best one to univariate general linear model, with a standard deviation of 10.4% and an estimation precision of 83.99%, while the stepwise regression technique was not effective to estimate the grassland coverage with raw hyperspectral canopy reflectance.

  17. [Clinical pilot study of HPV6b L1 virus-like particles as immune therapy for juvenile larynx papillomatosis].

    PubMed

    Chen, Bobei; Zhao, Kongnan; Liu, Xiaosong; Xu, Yan; Xiang, Songjie; Yang, Jihong; Chen, Xiaofang

    2004-09-01

    To study the safety and the immunogenicity of HPV6b virus-like particles (VLP) in children with juvenile laryngeal papilloma (JLP). The result of therapy is observed. HPV6b VLP were expressed with HPV6b L1 recombinant baculovirus in sf-9 insect cells. Ten case of recurrent JLP were immunized with HPV6b VLP in 5, 10, 25 microg doses progressively and any local or systemic adverse events were recorded. By ELISA was used to detect the serum HPV6b VLP antibody (Ab) of JLPs samples in therapy different stage. Seven cases of JLP were used DTH test. To understand the effects of VLP on disease prognosis subjects will be examined by fibrolaryngoscope. All subjects did not experience local or systemic adverse events and specific serum antibody against HPV6b L1VLP was produced in JLP immunized. The A value of sera antibody in the first dose group have completed (0.310 +/- 0.012) were higher than that of pro-immune (0.110 +/- 0.035) (t = 4.673, P < 0.01). There was a significant difference of serum mean HPV6b Ab A value between JLP's patients immunized (0.772 +/- 0.013) and the control group (0.153 +/- 0.014) (t = 15.45, P < 0.01), 7 samples have male response of DTH test. All patients didn't recurrent papilloma after receiving treatment. HPV6b VLP have immunogenicity and safety as therapy for JLP patients, and HPV6b VLP may be used in prophylactic and therapeutic vaccine for JLP.

  18. Occurrence of the structural enterocin A, P, B, L50B genes in enterococci of different origin.

    PubMed

    Strompfová, Viola; Lauková, Andrea; Simonová, Monika; Marcináková, Miroslava

    2008-12-10

    Enterococci are well-known producers of antimicrobial peptides--bacteriocins (enterocins) and the number of characterized enterocins has been significantly increased. Recently, enterocins are of great interest for their potential as biopreservatives in food or feed while research on enterocins as alternative antimicrobials in humans and animals is only at the beginning. The present study provides a survey about the occurrence of enterocin structural genes A, P, B, L50B in a target of 427 strains of Enterococcus faecium (368) and Enterococcus faecalis (59) species from different sources (animal isolates, food and feed) performed by PCR method. Based on our results, 234 strains possessed one or more enterocin structural gene(s). The genes of enterocin P and enterocin A were the most frequently detected structural genes among the PCR positive strains (170 and 155 strains, respectively). Different frequency of the enterocin genes occurrence was detected in strains according to their origin; the strains from horses and silage showed the highest frequency of enterocin genes presence. All possible combinations of the tested genes occurred at least twice except the combination of the gene of enterocin B and L50B which possessed neither strain. The gene of enterocin A was exclusively detected among E. faecium strains, while the gene of enterocin P, B, L50B were detected in strains of both species E. faecium and E. faecalis. In conclusion, a high-frequency and variability of enterocin structural genes exists among enterococci of different origin what offers a big possibility to find effective bacteriocin-producing strains for their application in veterinary medicine.

  19. Thermodynamic nature of vitrification in a 1D model of a structural glass former

    SciTech Connect

    Semenov, A. N.

    2015-07-28

    We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.

  20. Thermodynamic nature of vitrification in a 1D model of a structural glass former

    NASA Astrophysics Data System (ADS)

    Semenov, A. N.

    2015-07-01

    We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.

  1. Thermodynamic nature of vitrification in a 1D model of a structural glass former.

    PubMed

    Semenov, A N

    2015-07-28

    We propose a new spin-glass model with no positional quenched disorder which is regarded as a coarse-grained model of a structural glass-former. The model is analyzed in the 1D case when the number N of states of a primary cell is large. For N → ∞, the model exhibits a sharp freezing transition of the thermodynamic origin. It is shown both analytically and numerically that the glass transition is accompanied by a significant growth of a static length scale ξ pointing to the structural (equilibrium) nature of dynamical slowdown effects in supercooled liquids.

  2. Structural bonding-breakage constitutive model for natural unsaturated clayey soils

    NASA Astrophysics Data System (ADS)

    Cai, Guo-Qing; Zhao, Cheng-Gang; Qin, Xiao-Ming

    2010-12-01

    The natural clayey soils are usually structural and unsaturated, which makes their mechanical properties quite different from the remolded saturated soils. A structural constitutive model is proposed to simulate the bonding-breakage micro-mechanism. In this model, the unsaturated soil element is divided into a cementation element and a friction element according to the binary medium theory, and the stress-strain coordination for these two elements is obtained. The cementation element is regarded as elastic, whereas the friction element is regarded as elastoplastic which can be described with the Gallipoli's model. The theoretical formulation is verified with the comparative experiments of isotropic compressions on the saturated and unsaturated structural soils. Parametric analyses of the effects of damage variables on the model predictions are further carried out, which show that breakage deformation of natural clayey soils increases with the rising amount of initial defects.

  3. Learning nonlinear statistical regularities in natural images by modeling the outer product of image intensities.

    PubMed

    Qi, Peng; Hu, Xiaolin

    2014-04-01

    It is well known that there exist nonlinear statistical regularities in natural images. Existing approaches for capturing such regularities always model the image intensities by assuming a parameterized distribution for the intensities and learn the parameters. In the letter, we propose to model the outer product of image intensities by assuming a gaussian distribution for it. A two-layer structure is presented, where the first layer is nonlinear and the second layer is linear. Trained on natural images, the first-layer bases resemble the receptive fields of simple cells in the primary visual cortex (V1), while the second-layer units exhibit some properties of the complex cells in V1, including phase invariance and masking effect. The model can be seen as an approximation of the covariance model proposed in Karklin and Lewicki (2009) but has more robust and efficient learning algorithms.

  4. A model of natural image edge co-occurrence in the rototranslation group.

    PubMed

    Sanguinetti, Gonzalo; Citti, Giovanna; Sarti, Alessandro

    2010-12-31

    In this paper, we propose to model the edge information contained in natural scenes as points in the 3D space of positions and orientations. This space is equipped with a strong geometrical structure and it is identified as the rototranslation group. In this space, we compute a histogram of co-occurrence of edges from a database of natural images and show that it can be interpreted as a probability density function, expressed by the fundamental solution of a suitable Fokker-Planck equation defined in the 3D structured space. Both estimated statistics and model predictions are reconsidered and compared with the partial gestalt association fields proposed by D. J. Field, A. Hayes, and R. F. Hess (1993). Finally, parametric identification allows to estimate the variance of the co-occurrence random process in natural images.

  5. Review of selected features of the natural system model, and suggestions for applications in South Florida

    USGS Publications Warehouse

    Bales, Jerad; Fulford, Janice M.; Swain, Eric D.

    1997-01-01

    A study was conducted to review selected features of the Natural System Model, version 4.3 . The Natural System Model is a regional-scale model that uses recent climatic data and estimates of historic vegetation and topography to simulate pre-canal-drainage hydrologic response in south Florida. Equations used to represent the hydrologic system and the numerical solution of these equations in the model were documented and reviewed. Convergence testing was performed using 1965 input data, and selected other aspects of the model were evaluated.Some conclusions from the evaluation of the Natural System Model include the following observations . Simulations were generally insensitive to the temporal resolution used in the model. However, reduction of the computational cell size from 2-mile by 2-mile to 2/3-mile by 2/3-mile resulted in a decrease in spatial mean ponding depths for October of 0.35 foot for a 3-hour time step.Review of the computer code indicated that there is no limit on the amount of water that can be transferred from the river system to the overland flow system, on the amount of seepage from the river to the ground-water system, on evaporation from the river system, or on evapotranspiration from the overland-flow system . Oscillations of 0.2 foot or less in simulated river stage were identified and attributed to a volume limiting function which is applied in solution of the overland-flow equations. The computation of the resistance coefficient is not consistent with the computation of overland-flow velocity. Ground-water boundary conditions do not always ensure a no-flow condition at the boundary. These inconsistencies had varying degrees of effects on model simulations, and it is likely that simulations longer than 1 year are needed to fully identify effects. However, inconsistencies in model formulations should not be ignored, even if the effects of such errors on model results appear to be small or have not been clearly defined.The Natural System

  6. Multi-agent social and organizational modeling of the electric power and natural gas markets.

    SciTech Connect

    North, M. J.; Decision and Information Sciences

    2001-12-01

    Complex Adaptive Systems (CAS) can be applied to investigate large-scale socio-cognitive-technical systems. Viewing such systems from a multi-agent social and organizational perspective allows innovative computational policy analysis. Argonne National Laboratory (ANL) has taken such a perspective to produce an integrated model of the electric power and natural gas markets. This model focuses on the organizational interdependencies between these markets. These organizational interdependencies are being strained by fundamental market transformations.

  7. Teaching Mathematics with Intelligent Support in Natural Language. Tertiary Education Students Working with Parametrized Modelling Activities

    ERIC Educational Resources Information Center

    Rojano, Teresa; García-Campos, Montserrat

    2017-01-01

    This article reports the outcomes of a study that seeks to investigate the role of feedback, by way of an intelligent support system in natural language, in parametrized modelling activities carried out by a group of tertiary education students. With such a system, it is possible to simultaneously display on a computer screen a dialogue window and…

  8. Modeling the Time-Varying Nature of Student Exceptionality Classification on Achievement Growth

    ERIC Educational Resources Information Center

    Nese, Joseph F. T.; Stevens, Joseph J.; Schulte, Ann C.; Tindal, Gerald; Elliott, Stephen N.

    2017-01-01

    Our purpose was to examine different approaches to modeling the time-varying nature of exceptionality classification. Using longitudinal data from one state's mathematics achievement test for 28,829 students in Grades 3 to 8, we describe the reclassification rate within special education and between general and special education, and compare four…

  9. A Geometric Model to Teach Nature of Science, Science Practices, and Metacognition

    ERIC Educational Resources Information Center

    Nyman, Matthew; St. Clair, Tyler

    2016-01-01

    Using the science practice model in science classes for preservice teachers addresses three important aspects of science teacher preparation: teaching the nonlinear nature of scientific process, using scientific practices rather than the ambiguous term "inquiry-based," and emphasizing the process of metacognition as an important tool in…

  10. New technologies of 2-D and 3-D modeling for analysis and management of natural resources

    NASA Astrophysics Data System (ADS)

    Cheremisina, E. N.; Lyubimova, A. V.; Kirpicheva, E. Yu.

    2016-09-01

    For ensuring technological support of research and administrative activity in the sphere of environmental management a specialized modular program complex was developed. The special attention in developing a program complex is focused to creation of convenient and effective tools for creation and visualization 2d and 3D models providing the solution of tasks of the analysis and management of natural resources.

  11. The Wave Model of Linguistic Change and the Naturalness of Interlanguage.

    ERIC Educational Resources Information Center

    Zobl, Helmut

    1984-01-01

    Investigates whether the Wave Model of linguistic change can furnish a valid idealization for the patterning of variation in interlanguage systems and a scale for determining degree of naturalness. Data from 162 French-speaking adult learners were used to analyze the variability in the evolution of the English possessive determiners…

  12. Utilizing Natural Structure of the Research Literature in Psychology as a Model for Bibliographic Instruction.

    ERIC Educational Resources Information Center

    Olivetti, L. James

    1979-01-01

    Offered as an alternative to the search strategy model for bibliographic instruction, the approach to library instruction in psychology which is described involves analysis of the natural structure of the research literature. An example using Festinger's theory of cognitive dissonance is presented. Twelve references are cited. (EJS)

  13. Multi-criteria decision models for forestry and natural resources management: an annotated bibliography

    Treesearch

    Joseph E. de Steiguer; Leslie Liberti; Albert Schuler; Bruce Hansen

    2003-01-01

    Foresters and natural resource managers must balance conflicting objectives when developing land-management plans. Conflicts may encompass economic, environmental, social, cultural, technical, and aesthetic objectives. Selecting the best combination of management uses from numerous objectives is difficult and challenging. Multi-Criteria Decision Models (MCDM) provide a...

  14. A Bending Willow Tree: A Japanese (Morita Therapy) Model of Human Nature and Client Change.

    ERIC Educational Resources Information Center

    Ishiyama, F. Ishu

    2003-01-01

    Japanese Morita therapy is discussed to highlight its culturally and theoretically unique perspectives on human nature and client change. Key features of this theory are: theory of the nervous trait; multiple-dimensional model of causes and treatment of nervous neurosis; theory of mental attachment; reframing anxiety into constructive desires; and…

  15. Site index model for naturally regenerated even-aged longleaf pine

    Treesearch

    Dwight K. Lauer; John S. Kush

    2013-01-01

    Data from the Regional Longleaf Growth Study (339 permanent sample plots) were used to develop a site index model for naturally regenerated, even-aged longleaf pine (Pinus palustris Mill.). The site index equation was derived using the generalized algebraic difference approach and is base-age invariant. Using height as a measure of site productivity...

  16. A Geometric Model to Teach Nature of Science, Science Practices, and Metacognition

    ERIC Educational Resources Information Center

    Nyman, Matthew; St. Clair, Tyler

    2016-01-01

    Using the science practice model in science classes for preservice teachers addresses three important aspects of science teacher preparation: teaching the nonlinear nature of scientific process, using scientific practices rather than the ambiguous term "inquiry-based," and emphasizing the process of metacognition as an important tool in…

  17. Students' Evaluation of the Credibility of Scientific Models that Represent Natural Entities and Phenomena

    ERIC Educational Resources Information Center

    Al-Balushi, Sulaiman M.

    2011-01-01

    The purpose of the current study was to explore learners' evaluation of the credibility of scientific models that represent natural entities and phenomena. Participants were 845 students in grades 9-11 (aged 15-17 years) and 108 prospective science teachers in Oman, totaling 953 students. A survey called Epistemologies about the Credibility of…

  18. Utilizing Natural Structure of the Research Literature in Psychology as a Model for Bibliographic Instruction.

    ERIC Educational Resources Information Center

    Olivetti, L. James

    1979-01-01

    Offered as an alternative to the search strategy model for bibliographic instruction, the approach to library instruction in psychology which is described involves analysis of the natural structure of the research literature. An example using Festinger's theory of cognitive dissonance is presented. Twelve references are cited. (EJS)

  19. Students' Evaluation of the Credibility of Scientific Models that Represent Natural Entities and Phenomena

    ERIC Educational Resources Information Center

    Al-Balushi, Sulaiman M.

    2011-01-01

    The purpose of the current study was to explore learners' evaluation of the credibility of scientific models that represent natural entities and phenomena. Participants were 845 students in grades 9-11 (aged 15-17 years) and 108 prospective science teachers in Oman, totaling 953 students. A survey called Epistemologies about the Credibility of…

  20. Zebrafish Embryo Toxicity Microscale Model for Ichthyotoxicity Evaluation of Marine Natural Products.

    PubMed

    Bai, Hong; Kong, Wen-Wen; Shao, Chang-Lun; Li, Yun; Liu, Yun-Zhang; Liu, Min; Guan, Fei-Fei; Wang, Chang-Yun

    2016-04-01

    Marine organisms often protect themselves against their predators by chemical defensive strategy. The second metabolites isolated from marine organisms and their symbiotic microbes have been proven to play a vital role in marine chemical ecology, such as ichthyotoxicity, allelopathy, and antifouling. It is well known that the microscale models for marine chemoecology assessment are urgently needed for trace quantity of marine natural products. Zebrafish model has been widely used as a microscale model in the fields of environment ecological evaluation and drug safety evaluation, but seldom reported for marine chemoecology assessment. In this work, zebrafish embryo toxicity microscale model was established for ichthyotoxicity evaluation of marine natural products by using 24-well microplate based on zebrafish embryo. Ichthyotoxicity was evaluated by observation of multiple toxicological endpoints, including coagulation egg, death, abnormal heartbeat, no spontaneous movement, delayed hatch, and malformation of the different organs during zebrafish embryogenesis periods at 24, 48, and 72 h post-fertilization (hpf). 3,4-Dichloroaniline was used as the positive control for method validation. Subsequently, the established model was applied to test the ichthyotoxic activity of the compounds isolated from corals and their symbiotic microbes and to isolate the bioactive secondary metabolites from the gorgonian Subergorgia mollis under bioassay guidance. It was suggested that zebrafish embryo toxicity microscale model is suitable for bioassay-guided isolation and preliminary bioactivity screening of marine natural products.

  1. An improved model for natural convection heat loss from modified cavity receiver of solar dish concentrator

    SciTech Connect

    Reddy, K.S.; Sendhil Kumar, N.

    2009-10-15

    A 2-D model has been proposed to investigate the approximate estimation of the natural convection heat loss from modified cavity receiver of without insulation (WOI) and with insulation (WI) at the bottom of the aperture plane in our previous article. In this paper, a 3-D numerical model is presented to investigate the accurate estimation of natural convection heat loss from modified cavity receiver (WOI) of fuzzy focal solar dish concentrator. A comparison of 2-D and 3-D natural convection heat loss from a modified cavity receiver is carried out. A parametric study is carried out to develop separate Nusselt number correlations for 2-D and 3-D geometries of modified cavity receiver for estimation of convective heat loss from the receiver. The results show that the 2-D and 3-D are comparable only at higher angle of inclinations (60 {<=} {beta} {<=} 90 ) of the receiver. The present 3-D numerical model is compared with other well known cavity receiver models. The 3-D model can be used for accurate estimation of heat losses from solar dish collector, when compared with other well known models. (author)

  2. The effect of thermodynamic data on computer model predictions of uranium speciation in natural water systems.

    PubMed

    Unsworth, Emily R; Jones, Phil; Hill, Steve J

    2002-08-01

    Computer models have found widespread application in order to help elucidate and predict changes in environmental systems. One such application is the prediction of trace metal speciation in aqueous systems. This is achieved by solving a set of non-linear equations involving equilibrium constants for all the components in the system, within mass and charge balance constraints. In this study a comparison of the predicted uranium speciation from two computer programs, WHAM and PHREEQCI, is used to illustrate the effect variations in thermodynamic data can have on the models produced. Using the original thermodynamic data provided with the models, WHAM predicted the UO2(2+) ion as the major species (84%) while PHREEQCI predicted UO2(HPO4)2(2-) as the major species (86%). Substituting uranium data from the Nuclear Energy Agency Thermochemical Database project (NEA-TDB) into both programs produced similar results from each program, with UO2F+ predicted to dominate (68%) in a groundwater sample. Natural water samples often contain humic substances. The possible interaction of such substances with uranium was also modelled. The WHAM program includes a discreet site electrostatic humic substance model, however in order to use the PHREEQCI program to model humic substance interactions, a 'model fulvic acid' dataset was added to the program. These models predicted 85 to 98% uranium-humic substance species at neutral pH. This indicates that humic substances do need to be taken into account when modelling uranium speciation in natural water samples.

  3. Soft Mixer Assignment in a Hierarchical Generative Model of Natural Scene Statistics

    PubMed Central

    Schwartz, Odelia; Sejnowski, Terrence J.; Dayan, Peter

    2010-01-01

    Gaussian scale mixture models offer a top-down description of signal generation that captures key bottom-up statistical characteristics of filter responses to images. However, the pattern of dependence among the filters for this class of models is prespecified. We propose a novel extension to the gaussian scale mixture model that learns the pattern of dependence from observed inputs and thereby induces a hierarchical representation of these inputs. Specifically, we propose that inputs are generated by gaussian variables (modeling local filter structure), multiplied by a mixer variable that is assigned probabilistically to each input from a set of possible mixers. We demonstrate inference of both components of the generative model, for synthesized data and for different classes of natural images, such as a generic ensemble and faces. For natural images, the mixer variable assignments show invariances resembling those of complex cells in visual cortex; the statistics of the gaussian components of the model are in accord with the outputs of divisive normalization models. We also show how our model helps interrelate a wide range of models of image statistics and cortical processing. PMID:16999575

  4. Modelling seasonal variations of natural radioactivity in soils: A case study in southern Italy

    NASA Astrophysics Data System (ADS)

    Guagliardi, Ilaria; Rovella, Natalia; Apollaro, Carmine; Bloise, Andrea; Rosa, Rosanna De; Scarciglia, Fabio; Buttafuoco, Gabriele

    2016-12-01

    The activity of natural radionuclides in soil has become an environmental concern for local public and national authorities because of the harmful effects of radiation exposure on human health. In this context, modelling and mapping the activity of natural radionuclides in soil is an important research topic. The study was aimed to model, in a spatial sense, the soil radioactivity in an urban and peri-urban soils area in southern Italy to analyse the seasonal influence on soil radioactivity. Measures of gamma radiation naturally emitted through the decay of radioactive isotopes (potassium, uranium and thorium) were analysed using a geostatistical approach to map the spatial distribution of soil radioactivity. The activity of three radionuclides was measured at 181 locations using a high-resolution ?-ray spectrometry. To take into account the influence of season, the measurements were carried out in summer and in winter. Activity data were analysed by using a geostatistical approach and zones of relatively high or low radioactivity were delineated. Among the main processes which influence natural radioactivity such as geology, geochemical, pedological, and ecological processes, results of this study showed a prominent control of radio-emission measurements by seasonal changes. Low natural radioactivity levels were measured in December associated with winter weather and moist soil conditions (due to high rainfall and low temperature), and higher activity values in July, when the soil was dry and no precipitations occurred.

  5. Integrated Spatial Modeling using Geoinformatics: A Prerequisite for Natural Resources Management

    NASA Astrophysics Data System (ADS)

    Katpatal, Y. B.

    2014-12-01

    Every natural system calls for complete visualization for its holistic and sustainable development. Many a times, especially in developing countries, the approaches deviate from this basic paradigm and results in ineffective management of the natural resources. This becomes more relevant in these countries which are witnessing heavy exodus of the rural population to urban areas increasing the pressures on the basic commodities. Spatial technologies which provide the opportunity to enhance the knowledge visualization of the policy makers and administrators which facilitates technical and scientific management of the resources. Increasing population has created negative impacts on the per capita availability of several resources, which has been well accepted in the statistical records of several developing countries. For instance, the per capita availability of water in India has decreased substantially in last decade and groundwater depletion is on the rise. There is hence a need of tool which helps in restoring the resource through visualization and evaluation temporally. Geological parameters play an important role in operation of several natural systems and earth sciences parameters may not be ignored. Spatial technologies enables application of 2D as well as 3D modeling taking into account variety of natural parameters related to diverse areas. The paper presents case studies where spatial technology has helped in not only understanding the natural systems but also providing solutions, especially in Indian context. The case studies relate to Groundwater Management, Watershed and Basin Management, Groundwater recharge, Environment sustainability using spatial technology. Key Words: Spatial model, Groundwater, Hydrogeology, Geoinformatics, Sustainable Development.

