Modeling Nucleon Generalized Parton Distributions
Radyushkin, Anatoly V.
2013-05-01
We discuss building models for nucleon generalized parton distributions (GPDs) H and E that are based on the formalism of double distributions (DDs). We find that the usual "DD+D-term'' construction should be amended by an extra term, generated by GPD E(x,\\xi). Unlike the $D$-term, this function has support in the whole -1 < x< 1 region, and in general does not vanish at the border points|x|=\\xi.
Modeling Nucleon Generalized Parton Distributions
Radyushkin, Anatoly V.
2013-05-01
We discuss building models for nucleon generalized parton distributions (GPDs) H and E that are based on the formalism of double distributions (DDs). We found that the usual "DD+D-term" construction should be amended by an extra term, xiE^1_+ (x,xi) built from the alpha/Beta moment of the DD e(Beta,alpha) that generates GPD E(x,xi). Unlike the D-term, this function has support in the whole -1< x<1 region, and in general does not vanish at the border points |x|=xi.
NASA Astrophysics Data System (ADS)
Dean, David Jarvis
1991-02-01
The purpose of this dissertation is to develop a dynamical 3 + 1-dimensional model of interacting hadrons in relativistic collisions. The model incorporates the valence quark structure functions of the hadrons into the dynamical Nambu-Goto string picture. The nucleon is viewed as an ensemble average of various initial string configurations such that the flavor averaged valence quark structure function is reproduced. A stochastic decay mechanism is also developed and applied to string fragmentation (hadronization). The interaction e^+e^-togamma ^{*}to q| q is studied at energies from sqrt{s} = 14 to 30 GeV, and decay parameters are chosen such that the correct experimental multiplicity of particles is obtained. Transverse momentum production is obtained by dynamically generating q| q pairs according to a phenomenological momentum distribution. The interaction mechanism between two colliding nucleons is based on a quark-quark scattering and exchange. The quark scattering cross section is parameterized to reproduce the experimental results. The interactions coupled with the hadronization mechanism successfully reproduce many of the observed inclusive distributions. These include, the charged particle, rapidity, scaled parallel momentum, and p_| distributions. At the present stage of numerical calculations p_ | < 1.1 GeV region has been studied. The model interaction is capable of investigating higher p_| values, which require better statistics and more computing time. Using this interaction, pp collisions at sqrt{s} = 19.4 and 53 GeV are studied and reasonable fits to data are obtained. A further application of the model involves the study of the nuclear attenuation effects observed in e^-A when compared to e ^-p collision experiments. These effects are also observed in the string-parton calculation. At energies of v < 10 GeV the nuclear medium influences the hadronization process. At higher energies the effect is negligible.
Modeling the Pion Generalized Parton Distribution
NASA Astrophysics Data System (ADS)
Mezrag, C.
2016-02-01
We compute the pion Generalized Parton Distribution (GPD) in a valence dressed quarks approach. We model the Mellin moments of the GPD using Ansätze for Green functions inspired by the numerical solutions of the Dyson-Schwinger Equations (DSE) and the Bethe-Salpeter Equation (BSE). Then, the GPD is reconstructed from its Mellin moment using the Double Distribution (DD) formalism. The agreement with available experimental data is very good.
The partonic interpretation of reggeon theory models
NASA Astrophysics Data System (ADS)
Boreskov, K. G.; Kaidalov, A. B.; Khoze, V. A.; Martin, A. D.; Ryskin, M. G.
2005-12-01
We review the physical content of the two simplest models of reggeon field theory: namely the eikonal and the Schwimmer models. The AGK cutting rules are used to obtain the inclusive, the inelastic and the diffractive cross sections. The system of non-linear equations for these cross sections is written down and analytic expressions for its solution are obtained. We derive the rapidity gap dependence of the differential cross sections for diffractive dissociation in the Schwimmer model and in its eikonalized extension. The results are interpreted from the partonic viewpoint of the interaction at high energies.
The Polarized TMDs in the covariant parton model approach
A.V. Efremov, P. Schweitzer, O.V. Teryaev, P. Zavada
2011-05-01
We derive relations between polarized transverse momentum dependent distribution functions (TMDs) and the usual parton distribution functions (PDFs) in the 3D covariant parton model, which follow from Lorentz invariance and the assumption of a rotationally symmetric distribution of parton momenta in the nucleon rest frame. Using the known PDF $g_{1}^{q}(x)$ as input we predict the $x$- and $\\mathbf{p}_{T}$-dependence of all polarized twist-2 naively time-reversal even (T-even) TMDs.
New model for nucleon generalized parton distributions
Radyushkin, Anatoly V.
2014-01-01
We describe a new type of models for nucleon generalized parton distributions (GPDs) H and E. They are heavily based on the fact nucleon GPDs require to use two forms of double distribution (DD) representations. The outcome of the new treatment is that the usual DD+D-term construction should be amended by an extra term, {xi} E{sub +}{sup 1} (x,{xi}) which has the DD structure {alpha}/{beta} e({beta},{alpha}, with e({beta},{alpha}) being the DD that generates GPD E(x,{xi}). We found that this function, unlike the D-term, has support in the whole -1 <= x <= 1 region. Furthermore, it does not vanish at the border points |x|={xi}.
Generalized Valon Model for Double Parton Distributions
NASA Astrophysics Data System (ADS)
Broniowski, Wojciech; Ruiz Arriola, Enrique; Golec-Biernat, Krzysztof
2016-06-01
We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.
Generalized Valon Model for Double Parton Distributions
NASA Astrophysics Data System (ADS)
Broniowski, Wojciech; Ruiz Arriola, Enrique; Golec-Biernat, Krzysztof
2016-03-01
We show how the double parton distributions may be obtained consistently from the many-body light-cone wave functions. We illustrate the method on the example of the pion with two Fock components. The procedure, by construction, satisfies the Gaunt-Stirling sum rules. The resulting single parton distributions of valence quarks and gluons are consistent with a phenomenological parametrization at a low scale.
A.V. Efremov, P. Schweitzer, O.V. Teryaev, P. Zavada
2011-03-01
We derive relations between transverse momentum dependent distribution functions (TMDs) and the usual parton distribution functions (PDFs) in the 3D covariant parton model, which follow from Lorentz invariance and the assumption of a rotationally symmetric distribution of parton momenta in the nucleon rest frame. Using the known PDFs f_1(x) and g_1(x) as input we predict the x- and pT-dependence of all twist-2 T-even TMDs.
Efremov, A. V.; Teryaev, O. V.; Schweitzer, P.; Zavada, P.
2011-03-01
We derive relations between transverse momentum dependent distribution functions and the usual parton distribution functions in the 3D covariant parton model, which follow from Lorentz invariance and the assumption of a rotationally symmetric distribution of parton momenta in the nucleon rest frame. Using the known parton distribution functions f{sub 1}{sup a}(x) and g{sub 1}{sup a}(x) as input we predict the x- and p{sub T}-dependence of all twist-2 T-even transverse momentum dependent distribution functions.
Nonperturbative approach to the parton model
NASA Astrophysics Data System (ADS)
Simonov, Yu. A.
2016-02-01
In this paper, the nonperturbative parton distributions, obtained from the Lorentz contracted wave functions, are analyzed in the formalism of many-particle Fock components and their properties are compared to the standard perturbative distributions. We show that the collinear and IR divergencies specific for perturbative evolution treatment are absent in the nonperturbative version, however for large momenta pi2 ≫ σ (string tension), the bremsstrahlung kinematics is restored. A preliminary discussion of possible nonperturbative effects in DIS and high energy scattering is given, including in particular a possible role of multihybrid states in creating ridge-type effects.
Independent pair parton interactions model of hadron interactions
NASA Astrophysics Data System (ADS)
Dremin, I. M.; Nechitailo, V. A.
2004-08-01
A model of independent pair parton interactions is proposed, according to which hadron interactions are represented by a set of independent binary parton collisions. The final multiplicity distribution is described by a convolution of the negative binomial distributions in each of the partonic collisions. As a result, it is given by a weighted sum of negative binomial distributions with parameters multiplied by the number of active pairs. Its shape and moments are considered. Experimental data on multiplicity distributions in high energy pp¯ processes are well fitted by these distributions. Predictions for the CERN Large Hadron Collider and higher energies are presented. The difference between e+e- and pp¯ processes is discussed.
Backward dilepton production in color dipole and parton models
Gay Ducati, Maria Beatriz; Graeve de Oliveira, Emmanuel
2010-03-01
The Drell-Yan dilepton production at backward rapidities is studied in proton-nucleus collisions at Relativistic Heavy Ion Collider and LHC energies by comparing two different approaches: the k{sub T} factorization at next-to-leading order with intrinsic transverse momentum and the same process formulated in the target rest frame, i.e., the color dipole approach. Our results are expressed in terms of the ratio between p(d)-A and p-p collisions as a function of transverse momentum and rapidity. Three nuclear parton distribution functions are used: EKS (Eskola, Kolhinen, and Ruuskanen), EPS08, and EPS09 and, in both approaches, dileptons show sensitivity to nuclear effects, specially regarding the intrinsic transverse momentum. Also, there is room to discriminate between formalisms: the color dipole approach lacks soft effects introduced by the intrinsic k{sub T}. Geometric scaling GBW (Golec-Biernat and Wusthoff) and BUW (Boer, Utermann, and Wessels) color dipole cross section models and also a DHJ (Dumitru, Hayashigaki, and Jalilian-Marian) model, which breaks geometric scaling, are used. No change in the ratio between collisions is observed, showing that this observable is not changed by the particular shape of the color dipole cross section. Furthermore, our k{sub T} factorization results are compared with color glass condensate results at forward rapidities: the results agree at Relativistic Heavy Ion Collider although disagree at LHC, mainly due to the different behavior of target gluon and quark shadowing.
Diffraction scattering and the parton model in QCD
White, A.
1985-01-01
Arguments are presented that the validity of the parton model for hadron scattering in QCD is directly related to the occurrence of the Critical Pomeron description of diffraction scattering. An attractive route suggested for Electroweak and Grand Unification is also briefly described.
Small-x parton distributions of large hadronic targets
NASA Astrophysics Data System (ADS)
Hebecker, A.; Weigert, H.
1998-07-01
A simple and intuitive calculation, based on the semiclassical approximation, demonstrates how the large size of a hadronic target introduces a new perturbative scale into the process of small-x deep inelastic scattering. The above calculation, which is performed in the target rest frame, is compared to the McLerran-Venugopalan model for scattering off large nuclei, which has first highlighted this effect in the infinite momentum frame. It is shown that the two approaches, i.e., the rest frame based semiclassical calculation and the infinite momentum frame based McLerran-Venugopalan approach are quantitatively consistent.
Projective symmetry of partons in Kitaev's honeycomb model
NASA Astrophysics Data System (ADS)
Mellado, Paula
2015-03-01
Low-energy states of quantum spin liquids are thought to involve partons living in a gauge-field background. We study the spectrum of Majorana fermions of Kitaev's honeycomb model on spherical clusters. The gauge field endows the partons with half-integer orbital angular momenta. As a consequence, the multiplicities reflect not the point-group symmetries of the cluster, but rather its projective symmetries, operations combining physical and gauge transformations. The projective symmetry group of the ground state is the double cover of the point group. We acknowledge Fondecyt under Grant No. 11121397, Conicyt under Grant No. 79112004, and the Simons Foundation (P.M.); the Max Planck Society and the Alexander von Humboldt Foundation (O.P.); and the US DOE Grant No. DE-FG02-08ER46544 (O.T.).
A check-up for the statistical Parton model
NASA Astrophysics Data System (ADS)
Buccella, Franco; Sohaily, Sozha
2015-11-01
We compare the Parton distributions deduced in the framework of a quantum statistical approach for both the longitudinal and transverse degrees of freedom with the unpolarized distributions measured at HERA and with the polarized ones proposed in a previous paper, which have been shown to be in very good agreement also with the results of experiments performed after that proposal. The agreement with HERA data in correspondence to very similar values for the “temperature” and the “potentials” found in the previous work gives a robust confirm of the statistical model. The unpolarized distributions are compared also with the result of NNPDF. The free parameters are fixed mainly by data in the range (0.1, 0.5) for the x variable, where the valence Partons dominate, and in the small x region for the diffractive contribution. This feature makes the parametrization proposed here very attractive.
Efremov, A. V.; Teryaev, O. V.; Schweitzer, P.; Zavada, P.
2009-07-01
Transverse parton momentum dependent distribution functions (TMDs) of the nucleon are studied in a covariant model, which describes the intrinsic motion of partons in terms of a covariant momentum distribution. The consistency of the approach is demonstrated, and model relations among TMDs are studied. As a by-product it is shown how the approach allows to formulate the nonrelativistic limit.
Frederico, T.; Pace, E.; Pasquini, B.; Salme, G.
2010-08-05
Longitudinal and transverse parton distributions for pion and nucleon are calculated from hadron vertexes obtained by a study of form factors within relativistic quark models. The relevance of the one-gluon-exchange dominance at short range for the behavior of the form factors at large momentum transfer and of the parton distributions at the end points is stressed.
Comparing multiparticle production within a two-component dual parton model with collider data
Hahn, K.; Ranft, J. )
1990-03-01
The dual parton model (DPM) is very successful in describing hadronic multiparticle production. The version of DPM presented includes both soft and hard mechanisms. The hard component is described according to the lowest-order perturbative QCD--parton-model cross section. The model is formulated in the form of a Monte Carlo event generator. Results obtained with this event generator are compared with data on inclusive reactions in the TeV energy range of the CERN and Fermilab hadron colliders.
Parton model for hA and AA collisions at high energies
NASA Astrophysics Data System (ADS)
Braun, M. A.
1991-02-01
The parton model for hA and AA interactions is developed for arbitrary dependence of parton amplitudes on energy. Conditions are studied under which the Glauber formula results for total cross sections. The fulfillment of the AGK rules is shown for all energies and registered particle momenta. Inclusive A'A cross sections in the forward hemisphere prove to be A' times larger than for NA collisions.
Strangeness asymmetry of the nucleon in the statistical parton model
NASA Astrophysics Data System (ADS)
Bourrely, Claude; Soffer, Jacques; Buccella, Franco
2007-04-01
We extend to the strange quarks and antiquarks, the statistical approach of parton distributions and we calculate the strange quark asymmetry s -sbar. We find that the asymmetry is small, positive in the low x region and negative in the high x region. In this framework, the polarized strange quarks and antiquarks distributions, which are obtained simultaneously, are found to be both negative for all x values.
Charm quark energy loss in infinite QCD matter using a parton cascade model
NASA Astrophysics Data System (ADS)
Younus, Mohammed; Coleman-Smith, Christopher E.; Bass, Steffen A.; Srivastava, Dinesh K.
2015-02-01
We utilize the parton cascade model to study the evolution of charm quarks propagating through a thermal brick of QCD matter. We determine the energy loss and the transport coefficient q ̂ for charm quarks. The calculations are done at a constant temperature of 350 MeV and the results are compared to analytical calculations of heavy-quark energy loss in order to validate the applicability of using a parton cascade model for the study of heavy-quark dynamics in hot and dense QCD matter.
Pion generalized parton distributions within a fully covariant constituent quark model
NASA Astrophysics Data System (ADS)
Fanelli, Cristiano; Pace, Emanuele; Romanelli, Giovanni; Salmè, Giovanni; Salmistraro, Marco
2016-05-01
We extend the investigation of the generalized parton distribution for a charged pion within a fully covariant constituent quark model, in two respects: (1) calculating the tensor distribution and (2) adding the treatment of the evolution, needed for achieving a meaningful comparison with both the experimental parton distribution and the lattice evaluation of the so-called generalized form factors. Distinct features of our phenomenological covariant quark model are: (1) a 4D Ansatz for the pion Bethe-Salpeter amplitude, to be used in the Mandelstam formula for matrix elements of the relevant current operators, and (2) only two parameters, namely a quark mass assumed to be m_q=~220 MeV and a free parameter fixed through the value of the pion decay constant. The possibility of increasing the dynamical content of our covariant constituent quark model is briefly discussed in the context of the Nakanishi integral representation of the Bethe-Salpeter amplitude.
Diphoton production in the ADD model to NLO + parton shower accuracy at the LHC
NASA Astrophysics Data System (ADS)
Frederix, R.; Mandal, Manoj K.; Mathews, Prakash; Ravindran, V.; Seth, Satyajit; Torrielli, P.; Zaro, M.
2012-12-01
In this paper, we present the next-to-leading order predictions for diphoton production in the ADD model, matched to the HERWIG parton shower using the MC@NLO formalism. A selection of the results is presented for d = 2-6 extra dimensions, using generic cuts as well as analysis cuts mimicking the search strategies as pursued by the ATLAS and CMS experiments.
Particle Identification in the Dynamical String-Parton Model of Relativistic Heavy-Ion Collisions
NASA Astrophysics Data System (ADS)
Malov, D. E.; Umar, A. S.; Ernst, D. J.; Dean, D. J.
The dynamical string-parton model for relativistic heavy-ion collisions is generalized to include particle identification of the final-state hadrons by phenomenologically quantizing the masses of the classical strings which result from string breaking. General features of the Nambu-Gotō strings are used to motivate a model that identifies a mass window near the physical mass of a meson, and does not allow the string to decay further if its mass falls within the window. Data from e+e- collisions in the region √ {s} =10 to 30 GeV are well reproduced by this model.
Low-P/sub T/ hadron production and a valon-parton recombination model
Amiri, F.
1981-01-01
A variant of the recombination model which we call the valon-parton model is applied simultaneously to a variety of meson inclusive reactions with proton, pion and kaon beams in the kinematic region of low transverse momentum and intermediate values of longitudinal momentum fractions. It is found that the valon distributions in hadrons show no evidence for SU(3) breaking. There are some indications of substantial gluon dissociation contributions which we interpreted through a maximally enhanced sea. For proton induced reactions the model predictions are in excellent agreement with the data; meson initiated reactions indicate additional contributions are coming from resonances which are produced recombinantly and then decay into the observed mesons.
Low-P/sub T/ hadron production and a valon-parton recombination model
Amiri, F.
1981-12-01
A variant of the recombination model which we call the valon-parton model is applied simultaneously to a variety of meson inclusive reactions with proton, pion and kaon beams in the kinematic region of low transverse momentum and intermediate values of longitudinal momentum fractions. It is found that the valon distributions in hadrons show no evidence for SU(3) breaking. There are some indications of substantial gluon dissociation contributions which we interpreted through a maximally enhanced sea. For proton induced reactions the model predictions are in excellent agreement with the data; meson initiated reactions indicate additional contributions are coming from resonances which are produced recombinantly and then decay into the observed mesons.
Energy loss in a partonic transport model including bremsstrahlung processes
Fochler, Oliver; Greiner, Carsten; Xu Zhe
2010-08-15
A detailed investigation of the energy loss of gluons that traverse a thermal gluonic medium simulated within the perturbative QCD-based transport model BAMPS (a Boltzmann approach to multiparton scatterings) is presented in the first part of this work. For simplicity the medium response is neglected in these calculations. The energy loss from purely elastic interactions is compared with the case where radiative processes are consistently included based on the matrix element by Gunion and Bertsch. From this comparison, gluon multiplication processes gg{yields}ggg are found to be the dominant source of energy loss within the approach employed here. The consequences for the quenching of gluons with high transverse momentum in fully dynamic simulations of Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC) energy of {radical}(s)=200A GeV are discussed in the second major part of this work. The results for central collisions as discussed in a previous publication are revisited, and first results on the nuclear modification factor R{sub AA} for noncentral Au+Au collisions are presented. They show a decreased quenching compared to central collisions while retaining the same shape. The investigation of the elliptic flow v{sub 2} is extended up to nonthermal transverse momenta of 10 GeV, exhibiting a maximum v{sub 2} at roughly 4 to 5 GeV and a subsequent decrease. Finally the sensitivity of the aforementioned results on the specific implementation of the effective modeling of the Landau-Pomeranchuk-Migdal (LPM) effect via a formation-time-based cutoff is explored.
NASA Astrophysics Data System (ADS)
Gavai, Rajiv V.; Venugopalan, Raju
1996-11-01
Using weak coupling methods McLerran and Venugopalan expressed the parton distributions in large nuclei as correlation functions of a two-dimensional Euclidean field theory. The theory has the dimensionful coupling g2μ, where μ2~A1/3 is the valence quark color charge squared per unit area. We use a lattice regularization to investigate these correlation functions both analytically and numerically for the simplified case of SU(2) gauge theory. In weak coupling (g2μL<<5), where L is the transverse size of the nucleus, the numerical results agree with the analytic lattice weak coupling results. For g2μL>>5, no solutions exist at O(a4) where a is the lattice spacing. This suggests an ill-defined infrared behavior for the two-dimensional theory. A recent proposal of Jalilian-Marian, Kovner, McLerran, and Weigert for an analytic solution of the classical problem is discussed briefly.
Multiplicity distributions up to √s = 540 GeV in the dual parton model
NASA Astrophysics Data System (ADS)
Capella, A.; Tran Thanh van, J.
1982-08-01
We compute the average charge multiplicities and dispersions in proton-proton and antiproton-proton interactions up to SPS collider energies in the framework of a multi-chain dual parton model. The corresponding data for deep inelastic lepton-proton and e+e- reactions are used as the sole input. The height of the central plateau is also computed. Laboratoire associé au Centre National de la Recherche Scientifique. Postal address: Bâtiment 211, Université Paris-Sud 91405 Orsay, France.
Transverse momentum dependent parton distributions in a light-cone quark model
NASA Astrophysics Data System (ADS)
Pasquini, B.; Cazzaniga, S.; Boffi, S.
2008-08-01
The leading twist transverse momentum dependent parton distributions (TMDs) are studied in a light-cone description of the nucleon where the Fock expansion is truncated to consider only valence quarks. General analytic expressions are derived in terms of the six amplitudes needed to describe the three-quark sector of the nucleon light-cone wave function. Numerical calculations for the T-even TMDs are presented in a light-cone constituent quark model, and the role of the so-called pretzelosity is investigated to produce a nonspherical shape of the nucleon.
Accardi, Alberto; Owens, Jeff F.
2013-07-01
Three new sets of next-to-leading order parton distribution functions (PDFs) are presented, determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep-inelastic scattering data at large x and low Q^2, and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF compared with previous fits. Applications to weak boson production at colliders are also discussed.
Thermalization of parton spectra in the colour-flux-tube model
NASA Astrophysics Data System (ADS)
Ryblewski, Radoslaw
2016-09-01
A detailed study of thermalization of the momentum spectra of partons produced via decays of colour flux tubes due to the Schwinger tunnelling mechanism is presented. The collisions between particles are included in the relaxation-time approximation specified by different values of the shear viscosity to entropy density ratio. At first we show that, to a good approximation, the transverse-momentum spectra of the produced partons are exponential, irrespective of the assumed value of the viscosity of the system and the freeze-out time. This thermal-like behaviour may be attributed to specific properties of the Schwinger tunnelling process. In the next step, in order to check the approach of the system towards genuine local equilibrium, we compare the local slope of the model transverse-momentum spectra with the local slope of the fully equilibrated reference spectra characterized by the effective temperature that reproduces the energy density of the system. We find that the viscosity corresponding to the anti-de Sitter/conformal field theory lower bound is necessary for thermalization of the system within about two fermis.
An upgraded issue of the parton and hadron cascade model, PACIAE 2.2
NASA Astrophysics Data System (ADS)
Zhou, Dai-Mei; Yan, Yu-Liang; Li, Xing-Long; Li, Xiao-Mei; Dong, Bao-Guo; Cai, Xu; Sa, Ben-Hao
2015-08-01
The parton and hadron cascade model PACIAE 2.1 (cf. Comput. Phys. Commun. 184 (2013) 1476) has been upgraded to the new issue of PACIAE 2.2. By this new issue the lepton-nucleon and lepton-nucleus (inclusive) deep inelastic scatterings can also be investigated. As an example, the PACIAE 2.2 model is enabled to calculate the specific charged hadron multiplicity in the e-+p and e-+D semi-inclusive deep-inelastic scattering at 27.6 GeV electron beam energy. The calculated results are well comparing with the corresponding HERMES data. Additionally, the effect of model parameters α and β in the Lund string fragmentation function on the multiplicity is studied.
Low-p/sub T/ hadron production and a valon-parton recombination model
Amiri, F.; Williams, P.K.
1981-11-01
We apply a variant of the recombination model which we call the ''valon-parton model'' simultaneously to a variety of meson inclusive reactions with proton, pion, and kaon beams in the kinematic region of low transverse momentum and intermediate values of longitudinal-momentum fractions. We find that the valon distributions in hadrons show no evidence for SU(3) breaking. There are some indications of substantial gluon-dissociation contributions which we interpret through a ''maximally enhanced sea.'' For proton-induced reactions the model predictions are in excellent agreement with data; meson-induced reactions indicate additional contributions are coming from resonances which are produced recombinantly and then decay into the observed mesons.
Parton distribution in pseudoscalar mesons with a light-front constituent quark model
NASA Astrophysics Data System (ADS)
de Melo, J. P. B. C.; Ahmed, Isthiaq; Tsushima, Kazuo
2016-05-01
We compute the distribution amplitudes of the pion and kaon in the light-front constituent quark model with the symmetric quark-bound state vertex function [1, 2, 3]. In the calculation we explicitly include the flavor-SU(3) symmetry breaking effect in terms of the constituent quark masses of the up (down) and strange quarks. To calculate the kaon parton distribution functions (PDFs), we use both the conditions in the light-cone wave function, i.e., when s ¯ quark is on-shell, and when u quark is on-shell, and make a comparison between them. The kaon PDFs calculated in the two different conditions clearly show asymmetric behaviour due to the flavor SU(3)-symmetry breaking implemented by the quark masses [4, 5].
Charge symmetry at the partonic level
Londergan, J. T.; Peng, J. C.; Thomas, A. W.
2010-07-01
This review article discusses the experimental and theoretical status of partonic charge symmetry. It is shown how the partonic content of various structure functions gets redefined when the assumption of charge symmetry is relaxed. We review various theoretical and phenomenological models for charge symmetry violation in parton distribution functions. We summarize the current experimental upper limits on charge symmetry violation in parton distributions. A series of experiments are presented, which might reveal partonic charge symmetry violation, or alternatively might lower the current upper limits on parton charge symmetry violation.
Access to generalized parton distributions at COMPASS
Nowak, Wolf-Dieter
2015-04-10
A brief experimentalist's introduction to Generalized Parton Distributions (GPDs) is given. Recent COMPASS results are shown on transverse target-spin asymmetries in hard exclusive ρ{sup 0} production and their interpretation in terms of a phenomenological model as indication for chiral-odd, transverse GPDs is discussed. For deeply virtual Compton scattering, it is briefly outlined how to access GPDs and projections are shown for future COMPASS measurements.
Are partons confined tachyons?
Noyes, H.P.
1996-03-01
The author notes that if hadrons are gravitationally stabilized ``black holes``, as discrete physics suggests, it is possible that partons, and in particular quarks, could be modeled as tachyons, i.e. particles having v{sup 2} > c{sup 2}, without conflict with the observational fact that neither quarks nor tachyons have appeared as ``free particles``. Some consequences of this model are explored.
NASA Astrophysics Data System (ADS)
Tuppan, Sam; Budnik, Garrett; Fox, Jordan
2014-09-01
The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. The Meson Cloud Model (MCM) has proven to be a natural explanation for strangeness in the proton because of meson-baryon splitting into kaon-hyperon pairs. Total strangeness is predicted by integrated splitting functions, which represent the probability that the proton will fluctuate into a given meson-baryon pair. However, the momentum distributions s (x) and s (x) in the proton are determined from convolution integrals that depend on the parton distribution functions (PDFs) used for the mesons and baryons in the MCM. Theoretical calculations of these momentum distributions use many different forms for these PDFs. In our investigation, we calculate PDFs for K, K*, Λ, and Σ from two-body wave functions in a Light Cone Model (LCM) of the hadrons. We use these PDFs in conjunction with the MCM to create a hybrid model and compare our results to other theoretical calculations, experimental data from NuTeV, HERMES, ATLAS, and global parton distribution analyses. This research has been supported in part by the
Transition from hadronic to partonic interactions for a composite spin-1/2 model of a nucleon
Tjon, J. A.; Wallace, S. J.
2000-12-01
A simple model of a composite nucleon is developed in which a fermion and a boson, representing quark and diquark constituents of the nucleon, form a bound state owing to a contact interaction. Photon and pion couplings to the quark provide vertex functions for the photon and pion interactions with the composite nucleon. By a suitable choice of cutoff parameters of the model, realistic electromagnetic form factors are obtained for the proton. When a pseudoscalar pion-quark coupling is used, the pion-nucleon coupling is predominantly pseudovector. A virtual photopion amplitude is considered in which there are two types of contributions: hadronic contributions where the photon and pion interactions have an intervening propagator of the nucleon or its excited states, and contactlike contributions where the photon and pion interactions occur within a single vertex. At large Q, the contactlike contributions are dominant. The model nucleon exhibits scaling behavior in deep-inelastic scattering and the normalization of the parton distribution provides a rough normalization of the contactlike contributions. Calculations for the virtual photopion amplitude are performed using kinematics appropriate to its occurrence as a meson-exchange current in electron-deuteron scattering. The results suggest that the contactlike terms can dominate the meson-exchange current for Q>1GeV/c. There is a direct connection of the contactlike terms to the off-forward parton distributions of the model nucleon.