  6. Toxicity of natural tear substitutes in a fully defined culture model of human corneal epithelial cells.

    PubMed

    Geerling, G; Daniels, J T; Dart, J K; Cree, I A; Khaw, P T

    2001-04-01

    Serum and saliva have recently been advocated as natural tear substitutes for intractable aqueous-deficient dry eyes, but the effects of these fluids on corneal epithelium have not been well characterized. A laboratory study was performed in a defined test model to compare the toxicity of natural and pharmaceutical tear substitutes and to identify potentially toxic factors in natural tear substitutes, such as amylase, hypotonicity, and variations in preparation. Primary human corneal epithelial cells were cultured with defined keratinocyte serum-free medium. The cells were incubated with hypromellose (hydroxypropylmethylcellulose 0.3%) with and without benzalkonium chloride 0.01%, saliva with differing osmolalities, 100% serum, and 50% serum (1:1 vol/vol with chloramphenicol 0.5%) for varying times and concentrations. Toxicity was examined in four ways. Microvillous density was assessed with scanning electron microscopy. Cell membrane permeability and intracellular esterase activity were analyzed after staining with fluorescent calcein-AM/ethidium homodimer and cellular adenosine triphosphate (ATP) was quantified using a luciferin-luciferase-based assay. The toxicity ranking of the tear substitutes correlated in all assays. The ATP assay was the most sensitive, followed by ethidium cell permeability, and finally the esterase activity. Preserved hypromellose was more toxic than the unpreserved preparation. Among natural tear substitutes, natural saliva was most toxic. Isotonic saliva and 50% serum were of similar toxicity, and 100% serum was least toxic. Natural tear substitutes were-except for natural saliva-less toxic than unpreserved hypromellose. Hypotonicity, but not amylase, was the major toxic effect associated with saliva. The dilution of serum with chloramphenicol induced toxicity. This is the first toxicity study using human primary corneal epithelial cells cultured under fully defined conditions as an in vitro model. Cellular ATP is a sensitive parameter

  7. Recent Progress in Understanding Natural-Hazards-Generated TEC Perturbations: Measurements and Modeling Results

    NASA Astrophysics Data System (ADS)

    Komjathy, A.; Yang, Y. M.; Meng, X.; Verkhoglyadova, O. P.; Mannucci, A. J.; Langley, R. B.

    2015-12-01

    Natural hazards, including earthquakes, volcanic eruptions, and tsunamis, have been significant threats to humans throughout recorded history. The Global Positioning System satellites have become primary sensors to measure signatures associated with such natural hazards. These signatures typically include GPS-derived seismic deformation measurements, co-seismic vertical displacements, and real-time GPS-derived ocean buoy positioning estimates. Another way to use GPS observables is to compute the ionospheric total electron content (TEC) to measure and monitor post-seismic ionospheric disturbances caused by earthquakes, volcanic eruptions, and tsunamis. Research at the University of New Brunswick (UNB) laid the foundations to model the three-dimensional ionosphere at NASA's Jet Propulsion Laboratory by ingesting ground- and space-based GPS measurements into the state-of-the-art Global Assimilative Ionosphere Modeling (GAIM) software. As an outcome of the UNB and NASA research, new and innovative GPS applications have been invented including the use of ionospheric measurements to detect tiny fluctuations in the GPS signals between the spacecraft and GPS receivers caused by natural hazards occurring on or near the Earth's surface.We will show examples for early detection of natural hazards generated ionospheric signatures using ground-based and space-borne GPS receivers. We will also discuss recent results from the U.S. Real-time Earthquake Analysis for Disaster Mitigation Network (READI) exercises utilizing our algorithms. By studying the propagation properties of ionospheric perturbations generated by natural hazards along with applying sophisticated first-principles physics-based modeling, we are on track to develop new technologies that can potentially save human lives and minimize property damage. It is also expected that ionospheric monitoring of TEC perturbations might become an integral part of existing natural hazards warning systems.

  8. Naturalness and a light Z'

    NASA Astrophysics Data System (ADS)

    Zhu, Bin; Staub, Florian; Ding, Ran

    2017-08-01

    Models with a light, additional gauge boson are attractive extensions of the standard model. Often these models are only considered as an effective low-energy theory without any assumption about an UV completion. This not only leaves the hierarchy problem of the SM unsolved, but also introduces a copy of it because of the new fundamental scalars responsible for breaking the new gauge group. A possible solution is to embed these models into a supersymmetric framework. However, this gives rise to an additional source of fine-tuning compared to the MSSM and poses a question about how natural such a setup is. One might expect that the additional fine-tuning is huge, namely, O (MSUSY2/mZ'2). In this paper, we point out that this is not necessarily the case. We show that it is possible to find a focus point behavior also in the new sector in coexistence with the MSSM focus point. We call this the "double focus point supersymmetry." Moreover, we stress the need for a proper inclusion of radiative corrections in the fine-tuning calculation: a tree-level estimate would lead to predictions for the tuning which can be wrong by many orders of magnitude. As a showcase, we use the U (1 )B -L extended MSSM and discuss possible consequences of the observed 8Be anomaly. However, similar features are expected for other models with an extended gauge group which involve potentially large Yukawa-like interactions of the new scalars.

  9. Model of continual metabolism species for estimating stability of CELSS and natural ecosystems

    NASA Astrophysics Data System (ADS)

    Bartsev, S. I.

    Estimation of stability range of natural and man-made ecosystems is necessary for effective control of them However traditional ecological models usually underestimate stability of real ecosystems It takes place due to the usage of fixed stoichiometry model of metabolism The objective is in creating theoretical and mathematical models for adequate description of both man-made and natural ecological systems A concept of genetically fixed but metabolically flexible species is considered in the paper According to the concept the total flow of matter through ecological system is supported at almost constant level depending on energy income by flexibility of metabolic organization of genetic species It is shown introducing continual metabolism species extends the range of stability making its estimation more adequate to real ecological systems

  10. Breathing and brain state: urethane anesthesia as a model for natural sleep.

    PubMed

    Pagliardini, Silvia; Funk, Gregory D; Dickson, Clayton T

    2013-09-15

    Respiratory control differs dramatically across sleep stages. Indeed, along with rapid eye movements (REM), respiration was one of the first physiological variables shown to be modulated across sleep stages. The study of sleep stages, their physiological correlates, and neurobiological underpinnings present a challenge because of the fragility and unpredictability of individual stages, not to mention sleep itself. Although anesthesia has often substituted as a model for a unitary stage of slow-wave (non-REM) sleep, it is only recently that urethane anesthesia has been proposed to model the full spectrum of sleep given the presence of spontaneous brain state alternations and concurrent physiological correlates that appear remarkably similar to natural sleep. We describe this model, its parallels with natural sleep, and its power for studying modulation of respiration. Specifically, we report data on the EEG characteristics across brain states under urethane anesthesia, the dependence of brain alternations on neurotransmitter systems, and the observations on state dependent modulation of respiration.

  11. Kainic Acid-Induced Excitotoxicity Experimental Model: Protective Merits of Natural Products and Plant Extracts

    PubMed Central

    Mohd Sairazi, Nur Shafika; Sirajudeen, K. N. S.; Asari, Mohd Asnizam; Muzaimi, Mustapha; Mummedy, Swamy; Sulaiman, Siti Amrah

    2015-01-01

    Excitotoxicity is well recognized as a major pathological process of neuronal death in neurodegenerative diseases involving the central nervous system (CNS). In the animal models of neurodegeneration, excitotoxicity is commonly induced experimentally by chemical convulsants, particularly kainic acid (KA). KA-induced excitotoxicity in rodent models has been shown to result in seizures, behavioral changes, oxidative stress, glial activation, inflammatory mediator production, endoplasmic reticulum stress, mitochondrial dysfunction, and selective neurodegeneration in the brain upon KA administration. Recently, there is an emerging trend to search for natural sources to combat against excitotoxicity-associated neurodegenerative diseases. Natural products and plant extracts had attracted a considerable amount of attention because of their reported beneficial effects on the CNS, particularly their neuroprotective effect against excitotoxicity. They provide significant reduction and/or protection against the development and progression of acute and chronic neurodegeneration. This indicates that natural products and plants extracts may be useful in protecting against excitotoxicity-associated neurodegeneration. Thus, targeting of multiple pathways simultaneously may be the strategy to maximize the neuroprotection effect. This review summarizes the mechanisms involved in KA-induced excitotoxicity and attempts to collate the various researches related to the protective effect of natural products and plant extracts in the KA model of neurodegeneration. PMID:26793262

  12. Large tensor spectrum of BICEP2 in the natural supersymmetric hybrid model

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Young; Kyae, Bumseok

    2014-07-01

    The large tensor spectrum recently observed by the BICEP2 Collaboration requires a super-Planckian field variation of the inflaton in the single-field inflationary scenario. The required slow-roll parameter ɛ ≈0.01 would restrict the e-folding number to around 7 in (sub-)Planckian inflationary models. To overcome such problems, we consider a two-field scenario based on the natural assisted supersymmetric (SUSY) hybrid model {"natural SUSY hybrid inflation" [K.-Y. Choi and B. Kyae, Phys. Lett. B 706, 243 (2012)]}, which combines the SUSY hybrid and the natural inflation models. The axionic inflaton field from the natural inflation sector can admit the right values for the tensor spectrum as well as a spectral index of 0.96 with a decay constant smaller than the Planck scale, f ≲MP. On the other hand, the vacuum energy of 2×1016 GeV with 50 e-folds is provided by the inflaton coming from the SUSY hybrid sector, avoiding the eta problem. These are achieved by introducing both the U(1)R and a shift symmetry, and employing the minimal Kähler potential.

  13. Short-term airing by natural ventilation - modeling and control strategies.

    PubMed

    Perino, M; Heiselberg, P

    2009-10-01

    The need to improve the energy efficiency of buildings requires new and more efficient ventilation systems. It has been demonstrated that innovative operating concepts that make use of natural ventilation seem to be more appreciated by occupants. This kind of system frequently integrates traditional mechanical ventilation components with natural ventilation devices, such as motorized windows and louvers. Among the various ventilation strategies that are currently available, buoyancy driven single-sided natural ventilation has proved to be very effective and can provide high air change rates for temperature and IAQ control. However, in order to promote a wider applications of these systems, an improvement in the knowledge of their working principles and the availability of new design and simulation tools is necessary. In this context, the paper analyses and presents the results of a research that was aimed at developing and validating numerical models for the analysis of buoyancy driven single-sided natural ventilation systems. Once validated, these models can be used to optimize control strategies in order to achieve satisfactory indoor comfort conditions and IAQ. Practical Implications Numerical and experimental analyses have proved that short-term airing by intermittent ventilation is an effective measure to satisfactorily control IAQ. Different control strategies have been investigated to optimize the capabilities of the systems. The proposed zonal model has provided good performances and could be adopted as a design tool, while CFD simulations can be profitably used for detailed studies of the pollutant concentration distribution in a room and to address local discomfort problems.

  14. Modeling of strontium sorption and speciation in a natural sediment-groundwater system

    NASA Astrophysics Data System (ADS)

    Koss, V.; Kim, J. I.

    1990-10-01

    The sorption of Sr in 21 natural sediment-groundwater systems from Gorleben, F.R.G., has been modeled using a simple surface complexation model. An apparent constant of Sr sorption has been computed taking into account bulk cation-exchange capacity of the sediment, the analytical composition of groundwater and experimental sorption data obtained from related systems. The method of determining the prevailing surface complex has been described in detail, using changing properties of the natural systems. Apparent sorption constants of natural groundwater components — Ca 2+, Mg 2+, K + and Na + — have been estimated. Competition from natural groundwater components for sorption sites has been taken into account. The main parameters governing Sr 2+ sorption are cation-exchange capacity of the sediment and ionic strength of the groundwater. The model describes the influence of experimental volume to mass ratio and of Sr 2+ concentration on sorption and allows one to compare the varying sorption data of similar systems. Computations were performed using the geochemical code MINEQL.

  15. DEVELOPMENT OF RESERVOIR CHARACTERIZATION TECHNIQUES AND PRODUCTION MODELS FOR EXPLOITING NATURALLY FRACTURED RESERVOIRS

    SciTech Connect

    Michael L. Wiggins; Raymon L. Brown; Faruk Civan; Richard G. Hughes

    2002-12-31

    For many years, geoscientists and engineers have undertaken research to characterize naturally fractured reservoirs. Geoscientists have focused on understanding the process of fracturing and the subsequent measurement and description of fracture characteristics. Engineers have concentrated on the fluid flow behavior in the fracture-porous media system and the development of models to predict the hydrocarbon production from these complex systems. This research attempts to integrate these two complementary views to develop a quantitative reservoir characterization methodology and flow performance model for naturally fractured reservoirs. The research has focused on estimating naturally fractured reservoir properties from seismic data, predicting fracture characteristics from well logs, and developing a naturally fractured reservoir simulator. It is important to develop techniques that can be applied to estimate the important parameters in predicting the performance of naturally fractured reservoirs. This project proposes a method to relate seismic properties to the elastic compliance and permeability of the reservoir based upon a sugar cube model. In addition, methods are presented to use conventional well logs to estimate localized fracture information for reservoir characterization purposes. The ability to estimate fracture information from conventional well logs is very important in older wells where data are often limited. Finally, a desktop naturally fractured reservoir simulator has been developed for the purpose of predicting the performance of these complex reservoirs. The simulator incorporates vertical and horizontal wellbore models, methods to handle matrix to fracture fluid transfer, and fracture permeability tensors. This research project has developed methods to characterize and study the performance of naturally fractured reservoirs that integrate geoscience and engineering data. This is an important step in developing exploitation strategies for

  16. Analogue modelling of inclined, brittle-ductile transpression: Testing analytical models through natural shear zones (external Betics)

    NASA Astrophysics Data System (ADS)

    Barcos, L.; Díaz-Azpiroz, M.; Balanyá, J. C.; Expósito, I.; Jiménez-Bonilla, A.; Faccenna, C.

    2016-07-01

    The combination of analytical and analogue models gives new opportunities to better understand the kinematic parameters controlling the evolution of transpression zones. In this work, we carried out a set of analogue models using the kinematic parameters of transpressional deformation obtained by applying a general triclinic transpression analytical model to a tabular-shaped shear zone in the external Betic Chain (Torcal de Antequera massif). According to the results of the analytical model, we used two oblique convergence angles to reproduce the main structural and kinematic features of structural domains observed within the Torcal de Antequera massif (α = 15° for the outer domains and α = 30° for the inner domain). Two parallel inclined backstops (one fixed and the other mobile) reproduce the geometry of the shear zone walls of the natural case. Additionally, we applied digital particle image velocimetry (PIV) method to calculate the velocity field of the incremental deformation. Our results suggest that the spatial distribution of the main structures observed in the Torcal de Antequera massif reflects different modes of strain partitioning and strain localization between two domain types, which are related to the variation in the oblique convergence angle and the presence of steep planar velocity - and rheological - discontinuities (the shear zone walls in the natural case). In the 15° model, strain partitioning is simple and strain localization is high: a single narrow shear zone is developed close and parallel to the fixed backstop, bounded by strike-slip faults and internally deformed by R and P shears. In the 30° model, strain partitioning is strong, generating regularly spaced oblique-to-the backstops thrusts and strike-slip faults. At final stages of the 30° experiment, deformation affects the entire model box. Our results show that the application of analytical modelling to natural transpressive zones related to upper crustal deformation

  17. Do general circulation models underestimate the natural variability in the artic climate?

    SciTech Connect

    Battisti, D.S.; Bitz, C.M.; Moritz, R.E.

    1997-08-01

    The authors examine the natural variability of the arctic climate system simulated by two very different models: the Geophysical Fluid Dynamics Laboratory (GFDL) global climate model, and an area-averaged model of the arctic atmosphere-sea ice-upper-ocean system called the polar cap climate model, the PCCM. A 1000-yr integration of the PCCM is performed in which the model is driven by a prescribed, stochastic atmospheric energy flux convergence (D), which has spectral characteristics that are identical to the spectra of the observed D. The standard deviation of the yearly mean sea ice thickness from this model is 0.85 m; the mean sea ice thickness is 3.1 m. In contrast, the standard deviation of the yearly averaged sea ice thickness in the GFDL climate model is found to be about 6% of the climatological mean thickness and only 24% of that simulated by the PCCM. A series of experiments is presented to determine the cause of these disparate results. First, after changing the treatment of sea ice and snow albedo in the (standard) PCCM model to be identical thermodynamically to that in the GFDL model, the PCCM is driven with D from the GFDL control integration to demonstrate that the PCCM model produces an arctic climate similar to that of the GFDL model. Integrations of the PCCM are then examined in which the different prescriptions of the sea ice treatment (GFDL vs standard PCCM) and D (GFDL vs observed) are permutated. The authors present calculations that indicate the variability in the sea ice thickness is extremely sensitive to the spectrum of the atmospheric energy flux convergence. A conservative best estimate for the amplitude of the natural variability in the arctic sea ice volume is presented.The results suggest that most of the global climate models that have been used to evaluate climate change may also have artificially quiescent variability in the Arctic. 24 refs., 6 figs., 3 tabs.

  18. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Mebane, Christopher A.; Schmidt, Travis S.; Keller, William (Bill)

    2015-01-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation–Tox models. To illustrate potential applications of the approaches, the 3 accumulation–Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  19. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities.

    PubMed

    Balistrieri, Laurie S; Mebane, Christopher A; Schmidt, Travis S; Keller, Wendel Bill

    2015-04-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation-Tox models. To illustrate potential applications of the approaches, the 3 accumulation-Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  20. A Posteriori Comparison of Natural and Surgical Destabilization Models of Canine Osteoarthritis

    PubMed Central

    Pelletier, Jean-Pierre; d'Anjou, Marc-André; Blond, Laurent; Pelletier, Johanne-Martel; del Castillo, Jérôme R. E.

    2013-01-01

    For many years Canis familiaris, the domestic dog, has drawn particular interest as a model of osteoarthritis (OA). Here, we optimized the dog model of experimental OA induced by cranial cruciate ligament sectioning. The usefulness of noninvasive complementary outcome measures, such as gait analysis for the limb function and magnetic resonance imaging for structural changes, was demonstrated in this model. Relationships were established between the functional impairment and the severity of structural changes including the measurement of cartilage thinning. In the dog model of naturally occurring OA, excellent test-retest reliability was denoted for the measurement of the limb function. A criterion to identify clinically meaningful responders to therapy was determined for privately owned dogs undergoing clinical trials. In addition, the recording of accelerometer-based duration of locomotor activity showed strong and complementary agreement with the biomechanical limb function. The translation potential of these models to the human OA condition is underlined. A preclinical testing protocol which combines the dog model of experimental OA induced by cranial cruciate ligament transection and the Dog model of naturally occurring OA offers the opportunity to further investigate the structural and functional benefits of disease-modifying strategies. Ultimately, a better prediction of outcomes for human clinical trials would be brought. PMID:24288664

  1. Numerical study of natural convection characteristics of nanofluids in an enclosure using multiphase model

    NASA Astrophysics Data System (ADS)

    Chen, Yan-Jun; Wang, Ping-Yang; Liu, Zhen-Hua

    2016-11-01

    The natural convective heat transfer and flow characteristics of nanofluids in an enclosure are numerically simulated using the multiphase-flow model and single phase model respectively. The simulated results are compared with the experimental results from the published papers to investigate the applicability of these models for nanofluids from a macro standpoint. The effects of Rayleigh number, Grashof number and volume concentration of nanoparticles on the heat transfer and flow characteristics are investigated and discussed. Comparisons of the horizontal and vertical central dimensionless velocity profiles between nanofluid and water for various Grashof numbers are studied. In addition, both streamline contours and isotherms lines for different volume concentrations of nanofluids are analyzed as well. The study results show that a great deviation exists between the simulated result of the single phase model and the experimental data on the relation of Nusselt number and Rayleigh number, which indicates that the single phase model cannot reflect the heat transfer characteristic of nanofluid. While the simulated results using the multiphase-flow model show a good agreement with the experimental data of nanofluid, which means that the multiphase-flow model is more suitable for the numerical study of nanofluid. For the natural convection, the present study holds the point that using Grashof numbers as the benchmark would be more appropriate to describe the heat transfer characteristics of nanofluid. Moreover, the simulated results demonstrate that adding nanoparticles into the base fluid can enhance both the motion of fluid and convection in the enclosure significantly.

  2. Fractal modeling of natural fracture networks. Final report, June 1994--June 1995

    SciTech Connect

    Ferer, M.V.; Dean, B.H.; Mick, C.

    1996-04-01

    Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Fracture networks can be determined for outcrops, but there is little reason to believe that the network in the reservoir should be identical because of the differences in stresses and history. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little apriori information. Three rather different types of approaches have been used: (1) dual porosity simulations; (2) `stochastic` modeling of fracture networks, and (3) fractal modeling of fracture networks. Stochastic models which assume a variety of probability distributions of fracture characteristics have been used with some success in modeling fracture networks. The advantage of these stochastic models over the dual porosity simulations is that real fracture heterogeneities are included in the modeling process. In the sections provided in this paper the authors will present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using their fractal analysis over a stochastic analysis; (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  3. Models in physics teaching: an approach to highlight the nature of knowledge

    NASA Astrophysics Data System (ADS)

    Botelho Kneubil, Fabiana

    2016-11-01

    In this work we show an approach based on models, for an usual subject in an introductory physics course, in order to foster discussions on the nature of physical knowledge. The introduction of elements of the nature of knowledge in physics lessons has been emphasised by many educators and one uses the case of metals to show the theoretical and phenomenological dimensions of physics. The discussion is made by means of four questions whose answers cannot be reached neither for theoretical elements nor experimental measurements. Between these two dimensions it is necessary to realise a series of reasoning steps to deepen the comprehension of microscopic concepts, such as electrical resistivity, drift velocity and free electrons. When this approach is highlighted, beyond the physical content, aspects of its nature become explicit and may improve the structuring of knowledge for learners on this subject.