NASA Astrophysics Data System (ADS)
Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; Baker, O. K.; Benmouna, N.; Bertoncini, C.; Blok, H. P.; Boeglin, W. U.; Bosted, P. E.; Breuer, H.; Christy, M. E.; Connell, S. H.; Cui, Y.; Dalton, M. M.; Danagoulian, S.; Day, D.; Dunne, J. A.; Dutta, D.; El Khayari, N.; Fenker, H. C.; Frolov, V. V.; Gan, L.; Gaskell, D.; Hafidi, K.; Hinton, W.; Holt, R. J.; Horn, T.; Huber, G. M.; Hungerford, E.; Jiang, X.; Jones, M.; Joo, K.; Kalantarians, N.; Kelly, J. J.; Keppel, C. E.; Kubarovsky, V.; Li, Y.; Liang, Y.; Mack, D.; Malace, S. P.; Markowitz, P.; McGrath, E.; McKee, P.; Meekins, D. G.; Mkrtchyan, A.; Moziak, B.; Niculescu, G.; Niculescu, I.; Opper, A. K.; Ostapenko, T.; Reimer, P. E.; Reinhold, J.; Roche, J.; Rock, S. E.; Schulte, E.; Segbefia, E.; Smith, C.; Smith, G. R.; Stoler, P.; Tang, L.; Ungaro, M.; Uzzle, A.; Vidakovic, S.; Villano, A.; Vulcan, W. F.; Wang, M.; Warren, G.; Wesselmann, F. R.; Wojtsekhowski, B.; Wood, S. A.; Xu, C.; Yuan, L.; Zheng, X.
2012-01-01
A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2>4 GeV2 (up to ≈7 GeV2) and range in four-momentum transfer squared 2
Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; et al
2012-01-01
A large set of cross sections for semi-inclusive electroproduction of charged pions (π±) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W2 > 4 GeV2 and range in four-momentum transfer squared 2 < Q2 < 4 (GeV/c)2, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, Pt2 < 0.2 (GeV/c)2. The invariant mass that goes undetected, Mx or W',more » is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and Pt2 dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π+ and π-) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.« less
NASA Astrophysics Data System (ADS)
Bellm, Johannes; Plätzer, Simon; Richardson, Peter; Siódmok, Andrzej; Webster, Stephen
2016-08-01
We report on the possibility of reweighting parton-shower Monte Carlo predictions for scale variations in the parton-shower algorithm. The method is based on a generalization of the Sudakov veto algorithm. We demonstrate the feasibility of this approach using example physical distributions. Implementations are available for both of the parton-shower modules in the Herwig 7 event generator.
Kovalenko, V. N.
2013-10-15
The soft part of proton-proton interaction is considered within a phenomenological model that involves the formation of color strings. Under the assumption that an elementary collision is associated with the interaction of two color dipoles, the total inelastic cross section and the multiplicity of charged particles are estimated in order to fix model parameters. Particular attention is given to modeling of exclusive parton distributions with allowance for the energy-conservation law and for fixing the center of mass, which are necessary for describing correlations. An algorithm that describes the fusion of strings in the transverse plane and which takes into account their finite rapidity width is developed. The influence of string-fusion effects on long-range correlations is found within this mechanism.
Extractions of polarized and unpolarized parton distribution functions
Jimenez-Delgado, Pedro
2014-01-01
An overview of our ongoing extractions of parton distribution functions of the nucleon is given. First JAM results on the determination of spin-dependent parton distribution functions from world data on polarized deep-inelastic scattering are presented first, and followed by a short report on the status of the JR unpolarized parton distributions. Different aspects of PDF analysis are briefly discussed, including effects of the nuclear structure of targets, target-mass corrections and higher twist contributions to the structure functions.
Nuclear Parton Distribution Functions
I. Schienbein, J.Y. Yu, C. Keppel, J.G. Morfin, F. Olness, J.F. Owens
2009-06-01
We study nuclear effects of charged current deep inelastic neutrino-iron scattering in the framework of a {chi}{sup 2} analysis of parton distribution functions (PDFs). We extract a set of iron PDFs which are used to compute x{sub Bj}-dependent and Q{sup 2}-dependent nuclear correction factors for iron structure functions which are required in global analyses of free nucleon PDFs. We compare our results with nuclear correction factors from neutrino-nucleus scattering models and correction factors for charged-lepton--iron scattering. We find that, except for very high x{sub Bj}, our correction factors differ in both shape and magnitude from the correction factors of the models and charged-lepton scattering.
Asaturyan, R.; Ent, R.; Mkrtchyan, H.; Navasardyan, T.; Tadevosyan, V.; Adams, G. S.; Ahmidouch, A.; Angelescu, T.; Arrington, J.; Asaturyan, A.; Baker, O. K.; Benmouna, N.; Bertoncini, C.; Blok, H. P.; Boeglin, W. U.; Bosted, P. E.; Breuer, H.; Christy, M. E.; Connell, S. H.; Cui, Y.; Dalton, M. M.; Danagoulian, S.; Day, D.; Dunne, J. A.; Dutta, D.; El Khayari, N.; Fenker, H. C.; Frolov, V. V.; Gan, L.; Gaskell, D.; Hafidi, K.; Hinton, W.; Holt, R. J.; Horn, T.; Huber, G. M.; Hungerford, E.; Jiang, X.; Jones, M.; Joo, K.; Kalantarians, N.; Kelly, J. J.; Keppel, C. E.; Kubarovsky, V.; Li, Y.; Liang, Y.; Mack, D.; Malace, S. P.; Markowitz, P.; McGrath, E.; McKee, P.; Meekins, D. G.; Mkrtchyan, A.; Moziak, B.; Niculescu, G.; Niculescu, I.; Opper, A. K.; Ostapenko, T.; Reimer, P. E.; Reinhold, J.; Roche, J.; Rock, S. E.; Schulte, E.; Segbefia, E.; Smith, C.; Smith, G. R.; Stoler, P.; Tang, L.; Ungaro, M.; Uzzle, A.; Vidakovic, S.; Villano, A.; Vulcan, W. F.; Wang, M.; Warren, G.; Wesselmann, F. R.; Wojtsekhowski, B.; Wood, S. A.; Xu, C.; Yuan, L.; Zheng, X.
2012-01-01
A large set of cross sections for semi-inclusive electroproduction of charged pions (π^{±}) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W^{2} > 4 GeV^{2} and range in four-momentum transfer squared 2 < Q^{2} < 4 (GeV/c)^{2}, and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, P_{t}^{2} < 0.2 (GeV/c)^{2}. The invariant mass that goes undetected, M_{x} or W', is in the nucleon resonance region, W' < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and P_{t}^{2} dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π^{+} and π^{-}) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.
NASA Astrophysics Data System (ADS)
Nam, Seung-il
2012-10-01
We investigate the parton-distribution functions (PDFs) for the positively charged pion and kaon at a low renormalization scale ˜1GeV. To this end, we employ the gauge-invariant effective chiral action from the nonlocal chiral-quark model, resulting in the vector currents being conserved. All the model parameters are determined phenomenologically with the normalization condition for PDF and the empirical values for the pseudoscalar meson weak-decay constants. We consider the momentum dependence of the effective quark mass properly within the model calculations. It turns out that the leading local contribution provides about 70% of the total strength for PDF, whereas the nonlocal one, which is newly taken into account in this work for the gauge invariance, does the rest. High-Q2 evolution to 27GeV2 is performed for the valance-quark distribution function, using the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation. The moments for the pion and kaon valance-quark distribution functions are also computed. The numerical results are compared with the empirical data and theoretical estimations, and show qualitatively agreement with them.
PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0
NASA Astrophysics Data System (ADS)
Sa, Ben-Hao; Zhou, Dai-Mei; Yan, Yu-Liang; Dong, Bao-Guo; Cai, Xu
2013-05-01
We have updated the parton and hadron cascade model PACIAE 2.0 (cf. Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Xiao-Mei Li, Sheng-Qin Feng, Bao-Guo Dong, Xu Cai, Comput. Phys. Comm. 183 (2012) 333.) to the new issue of PACIAE 2.1. The PACIAE model is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum pT is randomly sampled in the string fragmentation, the px and py components are originally put on the circle with radius pT randomly. Now it is put on the circumference of ellipse with half major and minor axes of pT(1+δp) and pT(1-δp), respectively, in order to better investigate the final state transverse momentum anisotropy. New version program summaryManuscript title: PACIAE 2.1: An updated issue of the parton and hadron cascade model PACIAE 2.0 Authors: Ben-Hao Sa, Dai-Mei Zhou, Yu-Liang Yan, Bao-Guo Dong, and Xu Cai Program title: PACIAE version 2.1 Journal reference: Catalogue identifier: Licensing provisions: none Programming language: FORTRAN 77 or GFORTRAN Computer: DELL Studio XPS and others with a FORTRAN 77 or GFORTRAN compiler Operating system: Linux or Windows with FORTRAN 77 or GFORTRAN compiler RAM: ≈ 1GB Number of processors used: Supplementary material: Keywords: relativistic nuclear collision; PYTHIA model; PACIAE model Classification: 11.1, 17.8 External routines/libraries: Subprograms used: Catalogue identifier of previous version: aeki_v1_0* Journal reference of previous version: Comput. Phys. Comm. 183(2012)333. Does the new version supersede the previous version?: Yes* Nature of problem: PACIAE is based on PYTHIA. In the PYTHIA model, once the hadron transverse momentum(pT)is randomly sampled in the string fragmentation, thepxandpycomponents are randomly placed on the circle with radius ofpT. This strongly cancels the final state transverse momentum asymmetry developed dynamically. Solution method: Thepxandpycomponent of hadron in the string fragmentation is now randomly placed on the circumference of an ellipse with
Unraveling hadron structure with generalized parton distributions
Andrei Belitsky; Anatoly Radyushkin
2004-10-01
The recently introduced generalized parton distributions have emerged as a universal tool to describe hadrons in terms of quark and gluonic degrees of freedom. They combine the features of form factors, parton densities and distribution amplitudes - the functions used for a long time in studies of hadronic structure. Generalized parton distributions are analogous to the phase-space Wigner quasi-probability function of non-relativistic quantum mechanics which encodes full information on a quantum-mechanical system. We give an extensive review of main achievements in the development of this formalism. We discuss physical interpretation and basic properties of generalized parton distributions, their modeling and QCD evolution in the leading and next-to-leading orders. We describe how these functions enter a wide class of exclusive reactions, such as electro- and photo-production of photons, lepton pairs, or mesons.
From many body wee partons dynamics to perfect fluid: a standard model for heavy ion collisions
Venugopalan, R.
2010-07-22
We discuss a standard model of heavy ion collisions that has emerged both from experimental results of the RHIC program and associated theoretical developments. We comment briefly on the impact of early results of the LHC program on this picture. We consider how this standard model of heavy ion collisions could be solidified or falsified in future experiments at RHIC, the LHC and a future Electro-Ion Collider.
Measurement of parton shower observables with OPAL
NASA Astrophysics Data System (ADS)
Fischer, N.; Gieseke, S.; Kluth, S.; Plätzer, S.; Skands, P.
2016-07-01
A study of QCD coherence is presented based on a sample of about 397,000 e+e- hadronic annihilation events collected at √s = 91 GeV with the OPAL detector at LEP. The study is based on four recently proposed observables that are sensitive to coherence effects in the perturbative regime. The measurement of these observables is presented, along with a comparison with the predictions of different parton shower models. The models include both conventional parton shower models and dipole antenna models. Different ordering variables are used to investigate their influence on the predictions.
SINGULARITIES OF GENERALIZED PARTON DISTRIBUTIONS
Anatoly Radyushkin
2012-12-01
We discuss recent developments in building models for generalized parton distributions (GPDs) that are based on the formalism of double distributions (DDs). A special attention is given to a careful analysis of the singularity structure of DDs. The DD formalism is applied to construction of a model GPDs with a singular Regge behavior. Within the developed DD-based approach, we discuss the structure of GPD sum rules. It is shown that separation of DDs into the so-called ``plus'' part and the D-term part may be treated as a renormalization procedure for the GPD sum rules. This approach is compared with an alternative prescription based on analytic regularization.
KOVCHEGOV,Y.V.
2000-04-25
The authors derive an equation determining the small-x evolution of the F{sub 2} structure function of a large nucleus which resumes a cascade of gluons in the leading logarithmic approximation using Mueller's color dipole model. In the traditional language it corresponds to resummation of the pomeron fan diagrams, originally conjectured in the GLR equation. The authors show that the solution of the equation describes the physics of structure functions at high partonic densities, thus allowing them to gain some understanding of the most interesting and challenging phenomena in small-x physics--saturation.
TOPICS IN THEORY OF GENERALIZED PARTON DISTRIBUTIONS
Radyushkin, Anatoly V.
2013-05-01
Several topics in the theory of generalized parton distributions (GPDs) are reviewed. First, we give a brief overview of the basics of the theory of generalized parton distributions and their relationship with simpler phenomenological functions, viz. form factors, parton densities and distribution amplitudes. Then, we discuss recent developments in building models for GPDs that are based on the formalism of double distributions (DDs). A special attention is given to a careful analysis of the singularity structure of DDs. The DD formalism is applied to construction of a model GPDs with a singular Regge behavior. Within the developed DD-based approach, we discuss the structure of GPD sum rules. It is shown that separation of DDs into the so-called ``plus'' part and the $D$-term part may be treated as a renormalization procedure for the GPD sum rules. This approach is compared with an alternative prescription based on analytic regularization.
Generalized parton distributions from deep virtual compton scattering at CLAS
Guidal, M.
2010-04-24
Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factors $H_{Im}$ and $\\tilde{H}_{Im}$ with uncertainties, in average, of the order of 30%.
Generalized parton distributions from deep virtual compton scattering at CLAS
Guidal, M.
2010-04-24
Here, we have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factorsmore » $$H_{Im}$$ and $$\\tilde{H}_{Im}$$ with uncertainties, in average, of the order of 30%.« less
Generalized parton distributions in AdS/QCD
Vega, Alfredo; Schmidt, Ivan; Gutsche, Thomas; Lyubovitskij, Valery E.
2011-02-01
The nucleon helicity-independent generalized parton distributions of quarks are calculated in the zero skewness case, in the framework of the anti-de Sitter/QCD model. The present approach is based on a matching procedure of sum rules relating the electromagnetic form factors to generalized parton distributions and anti-de Sitter modes.
Partonic Transverse Momentum Distributions
Rossi, Patrizia
2010-08-04
In recent years parton distributions have been generalized to account also for transverse degrees of freedom and new sets of more general distributions, Transverse Momentum Dependent (TMD) parton distributions and fragmentation functions were introduced. Different experiments worldwide (HERMES, COMPASS, CLAS, JLab-Hall A) have measurements of TMDs in semi-inclusive DIS processes as one of their main focuses of research. TMD studies are also an important part of the present and future Drell-Yan experiments at RICH and JPARC and GSI, respectively, Studies of TMDs are also one of the main driving forces of the Jefferson Lab (JLab) 12 GeV upgrade project. Progress in phenomenology and theory is flourishing as well. In this talk an overview of the latest developments in studies of TMDs will be given and newly released results, ongoing activities, as well as planned near term and future measurements will be discussed.
Dynamics of hot and dense nuclear and partonic matter
Bratkovskaya, E. L.; Cassing, W.; Linnyk, O.; Konchakovski, V. P.; Voronyuk, V.; Ozvenchuk, V.
2012-06-15
The dynamics of hot and dense nuclear matter is discussed from the microscopic transport point of view. The basic concepts of the Hadron-String-Dynamical transport model (HSD)-derived from Kadanoff-Baym equations in phase phase-are presented as well as 'highlights' of HSD results for different observables in heavy-ion collisions from 100 A MeV (SIS) to 21 A TeV(RHIC) energies. Furthermore, a novel extension of the HSD model for the description of the partonic phase-the Parton-Hadron-String-Dynamics (PHSD) approach-is introduced. PHSD includes a nontrivial partonic equation of state-in line with lattice QCD-as well as covariant transition rates from partonic to hadronic degrees of freedom. The sensitivity of hadronic observables to the partonic phase is demonstrated for relativistic heavy-ion collisions from the FAIR/NICA up to the RHIC energy regime.
Prospects For Measurements Of Generalized Parton Distributions At COMPASS
Neyret, Damien
2007-06-13
The concept of Generalized Parton Distributions extends classical parton distributions by giving a '3-dimensional' view of the nucleons, allowing to study correlations between the parton longitudinal momentum and its transverse position in the nucleon. Measurements of such generalized distributions can be done with the COMPASS experiment, in particular using Deeply Virtual Compton Scattering events. They require to modify the set-up of COMPASS by introducing a recoil proton detector, an additional electromagnetic calorimeter and a new liquid hydrogen target. These upgrades are presently under study, and the first data taking could take place in 2010.
Parton Distributions in the Impact Parameter Space
Matthias Burkardt
2009-08-01
Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when the target and/or quark is transversely polarized. In combination with the final state interactions, this transverse deformation provides a natural mechanism for naive-T odd transverse single-spin asymmetries in semi-inclusive DIS. The deformation can also be related to the transverse force acting on the active quark in polarized DIS at higher twist.
NASA Astrophysics Data System (ADS)
Guidal, M.
2010-09-01
We have analyzed the longitudinally polarized proton target asymmetry data of the Deep Virtual Compton process recently published by the HERMES Collaboration in terms of Generalized Parton Distributions. We have fitted these new data in a largely model-independent fashion and the procedure results in numerical constraints on the accent="true">H˜Im Compton Form Factor. We present its t- and ξ-dependencies. We also find improvement on the determination of two other Compton Form Factors, HRe and HIm.
Uphoff, Jan; Senzel, Florian; Fochler, Oliver; Wesp, Christian; Xu, Zhe; Greiner, Carsten
2015-03-20
The quark gluon plasma produced in ultrarelativistic heavy-ion collisions exhibits remarkable features. It behaves like a nearly perfect liquid with a small shear viscosity to entropy density ratio and leads to the quenching of highly energetic particles. We show that both effects can be understood for the first time within one common framework. Employing the parton cascade Boltzmann approach to multiparton scatterings, the microscopic interactions and the space-time evolution of the quark gluon plasma are calculated by solving the relativistic Boltzmann equation. Based on cross sections obtained from perturbative QCD with explicitly taking the running coupling into account, we calculate the nuclear modification factor and elliptic flow in ultrarelativistic heavy-ion collisions. With only one single parameter associated with coherence effects of medium-induced gluon radiation, the experimental data of both observables can be understood on a microscopic level. Furthermore, we show that perturbative QCD interactions with a running coupling lead to a sufficiently small shear viscosity to entropy density ratio of the quark gluon plasma, which provides a microscopic explanation for the observations stated by hydrodynamic calculations. PMID:25839262
NASA Astrophysics Data System (ADS)
Shi, Shusu
2009-10-01
The measurement of event anisotropy, often called v2, provides a powerful tool for studying the properties of hot and dense medium created in high-energy nuclear collisions. The important discoveries of partonic collectivity and the brand-new process for hadronization - quark coalescence were obtained through a systematic analysis of the v2 for 200 GeV Au+Au collisions at RHIC [1]. However, early dynamic information might be masked by later hadronic rescatterings. Multistrange hadrons (φ, ξ and φ) with their large mass and presumably small hadronic cross sections should be less sensitive to hadronic rescattering in the later stage of the collisions and therefore a good probe of the early stage of the collision. We will present the measurement of v2 of π, p, KS^0, λ, ξ, φ and φ in heavy ion collisions. In minimum-bias Au+Au collisions at √sNN = 200 GeV, a significant amount of elliptic flow, almost identical to other mesons and baryons, is observed for φ and φ. Experimental observations of pT dependence of v2 of identified particles at RHIC support partonic collectivity. [4pt] [1] B. I. Abelev et al., (STAR Collaboration), Phys. Rev. C 77, 054901 (2008).
The statistical parton distributions: status and prospects
NASA Astrophysics Data System (ADS)
Bourrely, C.; Soffer, J.; Buccella, F.
2005-06-01
New experimental results on polarized structure functions, cross sections for e^{±}p neutral and charge current reactions and ν (bar{ν}) charge current on isoscalar targets are compared with predictions using the statistical parton distributions, which were previously determined. New data on cross sections for Drell-Yan processes, single-jet data in pbar{p} collisions and inclusive π^0 production data in pp collisions are also compared with predictions from this theoretical approach. The good agreement which we find with all these tests against experiment strengthens our opinion on the relevance of the role of quantum statistics for parton distributions. We will also discuss the prospects of this physical framework.
Tetraquark production in double parton scattering
NASA Astrophysics Data System (ADS)
Carvalho, F.; Cazaroto, E. R.; Gonçalves, V. P.; Navarra, F. S.
2016-02-01
We develop a model to study tetraquark production in hadronic collisions. We focus on double parton scattering and formulate a version of the color evaporation model for the production of the X (3872 ) and of the T4 c tetraquark, a state composed by the c c ¯c c ¯ quarks. We find that the production cross section grows rapidly with the collision energy √{s } and make predictions for the forthcoming higher energy data of the LHC.
New parton distributions from large-x and low-Q^{2} data
Alberto Accardi; Christy, M. Eric; Keppel, Cynthia E.; Melnitchouk, Wally; Monaghan, Peter A.; Morfin, Jorge G.; Owens, Joseph F.
2010-02-11
We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x. Effects of target mass corrections (TMCs), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. Furthermore, the behavior of the d quark as x → 1 is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models the d-quark distribution at large x is found to be softer than in previous fits performed with more restrictive cuts.
New parton distributions from large-x and low-Q^2 data
Alberto Accardi; Christy, M. Eric; Keppel, Cynthia E.; Melnitchouk, Wally; Monaghan, Peter A.; Morfin, Jorge G.; Owens, Joseph F.
2010-02-01
We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x. Effects of target mass corrections (TMCs), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. The behavior of the d quark as x -> 1 is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models themore » d-quark distribution at large x is found to be softer than in previous fits performed with more restrictive cuts.« less
New parton distributions from large-x and low-Q^2 data
Alberto Accardi, M. Eric Christy, Cynthia E. Keppel, Peter Monaghan, Wolodymyr Melnitchouk, Jorge G. Morfin, Joseph F. Owens
2010-02-01
We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x. Effects of target mass corrections (TMCs), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. The behavior of the d quark as x -> 1 is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models the d-quark distribution at large x is found to be softer than in previous fits performed with more restrictive cuts.
NASA Astrophysics Data System (ADS)
Knospe, A. G.; Markert, C.; Werner, K.; Steinheimer, J.; Bleicher, M.
2016-01-01
We study the production of hadronic resonances and their interaction in the partonic and hadronic medium using the EPOS3 model, which employs the UrQMD model for the description of the hadronic phase. We investigate the centrality dependence of the yields and momentum distributions for various resonances [ρ (770) 0 , K*(892) 0 , ϕ (1020 ) , Δ (1232) ++ , Σ (1385) ± , Λ (1520 ) , Ξ (1530) 0 and their antiparticles] in Pb-Pb collisions at √{sN N}= 2.76 TeV. The predictions for K*(892) 0 and ϕ (1020 ) will be compared with the experimental data from the ALICE collaboration. The observed signal suppression of the K*(892) 0 with increasing centrality will be discussed with respect to the resonance interaction in the hadronic medium. The mean transverse momentum and other particle ratios such as ϕ (1020 )/p and (Ω +Ω ¯) /ϕ (1020 ) will be discussed with respect to additional contributions from the hadronic medium interactions.
Generalized Parton Distributions and their Singularities
Anatoly Radyushkin
2011-04-01
A new approach to building models of generalized parton distributions (GPDs) is discussed that is based on the factorized DD (double distribution) Ansatz within the single-DD formalism. The latter was not used before, because reconstructing GPDs from the forward limit one should start in this case with a very singular function $f(\\beta)/\\beta$ rather than with the usual parton density $f(\\beta)$. This results in a non-integrable singularity at $\\beta=0$ exaggerated by the fact that $f(\\beta)$'s, on their own, have a singular $\\beta^{-a}$ Regge behavior for small $\\beta$. It is shown that the singularity is regulated within the GPD model of Szczepaniak et al., in which the Regge behavior is implanted through a subtracted dispersion relation for the hadron-parton scattering amplitude. It is demonstrated that using proper softening of the quark-hadron vertices in the regions of large parton virtualities results in model GPDs $H(x,\\xi)$ that are finite and continuous at the "border point'' $x=\\xi$. Using a simple input forward distribution, we illustrate the implementation of the new approach for explicit construction of model GPDs. As a further development, a more general method of regulating the $\\beta=0$ singularities is proposed that is based on the separation of the initial single DD $f(\\beta, \\alpha)$ into the "plus'' part $[f(\\beta,\\alpha)]_{+}$ and the $D$-term. It is demonstrated that the "DD+D'' separation method allows to (re)derive GPD sum rules that relate the difference between the forward distribution $f(x)=H(x,0)$ and the border function $H(x,x)$ with the $D$-term function $D(\\alpha)$.
Generalized parton distributions and their singularities
Radyushkin, A. V.
2011-04-01
A new approach to building models of generalized parton distributions (GPDs) is discussed that is based on the factorized DD (double distribution) ansatz within the single-DD formalism. The latter was not used before, because reconstructing GPDs from the forward limit one should start in this case with a very singular function f({beta})/{beta} rather than with the usual parton density f({beta}). This results in a nonintegrable singularity at {beta}=0 exaggerated by the fact that f({beta})'s, on their own, have a singular {beta}{sup -a} Regge behavior for small {beta}. It is shown that the singularity is regulated within the GPD model of Szczepaniak et al., in which the Regge behavior is implanted through a subtracted dispersion relation for the hadron-parton scattering amplitude. It is demonstrated that using proper softening of the quark-hadron vertices in the regions of large parton virtualities results in model GPDs H(x,{xi}) that are finite and continuous at the 'border point' x={xi}. Using a simple input forward distribution, we illustrate implementation of the new approach for explicit construction of model GPDs. As a further development, a more general method of regulating the {beta}=0 singularities is proposed that is based on the separation of the initial single DD f({beta},{alpha}) into the 'plus' part [f({beta},{alpha})]{sub +} and the D term. It is demonstrated that the ''DD+D'' separation method allows one to (re)derive GPD sum rules that relate the difference between the forward distribution f(x)=H(x,0) and the border function H(x,x) with the D-term function D({alpha}).
Parton Saturation and the Color Glass Condensate
NASA Astrophysics Data System (ADS)
Kovchegov, Yuri V.
2007-03-01
We review recent developments in the field of parton saturation and the Color Glass Condensate. We discuss the classical gluon fields of McLerran-Venugopalan model. We explain how small- x non-linear quantum evolution corrections can be included into the total cross section for deep inelastic scattering. We proceed by reviewing saturation physics predictions for the particle production in p( d) A collisions and conclude by demonstrating how such predictions were confirmed by the RHIC experiments.
Strongly interacting parton matter equilibration
Ozvenchuk, V.; Linnyk, O.; Bratkovskaya, E.; Gorenstein, M.; Cassing, W.
2012-07-15
We study the kinetic and chemical equilibration in 'infinite' parton matter within the Parton-Hadron-String Dynamics transport approach. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different energy densities. Particle abundances, kinetic energy distributions, and the detailed balance of the off-shell quarks and gluons in the strongly-interacting quarkgluon plasma are addressed and discussed.
New parton distributions from large-x and low-Q2 data
Alberto Accardi; Christy, M. Eric; Keppel, Cynthia E.; Melnitchouk, Wally; Monaghan, Peter A.; Morfin, Jorge G.; Owens, Joseph F.
2010-02-11
We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on W and Q are relaxed, thereby including more data at high values of x. Effects of target mass corrections (TMCs), higher twist contributions, and nuclear corrections for deuterium data are significant in the large-x region. The leading twist parton distributions are found to be stable to TMC model variations as long as higher twist contributions are also included. Furthermore, the behavior of the d quark as x → 1 is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing modelsmore » the d-quark distribution at large x is found to be softer than in previous fits performed with more restrictive cuts.« less
Chiral-odd generalized parton distributions in transverse and longitudinal impact parameter spaces
Chakrabarti, D.; Manohar, R.; Mukherjee, A.
2009-02-01
We investigate the chiral-odd generalized parton distributions for nonzero skewness {zeta} in transverse and longitudinal position spaces by taking Fourier transform with respect to the transverse and longitudinal momentum transfer, respectively. We present overlap formulas for the chiral-odd generalized parton distributions in terms of light-front wave functions (LFWFs) of the proton both in the Efremov-Radyushkin-Brodsky-Lepage and Dokshitzer-Gribov-Lipatov-Altarelli-Parisi regions. We calculate them in a field theory inspired model of a relativistic spin-1/2 composite state with the correct correlation between the different LFWFs in Fock space, namely, that of the quantum fluctuations of an electron in a generalized form of QED. We show the spin-orbit correlation effect of the two-particle LFWF as well as the correlation between the constituent spin and the transverse spin of the target.
Chiral-odd generalized parton distributions in transverse and longitudinal impact parameter spaces
NASA Astrophysics Data System (ADS)
Chakrabarti, D.; Manohar, R.; Mukherjee, A.
2009-02-01
We investigate the chiral-odd generalized parton distributions for nonzero skewness ζ in transverse and longitudinal position spaces by taking Fourier transform with respect to the transverse and longitudinal momentum transfer, respectively. We present overlap formulas for the chiral-odd generalized parton distributions in terms of light-front wave functions (LFWFs) of the proton both in the Efremov-Radyushkin-Brodsky-Lepage and Dokshitzer-Gribov-Lipatov-Altarelli-Parisi regions. We calculate them in a field theory inspired model of a relativistic spin-1/2 composite state with the correct correlation between the different LFWFs in Fock space, namely, that of the quantum fluctuations of an electron in a generalized form of QED. We show the spin-orbit correlation effect of the two-particle LFWF as well as the correlation between the constituent spin and the transverse spin of the target.
Jet fragmentation via recombination of parton showers
NASA Astrophysics Data System (ADS)
Han, Kyong Chol; Fries, Rainer J.; Ko, Che Ming
2016-04-01
We propose to model hadronization of parton showers in QCD jets through a hybrid approach involving quark recombination and string fragmentation. This is achieved by allowing gluons at the end of the perturbative shower evolution to undergo a nonperturbative splitting into quark and antiquark pairs, then applying a Monte Carlo version of instantaneous quark recombination, and finally subjecting remnant quarks (those which have not found a recombination partner) to Lund string fragmentation. When applied to parton showers from the pythia Monte Carlo event generator, the final hadron spectra from our calculation compare quite well to pythia jets that have been hadronized with the default Lund string fragmentation. Our new approach opens up the possibility to generalize hadronization to jets embedded in a quark gluon plasma.
Global parton distributions with nuclear and finite-Q^2 corrections
Owens, J. F.; Accardi, Alberto; Melnitchouk, Wally
2013-05-01
We present three new sets of parton distribution functions (PDFs) determined by global fits to a wide variety of data for hard scattering processes. The analysis includes target mass and higher twist corrections needed for the description of deep inelastic scattering data at large x and low Q^2, and nuclear corrections for deuterium targets. The PDF sets correspond to three different models for the nuclear effects, and provide a more realistic uncertainty range for the d quark PDF, in particular, compared with previous fits. We describe the PDF error sets for each choice of the nuclear corrections, and provide a user interface for utilizing the distributions.
Fermi-Dirac distributions for quark partons
NASA Astrophysics Data System (ADS)
Bourrely, C.; Buccella, F.; Miele, G.; Migliore, G.; Soffer, J.; Tibullo, V.
1994-09-01
We propose to use Fermi-Dirac distributions for quark and antiquark partons. It allows a fair description of the x-dependence of the very recent NMC data on the proton and neutron structure functions F {2/ p } (x) and F {2/ n } (x) at Q 2=4 GeV2, as well as the CCFR antiquark distributionxbar q(x). We show that one can also use a corresponding Bose-Einstein expression to describe consistently the gluon distribution. The Pauli exclusion principle, which has been identified to explain the flavor asymmetry of the light-quark sea of the proton, is advocated to guide us for making a simple construction of the polarized parton distributions. We predict the spin dependent structure functions g {1/ p } (x) and g {1/ n } (x) in good agreement with EMC and SLAC data. The quark distributions involve some parameters whose values support well the hypothesis that the violation of the quark parton model sum rules is a consequence of the Pauli principle.
Tests of models for parton fragmentation in e e annihilation. [29 GeV center-of-mass energy
Gary, J.W.
1985-11-01
We examine the distribution of particles in the three jet events of e e annihilation. The data was collected with the PEP-4/Time Projection Chamber detector at 29 GeV center-of-mass energy at PEP. The experimental distributions are compared to the predictions of several fragmentation models which describe the transition of quarks and gluons into hadrons. In particular, our study emphasizes the three fragmentation models which are currently in widest use: the Lund string model, the Webber cluster model and the independent fragmentation model. These three models each possess different Lorentz frame structures for the distribution of hadron sources relative to the overall event c.m. in three jet events. The Lund string and independent fragmentation models are tuned to describe global event properties of our multihadronic annihilation event sample. This tuned Lund string model provides a good description of the distribution of particles between jet axes in three jet events, while the independent fragmentation model does not. We verify that the failure of the independent fragmentation model is not a consequence of parameter tuning or of model variant. The Webber cluster model, which is untuned, does not describe the absolute particle densities between jets but correctly predicts the ratios of those densities, which are less sensitive to the tuning. These results provide evidence that the sources of hadrons are boosted with respect to the overall center-of-mass in three jet events, with components of motion normal to the jet axes. The distribution of particles close to jet axes provides additional support for this conclusion. 94 refs.
Partonic substructure of nucleons and nuclei with dimuon production
Peng, J. C.
2010-07-27
Dimuon production has been studied in a series of fixed-target experiments at Fermilab during the last two decades. Highlights from these experiments, together with recent results from the Fermilab E866 experiment, are presented. Future prospects for studying the parton distributions in the nucleons and nuclei using dimuon production are also discussed.
Medium Effects in Parton Distributions
William Detmold, Huey-Wen Lin
2011-12-01
A defining experiment of high-energy physics in the 1980s was that of the EMC collaboration where it was first observed that parton distributions in nuclei are non-trivially related to those in the proton. This result implies that the presence of the nuclear medium plays an important role and an understanding of this from QCD has been an important goal ever since Here we investigate analogous, but technically simpler, effects in QCD and examine how the lowest moment of the pion parton distribution is modified by the presence of a Bose-condensed gas of pions or kaons.
Parton distributions from lattice QCD: an update
Detmold, W; Melnitchouk, W; Thomas, A W
2004-04-01
We review the extraction of parton distributions from their moments calculated in lattice QCD, focusing in particular on their extrapolation to the physical region. As examples, we consider both the unpolarized and polarized isovector parton distributions of the nucleon.
Experimental studies of Generalized Parton Distributions
NASA Astrophysics Data System (ADS)
Niccolai, Silvia
2015-12-01
Generalized Parton Distributions (GPDs) are nowadays the object of an intense effort of research, in the perspective of understanding nucleon structure. They describe the correlations between the longitudinal momentum and the transverse spatial position of the partons inside the nucleon and they can give access to the contribution of the orbital momentum of the quarks to the nucleon spin. Deeply Virtual Compton scattering (DVCS), the electroproduction on the nucleon, at the quark level, of a real photon, is the process more directly interpretable in terms of GPDs of the nucleon. Depending on the target nucleon (proton or neutron) and on the DVCS observable extracted (cross-sections, target- or beam-spin asymmetries, etc.), different sensitivity to the various GPDs for each quark flavor can be exploited. This article is focused on recent promising results, obtained at Jefferson Lab, on cross-sections and asymmetries for DVCS, and their link to GPDs. These data open the way to a “tomographic” representation of the structure of the nucleon, allowing the extraction of transverse-space densities of the quarks at fixed longitudinal momentum. The extensive experimental program to measure GPDs at Jefferson Lab with the 12 GeV-upgraded electron accelerator and the complementary detectors that will be housed in three experimental Halls (A, B and C), will also be presented.
First moments of nucleon generalized parton distributions
Wang, P.; Thomas, A. W.
2010-06-01
We extrapolate the first moments of the generalized parton distributions using heavy baryon chiral perturbation theory. The calculation is based on the one loop level with the finite range regularization. The description of the lattice data is satisfactory, and the extrapolated moments at physical pion mass are consistent with the results obtained with dimensional regularization, although the extrapolation in the momentum transfer to t=0 does show sensitivity to form factor effects, which lie outside the realm of chiral perturbation theory. We discuss the significance of the results in the light of modern experiments as well as QCD inspired models.
Electroweak boson production in double parton scattering
NASA Astrophysics Data System (ADS)
Golec-Biernat, Krzysztof; Lewandowska, Emilia
2014-11-01
We study the W+W- and Z0Z0 electroweak boson production in double parton scattering using QCD evolution equations for double parton distributions. In particular, we analyze the impact of splitting terms in the evolution equations on the double parton scattering cross sections. Unlike the standard terms, the splitting terms are not suppressed for large values of the relative momentum of two partons in the double parton scattering. Thus, they play an important role which we discuss in detail for the single splitting contribution to the cross sections under the study.
Generalized parton distributions and Deeply Virtual Compton Scattering on proton at CLAS
R. De Masi
2007-12-01
Two measurements of target and beam spin asymmetries for the reaction ep→epγ were performed with CLAS at Jefferson Laboratory. Polarized 5.7 GeV electrons were impinging on a longitudinally polarized ammonia and liquid hydrogen target respectively. These measurements are sensitive to Generalized Parton Distributions. Sizable sin phi azimuthal angular dependences were observed in both experiments, indicating the dominance of leading twist terms and the possibility of extracting combinations of Generalized Parton Distributions on the nucleon.
Applying target shadow models for SAR ATR
NASA Astrophysics Data System (ADS)
Papson, Scott; Narayanan, Ram M.
2007-04-01
Recent work has suggested that target shadows in synthetic aperture radar (SAR) images can be used effectively to aid in target classification. The method outlined in this paper has four steps - segmentation, representation, modeling, and selection. Segmentation is the process by which a smooth, background-free representation of the target's shadow is extracted from an image chip. A chain code technique is then used to represent the shadow boundary. Hidden Markov modeling is applied to sets of chain codes for multiple targets to create a suitable bank of target representations. Finally, an ensemble framework is proposed for classification. The proposed model selection process searches for an optimal ensemble of models based on various target model configurations. A five target subset of the MSTAR database is used for testing. Since the shadow is a back-projection of the target profile, some aspect angles will contain more discriminatory information then others. Therefore, performance is investigated as a function of aspect angle. Additionally, the case of multiple target looks is considered. The capability of the shadow-only classifier to enhance more traditional classification techniques is examined.
Generalized parton correlation functions for a spin-1/2 hadron
Stephan Meissner, Andreas Metz, Marc Schlegel
2009-08-01
The fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects, in particular, can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. We find that none of these relations can be promoted to a model-independent status. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist. The present paper is a natural extension of our previous corresponding analysis for spin-0 hadrons.
Structure functions and parton distributions
Martin, A.D.; Stirling, W.J.; Roberts, R.G.
1995-07-01
The MRS parton distribution analysis is described. The latest sets are shown to give an excellent description of a wide range of deep-inelastic and other hard scattering data. Two important theoretical issues-the behavior of the distributions at small x and the flavor structure of the quark sea-are discussed in detail. A comparison with the new structure function data from HERA is made, and the outlook for the future is discussed.
Generalized parton distributions in nuclei
Vadim Guzey
2009-12-01
Generalized parton distributions (GPDs) of nuclei describe the distribution of quarks and gluons in nuclei probed in hard exclusive reactions, such as e.g. deeply virtual Compton scattering (DVCS). Nuclear GPDs and nuclear DVCS allow us to study new aspects of many traditional nuclear effects (nuclear shadowing, EMC effect, medium modifications of the bound nucleons) as well as to access novel nuclear effects. In my talk, I review recent theoretical progress in the area of nuclear GPDs.
Deeply Virtual Exclusive Processes and Generalized Parton Distributions
,
2011-06-01
The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.
A Review of Target Mass Corrections
I. Schienbein; V. Radescu; G. Zeller; M. E. Christy; C. E. Keppel; K. S. McFarland; W. Melnitchouk; F. I. Olness; M. H. Reno; F. Steffens; J.-Y. Yu
2007-09-06
With recent advances in the precision of inclusive lepton-nuclear scattering experiments, it has become apparent that comparable improvements are needed in the accuracy of the theoretical analysis tools. In particular, when extracting parton distribution functions in the large-x region, it is crucial to correct the data for effects associated with the nonzero mass of the target. We present here a comprehensive review of these target mass corrections (TMC) to structure functions data, summarizing the relevant formulas for TMCs in electromagnetic and weak processes. We include a full analysis of both hadronic and partonic masses, and trace how these effects appear in the operator product expansion and the factorized parton model formalism, as well as their limitations when applied to data in the x -> 1 limit. We evaluate the numerical effects of TMCs on various structure functions, and compare fits to data with and without these corrections.
Parton-parton elastic scattering and rapidity gaps at SSC and LHC energies
Duca, V.D.
1993-08-01
The theory of the perturbative pomeron, due to Lipatov and collaborators, is used to compute the probability of observing parton-parton elastic scattering and rapidity gaps between jets in hadron collisions at SSC and LHC energies.
Parton-parton elastic scattering and rapidity gaps at Tevatron energies
Del Duca, V.; Tang, Wai-Keung
1993-08-01
The theory of the perturbative pomeron, due to Lipatov and collaborators, is used to compute the probability of observing parton-parton elastic scattering and rapidity gaps between jets in hadron collisions at Tevatron energies.
Partonic orbital angular momentum
NASA Astrophysics Data System (ADS)
Arash, Firooz; Taghavi-Shahri, Fatemeh; Shahveh, Abolfazl
2013-04-01
Ji's decomposition of nucleon spin is used and the orbital angular momentum of quarks and gluon are calculated. We have utilized the so called valon model description of the nucleon in the next to leading order. It is found that the average orbital angular momentum of quarks is positive, but small, whereas that of gluon is negative and large. Individual quark flavor contributions are also calculated. Some regularities on the total angular momentum of the quarks and gluon are observed.
Parton interpretation of the nucleon spin-dependent structure functions
Mankiewicz, L. ); Ryzak, Z. )
1991-02-01
We discuss the interpretation of the nucleon's polarized structure function {ital g}{sub 2}({ital x}). If the target state is represented by its Fock decomposition on the light cone, the operator-product expansion allows us to demonstrate that moments of {ital g}{sub 2}({ital x}) are related to overlap integrals between wave functions of opposite longitudinal polarizations. In the light-cone formalism such wave functions are related by the kinematical operator {ital scrY}, or light-cone parity. As a consequence, it can be shown that moments of {ital g}{sub 2} give information about the same parton wave function, or probability amplitude to find a certain parton configuration in the target which defines {ital g}{sub 1}({ital x}) or {ital F}{sub 2}({ital x}). Specific formulas are given, and possible applications to the phenomenology of the nucleon structure in QCD are discussed.
The Transverse Momentum Dependent Statistical Parton Distributions Revisited
NASA Astrophysics Data System (ADS)
Bourrely, Claude; Buccella, Franco; Soffer, Jacques
2013-04-01
The extension of the statistical parton distributions to include their transverse momentum dependence (TMD) is revisited by considering that the proton target has a finite longitudinal momentum. The TMD will be generated by means of a transverse energy sum rule. The new results are mainly relevant for electron-proton inelastic collisions in the low Q2 region. We take into account the effects of the Melosh-Wigner rotation for the helicity distributions.
Nuclear modifications of Parton Distribution Functions
NASA Astrophysics Data System (ADS)
Adeluyi, Adeola Adeleke
-called shadowing region. We also investigate the effects of nuclear modifications on observed quantities in ultrarelativistic nucleus-nucleus collisions. Specifically, we consider deuteron-gold collisions and observables which are directly impacted by modifications, such as pseudorapidity asymmetry and nuclear modification factors. A good description of the shadowing region is afforded by Gribov Theory. Gribov related the shadowing correction to the differential diffractive hadron-nucleon cross section. We generalize Gribov theory to include both the real part of the diffractive scattering amplitude and higher order multiple scattering necessary for heavy nuclei. The diffractive dissociation inputs are taken from experiments. We calculate observables in deuteron-gold collisions. Utilizing the factorization theorem, we use the existing parameterizations of nuclear PDFs and fragmentation functions in a pQCD-improved parton model to calculate nuclear modification factors and pseudorapidity asymmetries. The nuclear modification factor is essentially the ratio of the deuteron-gold cross section to that of the proton-proton cross section scaled by the number of binary collisions. The pseudorapidity asymmetry is the ratio of the cross section in the negative rapidity region relative to that in the equivalent positive rapidity region. Both quantities are sensitive to the effects of nuclear modifications on PDFs. Results are compared to experimental data from the BRAHMS and STAR collaborations.
Statistical Modeling of Single Target Cell Encapsulation
Moon, SangJun; Ceyhan, Elvan; Gurkan, Umut Atakan; Demirci, Utkan
2011-01-01
High throughput drop-on-demand systems for separation and encapsulation of individual target cells from heterogeneous mixtures of multiple cell types is an emerging method in biotechnology that has broad applications in tissue engineering and regenerative medicine, genomics, and cryobiology. However, cell encapsulation in droplets is a random process that is hard to control. Statistical models can provide an understanding of the underlying processes and estimation of the relevant parameters, and enable reliable and repeatable control over the encapsulation of cells in droplets during the isolation process with high confidence level. We have modeled and experimentally verified a microdroplet-based cell encapsulation process for various combinations of cell loading and target cell concentrations. Here, we explain theoretically and validate experimentally a model to isolate and pattern single target cells from heterogeneous mixtures without using complex peripheral systems. PMID:21814548
Modeling target erosion during reactive sputtering
NASA Astrophysics Data System (ADS)
Strijckmans, K.; Depla, D.
2015-03-01
The influence of the reactive sputter conditions on the racetrack and the sputter profile for an Al/O2 DC reactive sputter system is studied by modeling. The role of redeposition, i.e. the deposition of sputtered material back on the target, is therefore taken into account. The used model RSD2013 is capable of simulating the effect of redeposition on the target condition in a spatial resolved way. Comparison between including and excluding redeposition in the RSD2013 model shows that the in-depth oxidation profile of the target differs. Modeling shows that it is important to distinguish between the formed racetrack, i.e. the erosion depth profile, and the sputter profile. The latter defines the distribution of the sputtered atoms in the vacuum chamber. As the target condition defines the sputter yield, it does determine the racetrack and the sputter profile of the planar circular target. Both the shape of the racetrack and the sputter profile change as function of the redeposition fraction as well as function of the oxygen flow change. Clear asymmetries and narrowing are observed for the racetrack shape. Similar effects are noticed for the sputter profile but to a different extent. Based on this study, the often heard misconception that the racetrack shape defines the distribution of the sputtered atoms during reactive sputtering is proven to be wrong.
The parton distribution function library
Plothow-Besch, H.
1995-07-01
This article describes an integrated package of Parton Density Functions called PDFLIB which has been added to the CERN Program Library Pool W999 and is labelled as W5051. In this package all the different sets of parton density functions of the Nucleon, Pion and the Photon which are available today have been put together. All these sets have been combined in a consistent way such that they all have similar calling sequences and no external data files have to be read in anymore. A default set has been prepared, although those preferring their own set or wanting to test a new one may do so within the package. The package also offers a program to calculate the strong coupling constant {alpha}, to first or second order. The correct {Lambda}{sub QCD} associated to the selected set of structure functions and the number of allowed flavours with respect to the given Q{sup 2} is automatically used in the calculation. The selection of sets, the program parameters as well as the possibilities to modify the defaults and to control errors occurred during execution are described.
Jet correlations from unintegrated parton distributions
Hautmann, F.; Jung, H.
2008-10-13
Transverse-momentum dependent parton distributions can be introduced gauge-invariantly in QCD from high-energy factorization. We discuss Monte Carlo applications of these distributions to parton showers and jet physics, with a view to the implications for the Monte Carlo description of complex hadronic final states with multiple hard scales at the LHC.
Introduction to Parton-Shower Event Generators
NASA Astrophysics Data System (ADS)
Höche, Stefan
This lecture discusses the physics implemented by Monte Carlo event generators for hadron colliders. It details the construction of parton showers and the matching of parton showers to fixed-order calculations at higher orders in perturbative QCD. It also discusses approaches to merge calculations for a varying number of jets, the interface to the underlying event and hadronization.
Illuminating the 1/x Moment of Parton Distribution Functions
Brodsky, Stanley J.; Llanes-Estrada, Felipe J.; Szczepaniak, Adam P.; /Indiana U.
2007-10-15
The Weisberger relation, an exact statement of the parton model, elegantly relates a high-energy physics observable, the 1/x moment of parton distribution functions, to a nonperturbative low-energy observable: the dependence of the nucleon mass on the value of the quark mass or its corresponding quark condensate. We show that contemporary fits to nucleon structure functions fail to determine this 1/x moment; however, deeply virtual Compton scattering can be described in terms of a novel F1/x(t) form factor which illuminates this physics. An analysis of exclusive photon-induced processes in terms of the parton-nucleon scattering amplitude with Regge behavior reveals a failure of the high Q2 factorization of exclusive processes at low t in terms of the Generalized Parton-Distribution Functions which has been widely believed to hold in the past. We emphasize the need for more data for the DVCS process at large t in future or upgraded facilities.
Neutrino Production of Mesons in the Generalized Parton Picture
NASA Astrophysics Data System (ADS)
McAskill, Tracy
The handbag model and its usefulness in generating cross sections for light pseudoscalar mesons is investigated here. The soft part of the handbag model is first parametrized to fit well-known models of generalized parton distributions (GPD's), then cross sections are calculated directly from the GPD's. This is then directly extended to the calculation of neutrino cross sections for the production of the same type of light mesons.
Parton and valon distributions in the nucleon
Hwa, R.C.; Sajjad Zahir, M.
1981-06-01
Structure functions of the nucleon are analyzed in the valon model in which a nucleon is assumed to be a bound state of three valence quark clusters (valons). At high Q/sup 2/ the structure of the valons is described by leading-order results in the perturbative quantum chromodynamics. From the experimental data on deep-inelastic scattering off protons and neutrons, the flavor-dependent valon distributions in the nucleon are determined. Predictions for the parton distributions are then made for high Q/sup 2/ without guesses concerning the quark and gluon distributions at low Q/sup 2/. The sea-quark and gluon distributions are found to have a sharp peak at very small x. Convenient parametrization is provided which interpolates between different numbers of flavors.
Multiple model adaptive tracking of airborne targets
NASA Astrophysics Data System (ADS)
Norton, John E.
1988-12-01
Over the past ten years considerable work has been accomplished at the Air Force Institute of Technology (AFIT) towards improving the ability of tracking airborne targets. Motivated by the performance advantages in using established models of tracking environment variables within a Kalman filter, an advanced tracking algorithm has been developed based on adaptive estimation filter structures. A multiple model bank of filters that have been designed for various target dynamics, which each accounting for atmospheric disturbance of the Forward Looking Infrared (FLIR) sensor data and mechanical vibrations of the sensor platform, outperforms a correlator tracker. The bank of filters provides the estimation capability to guide the pointing mechanisms of a shared aperture laser/sensor system. The data is provided to the tracking algorithm via an (8 x 8)-pixel tracking Field of View (FOV) from the FLIR image plane. Data at each sample period is compared by an enhanced correlator to a target template. These offsets are measurements to a bank of linear Kalman filters which provide estimates of the target's location in azimuth and elevation coordinates based on a Gauss-Markov acceleration model, and a reduced form of the atmospheric jitter model for the disturbance in the IR wavefront carrying future measurements.
Model-based target and background characterization
NASA Astrophysics Data System (ADS)
Mueller, Markus; Krueger, Wolfgang; Heinze, Norbert
2000-07-01
Up to now most approaches of target and background characterization (and exploitation) concentrate solely on the information given by pixels. In many cases this is a complex and unprofitable task. During the development of automatic exploitation algorithms the main goal is the optimization of certain performance parameters. These parameters are measured during test runs while applying one algorithm with one parameter set to images that constitute of image domains with very different domain characteristics (targets and various types of background clutter). Model based geocoding and registration approaches provide means for utilizing the information stored in GIS (Geographical Information Systems). The geographical information stored in the various GIS layers can define ROE (Regions of Expectations) and may allow for dedicated algorithm parametrization and development. ROI (Region of Interest) detection algorithms (in most cases MMO (Man- Made Object) detection) use implicit target and/or background models. The detection algorithms of ROIs utilize gradient direction models that have to be matched with transformed image domain data. In most cases simple threshold calculations on the match results discriminate target object signatures from the background. The geocoding approaches extract line-like structures (street signatures) from the image domain and match the graph constellation against a vector model extracted from a GIS (Geographical Information System) data base. Apart from geo-coding the algorithms can be also used for image-to-image registration (multi sensor and data fusion) and may be used for creation and validation of geographical maps.
The impact of new neutrino DIS and Drell-Yan data on large-x parton distributions
J.F. Owens; J. Huston; C.E. Keppel; S. Kuhlmann; J.G. Morfin; F. Olness; J. Pumplin; D. Stump
2007-03-01
New data sets have recently become available for neutrino and antineutrino deep inelastic scattering on nuclear targets and for inclusive dimuon production in pp pd interactions. These data sets are sensitive to different combinations of parton distribution functions in the large-x region and, therefore, provide different constraints when incorporated into global parton distribution function fits. We compare and contrast the effects of these new data on parton distribution fits, with special emphasis on the effects at large x. The effects of the use of nuclear targets in the neutrino and antineutrino data sets are also investigated.
The Impact of new neutrino DIS and Drell-Yan data on large-x parton distributions
Owens, J.F.; Huston, J.; Keppel, C.E.; Kuhlmann, S.; Morfin, J.G.; Olness, F.; Pumplin, J.; Stump, D.; /Michigan State U.
2007-02-01
New data sets have recently become available for neutrino and antineutrino deep inelastic scattering on nuclear targets and for inclusive dimuon production in pp and pd interactions. These data sets are sensitive to different combinations of parton distribution functions in the large-x region and, therefore, provide different constraints when incorporated into global parton distribution function fits. We compare and contrast the effects of these new data on parton distribution fits, with special emphasis on the effects at large x. The effects of the use of nuclear targets in the neutrino and antineutrino data sets are also investigated.
Target & Propagation Models for the FINDER Radar
NASA Technical Reports Server (NTRS)
Cable, Vaughn; Lux, James; Haque, Salmon
2013-01-01
Finding persons still alive in piles of rubble following an earthquake, a severe storm, or other disaster is a difficult problem. JPL is currently developing a victim detection radar called FINDER (Finding Individuals in Emergency and Response). The subject of this paper is directed toward development of propagation & target models needed for simulation & testing of such a system. These models are both physical (real rubble piles) and numerical. Early results from the numerical modeling phase show spatial and temporal spreading characteristics when signals are passed through a randomly mixed rubble pile.
Disentangling correlations in multiple parton interactions
Calucci, G.; Treleani, D.
2011-01-01
Multiple Parton Interactions are the tool to obtain information on the correlations between partons in the hadron structure. Partons may be correlated in all degrees of freedom and all different correlation terms contribute to the cross section. The contributions due to the different parton flavors can be isolated, at least to some extent, by selecting properly the final state. In the case of high energy proton-proton collisions, the effects of correlations in the transverse coordinates and in fractional momenta are, on the contrary, unavoidably mixed in the final observables. The standard way to quantify the strength of double parton interactions is by the value of the effective cross section and a small value of the effective cross section may be originated both by the relatively short transverse distance between the pairs of partons undergoing the double interaction and by a large dispersion of the distribution in multiplicity of the multiparton distributions. The aim of the present paper is to show how the effects of longitudinal and transverse correlations may be disentangled by taking into account the additional information provided by double parton interactions in high energy proton-deuteron collisions.
Experimental overview of Generalized Parton Distribution results from HERMES
Zihlmann, B.
2009-08-04
Over the course of more than a decade the HERMES experiment has accumulated a wealth of data with electron and positron beams on various gaseous targets from Hydrogen up to Xenon. In addition, the beams and targets can be polarized. This data set is viewed in the context of Generalized Parton Distributions, a theoretical formalism with an explicit three dimensional view of the structure of the nucleon. It provides a link between experimental observables and the total angular momentum of the quarks in the nucleon.
First JAM results on the determination of polarized parton distributions
Accardi, Alberto; Jimenez-Delgado, Pedro; Melnitchouk, Wally
2014-01-01
The Jefferson Lab Angular Momentum (JAM) Collaboration is a new initiative to study the angular momentum dependent structure of the nucleon. First results on the determination of spin-dependent parton distribution functions at intermediate and large x from world data on polarized deep-inelastic scattering are presented. Different aspects of global QCD analysis are discussed, including the effects of nuclear structure of deuterium and {sup 3}He targets, target mass corrections and higher twist contributions to the g{sub 1} and g{sub 2} structure functions.
Working Group I: Parton distributions: Summary report for the HERA LHC Workshop Proceedings
Dittmar, M.; Forte, S.; Glazov, A.; Moch, S.; Alekhin, S.; Altarelli, G.; Andersen, Jeppe R.; Ball, R.D.; Blumlein, J.; Bottcher, H.; Carli, T.; Ciafaloni, M.; Colferai, D.; Cooper-Sarkar, A.; Corcella, G.; Del Debbio, L.; Dissertori, G.; Feltesse, J.; Guffanti, A.; Gwenlan, C.; Huston, J.; /Zurich, ETH /DESY, Zeuthen /Serpukhov, IHEP /CERN /Rome III U. /INFN, Rome3 /Cambridge U. /Edinburgh U. /Florence U. /INFN, Florence /Oxford U. /DSM, DAPNIA, Saclay /Michigan State U. /Uppsala U. /Barcelona U., ECM /Podgorica U. /Turin U. /INFN, Turin /Harish-Chandra Res. Inst. /Fermilab /Hamburg U., Inst. Theor. Phys. II
2005-11-01
We provide an assessment of the impact of parton distributions on the determination of LHC processes, and of the accuracy with which parton distributions (PDFs) can be extracted from data, in particular from current and forthcoming HERA experiments. We give an overview of reference LHC processes and their associated PDF uncertainties, and study in detail W and Z production at the LHC.We discuss the precision which may be obtained from the analysis of existing HERA data, tests of consistency of HERA data from different experiments, and the combination of these data. We determine further improvements on PDFs which may be obtained from future HERA data (including measurements of F{sub L}), and from combining present and future HERA data with present and future hadron collider data. We review the current status of knowledge of higher (NNLO) QCD corrections to perturbative evolution and deep-inelastic scattering, and provide reference results for their impact on parton evolution, and we briefly examine non-perturbative models for parton distributions. We discuss the state-of-the art in global parton fits, we assess the impact on them of various kinds of data and of theoretical corrections, by providing benchmarks of Alekhin and MRST parton distributions and a CTEQ analysis of parton fit stability, and we briefly presents proposals for alternative approaches to parton fitting. We summarize the status of large and small x resummation, by providing estimates of the impact of large x resummation on parton fits, and a comparison of different approaches to small x resummation, for which we also discuss numerical techniques.
Target space supersymmetric sigma model techniques
de Boer, Jan; Skenderis, Kostas
1996-07-01
We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet.
Pre-equilibrium parton dynamics: Proceedings
Wang, Xin-Nian
1993-12-31
This report contains papers on the following topics: parton production and evolution; QCD transport theory; interference in the medium; QCD and phase transition; and future heavy ion experiments. This papers have been indexed separately elsewhere on the data base.
Delineating parton distributions and the strong coupling
Jimenez-Delgado, P.; Reya, E.
2014-04-29
In this study, global fits for precision determinations of parton distributions, together with the highly correlated strong coupling αs, are presented up to next-to-next-to- leading order (NNLO) of QCD utilizing most world data (charm and jet production data are used where theoretically possible), except Tevatron gauge boson production data and LHC data which are left for genuine predictions. This is done within the 'dynamical' (valencelike input at Q02 = 0.8 GeV2 ) and 'standard' (input at Q02 = 2 GeV2) approach. The stability and reliability of the results are ensured by including nonperturbative higher-twist terms, nuclear corrections as well asmore » target mass corrections, and by applying various (Q2, W2) cuts on available data. In addition, the Q02 dependence of the results is studied in detail. Predictions are given, in particular for LHC, on gauge and Higgs boson as well as for top-quark pair production. At NNLO the dynamical approach results in αs(MZ2) = 0.1136 ± 0.0004, whereas the somewhat less constrained standard fit gives αs(MZ2) = 0.1162 ± 0.0006.« less
NIRATAM-NATO infrared air target model
NASA Astrophysics Data System (ADS)
Noah, Meg A.; Kristl, Joseph; Schroeder, John W.; Sandford, B. P.