  4. A Hierarchical Statistical Model of Natural Images Explains Tuning Properties in V2.

    PubMed

    Hosoya, Haruo; Hyvärinen, Aapo

    2015-07-22

    Previous theoretical and experimental studies have demonstrated tight relationships between natural image statistics and neural representations in V1. In particular, receptive field properties similar to simple and complex cells have been shown to be inferable from sparse coding of natural images. However, whether such a relationship exists in higher areas has not been clarified. To address this question for V2, we trained a sparse coding model that took as input the output of a fixed V1-like model, which was in its turn fed a large variety of natural image patches as input. After the training, the model exhibited response properties that were qualitatively and quantitatively compatible with three major neurophysiological results on macaque V2, as follows: (1) homogeneous and heterogeneous integration of local orientations (Anzai et al., 2007); (2) a wide range of angle selectivities with biased sensitivities to one component orientation (Ito and Komatsu, 2004); and (3) exclusive length and width suppression (Schmid et al., 2014). The reproducibility was stable across variations in several model parameters. Further, a formal classification of the internal representations of the model units offered detailed interpretations of the experimental data, emphasizing that a novel type of model cell that could detect a combination of local orientations converging toward a single spatial point (potentially related to corner-like features) played an important role in reproducing tuning properties compatible with V2. These results are consistent with the idea that V2 uses a sparse code of natural images. Significance statement: Sparse coding theory has successfully explained a number of receptive field properties in V1; but how about in V2? This question has recently become important since a variety of properties distinct from V1 have been discovered in V2, and thus a more integrative understanding is called for. Our study shows that a hierarchical sparse coding model of

  5. Modeling aesthetics to support an ecosystem services approach for natural resource management decision making.

    PubMed

    Booth, Pieter N; Law, Sheryl A; Ma, Jane; Buonagurio, John; Boyd, James; Turnley, Jessica

    2017-09-01

    This paper reviews literature on aesthetics and describes the development of vista and landscape aesthetics models. Spatially explicit variables were chosen to represent physical characteristics of natural landscapes that are important to aesthetic preferences. A vista aesthetics model evaluates the aesthetics of natural landscapes viewed from distances of more than 1000 m, and a landscape aesthetics model evaluates the aesthetic value of wetlands and forests within 1000 m from the viewer. Each of the model variables is quantified using spatially explicit metrics on a pixel-specific basis within EcoAIM™, a geographic information system (GIS)-based ecosystem services (ES) decision analysis support tool. Pixel values are "binned" into ranked categories, and weights are assigned to select variables to represent stakeholder preferences. The final aesthetic score is the weighted sum of all variables and is assigned ranked values from 1 to 10. Ranked aesthetic values are displayed on maps by patch type and integrated within EcoAIM. The response of the aesthetic scoring in the models was tested by comparing current conditions in a discrete area of the facility with a Development scenario in the same area. The Development scenario consisted of two 6-story buildings and a trail replacing natural areas. The results of the vista aesthetic model indicate that the viewshed area variable had the greatest effect on the aesthetics overall score. Results from the landscape aesthetics model indicate a 10% increase in overall aesthetics value, attributed to the increase in landscape diversity. The models are sensitive to the weights assigned to certain variables by the user, and these weights should be set to reflect regional landscape characteristics as well as stakeholder preferences. This demonstration project shows that natural landscape aesthetics can be evaluated as part of a nonmonetary assessment of ES, and a scenario-building exercise provides end users with a tradeoff

  6. An analytical and experimental investigation of natural circulation transients in a model pressurized water reactor

    SciTech Connect

    Massoud, M

    1987-01-01

    Natural Circulation phenomena in a simulated PWR was investigated experimentally and analytically. The experimental investigation included determination of system characteristics as well as system response to the imposed transient under symmetric and asymmetric operations. System characteristics were used to obtain correlation for heat transfer coefficient in heat exchangers, system flow resistance, and system buoyancy heat. Asymmetric transients were imposed to study flow oscillation and possible instability. The analytical investigation encompassed development of mathematical model for single-phase, steady-state and transient natural circulation as well as modification of existing model for two-phase flow analysis of phenomena such as small break LOCA, high pressure coolant injection and pump coast down. The developed mathematical model for single-phase analysis was computer coded to simulate the imposed transients. The computer program, entitled ''Symmetric and Asymmetric Analysis of Single-Phase Flow (SAS),'' were employed to simulate the imposed transients. It closely emulated the system behavior throughout the transient and subsequent steady-state. Modifications for two-phase flow analysis included addition of models for once-through steam generator and electric heater rods. Both programs are faster than real time. Off-line, they can be used for prediction and training applications while on-line they serve for simulation and signal validation. The programs can also be used to determine the sensitivity of natural circulation behavior to variation of inputs such as secondary distribution and power transients.

  7. Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models.

    PubMed

    He, Zhangyi; Beaumont, Mark; Yu, Feng

    2017-07-05

    We explore the effect of different mechanisms of natural selection on the evolution of populations for one- and two-locus systems. We compare the effect of viability and fecundity selection in the context of the Wright-Fisher model with selection under the assumption of multiplicative fitness. We show that these two modes of natural selection correspond to different orderings of the processes of population regulation and natural selection in the Wright-Fisher model. We find that under the Wright-Fisher model these two different orderings can affect the distribution of trajectories of haplotype frequencies evolving with genetic recombination. However, the difference in the distribution of trajectories is only appreciable when the population is in significant linkage disequilibrium. We find that as linkage disequilibrium decays the trajectories for the two different models rapidly become indistinguishable. We discuss the significance of these findings in terms of biological examples of viability and fecundity selection, and speculate that the effect may be significant when factors such as gene migration maintain a degree of linkage disequilibrium. Copyright © 2017 He et al.

  8. Effects of the Ordering of Natural Selection and Population Regulation Mechanisms on Wright-Fisher Models

    PubMed Central

    He, Zhangyi; Beaumont, Mark; Yu, Feng

    2017-01-01

    We explore the effect of different mechanisms of natural selection on the evolution of populations for one- and two-locus systems. We compare the effect of viability and fecundity selection in the context of the Wright-Fisher model with selection under the assumption of multiplicative fitness. We show that these two modes of natural selection correspond to different orderings of the processes of population regulation and natural selection in the Wright-Fisher model. We find that under the Wright-Fisher model these two different orderings can affect the distribution of trajectories of haplotype frequencies evolving with genetic recombination. However, the difference in the distribution of trajectories is only appreciable when the population is in significant linkage disequilibrium. We find that as linkage disequilibrium decays the trajectories for the two different models rapidly become indistinguishable. We discuss the significance of these findings in terms of biological examples of viability and fecundity selection, and speculate that the effect may be significant when factors such as gene migration maintain a degree of linkage disequilibrium. PMID:28500051

  9. Efficiency of a mathematical model in generating CAD/CAM-partial crowns with natural tooth morphology.

    PubMed

    Ender, Andreas; Mörmann, Werner H; Mehl, Albert

    2011-04-01

    The "biogeneric tooth model" can be used for computer-aided design (CAD) of the occlusal surface of dental restorations. From digital 3D-data, it automatically retrieves a morphology matching the natural surface left after preparation. This study evaluates the potential of this method for generating well-matched and well-adjusted CAD/computer-aided manufacturing (CAM) fabricated partial crowns. Twelve models with partial crown preparations were mounted into an articulator. Partial crowns were designed with the Cerec 3D CAD software based on the biogeneric tooth model (Biog.CAD) and, for control, with a conventional data-based Cerec 3D CAD software (Conv.CAD). The design time was measured, and the naturalness of the morphology was visually assessed. The restorations were milled, cemented on the models, and the vertical discrepancy and the time for final occlusal adjustment were measured. The Biog.CAD software offered a significantly higher naturalness (up to 225 to 11 scores) and was significantly faster by 251 (± 78) s in designing partial crowns (p < 0.01) compared to Conv.CAD software. Vertical discrepancy, 0.52 (± 0.28) mm for Conv.CAD and 0.46 (± 0.19)mm for Biog.CAD, and occlusal adjustment time, 118 (± 132)s for Conv.CAD and 102 (± 77)s for Biog.CAD, did not differ significantly. In conclusion, the biogeneric tooth model is able to generate occlusal morphology of partial crowns in a fully automated process with higher naturalness compared to conventional interactive CAD software.

  10. Natural Non-Trasgenic Animal Models for Research in Alzheimer’s Disease

    PubMed Central

    Sarasa, Manuel; Pesini, Pedro

    2009-01-01

    The most common animal models currently used for Alzheimer disease (AD) research are transgenic mice that express a mutant form of human Aβ precursor protein (APP) and/or some of the enzymes implicated in their metabolic processing. However, these transgenic mice carry their own APP and APP-processing enzymes, which may interfere in the production of different amyloid-beta (Aβ) peptides encoded by the human transgenes. Additionally, the genetic backgrounds of the different transgenic mice are a possible confounding factor with regard to crucial aspects of AD that they may (or may not) reproduce. Thus, although the usefulness of transgenic mice is undisputed, we hypothesized that additional relevant information on the physiopathology of AD could be obtained from other natural non-transgenic models. We have analyzed the chick embryo and the dog, which may be better experimental models because their enzymatic machinery for processing APP is almost identical to that of humans. The chick embryo is extremely easy to access and manipulate. It could be an advantageous natural model in which to study the cell biology and developmental function of APP and a potential assay system for drugs that regulate APP processing. The dog suffers from an age-related syndrome of cognitive dysfunction that naturally reproduces key aspects of AD including Aβ cortical pathology, neuronal degeneration and learning and memory disabilities. However, dense core neuritic plaques and neurofibrillary tangles have not been consistently demonstrated in the dog. Thus, these species may be natural models with which to study the biology of AD, and could also serve as assay systems for Aβ-targeted drugs or new therapeutic strategies against this devastating disease. PMID:19355852

  11. Damage and the Gutenberg-Richter Law: from simple models to natural earthquake fault systems

    NASA Astrophysics Data System (ADS)

    Tiampo, K. F.; Klein, W.; Rundle, J. B.; Dominguez, R.; Serino, C.

    2010-12-01

    Natural earthquake fault systems are highly nonhomogeneous in space, where these inhomogeneities occur because the earth is made of a variety of materials which hold and dissipate stress differently. One way that the inhomogeneous nature of fault systems manifests itself is in the spatial patterns which emerge in seismicity graphs (Tiampo et al., 2002, 2007). Despite their inhomogeneous nature, real faults are often modeled as spatially homogeneous systems. One argument for this approach is that earthquake faults experience long range stress transfer, and if this range is longer than the length scales associated with the inhomogeneities of the system, the dynamics of the system may be unaffected by their presence. However, it is not clear that this is the case. In this work we study the scaling of an earthquake model that is a variation of the Olami-Feder-Christensen (OFC) model, in order to explore the effect of spatial inhomogeneities on earthquake-like systems when interaction ranges are long, but not necessarily longer than the distances associated with those inhomogeneities (Rundle and Jackson, 1977; Olami et al., 1988). For long ranges and without inhomogeneities, such models have been found to produce scaling similar to GR scaling found in real earthquake systems (Rundle and Klein, 1993). In the earthquake models discussed here, damage is distributed inhomogeneously throughout and the interaction ranges, while long, are not longer than all of the damage length scales. We find that the scaling depends not only on the amount of damage, but also on the spatial distribution of that damage. In addition, we study the behaviour of particular natural earthquake faults and the spatial and temporal variation of GR scaling in those systems, in order to compare them with various damage cases from the simulations.

  12. Application of surface complexation models to anion adsorption by natural materials.

    PubMed

    Goldberg, Sabine

    2014-10-01

    Various chemical models of ion adsorption are presented and discussed. Chemical models, such as surface complexation models, provide a molecular description of anion adsorption reactions using an equilibrium approach. Two such models, the constant capacitance model and the triple layer model, are described in the present study. Characteristics common to all the surface complexation models are equilibrium constant expressions, mass and charge balances, and surface activity coefficient electrostatic potential terms. Methods for determining parameter values for surface site density, capacitances, and surface complexation constants also are discussed. Spectroscopic experimental methods of establishing ion adsorption mechanisms include vibrational spectroscopy, nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, X-ray absorption spectroscopy, and X-ray reflectivity. Experimental determinations of point of zero charge shifts and ionic strength dependence of adsorption results and molecular modeling calculations also can be used to deduce adsorption mechanisms. Applications of the surface complexation models to heterogeneous natural materials, such as soils, using the component additivity and the generalized composite approaches are described. Emphasis is on the generalized composite approach for predicting anion adsorption by soils. Continuing research is needed to develop consistent and realistic protocols for describing ion adsorption reactions on soil minerals and soils. The availability of standardized model parameter databases for use in chemical speciation-transport models is critical. Published 2014 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and as such, is in the public domain in the in the United States of America.

  13. Review and perspectives: Understanding natural-hazards-generated ionospheric perturbations using GPS measurements and coupled modeling

    NASA Astrophysics Data System (ADS)

    Komjathy, Attila; Yang, Yu-Ming; Meng, Xing; Verkhoglyadova, Olga; Mannucci, Anthony J.; Langley, Richard B.

    2016-07-01

    Natural hazards including earthquakes, volcanic eruptions, and tsunamis have been significant threats to humans throughout recorded history. Global navigation satellite systems (GNSS; including the Global Positioning System (GPS)) receivers have become primary sensors to measure signatures associated with natural hazards. These signatures typically include GPS-derived seismic deformation measurements, coseismic vertical displacements, and real-time GPS-derived ocean buoy positioning estimates. Another way to use GPS observables is to compute the ionospheric total electron content (TEC) to measure, model, and monitor postseismic ionospheric disturbances caused by, e.g., earthquakes, volcanic eruptions, and tsunamis. In this paper, we review research progress at the Jet Propulsion Laboratory and elsewhere using examples of ground-based and spaceborne observation of natural hazards that generated TEC perturbations. We present results for state-of-the-art imaging using ground-based and spaceborne ionospheric measurements and coupled atmosphere-ionosphere modeling of ionospheric TEC perturbations. We also report advancements and chart future directions in modeling and inversion techniques to estimate tsunami wave heights and ground surface displacements using TEC measurements and error estimates. Our initial retrievals strongly suggest that both ground-based and spaceborne GPS remote sensing techniques could play a critical role in detection and imaging of the upper atmosphere signatures of natural hazards including earthquakes and tsunamis. We found that combining ground-based and spaceborne measurements may be crucial in estimating critical geophysical parameters such as tsunami wave heights and ground surface displacements using TEC observations. The GNSS-based remote sensing of natural-hazard-induced ionospheric disturbances could be applied to and used in operational tsunami and earthquake early warning systems.

  14. Priming of plant resistance by natural compounds. Hexanoic acid as a model

    PubMed Central

    Aranega-Bou, Paz; de la O Leyva, Maria; Finiti, Ivan; García-Agustín, Pilar; González-Bosch, Carmen

    2014-01-01

    Some alternative control strategies of currently emerging plant diseases are based on the use of resistance inducers. This review highlights the recent advances made in the characterization of natural compounds that induce resistance by a priming mechanism. These include vitamins, chitosans, oligogalacturonides, volatile organic compounds, azelaic and pipecolic acid, among others. Overall, other than providing novel disease control strategies that meet environmental regulations, natural priming agents are valuable tools to help unravel the complex mechanisms underlying the induced resistance (IR) phenomenon. The data presented in this review reflect the novel contributions made from studying these natural plant inducers, with special emphasis placed on hexanoic acid (Hx), proposed herein as a model tool for this research field. Hx is a potent natural priming agent of proven efficiency in a wide range of host plants and pathogens. It can early activate broad-spectrum defenses by inducing callose deposition and the salicylic acid (SA) and jasmonic acid (JA) pathways. Later it can prime pathogen-specific responses according to the pathogen’s lifestyle. Interestingly, Hx primes redox-related genes to produce an anti-oxidant protective effect, which might be critical for limiting the infection of necrotrophs. Our Hx-IR findings also strongly suggest that it is an attractive tool for the molecular characterization of the plant alarmed state, with the added advantage of it being a natural compound. PMID:25324848

  15. Hierarchical model of natural images and the origin of scale invariance

    PubMed Central

    Saremi, Saeed; Sejnowski, Terrence J.

    2013-01-01

    The study of natural images and how our brain processes them has been an area of intense research in neuroscience, psychology, and computer science. We introduced a unique approach to studying natural images by decomposing images into a hierarchy of layers at different logarithmic intensity scales and mapping them to a quasi-2D magnet. The layers were in different phases: “cold” and ordered at large-intensity scales, “hot” and disordered at small-intensity scales, and going through a second-order phase transition at intermediate scales. There was a single “critical” layer in the hierarchy that exhibited long-range correlation similar to that found in the 2D Ising model of ferromagnetism at the critical temperature. We also determined the interactions between layers mapped from natural images and found mutual inhibition that generated locally “frustrated” antiferromagnetic states. Almost all information in natural images was concentrated in a few layers near the phase transition, which has biological implications and also points to the hierarchical origin of scale invariance in natural images. PMID:23382241

  16. Hierarchical model of natural images and the origin of scale invariance.

    PubMed

    Saremi, Saeed; Sejnowski, Terrence J

    2013-02-19

    The study of natural images and how our brain processes them has been an area of intense research in neuroscience, psychology, and computer science. We introduced a unique approach to studying natural images by decomposing images into a hierarchy of layers at different logarithmic intensity scales and mapping them to a quasi-2D magnet. The layers were in different phases: "cold" and ordered at large-intensity scales, "hot" and disordered at small-intensity scales, and going through a second-order phase transition at intermediate scales. There was a single "critical" layer in the hierarchy that exhibited long-range correlation similar to that found in the 2D Ising model of ferromagnetism at the critical temperature. We also determined the interactions between layers mapped from natural images and found mutual inhibition that generated locally "frustrated" antiferromagnetic states. Almost all information in natural images was concentrated in a few layers near the phase transition, which has biological implications and also points to the hierarchical origin of scale invariance in natural images.

  17. Natural addiction: a behavioral and circuit model based on sugar addiction in rats.

    PubMed

    Hoebel, Bartley G; Avena, Nicole M; Bocarsly, Miriam E; Rada, Pedro

    2009-03-01

    The distinction between natural addiction and drug addiction is interesting from many points of view, including scientific and medical perspectives. "Natural addictions" are those based on activation of a physiobehavioral system, such as the one that controls metabolism, foraging, and eating to achieve energy balance. "Drug addictions" activate many systems based on their pharmacology. This review discusses the following questions: (1) When does food produce a natural addiction? Sugar causes signs of addiction if the scheduling conditions are appropriate to cause binge eating. (2) Why does addictive-like behavior result? Bingeing on a 10% sucrose solution repeatedly releases dopamine in the nucleus accumbens, and it delays the release of acetylcholine, thereby postponing satiety. Opioid involvement is shown by withdrawal caused by naloxone or food deprivation. Bingeing, withdrawal, and abstinence-induced motivation are described as the basis for a vicious cycle leading to excessive eating. (3) Which foods can lead to natural addiction? A variety of sugars, saccharin, and sham feeding are compared with bingeing on high-fat diets, which seem to lack sugar's opioid-withdrawal characteristic. (4) How does natural food addiction relate to obesity? Low basal dopamine may be a common factor, leading to "eating for dopamine." (5) In a neural model, the accumbens is depicted as having separate GABA output pathways for approach and avoidance, both controlled by dopamine and acetylcholine. These outputs, in turn, control lateral hypothalamic glutamate release, which starts a meal, and GABA release, which stops it.

  18. The Ti environment in natural hibonite: XANES spectroscopy and computer modelling

    NASA Astrophysics Data System (ADS)

    Kravtsova, Antonina N.; Soldatov, Alexander V.; Walker, Andrew M.; Berry, Andrew J.

    2016-05-01

    The local atomic structure around Ti in Ti-bearing hibonite (CaAl12O19) was studied using X-ray absorption near-edge structure (XANES) spectroscopy and computer modelling. Structural models of the direct substitution of Al by Ti3+, Al by Ti4+ charge balanced by the coupled substitution of Mg2+ for Al, and small Ti clusters were considered. The Ti K-XANES spectra of natural hibonite with different Ti concentration were recorded. Theoretical Ti K- XANES spectra for structural models of hibonite were calculated. It was shown that the theoretical Ti K-XANES spectra for a model with Ti at the five-coordinated M2 site are in agreement with the experimental XANES spectra of hibonite with low concentrations of Ti, while the theoretical spectra for a structural model of clustered Ti are in agreement with the experimental spectra of hibonite with higher Ti contents.

  19. Phenylalanine ab initio models for the simulation of skin natural moisturizing factor

    NASA Astrophysics Data System (ADS)

    Carvalho, B. G.; Raniero, L. J.; Martin, A. A.; Favero, P. P.

    2013-04-01

    In this study, we evaluated models that can be used to simulate amino acids in biological environments via density functional theory (DFT). The goal was to obtain realistic representations that combine computational economy and result quality when compared to experimental data. We increased the complexity of the models by using a model of an amino acid in a vacuum, followed by a water-solvated amino acid model. To consider pH variation, we simulated zwitterionic and nonionic amino acid configurations. The amino acid chosen for testing was phenylalanine, an aromatic amino acid present in high concentrations in the natural moisturizing factor of skin that plays a fundamental role in ultraviolet protection and vitiligo disease. To validate the models, vibrational modes and electronic properties were calculated and compared to experimental results.

  20. Comparison of Color Model in Cotton Image Under Conditions of Natural Light

    NASA Astrophysics Data System (ADS)

    Zhang, J. H.; Kong, F. T.; Wu, J. Z.; Wang, S. W.; Liu, J. J.; Zhao, P.

    Although the color images contain a large amount of information reflecting the species characteristics, different color models also get different information. The selection of color models is the key to separating crops from background effectively and rapidly. Taking the cotton images collected under natural light as the object, we convert the color components of RGB color model, HSL color model and YIQ color model respectively. Then, we use subjective evaluation and objective evaluation methods, evaluating the 9 color components of conversion. It is concluded that the Q component of the soil, straw and plastic film region gray values remain the same without larger fluctuation when using subjective evaluation method. In the objective evaluation, we use the variance method, average gradient method, gray prediction objective evaluation error statistics method and information entropy method respectively to find the minimum numerical of Q color component suitable for background segmentation.

  1. The human model: a genetic dissection of immunity to infection in natural conditions.

    PubMed

    Casanova, Jean-Laurent; Abel, Laurent

    2004-01-01

    Tremendous progress has been achieved in developmental, cellular and molecular immunology in the past 20 years, largely due to studies using the mouse as a model system and the arrival of molecular genetics. Immunology is now faced with a difficult challenge. What are the functions of the individual cells and molecules in achieving immunity to infection? Renewed interest in animal models of disease has provided considerable insight in this area, but such models of infection suffer from the inherent limitation of being experimental. In humans, the complex host-environment interaction occurs in natural, as opposed to experimental, conditions. The human model is therefore an indispensable complement to animal models, as it allows an observational genetic dissection of immunity to infection.

  2. Evaluation of Northern Hemisphere natural climate variability in multiple temperature reconstructions and global climate model simulations

    NASA Astrophysics Data System (ADS)

    Bell, J. L.; Sloan, L. C.; Revenaugh, J.; Duffy, P. B.

    2003-06-01

    The detection of anthropogenic climate change in observations and the validation of climate models both rely on understanding natural climate variability. To evaluate internal climate variability, we apply spectral analysis to time series of surface air temperature (SAT) from nine coupled general circulation model (GCM) simulations, three recent global paleotemperature reconstructions, and Northern Hemisphere (NH) instrumental records. Our comparison is focused on the NH due to the greater spatial and temporal coverage and validation of the available NH temperature reconstructions. The paleotemperature reconstructions capture the general magnitude of NH climate variability, but not the precise variance and specific spatial, temporal, or periodic signals demonstrated in the instrumental record. The models achieved varying degrees of success for each measure of variability analyzed, with none of the models consistently capturing the appropriate variability. In general, the models performed best in the analysis of combined mean annual land and marine variability.

  3. A regional GIS-based model for reconstructing natural monthly streamflow series at ungauged sites

    NASA Astrophysics Data System (ADS)

    Pumo, Dario; Lo Conti, Francesco; Viola, Francesco; Noto, Leonardo V.