1991-08-01
NIRATAM (the NATO Infrared Air Target Model) was developed by the NATO AC 243, Panel IV, Research Study Group 6 (RSG-6). RSG-6 is composed of representatives from Denmark, France, Germany, Italy, the Netherlands, the United Kingdom, the United States of America, and Canada (as an observer). NIRATAM is based on theoretical studies, field measurements, and infrared data analysis performed over many years. The model encompasses all the major signature components required to simulate the infrared signature of an aircraft and the atmosphere. The vehicle fuselage, facet, model includes radiation due to aerodynamic heating, internal heat sources, reflected sky, earth, and solar radiation. Plume combustion gas emissions are calculated for H(subscript 2)O, CO(subscript 2), CO, and other gases as well as solid particles. Lowtran 7 is used for the atmospheric transmission and radiance. The software generates graphical outputs of the target wireframe, plume flowfield, atmospheric transmission, total signature, and plume signature. Imagery data can be used for system development and evaluation. NIRATAM can be used for many applications such as measurement planning, data analysis, systems design, and aircraft development. Ontar has agreed to assist the RSG-6 by being the NIRATAM distribution center in the United States for users approved by the national representatives. Arrangements have also been made to distribute a user-friendly NIRATAM interface. This paper describes the model, presents results, makes comparisons with measured field data, and describes the availability and procedure for obtaining the software.
Parton physics on a Euclidean lattice.
Ji, Xiangdong
2013-06-28
I show that the parton physics related to correlations of quarks and gluons on the light cone can be studied through the matrix elements of frame-dependent, equal-time correlators in the large momentum limit. This observation allows practical calculations of parton properties on a Euclidean lattice. As an example, I demonstrate how to recover the leading-twist quark distribution by boosting an equal-time correlator to a large momentum. PMID:23848864
The midpoint between dipole and parton showers
NASA Astrophysics Data System (ADS)
Höche, Stefan; Prestel, Stefan
2015-09-01
We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A weighting algorithm is implemented that allows one to consistently treat potentially negative values of the splitting functions and the parton distributions. We provide two independent, publicly available implementations for the two event generators P ythia and S herpa.
The midpoint between dipole and parton showers
Höche, Stefan; Prestel, Stefan
2015-09-28
We present a new parton-shower algorithm. Borrowing from the basic ideas of dipole cascades, the evolution variable is judiciously chosen as the transverse momentum in the soft limit. This leads to a very simple analytic structure of the evolution. A weighting algorithm is implemented that allows one to consistently treat potentially negative values of the splitting functions and the parton distributions. Thus, we provide two independent, publicly available implementations for the two event generators PYTHIA and SHERPA.
Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production
Isenhower, L.D.; Sadler, M.E.; Towell, R.S.; Willis, J.L.; Geesaman, D.F.; Kaufman, S.B.; Mueller, B.A.; Reimer, P.E.; Brown, C.N.; Cooper, W.E.; He, X.C.; Lee, W.M.; Petitt, G.; Kaplan, D.M.; Carey, T.A.; Garvey, G.T.; Hawker, E.A.; Leitch, M.J.; McGaughey, P.L.; Moss, J.M.; Peng, J.C.; Reimer, P.E.; Sondheim, W.E.; Towell, R.S.; Beddo, M.E.; Chang, T.H.; Papavassiliou, V.; Webb, J.C.; Stankus, P.W.; Young, G.R.; Vasiliev, M.A.; Gagliardi, C.A.; Hawker, E.A.; Tribble, R.E.; Koetke, D.D.
1999-09-01
A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/{ital c} proton beam incident on Be, Fe, and W targets is reported. The behavior of the Drell-Yan ratios at small target-parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross-section ratios as a function of the incident-parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus. {copyright} {ital 1999} {ital The American Physical Society}
Multiple photon production in double parton scattering at the LHC
NASA Astrophysics Data System (ADS)
Palota da Silva, R.; Brenner Mariotto, C.; Goncalves, V. P.
2016-04-01
The high density of gluons in the initial state of hadronic collisions at LHC implies that the probability of multiple parton interactions within one proton-proton collision increases. In particular, the probability of having two or more hard interactions in a collision is not significantly suppressed with respect to the single interaction probability. In this contribution we study for the first time the production of prompt photons in double parton scattering processes. In particular, we estimate the rapidity distribution for the double Compton process, which leads to two photons plus two jets in the final state. Besides, we study the production of three and four photons in the final state, which are backgrounds to physics beyond the Standard Model.
Double Parton Fragmentation Function and its Evolution in Quarkonium Production
NASA Astrophysics Data System (ADS)
Kang, Zhong-Bo
2014-01-01
We summarize the results of a recent study on a new perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum pT at collider energies. Such a new factorization formalism includes both the leading power (LP) and next-to-leading power (NLP) contributions to the cross section in the mQ2/p_T^2 expansion for heavy quark mass mQ. For the NLP contribution, the so-called double parton fragmentation functions are involved, whose evolution equations have been derived. We estimate fragmentation functions in the non-relativistic QCD formalism, and found that their contribution reproduce the bulk of the large enhancement found in explicit NLO calculations in the color singlet model. Heavy quarkonia produced from NLP channels prefer longitudinal polarization, in contrast to the single parton fragmentation function. This might shed some light on the heavy quarkonium polarization puzzle.
Modeling unmanned system collaborative target engagement
NASA Astrophysics Data System (ADS)
Jaenisch, Holger M.; Handley, James W.; Hicklen, Michael L.
2007-04-01
This paper describes a novel algorithm for collaborative target engagement by unmanned systems (UMS) resulting in emergent behavior. We demonstrate UMS collaborative engagement using a simulation testbed model of a road, convoy vehicles traveling along the road, a squadron of unmanned aerial vehicles (UAVs), and multiple unmanned ground vehicles (UGVs) which are set to detonate when within close proximity to a convoy vehicle. No explicit artificial intelligence or swarming algorithms were used. Collision avoidance was an intrinsic phenomena. All entities acted independently throughout the simulation, but were given similar local instructions for possible courses of action (COAs) depending on current situations. Our algorithm and results are summarized in this paper.
Transverse nucleon structure and diagnostics of hard parton-parton processes at LHC
L. Frankfurt, M. Strikman, C. Weiss
2011-03-01
We propose a new method to determine at what transverse momenta particle production in high-energy pp collisions is governed by hard parton-parton processes. Using information on the transverse spatial distribution of partons obtained from hard exclusive processes in ep/\\gamma p scattering, we evaluate the impact parameter distribution of pp collisions with a hard parton-parton process as a function of p_T of the produced parton (jet). We find that the average pp impact parameters in such events depend very weakly on p_T in the range 2 < p_T < few 100 GeV, while they are much smaller than those in minimum-bias inelastic collisions. The impact parameters in turn govern the observable transverse multiplicity in such events (in the direction perpendicular to the trigger particle or jet). Measuring the transverse multiplicity as a function of p_T thus provides an effective tool for determining the minimum p_T for which a given trigger particle originates from a hard parton-parton process.
A statistical approach for polarized parton distributions
NASA Astrophysics Data System (ADS)
Bourrely, C.; Soffer, J.; Buccella, F.
2002-04-01
A global next-to-leading order QCD analysis of unpolarized and polarized deep-inelastic scattering data is performed with parton distributions constructed in a statistical physical picture of the nucleon. The chiral properties of QCD lead to strong relations between quarks and antiquarks distributions and the importance of the Pauli exclusion principle is also emphasized. We obtain a good description, in a broad range of x and Q^2, of all measured structure functions in terms of very few free parameters. We stress the fact that at RHIC-BNL the ratio of the unpolarized cross sections for the production of W^+ and W^- in pp collisions will directly probe the behavior of the bar d(x) / bar u(x) ratio for x ≥ 0.2, a definite and important test for the statistical model. Finally, we give specific predictions for various helicity asymmetries for the W^±, Z production in pp collisions at high energies, which will be measured with forthcoming experiments at RHIC-BNL and which are sensitive tests of the statistical model for Δ bar u(x) and Δ bar d(x).
New limits on intrinsic charm in the nucleon from global analysis of parton distributions
Jimenez-Delgado, P.; Hobbs, T. J.; Londergan, J. T.; Melnitchouk, W.
2015-02-27
We present a new global QCD analysis of parton distribution functions, allowing for possible intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high-energy scattering data for Q2 ≥ 1 GeV2 and W2 ≥ 3.5 GeV2, including fixed-target proton and deuteron deep cross sections at lower energies that were excluded in previously global analyses. The expanded data set places more stringent constraints on the momentum carried by IC, with (x)IC at most 0.5% (corresponding to an IC normalization of ~1%) at the 4σ level for ΔX2 = 1.more » We also assess the impact of older EMC measurements of Fc2c at large x, which favor a nonzero IC, but with very large X2 values.« less
Chiral dynamics and partonic structure at large transverse distances
Mark Strikman, Christian Weiss
2009-12-01
We study large-distance contributions to the nucleon's parton densities in the transverse coordinate (impact parameter) representation based on generalized parton distributions (GPDs). Chiral dynamics generates a distinct component of the partonic structure, located at momentum fractions x ~< M_pi / M_N and transverse distances b ~ 1/M_pi. We calculate this component using phenomenological pion exchange with a physical lower limit in b (the transverse ``core'' radius estimated from the nucleon's axial form factor, R_core = 0.55 fm) and demonstrate its universal character. This formulation preserves the basic picture of the ``pion cloud'' model of the nucleon's sea quark distributions, while restricting its application to the region actually governed by chiral dynamics. It is found that (a) the large-distance component accounts for only ~1/3 of the measured antiquark flavor asymmetry dbar - ubar at x ~ 0.1; (b) the strange sea quarks, s and sbar, are significantly more localized than the light antiquark sea; (c) the nucleon's singlet quark size for x < 0.1 is larger than its gluonic size, average(b^2)_{q + qbar} > average(b^2)_g, as suggested by the t-slopes of deeply-virtual Compton scattering and exclusive J/psi production measured at HERA and FNAL. We show that our approach reproduces the general N_c-scaling of parton densities in QCD, thanks to the degeneracy of N and Delta intermediate states in the large-N_c limit. We also comment on the role of pionic configurations at large longitudinal distances and the limits of their applicability at small x.
Recent progress on nuclear parton distribution functions
NASA Astrophysics Data System (ADS)
Hirai, M.; Kumano, S.; Saito, K.
2011-09-01
We report current status of global analyses on nuclear parton distribution functions (NPDFs). The optimum NPDFs are determined by analyzing high-energy nuclear reaction data. Due to limited experimental measurements, antiquark modifications have large uncertainties at x > 0.2 and gluon modifications cannot be determined. A nuclear modification difference between u and d quark distributions could be an origin of the long-standing NuTeV sin2θw anomaly. There is also an issue of nuclear modification differences between the structure functions of charged-lepton and neutrino reactions. Next, nuclear clustering effects are discussed in structure functions F2A as a possible explanation for an anomalous result in the 9Be nucleus at the Thomas Jefferson National Accelerator Facility (JLab). Last, tensor-polarized quark and antiquark distribution functions are extracted from HERMES data on the polarized structure function b1 of the deuteron, and they could be used for testing theoretical models and for proposing future experiments, for example, the one at JLab. Such measurements could open a new field of spin physics in spin-one hadrons.
A Search Model for Imperfectly Detected Targets
NASA Technical Reports Server (NTRS)
Ahumada, Albert
2012-01-01
Under the assumptions that 1) the search region can be divided up into N non-overlapping sub-regions that are searched sequentially, 2) the probability of detection is unity if a sub-region is selected, and 3) no information is available to guide the search, there are two extreme case models. The search can be done perfectly, leading to a uniform distribution over the number of searches required, or the search can be done with no memory, leading to a geometric distribution for the number of searches required with a success probability of 1/N. If the probability of detection P is less than unity, but the search is done otherwise perfectly, the searcher will have to search the N regions repeatedly until detection occurs. The number of searches is thus the sum two random variables. One is N times the number of full searches (a geometric distribution with success probability P) and the other is the uniform distribution over the integers 1 to N. The first three moments of this distribution were computed, giving the mean, standard deviation, and the kurtosis of the distribution as a function of the two parameters. The model was fit to the data presented last year (Ahumada, Billington, & Kaiwi, 2 required to find a single pixel target on a simulated horizon. The model gave a good fit to the three moments for all three observers.
Constraints on parton distribution from CDF
Bodek, A.; CDF Collaboration
1995-10-01
The asymmetry in W{sup -} - W{sup +} production in p{bar p} collisions and Drell-Yan data place tight constraints on parton distributions functions. The W asymmetry data constrain the slope of the quark distribution ratio d(x)/u(x) in the x range 0.007-0.27. The published W asymmetry results from the CDF 1992.3 data ({approx} 20 pb{sup -1}) greatly reduce the systematic error originating from the choice of PDF`s in the W mass measurement at CDF. These published results have also been included in the CTEQ3, MRSA, and GRV94 parton distribution fits. These modern parton distribution functions axe still in good agreement with the new 1993-94 CDF data({approx} 108 pb{sup -1} combined). Preliminary results from CDF for the Drell-Yan cross section in the mass range 11-350 GeV/c{sup 2} are discussed.
On the internal target model in a tracking task
NASA Technical Reports Server (NTRS)
Caglayan, A. K.; Baron, S.
1981-01-01
An optimal control model for predicting operator's dynamic responses and errors in target tracking ability is summarized. The model, which predicts asymmetry in the tracking data, is dependent on target maneuvers and trajectories. Gunners perception, decision making, control, and estimate of target positions and velocity related to crossover intervals are discussed. The model provides estimates for means, standard deviations, and variances for variables investigated and for operator estimates of future target positions and velocities.
Studies of Partonic Transverse Momentum and Spin Structure of the Nucleon at HERMES
Contalbrigo, Marco
2011-10-21
The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. At the HERMES experiment, azimuthal single-spin asymmetries of pions and charged kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons off a transversely (polarized) hydrogen and deuterium target have been measured. Such asymmetries provide new insights on crucial aspects of the parton dynamics. By measuring various hadron types in the initial and final states, flavor sensitivity is achieved. Evidence is reported of the poorly known transversity function and of naive-T-odd transverse-momentum-dependent parton distribution functions related to spin-orbit effects. Evidence of spin-orbit effects in quark fragmentation is also observed, which are opposite in sign for favored and disfavored processes.
Parton Propagation and Fragmentation in QCD Matter
Alberto Accardi, Francois Arleo, William Brooks, David D'Enterria, Valeria Muccifora
2009-12-01
We review recent progress in the study of parton propagation, interaction and fragmentation in both cold and hot strongly interacting matter. Experimental highlights on high-energy hadron production in deep inelastic lepton-nucleus scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan processes in hadron-nucleus collisions are presented. The existing theoretical frameworks for describing the in-medium interaction of energetic partons and the space-time evolution of their fragmentation into hadrons are discussed and confronted to experimental data. We conclude with a list of theoretical and experimental open issues, and a brief description of future relevant experiments and facilities.
Evolution of parton fragmentation functions at finitetemperature
Osborne, Jonathan; Wang, Enke; Wang, Xin-Nian
2002-06-12
The first order correction to the parton fragmentation functions in a thermal medium is derived in the leading logarithmic approximation in the framework of thermal field theory. The medium-modified evolution equations of the parton fragmentation functions are also derived. It is shown that all infrared divergences, both linear and logarithmic, in the real processes are canceled among themselves and by corresponding virtual corrections. The evolution of the quark number and the energy loss (or gain) induced by the thermal medium are investigated.
Triple parton scattering in collinear approximation of perturbative QCD
NASA Astrophysics Data System (ADS)
Snigirev, A. M.
2016-08-01
Revised formulas for the inclusive cross section of a triple parton scattering process in a hadron collision are suggested based on the modified collinear three-parton distributions. The possible phenomenological issues are discussed.
Target Recognition Using Neural Networks for Model Deformation Measurements
NASA Technical Reports Server (NTRS)
Ross, Richard W.; Hibler, David L.
1999-01-01
Optical measurements provide a non-invasive method for measuring deformation of wind tunnel models. Model deformation systems use targets mounted or painted on the surface of the model to identify known positions, and photogrammetric methods are used to calculate 3-D positions of the targets on the model from digital 2-D images. Under ideal conditions, the reflective targets are placed against a dark background and provide high-contrast images, aiding in target recognition. However, glints of light reflecting from the model surface, or reduced contrast caused by light source or model smoothness constraints, can compromise accurate target determination using current algorithmic methods. This paper describes a technique using a neural network and image processing technologies which increases the reliability of target recognition systems. Unlike algorithmic methods, the neural network can be trained to identify the characteristic patterns that distinguish targets from other objects of similar size and appearance and can adapt to changes in lighting and environmental conditions.
Tradeoffs among watershed model calibration targets for parameter estimation
Hydrologic models are commonly calibrated by optimizing a single objective function target to compare simulated and observed flows, although individual targets are influenced by specific flow modes. Nash-Sutcliffe efficiency (NSE) emphasizes flood peaks in evaluating simulation f...
Fragmentation of parton jets at small x
Kirschner, R.
1985-08-01
The parton fragmentation function is calculated in the region of small x in the doubly logarithmic approximation of QCD. For this, the method of separating the softest particle, which has hitherto been applied only in the Regge kinematic region, is developed. Simple arguments based on unitarity and gauge invariance are used to derive the well known condition of ordering of the emission angles.
Progress in the dynamical parton distributions
Jimenez-Delgado, Pedro
2012-06-01
The present status of the (JR) dynamical parton distribution functions is reported. Different theoretical improvements, including the determination of the strange sea input distribution, the treatment of correlated errors and the inclusion of alternative data sets, are discussed. Highlights in the ongoing developments as well as (very) preliminary results in the determination of the strong coupling constant are presented.
Systematic Improvement of QCD Parton Showers
Winter, Jan; Hoeche, Stefan; Hoeth, Hendrik; Krauss, Frank; Schonherr, Marek; Zapp, Korinna; Schumann, Steffen; Siegert, Frank; /Freiburg U.
2012-05-17
In this contribution, we will give a brief overview of the progress that has been achieved in the field of combining matrix elements and parton showers. We exemplify this by focusing on the case of electron-positron collisions and by reporting on recent developments as accomplished within the SHERPA event generation framework.
Examining the Crossover from the Hadronic to Partonic Phase in QCD
Xu Mingmei; Yu Meiling; Liu Lianshou
2008-03-07
A mechanism, consistent with color confinement, for the transition between perturbative and physical vacua during the gradual crossover from the hadronic to partonic phase is proposed. The essence of this mechanism is the appearance and growing up of a kind of grape-shape perturbative vacuum inside the physical one. A percolation model based on simple dynamics for parton delocalization is constructed to exhibit this mechanism. The crossover from hadronic matter to sQGP (strongly coupled quark-gluon plasma) as well as the transition from sQGP to weakly coupled quark-gluon plasma with increasing temperature is successfully described by using this model.
Modeling projectile impact onto prestressed ceramic targets
NASA Astrophysics Data System (ADS)
Holmquist, T. J.; Johnson, G. R.
2003-09-01
This work presents computed results for the responses of ceramic targets, with and without prestress, subjected to projectile impact. Also presented is a computational technique to include prestress. Ceramic materials have been considered for armor applications for many years because of their high strength and low density. Many researchers have demonstrated that providing confinement enhances the ballistic performance of ceramic targets. More recently, prestressing the ceramic is being considered as an additional enhancement technique. This work investigates the effect of prestressing the ceramic for both thin and thick target configurations subjected to projectile impact. In all cases the targets with ceramic prestress provided enhanced ballistic performance. The computed results indicate that prestressed ceramic reduces and/or delays failure, resulting in improved ceramic performance and ballistic efficiency.
Spatial frequency dependence of target signature for infrared performance modeling
NASA Astrophysics Data System (ADS)
Du Bosq, Todd; Olson, Jeffrey
2011-05-01
The standard model used to describe the performance of infrared imagers is the U.S. Army imaging system target acquisition model, based on the targeting task performance metric. The model is characterized by the resolution and sensitivity of the sensor as well as the contrast and task difficulty of the target set. The contrast of the target is defined as a spatial average contrast. The model treats the contrast of the target set as spatially white, or constant, over the bandlimit of the sensor. Previous experiments have shown that this assumption is valid under normal conditions and typical target sets. However, outside of these conditions, the treatment of target signature can become the limiting factor affecting model performance accuracy. This paper examines target signature more carefully. The spatial frequency dependence of the standard U.S. Army RDECOM CERDEC Night Vision 12 and 8 tracked vehicle target sets is described. The results of human perception experiments are modeled and evaluated using both frequency dependent and independent target signature definitions. Finally the function of task difficulty and its relationship to a target set is discussed.
Studies of transverse momentum dependent parton distributions and Bessel weighting
Aghasyan, M.; Avakian, H.; De Sanctis, E.; Gamberg, L.; Mirazita, M.; Musch, B.; Prokudin, A.; Rossi, P.
2015-03-01
In this paper we present a new technique for analysis of transverse momentum dependent parton distribution functions, based on the Bessel weighting formalism. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. Using a fully differential cross section for the process, the effect of four momentum conservation is analyzed using various input models for transverse momentum distributions and fragmentation functions. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Monte Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy/Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.
Studies of transverse momentum dependent parton distributions and Bessel weighting
Aghasyan, M.; Avakian, H.; De Sanctis, E.; Gamberg, L.; Mirazita, M.; Musch, B.; Prokudin, A.; Rossi, P.
2015-03-01
In this paper we present a new technique for analysis of transverse momentum dependent parton distribution functions, based on the Bessel weighting formalism. The procedure is applied to studies of the double longitudinal spin asymmetry in semi-inclusive deep inelastic scattering using a new dedicated Monte Carlo generator which includes quark intrinsic transverse momentum within the generalized parton model. Using a fully differential cross section for the process, the effect of four momentum conservation is analyzed using various input models for transverse momentum distributions and fragmentation functions. We observe a few percent systematic offset of the Bessel-weighted asymmetry obtained from Montemore » Carlo extraction compared to input model calculations, which is due to the limitations imposed by the energy and momentum conservation at the given energy/Q2. We find that the Bessel weighting technique provides a powerful and reliable tool to study the Fourier transform of TMDs with controlled systematics due to experimental acceptances and resolutions with different TMD model inputs.« less
Transorbital target localization in the porcine model
NASA Astrophysics Data System (ADS)
DeLisi, Michael P.; Mawn, Louise A.; Galloway, Robert L.
2013-03-01
Current pharmacological therapies for the treatment of chronic optic neuropathies such as glaucoma are often inadequate due to their inability to directly affect the optic nerve and prevent neuron death. While drugs that target the neurons have been developed, existing methods of administration are not capable of delivering an effective dose of medication along the entire length of the nerve. We have developed an image-guided system that utilizes a magnetically tracked flexible endoscope to navigate to the back of the eye and administer therapy directly to the optic nerve. We demonstrate the capabilities of this system with a series of targeted surgical interventions in the orbits of live pigs. Target objects consisted of NMR microspherical bulbs with a volume of 18 μL filled with either water or diluted gadolinium-based contrast, and prepared with either the presence or absence of a visible coloring agent. A total of 6 pigs were placed under general anesthesia and two microspheres of differing color and contrast content were blindly implanted in the fat tissue of each orbit. The pigs were scanned with T1-weighted MRI, image volumes were registered, and the microsphere containing gadolinium contrast was designated as the target. The surgeon was required to navigate the flexible endoscope to the target and identify it by color. For the last three pigs, a 2D/3D registration was performed such that the target's coordinates in the image volume was noted and its location on the video stream was displayed with a crosshair to aid in navigation. The surgeon was able to correctly identify the target by color, with an average intervention time of 20 minutes for the first three pigs and 3 minutes for the last three.
Understanding target delineation using simple probabilistic modelling
NASA Astrophysics Data System (ADS)
Willis, Chris J.
2015-10-01
Performance assessment is carried out for a simple target delineation process based on thresholding and shape fitting. The method uses the information contained in Receiver Operating Characteristic curves together with basic observations regarding target sizes and shapes. Performance is gauged by considering the delineations that might result from having particular arrangements of detected pixels within the vicinity of a hypothesized target. In particular, the method considers the qualities of delineations generated when having various combinations of detected pixels at a number of locations around the inner and outer boundaries of the underlying object. Three distinct types of arrangement for pixels on the inner target boundary are considered. Each has the potential to lead to a good quality delineation in a thresholding and shape fitting scheme. The deleterious effect of false alarms within the surrounding local region is also taken into account. The resulting ensembles of detected pixels are treated using familiar rules for combination to form probabilities for the delineations as a whole. Example results are produced for simple target prototypes in cluttered SAR imagery.
Ma, Guo -Liang; Bzdak, Adam
2014-11-04
In this study, we show that the incoherent elastic scattering of partons, as present in a multi-phase transport model (AMPT), with a modest parton–parton cross-section of σ = 1.5 – 3 mb, naturally explains the long-range two-particle azimuthal correlation as observed in proton–proton and proton–nucleus collisions at the Large Hadron Collider.
NASA Astrophysics Data System (ADS)
Lindenbaum, S. J.; Longacre, R. S.
2008-11-01
In an earlier paper we developed a QCD-inspired theoretical parton bubble model (PBM) for RHIC/LHC. The motivation for the PBM was to develop a model that would reasonably quantitatively agree with the strong charged particle pair correlations observed by the STAR Collaboration at RHIC in Au+Au central collisions at sNN=200 GeV in the transverse momentum range 0.8 to 2.0 GeV/c. The model was constructed to also agree with the Hanbury Brown and Twiss (HBT) observed small final-state source size ~2 fm radii in the transverse momentum range above 0.8 GeV/c. The model assumed a substructure of a ring of localized adjoining ~2 fm radius bubbles perpendicular to the collider beam direction, centered on the beam, at midrapidity. The bubble ring was assumed to be located on the expanding fireball surface of the Au+Au collision. These bubbles consist almost entirely of gluons and form gluonic hot spots on the fireball surface. We achieved a reasonable quantitative agreement with the results of both the physically significant charge-independent (CI) and charge-dependent (CD) correlations that were observed. In this paper we extend the model to include the changing development of bubbles with centrality from the most central region where bubbles are very important to the most peripheral where the bubbles are gone. Energy density is found to be related to bubble formation and as centrality decreases the maximum energy density and bubbles shift from symmetry around the beam axis to the reaction plane region, causing a strong correlation of bubble formation with elliptic flow. We find reasonably quantitative agreement (within a few percent of the total correlations) with a new precision RHIC experiment that extended the centrality region investigated to the range 0% 80% (most central to most peripheral). The characteristics and behavior of the bubbles imply they represent a significant substructure formed on the surface of the fireball at kinetic freezeout.
Generalized parton distributions and exclusive processes
Guzey, Vadim
2013-10-01
In last fifteen years, GPDs have emerged as a powerful tool to reveal such aspects of the QCD structure of the nucleon as: - 3D parton correlations and distributions; - spin content of the nucleon. Further advances in the field of GPDs and hard exclusive processes rely on: - developments in theory and new methods in phenomenology such as new flexible parameterizations, neural networks, global QCD fits - new high-precision data covering unexplored kinematics: JLab at 6 and 12 GeV, Hermes with recoil detector, Compass, EIC. This slide-show presents: Nucleon structure in QCD, particularly hard processes, factorization and parton distributions; and a brief overview of GPD phenomenology, including basic properties of GPDs, GPDs and QCD structure of the nucleon, and constraining GPDs from experiments.
Nucleon Form Factors from Generalized Parton Distributions
M. Guidal; Maxim Polyakov; Anatoly Radyushkin; Marc Vanderhaeghen
2004-10-01
We discuss the links between Generalized Parton Distributions (GPDs) and elastic nucleon form factors. These links, in the form of sum rules, represent powerful constraints on parametrizations of GPDs. A Regge parametrization for GPDs at small momentum transfer, is extended to the large momentum transfer region and it is found to describe the basic features of proton and neutron electromagnetic form factor data. This parametrization is used to estimate the quark contribution to the nucleon spin.
Generalized Parton Distributions from Lattice QCD
Orginos, Konstantinos
2007-10-01
I review recent results on moments of Generalized Parton Distribution functions (GPDs) from Lattice QCD. In particular, I discuss the methodology of lattice calculations, and how various systematic errors arising in these calculations are controlled. I conclude with an overview of the roadmap towards precision non-perturbative determination of moments of GPDs, and discuss the potential impact to the extraction of GPDs form experiment.
Hohlraum Modeling of Hybrid Shock Ignition Target
NASA Astrophysics Data System (ADS)
Dodd, E. S.; Baumgaertel, J. A.; Loomis, E. N.
2014-10-01
Hybrid Shock Ignition (HSI) combines a hohlraum driven capsule with a directly driven shock for heating. Unlike standard Shock Ignition, the capsule is imploded with X-rays from a laser driven hohlraum to compress the fuel, which is too cold to ignite. However, as in Shock Ignition, the compressed fuel is subsequently heated to ignition temperatures with a directly-driven shock. The use of indirect and direct drive in the same target necessitates complex beam geometry, and thus HSI is being pursued with spherical hohlraums. More importantly for the NIF, the beam repointing required for polar direct drive will not be needed for the implosion phase with this target. Spherical hohlraums have been fielded previously at the OMEGA laser as a part of the Tetrahedral Hohlraum Campaign. They were originally proposed as an alternative to cylindrical hohlraums to achieve highly symmetric radiation drive. The new HSI hohlraums will require six laser entrance holes in hexahedral symmetry to accommodate all beams. This presentation will show radiation-hydrodynamic calculations of the current hexahedral OMEGA hohlraum design, as well as benchmark calculations of the old tetrahedral targets. Supported under the US DOE by the Los Alamos National Security, LLC under Contract DE-AC52-06NA25396. LA-UR-14-24945.