    2016-04-01

    Several hydrologic applications require reliable estimates of monthly runoff in river basins to face the widespread lack of data, both in time and in space. The main aim of this work is to propose a regional model for the estimation of monthly natural runoff series at ungauged sites, analyzing its applicability, reliability and limitations. A GIS (Geographic Information System) based model is here developed and applied to the entire region of Sicily (Italy). The core of this tool is a regional model for the estimation of monthly natural runoff series, based on a simple modelling structure, consisting of a regression based rainfall-runoff model with only four parameters. The monthly runoff is obtained as a function of precipitation and mean temperature at the same month and runoff at the previous month. For a given basin, the four model parameters are assessed by specific regional equations as a function of some easily measurable geomorphic and climate basins' descriptors. The model is calibrated by a "two-step" procedure applied to a number of gauged basins over the region. The first step is aimed at the identification of a set of parameters optimizing model performances at the level of single basin. Such "optimal" parameters sets, derived for each calibration basin, are successively used inside a regional regression analysis, performed at the second step, by which the regional equations for model parameters assessment are defined and calibrated. All the gauged watersheds across the Sicily have been analyzed, selecting 53 basins for model calibration and using other 6 basins exclusively for validation purposes. Model performances, quantitatively evaluated considering different statistical indexes, demonstrate a relevant model ability in capturing the observed hydrological response at both the monthly level and higher time scales (seasonal and annual). One of the key features related to the proposed methodology is its easy transferability to other arid and semiarid

  4. Development of Antiatherosclerotic Drugs on the basis of Natural Products Using Cell Model Approach

    PubMed Central

    Orekhov, Alexander N.; Sobenin, Igor A.; Revin, Victor V.; Bobryshev, Yuri V.

    2015-01-01

    Atherosclerosis including its subclinical form is one of the key medical and social problems. At present, there is no therapy available for widespread use against subclinical atherosclerosis. The use of synthetic drugs for the prevention of arteriosclerosis in its early stages is not sufficient because of the limited indications for severe side effects and high cost of treatment. Obviously, effective antiatherosclerotic drugs based on natural products would be a preferred alternative. Simple cell-based models for testing different natural products have been developed and the ability of natural products to prevent intracellular lipid accumulation in primary cell culture was evaluated. This approach utilizing cell models allowed to test effects of such direct antiatherosclerotic therapy, analyzing the effects mimicking those which can occur “at the level” of arterial wall via the inhibition of intracellular lipid deposition. The data from the carried out clinical trials support a point of view that the identification of antiatherosclerotic activity of natural products might offer a great opportunity for the prevention and treatment of atherosclerotic disease, reducing cardiovascular morbidity and mortality. PMID:26347804

  5. Study of natural circulation in a VHTR after a LOFA using different turbulence models

    SciTech Connect

    Yu-Hsin Tung; Yuh-Ming Ferng; Richard W. Johnson; Ching-Chang Chieng

    2013-10-01

    Natural convection currents in the core are anticipated in the event of the failure of the gas circulator in a prismatic gas-cooled very high temperature reactor (VHTR). The paths that the helium coolant takes in forming natural circulation loops and the effective heat transport are of interest. The heated flow in the reactor core is turbulent during normal operating conditions and at the beginning of the LOFA with forced convection, but the flow may significantly be slowed down after the event and laminarized with mixed convection. In the present study, the potential occurrence and effective heat transport of natural circulation are demonstrated using computational fluid dynamic (CFD) calculations with different turbulence models as well as laminar flow. Validations and recommendation on turbulence model selection are conducted. The study concludes that large loop natural convection is formed due to the enhanced turbulence levels by the buoyancy effect and the turbulent regime near the interface of upper plenum and flow channels increases the flow resistance for channel flows entering upper plenum and thus less heat can be removed from the core than the prediction by laminar flow assumption.

  6. Quantifying natural delta variability using a multiple-point geostatistics prior uncertainty model

    NASA Astrophysics Data System (ADS)

    Scheidt, Céline; Fernandes, Anjali M.; Paola, Chris; Caers, Jef

    2016-10-01

    We address the question of quantifying uncertainty associated with autogenic pattern variability in a channelized transport system by means of a modern geostatistical method. This question has considerable relevance for practical subsurface applications as well, particularly those related to uncertainty quantification relying on Bayesian approaches. Specifically, we show how the autogenic variability in a laboratory experiment can be represented and reproduced by a multiple-point geostatistical prior uncertainty model. The latter geostatistical method requires selection of a limited set of training images from which a possibly infinite set of geostatistical model realizations, mimicking the training image patterns, can be generated. To that end, we investigate two methods to determine how many training images and what training images should be provided to reproduce natural autogenic variability. The first method relies on distance-based clustering of overhead snapshots of the experiment; the second method relies on a rate of change quantification by means of a computer vision algorithm termed the demon algorithm. We show quantitatively that with either training image selection method, we can statistically reproduce the natural variability of the delta formed in the experiment. In addition, we study the nature of the patterns represented in the set of training images as a representation of the "eigenpatterns" of the natural system. The eigenpattern in the training image sets display patterns consistent with previous physical interpretations of the fundamental modes of this type of delta system: a highly channelized, incisional mode; a poorly channelized, depositional mode; and an intermediate mode between the two.

  7. Understanding the nature of science through the historical development of conceptual models

    NASA Astrophysics Data System (ADS)

    Metz, Donald J.

    Understanding the nature of science has been a common goal in science education for years and continues to hold a distinct place in the recently developed Pan-Canadian science framework. Although the nature of science is often prominent in the front end of such reform documents, the implementation of these goals is presumed to be taught implicitly with the delivery of knowledge outcomes. Research strongly indicates that most students have naive conceptions about the nature of science. Surprisingly, research also clearly shows that science teachers do not fare much better, and that when they do possess adequate understanding of the nature of science it does not significantly influence their behaviour in the classroom. Norm Lederman (1998), one of the leading scholars in this field, describes two approaches advocated by curriculum reform documents to address the nature of science outcomes. The first approach suggests that students can achieve nature of science outcomes by "doing science", the second suggests that history of science can enhance students' understanding of the nature of science. While Lederman advocates the use of the history of science, he argues that these approaches are not effective when used implicitly. He recommends that an explicit approach be used (planned for, taught, assessed), but so far there have been no studies which employ this technique beyond short lessons or limited case histories. This thesis advocates an explicit approach to teaching the nature of science using the historical development of conceptual models. The research study of this thesis integrated the historical development of conceptual models with the traditional content found in a typical grade ten chemistry curriculum. Participants in the research were 74 senior 2 (grade 10) science students from four different classes in three different schools in the province of Manitoba. Prior to, and after instruction, students wrote Lederman's VNOS nature of science test. The tests

  8. Assessment of MELCOR condensation models with the presence of noncondensable gas in natural convection flow regime

    DOE PAGES

    Yoon, Dhongik S; Jo, HangJin; Corradini, Michael L

    2017-04-01

    Condensation of steam vapor is an important mode of energy removal from the reactor containment. The presence of noncondensable gas complicates the process and makes it difficult to model. MELCOR, one of the more widely used system codes for containment analyses, uses the heat and mass transfer analogy to model condensation heat transfer. To investigate previously reported nodalization-dependence in natural convection flow regime, MELCOR condensation model as well as other models are studied. The nodalization-dependence issue is resolved by using physical length from the actual geometry rather than node size of each control volume as the characteristic length scale formore » MELCOR containment analyses. At the transition to turbulent natural convection regime, the McAdams correlation for convective heat transfer produces a better prediction compared to the original MELCOR model. The McAdams correlation is implemented in MELCOR and the prediction is validated against a set of experiments on a scaled AP600 containment. The MELCOR with our implemented model produces improved predictions. For steam molar fractions in the gas mixture greater than about 0.58, the predictions are within the uncertainty margin of the measurements. The simulation results still underestimate the heat transfer from the gas-steam mixture, implying that conservative predictions are provided.« less

  9. Models of Drug-induced Liver Injury for Evaluation of Phytotherapeutics and Other Natural Products

    PubMed Central

    Jaeschke, Hartmut; Williams, C. David; McGill, Mitchell R.; Xie, Yuchao; Ramachandran, Anup

    2013-01-01

    Extracts from medicinal plants, many of which have been used for centuries, are increasingly tested in models of hepatotoxicity. One of the most popular models to evaluate the hepatoprotective potential of natural products is acetaminophen (APAP)-induced liver injury, although other hepatotoxicity models such as carbon tetrachloride, thioacetamide, ethanol and endotoxin are occasionally used. APAP overdose is a clinically relevant model of drug-induced liver injury. Critical mechanisms and signaling pathways, which trigger necrotic cell death and sterile inflammation, are discussed. Although there is increasing understanding of the pathophysiology of APAP-induced liver injury, the mechanism is complex and prone to misinterpretation, especially when unknown chemicals such as plant extracts are tested. This review discusses the fundamental aspects that need to be considered when using this model, such as selection of the animal species or in vitro system, timing and dose-responses of signaling events, metabolic activation and protein adduct formation, the role of lipid peroxidation and apoptotic versus necrotic cell death, and the impact of the ensuing sterile inflammatory response. The goal is to enable researchers to select the appropriate model and experimental conditions for testing of natural products that will yield clinically relevant results and allow valid interpretations of the pharmacological mechanisms. PMID:23353004

  10. Moving on from Ramps? The Utility of the Social Model of Disability for Facilitating Experiences of Nature for Disabled Children

    ERIC Educational Resources Information Center

    Von Benzon, Nadia

    2010-01-01

    Experiences of nature have been shown to be beneficial for disabled children; however, opportunities for disabled children to experience nature are often limited. The social model of disability may provide a theoretical base for increasing access to nature for pupils at Special Educational Needs (SEN) schools. Using results from interviews…

  11. Moving on from Ramps? The Utility of the Social Model of Disability for Facilitating Experiences of Nature for Disabled Children

    ERIC Educational Resources Information Center

    Von Benzon, Nadia

    2010-01-01

    Experiences of nature have been shown to be beneficial for disabled children; however, opportunities for disabled children to experience nature are often limited. The social model of disability may provide a theoretical base for increasing access to nature for pupils at Special Educational Needs (SEN) schools. Using results from interviews…

  12. Zebrafish as a natural host model for Vibrio cholerae colonization and transmission.

    PubMed

    Runft, Donna L; Mitchell, Kristie C; Abuaita, Basel H; Allen, Jonathan P; Bajer, Sarah; Ginsburg, Kevin; Neely, Melody N; Withey, Jeffrey H

    2014-03-01

    The human diarrheal disease cholera is caused by the aquatic bacterium Vibrio cholerae. V. cholerae in the environment is associated with several varieties of aquatic life, including insect egg masses, shellfish, and vertebrate fish. Here we describe a novel animal model for V. cholerae, the zebrafish. Pandemic V. cholerae strains specifically colonize the zebrafish intestinal tract after exposure in water with no manipulation of the animal required. Colonization occurs in close contact with the intestinal epithelium and mimics colonization observed in mammals. Zebrafish that are colonized by V. cholerae transmit the bacteria to naive fish, which then become colonized. Striking differences in colonization between V. cholerae classical and El Tor biotypes were apparent. The zebrafish natural habitat in Asia heavily overlaps areas where cholera is endemic, suggesting that zebrafish and V. cholerae evolved in close contact with each other. Thus, the zebrafish provides a natural host model for the study of V. cholerae colonization, transmission, and environmental survival.

  13. Zebrafish as a Natural Host Model for Vibrio cholerae Colonization and Transmission

    PubMed Central

    Runft, Donna L.; Mitchell, Kristie C.; Abuaita, Basel H.; Allen, Jonathan P.; Bajer, Sarah; Ginsburg, Kevin; Neely, Melody N.

    2014-01-01

    The human diarrheal disease cholera is caused by the aquatic bacterium Vibrio cholerae. V. cholerae in the environment is associated with several varieties of aquatic life, including insect egg masses, shellfish, and vertebrate fish. Here we describe a novel animal model for V. cholerae, the zebrafish. Pandemic V. cholerae strains specifically colonize the zebrafish intestinal tract after exposure in water with no manipulation of the animal required. Colonization occurs in close contact with the intestinal epithelium and mimics colonization observed in mammals. Zebrafish that are colonized by V. cholerae transmit the bacteria to naive fish, which then become colonized. Striking differences in colonization between V. cholerae classical and El Tor biotypes were apparent. The zebrafish natural habitat in Asia heavily overlaps areas where cholera is endemic, suggesting that zebrafish and V. cholerae evolved in close contact with each other. Thus, the zebrafish provides a natural host model for the study of V. cholerae colonization, transmission, and environmental survival. PMID:24375135

  14. Proteomic identification of protease cleavage sites characterizes prime and non-prime specificity of cysteine cathepsins B, L, and S.

    PubMed

    Biniossek, Martin L; Nägler, Dorit K; Becker-Pauly, Christoph; Schilling, Oliver

    2011-12-02

    Cysteine cathepsins mediate proteome homeostasis and have pivotal functions in diseases such as cancer. To better understand substrate recognition by cathepsins B, L, and S, we applied proteomic identification of protease cleavage sites (PICS) for simultaneous profiling of prime and non-prime specificity. PICS profiling of cathepsin B endopeptidase specificity highlights strong selectivity for glycine in P3' due to an occluding loop blocking access to the primed subsites. In P1', cathepsin B has a partial preference for phenylalanine, which is not found for cathepsins L and S. Occurrence of P1' phenylalanine often coincides with aromatic residues in P2. For cathepsin L, PICS identifies 845 cleavage sites, representing the most comprehensive PICS profile to date. Cathepsin L specificity is dominated by the canonical preference for aromatic residues in P2 with limited contribution of prime-site selectivity determinants. Profiling of cathepsins B and L with a shorter incubation time (4 h instead of 16 h) did not reveal time-dependency of individual specificity determinants. Cathepsin S specificity was profiled at pH 6.0 and 7.5. The PICS profiles at both pH values display a high degree of similarity. Cathepsin S specificity is primarily guided by aliphatic residues in P2 with limited importance of prime-site residues.

  15. A simplified model of aerosol removal by natural processes in reactor containments

    SciTech Connect

    Powers, D.A.; Washington, K.E.; Sprung, J.L.; Burson, S.B.

    1996-07-01

    Simplified formulae are developed for estimating the aerosol decontamination that can be achieved by natural processes in the containments of pressurized water reactors and in the drywells of boiling water reactors under severe accident conditions. These simplified formulae were derived by correlation of results of Monte Carlo uncertainty analyses of detailed models of aerosol behavior under accident conditions. Monte Carlo uncertainty analyses of decontamination by natural aerosol processes are reported for 1,000, 2,000, 3,000, and 4,000 MW(th) pressurized water reactors and for 1,500, 2,500, and 3,500 MW(th) boiling water reactors. Uncertainty distributions for the decontamination factors and decontamination coefficients as functions of time were developed in the Monte Carlo analyses by considering uncertainties in aerosol processes, material properties, reactor geometry and severe accident progression. Phenomenological uncertainties examined in this work included uncertainties in aerosol coagulation by gravitational collision, Brownian diffusion, turbulent diffusion and turbulent inertia. Uncertainties in aerosol deposition by gravitational settling, thermophoresis, diffusiophoresis, and turbulent diffusion were examined. Electrostatic charging of aerosol particles in severe accidents is discussed. Such charging could affect both the coagulation and deposition of aerosol particles. Electrostatic effects are not considered in most available models of aerosol behavior during severe accidents and cause uncertainties in predicted natural decontamination processes that could not be taken in to account in this work. Median (50%), 90 and 10% values of the uncertainty distributions for effective decontamination coefficients were correlated with time and reactor thermal power. These correlations constitute a simplified model that can be used to estimate the decontamination by natural aerosol processes at 3 levels of conservatism. Applications of the model are described.

  16. Development of a natural Gas Systems Analysis Model (GSAM). Annual report

    SciTech Connect

    Not Available

    1994-02-01

    Lacking a detailed characterization of the resource base and a comprehensive borehole-to-burnertip evaluation model of the North American natural gas system, past R&D, tax and regulatory policies have been formulated without a full understanding of their likely direct and indirect impacts on future gas supply and demand. The recent disappearance of the deliverability surplus, pipeline deregulation, and current policy debates about regulatory initiatives in taxation, environmental compliance and leasing make the need for a comprehensive gas evaluation system critical. Traditional econometric or highly aggregated energy models are increasingly regarded as unable to incorporate available geologic detail and explicit technology performance and costing algorithms necessary to evaluate resource-technology-economic interactions in a market context. The objective of this research is to create a comprehensive, non-proprietary, microcomputer model of the North American natural gas system. GSAM explicitly evaluates the key components of the natural gas system, including resource base, exploration and development, extraction technology performance and costs, transportation and storage and end use. The primary focus is the detailed characterization of the resource base at the reservoir and sub-reservoir level and the impact of alternative extraction technologies on well productivity and economics. GSAM evaluates the complex interactions of current and alternative future technology and policy initiatives in the context of the evolving gas markets. Scheduled for completion in 1995, a prototype is planned for early 1994. ICF Resources reviewed relevant natural gas upstream, downstream and market models to identify appropriate analytic capabilities to incorporate into GSAM. We have reviewed extraction technologies to better characterize performance and costs in terms of GSAM parameters.

  17. Noninvasive Imaging of Natural Killer Cell-Mediated Apoptosis in a Mouse Tumor Model.

    PubMed

    Singh, Thoudam Debraj; Lee, Jaetae; Jeon, Yong Hyun

    2016-01-01

    Natural killer (NK) cells are cytotoxic lymphocytes that induce apoptosis in cancer cells infected with viruses and bacteria through a caspase-3-dependent pathway. Effective NK cell-based immunotherapy requires highly sensitive imaging tools for in vivo monitoring of the dynamic events involved in apoptosis. Here, we describe a noninvasive bioluminescence imaging approach to determine the antitumor effects of NK cell-based therapy by serial imaging of caspase-3-dependent apoptosis in a mouse model of human glioma.

  18. Focal species and landscape "naturalness" corridor models offer complementary approaches for connectivity conservation planning

    Treesearch

    Meade Krosby; Ian Breckheimer; D. John Pierce; Peter H. Singleton; Sonia A. Hall; Karl C. Halupka; William L. Gaines; Robert A. Long; Brad H. McRae; Brian L. Cosentino; Joanne P. Schuett-Hames

    2015-01-01

    Context   The dual threats of habitat fragmentation and climate change have led to a proliferation of approaches for connectivity conservation planning. Corridor analyses have traditionally taken a focal species approach, but the landscape ‘‘naturalness’’ approach of modeling connectivity among areas of low human modification has gained popularity...

  19. Semiorganic nonlinear optical material: Crystal growth, structure and optical properties of NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2}

    SciTech Connect

    Huang, Hongwei; Yao, Wenjiao; He, Ying; Tian, Na; Chen, Chuangtian; Zhang, Yihe

    2013-09-01

    Graphical abstract: - Highlights: • Semiorganic NLO material NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has been grown with sizes up to 8 × 5 × 2 mm{sup 3}. • It crystallizes in the noncentrosymmetric Monoclinic space group P2. • Thermal analysis demonstrated NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} are thermally stable up to 280. • NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has an absorption edge about 220 nm in the UV region. • It exhibits a NLO efficiency of about two times that of KDP (KH{sub 2}PO{sub 4}) standard. - Abstract: Single crystal of the semiorganic NLO material NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} has been grown with sizes up to 8 × 5 × 2 mm{sup 3} by the slow evaporation method. The crystal structure of this compound was determined by single crystal X-ray diffraction. It crystallizes in the Monoclinic space group P2 with lattice parameters a = 5.4045(11) Å, b = 11.692(2) Å, c = 9.4773(19) Å and Z = 2. Thermal analysis demonstrated NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} are thermally stable up to 280 °C. NaB(L-C{sub 4}H{sub 4}O{sub 5}){sub 2} exhibits an absorption edge about 220 nm in the UV region. The powder second-harmonic generation (SHG) measurement performed on the ground crystal indicates that it has a NLO efficiency of about 2 times that of KDP (KH{sub 2}PO{sub 4}) standard. In addition, the origin of stronger SHG effect was discussed.

  20. Statistics, models and learning in BCM theory of a natural visual environment

    NASA Astrophysics Data System (ADS)

    Lee, Ann Be-Su

    Recently, there has been a great deal of interest in the statistics of natural images from both biological and computational perspectives. From the biological side, it is widely believed that our visual system is adapted to deal efficiently with natural stimuli. Part of this adaptation is experience-dependent and occurs due to some general mechanism in the brain for modifying the synapses of a neuron as a function of the inputs to the neuron. A better understanding of natural scene statistics may thus provide insight into the role of the environment in the development of the nervous system. Two basis properties of natural images are: (i) they are extremely non-Gaussian, with highly kurtotic distributions for almost any mean-0 filter response, and (ii) their statistics seem to be largely invariant to a change of scale or coarse-graining. A detailed study of small patches of natural images shows that the state space of such patches is very sparse and highly structured, with most of the high-contrast data concentrated in low-dimensional manifolds and clusters. An important question in vision is whether we can find stochastic models that capture the typical structures of natural images. We argue that many of the observed characteristics of natural images are, at least partly, due to the world being made up of objects in some generalized sense. We develop a simplified visual environment where an image is formed from a set of elementary shapes, whose locations and scale are sampled from a homogeneous Poisson process. These shapes partially occlude one another as they are laid down in layers. The image model, although very simple, seems to capture much of the low-level statistics of naturally occurring scenes. We finally test whether the BCM theory of synaptic plasticity and inputs from this artificial visual environment can account for the observed response properties of cortical cells in the primary visual cortex. The study is an attempt to better understand what

  1. Modeling of natural acoustic frequencies of a gas-turbine plant combustion chamber

    NASA Astrophysics Data System (ADS)

    Zubrilin, I. A.; Gurakov, N. I.; Zubrilin, R. A.; Matveev, S. G.

    2017-05-01

    The paper presents results of determination of natural acoustic frequencies of a gas-turbine plant annular combustion chamber model using 3D-simulation. At the beginning, a calculation procedure for determining natural acoustic frequencies of the gas-turbine plant combustion chamber was worked out. The effect of spatial inhomogeneity of the flow parameters (fluid composition, pressure, temperature) arising in combustion and some geometrical parameters (cooling holes of the flame tube walls) on the calculation results is studied. It is found that the change of the fluid composition in combustion affects the acoustic velocity not more than 5%; therefore, the air with a volume variable temperature can be taken as a working fluid in the calculation of natural acoustic frequencies. It is also shown that the cooling holes of the flame tube walls with diameter less than 2 mm can be neglected in the determination of the acoustic modes in the frequency range of up to 1000 Hz. This reduces the number of the grid-model elements by a factor of six in comparison with a model that considers all of the holes. Furthermore, a method of export of spatial inhomogeneity of the flow parameters from a CFD solver sector model to the annular combustion chamber model in a modal solver is presented. As a result of the obtained model calculation, acoustic modes of the combustion chamber in the frequency range of up to 1000 Hz are determined. For a standard engine condition, a potentially dangerous acoustic mode with a frequency close to the ripple frequency of the precessing vortex core, which is formed behind the burner device of this combustion chamber, is detected.

  2. Modeling Wettability Alteration using Chemical EOR Processes in Naturally Fractured Reservoirs

    SciTech Connect

    Mojdeh Delshad; Gary A. Pope; Kamy Sepehrnoori

    2007-09-30

    The objective of our search is to develop a mechanistic simulation tool by adapting UTCHEM to model the wettability alteration in both conventional and naturally fractured reservoirs. This will be a unique simulator that can model surfactant floods in naturally fractured reservoir with coupling of wettability effects on relative permeabilities, capillary pressure, and capillary desaturation curves. The capability of wettability alteration will help us and others to better understand and predict the oil recovery mechanisms as a function of wettability in naturally fractured reservoirs. The lack of a reliable simulator for wettability alteration means that either the concept that has already been proven to be effective in the laboratory scale may never be applied commercially to increase oil production or the process must be tested in the field by trial and error and at large expense in time and money. The objective of Task 1 is to perform a literature survey to compile published data on relative permeability, capillary pressure, dispersion, interfacial tension, and capillary desaturation curve as a function of wettability to aid in the development of petrophysical property models as a function of wettability. The new models and correlations will be tested against published data. The models will then be implemented in the compositional chemical flooding reservoir simulator, UTCHEM. The objective of Task 2 is to understand the mechanisms and develop a correlation for the degree of wettability alteration based on published data. The objective of Task 3 is to validate the models and implementation against published data and to perform 3-D field-scale simulations to evaluate the impact of uncertainties in the fracture and matrix properties on surfactant alkaline and hot water floods.