Yao, Zhi-Jiang; Dong, Jie; Che, Yu-Jing; Zhu, Min-Feng; Wen, Ming; Wang, Ning-Ning; Wang, Shan; Lu, Ai-Ping; Cao, Dong-Sheng
2016-05-01
Drug-target interactions (DTIs) are central to current drug discovery processes and public health fields. Analyzing the DTI profiling of the drugs helps to infer drug indications, adverse drug reactions, drug-drug interactions, and drug mode of actions. Therefore, it is of high importance to reliably and fast predict DTI profiling of the drugs on a genome-scale level. Here, we develop the TargetNet server, which can make real-time DTI predictions based only on molecular structures, following the spirit of multi-target SAR methodology. Naïve Bayes models together with various molecular fingerprints were employed to construct prediction models. Ensemble learning from these fingerprints was also provided to improve the prediction ability. When the user submits a molecule, the server will predict the activity of the user's molecule across 623 human proteins by the established high quality SAR model, thus generating a DTI profiling that can be used as a feature vector of chemicals for wide applications. The 623 SAR models related to 623 human proteins were strictly evaluated and validated by several model validation strategies, resulting in the AUC scores of 75-100 %. We applied the generated DTI profiling to successfully predict potential targets, toxicity classification, drug-drug interactions, and drug mode of action, which sufficiently demonstrated the wide application value of the potential DTI profiling. The TargetNet webserver is designed based on the Django framework in Python, and is freely accessible at http://targetnet.scbdd.com . PMID:27167132
Metrics for image-based modeling of target acquisition
NASA Astrophysics Data System (ADS)
Fanning, Jonathan D.
2012-06-01
This paper presents an image-based system performance model. The image-based system model uses an image metric to compare a given degraded image of a target, as seen through the modeled system, to the set of possible targets in the target set. This is repeated for all possible targets to generate a confusion matrix. The confusion matrix is used to determine the probability of identifying a target from the target set when using a particular system in a particular set of conditions. The image metric used in the image-based model should correspond closely to human performance. The image-based model performance is compared to human perception data on Contrast Threshold Function (CTF) tests, naked eye Triangle Orientation Discrimination (TOD), and TOD including an infrared camera system. Image-based system performance modeling is useful because it allows modeling of arbitrary image processing. Modern camera systems include more complex image processing, much of which is nonlinear. Existing linear system models, such as the TTP metric model implemented in NVESD models such as NV-IPM, assume that the entire system is linear and shift invariant (LSI). The LSI assumption makes modeling nonlinear processes difficult, such as local area processing/contrast enhancement (LAP/LACE), turbulence reduction, and image fusion.
J. J. Sakurai Prize for Theoretical Particle Physics Talk: Partons, QCD, and Factorization
NASA Astrophysics Data System (ADS)
Soper, Davison
2009-05-01
Many important cross sections in high-energy collisions are analyzed using factorization properties. I review the nature of factorization, how it arose from the parton model, and current issues in its development. This talk will be coordinated with the one by Collins.
Multiple parton scattering in nuclei: Beyond helicity amplitude approximation
Zhang, Ben-Wei; Wang, Xin-Nian
2003-01-21
Multiple parton scattering and induced parton energy loss in deeply inelastic scattering (DIS) off heavy nuclei is studied within the framework of generalized factorization in perturbative QCD with a complete calculation beyond the helicity amplitude (or soft bremsstrahlung) approximation. Such a calculation gives rise to new corrections to the modified quark fragmentation functions. The effective parton energy loss is found to be reduced by a factor of 5/6 from the result of helicity amplitude approximation.
Self-Organizing Maps and Parton Distribution Functions
K. Holcomb, Simonetta Liuti, D. Z. Perry
2011-05-01
We present a new method to extract parton distribution functions from high energy experimental data based on a specific type of neural networks, the Self-Organizing Maps. We illustrate the features of our new procedure that are particularly useful for an anaysis directed at extracting generalized parton distributions from data. We show quantitative results of our initial analysis of the parton distribution functions from inclusive deep inelastic scattering.
Monte Carlo modeling of spallation targets containing uranium and americium
NASA Astrophysics Data System (ADS)
Malyshkin, Yury; Pshenichnov, Igor; Mishustin, Igor; Greiner, Walter
2014-09-01
Neutron production and transport in spallation targets made of uranium and americium are studied with a Geant4-based code MCADS (Monte Carlo model for Accelerator Driven Systems). A good agreement of MCADS results with experimental data on neutron- and proton-induced reactions on 241Am and 243Am nuclei allows to use this model for simulations with extended Am targets. It was demonstrated that MCADS model can be used for calculating the values of critical mass for 233,235U, 237Np, 239Pu and 241Am. Several geometry options and material compositions (U, U + Am, Am, Am2O3) are considered for spallation targets to be used in Accelerator Driven Systems. All considered options operate as deep subcritical targets having neutron multiplication factor of k∼0.5. It is found that more than 4 kg of Am can be burned in one spallation target during the first year of operation.
Studies of partonic transverse momentum and spin structure of the nucleon
NASA Astrophysics Data System (ADS)
Contalbrigo, M.
2014-06-01
The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. The Thomas Jefferson National Laboratory, after the CEBAF upgrade to 12 GeV, will become the most complete facility for the investigation of the hadron structure in the valence region by scattering of polarized electron off various polarized nucleon targets. A compendium of the planned experiments is here presented.
J.W. Negele; R.C. Brower; P. Dreher; R. Edwards; G. Fleming; Ph. Hagler; U.M. Heller; Th. Lippert; A.V.Pochinsky; D.B. Renner; D. Richards; K. Schilling; W. Schroers
2004-04-01
This talk presents recent calculations in full QCD of the lowest three moments of generalized parton distributions and the insight they provide into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon. In addition, new exploratory calculations in the chiral regime of full QCD are discussed.
Global QCD Analysis of Polarized Parton Densities
Stratmann, Marco
2009-08-04
We focus on some highlights of a recent, first global Quantum Chromodynamics (QCD) analysis of the helicity parton distributions of the nucleon, mainly the evidence for a rather small gluon polarization over a limited region of momentum fraction and for interesting flavor patterns in the polarized sea. It is examined how the various sets of data obtained in inclusive and semi-inclusive deep inelastic scattering and polarized proton-proton collisions help to constrain different aspects of the quark, antiquark, and gluon helicity distributions. Uncertainty estimates are performed using both the robust Lagrange multiplier technique and the standard Hessian approach.
A Tutorial on Target-Mediated Drug Disposition (TMDD) Models
Dua, P; Hawkins, E; van der Graaf, PH
2015-01-01
Target-mediated drug disposition (TMDD) is the phenomenon in which a drug binds with high affinity to its pharmacological target site (such as a receptor) to such an extent that this affects its pharmacokinetic characteristics.1 The aim of this Tutorial is to provide an introductory guide to the mathematical aspects of TMDD models for pharmaceutical researchers. Examples of Berkeley Madonna2 code for some models discussed in this Tutorial are provided in the Supplementary Materials. PMID:26225261
Wideband radar signal modeling of ground moving targets in clutter
NASA Astrophysics Data System (ADS)
Malas, John A.; Pasala, Krishna M.; Westerkamp, John J.
2002-08-01
Research in the area of air-to-ground target detection, track and identification (ID) requires the development of target signal models for known geometric shapes moving in ground clutter. Space-time adaptive filtering techniques in particular make good use of temporal-spatial synthetic radar signal return data. A radar signal model is developed to generate synthetic wideband radar signal data for use in multi-channel adaptive signal processing.
Automated target recognition using passive radar and coordinated flight models
NASA Astrophysics Data System (ADS)
Ehrman, Lisa M.; Lanterman, Aaron D.
2003-09-01
Rather than emitting pulses, passive radar systems rely on illuminators of opportunity, such as TV and FM radio, to illuminate potential targets. These systems are particularly attractive since they allow receivers to operate without emitting energy, rendering them covert. Many existing passive radar systems estimate the locations and velocities of targets. This paper focuses on adding an automatic target recognition (ATR) component to such systems. Our approach to ATR compares the Radar Cross Section (RCS) of targets detected by a passive radar system to the simulated RCS of known targets. To make the comparison as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. The estimated positions become inputs for an algorithm that uses a coordinated flight model to compute probable aircraft orientation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of several potential target classes as they execute the estimated maneuvers. The RCS is then scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. The Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern, so that the RCS can be further scaled. The Rician model compares the RCS of the illuminated aircraft with those of the potential targets. This comparison results in target identification.
Georeferenced model simulations efficiently support targeted monitoring
NASA Astrophysics Data System (ADS)
Berlekamp, Jürgen; Klasmeier, Jörg
2010-05-01
The European Water Framework Directive (WFD) demands the good ecological and chemical status of surface waters. To meet the definition of good chemical status of the WFD surface water concentrations of priority pollutants must not exceed established environmental quality standards (EQS). Surveillance of the concentrations of numerous chemical pollutants in whole river basins by monitoring is laborious and time-consuming. Moreover, measured data do often not allow for immediate source apportionment which is a prerequisite for defining promising reduction strategies to be implemented within the programme of measures. In this context, spatially explicit model approaches are highly advantageous because they provide a direct link between local point emissions (e.g. treated wastewater) or diffuse non-point emissions (e.g. agricultural runoff) and resulting surface water concentrations. Scenario analyses with such models allow for a priori investigation of potential positive effects of reduction measures such as optimization of wastewater treatment. The geo-referenced model GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers) has been designed to calculate spatially resolved averaged concentrations for different flow conditions (e.g. mean or low flow) based on emission estimations for local point source emissions such as treated effluents from wastewater treatment plants. The methodology was applied to selected pharmaceuticals (diclofenac, sotalol, metoprolol, carbamazepin) in the Main river basin in Germany (approx. 27,290 km²). Average concentrations of the compounds were calculated for each river reach in the whole catchment. Simulation results were evaluated by comparison with available data from orienting monitoring and used to develop an optimal monitoring strategy for the assessment of water quality regarding micropollutants at the catchment scale.
Modelling of dynamic targeting in the Air Operations Centre
NASA Astrophysics Data System (ADS)
Lo, Edward H. S.; Au, T. Andrew
2007-12-01
Air Operations Centres (AOCs) are high stress multitask environments for planning and executing of theatre-wide airpower. Operators have multiple responsibilities to ensure that the orchestration of air assets is coordinated to maximum effect. AOCs utilise a dynamic targeting process to immediately prosecute time-sensitive targets. For this process to work effectively, a timely decision must be made regarding the appropriate course of action before the action is enabled. A targeting solution is typically developed using a number of inter-related processes in the kill chain - the Find, Fix, Track, Target, Engage, and Assess (F2T2EA) model. The success of making a right decision about dynamic targeting is ultimately limited by the cognitive and cooperative skills of the team prosecuting the mission and their associated workload. This paper presents a model of human interaction and tasks within the dynamic targeting sequence. The complex network of tasks executed by the team can be analysed by undertaking simulation of the model to identify possible information-processing bottlenecks and overloads. The model was subjected to various tests to generate typical outcomes, operator utilisation, duration as well as rates of output in the dynamic targeting process. This capability will allow for future "what-if" evaluations of numerous concepts for team formation or task reallocation, complementing live exercises and experiments.
Experimental consistency in parton distribution fitting
Pumplin, Jon
2010-04-01
The recently developed 'data set diagonalization' method is applied to measure compatibility of the data sets that are used to determine parton distribution functions. Discrepancies among the experiments are found to be somewhat larger than is predicted by propagating the published experimental errors according to Gaussian statistics. The results support a tolerance criterion of {Delta}{chi}{sup 2{approx_equal}}10 to estimate the 90% confidence range for parton distribution function uncertainties. No basis is found in the data sets for the larger {Delta}{chi}{sup 2} values that are in current use, though it may be necessary to retain those larger values until improved methods can be developed to take account of systematic errors in applying the theory, including the effect of parametrization dependence. The data set diagonalization method also measures how much influence each experiment has on the global fit and identifies experiments that show significant tension with respect to the others. The method is used to explore the contribution from muon scattering experiments, which are found to exhibit the largest discrepancies in the current fit.
Excited nucleon as a van der Waals system of partons
Jenkovszky, L. L.; Muskeyev, A. O. Yezhov, S. N.
2012-06-15
Saturation in deep inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) is associated with a phase transition between the partonic gas, typical of moderate x and Q{sup 2}, and partonic fluid appearing at increasing Q{sup 2} and decreasing Bjorken x. We suggest the van der Waals equation of state to describe properly this phase transition.
Nucleon Generalized Parton Distributions from Full Lattice QCD
Robert Edwards; Philipp Haegler; David Richards; John Negele; Konstantinos Orginos; Wolfram Schroers; Jonathan Bratt; Andrew Pochinsky; Michael Engelhardt; George Fleming; Bernhard Musch; Dru Renner
2007-07-03
We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N_f=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)^3.
The parton orbital angular momentum: Status and prospects
NASA Astrophysics Data System (ADS)
Liu, Keh-Fei; Lorcé, Cédric
2016-06-01
Theoretical progress on the formulation and classification of the quark and gluon orbital angular momenta (OAM) is reviewed. Their relation to parton distributions and open questions and puzzles are discussed. We give a status report on the lattice calculation of the parton kinetic and canonical OAM and point out several strategies to calculate the quark and gluon canonical OAM on the lattice.
Parton Charge Symmetry Violation: Electromagnetic Effects and W Production Asymmetries
J.T. Londergan; D.P. Murdock; A.W. Thomas
2006-04-14
Recent phenomenological work has examined two different ways of including charge symmetry violation in parton distribution functions. First, a global phenomenological fit to high energy data has included charge symmetry breaking terms, leading to limits on the magnitude of parton charge symmetry breaking. In a second approach, two groups have included the coupling of partons to photons in the QCD evolution equations. One possible experiment that could search for isospin violation in parton distributions is a measurement of the asymmetry in W production at a collider. In this work we include both of the postulated sources of parton charge symmetry violation. We show that, given charge symmetry violation of a magnitude consistent with existing high energy data, the expected W production asymmetries would be quite small, generally less than one percent.
Modeling the effects of contrast enhancement on target acquisition performance
NASA Astrophysics Data System (ADS)
Du Bosq, Todd W.; Fanning, Jonathan D.
2008-04-01
Contrast enhancement and dynamic range compression are currently being used to improve the performance of infrared imagers by increasing the contrast between the target and the scene content, by better utilizing the available gray levels either globally or locally. This paper assesses the range-performance effects of various contrast enhancement algorithms for target identification with well contrasted vehicles. Human perception experiments were performed to determine field performance using contrast enhancement on the U.S. Army RDECOM CERDEC NVESD standard military eight target set using an un-cooled LWIR camera. The experiments compare the identification performance of observers viewing linearly scaled images and various contrast enhancement processed images. Contrast enhancement is modeled in the US Army thermal target acquisition model (NVThermIP) by changing the scene contrast temperature. The model predicts improved performance based on any improved target contrast, regardless of feature saturation or enhancement. To account for the equivalent blur associated with each contrast enhancement algorithm, an additional effective MTF was calculated and added to the model. The measured results are compared with the predicted performance based on the target task difficulty metric used in NVThermIP.
NASA Astrophysics Data System (ADS)
Geiger, Klaus
1997-08-01
VNI is a general-purpose Monte Carlo event generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. On the basis of renormalization-group improved parton description and quantum-kinetic theory, it uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme that is governed by the dynamics itself. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position space, momentum space and color space. The parton evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi) hard interactions in QCD, involving 2 → 2 parton collisions, 2 → 1 parton fusion processes, and 1 → 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. This article gives a brief review of the physics underlying VNI, which is followed by a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including a simple example), annotates input and control parameters, and discusses output data provided by it.
Statistical analysis of target acquisition sensor modeling experiments
NASA Astrophysics Data System (ADS)
Deaver, Dawne M.; Moyer, Steve
2015-05-01
The U.S. Army RDECOM CERDEC NVESD Modeling and Simulation Division is charged with the development and advancement of military target acquisition models to estimate expected soldier performance when using all types of imaging sensors. Two elements of sensor modeling are (1) laboratory-based psychophysical experiments used to measure task performance and calibrate the various models and (2) field-based experiments used to verify the model estimates for specific sensors. In both types of experiments, it is common practice to control or measure environmental, sensor, and target physical parameters in order to minimize uncertainty of the physics based modeling. Predicting the minimum number of test subjects required to calibrate or validate the model should be, but is not always, done during test planning. The objective of this analysis is to develop guidelines for test planners which recommend the number and types of test samples required to yield a statistically significant result.
Generating target system specifications from a domain model using CLIPS
NASA Technical Reports Server (NTRS)
Sugumaran, Vijayan; Gomaa, Hassan; Kerschberg, Larry
1991-01-01
The quest for reuse in software engineering is still being pursued and researchers are actively investigating the domain modeling approach to software construction. There are several domain modeling efforts reported in the literature and they all agree that the components that are generated from domain modeling are more conducive to reuse. Once a domain model is created, several target systems can be generated by tailoring the domain model or by evolving the domain model and then tailoring it according to the specified requirements. This paper presents the Evolutionary Domain Life Cycle (EDLC) paradigm in which a domain model is created using multiple views, namely, aggregation hierarchy, generalization/specialization hierarchies, object communication diagrams and state transition diagrams. The architecture of the Knowledge Based Requirements Elicitation Tool (KBRET) which is used to generate target system specifications is also presented. The preliminary version of KBRET is implemented in the C Language Integrated Production System (CLIPS).
Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions
Jimenez-Delgado, Pedro; Accardi, Alberto; Melnitchouk, Wally
2014-02-01
We present the first results of a new global next-to-leading order analysis of spin-dependent parton distribution functions from the most recent world data on inclusive polarized deep-inelastic scattering, focusing in particular on the large-x and low-Q^2 regions. By directly fitting polarization asymmetries we eliminate biases introduced by using polarized structure function data extracted under nonuniform assumptions for the unpolarized structure functions. For analysis of the large-x data we implement nuclear smearing corrections for deuterium and 3He nuclei, and systematically include target mass and higher twist corrections to the g_1 and g_2 structure functions at low Q^2. We also explore the effects of Q^2 and W^2 cuts in the data sets, and the potential impact of future data on the behavior of the spin-dependent parton distributions at large x.
Target model and simulation for laser imaging fuze
NASA Astrophysics Data System (ADS)
Li, Weiheng; Song, Chengtian
2013-09-01
Image detection is an important direction of fuze development nowadays, and laser imaging fuze is one of the main technologies. This paper carries out the research in simulation technology of the process with detection, scan and imaging, which is used in laser imaging fuze for tank target, and get the simulation images information of different intersection conditions, including tank spot information，distance information and power information. The target coordinate system is established with the movement characteristics，physical characteristics and existing coordinate system of tank target. And through transferring missile coordinates to the target coordinate system as well as the relative movement between the different time intervals, the model of missile-target in time and space is build up. The model is build up according to the tank target and diffusion properties of different background, including desert, soil, vegetation, and buildings. The relations of scattering power and bidirectional reflectance distribution function deduced the laser echo power calculation formula, which can calculate the echoes incidence to each surface of the laser.The design of laser imaging fuze simulation system is complicated ,which contains the technology of the process with detection, scan and imaging used in laser imaging fuze for tank target. The simulation system products the tank spot picture, the distance gradation picture, and the power gradation picture. The latter two contains two-dimensional information, the scanning distance as well as the value of echo power to meet the expected design effects.
Rapid SAR target modeling through genetic inheritance mechanism
NASA Astrophysics Data System (ADS)
Bala, Jerzy; Pachowicz, Peter W.; Vafaie, Halleh
1997-07-01
The paper presents a methodology and GETP experimental system for rapid SAR target signature generation from limited initial sensory data. The methodology exploits and integrates the following four processes: (1) analysis of initial SAR image signatures and their transformation into higher-level blob representation, (2) blob modeling, (3) genetic inheritance modeling to generate new instances of a target model in blob representation, and (4) synthesis of new SAR signatures from genetically evolved blob data. The GETP system takes several SAR signatures of the target and transforms each signature into more general scattered blob graphs, where each blob represents local energy cluster. A single graph node is describe by blob relative position, confidence, and iconic data. Graph data is forwarded to the genetic modeling process while blob image is stored in a catalog. Genetic inheritance is applied to the initial population of graph data. New graph models of the target are generated and evaluated. Selected graph variations are forwarded to the synthesis process. The synthesis process restores target signature from a given graph and a catalog of blobs. The background is synthesized to complement the signature. Initial experimental results are illustrated with 64 X 32 image sections of a tank.
Lappi, T.; Venugopalan, R.; Mantysaari, H.
2015-02-25
We argue that the proton multiplicities measured in Roman pot detectors at an electron ion collider can be used to determine centrality classes in incoherent diffractive scattering. Incoherent diffraction probes the fluctuations in the interaction strengths of multi-parton Fock states in the nuclear wavefunctions. In particular, the saturation scale that characterizes this multi-parton dynamics is significantly larger in central events relative to minimum bias events. As an application, we examine the centrality dependence of incoherent diffractive vector meson production. We identify an observable which is simultaneously very sensitive to centrality triggered parton fluctuations and insensitive to details of the model.
HELAC-PHEGAS: A generator for all parton level processes
NASA Astrophysics Data System (ADS)
Cafarella, Alessandro; Papadopoulos, Costas G.; Worek, Malgorzata
2009-10-01
The updated version of the HELAC-PHEGAS event generator is presented. The matrix elements are calculated through Dyson-Schwinger recursive equations using color connection representation. Phase-space generation is based on a multichannel approach, including optimization. HELAC-PHEGAS generates parton level events with all necessary information, in the most recent Les Houches Accord format, for the study of any process within the Standard Model in hadron and lepton colliders. New version program summaryProgram title: HELAC-PHEGAS Catalogue identifier: ADMS_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADMS_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 35 986 No. of bytes in distributed program, including test data, etc.: 380 214 Distribution format: tar.gz Programming language: Fortran Computer: All Operating system: Linux Classification: 11.1, 11.2 External routines: Optionally Les Houches Accord (LHA) PDF Interface library ( http://projects.hepforge.org/lhapdf/) Catalogue identifier of previous version: ADMS_v1_0 Journal reference of previous version: Comput. Phys. Comm. 132 (2000) 306 Does the new version supersede the previous version?: Yes, partly Nature of problem: One of the most striking features of final states in current and future colliders is the large number of events with several jets. Being able to predict their features is essential. To achieve this, the calculations need to describe as accurately as possible the full matrix elements for the underlying hard processes. Even at leading order, perturbation theory based on Feynman graphs runs into computational problems, since the number of graphs contributing to the amplitude grows as n!. Solution method: Recursive algorithms based on Dyson-Schwinger equations have been developed recently in
New limits on intrinsic charm in the nucleon from global analysis of parton distributions
Jimenez-Delgado, P.; Hobbs, T. J.; Londergan, J. T.; Melnitchouk, W.
2015-02-27
We present a new global QCD analysis of parton distribution functions, allowing for possible intrinsic charm (IC) contributions in the nucleon inspired by light-front models. The analysis makes use of the full range of available high-energy scattering data for Q^{2} ≥ 1 GeV_{2} and W^{2} ≥ 3.5 GeV^{2}, including fixed-target proton and deuteron deep cross sections at lower energies that were excluded in previously global analyses. The expanded data set places more stringent constraints on the momentum carried by IC, with (x)_{IC} at most 0.5% (corresponding to an IC normalization of ~1%) at the 4σ level for Δ_{X2} = 1. We also assess the impact of older EMC measurements of F^{c}_{2}c at large x, which favor a nonzero IC, but with very large X^{2} values.
Dynamic model of target charging by short laser pulse interactions.
Poyé, A; Dubois, J-L; Lubrano-Lavaderci, F; D'Humières, E; Bardon, M; Hulin, S; Bailly-Grandvaux, M; Ribolzi, J; Raffestin, D; Santos, J J; Nicolaï, Ph; Tikhonchuk, V
2015-10-01
A model providing an accurate estimate of the charge accumulation on the surface of a metallic target irradiated by a high-intensity laser pulse of fs-ps duration is proposed. The model is confirmed by detailed comparisons with specially designed experiments. Such a model is useful for understanding the electromagnetic pulse emission and the quasistatic magnetic field generation in laser-plasma interaction experiments. PMID:26565356
Dynamic model of target charging by short laser pulse interactions
NASA Astrophysics Data System (ADS)
Poyé, A.; Dubois, J.-L.; Lubrano-Lavaderci, F.; D'Humières, E.; Bardon, M.; Hulin, S.; Bailly-Grandvaux, M.; Ribolzi, J.; Raffestin, D.; Santos, J. J.; Nicolaï, Ph.; Tikhonchuk, V.
2015-10-01
A model providing an accurate estimate of the charge accumulation on the surface of a metallic target irradiated by a high-intensity laser pulse of fs-ps duration is proposed. The model is confirmed by detailed comparisons with specially designed experiments. Such a model is useful for understanding the electromagnetic pulse emission and the quasistatic magnetic field generation in laser-plasma interaction experiments.
Deeply exclusive processes and generalized parton distributions
Marc Vanderhaegen
2005-02-01
We discuss how generalized parton distributions (GPDs) enter into hard exclusive processes, and focuses on the links between GPDs and elastic nucleon form factors. These links, in the form of sum rules, represent powerful constraints on parameterizations of GPDs. A Regge parameterization for the GPDs at small momentum transfer -t is extended to the large-t region and it is found to catch the basic features of proton and neutron electromagnetic form factor data. This parameterization allows to estimate the quark contribution to the nucleon spin. It is furthermore discussed how these GPDs at large-t enter into two-photon exchange processes and resolve the discrepancy between Rosenbluth and polarization experiments of elastic electron nucleon scattering.
Pion valence-quark parton distribution function
NASA Astrophysics Data System (ADS)
Chang, Lei; Thomas, Anthony W.
2015-10-01
Within the Dyson-Schwinger equation formulation of QCD, a rainbow ladder truncation is used to calculate the pion valence-quark distribution function (PDF). The gap equation is renormalized at a typical hadronic scale, of order 0.5 GeV, which is also set as the default initial scale for the pion PDF. We implement a corrected leading-order expression for the PDF which ensures that the valence-quarks carry all of the pion's light-front momentum at the initial scale. The scaling behavior of the pion PDF at a typical partonic scale of order 5.2 GeV is found to be (1 - x) ν, with ν ≃ 1.6, as x approaches one.
Evolution effects on parton energy loss with detailed balance
Cheng Luan; Wang Enke
2010-07-15
The initial conditions in the chemically nonequilibrated medium and Bjorken expanding medium at Relativistic Heavy Ion Collider (RHIC) are determined. With a set of rate equations describing the chemical equilibration of quarks and gluons based on perturbative QCD, we investigate the consequence for parton evolution at RHIC. With considering parton evolution, it is shown that the Debye screening mass and the inverse mean free-path of gluons reduce with increasing proper time in the QGP medium. The parton evolution affects the parton energy loss with detailed balance, both parton energy loss from stimulated emission in the chemically nonequilibrated expanding medium and in Bjorken expanding medium are linear dependent on the propagating distance rather than square dependent in the static medium. The energy absorption cannot be neglected at intermediate jet energies and small propagating distance of the energetic parton in contrast with that it is important only at intermediate jet energy in the static medium. This will increase the energy and propagating distance dependence of the parton energy loss and will affect the shape of suppression of moderately high P{sub T} hadron spectra.
Double Parton Scattering and 3D Proton Structure: A Light-Front Analysis
NASA Astrophysics Data System (ADS)
Rinaldi, Matteo; Scopetta, Sergio; Traini, Marco; Vento, Vicente
2016-06-01
Double parton scattering, occurring in high energy hadron-hadron collisions, e.g. at the LHC, is usually investigated through model dependent analyses of the so called effective cross section {σ_{eff}}. We present a dynamic approach to this fundamental quantity making use of a Light-Front model treatment. Within such a framework {σ_{eff}} is initially evaluated at low energy scale using the model and then, through QCD evolution, at high energy scale to reach the experimental conditions. Our numerical outcomes are consistent with the present experimental analyses of data in kinematical region we investigate. An important result of the present work is the {x_i} dependence of {σ_{eff}}, a feature directly connected to double parton correlations and which could unveil new information on the three dimensional structure of the proton.
Some Perspectives on Network Modeling in Therapeutic Target Prediction
Albert, Reka; DasGupta, Bhaskar; Mobasheri, Nasim
2013-01-01
Drug target identification is of significant commercial interest to pharmaceutical companies, and there is a vast amount of research done related to the topic of therapeutic target identification. Interdisciplinary research in this area involves both the biological network community and the graph algorithms community. Key steps of a typical therapeutic target identification problem include synthesizing or inferring the complex network of interactions relevant to the disease, connecting this network to the disease-specific behavior, and predicting which components are key mediators of the behavior. All of these steps involve graph theoretical or graph algorithmic aspects. In this perspective, we provide modelling and algorithmic perspectives for therapeutic target identification and highlight a number of algorithmic advances, which have gotten relatively little attention so far, with the hope of strengthening the ties between these two research communities. PMID:25288898
Precision Modeling Of Targets Using The VALUE Computer Program
NASA Astrophysics Data System (ADS)
Hoffman, George A.; Patton, Ronald; Akerman, Alexander
1989-08-01
The 1976-vintage LASERX computer code has been augmented to produce realistic electro-optical images of targets. Capabilities lacking in LASERX but recently incorporated into its VALUE successor include: •Shadows cast onto the ground •Shadows cast onto parts of the target •See-through transparencies (e.g.,canopies) •Apparent images due both to atmospheric scattering and turbulence •Surfaces characterized by multiple bi-directional reflectance functions VALUE provides not only realistic target modeling by its precise and comprehensive representation of all target attributes, but additionally VALUE is very user friendly. Specifically, setup of runs is accomplished by screen prompting menus in a sequence of queries that is logical to the user. VALUE also incorporates the Optical Encounter (OPEC) software developed by Tricor Systems,Inc., Elgin, IL.
Modelling hot electron generation in short pulse target heating experiments
NASA Astrophysics Data System (ADS)
Sircombe, N. J.; Hughes, S. J.
2013-11-01
Target heating experiments planned for the Orion laser facility, and electron beam driven fast ignition schemes, rely on the interaction of a short pulse high intensity laser with dense material to generate a flux of energetic electrons. It is essential that the characteristics of this electron source are well known in order to inform transport models in radiation hydrodynamics codes and allow effective evaluation of experimental results and forward modelling of future campaigns. We present results obtained with the particle in cell (PIC) code EPOCH for realistic target and laser parameters, including first and second harmonic light. The hot electron distributions are characterised and their implications for onward transport and target heating are considered with the aid of the Monte-Carlo transport code THOR.
Optical model calculations of heavy-ion target fragmentation
NASA Technical Reports Server (NTRS)
Townsend, L. W.; Wilson, J. W.; Cucinotta, F. A.; Norbury, J. W.
1986-01-01
The fragmentation of target nuclei by relativistic protons and heavy ions is described within the context of a simple abrasion-ablation-final-state interaction model. Abrasion is described by a quantum mechanical formalism utilizing an optical model potential approximation. Nuclear charge distributions of the excited prefragments are calculated by both a hypergeometric distribution and a method based upon the zero-point oscillations of the giant dipole resonance. Excitation energies are estimated from the excess surface energy resulting from the abrasion process and the additional energy deposited by frictional spectator interactions of the abraded nucleons. The ablation probabilities are obtained from the EVA-3 computer program. Isotope production cross sections for the spallation of copper targets by relativistic protons and for the fragmenting of carbon targets by relativistic carbon, neon, and iron projectiles are calculated and compared with available experimental data.
Modeling target acquisition tasks associated with security and surveillance
NASA Astrophysics Data System (ADS)
Vollmerhausen, Richard; Robinson, Aaron L.
2007-07-01
Military sensor applications include tasks such as the surveillance of activity and searching for roadside explosives. These tasks involve identifying and tracking specific objects in a cluttered scene. Unfortunately, the probability of accomplishing these tasks is not predicted by the traditional detect, recognize, and identify (DRI) target acquisition models. The reason why many security and surveillance tasks are functionally different from the traditional DRI tasks is described. Experiments using characters and simple shapes illustrate the problem with using the DRI model to predict the probability of identifying individual objects. The current DRI model is extended to predict specific object identification by including the frequency spectrum content of target contrast. The predictions of the new model match experimental data.
Active imaging system performance model for target acquisition
NASA Astrophysics Data System (ADS)
Espinola, Richard L.; Teaney, Brian; Nguyen, Quang; Jacobs, Eddie L.; Halford, Carl E.; Tofsted, David H.
2007-04-01
The U.S. Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate has developed a laser-range-gated imaging system performance model for the detection, recognition, and identification of vehicle targets. The model is based on the established US Army RDECOM CERDEC NVESD sensor performance models of the human system response through an imaging system. The Java-based model, called NVLRG, accounts for the effect of active illumination, atmospheric attenuation, and turbulence effects relevant to LRG imagers, such as speckle and scintillation, and for the critical sensor and display components. This model can be used to assess the performance of recently proposed active SWIR systems through various trade studies. This paper will describe the NVLRG model in detail, discuss the validation of recent model components, present initial trade study results, and outline plans to validate and calibrate the end-to-end model with field data through human perception testing.
Using habitat suitability models to target invasive plant species surveys
Crall, Alycia W.; Jarnevich, Catherine S.; Panke, Brendon; Young, Nick; Renz, Mark; Morisette, Jeffrey
2013-01-01
Managers need new tools for detecting the movement and spread of nonnative, invasive species. Habitat suitability models are a popular tool for mapping the potential distribution of current invaders, but the ability of these models to prioritize monitoring efforts has not been tested in the field. We tested the utility of an iterative sampling design (i.e., models based on field observations used to guide subsequent field data collection to improve the model), hypothesizing that model performance would increase when new data were gathered from targeted sampling using criteria based on the initial model results. We also tested the ability of habitat suitability models to predict the spread of invasive species, hypothesizing that models would accurately predict occurrences in the field, and that the use of targeted sampling would detect more species with less sampling effort than a nontargeted approach. We tested these hypotheses on two species at the state scale (Centaurea stoebe and Pastinaca sativa) in Wisconsin (USA), and one genus at the regional scale (Tamarix) in the western United States. These initial data were merged with environmental data at 30-m2 resolution for Wisconsin and 1-km2 resolution for the western United States to produce our first iteration models. We stratified these initial models to target field sampling and compared our models and success at detecting our species of interest to other surveys being conducted during the same field season (i.e., nontargeted sampling). Although more data did not always improve our models based on correct classification rate (CCR), sensitivity, specificity, kappa, or area under the curve (AUC), our models generated from targeted sampling data always performed better than models generated from nontargeted data. For Wisconsin species, the model described actual locations in the field fairly well (kappa = 0.51, 0.19, P 2) = 47.42, P < 0.01). From these findings, we conclude that habitat suitability models can be
Method calibration of the model 13145 infrared target projectors
NASA Astrophysics Data System (ADS)
Huang, Jianxia; Gao, Yuan; Han, Ying
2014-11-01
The SBIR Model 13145 Infrared Target Projectors ( The following abbreviation Evaluation Unit ) used for characterizing the performances of infrared imaging system. Test items: SiTF, MTF, NETD, MRTD, MDTD, NPS. Infrared target projectors includes two area blackbodies, a 12 position target wheel, all reflective collimator. It provide high spatial frequency differential targets, Precision differential targets imaged by infrared imaging system. And by photoelectricity convert on simulate signal or digital signal. Applications software (IR Windows TM 2001) evaluate characterizing the performances of infrared imaging system. With regards to as a whole calibration, first differently calibration for distributed component , According to calibration specification for area blackbody to calibration area blackbody, by means of to amend error factor to calibration of all reflective collimator, radiance calibration of an infrared target projectors using the SR5000 spectral radiometer, and to analyze systematic error. With regards to as parameter of infrared imaging system, need to integrate evaluation method. According to regulation with -GJB2340-1995 General specification for military thermal imaging sets -testing parameters of infrared imaging system, the results compare with results from Optical Calibration Testing Laboratory . As a goal to real calibration performances of the Evaluation Unit.
Nonlinear sigma models with compact hyperbolic target spaces
NASA Astrophysics Data System (ADS)
Gubser, Steven; Saleem, Zain H.; Schoenholz, Samuel S.; Stoica, Bogdan; Stokes, James
2016-06-01
We explore the phase structure of nonlinear sigma models with target spaces corresponding to compact quotients of hyperbolic space, focusing on the case of a hyperbolic genus-2 Riemann surface. The continuum theory of these models can be approximated by a lattice spin system which we simulate using Monte Carlo methods. The target space possesses interesting geometric and topological properties which are reflected in novel features of the sigma model. In particular, we observe a topological phase transition at a critical temperature, above which vortices proliferate, reminiscent of the Kosterlitz-Thouless phase transition in the O(2) model [1, 2]. Unlike in the O(2) case, there are many different types of vortices, suggesting a possible analogy to the Hagedorn treatment of statistical mechanics of a proliferating number of hadron species. Below the critical temperature the spins cluster around six special points in the target space known as Weierstrass points. The diversity of compact hyperbolic manifolds suggests that our model is only the simplest example of a broad class of statistical mechanical models whose main features can be understood essentially in geometric terms.
CASP9 assessment of free modeling target predictions.
Kinch, Lisa; Yong Shi, Shuo; Cong, Qian; Cheng, Hua; Liao, Yuxing; Grishin, Nick V
2011-01-01
We present an overview of the ninth round of Critical Assessment of Protein Structure Prediction (CASP9) "Template free modeling" category (FM). Prediction models were evaluated using a combination of established structural and sequence comparison measures and a novel automated method designed to mimic manual inspection by capturing both global and local structural features. These scores were compared to those assigned manually over a diverse subset of target domains. Scores were combined to compare overall performance of participating groups and to estimate rank significance. Moreover, we discuss a few examples of free modeling targets to highlight the progress and bottlenecks of current prediction methods. Notably, a server prediction model for a single target (T0581) improved significantly over the closest structure template (44% GDT increase). This accomplishment represents the "winner" of the CASP9 FM category. A number of human expert groups submitted slight variations of this model, highlighting a trend for human experts to act as "meta predictors" by correctly selecting among models produced by the top-performing automated servers. The details of evaluation are available at http://prodata.swmed.edu/CASP9/ . PMID:21997521
Modeling astatine production in liquid lead-bismuth spallation targets
NASA Astrophysics Data System (ADS)
David, J. C.; Boudard, A.; Cugnon, J.; Ghali, S.; Leray, S.; Mancusi, D.; Zanini, L.
2013-03-01
Astatine isotopes can be produced in liquid lead-bismuth eutectic targets through proton-induced double charge exchange reactions on bismuth or in secondary helium-induced interactions. Models implemented into the most common high-energy transport codes generally have difficulties to correctly estimate their production yields as was shown recently by the ISOLDE Collaboration, which measured release rates from a lead-bismuth target irradiated by 1.4 and 1 GeV protons. In this paper, we first study the capability of the new version of the Liège intranuclear cascade model, INCL4.6, coupled to the deexcitation code ABLA07 to predict the different elementary reactions involved in the production of such isotopes through a detailed comparison of the model with the available experimental data from the literature. Although a few remaining deficiencies are identified, very satisfactory results are found, thanks in particular to improvements brought recently on the treatment of low-energy helium-induced reactions. The implementation of the models into MCNPX allows identifying the respective contributions of the different possible reaction channels in the ISOLDE case. Finally, the full simulation of the ISOLDE experiment is performed, taking into account the likely rather long diffusion time from the target, and compared with the measured diffusion rates for the different astatine isotopes, at the two studied energies, 1.4 and 1 GeV. The shape of the isotopic distribution is perfectly reproduced as well as the absolute release rates, assuming in the calculation a diffusion time between 5 and 10hours. This work finally shows that our model, thanks to the attention paid to the emission of high-energy clusters and to low-energy cluster induced reactions, can be safely used within MCNPX to predict isotopes with a charge larger than that of the target by two units in spallation targets, and, probably, more generally to isotopes created in secondary reactions induced by composite
Probing transverse momentum dependent parton distributions in charmonium and bottomonium production
NASA Astrophysics Data System (ADS)
Mukherjee, Asmita; Rajesh, Sangem
2016-03-01
We propose the study of unpolarized transverse momentum dependent gluon parton distributions as well as the effect of linearly polarized gluons on transverse momentum and rapidity distributions of J /ψ and ϒ production within the framework of transverse momentum dependent factorization employing a color evaporation model (CEM) in an unpolarized proton-proton collision. We estimate the transverse momentum and rapidity distributions of J /ψ and ϒ at LHCb, RHIC and AFTER energies using TMD evolution formalism.
Insight into nucleon structure from generalized parton distributions
J.W. Negele; R.C. Brower; P. Dreher; R. Edwards; G. Fleming; Ph. Hagler; Th. Lippert; A.V.Pochinsky; D.B. Renner; D. Richards; K. Schilling; W. Schroers
2004-03-01
The lowest three moments of generalized parton distributions are calculated in full QCD and provide new insight into the behavior of nucleon electromagnetic form factors, the origin of the nucleon spin, and the transverse structure of the nucleon.
Experimental studies of hadronization and parton propagation in SIDIS
NASA Astrophysics Data System (ADS)
Mineeva, Taisiya; CLAS Collaboration
2013-10-01
A wealth of new data has become available over the past decade from DESY, Jefferson lab, Fermilab, RHIC and LHC that connect hadron propagation and hadron formation. While Drell-Yan reaction and heavy-ion collions contribute different kinds of information of parton propagation in nuclear environment, the most direct information comes from DIS. Unique feature of semi-inclusive DIS is its ability to investigate time-dependence of handronization by embedding it in the nuclei of varying size. Such studies begun in late 70s in SLAC, and continued with HEMRES and Jefferson lab program. A series of measurements of neutral pion electroproduction, performed on deuterium, carbon, iron and lead targets exposed to a 5.014 GeV electron beam will be presented. The data were collected using the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The goal of the experiment was to measure attenuation of hadrons in a medium of varying size normalized to deuterium. We present preliminary three-fold multiplicity ratios of neutral pions in (ν, Q2, z) and (Q2, z, pT2)bins. Combined with extensive data on charged pion states, these data are providing new insights into hadronization mechanism.
Huston, Joey [Co-Spokesperson; Ownes, Joseph [Co-Spokesperson
The Coordinated Theoretical-Experimental Project on QCD is a multi-institutional collaboration devoted to a broad program of research projects and cooperative enterprises in high-energy physics centered on Quantum Chromodynamics (QCD) and its implications in all areas of the Standard Model and beyond. The Collaboration consists of theorists and experimentalists at 18 universities and 5 national laboratories. More than 65 sets of Parton Distribution Functions are available for public access. Links to many online software tools, information about Parton Distribution Functions, papers, and other resources are also available.
NUCLEAR REACTION MODELING FOR RIA ISOL TARGET DESIGN
S. MASHNIK; ET AL
2001-03-01
Los Alamos scientists are collaborating with researchers at Argonne and Oak Ridge on the development of improved nuclear reaction physics for modeling radionuclide production in ISOL targets. This is being done in the context of the MCNPX simulation code, which is a merger of MCNP and the LAHET intranuclear cascade code, and simulates both nuclear reaction cross sections and radiation transport in the target. The CINDER code is also used to calculate the time-dependent nuclear decays for estimating induced radioactivities. They give an overview of the reaction physics improvements they are addressing, including intranuclear cascade (INC) physics, where recent high-quality inverse-kinematics residue data from GSI have led to INC spallation and fission model improvements; and preequilibrium reactions important in modeling (p,xn) and (p,xnyp) cross sections for the production of nuclides far from stability.
Modeling of video compression effects on target acquisition performance
NASA Astrophysics Data System (ADS)
Cha, Jae H.; Preece, Bradley; Espinola, Richard L.
2009-05-01
The effect of video compression on image quality was investigated from the perspective of target acquisition performance modeling. Human perception tests were conducted recently at the U.S. Army RDECOM CERDEC NVESD, measuring identification (ID) performance on simulated military vehicle targets at various ranges. These videos were compressed with different quality and/or quantization levels utilizing motion JPEG, motion JPEG2000, and MPEG-4 encoding. To model the degradation on task performance, the loss in image quality is fit to an equivalent Gaussian MTF scaled by the Structural Similarity Image Metric (SSIM). Residual compression artifacts are treated as 3-D spatio-temporal noise. This 3-D noise is found by taking the difference of the uncompressed frame, with the estimated equivalent blur applied, and the corresponding compressed frame. Results show good agreement between the experimental data and the model prediction. This method has led to a predictive performance model for video compression by correlating various compression levels to particular blur and noise input parameters for NVESD target acquisition performance model suite.
CASP9 Assessment of Free Modeling Target Predictions
Kinch, Lisa; Shi, Shuo Yong; Cong, Qian; Cheng, Hua; Liao, Yuxing; Grishin, Nick V.
2011-01-01
We present an overview of the ninth round of Critical Assessment of Protein Structure Prediction (CASP9) ‘Template free modeling’ category (FM). Prediction models were evaluated using a combination of established structural and sequence comparison measures and a novel automated method designed to mimic manual inspection by capturing both global and local structural features. These scores were compared to those assigned manually over a diverse subset of target domains. Scores were combined to compare overall performance of participating groups and to estimate rank significance. Moreover, we discuss a few examples of free modeling targets to highlight the progress and bottlenecks of current prediction methods. Notably, a server prediction model for a single target (T0581) improved significantly over the closest structure template (44% GDT increase). This accomplishment represents the ‘winner’ of the CASP9 FM category. A number of human expert groups submitted slight variations of this model, highlighting a trend for human experts to act as “meta predictors” by correctly selecting among models produced by the top-performing automated servers. The details of evaluation are available at http://prodata.swmed.edu/CASP9/ PMID:21997521
Comparison of measured and modeled BRDF of natural targets
NASA Astrophysics Data System (ADS)
Boucher, Yannick; Cosnefroy, Helene; Petit, Alain D.; Serrot, Gerard; Briottet, Xavier
1999-07-01
The Bidirectional Reflectance Distribution Function (BRDF) plays a major role to evaluate or simulate the signatures of natural and artificial targets in the solar spectrum. A goniometer covering a large spectral and directional domain has been recently developed by the ONERA/DOTA. It was designed to allow both laboratory and outside measurements. The spectral domain ranges from 0.40 to 0.95 micrometer, with a resolution of 3 nm. The geometrical domain ranges 0 - 60 degrees for the zenith angle of the source and the sensor, and 0 - 180 degrees for the relative azimuth between the source and the sensor. The maximum target size for nadir measurements is 22 cm. The spatial target irradiance non-uniformity has been evaluated and then used to correct the raw measurements. BRDF measurements are calibrated thanks to a spectralon reference panel. Some BRDF measurements performed on sand and short grass and are presented here. Eight bidirectional models among the most popular models found in the literature have been tested on these measured data set. A code fitting the model parameters to the measured BRDF data has been developed. The comparative evaluation of the model performances is carried out, versus different criteria (root mean square error, root mean square relative error, correlation diagram . . .). The robustness of the models is evaluated with respect to the number of BRDF measurements, noise and interpolation.
Random and Targeted Interventions for Epidemic Control in Metapopulation Models
NASA Astrophysics Data System (ADS)
Tanaka, Gouhei; Urabe, Chiyori; Aihara, Kazuyuki
2014-07-01
In general, different countries and communities respond to epidemics in accordance with their own control plans and protocols. However, owing to global human migration and mobility, strategic planning for epidemic control measures through the collaboration of relevant public health administrations is gaining importance for mitigating and containing large-scale epidemics. Here, we present a framework to evaluate the effectiveness of random (non-strategic) and targeted (strategic) epidemic interventions for spatially separated patches in metapopulation models. For a random intervention, we analytically derive the critical fraction of patches that receive epidemic interventions, above which epidemics are successfully contained. The analysis shows that the heterogeneity of patch connectivity makes it difficult to contain epidemics under the random intervention. We demonstrate that, particularly in such heterogeneously connected networks, targeted interventions are considerably effective compared to the random intervention. Our framework is useful for identifying the target areas where epidemic control measures should be focused.
Brain Arteriovenous Malformation Modeling, Pathogenesis and Novel Therapeutic Targets
Chen, Wanqiu; Choi, Eun-Jung; McDougall, Cameron M.; Su, Hua
2014-01-01
Patients harboring brain arteriovenous malformation (bAVM) are at life-threatening risk of rupture and intracranial hemorrhage (ICH). The pathogenesis of bAVM has not been completely understood. Current treatment options are invasive and ≈ 20% of patients are not offered interventional therapy because of excessive treatment risk. There are no specific medical therapies to treat bAVMs. The lack of validated animal models has been an obstacle for testing hypotheses of bAVM pathogenesis and testing new therapies. In this review, we summarize bAVM model development; and bAVM pathogenesis and potential therapeutic targets that have been identified during model development. PMID:24723256
Target characterization using hidden Markov models and classifiers
Kil, D.H.; Shin, F.B.; Fricke, J.R.
1996-06-01
We investigate various projection spaces and extract key parameters or features from each space to characterize low-frequency active (LFA) target returns in a low-dimensional space. The projection spaces encompass (1) time-embedded phase map, (2) segmented matched filter output, (3) various time-frequency distribution functions, such as Reduced Interference Distribution, to capture time-varying echo signatures, and (4) principal component inversion for signal cleaning and characterization. We utilize both dynamic and static features and parameterize them with a hybrid classification methodology consisting of hidden Markov models, classifiers, and data fusion. This clue identification and evaluation process is complemented by concurrent work on target physics to enhance our understanding of the target echo formation process. As a function of target aspect, we can observe (1) back scatter dominated by axial n=0 modes propagating back and forth along the length of the shell, (2) direct scatter from shell discontinuities, (3) helical or creeping waves from phase matching between the acoustic waves and membrane waves (both shear and compressional), and (4) the ``array response`` of the shell, with coherent superposition of elemental scattering sites along the shell leading to a peak response near broadside. As a function of target structures (the empty shell and the ribbed/complex shells), we see considerable complexity brought about by multiple reflections of the membrane waves between the rings. We show the merit of fusing parameters estimated from these projection spaces in characterizing LFA target returns using the MIT/NRL scaled model data. Our hybrid classifiers outperform the matched filter-based recognizer by an average of 5-25%;. This improvement can be attributed to a combination of good features that maximize inter-class discrimination and appropriate classifier topologies that exploit the underlying multi-dimensional feature probability density function.
New observables for multiple-parton interactions measurements using Z +jets processes at the LHC
NASA Astrophysics Data System (ADS)
Kumar, R.; Bansal, M.; Bansal, S.; Singh, J. B.
2016-03-01
Multiple-parton interactions (MPI) play a vital role in hadron-hadron collisions. This paper presents a study of the MPIs with simulated Z +jets events in proton-proton collisions at a center-of-mass energy of 13 TeV. The events are simulated with powheg, followed by hadronization and parton showering using pythia8. The events with dimuon invariant mass in the range of 60 - 120 GeV /c2 are selected for the analysis. The charged particle jets having a minimum transverse momentum of 5 GeV /c and an absolute pseudorapidity less than 2 are used to construct the observables for measurements of the MPIs. The proposed observables and phase-space region presented in this paper are found to have enhanced sensitivity to MPIs. The increased sensitivity to MPIs will lead to precise constraints on the parameters of the MPI models.
Multiple parton interaction studies at DØ
Lincoln, D.
2016-04-01
Here, we present the results of studies of multiparton interactions done by the DØ collaboration using the Fermilab Tevatron at a center of mass energy of 1.96 TeV. We also present three analyses, involving three distinct final signatures: (a) a photon with at least 3 jets ( γ + 3jets), (b) a photon with a bottom or charm quark tagged jet and at least 2 other jets ( γ + b/c + 2jets), and (c) two J/ ψ mesons. The fraction of photon + jet events initiated by double parton scattering is about 20%, while the fraction for events inmore » which two J/ ψ mesons were produced is 30 ± 10. While the two measurements are statistically compatible, the difference might indicate differences in the quark and gluon distribution within a nucleon. Finally, this speculation originates from the fact that photon + jet events are created by collisions with quarks in the initial states, while J/ ψ events are produced preferentially by a gluonic initial state.« less
Nuclear parton distribution functions and their uncertainties
Hirai, M.; Kumano, S.; Nagai, T.-H.
2004-10-01
We analyze experimental data of nuclear structure-function ratios F{sub 2}{sup A}/F{sub 2}{sup A{sup '}} and Drell-Yan cross section ratios for obtaining optimum parton distribution functions (PDFs) in nuclei. Then, uncertainties of the nuclear PDFs are estimated by the Hessian method. Valence-quark distributions are determined by the F{sub 2} data at large x; however, the small-x part is not obvious from the data. On the other hand, the antiquark distributions are determined well at x{approx}0.01 from the F{sub 2} data and at x{approx}0.1 by the Drell-Yan data; however, the large-x behavior is not clear. Gluon distributions cannot be fixed by the present data and they have large uncertainties in the whole x region. Parametrization results are shown in comparison with the data. We provide a useful code for calculating nuclear PDFs at given x and Q{sup 2}.
Multivariate screening in food adulteration: untargeted versus targeted modelling.
López, M Isabel; Trullols, Esther; Callao, M Pilar; Ruisánchez, Itziar
2014-03-15
Two multivariate screening strategies (untargeted and targeted modelling) have been developed to compare their ability to detect food fraud. As a case study, possible adulteration of hazelnut paste is considered. Two different adulterants were studied, almond paste and chickpea flour. The models were developed from near-infrared (NIR) data coupled with soft independent modelling of class analogy (SIMCA) as a classification technique. Regarding the untargeted strategy, only unadulterated samples were modelled, obtaining 96.3% of correct classification. The prediction of adulterated samples gave errors between 5.5% and 2%. Regarding targeted modelling, two classes were modelled: Class 1 (unadulterated samples) and Class 2 (almond adulterated samples). Samples adulterated with chickpea were predicted to prove its ability to deal with non-modelled adulterants. The results show that samples adulterated with almond were mainly classified in their own class (90.9%) and samples with chickpea were classified in Class 2 (67.3%) or not in any class (30.9%), but no one only as unadulterated. PMID:24206702
The influence of the target strength model on computed perforation
Reaugh, J.E.
1993-06-01
The authors used an axi-symmetric, two-dimensional Eulerian computer simulation program to simulate the penetration of a tungsten rod with length to diameter ratio L/D = 10 into a thick steel target, and the same rod into finite steel plates of thicknesses between 0.9 and 1.3 L. They compare the perforation limit with the semi-infinite penetration depth at the same velocity (the excess thickness) when the model for target strength is constant yield stress, and when the model incorporates work hardening and thermal softening. The authors also compare their computed results with available experimental results, which show an excess thickness of about 1 rod diameter.
Nowak, Wolf-Dieter
2007-06-13
Results are reported on the transverse target-spin asymmetry (TTSA) associated with deeply virtual Compton scattering on the proton. The data have been accumulated in the years 2002-2004 by the HERMES experiment at DESY, in which the HERA 27.6 GeV e+ beam scattered on a transversely polarized hydrogen target. Two azimuthal amplitudes of the TTSA appearing to LO in 1/Q and {alpha}s, A{sub UT}{sup sin({phi}-{phi}{sub S})cos{phi}} and A{sub UT}{sup cos({phi} -{phi}{sub S})sin{phi}}, are given as a function of -t,xB,Q2 in the kinematic range |t| < 0.7 GeV2, 0.03 < xB < 0.35 and 1 < Q2 < 10 GeV2. The first amplitude is found to be sensitive to the generalized parton distribution (GPD) E of the proton, which can be parameterized in a GPD model through quark total angular momentum Jq(q = u, d). Within the context of this model, a constraint in the (Ju,Jd) plane is obtained from HERMES TTSA data.
Effect of image bit depth on target acquisition modeling
NASA Astrophysics Data System (ADS)
Teaney, Brian P.; Reynolds, Joseph P.
2008-04-01
The impact of bit depth on human in the loop recognition and identification performance is of particular importance when considering trade-offs between resolution and band-width of sensor systems. This paper presents the results from two perception studies designed to measure the effects of quantization and finite bit depth on target acquisition performance. The results in this paper allow for the inclusion of limited bit depth and quantization as an additional noise term in NVESD sensor performance models.
Validation of the Coronal Thick Target Source Model
NASA Astrophysics Data System (ADS)
Fleishman, Gregory D.; Xu, Yan; Nita, Gelu N.; Gary, Dale E.
2016-01-01
We present detailed 3D modeling of a dense, coronal thick-target X-ray flare using the GX Simulator tool, photospheric magnetic measurements, and microwave imaging and spectroscopy data. The developed model offers a remarkable agreement between the synthesized and observed spectra and images in both X-ray and microwave domains, which validates the entire model. The flaring loop parameters are chosen to reproduce the emission measure, temperature, and the nonthermal electron distribution at low energies derived from the X-ray spectral fit, while the remaining parameters, unconstrained by the X-ray data, are selected such as to match the microwave images and total power spectra. The modeling suggests that the accelerated electrons are trapped in the coronal part of the flaring loop, but away from where the magnetic field is minimal, and, thus, demonstrates that the data are clearly inconsistent with electron magnetic trapping in the weak diffusion regime mediated by the Coulomb collisions. Thus, the modeling supports the interpretation of the coronal thick-target sources as sites of electron acceleration in flares and supplies us with a realistic 3D model with physical parameters of the acceleration region and flaring loop.
Helicity-dependent generalized parton distributions and composite constituent quarks
Scopetta, Sergio; Vento, Vicente
2005-01-01
An approach, recently proposed to calculate the nucleon generalized parton distributions (GPDs) in a constituent quark model (CQM) scenario, in which the constituent quarks are taken as complex systems, is used to obtain helicity-dependent GPDs. They are obtained from the wave functions of the nonrelativistic CQM of Isgur and Karl, convoluted with the helicity-dependent GPDs of the constituent quarks themselves. The latter are modeled by using the polarized structure functions of the constituent quark, the double distribution representation of GPDs, and a phenomenological constituent quark form factor. The present approach permits us to access a kinematical range corresponding to both the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi and the Efremov-Radyushkin-Brodsky-Lepage regions, for small values of the momentum transfer and of the skewedness parameter. In this kinematical region, the present calculation represents a prerequisite for the evaluation of cross sections relevant to deeply virtual Compton scattering. In particular, we have calculated the leading twist helicity-dependent GPD H-tilde and, from our expressions, its general relations with the nonrelativistic definition of the axial form factor and with the leading twist polarized quark density are consistently recovered.
NASA Astrophysics Data System (ADS)
Karyan, Gevorg
2015-01-01
HERMES experiment at DESY in Hamburg collected a wealth of semi-inclusive deep-inelastic scattering data using the 27.6 GeV lepton beam and pure gaseous, unpolarised hydrogen and deuterium targets. These data can be used in studies of the transverse-momentum dependent effects and can provide a check of existing models for transverse-momentum dependent parton distribution and fragmentation functions.
Jimenez-Delgado, P.; Reya, E.
2009-12-01
Based on our recent next-to-next-to-leading order (NNLO) dynamical parton distributions as obtained in the 'fixed flavor number scheme', we generate radiatively parton distributions in the 'variable flavor number scheme' where the heavy-quark flavors (c,b,t) also become massless partons within the nucleon. Only within this latter factorization scheme are NNLO calculations feasible at present, since the required partonic subprocesses are only available in the approximation of massless initial-state partons. The NNLO predictions for gauge boson production are typically larger (by more than 1{sigma}) than the next-to-leading order (NLO) ones, and rates at LHC energies can be predicted with an accuracy of about 5%, whereas at Tevatron they are more than 2{sigma} above the NLO ones. The NNLO predictions for standard model Higgs-boson production via the dominant gluon fusion process have a total (parton distribution function and scale) uncertainty of about 10% at LHC which almost doubles at the lower Tevatron energies; they are typically about 20% larger than the ones at NLO but the total uncertainty bands overlap.