  3. A Bayesian network model for assessing natural estrogen fate and transport in a swine waste lagoon.

    PubMed

    Lee, Boknam; Kullman, Seth W; Yost, Erin; Meyer, Michael T; Worley-Davis, Lynn; Williams, C Michael; Reckhow, Kenneth H

    2014-10-01

    Commercial swine waste lagoons are regarded as a major reservoir of natural estrogens, which have the potential to produce adverse physiological effects on exposed aquatic organisms and wildlife. However, there remains limited understanding of the complex mechanisms of physical, chemical, and biological processes that govern the fate and transport of natural estrogens within an anaerobic swine lagoon. To improve lagoon management and ultimately help control the offsite transport of these compounds from swine operations, a probabilistic Bayesian network model was developed to assess natural estrogen fate and budget and then compared against data collected from a commercial swine field site. In general, the model was able to describe the estrogen fate and budget in both the slurry and sludge stores within the swine lagoon. Sensitivity analysis within the model demonstrated that the estrogen input loading from the associated barn facility was the most important factor in controlling estrogen concentrations within the lagoon slurry storage, whereas the settling rate was the most significant factor in the lagoon sludge storage. The degradation reactions were shown to be minor in both stores based on prediction of average total estrogen concentrations. Management scenario evaluations demonstrated that the best possible management options to reduce estrogen levels in the lagoon are either to adjust the estrogen input loading from swine barn facilities or to effectively enhance estrogen bonding with suspended solids through the use of organic polymers or inorganic coagulants. © 2014 SETAC.

  4. Modeling the Manipulation of Natural Populations by the Mutagenic Chain Reaction

    PubMed Central

    Unckless, Robert L.; Messer, Philipp W.; Connallon, Tim; Clark, Andrew G.

    2015-01-01

    The use of recombinant genetic technologies for population manipulation has mostly remained an abstract idea due to the lack of a suitable means to drive novel gene constructs to high frequency in populations. Recently Gantz and Bier showed that the use of CRISPR/Cas9 technology could provide an artificial drive mechanism, the so-called mutagenic chain reaction (MCR), which could lead to rapid fixation of even a deleterious introduced allele. We establish the near equivalence of this system to other gene drive models and review the results of simple models showing that, when there is a fitness cost to the MCR allele, an internal equilibrium may exist that is usually unstable. In this case, introductions must be at a frequency above this critical point for the successful invasion of the MCR allele. We obtain estimates of fixation and invasion probabilities for the appropriate scenarios. Finally, we discuss how polymorphism in natural populations may introduce sources of natural resistance to MCR invasion. These modeling results have important implications for application of MCR in natural populations. PMID:26232409

  5. Modeling the Manipulation of Natural Populations by the Mutagenic Chain Reaction.

    PubMed

    Unckless, Robert L; Messer, Philipp W; Connallon, Tim; Clark, Andrew G

    2015-10-01

    The use of recombinant genetic technologies for population manipulation has mostly remained an abstract idea due to the lack of a suitable means to drive novel gene constructs to high frequency in populations. Recently Gantz and Bier showed that the use of CRISPR/Cas9 technology could provide an artificial drive mechanism, the so-called mutagenic chain reaction (MCR), which could lead to rapid fixation of even a deleterious introduced allele. We establish the near equivalence of this system to other gene drive models and review the results of simple models showing that, when there is a fitness cost to the MCR allele, an internal equilibrium may exist that is usually unstable. In this case, introductions must be at a frequency above this critical point for the successful invasion of the MCR allele. We obtain estimates of fixation and invasion probabilities for the appropriate scenarios. Finally, we discuss how polymorphism in natural populations may introduce sources of natural resistance to MCR invasion. These modeling results have important implications for application of MCR in natural populations.

  6. Modeling virtual organizations with Latent Dirichlet Allocation: a case for natural language processing.

    PubMed

    Gross, Alexander; Murthy, Dhiraj

    2014-10-01

    This paper explores a variety of methods for applying the Latent Dirichlet Allocation (LDA) automated topic modeling algorithm to the modeling of the structure and behavior of virtual organizations found within modern social media and social networking environments. As the field of Big Data reveals, an increase in the scale of social data available presents new challenges which are not tackled by merely scaling up hardware and software. Rather, they necessitate new methods and, indeed, new areas of expertise. Natural language processing provides one such method. This paper applies LDA to the study of scientific virtual organizations whose members employ social technologies. Because of the vast data footprint in these virtual platforms, we found that natural language processing was needed to 'unlock' and render visible latent, previously unseen conversational connections across large textual corpora (spanning profiles, discussion threads, forums, and other social media incarnations). We introduce variants of LDA and ultimately make the argument that natural language processing is a critical interdisciplinary methodology to make better sense of social 'Big Data' and we were able to successfully model nested discussion topics from forums and blog posts using LDA. Importantly, we found that LDA can move us beyond the state-of-the-art in conventional Social Network Analysis techniques.

  7. Engaging Students with the Nature of Science and the Nature of Technology by Modeling the Work of Scientists

    ERIC Educational Resources Information Center

    Kruse, Jerrid W.; Wilcox, Jesse L.

    2013-01-01

    Just as science education is too often limited to the acquisition of facts, technology education is too often limited to proficient use of technology. Neither of these goals fully realize a robust definition of science and technology literacy. To achieve greater science and technology literacy, students must understand the natures of both science…

  8. Engaging Students with the Nature of Science and the Nature of Technology by Modeling the Work of Scientists

    ERIC Educational Resources Information Center

    Kruse, Jerrid W.; Wilcox, Jesse L.

    2013-01-01

    Just as science education is too often limited to the acquisition of facts, technology education is too often limited to proficient use of technology. Neither of these goals fully realize a robust definition of science and technology literacy. To achieve greater science and technology literacy, students must understand the natures of both science…

  9. Drops of water and of soap solution: Students' constraining mental models of the nature of matter

    NASA Astrophysics Data System (ADS)

    Eilam, Billie

    2004-12-01

    This study investigates how 25 junior high school students employed their bodies of knowledge and responded to problem cues while individually performing a science experiment and reasoning about a drops phenomenon. Line-by-line content analysis conducted on students' written ad hoc explanations aimed to reveal students' concepts and their relations within their explanations, and to construe students' mental models for the science phenomenon based on level of specification, models' correspondence with scientific claims, macro versus micro view of matter, and type of evidence used. We then inferred four types of knowledge representations for the nature of matter. Findings are discussed in terms of implications for science teaching.

  10. Preservice Biology Teachers' Conceptions About the Tentative Nature of Theories and Models in Biology

    NASA Astrophysics Data System (ADS)

    Reinisch, Bianca; Krüger, Dirk

    2016-11-01

    In research on the nature of science, there is a need to investigate the role and status of different scientific knowledge forms. Theories and models are two of the most important knowledge forms within biology and are the focus of this study. During interviews, preservice biology teachers (N = 10) were asked about their understanding of theories and models. They were requested to give reasons why they see theories and models as either tentative or certain constructs. Their conceptions were then compared to philosophers' positions (e.g., Popper, Giere). A category system was developed from the qualitative content analysis of the interviews. These categories include 16 conceptions for theories (n tentative = 11; n certain = 5) and 18 conceptions for models (n tentative = 10; n certain = 8). The analysis of the interviews showed that the preservice teachers gave reasons for the tentativeness or certainty of theories and models either due to their understanding of the terms or due to their understanding of the generation or evaluation of theories and models. Therefore, a variety of different terminology, from different sources, should be used in learning-teaching situations. Additionally, an understanding of which processes lead to the generation, evaluation, and refinement or rejection of theories and models should be discussed with preservice teachers. Within philosophy of science, there has been a shift from theories to models. This should be transferred to educational contexts by firstly highlighting the role of models and also their connections to theories.

  11. Modeling the intention to choose natural vaginal delivery: using reasoned action and social cognitive theories.

    PubMed

    Kanani, Safieh; Allahverdipour, Hamid; AsghariJafarabadi, Mohammad

    2015-01-01

    The Behavioral Intention Model is one of the best and most widely models used regarding attitude of behavioral of pregnancy and decrease the rate of cesarean section (CS) among pregnant women, except effect of attitude and subjective norms on behavioral intention. Two variables of self-efficacy, and outcome expectation, relate to individual's behavior in an upcoming situation, and both of them are important at the development of behavior. The purpose of the present study was to develop a model to explain women's inten-tion to choose natural vaginal delivery (NVD). The variables of self-efficacy and outcome expectations, derived from Bandura's Social Cognitive Theory, and Behavioral Intention Model constructs were used to define the model. The study was descriptive and cross-sectional in nature and took place in Pars Abad, Iran in 2014. The non-probability sample consisted of 200 pregnant women who voluntarily participated in the study and provided the data. SPSS 21 and MPLUS 6.8 were employed to analyze the data. Self-efficacy, outcome expectations, and attitude toward NVD were associated with intention to choose the NVD. The study findings may play a role in designing educational interventions aimed at influencing the NVD and improving childbirth programs.

  12. Development of a natural gas systems analysis model (GSAM). Annual report, July 1994--June 1995

    SciTech Connect

    1995-07-01

    North American natural gas markets have changed dramatically over the past decade. A competitive, cost-conscious production, transportation, and distribution system has emerged from the highly regulated transportation wellhead pricing structure of the 1980`s. Technology advances have played an important role in the evolution of the gas industry, a role likely to expand substantially as alternative fuel price competition and a maturing natural gas resource base force operators to maximize efficiency. Finally, significant changes continue in regional gas demand patterns, industry practices, and infrastructure needs. As the complexity of the gas system grows so does the need to evaluate and plan for alternative future resource, technology, and market scenarios. Traditional gas modeling systems focused solely on the econometric aspects of gas marketing. These systems, developed to assess a regulated industry at a high level of aggregation, rely on simple representation of complex and evolving systems, thereby precluding insight into how the industry will change over time. Credible evaluations of specific policy initiatives and research activities require a different approach. Also, the mounting pressure on energy producers from environmental compliance activities requires development of analysis that incorporates relevant geologic, engineering, and project economic details. The objective of policy, research and development (R&D), and market analysis is to integrate fundamental understanding of natural gas resources, technology, and markets to fully describe the potential of the gas resource under alternative future scenarios. This report summarizes work over the past twelve months on DOE Contract DE-AC21-92MC28138, Development of a Natural Gas Systems Analysis Model (GSAM). The products developed under this project directly support the Morgantown Energy Technology Center (METC) in carrying out its natural gas R&D mission.

  13. Applying the natural disasters vulnerability evaluation model to the March 2011 north-east Japan earthquake and tsunami.

    PubMed

    Ruiz Estrada, Mario Arturo; Yap, Su Fei; Park, Donghyun

    2014-07-01

    Natural hazards have a potentially large impact on economic growth, but measuring their economic impact is subject to a great deal of uncertainty. The central objective of this paper is to demonstrate a model--the natural disasters vulnerability evaluation (NDVE) model--that can be used to evaluate the impact of natural hazards on gross national product growth. The model is based on five basic indicators-natural hazards growth rates (αi), the national natural hazards vulnerability rate (ΩT), the natural disaster devastation magnitude rate (Π), the economic desgrowth rate (i.e. shrinkage of the economy) (δ), and the NHV surface. In addition, we apply the NDVE model to the north-east Japan earthquake and tsunami of March 2011 to evaluate its impact on the Japanese economy.

  14. A process-based model to derive methane emissions from natural wetlands

    SciTech Connect

    Walter, B.P.; Heimann, M.; Shannon, R.D.; White, J.R.

    1996-12-01

    A process-based model has been developed in order to calculate methane emissions from natural wetlands as a function of the hydrologic and thermal conditions in the soil. The considered processes in the model are methane production, methane consumption and transport of methane by diffusion, ebullition and through plants. The model has been tested against data from a three-year field study from a Michigan peatland. The interannual and seasonal variations of the modelled methane emissions and methane concentration profiles are in good agreement with the observations. During the growing season the main emission pathway proceeds through plants. Ebullition occurs whenever the water table is above the soil surface, while diffusion is only significant in the first 15 days after a drop of the water table below the peat surface. {copyright} American Geophysical Union 1996

  15. Modeling Responses of Naturally Fractured Geothermal Reservoir to Low-Pressure Stimulation

    DOE Data Explorer

    Fu, Pengcheng; Carrigan, Charles R.

    2012-01-01

    Hydraulic shearing is an appealing reservoir stimulation strategy for Enhanced Geothermal Systems. It is believed that hydro-shearing is likely to simulate a fracture network that covers a relatively large volume of the reservoir whereas hydro-fracturing tends to create a small number of fractures. In this paper, we examine the geomechanical and hydraulic behaviors of natural fracture systems subjected to hydro-shearing stimulation and develop a coupled numerical model within the framework of discrete fracture network modeling. We found that in the low pressure hydro-shearing regime, the coupling between the fluid phase and the rock solid phase is relatively simple, and the numerical model is computationally efficient. Using this modified model, we study the behavior of a random fracture network subjected to hydro-shearing stimulation.

  16. Higgs boson couplings in multi-doublet models with natural flavour conservation

    NASA Astrophysics Data System (ADS)

    Yagyu, Kei

    2016-12-01

    We investigate the deviation in the couplings of the standard model (SM) like Higgs boson (h) with a mass of 125 GeV from the prediction of the SM in multi-doublet models within the framework where flavour changing neutral currents at the tree level are naturally forbidden. After we present the general expressions for the modified gauge and Yukawa couplings for h, we show the correlation between the deviation in the Yukawa coupling for the tau lepton hτ+τ- and that for the bottom quark hb b bar under the assumption of a non-zero deviation in the hVV (V = W , Z) couplings in two Higgs doublet models (2HDMs) and three Higgs doublet models (3HDMs) as simple examples. We clarify the possible allowed prediction of the deviations in the 3HDMs which cannot be explained in the 2HDMs even taking into account the one-loop electroweak corrections to the Yukawa coupling.

  17. Modeling of thermohydraulic transients in a boiling helium natural circulation loop

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.

    2016-12-01

    Boiling helium natural circulation loops are a cooling option for superconducting magnets. Previous studies on the field have provided a thorough understanding of their steady state behavior in all boiling regimes. Recent experimental research has lead to the understanding of their transient behavior. In particular, it highlights the impact of the thermohydraulic evolution of the circuit on the onset of transient boiling crisis, which represents a limitation of the cooling system. Hence, the need of modeling this aspect of these systems. In this work we present modeling options of two-phase helium loops departing from the homogeneous equilibrium two-phase flow model. Reasonable additional assumptions are introduced to obtain a simplified model and the effect of these assumptions is evaluated by comparison with the solution of the non-simplified equations system. These methods are compared to experimental data to analyze their success and limitations.

  18. Enhancement models of momentum densities of annihilating electron-positron pairs: The many-body picture of natural geminals

    NASA Astrophysics Data System (ADS)

    Makkonen, Ilja; Ervasti, Mikko M.; Siro, Topi; Harju, Ari

    2014-01-01

    The correlated motion of a positron surrounded by electrons is a fundamental many-body problem. We approach this by modeling the momentum density of annihilating electron-positron pairs using the framework of reduced density matrices, natural orbitals, and natural geminals (electron-positron pair wave functions) of the quantum theory of many-particle systems. We find that an expression based on the natural geminals provides an exact, unique, and compact expression for the momentum density. The natural geminals can be used to define and to determine enhancement factors for enhancement models going beyond the independent-particle model for a better understanding of the results of positron annihilation experiments.

  19. Can Geostatistical Models Represent Nature's Variability? An Analysis Using Flume Experiments

    NASA Astrophysics Data System (ADS)

    Scheidt, C.; Fernandes, A. M.; Paola, C.; Caers, J.

    2015-12-01

    The lack of understanding in the Earth's geological and physical processes governing sediment deposition render subsurface modeling subject to large uncertainty. Geostatistics is often used to model uncertainty because of its capability to stochastically generate spatially varying realizations of the subsurface. These methods can generate a range of realizations of a given pattern - but how representative are these of the full natural variability? And how can we identify the minimum set of images that represent this natural variability? Here we use this minimum set to define the geostatistical prior model: a set of training images that represent the range of patterns generated by autogenic variability in the sedimentary environment under study. The proper definition of the prior model is essential in capturing the variability of the depositional patterns. This work starts with a set of overhead images from an experimental basin that showed ongoing autogenic variability. We use the images to analyze the essential characteristics of this suite of patterns. In particular, our goal is to define a prior model (a minimal set of selected training images) such that geostatistical algorithms, when applied to this set, can reproduce the full measured variability. A necessary prerequisite is to define a measure of variability. In this study, we measure variability using a dissimilarity distance between the images. The distance indicates whether two snapshots contain similar depositional patterns. To reproduce the variability in the images, we apply an MPS algorithm to the set of selected snapshots of the sedimentary basin that serve as training images. The training images are chosen from among the initial set by using the distance measure to ensure that only dissimilar images are chosen. Preliminary investigations show that MPS can reproduce fairly accurately the natural variability of the experimental depositional system. Furthermore, the selected training images provide

  20. Modeling study of natural emissions, source apportionment, and emission control of atmospheric mercury

    NASA Astrophysics Data System (ADS)

    Shetty, Suraj K.

    Mercury (Hg) is a toxic pollutant and is important to understand its cycling in the environment. In this dissertation, a number of modeling investigations were conducted to better understand the emission from natural surfaces, the source-receptor relationship of the emissions, and emission reduction of atmospheric mercury. The first part of this work estimates mercury emissions from vegetation, soil and water surfaces using a number of natural emission processors and detailed (LAI) Leaf Area Index data from GIS (Geographic Information System) satellite products. East Asian domain was chosen as it contributes nearly 50% of the global anthropogenic mercury emissions into the atmosphere. The estimated annual natural mercury emissions (gaseous elemental mercury) in the domain are 834 Mg yr-1 with 462 Mg yr-1 contributing from China. Compared to anthropogenic sources, natural sources show greater seasonal variability (highest in simmer). The emissions are significant, sometimes dominant, contributors to total mercury emission in the regions. The estimates provide possible explanation for the gaps between the anthropogenic emission estimates based on activity data and the emission inferred from field observations in the regions. To understand the contribution of domestic emissions to mercury deposition in the United States, the second part of the work applies the mercury model of Community Multi-scale Air Quality Modeling system (CMAQ-Hg v4.6) to apportion the various emission sources attributing to the mercury wet and dry deposition in the 6 United States receptor regions. Contributions to mercury deposition from electric generating units (EGU), iron and steel industry (IRST), industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC) in domain was estimated. The model results for 2005 compared reasonably well to field observations made by MDN (Mercury Deposition Network

  1. Constraining Methane Emissions from Natural Gas Production in Northeastern Pennsylvania Using Aircraft Observations and Mesoscale Modeling

    NASA Astrophysics Data System (ADS)

    Barkley, Z.; Davis, K.; Lauvaux, T.; Miles, N.; Richardson, S.; Martins, D. K.; Deng, A.; Cao, Y.; Sweeney, C.; Karion, A.; Smith, M. L.; Kort, E. A.; Schwietzke, S.

    2015-12-01

    Leaks in natural gas infrastructure release methane (CH4), a potent greenhouse gas, into the atmosphere. The estimated fugitive emission rate associated with the production phase varies greatly between studies, hindering our understanding of the natural gas energy efficiency. This study presents a new application of inverse methodology for estimating regional fugitive emission rates from natural gas production. Methane observations across the Marcellus region in northeastern Pennsylvania were obtained during a three week flight campaign in May 2015 performed by a team from the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division and the University of Michigan. In addition to these data, CH4 observations were obtained from automobile campaigns during various periods from 2013-2015. An inventory of CH4 emissions was then created for various sources in Pennsylvania, including coalmines, enteric fermentation, industry, waste management, and unconventional and conventional wells. As a first-guess emission rate for natural gas activity, a leakage rate equal to 2% of the natural gas production was emitted at the locations of unconventional wells across PA. These emission rates were coupled to the Weather Research and Forecasting model with the chemistry module (WRF-Chem) and atmospheric CH4 concentration fields at 1km resolution were generated. Projected atmospheric enhancements from WRF-Chem were compared to observations, and the emission rate from unconventional wells was adjusted to minimize errors between observations and simulation. We show that the modeled CH4 plume structures match observed plumes downwind of unconventional wells, providing confidence in the methodology. In all cases, the fugitive emission rate was found to be lower than our first guess. In this initial emission configuration, each well has been assigned the same fugitive emission rate, which can potentially impair our ability to match the observed spatial variability

  2. Modeling the Long-Term Isolation Performance of Natural and Engineered Geologic CO2 Storage Sites

    SciTech Connect

    Johnson, J W; Nitao, J J; Morris, J P

    2004-07-26

    Long-term cap rock integrity represents the single most important constraint on the long-term isolation performance of natural and engineered geologic CO{sub 2} storage sites. CO{sub 2} influx that forms natural accumulations and CO{sub 2} injection for EOR/sequestration or saline-aquifer disposal both lead to concomitant geochemical alteration and geomechanical deformation of the cap rock, enhancing or degrading its seal integrity depending on the relative effectiveness of these interdependent processes. This evolution of cap-rock permeability can be assessed through reactive transport modeling, an advanced computational method based on mathematical models of the coupled physical and chemical processes catalyzed by the influx event. Using our reactive transport simulator (NUFT), supporting geochemical databases and software (SUPCRT92), and distinct-element geomechanical model (LDEC), we have shown that influx-triggered mineral dissolution/precipitation reactions within typical shale cap rocks continuously reduce microfrac apertures, while pressure and effective-stress evolution first rapidly increase then slowly constrict them. For a given shale composition, the extent of geochemical enhancement is nearly independent of key reservoir properties (permeability and lateral continuity) that distinguish saline aquifer and EOR/sequestration settings and CO{sub 2} influx parameters (rate, focality, and duration) that distinguish engineered disposal sites and natural accumulations, because these characteristics and parameters have negligible impact on mineral reaction rates. In contrast, the extent of geomechanical degradation is highly dependent on these reservoir properties and influx parameters, because they effectively dictate magnitude of the pressure perturbation. Specifically, initial geomechanical degradation has been shown inversely proportional to reservoir permeability and lateral continuity and proportional to influx rate. As a result, while the extent of

  3. Nature of science in instruction materials of science through the model of educational reconstruction

    NASA Astrophysics Data System (ADS)

    Azizah, Nur; Mudzakir, Ahmad

    2016-02-01

    The study was carried out to reconstruct the science teaching materials charged view of the nature of science (VNOS). This reconstruction process using the Model of Educational Reconstruction (MER), which is the framework for research and development of science education as well as a guide for planning the teaching of science in the schools is limited in two stages, namely: content structure analysis, and empirical studies of learners. The purpose of this study is to obtain a pre-conception of learners and prospective scientists to the topic of the nature of the material and utilization. The method used to descriptive with the instruments is guidelines for interviews for 15 students of class VIII, text analysis sheet, sheet analysis of the concept, and the validation sheet indicators and learning objectives NOS charged on cognitive and affective aspects. The results obtained in the form of pre-conceptions of learners who demonstrate almost 100% of students know the types of materials and some of its nature, the results of the scientist's perspective on the topic of the nature of the material and its use, as well as the results of the validation indicators and learning objectives charged NOS and competencies PISA 2015 cognitive and affective aspects with CVI value of 0.99 and 1.0 after being validated by five experts. This suggests that the indicators and the resulting learning objectives feasible and can proceed to the reconstruction of teaching materials on the topic of material properties and utilization.