Model-based HSF using by target point control function
NASA Astrophysics Data System (ADS)
Kim, Seongjin; Do, Munhoe; An, Yongbae; Choi, Jaeseung; Yang, Hyunjo; Yim, Donggyu
2015-03-01
As the technology node shrinks, ArF Immersion reaches the limitation of wafer patterning, furthermore weak point during the mask processing is generated easily. In order to make strong patterning result, the design house conducts lithography rule checking (LRC). Despite LRC processing, we found the weak point at the verification stage of optical proximity correction (OPC). It is called the hot spot point (HSP). In order to fix the HSP, many studies have been performed. One of the most general hot spot fixing (HSF) methods is that the modification bias which consists of "Line-Resizing" and "Space-Resizing". In addition to the general rule biasing method, resolution enhancement techniques (RET) which includes the inverse lithography technology (ILT) and model based assist feature (MBAF) have been adapted to remove the hot spot and to maximize the process window. If HSP is found during OPC verification stage, various HSF methods can be applied. However, HSF process added on regular OPC procedure makes OPC turn-around time (TAT) increased. In this paper, we introduce a new HSF method that is able to make OPC TAT shorter than the common HSF method. The new HSF method consists of two concepts. The first one is that OPC target point is controlled to fix HSP. Here, the target point should be moved to optimum position at where the edge placement error (EPE) can be 0 at critical points. Many parameters such as a model accuracy or an OPC recipe become the cause of larger EPE. The second one includes controlling of model offset error through target point adjustment. Figure 1 shows the case EPE is not 0. It means that the simulation contour was not targeted well after OPC process. On the other hand, Figure 2 shows the target point is moved -2.5nm by using target point control function. As a result, simulation contour is matched to the original layout. This function can be powerfully adapted to OPC procedure of memory and logic devices.
Collective flow in event-by-event partonic transport plus hydrodynamics hybrid approach
NASA Astrophysics Data System (ADS)
Bhalerao, Rajeev S.; Jaiswal, Amaresh; Pal, Subrata
2015-07-01
Complete evolution of the strongly interacting matter formed in ultrarelativistic heavy-ion collisions is studied within a coupled Boltzmann and relativistic viscous hydrodynamics approach. For the initial nonequilibrium evolution phase, we employ a multiphase transport (AMPT) model that explicitly includes event-by-event fluctuations in the number and positions of the participating nucleons as well as of the produced partons with subsequent parton transport. The ensuing near-equilibrium evolution of quark-gluon and hadronic matter is modeled within the (2 +1 ) -dimensional relativistic viscous hydrodynamics. We probe the role of parton dynamics in generating and maintaining the spatial anisotropy in the preequilibrium phase. Substantial spatial eccentricities ɛn are found to be generated in the event-by-event fluctuations in parton production from initial nucleon-nucleon collisions. For ultracentral heavy-ion collisions, the model is able to explain qualitatively the unexpected hierarchy of the harmonic flow coefficients vn(pT) (n =2 -6 ) observed at energies currently available at the CERN Large Hadron Collider (LHC). We find that the results for vn(pT) are rather insensitive to the variation (within a range) of the time of switchover from AMPT parton transport to hydrodynamic evolution. The usual Grad and the recently proposed Chapman-Enskog-like (nonequilibrium) single-particle distribution functions are found to give very similar results for vn(n =2 -4 ) . The model describes well both the BNL Relativistic Heavy Ion Collider and LHC data for vn(pT) at various centralities, with a constant shear viscosity to entropy density ratio of 0.08 and 0.12, respectively. The event-by-event distributions of v2 ,3 are in good agreement with the LHC data for midcentral collisions. The linear response relation vn=knɛn is found to be true for n =2 ,3 , except at large values of ɛn, where a larger value of kn is required, suggesting a small admixture of positive nonlinear
How to impose initial conditions for QCD evolution of double parton distributions?
NASA Astrophysics Data System (ADS)
Golec-Biernat, Krzysztof; Lewandowska, Emilia
2014-07-01
Double parton distribution functions are used in the QCD description of double parton scattering. The double parton distributions evolve with hard scales through QCD evolution equations which obey nontrivial momentum and valence quark number sum rules. We describe an attempt to construct initial conditions for the evolution equations which exactly fulfill these sum rules and discuss its shortcomings. We also discuss the factorization of the double parton distributions into a product of two single parton distribution functions at small values of the parton momentum fractions.
From C to Parton Sea: How Supercomputing Reveals Nucleon Structure
NASA Astrophysics Data System (ADS)
Lin, Huey-Wen
2016-03-01
Studying the structure of nucleons is not only important to understanding the strong interactions of quarks and gluons, but also to improving the precision of new-physics searches. Since a broad class of experiments, including the LHC and dark-matter detection, require interactions with nucleons, the mission to probe femtoscale physics is also essential for disentangling Standard-Model contributions from potential new physics. These SM backgrounds require parton distribution functions (PDFs) as inputs. However, after decades of experiments and theoretical efforts, there still remain many unknowns, especially in the sea flavor structure and transversely polarized structure. In a discrete spacetime, we can make a direct numerical calculation of the implications of QCD using sufficiently large supercomputing resources. A nonperturbative approach from first principles, lattice QCD, provides hope to expand our understanding of nucleon structure, especially in regions that are difficult to observe in experiments. In this work, we present a first direct calculation of the Bjorken-x dependence of the PDFs using Large-Momentum Effective Theory (LaMET) and comment on the surprising result revealed for the nucleon sea-flavor asymmetry. The work of HWL is supported in part by the M. Hildred Blewett Fellowship of the American Physical Society, www.aps.org.
Medium Modifications of Hadron Properties and Partonic Processes
Brooks, W. K.; Strauch, S.; Tsushima, K.
2011-06-01
Chiral symmetry is one of the most fundamental symmetries in QCD. It is closely connected to hadron properties in the nuclear medium via the reduction of the quark condensate
Modeling the target acquisition performance of active imaging systems.
Espinola, Richard L; Jacobs, Eddie L; Halford, Carl E; Vollmerhausen, Richard; Tofsted, David H
2007-04-01
Recent development of active imaging system technology in the defense and security community have driven the need for a theoretical understanding of its operation and performance in military applications such as target acquisition. In this paper, the modeling of active imaging systems, developed at the U.S. Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate, is presented with particular emphasis on the impact of coherent effects such as speckle and atmospheric scintillation. Experimental results from human perception tests are in good agreement with the model results, validating the modeling of coherent effects as additional noise sources. Example trade studies on the design of a conceptual active imaging system to mitigate deleterious coherent effects are shown. PMID:19532626
Modeling the target acquisition performance of active imaging systems
NASA Astrophysics Data System (ADS)
Espinola, Richard L.; Jacobs, Eddie L.; Halford, Carl E.; Vollmerhausen, Richard; Tofsted, David H.
2007-04-01
Recent development of active imaging system technology in the defense and security community have driven the need for a theoretical understanding of its operation and performance in military applications such as target acquisition. In this paper, the modeling of active imaging systems, developed at the U.S. Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate, is presented with particular emphasis on the impact of coherent effects such as speckle and atmospheric scintillation. Experimental results from human perception tests are in good agreement with the model results, validating the modeling of coherent effects as additional noise sources. Example trade studies on the design of a conceptual active imaging system to mitigate deleterious coherent effects are shown.
Multitarget sensor resolution model for arbitrary target numbers
NASA Astrophysics Data System (ADS)
Svensson, Daniel; Ulmke, Martin; Danielsson, Lars
2010-04-01
In many surveillance problems the observed objects are so closely spaced that they cannot always be resolved by the sensor(s). Typical examples for partially unresolved measurements are the surveillance of aircraft in formation, and convoy tracking for ground surveillance. Ignoring the limited sensor resolution in a tracking system may lead to degraded tracking performance, in particular unwanted track-losses. In this paper we extend the resolution model by Koch and van Keuk, given for two partially unresolved objects, to the case of arbitrary object numbers. We also derive the effects of the resolution model to the multi-target likelihood function and the possible data associations. Further, it is shown how the model can be integrated into the Joint Probabilistic Data Association Filter (JPDAF).
Optical model analyses of heavy ion fragmentation in hydrogen targets
NASA Technical Reports Server (NTRS)
Townsend, Lawrence W.
1994-01-01
Quantum-mechanical optical-model methods for calculating cross sections for the fragmentation of high-energy heavy ions by hydrogen targets are presented. The cross sections are calculated with a knockout-ablation collision formalism which has no arbitrary fitting parameters. Predictions of elemental production cross sections from the fragmentation of 1.2A Ge(V(La-139) nuclei and of isotope production cross sections from the fragmentation of 400A MeV(S-32) nuclei are in good agreement with recently reported experimental measurements.
Target Cueing Provides Support for Target- and Resource-Based Models of the Attentional Blink
Pincham, Hannah L.; Szűcs, Dénes
2012-01-01
The attentional blink (AB) describes a time-based deficit in processing the second of two masked targets. The AB is attenuated if successive targets appear between the first and final target, or if a cueing target is positioned before the final target. Using various speeds of stimulus presentation, the current study employed successive targets and cueing targets to confirm and extend an understanding of target-target cueing in the AB. In Experiment 1, three targets were presented sequentially at rates of 30 msec/item or 90 msec/item. Successive targets presented at 90 msec improved performance compared with non-successive targets. However, accuracy was equivalently high for successive and non-successive targets presented at 30 msec/item, suggesting that–regardless of whether they occurred consecutively–those items fell within the temporally defined attentional window initiated by the first target. Using four different presentation speeds, Experiment 2 confirmed the time-based definition of the AB and the success of target-cueing at 30 msec/item. This experiment additionally revealed that cueing was most effective when resources were not devoted to the cue, thereby implicating capacity limitations in the AB. Across both experiments, a novel order-error measure suggested that errors tend to decrease with an increasing duration between the targets, but also revealed that certain stimulus conditions result in stable order accuracy. Overall, the results are best encapsulated by target-based and resource-sharing theories of the AB, which collectively value the contributions of capacity limitations and optimizing transient attention in time. PMID:22629426
Systematic improvement of parton showers with effective theory
NASA Astrophysics Data System (ADS)
Baumgart, Matthew; Marcantonini, Claudio; Stewart, Iain W.
2011-02-01
We carry out a systematic classification and computation of next-to-leading order kinematic power corrections to the fully differential cross section in the parton shower. To do this we devise a map between ingredients in a parton shower and operators in a traditional effective field theory framework using a chain of soft-collinear effective theories. Our approach overcomes several difficulties including avoiding double counting and distinguishing approximations that are coordinate choices from true power corrections. Branching corrections can be classified as hard-scattering, that occur near the top of the shower, and jet-structure, that can occur at any point inside it. Hard-scattering corrections include matrix elements with additional hard partons, as well as power suppressed contributions to the branching for the leading jet. Jet-structure corrections require simultaneous consideration of potential 1→2 and 1→3 branchings. The interference structure induced by collinear terms with subleading powers remains localized in the shower.
Elasticity-based targeted growth models of morphogenesis.
Alford, Patrick W
2015-01-01
Embryonic tissue mechanics play an important role in regulating morphogenesis during organ formation, both in a bottom-up sense, where changes in gene expression drive mechanical shape changes, and in a top-down sense, where perturbations in tissue mechanics feed back to drive changes in gene expression. In growing tissues that can generate internal forces and have complex geometries, like those in the embryo, it can often be difficult to empirically determine the mechanical state of the tissue, let alone the relationships between gene expression and mechanical behavior. Mathematical models can be used to fill this gap. Here, we discuss elasticity-based models for growing tissues with a specific focus on targeted growth in embryonic tissues. PMID:25245704
Interference effect in elastic parton energy loss in a finitemedium
Wang, Xin-Nian
2005-04-18
Similar to the radiative parton energy loss due to gluonbremsstrahlung, elastic energy loss of a parton undergoing multiplescattering in a finite medium is demonstrated to be sensitive tointerference effect. The interference between amplitudes of elasticscattering via a gluon exchange and that of gluon radiation reduces theeffective elastic energy loss in a finite medium and gives rise to anon-trivial length dependence. The reduction is most significant for apropagation length L<4/\\pi T in a medium with a temperature T. Thoughthe finite size effect is not significant for the average partonpropagation in the most central heavy-ion collisions, it will affect thecentrality dependence of its effect on jet quenching.
Delineating the polarized and unpolarized partonic structure of the nucleon
Jimenez-Delgado, Pedro
2015-03-01
Our latest results on the extraction of parton distribution functions of the nucleon are reported. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are given, including a careful treatment of hadronic and nuclear corrections, as well as results on the impact of present and future data in our understanding of the spin of the nucleon.
Transverse Momentum Dependent (TMD) Parton Distribution Functions: Status and Prospects
NASA Astrophysics Data System (ADS)
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, I. I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F. A.; Cherednikov, I. O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Grados Luyando, J.; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J. P.; Lelek, A.; Lykasov, G.; Madrigal Martinez, J. D.; Mulders, P. J.; Nocera, E. R.; Petreska, E.; Pisano, C.; Plačakytė, R.; Radescu, V.; Radici, M.; Schnell, G.; Scimemi, I.; Signori, A.; Szymanowski, L.; Taheri Monfared, S.; Van der Veken, F. F.; van Haevermaet, H. J.; Van Mechelen, P.; Vladimirov, A. A.; Wallon, S.
We provide a concise overview on transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q_T spectra of Higgs and vector bosons for low q_T, and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present an application of a new tool, TMDlib, to parton density fits and parameterizations.
The role of the input scale in parton distribution analyses
Pedro Jimenez-Delgado
2012-08-01
A first systematic study of the effects of the choice of the input scale in global determinations of parton distributions and QCD parameters is presented. It is shown that, although in principle the results should not depend on these choices, in practice a relevant dependence develops as a consequence of what is called procedural bias. This uncertainty should be considered in addition to other theoretical and experimental errors, and a practical procedure for its estimation is proposed. Possible sources of mistakes in the determination of QCD parameter from parton distribution analysis are pointed out.
Nucleon generalized parton distributions from full lattice QCD
Haegler, Ph.; Musch, B.; Schroers, W.; Edwards, R. G.; Richards, D. G.; Engelhardt, M.; Fleming, G. T.; Orginos, K.; Renner, D. B.
2008-05-01
We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N{sub f}=2+1 lattice QCD using domain-wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm){sup 3}, for a lattice spacing of 0.124 fm. We use perturbative renormalization at one-loop level with an improvement based on the nonperturbative renormalization factor for the axial vector current, and only connected diagrams are included in the isosinglet channel.
Delineating the polarized and unpolarized partonic structure of the nucleon
Jimenez-Delgado, Pedro
2015-03-01
Reports on our latest extractions of parton distribution functions of the nucleon are given. First an overview of the recent JR14 upgrade of our unpolarized PDFs, including NNLO determinations of the strong coupling constant and a discussion of the role of the input scale in parton distribution analysis. In the second part of the talk recent results on the determination of spin-dependent PDFs from the JAM collaboration are reported, including a careful treatment of hadronic and nuclear corrections, as well as reports on the impact of present and future data in our understanding of the spin of the nucleon.
Quantum Statistical Parton Distributions and the Spin Crisis
NASA Astrophysics Data System (ADS)
Buccella, F.; Miele, G.; Tancredi, N.
1996-10-01
Quantum statistical distributions for partons provide a fair description of deep inelastic scattering data at Q2 = 3 and 10 (GeV/c)2. Study of the polarized structure functions seems to suggest an alternative possible solution of the spin crisis based on the Pauli principle. In this scheme, in fact, it becomes apparent that the defects of the Gottfried sum rule and Ellis-Jaffe sum rule for the proton are strongly connected. This possibility finds particular evidence from the phenomenological observation that the relation Δu = 2$tilde{F} + u - d - 1 seems to be satisfied well by parton distributions.
Transverse momentum dependent (TMD) parton distribution functions: Status and prospects*
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, Ian I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F. A.; Cherednikov, I. O.; Connor, P.; Echevarria, M. G.; et al
2015-01-01
In this study, we review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum qT spectra of Higgs and vector bosons for low qT, and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present the application of a new tool, TMDLIB, to parton density fits and parameterizations.
DISSECTING OCD CIRCUITS: FROM ANIMAL MODELS TO TARGETED TREATMENTS.
Ahmari, Susanne E; Dougherty, Darin D
2015-08-01
Obsessive-compulsive disorder (OCD) is a chronic, severe mental illness with up to 2-3% prevalence worldwide. In fact, OCD has been classified as one of the world's 10 leading causes of illness-related disability according to the World Health Organization, largely because of the chronic nature of disabling symptoms.([1]) Despite the severity and high prevalence of this chronic and disabling disorder, there is still relatively limited understanding of its pathophysiology. However, this is now rapidly changing due to development of powerful technologies that can be used to dissect the neural circuits underlying pathologic behaviors. In this article, we describe recent technical advances that have allowed neuroscientists to start identifying the circuits underlying complex repetitive behaviors using animal model systems. In addition, we review current surgical and stimulation-based treatments for OCD that target circuit dysfunction. Finally, we discuss how findings from animal models may be applied in the clinical arena to help inform and refine targeted brain stimulation-based treatment approaches. PMID:25952989
Dissecting OCD Circuits: From Animal Models to Targeted Treatments
Ahmari, Susanne E.; Dougherty, Darin D.
2015-01-01
Obsessive Compulsive Disorder (OCD) is a chronic, severe mental illness with up to 2–3% prevalence worldwide, which has been classified as one of the world’s 10 leading causes of illness-related disability according to the World Health Organization, largely because of the chronic nature of disabling symptoms 1. Despite the severity and high prevalence of this chronic and disabling disorder, there is still relatively limited understanding of its pathophysiology. However, this is now rapidly changing due to development of powerful technologies that can be used to dissect the neural circuits underlying pathologic behaviors. In this article, we describe recent technical advances that have allowed neuroscientists to start identifying the circuits underlying complex repetitive behaviors using animal model systems. In addition, we review current surgical and stimulation-based treatments for OCD that target circuit dysfunction. Finally, we discuss how findings from animal models may be applied in the clinical arena to help inform and refine targeted brain stimulation-based treatment approaches. PMID:25952989
Target space pseudoduality in supersymmetric sigma models on symmetric spaces
NASA Astrophysics Data System (ADS)
Sarisaman, Mustafa
We discuss the target space pseudoduality in supersymmetric sigma models on symmetric spaces. We first consider the case where sigma models based on real compact connected Lie groups of the same dimensionality and give examples using three dimensional models on target spaces. We show explicit construction of nonlocal conserved currents on the pseudodual manifold. We then switch the Lie group valued pseudoduality equations to Lie algebra valued ones, which leads to an infinite number of pseudoduality equations. We obtain an infinite number of conserved currents on the tangent bundle of the pseudo-dual manifold. Since pseudoduality imposes the condition that sigma models pseudodual to each other are based on symmetric spaces with opposite curvatures (i.e. dual symmetric spaces), we investigate pseudoduality transformation on the symmetric space sigma models in the third chapter. We see that there can be mixing of decomposed spaces with each other, which leads to mixings of the following expressions. We obtain the pseudodual conserved currents which are viewed as the orthonormal frame on the pullback bundle of the tangent space of G˜ which is the Lie group on which the pseudodual model based. Hence we obtain the mixing forms of curvature relations and one loop renormalization group beta function by means of these currents. In chapter four, we generalize the classical construction of pseudoduality transformation to supersymmetric case. We perform this both by component expansion method on manifold M and by orthonormal coframe method on manifold SO( M). The component method produces the result that pseudoduality transformation is not invertible at all points and occurs from all points on one manifold to only one point where riemann normal coordinates valid on the second manifold. Torsion of the sigma model on M must vanish while it is nonvanishing on M˜, and curvatures of the manifolds must be constant and the same because of anticommuting grassmann numbers. We obtain
Target detection in hyperspectral imagery using forward modeling and in-scene information
NASA Astrophysics Data System (ADS)
Axelsson, Maria; Friman, Ola; Haavardsholm, Trym Vegard; Renhorn, Ingmar
2016-09-01
This work addresses the problem of detecting and classifying materials and targets in hyperspectral images based on their reflectance spectrum. Accurate target detection in hyperspectral imagery requires a radiative transfer model that maps between the spectral reflectance domain and the measured radiance domain. Such a model can be employed in two ways for detection - using atmospheric compensation, where the measured hyperspectral radiance image is converted to a reflectance image, and using forward modeling, where the target reflectance spectrum is converted to an at-sensor target radiance spectrum. This work presents a forward modeling detection method that utilizes in-scene information to estimate the parameters in the radiative transfer model. Uncertainty in the radiative transfer model and variability of the target spectra are captured using a constrained subspace model for the target. Target detection using library spectra and target rediscovery are evaluated in hyperspectral images of a complex urban scene.
PARTON SATURATION, PRODUCTION, AND EQUILIBRATION IN HIGH ENERGY NUCLEAR COLLISIONS
VENUGOPALAN,R.
1999-03-20
Deeply inelastic scattering of electrons off nuclei can determine whether parton distributions saturate at HERA energies. If so, this phenomenon will also tell us a great deal about how particles are produced, and whether they equilibrate, in high energy nuclear collisions.
Global parton distributions for the LHC Run II
NASA Astrophysics Data System (ADS)
Ball, R. D.
2016-07-01
We review the next generation global PDF sets: NNPDF3.0, MMHT14 and CT14. We describe the global datasets, particularly the new data from LHC Run I, the developments in QCD theory and PDF methodology, recent improvements in their combination and delivery, and future prospects for parton determination at Run II.
Parton Distributions in the Nucleon and the Pauli Principle
NASA Astrophysics Data System (ADS)
Buccella, Franco; Soffer, Jacques
The Pauli principle is used, together with some deep inelastic scattering data, to guide us in making reasonable assumptions for various polarized parton distributions in terms of unpolarized distributions. We relate the violation of the Gottfried and Ellis-Jaffe sum rules and we anticipate a substantial violation of the Bjorken sum rule.
New Results in the Quantum Statistical Approach to Parton Distributions
NASA Astrophysics Data System (ADS)
Soffer, Jacques; Bourrely, Claude; Buccella, Franco
2015-02-01
We will describe the quantum statistical approach to parton distributions allowing to obtain simultaneously the unpolarized distributions and the helicity distributions. We will present some recent results, in particular related to the nucleon spin structure in QCD. Future measurements are challenging to check the validity of this novel physical framework.
Informing Pedagogy Through the Brain-Targeted Teaching Model
Hardiman, Mariale
2012-01-01
Improving teaching to foster creative thinking and problem-solving for students of all ages will require two essential changes in current educational practice. First, to allow more time for deeper engagement with material, it is critical to reduce the vast number of topics often required in many courses. Second, and perhaps more challenging, is the alignment of pedagogy with recent research on cognition and learning. With a growing focus on the use of research to inform teaching practices, educators need a pedagogical framework that helps them interpret and apply research findings. This article describes the Brain-Targeted Teaching Model, a scheme that relates six distinct aspects of instruction to research from the neuro- and cognitive sciences. PMID:23653775
Matching next-to-leading order predictions to parton showers in supersymmetric QCD
Degrande, Céline; Fuks, Benjamin; Hirschi, Valentin; Proudom, Josselin; Shao, Hua-Sheng
2016-02-03
We present a fully automated framework based on the FeynRules and MadGraph5_aMC@NLO programs that allows for accurate simulations of supersymmetric QCD processes at the LHC. Starting directly from a model Lagrangian that features squark and gluino interactions, event generation is achieved at the next-to-leading order in QCD, matching short-distance events to parton showers and including the subsequent decay of the produced supersymmetric particles. As an application, we study the impact of higher-order corrections in gluino pair-production in a simplified benchmark scenario inspired by current gluino LHC searches.
Non-Universality of Transverse Momentum Dependent Parton Distributions at Small-x
Xiao, Bowen; Yuan, Feng
2010-02-22
We study the universality of the transverse momentum dependent parton distributions at small-x, by comparing the initial/final state interaction effects in dijet-correlation in pA collisions with that in deep inelastic lepton nucleus scattering. We demonstrate the non-universality by an explicit calculation in a particular model where the multiple gauge boson exchange contributions are summed up to all orders. We furthercomment on the implications of our results on the theoretical interpretation of di-hadron correlation in dA collisions in terms of the saturation phenomena in deep inelastic lepton nucleus scattering.
VBFNLO: A parton level Monte Carlo for processes with electroweak bosons
NASA Astrophysics Data System (ADS)
Arnold, K.; Bähr, M.; Bozzi, G.; Campanario, F.; Englert, C.; Figy, T.; Greiner, N.; Hackstein, C.; Hankele, V.; Jäger, B.; Klämke, G.; Kubocz, M.; Oleari, C.; Plätzer, S.; Prestel, S.; Worek, M.; Zeppenfeld, D.
2009-09-01
VBFNLO is a fully flexible parton level Monte Carlo program for the simulation of vector boson fusion, double and triple vector boson production in hadronic collisions at next-to-leading order in the strong coupling constant. VBFNLO includes Higgs and vector boson decays with full spin correlations and all off-shell effects. In addition, VBFNLO implements CP-even and CP-odd Higgs boson via gluon fusion, associated with two jets, at the leading-order one-loop level with the full top- and bottom-quark mass dependence in a generic two-Higgs-doublet model. A variety of effects arising from beyond the Standard Model physics are implemented for selected processes. This includes anomalous couplings of Higgs and vector bosons and a Warped Higgsless extra dimension model. The program offers the possibility to generate Les Houches Accord event files for all processes available at leading order. Program summaryProgram title:VBFNLO Catalogue identifier: AEDO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEDO_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPL version 2 No. of lines in distributed program, including test data, etc.: 339 218 No. of bytes in distributed program, including test data, etc.: 2 620 847 Distribution format: tar.gz Programming language: Fortran, parts in C++ Computer: All Operating system: Linux, should also work on other systems Classification: 11.1, 11.2 External routines: Optionally Les Houches Accord PDF Interface library and the GNU Scientific library Nature of problem: To resolve the large scale dependence inherent in leading order calculations and to quantify the cross section error induced by uncertainties in the determination of parton distribution functions, it is necessary to include NLO corrections. Moreover, whenever stringent cuts are required on decay products and/or identified jets the question arises whether the scale dependence and a k-factor, defined
Flexible parametrization of generalized parton distributions: The chiral-odd sector
NASA Astrophysics Data System (ADS)
Goldstein, Gary R.; Hernandez, J. Osvaldo Gonzalez; Liuti, Simonetta
2015-06-01
We present a physically motivated parametrization of the chiral-odd generalized parton distributions. The parametrization is an extension of our previous one in the chiral-even sector which was based on the Reggeized diquark model. While for chiral-even generalized distributions a quantitative fit with uncertainty estimation can be performed using deep inelastic scattering data, nucleon electromagnetic, axial and pseudoscalar form factors measurements, and all available deeply virtual Compton scattering data, the chiral-odd sector is far less constrained. While awaiting the analysis of measurements on pseudoscalar mesons exclusive electroproduction which are key for the extraction of chiral-odd GPDs, we worked out a connection between the chiral-even and chiral-odd reduced helicity amplitudes using parity transformations. The connection works for quark-parton models including both scalar and axial vector diquark models, and spectator models in general. This relation allows us to estimate the size of the various chiral-odd contributions and it opens the way for future quantitative fits.
Airborne electromagnetic modelling options and their consequences in target definition
NASA Astrophysics Data System (ADS)
Ley-Cooper, Alan Yusen; Viezzoli, Andrea; Guillemoteau, Julien; Vignoli, Giulio; Macnae, James; Cox, Leif; Munday, Tim
2015-10-01
Given the range of geological conditions under which airborne EM surveys are conducted, there is an expectation that the 2D and 3D methods used to extract models that are geologically meaningful would be favoured over 1D inversion and transforms. We do after all deal with an Earth that constantly undergoes, faulting, intrusions, and erosive processes that yield a subsurface morphology, which is, for most parts, dissimilar to a horizontal layered earth. We analyse data from a survey collected in the Musgrave province, South Australia. It is of particular interest since it has been used for mineral prospecting and for a regional hydro-geological assessment. The survey comprises abrupt lateral variations, more-subtle lateral continuous sedimentary sequences and filled palaeovalleys. As consequence, we deal with several geophysical targets of contrasting conductivities, varying geometries and at different depths. We invert the observations by using several algorithms characterised by the different dimensionality of the forward operator. Inversion of airborne EM data is known to be an ill-posed problem. We can generate a variety of models that numerically adequately fit the measured data, which makes the solution non-unique. The application of different deterministic inversion codes or transforms to the same dataset can give dissimilar results, as shown in this paper. This ambiguity suggests the choice of processes and algorithms used to interpret AEM data cannot be resolved as a matter of personal choice and preference. The degree to which models generated by a 1D algorithm replicate/or not measured data, can be an indicator of the data's dimensionality, which perse does not imply that data that can be fitted with a 1D model cannot be multidimensional. On the other hand, it is crucial that codes that can generate 2D and 3D models do reproduce the measured data in order for them to be considered as a plausible solution. In the absence of ancillary information, it could
Cellular communication and “non-targeted effects”: Modelling approaches
NASA Astrophysics Data System (ADS)
Ballarini, Francesca; Facoetti, Angelica; Mariotti, Luca; Nano, Rosanna; Ottolenghi, Andrea
2009-10-01
During the last decade, a large number of experimental studies on the so-called "non-targeted effects", in particular bystander effects, outlined that cellular communication plays a significant role in the pathways leading to radiobiological damage. Although it is known that two main types of cellular communication (i.e. via gap junctions and/or molecular messengers diffusing in the extra-cellular environment, such as cytokines, NO etc.) play a major role, it is of utmost importance to better understand the underlying mechanisms, and how such mechanisms can be modulated by ionizing radiation. Though the "final" goal is of course to elucidate the in vivo scenario, in the meanwhile also in vitro studies can provide useful insights. In the present paper we will discuss key issues on the mechanisms underlying non-targeted effects and cell communication, for which theoretical models and simulation codes can be of great help. In this framework, we will present in detail three literature models, as well as an approach under development at the University of Pavia. More specifically, we will first focus on a version of the "State-Vector Model" including bystander-induced apoptosis of initiated cells, which was successfully fitted to in vitro data on neoplastic transformation supporting the hypothesis of a protective bystander effect mediated by apoptosis. The second analyzed model, focusing on the kinetics of bystander effects in 3D tissues, was successfully fitted to data on bystander damage in an artificial 3D skin system, indicating a signal range of the order of 0.7-1 mm. A third model for bystander effect, taking into account of spatial location, cell killing and repopulation, showed dose-response curves increasing approximately linearly at low dose rates but quickly flattening out for higher dose rates, also predicting an effect augmentation following dose fractionation. Concerning the Pavia approach, which can model the release, diffusion and depletion/degradation of
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
Frankfurt, L.; Hyde, C. E.; Strikman, M.; Weiss, C.