  4. Natural attenuation model and biodegradation for 1,1,1-trichloroethane contaminant in shallow groundwater

    PubMed Central

    Lu, Qiang; Zhu, Rui-Li; Yang, Jie; Li, Hui; Liu, Yong-Di; Lu, Shu-Guang; Luo, Qi-Shi; Lin, Kuang-Fei

    2015-01-01

    Natural attenuation is an effective and feasible technology for controlling groundwater contamination. This study investigated the potential effectiveness and mechanisms of natural attenuation of 1,1,1-trichloroethane (TCA) contaminants in shallow groundwater in Shanghai by using a column simulation experiment, reactive transport model, and 16S rRNA gene clone library. The results indicated that the majority of the contaminant mass was present at 2–6 m in depth, the contaminated area was approximately 1000 m × 1000 m, and natural attenuation processes were occurring at the site. The effluent breakthrough curves from the column experiments demonstrated that the effectiveness of TCA natural attenuation in the groundwater accorded with the advection-dispersion-reaction equation. The kinetic parameter of adsorption and biotic dehydrochlorination of TCA was 0.068 m3/kg and 0.0045 d–1. The contamination plume was predicted to diminish and the maximum concentration of TCA decreased to 280 μg/L. The bacterial community during TCA degradation in groundwater belonged to Trichococcus, Geobacteraceae, Geobacter, Mucilaginibacter, and Arthrobacter. PMID:26379629

  5. Bringing Chatbots into education: Towards Natural Language Negotiation of Open Learner Models

    NASA Astrophysics Data System (ADS)

    Kerlyl, Alice; Hall, Phil; Bull, Susan

    There is an extensive body of work on Intelligent Tutoring Systems: computer environments for education, teaching and training that adapt to the needs of the individual learner. Work on personalisation and adaptivity has included research into allowing the student user to enhance the system's adaptivity by improving the accuracy of the underlying learner model. Open Learner Modelling, where the system's model of the user's knowledge is revealed to the user, has been proposed to support student reflection on their learning. Increased accuracy of the learner model can be obtained by the student and system jointly negotiating the learner model. We present the initial investigations into a system to allow people to negotiate the model of their understanding of a topic in natural language. This paper discusses the development and capabilities of both conversational agents (or chatbots) and Intelligent Tutoring Systems, in particular Open Learner Modelling. We describe a Wizard-of-Oz experiment to investigate the feasibility of using a chatbot to support negotiation, and conclude that a fusion of the two fields can lead to developing negotiation techniques for chatbots and the enhancement of the Open Learner Model. This technology, if successful, could have widespread application in schools, universities and other training scenarios.

  6. Modeling Natural Convection in Copper Electrorefining: Describing Turbulence Behavior for Industrial-Sized Systems

    NASA Astrophysics Data System (ADS)

    Leahy, Martin J.; Phillip Schwarz, M.

    2011-08-01

    A computational fluid dynamics (CFD) model of copper electrorefining is discussed, where natural convection flow is driven by buoyancy forces caused by gradients in copper concentration at the electrodes. We provide experimental validation of the CFD model for several cases varying in size from a small laboratory scale to large industrial scale, including one that has not been compared with a CFD model. Previously, the large-scale systems have been thought to be turbulent by some workers and modeled accordingly with k-ɛ type turbulence models, but others have not considered turbulence effects in their modeling. We find that the turbulence model does not predict turbulence exists; however, we analyze carefully the fluctuation statistics predicted for a transient model, finding that most cases considered do exhibit a type of turbulence, an instability related to the interaction between velocity and copper concentration fields. We provide a comparison of the extent of turbulence for various electrode heights, and gap widths, and we emphasize industrial-sized electrorefining cells.

  7. Integrated Modeling of the Human-Natural System to Improve Local Water Management and Planning

    NASA Astrophysics Data System (ADS)

    Gutowski, W. J., Jr.; Dziubanski, D.; Franz, K.; Goodwin, J.; Rehmann, C. R.; Simpkins, W. W.; Tesfastion, L.; Wanamaker, A. D.; Jie, Y.

    2015-12-01

    Communities across the world are experiencing the effects of unsustainable water management practices. Whether the problem is a lack of water, too much water, or water of degraded quality, finding acceptable solutions requires community-level efforts that integrate sound science with local needs and values. Our project develops both a software technology (agent-based hydrological modeling) and a social technology (a participatory approach to model development) that will allow communities to comprehensively address local water challenges. Using agent-based modeling (ABM), we are building a modeling system that includes a semi-distributed hydrologic process model coupled with agent (stakeholder) models. Information from the hydrologic model is conveyed to the agent models, which, along with economic information, determine appropriate agent actions that subsequently affect hydrology within the model. The iterative participatory modeling (IPM) process will assist with the continual development of the agent models. Further, IPM creates a learning environment in which all participants, including researchers, are co-exploring relevant data, possible scenarios and solutions, and viewpoints through continuous interactions. Our initial work focuses on the impact of flood mitigation and conservation efforts on reducing flooding in an urban area. We are applying all research elements above to the Squaw Creek watershed that flows through parts of four counties in central Iowa. The watershed offers many of the typical tensions encountered in Iowa, such as different perspectives on water management between upstream farmers and downstream urban areas, competition for various types of recreational services, and increasing absentee land ownership that may conflict with community values. Ultimately, climate change scenarios will be incorporated into the model to determine long term patterns that may develop within the social or natural system.

  8. A stochastic equilibrium model for the North American natural gas market

    NASA Astrophysics Data System (ADS)

    Zhuang, Jifang

    This dissertation is an endeavor in the field of energy modeling for the North American natural gas market using a mixed complementarity formulation combined with the stochastic programming. The genesis of the stochastic equilibrium model presented in this dissertation is the deterministic market equilibrium model developed in [Gabriel, Kiet and Zhuang, 2005]. Based on some improvements that we made to this model, including proving new existence and uniqueness results, we present a multistage stochastic equilibrium model with uncertain demand for the deregulated North American natural gas market using the recourse method of the stochastic programming. The market participants considered by the model are pipeline operators, producers, storage operators, peak gas operators, marketers and consumers. Pipeline operators are described with regulated tariffs but also involve "congestion pricing" as a mechanism to allocate scarce pipeline capacity. Marketers are modeled as Nash-Cournot players in sales to the residential and commercial sectors but price-takers in all other aspects. Consumers are represented by demand functions in the marketers' problem. Producers, storage operators and peak gas operators are price-takers consistent with perfect competition. Also, two types of the natural gas markets are included: the long-term and spot markets. Market participants make both high-level planning decisions (first-stage decisions) in the long-term market and daily operational decisions (recourse decisions) in the spot market subject to their engineering, resource and political constraints, resource constraints as well as market constraints on both the demand and the supply side, so as to simultaneously maximize their expected profits given others' decisions. The model is shown to be an instance of a mixed complementarity problem (MiCP) under minor conditions. The MiCP formulation is derived from applying the Karush-Kuhn-Tucker optimality conditions of the optimization problems

  9. Landslides! Engaging students in natural hazards and STEM principles through the exploration of landslide analog models

    NASA Astrophysics Data System (ADS)

    Gochis, E. E.; Lechner, H. N.; Brill, K. A.; Lerner, G.; Ramos, E.

    2014-12-01

    Graduate students at Michigan Technological University developed the "Landslides!" activity to engage middle & high school students participating in summer engineering programs in a hands-on exploration of geologic engineering and STEM (Science, Technology, Engineering and Math) principles. The inquiry-based lesson plan is aligned to Next Generation Science Standards and is appropriate for 6th-12th grade classrooms. During the activity students focus on the factors contributing to landslide development and engineering practices used to mitigate hazards of slope stability hazards. Students begin by comparing different soil types and by developing predictions of how sediment type may contribute to differences in slope stability. Working in groups, students then build tabletop hill-slope models from the various materials in order to engage in evidence-based reasoning and test their predictions by adding groundwater until each group's modeled slope fails. Lastly students elaborate on their understanding of landslides by designing 'engineering solutions' to mitigate the hazards observed in each model. Post-evaluations from students demonstrate that they enjoyed the hands-on nature of the activity and the application of engineering principles to mitigate a modeled natural hazard.

  10. Modeling study of the natural state of the Heber geothermal field, California

    SciTech Connect

    Lippmann, M.J.; Bodvarsson, G.S.

    1983-06-01

    As a first step in simulating the behavior of the Heber field under exploitation, the system is modeled in its natural (pre-exploitation) state. Using Lawrence Berkeley Laboratory's (LBL) computer code PT and a radially symmetric model, a reasonable match between published and calculated temperature and pressure distributions is obtained. The results of the study indicate that the Heber geothermal system is created by the upflow of hot water through a central zone of higher permeability. The model shows that in its natural state the system is recharged at depth by a 15 MW(thermal) convective heat source. The existence of a radially symmetric convection pattern, whose axis coincides with that of the Heber anomaly is suggested. At the lower part of the ascending hot water plume, the deep recharge water mixes with colder water moving laterally towards the axis of the system. On the upper part, the rising plume spreads radially outward before reaching the bottom of the caprock, at 550 m depth. The model results suggest that the caprock is quite permeable, with convection controlling the temperature distribution. The low permeability of the upper zones in the outer region of the system may be due to mineral precipitation.

  11. Semiparametric Modeling of Daily Ammonia Levels in Naturally Ventilated Caged-Egg Facilities

    PubMed Central

    Gutiérrez-Zapata, Diana María; Galeano-Vasco, Luis Fernando; Cerón-Muñoz, Mario Fernando

    2016-01-01

    Ammonia concentration (AMC) in poultry facilities varies depending on different environmental conditions and management; however, this is a relatively unexplored subject in Colombia (South America). The objective of this study was to model daily AMC variations in a naturally ventilated caged-egg facility using generalized additive models. Four sensor nodes were used to record AMC, temperature, relative humidity and wind speed on a daily basis, with 10 minute intervals for 12 weeks. The following variables were included in the model: Heat index, Wind, Hour, Location, Height of the sensor to the ground level, and Period of manure accumulation. All effects included in the model were highly significant (p<0.001). The AMC was higher during the night and early morning when the wind was not blowing (0.0 m/s) and the heat index was extreme. The average and maximum AMC were 5.94±3.83 and 31.70 ppm, respectively. Temperatures above 25°C and humidity greater than 80% increased AMC levels. In naturally ventilated caged-egg facilities the daily variations observed in AMC primarily depend on cyclic variations of the environmental conditions and are also affected by litter handling (i.e., removal of the bedding material). PMID:26812150

  12. Technosocial Modeling for Determining the Status and Nature of a State’s Nuclear Activities

    SciTech Connect

    Gastelum, Zoe N.; Harvey, Julia B.

    2009-09-25

    The International Atomic Energy Agency State Evaluation Process: The Role of Information Analysis in Reaching Safeguards Conclusions (Mathews et al. 2008), several examples of nonproliferation models using analytical software were developed that may assist the IAEA with collecting, visualizing, analyzing, and reporting information in support of the State Evaluation Process. This paper focuses on one of the examples a set of models developed in the Proactive Scenario Production, Evidence Collection, and Testing (ProSPECT) software that evaluates the status and nature of a state’s nuclear activities. The models use three distinct subject areas to perform this assessment: the presence of nuclear activities, the consistency of those nuclear activities with national nuclear energy goals, and the geopolitical context in which those nuclear activities are taking place. As a proof-of-concept for the models, a crude case study was performed. The study, which attempted to evaluate the nuclear activities taking place in Syria prior to September 2007, yielded illustrative, yet inconclusive, results. Due to the inconclusive nature of the case study results, changes that may improve the model’s efficiency and accuracy are proposed.

  13. Biomechanical analysis comparing natural and alloplastic temporomandibular joint replacement using a finite element model.

    PubMed

    Mesnard, Michel; Ramos, Antonio; Ballu, Alex; Morlier, Julien; Cid, M; Simoes, J A

    2011-04-01

    Prosthetic materials and bone present quite different mechanical properties. Consequently, mandible reconstruction with metallic materials (or a mandible condyle implant) modifies the physiologic behavior of the mandible (stress, strain patterns, and condyle displacements). The changing of bone strain distribution results in an adaptation of the temporomandibular joint, including articular contacts. Using a validated finite element model, the natural mandible strains and condyle displacements were evaluated. Modifications of strains and displacements were then assessed for 2 different temporomandibular joint implants. Because materials and geometry play important key roles, mechanical properties of cortical bone were taken into account in models used in finite element analysis. The finite element model allowed verification of the worst loading configuration of the mandibular condyle. Replacing the natural condyle by 1 of the 2 tested implants, the results also show the importance of the implant geometry concerning biomechanical mandibular behavior. The implant geometry and stiffness influenced mainly strain distribution. The different forces applied to the mandible by the elevator muscles, teeth, and joint loads indicate that the finite element model is a relevant tool to optimize implant geometry or, in a subsequent study, to choose a more suitable distribution of the screws. Bone screws (number and position) have a significant influence on mandibular behavior and on implant stress pattern. Stress concentration and implant fracture must be avoided. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  14. Semiparametric Modeling of Daily Ammonia Levels in Naturally Ventilated Caged-Egg Facilities.

    PubMed

    Gutiérrez-Zapata, Diana María; Galeano-Vasco, Luis Fernando; Cerón-Muñoz, Mario Fernando

    2016-01-01

    Ammonia concentration (AMC) in poultry facilities varies depending on different environmental conditions and management; however, this is a relatively unexplored subject in Colombia (South America). The objective of this study was to model daily AMC variations in a naturally ventilated caged-egg facility using generalized additive models. Four sensor nodes were used to record AMC, temperature, relative humidity and wind speed on a daily basis, with 10 minute intervals for 12 weeks. The following variables were included in the model: Heat index, Wind, Hour, Location, Height of the sensor to the ground level, and Period of manure accumulation. All effects included in the model were highly significant (p<0.001). The AMC was higher during the night and early morning when the wind was not blowing (0.0 m/s) and the heat index was extreme. The average and maximum AMC were 5.94±3.83 and 31.70 ppm, respectively. Temperatures above 25°C and humidity greater than 80% increased AMC levels. In naturally ventilated caged-egg facilities the daily variations observed in AMC primarily depend on cyclic variations of the environmental conditions and are also affected by litter handling (i.e., removal of the bedding material).

  15. Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan

    NASA Astrophysics Data System (ADS)

    Hwang, Ruey-Lung; Lin, Tzu-Ping; Chen, Chen-Peng; Kuo, Nai-Jung

    2009-03-01

    Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1-28.4°C and 17.6-30.0°C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7°C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

  16. Investigating the adaptive model of thermal comfort for naturally ventilated school buildings in Taiwan.

    PubMed

    Hwang, Ruey-Lung; Lin, Tzu-Ping; Chen, Chen-Peng; Kuo, Nai-Jung

    2009-03-01

    Divergence in the acceptability to people in different regions of naturally ventilated thermal environments raises a concern over the extent to which the ASHRAE Standard 55 may be applied as a universal criterion of thermal comfort. In this study, the ASHRAE 55 adaptive model of thermal comfort was investigated for its applicability to a hot and humid climate through a long-term field survey performed in central Taiwan among local students attending 14 elementary and high schools during September to January. Adaptive behaviors, thermal neutrality, and thermal comfort zones are explored. A probit analysis of thermal acceptability responses from students was performed in place of the conventional linear regression of thermal sensation votes against operative temperature to investigate the limits of comfort zones for 90% and 80% acceptability; the corresponding comfort zones were found to occur at 20.1-28.4 degrees C and 17.6-30.0 degrees C, respectively. In comparison with the yearly comfort zones recommended by the adaptive model for naturally ventilated spaces in the ASHRAE Standard 55, those observed in this study differ in the lower limit for 80% acceptability, with the observed level being 1.7 degrees C lower than the ASHRAE-recommended value. These findings can be generalized to the population of school children, thus providing information that can supplement ASHRAE Standard 55 in evaluating the thermal performance of naturally ventilated school buildings, particularly in hot-humid areas such as Taiwan.

  17. Comparing Price Forecast Accuracy of Natural Gas Models andFutures Markets

    SciTech Connect

    Wong-Parodi, Gabrielle; Dale, Larry; Lekov, Alex

    2005-06-30

    The purpose of this article is to compare the accuracy of forecasts for natural gas prices as reported by the Energy Information Administration's Short-Term Energy Outlook (STEO) and the futures market for the period from 1998 to 2003. The analysis tabulates the existing data and develops a statistical comparison of the error between STEO and U.S. wellhead natural gas prices and between Henry Hub and U.S. wellhead spot prices. The results indicate that, on average, Henry Hub is a better predictor of natural gas prices with an average error of 0.23 and a standard deviation of 1.22 than STEO with an average error of -0.52 and a standard deviation of 1.36. This analysis suggests that as the futures market continues to report longer forward prices (currently out to five years), it may be of interest to economic modelers to compare the accuracy of their models to the futures market. The authors would especially like to thank Doug Hale of the Energy Information Administration for supporting and reviewing this work.

  18. Natural experimental models: The global search for biomedical paradigms among traditional, modernizing, and modern populations

    PubMed Central

    Garruto, R. M.; Little, M. A.; James, G. D.; Brown, D. E.

    1999-01-01

    During the past four decades, biomedical scientists have slowly begun to recognize the unique opportunities for studying biomedical processes, disease etiology, and mechanisms of pathogenesis in populations with unusual genetic structures, physiological characteristics, focal endemic disease, or special circumstances. Such populations greatly extend our research capabilities and provide a natural laboratory for studying relationships among biobehavioral, genetic, and ecological processes that are involved in the development of disease. The models presented illustrate three different types of natural experiments: those occurring in traditionally living, modernizing, and modern populations. The examples are drawn from current research that involves population mechanisms of adaptation among East African Turkana pastoralists; a search for etiology and mechanisms of pathogenesis of an emerging disease among the Yakut people of Siberia; and psychosocial stress, hypertension, and cardiovascular disease in women working outside the home in New York City and among subpopulations in Hawaii. The models in general, and the examples in specific, represent natural laboratories in which relatively small intrapopulation differences and large interpopulation differences can be used to evaluate health and disease outcomes. PMID:10468644

  19. Natural and sexual selection giveth and taketh away reproductive barriers: models of population divergence in guppies.

    PubMed

    Labonne, Jacques; Hendry, Andrew P

    2010-07-01

    The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.

  20. A Test of the Optimality Approach to Modelling Canopy gas Exchange by Natural Vegetation

    NASA Astrophysics Data System (ADS)

    Schymanski, S. J.; Sivapalan, M.; Roderick, M. L.; Beringer, J.; Hutley, L. B.

    2005-12-01

    Natural vegetation has co-evolved with its environment over a long period of time and natural selection has led to a species composition that is most suited for the given conditions. Part of this adaptation is the vegetation's water use strategy, which determines the amount and timing of water extraction from the soil. Knowing that water extraction by vegetation often accounts for over 90% of the annual water balance in some places, we need to understand its controls if we want to properly model the hydrologic cycle. Water extraction by roots is driven by transpiration from the canopy, which in turn is an inevitable consequence of CO2 uptake for photosynthesis. Photosynthesis provides plants with their main building material, carbohydrates, and with the energy necessary to thrive and prosper in their environment. Therefore we expect that natural vegetation would have evolved an optimal water use strategy to maximise its `net carbon profit' (the difference between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake). Based on this hypothesis and on an ecophysiological gas exchange and photosynthesis model (Cowan and Farquhar 1977; von Caemmerer 2000), we model the optimal vegetation for a site in Howard Springs (N.T., Australia) and compare the modelled fluxes with measurements by Beringer, Hutley et al. (2003). The comparison gives insights into theoretical and real controls on transpiration and photosynthesis and tests the optimality approach to modelling gas exchange of natural vegetation with unknown properties. The main advantage of the optimality approach is that no assumptions about the particular vegetation on a site are needed, which makes it very powerful for predicting vegetation response to long-term climate- or land use change. Literature: Beringer, J., L. B. Hutley, et al. (2003). "Fire impacts on surface heat, moisture and carbon fluxes from a tropical savanna in northern Australia." International

  1. Synchronized Chaos in Geophysical Fluid Dynamics and in the Predictive Modeling of Natural Systems

    NASA Astrophysics Data System (ADS)

    Duane, Gregory S.

    2008-03-01

    The ubiquitous phenomenon of synchronization among regular oscillators in Nature has been shown, in the past two decades, to extend to chaotic systems. Despite sensitive dependence on initial conditions, two chaotic systems will commonly fall into synchronized motion along their strange attractors when only some of the many degrees of freedom of one system are coupled to corresponding variables in the other. In geophysical fluid models, synchronization can mediate scale interactions, so that coupling of degrees of freedom that describe medium-scale components of the flow can result in synchronization, or partial synchronization, at all scales. Chaos synchronization has been used to interpret non-local "teleconnection" patterns in the Earth's climate system and to predict new ones. In the realm of practical meteorology, the fact that two PDE systems, conceived as "truth" and "model", respectively, can be made to synchronize when coupled at only a discrete set of points, explains how observations at a discrete set of weather stations can be sufficient for weather prediction by a synchronously coupled model. Minimizing synchronization error leads to general recipes for assimilation of observed data into a running model that systematize the treatment of nonlinearities in the dynamical equations. Equations can generally be added to adapt parameters as well as states as the model is running, so that the model "learns". The synchronization view of predictive modelling extends to any translationally- any PDE with constant coefficients, the general form of physical theories. The reliance on synchronicity as an organizing principle in Nature, alternative to causality, has philosophical roots in the collaboration of Carl Jung and Wolfgang Pauli, on the one hand, and in traditions outside of European science, on the other.

  2. Evaluating Engagement Models for a Citizen Science Project: Lessons Learned From Four Years of Nature's Notebook

    NASA Astrophysics Data System (ADS)

    Crimmins, T. M.; Rosemartin, A.

    2012-12-01

    The success of citizen science programs hinges on their abilities to recruit and maintain active participants. The USA National Phenology Network's plant and animal phenology observation program, Nature's Notebook, has been active since 2009. This program engages thousands of citizen scientists in tracking plant and animal life cycle activity over the course of the year. We embarked on an evaluation of the various observer recruitment and retention tactics that we have employed over the ~4-year life of this program to better inform future outreach efforts specific to Nature's Notebook and for the broader citizen science community. Participants in Nature's Notebook may become engaged via one of three pathways: individuals may join Nature's Notebook directly, they may be invited to join through a USA-NPN partner organization, or they may engage through a group with local, site-based leadership. The level and type of recruitment tactics, training, and retention efforts that are employed varies markedly among these three models. In this evaluation, we compared the efficacy of these three engagement models using several metrics: number of individuals recruited, number of individuals that go on to submit at least one data point, retention rates over time, duration of activity, and quantity of data points submitted. We also qualitatively considered the differences in costs the three models require to support. In terms of recruitment, direct engagement yielded 20-100 times more registrants than other two models. In contrast, rates of participation were highest for site-based leadership (>35%, versus 20-30% for direct engagement; rates for partner organizations were highly variable due to small sample sizes). Individuals participating through partners with site-based leadership showed a much higher rate of retention (41% of participants remained active for two+ years) than those participating directly in Nature's Notebook (27% of participants remained active for two+ years

  3. Modeling water balance distribution in a natural semiarid region of central Mexico using a SVAT model

    NASA Astrophysics Data System (ADS)

    Mastachi-Loza, C. A.; Braud, I.; Gonzalez-Sosa, E.; Centro de Investigaciones Del Agua de Querétaro

    2010-12-01

    Around the world water is becoming insufficient, especially in the semiarid regions where there is a high inter-annual variability in the amount and distribution of the rainfall. Studies on this kind of environments would allow us to understand the mechanisms that determine the spatial and temporal distribution of the water balance components. The study was carried out from October 2005 to October 2008 in two semiarid sites located in the south of the Mexican Plateau: El Carmen in Guanajuato State and Cadereyta in Queretaro State. The work aim was to provide a better understanding of the hydrological processes that occur in semiarid ecosystems, quantifying and modeling the water balance in order to define the distribution of the water and energy balance components in El Carmen and Cadereyta. For this purpose, the SiSPAT (Simple Soil Plant Atmosphere Transfer) model was used based on a parameterization of the soil, plants and atmosphere components. It was found that, using SiSPAT, the water balance components were particularly sensitive to parameters associated with the soil and the leaf area index. The model results showed that during the studied period, the annual evapotranspiration in Cadereyta was less than PG (-10 and -5%) and above PG for El Carmen (10 y 30%). Runoff and percolation at 5m were null. Finally in both sites there was a simulated loss of water stored in the soil.

  4. Experimental and modeling analysis of coupled non-Fickian transport and sorption in natural soils

    NASA Astrophysics Data System (ADS)

    Rubin, Shira; Dror, Ishai; Berkowitz, Brian

    2012-05-01

    We present experimental breakthrough curve (BTC) data and a modeling investigation of conservative and sorbing tracer transport in natural soils. By analyzing the data using the continuous time random walk (CTRW) model, we probe the traditional approach of using conservative tracer model parameters as a basis for quantifying the transport of sorbing solutes in the same domain when non-Fickian transport is present. Many known contaminants in groundwater are sorbed to the host solid porous medium, to varying extents, while being transported; this enhances the long tailing of BTCs which often already occurs because of the inherent non-Fickian nature of the transport. The CTRW framework has been shown to account very well for non-Fickian conservative (nonsorbing) transport. Here, we examine two BTC data sets in laboratory columns packed with natural soils; the first (previously analyzed by Mao and Ren (2004)) comprises transport of (conservative) bromide and (sorbing) atrazine tracers, while the second presents new data with bromide and tribromoneopentyl alcohol (TBNPA), a key flame retardant, as a sorbing solute. TBNPA has received little attention in the past, and is shown to be sorbed onto Bet Dagan soil in a nonlinear manner. We find that the transport behavior of bromide is non-Fickian in all cases, which is caused by the heterogeneity of the soil. Comparative model analysis of the non-Fickian BTCs of the conservative, and sorbing tracers and examination of the fitting parameters, exemplify the coupling between transport and adsorption/desorption processes. The difference in transport parameters used to match the conservative and sorbing data sets shows that conservative tracer parameters (average velocity and dispersion coefficient) are not valid for the transport of reactive tracers.

  5. New physics at the weak scale: axigluon models, scale invariance and naturalness, and interacting dark matter

    NASA Astrophysics Data System (ADS)

    Tavares, Gustavo Marques

    The Standard Model of particle physics describes all known elementary particles and their interactions. Despite its great experimental success, we know that the Standard Model is not a complete description of Nature and therefore new phenomena should be observed at higher energies. In the coming years the Large Hadron Collider will test the Standard Model by colliding protons with center of mass energies of up to 14 TeV providing some of the most stringent tests on the Standard Model. Experimental searches for Dark Matter provide a complementary program to test physics at the weak scale. In the near future new experimental data coming from direct detection experiments, and from satellites and telescopes will drastically improve our sensitivity to weak scale dark matter. This could lead to the first direct observation of dark matter, and thus of physics beyond the Standard Model. In this thesis I propose different extensions of the Standard Model and discuss their experimental consequences. I first discuss models for Axigluons, which are spin one particles in the adjoint representation of the SU(3) color gauge group. These models were motivated by the measurement of higher than predicted forward-backward asymmetry in top quark pair production at the Tevatron. I study different scenarios for Axigluon models that can explain the Tevatron result and explore their signatures at the Large Hadron Collider. Second I discuss the implications of ultraviolet scale invariance for the Standard Model, which has been advocated as a solution to the hierarchy problem. I show that in order to solve the hierarchy problem with scale invariance, new physics is required not far from the weak scale. In the last part of this thesis I propose a new model for dark matter, in which dark matter is charged under a hidden non-Abelian gauge group. This leads to modifications in the sensitivity of the usual experimental searches for dark matter in addition to distinct signatures in the Cosmic

  6. Modelling filovirus maintenance in nature by experimental transmission of Marburg virus between Egyptian rousette bats

    PubMed Central

    Schuh, Amy J.; Amman, Brian R.; Jones, Megan E. B.; Sealy, Tara K.; Uebelhoer, Luke S.; Spengler, Jessica R.; Martin, Brock E.; Coleman-McCray, Jo Ann D.; Nichol, Stuart T.; Towner, Jonathan S.

    2017-01-01

    The Egyptian rousette bat (ERB) is a natural reservoir host for Marburg virus (MARV); however, the mechanisms by which MARV is transmitted bat-to-bat and to other animals are unclear. Here we co-house MARV-inoculated donor ERBs with naive contact ERBs. MARV shedding is detected in oral, rectal and urine specimens from inoculated bats from 5–19 days post infection. Simultaneously, MARV is detected in oral specimens from contact bats, indicating oral exposure to the virus. In the late study phase, we provide evidence that MARV can be horizontally transmitted from inoculated to contact ERBs by finding MARV RNA in blood and oral specimens from contact bats, followed by MARV IgG antibodies in these same bats. This study demonstrates that MARV can be horizontally transmitted from inoculated to contact ERBs, thereby providing a model for filovirus maintenance in its natural reservoir host and a potential mechanism for virus spillover to other animals. PMID:28194016

  7. Understanding molecular interactions between scavenger receptor A and its natural product inhibitors through molecular modeling studies.

    PubMed

    Pagare, Piyusha P; Zaidi, Saheem A; Zhang, Xiaomei; Li, Xia; Yu, Xiaofei; Wang, Xiang-Yang; Zhang, Yan

    2017-08-16

    Scavenger receptor A (SRA), as an immune regulator, has been shown to play important roles in lipid metabolism, cardiovascular diseases, and pathogen recognition. Several natural product inhibitors of SRA have been studied for their potential application in modulating SRA functions. To understand the binding mode of these inhibitors on SRA, we conducted systematic molecular modeling studies in order to identify putative binding domain(s) that may be responsible for their recognition to the receptor as well as their inhibitory activity. Treatment of SRA with one of the natural product inhibitors, rhein, led to significant dissociation of SRA oligomers to its trimer and dimer forms, which further supported our hypothesis on their putative mechanism of action. Such information is believed to shed light on design of more potent inhibitors for the receptor in order to develop potential therapeutics through immune system modulation. Published by Elsevier Inc.

  8. Binary threshold networks as a natural null model for biological networks

    NASA Astrophysics Data System (ADS)

    Rybarsch, Matthias; Bornholdt, Stefan

    2012-08-01

    Spin models of neural networks and genetic networks are considered elegant as they are accessible to statistical mechanics tools for spin glasses and magnetic systems. However, the conventional choice of variables in spin systems may cause problems in some models when parameter choices are unrealistic from a biological perspective. Obviously, this may limit the role of a model as a template model for biological systems. Perhaps less obviously, also ensembles of random networks are affected and may exhibit different critical properties. We consider here a prototypical network model that is biologically plausible in its local mechanisms. We study a discrete dynamical network with two characteristic properties: Nodes with binary states 0 and 1, and a modified threshold function with Θ0(0)=0. We explore the critical properties of random networks of such nodes and find a critical connectivity Kc=2.0 with activity vanishing at the critical point. Finally, we observe that the present model allows a more natural implementation of recent models of budding yeast and fission yeast cell-cycle control networks.

  9. A neuromorphic model for achromatic and chromatic surface representation of natural images.

    PubMed

    Hong, Simon; Grossberg, Stephen

    2004-01-01

    This study develops a neuromorphic model of human lightness perception that is inspired by how the mammalian visual system is designed for this function. It is known that biological visual representations can adapt to a billion-fold change in luminance. How such a system determines absolute lightness under varying illumination conditions to generate a consistent interpretation of surface lightness remains an unsolved problem. Such a process, called 'anchoring' of lightness, has properties including articulation, insulation, configuration, and area effects. The model quantitatively simulates such psychophysical lightness data, as well as other data such as discounting the illuminant, and lightness constancy and contrast effects. The model retina embodies gain control at retinal photoreceptors, and spatial contrast adaptation at the negative feedback circuit between mechanisms that model the inner segment of photoreceptors and interacting horizontal cells. The model can thereby adjust its sensitivity to input intensities ranging from dim moonlight to dazzling sunlight. A new anchoring mechanism, called the Blurred-Highest-Luminance-As-White rule, helps simulate how surface lightness becomes sensitive to the spatial scale of objects in a scene. The model is also able to process natural color images under variable lighting conditions, and is compared with the popular RETINEX model.

  10. ISO reference terminology models for nursing: applicability for natural language processing of nursing narratives.

    PubMed

    Bakken, Suzanne; Hyun, Sookyung; Friedman, Carol; Johnson, Stephen B

    2005-08-01

    Natural language processing (NLP) systems have demonstrated utility in parsing narrative texts for purposes such as surveillance and decision support. However, there has been little work related to NLP of nursing narratives. The purpose of this study was to compare the semantic categories of a NLP system (Medical Language Extraction and Encoding [MedLEE] system) with the semantic domains, categories, and attributes of the International Standards Organization (ISO) reference terminology models for nursing diagnoses and nursing actions. All but two MedLEE diagnosis and procedure-related semantic categories mapped to ISO models. In some instances, we found exact correspondence between the semantic structures of MedLEE and the ISO models. In other situations (e.g. aspects of Site or Location), the ISO model was not as granular as MedLEE. For clinical procedure and non-invasive examination, two ISO nursing action model components (Action and Target) mapped to a single MedLEE semantic category. The ISO models are applicable to NLP of nursing narratives. However, the ISO models require additional specification of selected semantic categories for the abstract semantic domains in order to achieve the objective of using NLP to parse and encode data from nursing narratives. Our analysis also suggests areas for extension of MedLEE particularly in regard to represent nursing actions.

  11. Metacommunity models predict the local-regional species richness relationship in a natural system.

    PubMed

    Hugueny, Bernard; Cornell, Howard V; Harrison, Susan

    2007-07-01

    Many natural communities exhibit positive relationships between local and regional species richness (LSR-RSR relationships), which can be either linear or curvilinear. Previous models have shown that the form of this relationship depends on the relative rates of colonization and extinction and the sensitivity of these rates to competition. We use simple models to show that the LSR-RSR relationship also depends on the type of metacommunity structure (Levins-like or mainland-island), and our models generate a wider range of realistic forms than do most previous models. We parameterize and test our models with two independent data sets for Daphnia in rock pools on islands in Finland and Sweden. We find that the Levins-like model with competition correctly predicts the observed LSR-RSR relationship and provides the best fit to the average local species richness per island. Simulations show that our models are robust to relaxing our assumption of identical species properties. Our study is one of the first to make and successfully test quantitative predictions for how a widely studied community pattern, the LSR-RSR relationship, arises from metacommunity dynamics.

  12. Limit sets for natural extensions of Schelling’s segregation model

    NASA Astrophysics Data System (ADS)

    Singh, Abhinav; Vainchtein, Dmitri; Weiss, Howard

    2011-07-01

    Thomas Schelling developed an influential demographic model that illustrated how, even with relatively mild assumptions on each individual's nearest neighbor preferences, an integrated city would likely unravel to a segregated city, even if all individuals prefer integration. Individuals in Schelling's model cities are divided into two groups of equal number and each individual is "happy" or "unhappy" when the number of similar neighbors cross a simple threshold. In this manuscript we consider natural extensions of Schelling's original model to allow the two groups have different sizes and to allow different notions of happiness of an individual. We observe that differences in aggregation patterns of majority and minority groups are highly sensitive to the happiness threshold; for low threshold, the differences are small, and when the threshold is raised, striking new patterns emerge. We also observe that when individuals strongly prefer to live in integrated neighborhoods, the final states exhibit a new tessellated-like structure.

  13. Effects of a random porosity model on double diffusive natural convection in a porous medium enclosure

    SciTech Connect

    Fu, W.S.; Ke, W.W.

    2000-01-01

    A double diffusive natural convection in a rectangular enclosure filled with porous medium is investigated numerically. The distribution of porosity is based upon the random porosity model. The Darcy-Brinkman-Forchheimer model is used and the factors of heat flux, mean porosity and standard deviation are taken into consideration. The SIMPLEC method with iterative processes is adopted to solve the governing equations. The effects of the random porosity model on the distributions of local Nusselt number are remarkable and the variations of the local Nusselt number become disordered. The contribution of latent heat transfer to the total heat transfer of the high Rayleigh number is larger than that of the low Rayleigh number and the variations of the latent heat transfer are not in order.

  14. Semi-analytical models of hydroelastic sloshing impact in tanks of liquefied natural gas vessels.

    PubMed

    Ten, I; Malenica, Š; Korobkin, A

    2011-07-28

    The present paper deals with the methods for the evaluation of the hydroelastic interactions that appear during the violent sloshing impacts inside the tanks of liquefied natural gas carriers. The complexity of both the fluid flow and the structural behaviour (containment system and ship structure) does not allow for a fully consistent direct approach according to the present state of the art. Several simplifications are thus necessary in order to isolate the most dominant physical aspects and to treat them properly. In this paper, choice was made of semi-analytical modelling for the hydrodynamic part and finite-element modelling for the structural part. Depending on the impact type, different hydrodynamic models are proposed, and the basic principles of hydroelastic coupling are clearly described and validated with respect to the accuracy and convergence of the numerical results.

  15. A psycholinguistic model of natural language parsing implemented in simulated neurons.

    PubMed

    Huyck, Christian R

    2009-12-01

    A natural language parser implemented entirely in simulated neurons is described. It produces a semantic representation based on frames. It parses solely using simulated fatiguing Leaky Integrate and Fire neurons, that are a relatively accurate biological model that is simulated efficiently. The model works on discrete cycles that simulate 10 ms of biological time, so the parser has a simple mapping to psychological parsing time. Comparisons to human parsing studies show that the parser closely approximates this data. The parser makes use of Cell Assemblies and the semantics of lexical items is represented by overlapping hierarchical Cell Assemblies so that semantically related items share neurons. This semantic encoding is used to resolve prepositional phrase attachment ambiguities encountered during parsing. Consequently, the parser provides a neurally-based cognitive model of parsing.

  16. Two- and three-dimensional natural and mixed convection simulation using modular zonal models

    SciTech Connect

    Wurtz, E.; Nataf, J.M.; Winkelmann, F.

    1996-07-01

    We demonstrate the use of the zonal model approach, which is a simplified method for calculating natural and mixed convection in rooms. Zonal models use a coarse grid and use balance equations, state equations, hydrostatic pressure drop equations and power law equations of the form {ital m} = {ital C}{Delta}{sup {ital n}}. The advantage of the zonal approach and its modular implementation are discussed. The zonal model resolution of nonlinear equation systems is demonstrated for three cases: a 2-D room, a 3-D room and a pair of 3-D rooms separated by a partition with an opening. A sensitivity analysis with respect to physical parameters and grid coarseness is presented. Results are compared to computational fluid dynamics (CFD) calculations and experimental data.

  17. Evolution and non-equilibrium physics: A study of the Tangled Nature Model

    NASA Astrophysics Data System (ADS)

    Becker, Nikolaj; Sibani, Paolo

    2014-01-01

    We argue that the stochastic dynamics of interacting agents which replicate, mutate and die constitutes a non-equilibrium physical process akin to aging in complex materials. Specifically, our study uses extensive computer simulations of the Tangled Nature Model (TNM) of biological evolution to show that punctuated equilibria successively generated by the model's dynamics have increasing entropy and are separated by increasing entropic barriers. We further show that these states are organized in a hierarchy and that limiting the values of possible interactions to a finite interval leads to stationary fluctuations within a component of the latter. A coarse-grained description based on the temporal statistics of quakes, the events leading from one component of the hierarchy to the next, accounts for the logarithmic growth of the population and the decaying rate of change of macroscopic variables. Finally, we question the role of fitness in large-scale evolution models and speculate on the possible evolutionary role of rejuvenation and memory effects.

  18. A tale of twin Higgs: natural twin two Higgs doublet models

    SciTech Connect

    Yu, Jiang-Hao

    2016-12-28

    In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit Z2 breaking term. Introducing additional twin Higgs could accommodate spontaneous Z2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and Z2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit Z2 breaking, radiative Z2 breaking, tadpole-induced Z2 breaking, and quartic-induced Z2 breaking. Finally, we investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.

  19. A tale of twin Higgs: natural twin two Higgs doublet models

    DOE PAGES

    Yu, Jiang-Hao

    2016-12-28

    In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit Z2 breaking term. Introducing additional twin Higgs could accommodate spontaneous Z2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and Z2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit Z2 breaking, radiative Z2 breaking, tadpole-induced Z2 breaking, and quartic-induced Z2 breaking. Finally, we investigate the Higgs massmore » spectra and Higgs phenomenology in these scenarios.« less

  20. Spline- and wavelet-based models of neural activity in response to natural visual stimulation.

    PubMed

    Gerhard, Felipe; Szegletes, Luca

    2012-01-01

    We present a comparative study of the performance of different basis functions for the nonparametric modeling of neural activity in response to natural stimuli. Based on naturalistic video sequences, a generative model of neural activity was created using a stochastic linear-nonlinear-spiking cascade. The temporal dynamics of the spiking response is well captured with cubic splines with equidistant knot spacings. Whereas a sym4-wavelet decomposition performs competitively or only slightly worse than the spline basis, Haar wavelets (or histogram-based models) seem unsuitable for faithfully describing the temporal dynamics of the sensory neurons. This tendency was confirmed with an application to a real data set of spike trains recorded from visual cortex of the awake monkey.

  1. Isolation of chicken major histocompatibility complex class II (B-L) beta chain sequences: comparison with mammalian beta chains and expression in lymphoid organs.

    PubMed Central

    Bourlet, Y; Béhar, G; Guillemot, F; Fréchin, N; Billault, A; Chaussé, A M; Zoorob, R; Auffray, C

    1988-01-01

    By cross-hybridization in low stringency conditions, using a probe derived from an HLA-DQ beta cDNA clone, we have isolated several chicken genomic DNA clones. These clones were mapped to the major histocompatibility complex (MHC) of the chick (B complex) by virtue of their ability to detect restriction enzyme length polymorphisms between congenic lines of chicken. Evidence was obtained for the presence of at least three B-L beta genes in the chicken genome. The B-L beta genes are transcribed specifically in tissues containing cells of the B lymphocyte and myeloid lineages and expressing the B-L antigens. Exons encoding the beta 1, beta 2 and transmembrane domains of a B-L beta chain have been identified with 63, 66 and 62% similarity with the HLA-DQ beta sequence. This first isolation of an MHC class II gene outside of the mammalian class provides insight into the evolution of MHC genes based on the comparison of avian and mammalian class II beta chain amino acid and nucleotide sequences. Images PMID:2841107

  2. Stochastic model for simulating Souris River Basin precipitation, evapotranspiration, and natural streamflow

    USGS Publications Warehouse

    Kolars, Kelsey A.; Vecchia, Aldo V.; Ryberg, Karen R.

    2016-02-24

    The Souris River Basin is a 61,000-square-kilometer basin in the Provinces of Saskatchewan and Manitoba and the State of North Dakota. In May and June of 2011, record-setting rains were seen in the headwater areas of the basin. Emergency spillways of major reservoirs were discharging at full or nearly full capacity, and extensive flooding was seen in numerous downstream communities. To determine the probability of future extreme floods and droughts, the U.S. Geological Survey, in cooperation with the North Dakota State Water Commission, developed a stochastic model for simulating Souris River Basin precipitation, evapotranspiration, and natural (unregulated) streamflow. Simulations from the model can be used in future studies to simulate regulated streamflow, design levees, and other structures; and to complete economic cost/benefit analyses.Long-term climatic variability was analyzed using tree-ring chronologies to hindcast precipitation to the early 1700s and compare recent wet and dry conditions to earlier extreme conditions. The extended precipitation record was consistent with findings from the Devils Lake and Red River of the North Basins (southeast of the Souris River Basin), supporting the idea that regional climatic patterns for many centuries have consisted of alternating wet and dry climate states.A stochastic climate simulation model for precipitation, temperature, and potential evapotranspiration for the Souris River Basin was developed using recorded meteorological data and extended precipitation records provided through tree-ring analysis. A significant climate transition was seen around1970, with 1912–69 representing a dry climate state and 1970–2011 representing a wet climate state. Although there were some distinct subpatterns within the basin, the predominant differences between the two states were higher spring through early fall precipitation and higher spring potential evapotranspiration for the wet compared to the dry state.A water

  3. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    SciTech Connect

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  4. Watershed Scale Monitoring and Modeling of Natural Organic Matter (NOM) Generation and Transport

    NASA Astrophysics Data System (ADS)

    Adams, R.; Rees, P. L.; Reckhow, D. A.; Castellon, C. M.

    2006-05-01

    This study describes a coupled watershed scale monitoring campaign, laboratory study, and hydrological modeling study which has been focused on determining the sources and transport mechanisms for Natural Organic Matter (NOM), in a small, mostly forested New England watershed. For some time, the state conservation authorities and a large metropolitan water authority have been concerned that the level of naturally-occurring disinfection byproducts in drinking water supplied by a large surface water reservoir (Watchusett Reservoir, MA) have been increasing over time. The resulting study has attempted to investigate how these compounds, which are mostly formed by the chlorination process at the water treatment plant, are related to NOM precursor compounds which are generated from organic matter and transported by runoff processes in the watershed of the Watchusett Reservoir. The laboratory study measures disinfection byproduct formation potential (DBPFP) through chlorination of raw water samples obtained through field monitoring. Samples are analysed for trihalomethanes (THMs), and haloacetic acids (HAAs). Samples are also analysed for dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV254). The samples have been collected from as many components of the hydrological cycle as possible in one of the subcatchments of Watchusett Reservoir (Stillwater River). To date the samples include, stream runoff, water impounded naturally in small ponds by beaver dams, rainfall, snow, throughfall (drainage from tree canopies) and samples pumped from shallow suction lysimeters which were installed to monitor soil water in the riparian zone. The current monitoring program began in late-Summer 2005, however infrequent stream samples are available dating back to 2000 from an earlier research project and water quality monitoring by various regulatory authorities. The monitoring program has been designed to capture as much seasonal variation in water chemistry as

  5. Existence of Natural Frequencies of Systems with Artificial Restraints and Their Convergence in Asymptotic Modelling

    NASA Astrophysics Data System (ADS)

    Ilanko, S.

    2002-08-01

    A major limitation of the Rayleigh-Ritz method for determining the natural frequencies of a system is the need to choose admissible functions that do not violate the geometric constraints of that system (Courant 1943 Bulletin of the American Mathematical Society49, 1-23). Several researchers have attempted to overcome this problem by asymptotically modelling the rigid constraints with artificial (imaginary) restraints of very large stiffness (Courant 1943 Bulletin of the American Mathematical Society49 , 1-23; Warburton and Edney 1984 Journal of Sound and Vibration95, 537-552; Gorman 1989 Journal of Applied Mechanics56, 893-899; Kim et al. 1990 Journal of Sound and Vibration143, 379-394; Yuan and Dickinson 1992 Journal of Sound and Vibration153, 203-216; Yuan and Dickinson 1992 Journal of Sound and Vibration159, 39-55; Cheng and Nicolas 1992 Journal of Sound and Vibration155, 231-247; Yuan and Dickinson 1994 Computers and Structures53 , 327-334; Lee and Ng 1994 Applied Acoustics42, 151-163; Amabili and Garziera 1999 Journal of Sound and Vibration224, 519-539; Amabili and Garziera 2000 Journal of Fluids and Structures14, 669-690). While the numerical results thus obtained for the systems considered in the literature were in close agreement with exact values for the natural frequencies corresponding to the first few modes, sample calculations show that the error introduced by the asymptotic modelling increases with mode number and therefore to obtain accurate results for higher modes the magnitude of stiffness should also be increased. In any event, the error due to the asymptotic modelling would remain uncertain, except when the correct frequency values are known. However, the use of artificial restraints with negative stiffness, a new concept which was introduced in a recent publication (Ilanko and Dickinson 1999 Journal of Sound and Vibration219, 370-378) paves the way for estimating the error due to asymptotic modelling. This is possible since in this work, the

  6. The dynamic nature of knowledge: insights from a dynamic field model of children's novel noun generalization

    PubMed Central

    Samuelson, Larissa K.; Schutte, Anne R.; Horst, Jessica S.

    2011-01-01

    The present paper examines the tie between knowledge and behavior in a noun generalization context. An experiment directly comparing noun generalizations of children at the same point in development in forced choice and yes/no tasks reveals task-specific differences in the way children's knowledge of nominal categories is brought to bear in a moment. To understand the cognitive system that produced these differences, the real-time decision processes in these tasks were instantiated in a dynamic field model. The model captures both qualitative and quantitative differences in performance across tasks and reveals constraints on the nature of children's accumulated knowledge. Additional simulations of developmental change in the yes/no task between 2 and 4 years of age illustrate how changes in children's representations translate into developmental changes in behavior. Together, the empirical data and model demonstrate the dynamic nature of knowledge and are consistent with the perspective that knowledge cannot be separated from the task-specific processes that create behavior in the moment. PMID:19131050

  7. Models of natural fracture connectivity -- Implications for reservoir permeability. Final report

    SciTech Connect

    Pollard, D.D.; Aydin, A.

    1994-11-14

    Fluid flow through fracture networks in a rock mass depends strongly on the nature of connections between fracture segments and between individual fractures. Therefore the objective of this research project is to develop three dimensional models for natural fracture connectivity using an integrated field, laboratory, and theoretical methodology. The geometric models the authors have developed are based on detailed field mapping and observations from outcrops of both massive and layered sedimentary rocks, typical of producing oil and gas reservoirs, or of aquifers. Furthermore, the have used computer simulations and laboratory experiments to investigate the physical mechanisms responsible for fracture connectivity (or lack thereof) as single and multiple sets of fractures evolve. The computer models are based on fracture mechanics principles and the laboratory experiments utilize layered composite materials analogous to sedimentary sequences. By identifying the physical mechanisms of connectivity they can relate the degree of connectivity to the geometry, state of stress, and material properties of the reservoir rocks and, in turn, be in a position to evaluate the influence of these factors on fracture permeability.

  8. Collagen and keratin polypeptide models for assessing the natural and artificial protein decay of organic materials.

    PubMed

    Fotou, Evmorfia; Sakarellos-Daitsiotis, Maria; Ioakeimoglou, Eleni; Tziamourani, Eleni; Malea, Ekaterini; Panayiaris, George; Panou-Pomonis, Eugenia

    2016-11-01

    Among the materials constituting the natural and cultural heritage, organic materials of proteinaceous origin as bone (collagen), parchment and woolen textiles (keratin) are the most susceptible to damage and decay because of their exposure to air pollution, inappropriate values of ambient temperature, humidity and light. Aiming at contributing to the development of a reliable and reproducible immunoassay for the evaluation of collagen and keratin decay, three polypeptide models of these proteins were designed, synthesized and studied. Polypeptide [Pro-Ser(OBzl)-Gly]n incorporates the typical motif Pro-X-Gly of collagen; polypeptide [Pro-Cys(Acm)-Gly]n is a model of the C-terminal domain of type I keratin, corresponding to the repeating unit Pro-Cys-X of keratin, while polypeptide Ac-YRSGGGFGYRSGGGFGYRS-βAla-NH2 encloses the characteristic repeating sequence GGGFGYRS of the N-terminal part of Type II keratin. These polypeptides may be considered as simplified models that mimic fragments of collagen and keratin resulting from artificial and natural ageing or decay. It is concluded that high recognition of anti-polypeptide antibodies, produced after immunizations, by the bone, parchment and textile samples is indicative of high deterioration, while high anti-collagen or anti-keratin recognition is indicative of low deterioration. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  9. Fractional brownian functions as mathematical models of natural rhythm in architecture.

    PubMed

    Cirovic, Ivana M

    2014-10-01

    Carl Bovill suggested and described a method of generating rhythm in architecture with the help of fractional Brownian functions, as they are mathematical models of natural rhythm. A relationship established in the stated procedure between fractional Brownian functions as models of rhythm, and the observed group of architectural elements, is recognized as an analogical relationship, and the procedure of generating rhythm as a process of analogical transfer from the natural domain to the architectural domain. Since analogical transfer implies relational similarity of two domains, and the establishment of one-to-one correspondence, this paper is trying to determine under which conditions such correspondence could be established. For example, if the values of the observed visual feature of architectural elements are not similar to each other in a way in which they can form a monotonically increasing, or a monotonically decreasing bounded sequence, then the structural alignment and the one-to-one correspondence with a single fractional Brownian function cannot be established, hence, this function is deemed inappropriate as a model for the architectural rhythm. In this case we propose overlapping of two or more functions, so that each of them is an analog for one subset of mutually similar values of the visual feature of architectural elements.

  10. Natural Organic Matter Transport Modeling with a Continuous Time Random Walk Approach

    PubMed Central

    McInnis, Daniel P.; Bolster, Diogo; Maurice, Patricia A.

    2014-01-01

    Abstract In transport experiments through columns packed with naturally Fe/Al oxide-coated quartz sand, breakthrough curves (BTCs) of natural organic matter (NOM) displayed strong and persistent power law tailing that could not be described by the classical advection–dispersion equation. Tailing was not observed in BTCs for a nonreactive tracer (sulforhodamine B); therefore, the anomalous transport is attributed to diverse adsorptive behavior of the polydisperse NOM sample rather than to physical heterogeneity of the porous medium. NOM BTC tailing became more pronounced with decreases in pH and increases in ionic strength, conditions previously shown to be associated with enhanced preferential adsorption of intermediate to high molecular weight NOM components. Drawing from previous work on anomalous solute transport, we develop an approach to model NOM transport within the framework of a continuous time random walk (CTRW) and show that under all conditions examined, the CTRW model is able to capture tailing of NOM BTCs by accounting for differences in transport rates of NOM fractions through a distribution of effective retardation factors. These results demonstrate the importance of considering effects of adsorptive fractionation on NOM mobility, and illustrate the ability of the CTRW model to describe transport of a multicomponent solute. PMID:24596449

  11. Translational pain assessment: could natural animal models be the missing link?

    PubMed

    Klinck, Mary P; Mogil, Jeffrey S; Moreau, Maxim; Lascelles, B Duncan X; Flecknell, Paul A; Poitte, Thierry; Troncy, Eric

    2017-09-01

    Failure of analgesic drugs in clinical development is common. Along with the current "reproducibility crisis" in pain research, this has led some to question the use of animal models. Experimental models tend to comprise genetically homogeneous groups of young, male rodents in restricted and unvarying environments, and pain-producing assays that may not closely mimic the natural condition of interest. In addition, typical experimental outcome measures using thresholds or latencies for withdrawal may not adequately reflect clinical pain phenomena pertinent to human patients. It has been suggested that naturally occurring disease in veterinary patients may provide more valid models for the study of painful disease. Many painful conditions in animals resemble those in people. Like humans, veterinary patients are genetically diverse, often live to old age, and enjoy a complex environment, often the same as their owners. There is increasing interest in the development and validation of outcome measures for detecting pain in veterinary patients; these include objective (eg, locomotor activity monitoring, kinetic evaluation, quantitative sensory testing, and bioimaging) and subjective (eg, pain scales and quality of life scales) measures. Veterinary subject diversity, pathophysiological similarities to humans, and diverse outcome measures could yield better generalizability of findings and improved translation potential, potentially benefiting both humans and animals. The Comparative Oncology Trial Consortium in dogs has pawed the way for translational research, surmounting the challenges inherent in veterinary clinical trials. This review describes numerous conditions similarly applicable to pain research, with potential mutual benefits for human and veterinary clinicians, and their respective patients.

  12. A systems approach to model natural variation in reactive properties of bacterial ribosomes

    PubMed Central

    Jackson, Julius H; Schmidt, Thomas M; Herring, Patricia A

    2008-01-01

    Background Natural variation in protein output from translation in bacteria and archaea may be an organism-specific property of the ribosome. This paper adopts a systems approach to model the protein output as a measure of specific ribosome reactive properties in a ribosome-mediated translation apparatus. We use the steady-state assumption to define a transition state complex for the ribosome, coupled with mRNA, tRNA, amino acids and reaction factors, as a subsystem that allows a focus on the completed translational output as a measure of specific properties of the ribosome. Results In analogy to the steady-state reaction of an enzyme complex, we propose a steady-state translation complex for mRNA from any gene, and derive a maximum specific translation activity, Ta(max), as a property of the ribosomal reaction complex. Ta(max) has units of a-protein output per time per a-specific mRNA. A related property of the ribosome, T˜a(max⁡), has units of a-protein per time per total RNA with the relationship T˜a(max⁡) = ρa Ta(max), where ρa represents the fraction of total RNA committed to translation output of Pa from gene a message. Ta(max) as a ribosome property is analogous to kcat for a purified enzyme, and T˜a(max⁡) is analogous to enzyme specific activity in a crude extract. Conclusion Analogy to an enzyme reaction complex led us to a ribosome reaction model for measuring specific translation activity of a bacterial ribosome. We propose to use this model to design experimental tests of our hypothesis that specific translation activity is a ribosomal property that is subject to natural variation and natural selection much like Vmax and Km for any specific enzyme. PMID:18620602

  13. Towards modelling flood protection investment as a coupled human and natural system

    NASA Astrophysics Data System (ADS)

    O'Connell, P. E.; O'Donnell, G.

    2013-06-01

    Due to a number of recent high profile flood events and the apparent threat from global warming, governments and their agencies are under pressure to make proactive investments to protect people living in floodplains. However, adopting a proactive approach as a universal strategy is not affordable. It has been argued that delaying expensive and essentially irreversible capital decisions could be a prudent strategy in situations with high future uncertainty. This paper firstly uses Monte Carlo simulation to explore the performance of proactive and reactive investment strategies using a rational cost-benefit approach in a natural system with varying levels of persistence/interannual variability in Annual Maximum Floods. It is found that, as persistence increases, there is a change in investment strategy optimality from proactive to reactive. This could have implications for investment strategies under the increasingly variable climate that is expected with global warming. As part of the emerging holistic approaches to flood risk management, there is increasing emphasis on stakeholder participation in determining where and when flood protection investments are made, and so flood risk management is becoming more people-centred. As a consequence, multiple actors are involved in the decision-making process, and the social sciences are assuming an increasingly important role in flood risk management. There is a need for modelling approaches which can couple the natural and human system elements. It is proposed that Coupled Human and Natural System (CHANS) modelling could play an important role in understanding the motivations, actions and influence of citizens and institutions and how these impact on the effective delivery of flood protection investment. A framework for using Agent Based Modelling of human activities leading to flood investments is outlined, and some of the challenges associated with implementation are discussed.

  14. Towards modelling flood protection investment as a coupled human and natural system

    NASA Astrophysics Data System (ADS)

    O'Connell, P. E.; O'Donnell, G.

    2014-01-01

    Due to a number of recent high-profile flood events and the apparent threat from global warming, governments and their agencies are under pressure to make proactive investments to protect people living in floodplains. However, adopting a proactive approach as a universal strategy is not affordable. It has been argued that delaying expensive and essentially irreversible capital decisions could be a prudent strategy in situations with high future uncertainty. This paper firstly uses Monte Carlo simulation to explore the performance of proactive and reactive investment strategies using a rational cost-benefit approach in a natural system with varying levels of persistence/interannual variability in annual maximum floods. It is found that, as persistence increases, there is a change in investment strategy optimality from proactive to reactive. This could have implications for investment strategies under the increasingly variable climate that is expected with global warming. As part of the emerging holistic approaches to flood risk management, there is increasing emphasis on stakeholder participation in determining where and when flood protection investments are made, and so flood risk management is becoming more people-centred. As a consequence, multiple actors are involved in the decision-making process, and the social sciences are assuming an increasingly important role in flood risk management. There is a need for modelling approaches which can couple the natural and human system elements. It is proposed that coupled human and natural system (CHANS) modelling could play an important role in understanding the motivations, actions and influence of citizens and institutions and how these impact on the effective delivery of flood protection investment. A framework for using agent-based modelling of human activities leading to flood investments is outlined, and some of the challenges associated with implementation are discussed.

  15. Experimental and modeling analysis of coupled non-Fickian transport and sorption in natural soils

    NASA Astrophysics Data System (ADS)

    Rubin, S.; Berkowitz, B.

    2011-12-01

    We present experimental breakthrough curve (BTC) data and a modeling investigation of conservative and sorbing tracer transport in natural soils. By analyzing the data using the continuous time random walk (CTRW) model, we probe the traditional approach of using conservative tracer model parameters as a basis for quantifying the transport of sorbing solutes in the same domain. Many known contaminants in groundwater are sorbed to the host solid porous medium, to varying extents, while being transported; this enhances the long tailing of BTCs which already arise because of the inherent non-Fickian nature of the transport. The CTRW framework has been shown to account very well for non-Fickian conservative (nonsorbing) transport. Here, we examine two BTC data sets in laboratory columns packed with natural soils; the first (previously published) comprises transport of (conservative) bromide and (sorbing) atrazine tracers, while the second comprises new data with bromide and tribromoneopentyl alcohol (TBNPA), a common flame retardant, as a sorbing solute. We find that the transport behavior of bromide is non-Fickian in all cases, which is caused by the heterogeneity of the soil. Analysis of the relation between the non-Fickian transport of the conservative and sorbing tracers demonstrates the coupling between transport and adsorption/desorption, and the result that transport parameters (average velocity and dispersion coefficient) calibrated for the conservative tracer parameters are not applicable to the transport of reactive tracers. Our analyses further confirm the relevance and applicability of CTRW theory to the case of laboratory-scale observations of sorbing solutes.

  16. New prognostic model for extranodal natural killer/T cell lymphoma, nasal type.

    PubMed

    Cai, Qingqing; Luo, Xiaolin; Zhang, Guanrong; Huang, Huiqiang; Huang, Hui; Lin, Tongyu; Jiang, Wenqi; Xia, Zhongjun; Young, Ken H

    2014-09-01

    Extranodal natural killer/T cell lymphoma, nasal type (ENKTL) is an aggressive disease with a poor prognosis, requiring risk stratification in affected patients. We designed a new prognostic model specifically for ENKTL to identify high-risk patients who need more aggressive therapy. We retrospectively reviewed 158 patients who were newly diagnosed with ENKTL. The estimated 5-year overall survival rate was 39.4 %. Independent prognostic factors included total protein (TP) <60 g/L, fasting blood glucose (FBG) >100 mg/dL, and Korean Prognostic Index (KPI) score ≥2. We constructed a new prognostic model by combining these prognostic factors: group 1 (64 cases (41.0 %)), no adverse factors; group 2 (58 cases (37.2 %)), one adverse factor; and group 3 (34 cases (21.8 %)), two or three adverse factors. The 5-year overall survival (OS) rates of these groups were 66.7, 23.0, and 5.9 %, respectively (p < 0.001). Our new prognostic model had a better prognostic value than did the KPI model alone (p < 0.001). Our proposed prognostic model for ENKTL, including the newly identified prognostic indicators, TP and FBG, demonstrated a balanced distribution of patients into different risk groups with better prognostic discrimination compared with the KPI model alone.

  17. The Behaviour of Naturally Debonded Composites Due to Bending Using a Meso-Level Model

    NASA Astrophysics Data System (ADS)

    Lord, C. E.; Rongong, J. A.; Hodzic, A.

    2012-06-01

    Numerical simulations and analytical models are increasingly being sought for the design and behaviour prediction of composite materials. The use of high-performance composite materials is growing in both civilian and defence related applications. With this growth comes the necessity to understand and predict how these new materials will behave under their exposed environments. In this study, the displacement behaviour of naturally debonded composites under out-of-plane bending conditions has been investigated. An analytical approach has been developed to predict the displacement response behaviour. The analytical model supports multi-layered composites with full and partial delaminations. The model can be used to extract bulk effective material properties in which can be represented, later, as an ESL (Equivalent Single Layer). The friction between each of the layers is included in the analytical model and is shown to have distinct behaviour for these types of composites. Acceptable agreement was observed between the model predictions, the ANSYS finite element model, and the experiments.

  18. Impact of a refined airborne LiDAR stochastic model for natural hazard applications

    NASA Astrophysics Data System (ADS)

    Glennie, C. L.; Bolkas, D.; Fotopoulos, G.

    2016-12-01

    Airborne Light Detection and Ranging (LiDAR) is often employed to derive multi-temporal Digital Elevation Models (DEMs), that are used to estimate vertical displacement resulting from natural hazards such as landslides, rockfalls and erosion. Vertical displacements are estimated by computing the difference between two DEMs separated by a specified time period and applying a threshold to remove the inherent noise. Thus, reliable information about the accuracy of DEMs is essential. The assessment of airborne LiDAR errors is typically based on (i) independent ground control points (ii) forward error propagation utilizing the LiDAR geo-referencing equation. The latter approach is dependent on the stochastic model information of the LiDAR measurements. Furthermore, it provides the user with point-by-point accuracy estimation. In this study, a refined stochastic model is obtained through variance component estimation (VCE) for a dataset in Houston, Texas. Results show that initial stochastic information was optimistic by 35% for both horizontal coordinates and ellipsoidal heights. To assess the impact of a refined stochastic model, surface displacement simulations are evaluated. The simulations include scenarios with topographic slopes that vary from 10º to 60º, and vertical displacement of ±1 to ±5 m. Results highlight the cases where a reliable stochastic model is important. A refined stochastic model can be used in practical applications for determining appropriate noise thresholds in vertical displacement, improve quantitative analysis, and enhance relevant decision-making.

  19. Application of atomic force microscopy to the study of natural and model soil particles.

    PubMed

    Cheng, S; Bryant, R; Doerr, S H; Rhodri Williams, P; Wright, C J

    2008-09-01

    The structure and surface chemistry of soil particles has extensive impact on many bulk scale properties and processes of soil systems and consequently the environments that they support. There are a number of physiochemical mechanisms that operate at the nanoscale which affect the soil's capability to maintain native vegetation and crops; this includes soil hydrophobicity and the soil's capacity to hold water and nutrients. The present study used atomic force microscopy in a novel approach to provide unique insight into the nanoscale properties of natural soil particles that control the physiochemical interaction of material within the soil column. There have been few atomic force microscopy studies of soil, perhaps a reflection of the heterogeneous nature of the system. The present study adopted an imaging and force measurement research strategy that accounted for the heterogeneity and used model systems to aid interpretation. The surface roughness of natural soil particles increased with depth in the soil column a consequence of the attachment of organic material within the crevices of the soil particles. The roughness root mean square calculated from ten 25 microm(2) images for five different soil particles from a Netherlands soil was 53.0 nm, 68.0 nm, 92.2 nm and 106.4 nm for the respective soil depths of 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm. A novel analysis method of atomic force microscopy phase images based on phase angle distribution across a surface was used to interpret the nanoscale distribution of organic material attached to natural and model soil particles. Phase angle distributions obtained from phase images of model surfaces were found to be bimodal, indicating multiple layers of material, which changed with the concentration of adsorbed humic acid. Phase angle distributions obtained from phase images of natural soil particles indicated a trend of decreasing surface coverage with increasing depth in the soil column. This was consistent with

  20. Organic complexation of rare earth elements in natural waters: Evaluating model calculations from ultrafiltration data

    NASA Astrophysics Data System (ADS)

    Pourret, Olivier; Davranche, Mélanie; Gruau, Gérard; Dia, Aline

    2007-06-01

    The Stockholm Humic Model (SHM) and Humic Ion-Binding Models V and VI were compared for their ability to predict the role of dissolved organic matter (DOM) in the speciation of rare earth elements (REE) in natural waters. Unlike Models V and VI, SHM is part of a speciation code that also allows us to consider dissolution/precipitation, sorption/desorption and oxidation/reduction reactions. In this context, it is particularly interesting to test the performance of SHM. The REE specific equilibrium constants required by the speciation models were estimated using linear free-energy relationships (LFER) between the first hydrolysis constants and the stability constants for REE complexation with lactic and acetic acid. Three datasets were used for the purpose of comparison: (i) World Average River Water (Dissolved Organic Carbon (DOC) = 5 mg L -1), previously investigated using Model V, was reinvestigated using SHM and Model VI; (ii) two natural organic-rich waters (DOC = 18-24 mg L -1), whose REE speciation has already been determined with both Model V and ultrafiltration studies, were also reinvestigated using SHM and Model VI; finally, (iii) new ultrafiltration experiments were carried out on samples of circumneutral-pH (pH 6.2-7.1), organic-rich (DOC = 7-20 mg L -1) groundwaters from the Kervidy-Naizin and Petit-Hermitage catchments, western France. The results were then compared with speciation predictions provided by Model VI and SHM, successively. When applied to World Average River Water, both Model VI and SHM yield comparable results, confirming the earlier finding that a large fraction of the dissolved REE in rivers occurs as organic complexes This implies that the two models are equally valid for calculating REE speciation in low-DOC waters at circumneutral-pH. The two models also successfully reproduced ultrafiltration results obtained for DOC-rich acidic groundwaters and river waters. By contrast, the two models yielded different results when compared to