2007-03-01
We study rapidity gap survival (RGS) in the production of high-mass systems (H=dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp{yields}p+(gap)+H+(gap)+p. Our approach is based on the idea that hard and soft interactions are approximately independent because they proceed over widely different time and distance scales. We implement this idea in a partonic description of proton structure, which allows for a model-independent treatment of the interplay of hard and soft interactions. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons, whose amplitude is calculable in terms of the gluon generalized parton distribution (GPD), measured in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate neglecting correlations between hard and soft interactions (independent interaction approximation). We obtain an analytic expression for the RGS probability in terms of the phenomenological pp elastic scattering amplitude, without reference to the eikonal approximation. Contributions from inelastic intermediate states are suppressed. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons ('diffraction pattern'). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the
Modeling to Support the Development of Habitat Targets for Piping Plovers on the Missouri River
Buenau, Kate E.
2015-05-05
Report on modeling and analyses done in support of developing quantative sandbar habitat targets for piping plovers, including assessment of reference, historical, dams present but not operated, and habitat construction calibrated to meet population viability targets.
Glueck, M.; Reya, E.; Pisano, C.
2008-04-01
Recent measurements for F{sub 2}(x,Q{sup 2}) have been analyzed in terms of the 'dynamical' and 'standard' parton model approach at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) of perturbative QCD. Having fixed the relevant NLO and NNLO parton distributions, we present the implications and predictions for the longitudinal structure function F{sub L}(x,Q{sup 2}). It is shown that the previously noted extreme perturbative NNLO/NLO instability of F{sub L}(x,Q{sup 2}) is an artifact of the commonly utilized 'standard' gluon distributions. In particular it is demonstrated that using the appropriate--dynamically generated--parton distributions at NLO and NNLO, F{sub L}(x,Q{sup 2}) turns out to be perturbatively rather stable already for Q{sup 2}{>=}O(2-3 GeV{sup 2})
Technology Transfer Automated Retrieval System (TEKTRAN)
Cost-effective nonpoint source phosphorus (P) control should target the land areas at greatest risk for P loss. We combined mass-balance modeling and geographic analysis to identify and map high-risk areas for P export by integrating long-term P input/output accounting with spatially variable physi...
Transverse momentum dependent (TMD) parton distribution functions: Status and prospects*
Angeles-Martinez, R.; Bacchetta, A.; Balitsky, Ian I.; Boer, D.; Boglione, M.; Boussarie, R.; Ceccopieri, F. A.; Cherednikov, I. O.; Connor, P.; Echevarria, M. G.; Ferrera, G.; Grados Luyando, J.; Hautmann, F.; Jung, H.; Kasemets, T.; Kutak, K.; Lansberg, J. P.; Lykasov, G.; Madrigal Martinez, J. D.; Mulders, P. J.; Nocera, E. R.; Petreska, E.; Pisano, C.; Placakyte, R.; Radescu, V.; Radici, M.; Schnell, G.; Signori, A.; Szymanowski, L.; Taheri Monfared, S.; Van der Veken, F. F.; van Haevermaet, H. J.; Van Mechelen, P.; Vladimirov, A. A.; Wallon, S.
2015-01-01
In this study, we review transverse momentum dependent (TMD) parton distribution functions, their application to topical issues in high-energy physics phenomenology, and their theoretical connections with QCD resummation, evolution and factorization theorems. We illustrate the use of TMDs via examples of multi-scale problems in hadronic collisions. These include transverse momentum q_{T} spectra of Higgs and vector bosons for low q_{T}, and azimuthal correlations in the production of multiple jets associated with heavy bosons at large jet masses. We discuss computational tools for TMDs, and present the application of a new tool, TMD_{LIB}, to parton density fits and parameterizations.
Nuclear Parton Distributions with the LHeC
NASA Astrophysics Data System (ADS)
Klein, Max
2016-03-01
Nuclear parton distributions are far from being known today because of an infant experimental base. Based on design studies of the LHeC and using new simulations, of the inclusive neutral and charged current cross section measurements and of the strange, charm and beauty densities in nuclei, it is demonstrated how that energy frontier electron-ion collider would unfold the complete set of nuclear PDFs in a hugely extended kinematic range of deep inelastic scattering, extending in Bjorken x down to values near to 10-6 in the perturbative domain. Together with a very precise and complete set of proton PDFs, the LHeC nPDFs will thoroughly change the theoretical understanding of parton dynamics and structure inside hadrons.
Ground target infrared signature model validation for real-time hardware-in-the-loop simulations
NASA Astrophysics Data System (ADS)
Sanders, Jeffrey S.; Rodgers, Jeremy B.; Siddique, Ahmed A.
1998-07-01
Techniques and tools for validation of real-time infrared target signature models are presented. The model validation techniques presented in this paper were developed for hardware-in-the-loop (HWIL) simulations at the U.S. Army Missile Command's Research, Development, and Engineering Center. Real-time target model validation is a required deliverable to the customer of a HWIL simulation facility and is a critical part of ensuring the fidelity of a HWIL simulation. There are two levels of real-time target model validation. The first level is comparison of the target model to some baseline or measured data which answers the question 'are the simulation inputs correct?' The second level of validation is a simulation validation which answers the question 'for a given target model input are the simulation hardware and software generating the correct output?' This paper deals primarily with the first level of target model validation.
Deep Exclusive Scattering and Generalized Parton Distributions : Experimental Review
Franck Sabatie
2004-10-01
Since the Generalized Parton Distribution theoretical framework was introduced in the late 90's, a few published and numerous preliminary results from Deep Exclusive Scattering (DES) have been extracted from non-dedicated experiments at HERA and Jefferson Lab. We review most of these results, comment on the ongoing dedicated research in this topic and conclude with the expectations from the next generation of experiments in the near future.
Moments of nucleon spin-dependent generalized parton distributions
Wolfram Schroers; Richard Brower; Patrick Dreher; Robert Edwards; George Fleming; P. Hagler; Urs Heller; Thomas Lippert; John Negele; Andrew Pochinsky; Dru Renner; David Richards; Klaus Schilling
2004-03-01
We present a lattice measurement of the first two moments of the spin-dependent GPD H-tilde(x,xi,t). From these we obtain the axial coupling constant and the second moment of the spin-dependent forward parton distribution. The measurements are done in full QCD using Wilson fermions. In addition, we also present results from a first exploratory study of full QCD using Asqtad sea and domain-wall valence fermions.
Deeply Pseudoscalar Meson Electroproduction with CLAS and Generalized Parton Distributions
Guidal, Michel; Kubarovsky, Valery P.
2015-06-01
We discuss the recent data of exclusive $\\pi^0$ (and $\\pi^+$) electroproduction on the proton obtained by the CLAS collaboration at Jefferson Lab. It is observed that the cross sections, which have been decomposed in $\\sigma_T+\\epsilon\\sigma_L$, $\\sigma_{TT}$ and $\\sigma_{LT}$ structure functions, are dominated by transverse amplitude contributions. The data can be interpreted in the Generalized Parton Distribution formalism provided that one includes helicity-flip transversity GPDs.
Generalized parton distributions in a light-front nonperturbative approach
NASA Astrophysics Data System (ADS)
Chakrabarti, D.; Zhao, X.; Honkanen, H.; Manohar, R.; Maris, P.; Vary, J. P.
2014-06-01
Basis light-front quantization (BLFQ) has recently been developed as a promising nonperturbative technique. Using BLFQ, we investigate the generalized parton distributions (GPDs) in a nonperturbative framework for a dressed electron in QED. We evaluate light-front wave functions and carry out overlap calculations to obtain GPDs. We also perform perturbative calculations in the corresponding basis spaces to demonstrate that they compare reasonably with the BLFQ results.
Fermi-Dirac statistics plus liquid description of quark partons
NASA Astrophysics Data System (ADS)
Buccella, F.; Miele, G.; Migliore, G.; Tibullo, V.
1995-12-01
A previous approach with Fermi-Dirac distributions for fermion partons is here improved to comply with the expected low x behaviour of structure functions. We are so able to get a fair description of the unpolarized and polarized structure functions of the nucleons as well as of neutrino data. We cannot reach definite conclusions, but confirm our suspicion of a relationship between the defects in Gottfried and spin sum rules.
W± bosons production in the quantum statistical parton distributions approach
NASA Astrophysics Data System (ADS)
Bourrely, Claude; Buccella, Franco; Soffer, Jacques
2013-10-01
We consider W± gauge bosons production in connection with recent results from BNL-RHIC and FNAL-Tevatron and interesting predictions from the statistical parton distributions. They concern relevant aspects of the structure of the nucleon sea and the high-x region of the valence quark distributions. We also give predictions in view of future proton-neutron collisions experiments at BNL-RHIC.
Multiple parton interactions in hadron collisions and diffraction
Lipari, Paolo; Lusignoli, Maurizio
2009-10-01
Hadrons are composite objects made of quarks and gluons, and during a collision one can have several elementary interactions between the constituents. These elementary interactions, using an appropriate theoretical framework, can be related to the total and elastic cross sections. At high c.m. energy it also becomes possible to identify experimentally a high p{sub perpendicular} subset of the parton interactions and to study their multiplicity distribution. Predictions of the multiple interaction rates are difficult because in principle one needs to have a knowledge of the correlated parton distribution functions that describe the probability to find simultaneously different partons in different elements of phase space. In this work we address this question and suggest a method to describe effectively the fluctuations in the instantaneous configuration of a colliding hadron. This problem is intimately related to the origin of the inelastic diffractive processes. We present a new method to include the diffractive cross section in an eikonal formalism that is equivalent to a multichannel eikonal. We compare with data and present an extrapolation to higher energy.
High range resolution radar target identification using the Prony model and hidden Markov models
NASA Astrophysics Data System (ADS)
Dewitt, Mark R.
1992-12-01
Fully polarized Xpatch signatures are transformed to two left circularly polarized signals. These two signals are then filtered by a linear FM pulse compression ('chirp') transfer function, corrupted by AWGN, and filtered by a filter matched to the 'chirp' transfer function. The bandwidth of the 'chirp' radar is about 750 MHz. Range profile feature extraction is performed using the TLS Prony Model parameter estimation technique developed at Ohio State University. Using the Prony Model, each scattering center is described by a polarization ellipse, relative energy, frequency response, and range. This representation of the target is vector quantized using a K-means clustering algorithm. Sequences of vector quantized scattering centers as well as sequences of vector quantized range profiles are used to synthesize target specific Hidden Markov Models (HMM's). The identification decision is made by determining which HMM has the highest probability of generating the unknown sequence. The data consist of synthesized Xpatch signatures of two targets which have been difficult to separate with other RTI algorithms. The RTI algorithm developed is clearly able to separate these two targets over a 10 by 10 degree (1 degree granularity) aspect angle window off the nose for SNR's as low as 0 dB. The classification rate is 100 percent for SNR's of 5 - 20 dB, 95 percent for a SNR of 0 dB and it drops rapidly for SNR's lower than 0 dB.
Recent Tests for the Statistical Parton Distributions
NASA Astrophysics Data System (ADS)
Bourrely, Claude; Soffer, Jacques; Buccella, Franco
We compare some recent experimental results obtained at DESY, SLAC and Jefferson Lab., with the predictions of the statistical model, we have previously proposed. The result of this comparison is very satisfactory.
An adaptive detection model of moving dim targets based on energy difference between frames
NASA Astrophysics Data System (ADS)
Liu, Yuanyuan; Yan, Guoping
2009-12-01
The paper is based on biology vision stared mechanism, applies the detective arithmetic operators of static image into the system of moving dim targets detection ,brings forward an adaptive detective model of moving dim targets based on energy difference between frames, and optimizes and selects the parameters in the mathematic model. Experiments completed by the paper proving, the adaptive detective model can detect moving dim targets real-timely and exactly. Detection and tracking of moving dim targets are the most important part of the system of watching and alarming. So it's essential to find and detect the targets in time. Because of claim of detecting targets at long bowls, the targets usually are regarded as the dot targets or pixels in the system of watching and alarming. So detection of infrared dim targets is one of key technology in the weapon system, and one important project in moving targets detection. We aim at slowing down signal-to-noise ratio in the detection of moving dim targets by the way of classical frame difference and rapid matching, bring out a new anisotropic moving detection model between frames in the study of theories of biology vision fixated mechanism, and analyze and research on selection of more parameters in the detection model. Experimental results show that the algorithm based on energy difference comparing between frames which is brought out by this paper is effective and practical to detect moving dim small targets.
Application of custom tools and algorithms to the development of terrain and target models
NASA Astrophysics Data System (ADS)
Wilkosz, Aaron; Williams, Bryan L.; Motz, Steve
2003-09-01
In this paper we give a high level discussion outlining methodologies and techniques employed in generating high fidelity terrain and target models. We present the current state of our IR signature development efforts, cover custom tools and algorithms, and discuss future plans. We outline the steps required to derive an IR terrain and target signature models, and provide some details about algorithms developed to classify aerial imagery. In addition, we discuss our tool used to apply IR signature data to tactical vehicle models. We discuss how we process the empirical IR data of target vehicles, apply it to target models, and generate target signature models that correlate with the measured calibrated IR data. The developed characterization databases and target models are used in digital simulations by various customers within the US Army Aviation and Missile Command (AMCOM).
Modeling to Target Conservation Practices: A Case Study
Technology Transfer Automated Retrieval System (TEKTRAN)
Targeted placement of agricultural conservation practices within rural watersheds can significantly increase the cost-effectiveness of these nonpoint source pollution reduction measures. However, agricultural management decisions are made primarily at the farm-level, with confidentiality concerns an...
CARROLL,J.
1999-09-10
The RIKEN-BNL center workshop on ''Hard parton physics in high energy nuclear collisions'' was held at BNL from March 1st-5th! 1999. The focus of the workshop was on hard probes of nucleus-nucleus collisions that will be measured at RHIC with the PHENIX and STAR detectors. There were about 45 speakers and over 70 registered participants at the workshop, with roughly a quarter of the speakers from overseas. About 60% of the talks were theory talks. A nice overview of theory for RHIC was provided by George Sterman. The theoretical talks were on a wide range of topics in QCD which can be classified under the following: (a) energy loss and the Landau-Pomeranchuk-Migdal effect; (b) minijet production and equilibration; (c) small x physics and initial conditions; (d) nuclear parton distributions and shadowing; (e) spin physics; (f) photon, di-lepton, and charm production; and (g) hadronization, and simulations of high pt physics in event generators. Several of the experimental talks discussed the capabilities of the PHENIX and STAR detectors at RHIC in measuring high pt particles in heavy ion collisions. In general, these talks were included in the relevant theory sessions. A session was set aside to discuss the spin program at RHIC with polarized proton beams. In addition, there were speakers from 08, HERA, the fixed target experiments at Fermilab, and the CERN fixed target Pb+Pb program, who provided additional perspective on a range of issues of relevance to RHIC; from jets at the Tevatron, to saturation of parton distributions at HERA, and recent puzzling data on direct photon production in fixed target experiments, among others.
Electromagnetic modelling of Ground Penetrating Radar responses to complex targets
NASA Astrophysics Data System (ADS)
Pajewski, Lara; Giannopoulos, Antonis
2014-05-01
defined through a constant real value, or else its frequency-dispersion properties can be taken into account by incorporating into the model Debye approximations. The electromagnetic source can be represented as a simple line of current (in the case of two-dimensional models), a Hertzian dipole, a bow tie antenna, or else, the realistic description of a commercial antenna can be included in the model [2]. Preliminary results for some of the proposed cells are presented, obtained by using GprMax [3], a freeware tool which solves Maxwell's equations by using a second order in space and time Finite-Difference Time-Domain algorithm. B-Scans and A-Scans are calculated at 1.5 GHz, for the total electric field and for the field back-scattered by targets embedded in the cells. A detailed description of the structures, together with the relevant numerical results obtained to date, are available for the scientific community on the website of COST Action TU1208, www.GPRadar.eu. Research groups working on the development of electromagnetic forward- and inverse-scattering techniques, as well as on imaging methods, might test and compare the accuracy and applicability of their approaches on the proposed set of scenarios. The aim of this initiative is not that of identifying the best methods, but more properly to indicate the range of reliability of each approach, highlighting its advantages and drawbacks. In the future, the realisation of the proposed concrete cells and the acquisition of GPR experimental data would allow a very effective benchmark for forward and inverse scattering methods. References [1] R. Yelf, A. Ward, "Nine steps to concrete wisdom." Proc. 13th International Conference on Ground Penetrating Radar, Lecce, Italy, 21-25 June 2010, pp. 1-8. [2] C. Warren, A. Giannopoulos, "Creating FDTD models of commercial GPR antennas using Taguchi's optimisation method." Geophysics (2011), 76, article ID G37. [3] A. Giannopoulos, "Modelling ground penetrating radar by GPRMAX
The difficulty in measuring suitable targets when modeling victimization.
Popp, Ann Marie
2012-01-01
Target suitability is a critical theoretical concept for opportunity theory. Previous research has primarily measured this concept using demographic characteristics of the study participant, which is problematic. This study corrects the measurement problem by employing bullying variables as alternative measures of target suitability because they are arguably better at capturing the social and psychological vulnerability of the individual that is attracting motivated offenders. Using three waves (1999, 2001, & 2003) of the National Crime Victimization Survey (NCVS) School Crime Supplement (SCS), this research explores the impact of the bullying measures along with demographic characteristics and lifestyle measures on the likelihood that a student will experience victimization in school. The findings suggest that the bullying measures are better predictors of victimization over the demographic characteristics and lifestyle measures for all three waves. The findings highlight the need for better measures of target suitability, which capture the social and psychological vulnerability of victims to explain victimization. PMID:23155721
Wee partons in large nuclei: From virtual dream to hard reality
Venugopalan, R.
1995-06-01
We construct a weak coupling, many body theory to compute parton distributions in large nuclei for x {much_lt} A{sup {minus} 1/3}. The wee partons are highly coherent, non-Abelian Weizsaecker-Williams fields. Radiative corrections to the classical results axe discussed. The parton distributions for a single nucleus provide the initial conditions for the dynamical evolution of matter formed in ultrarelativistic nuclear collisions.
Investigating GPDs in the framework of the double distribution model
NASA Astrophysics Data System (ADS)
Nazari, F.; Mirjalili, A.
2016-06-01
In this paper, we construct the generalized parton distribution (GPD) in terms of the kinematical variables x, ξ, t, using the double distribution model. By employing these functions, we could extract some quantities which makes it possible to gain a three-dimensional insight into the nucleon structure function at the parton level. The main objective of GPDs is to combine and generalize the concepts of ordinary parton distributions and form factors. They also provide an exclusive framework to describe the nucleons in terms of quarks and gluons. Here, we first calculate, in the Double Distribution model, the GPD based on the usual parton distributions arising from the GRV and CTEQ phenomenological models. Obtaining quarks and gluons angular momenta from the GPD, we would be able to calculate the scattering observables which are related to spin asymmetries of the produced quarkonium. These quantities are represented by AN and ALS. We also calculate the Pauli and Dirac form factors in deeply virtual Compton scattering. Finally, in order to compare our results with the existing experimental data, we use the difference of the polarized cross-section for an initial longitudinal leptonic beam and unpolarized target particles (ΔσLU). In all cases, our obtained results are in good agreement with the available experimental data.
Modeling Criterion Shifts and Target Checking in Prospective Memory Monitoring
ERIC Educational Resources Information Center
Horn, Sebastian S.; Bayen, Ute J.
2015-01-01
Event-based prospective memory (PM) involves remembering to perform intended actions after a delay. An important theoretical issue is whether and how people monitor the environment to execute an intended action when a target event occurs. Performing a PM task often increases the latencies in ongoing tasks. However, little is known about the…
Selected topics on parton distribution functions
Hirai, M.; Saito, K.; Kawamura, H.; Kumano, S.
2011-12-14
We report recent studies on structure functions of the nucleon and nuclei. First, clustering effects are investigated in the structure function F{sub 2} of {sup 9}Be for explaining an unusual nuclear correction found in a JLab experiment. We propose that high densities created by formation of clustering structure like 2{alpha}+neutron in {sup 9}Be is the origin of the unexpected JLab result by using the antisymmetrized molecular dynamics (AMD). There is an approved proposal at JLab to investigate the structure functions of light nuclei including the cluster structure, so that much details will become clear in a few years. Second, tensor-polarized quark and antiquark distributions are obtained by analyzing HERMES measurements on the structure function b{sub 1} for the deuteron. The result suggests a finite tensor polarization for antiquark distributions, which is an interesting topic for further theoretical and experimental investigations. An experimental proposal exists at JLab for measuring b{sub 1} of the deuteron as a new tensor-structure study in 2010's. Furthermore, the antiquark tensor polarization could be measured by polarized deuteron Drell-Yan processes at hadron facilities such as J-PARC and GSI-FAIR. Third, the recent CDF dijet anomaly is investigated within the standard model by considering possible modifications of the strange-quark distribution. We find that the shape of a dijet-mass spectrum changes depending on the strange-quark distribution. It indicates that the CDF excess could be partially explained as a PDF effect, particularly by the strangeness in the nucleon, within the standard model if the excess at m{sub jj}{approx_equal}140 GeV is not a sharp peak.
Westendorff, Stephanie; Kuang, Shenbing; Taghizadeh, Bahareh; Donchin, Opher; Gail, Alexander
2015-04-01
Different error signals can induce sensorimotor adaptation during visually guided reaching, possibly evoking different neural adaptation mechanisms. Here we investigate reach adaptation induced by visual target errors without perturbing the actual or sensed hand position. We analyzed the spatial generalization of adaptation to target error to compare it with other known generalization patterns and simulated our results with a neural network model trained to minimize target error independent of prediction errors. Subjects reached to different peripheral visual targets and had to adapt to a sudden fixed-amplitude displacement ("jump") consistently occurring for only one of the reach targets. Subjects simultaneously had to perform contralateral unperturbed saccades, which rendered the reach target jump unnoticeable. As a result, subjects adapted by gradually decreasing reach errors and showed negative aftereffects for the perturbed reach target. Reach errors generalized to unperturbed targets according to a translational rather than rotational generalization pattern, but locally, not globally. More importantly, reach errors generalized asymmetrically with a skewed generalization function in the direction of the target jump. Our neural network model reproduced the skewed generalization after adaptation to target jump without having been explicitly trained to produce a specific generalization pattern. Our combined psychophysical and simulation results suggest that target jump adaptation in reaching can be explained by gradual updating of spatial motor goal representations in sensorimotor association networks, independent of learning induced by a prediction-error about the hand position. The simulations make testable predictions about the underlying changes in the tuning of sensorimotor neurons during target jump adaptation. PMID:25609106
Jo, H S; Girod, F X; Avakian, H; Burkert, V D; Garçon, M; Guidal, M; Kubarovsky, V; Niccolai, S; Stoler, P; Adhikari, K P; Adikaram, D; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Ball, J; Baltzell, N A; Battaglieri, M; Batourine, V; Bedlinskiy, I; Biselli, A S; Boiarinov, S; Briscoe, W J; Brooks, W K; Carman, D S; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Compton, N; Contalbrigo, M; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Dupre, R; Alaoui, A El; Fassi, L El; Elouadrhiri, L; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guegan, B; Guler, N; Guo, L; Hafidi, K; Hakobyan, H; Harrison, N; Hattawy, M; Hicks, K; Hirlinger Saylor, N; Ho, D; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Joo, K; Joosten, S; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Kuhn, S E; Kuleshov, S V; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; McKinnon, B; Meziani, Z E; Mirazita, M; Mokeev, V; Montgomery, R A; Moutarde, H; Movsisyan, A; Munevar, E; Munoz Camacho, C; Nadel-Turonski, P; Net, L A; Niculescu, G; Osipenko, M; Ostrovidov, A I; Paolone, M; Park, K; Pasyuk, E; Phillips, J J; Pisano, S; Pogorelko, O; Price, J W; Procureur, S; Prok, Y; Puckett, A J R; Raue, B A; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Seder, E; Simonyan, A; Skorodumina, Iu; Smith, G D; Sokhan, D; Sparveris, N; Stepanyan, S; Strakovsky, I I; Strauch, S; Sytnik, V; Tian, Ye; Tkachenko, S; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zhao, Z W; Zonta, I
2015-11-20
Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}. PMID:26636848
Transverse Momentum-Dependent Parton Distributions From Lattice QCD
Michael Engelhardt, Bernhard Musch, Philipp Haegler, Andreas Schaefer
2012-12-01
Starting from a definition of transverse momentum-dependent parton distributions for semi-inclusive deep inelastic scattering and the Drell-Yan process, given in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection, a scheme to determine such observables in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are presented, focusing in particular on their dependence on the staple extent and the Collins-Soper evolution parameter.
The Generalized Parton Distribution Program at Jefferson Lab
C. Munoz Camacho
2010-05-01
Recent results on the Generalized Parton Distribution (GPD) program at Jefferson Lab (JLab) will be presented. The emphasis will be in the Hall A program aiming at measuring Q^2-dependences of different terms of the Deeply Virtual Compton Scattering (DVCS) cross section. This is a fundamental step before one can extract GPD information from JLab DVCS data. The upcoming program in Hall A, using both a 6 GeV beam (2010) and a 11 GeV beam (~2015) will also be described.
Pion and kaon valence-quark parton distribution functions
NASA Astrophysics Data System (ADS)
Nguyen, Trang; Bashir, Adnan; Roberts, Craig D.; Tandy, Peter C.
2011-06-01
A rainbow-ladder truncation of QCD’s Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to π-N Drell-Yan data for the pion’s u-quark distribution and to Drell-Yan data for the ratio uK(x)/uπ(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
Pion and kaon valence-quark parton distribution functions.
Nguyen, T.; Bashir, A.; Roberts, C. D.; Tandy, P. C.
2011-06-16
A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
Pion and kaon valence-quark parton distribution functions
Nguyen, Trang; Bashir, Adnan; Roberts, Craig D.; Tandy, Peter C.
2011-06-15
A rainbow-ladder truncation of QCD's Dyson-Schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence-quark parton distribution functions of the pion and kaon. Comparison is made to {pi}-N Drell-Yan data for the pion's u-quark distribution and to Drell-Yan data for the ratio u{sub K}(x)/u{sub {pi}}(x): the environmental influence of this quantity is a parameter-free prediction, which agrees well with existing data. Our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons.
NASA Astrophysics Data System (ADS)
Friedman, Melvin
2014-05-01
The problem solved in this paper is easily stated: for a scenario with 𝑛 networked and moving imaging sensors, 𝑚 moving targets and 𝑘 independent observers searching imagery produced by the 𝑛 moving sensors, analytically model system target acquisition probability for each target as a function of time. Information input into the model is the time dependence of 𝘗∞ and 𝜏, two parameters that describe observer-sensor-atmosphere-range-target properties of the target acquisition system for the case where neither the sensor nor target is moving. The parameter 𝘗∞ can be calculated by the NV-IPM model and 𝜏 is estimated empirically from 𝘗∞. In this model 𝑛, 𝑚 and 𝑘 are integers and 𝑘 can be less than, equal to or greater than 𝑛. Increasing 𝑛 and 𝑘 results in a substantial increase in target acquisition probabilities. Because the sensors are networked, a target is said to be detected the moment the first of the 𝑘 observers declares the target. The model applies to time-limited or time-unlimited search, and applies to any imaging sensors operating in any wavelength band provided each sensor can be described by 𝘗∞ and 𝜏 parameters.
NASA Astrophysics Data System (ADS)
Billy, Frédérique; Clairambault, Jean; Fercoq, Olivier; Lorenzi, Tommaso; Lorz, Alexander; Perthame, Benoît
2012-09-01
The main two pitfalls of therapeutics in clinical oncology, that limit increasing drug doses, are unwanted toxic side effects on healthy cell populations and occurrence of resistance to drugs in cancer cell populations. Depending on the constraint considered in the control problem at stake, toxicity or drug resistance, we present two different ways to model the evolution of proliferating cell populations, healthy and cancer, under the control of anti-cancer drugs. In the first case, we use a McKendrick age-structured model of the cell cycle, whereas in the second case, we use a model of evolutionary dynamics, physiologically structured according to a continuous phenotype standing for drug resistance. In both cases, we mention how drug targets may be chosen so as to accurately represent the effects of cytotoxic and of cytostatic drugs, separately, and how one may consider the problem of optimisation of combined therapies.
Adaptive target detection in foliage-penetrating SAR images using alpha-stable models.
Banerjee, A; Burlina, P; Chellappa, R
1999-01-01
Detecting targets occluded by foliage in foliage-penetrating (FOPEN) ultra-wideband synthetic aperture radar (UWB SAR) images is an important and challenging problem. Given the different nature of target returns in foliage and nonfoliage regions and very low signal-to-clutter ratio in UWB imagery, conventional detection algorithms fail to yield robust target detection results. A new target detection algorithm is proposed that (1) incorporates symmetric alpha-stable (SalphaS) distributions for accurate clutter modeling, (2) constructs a two-dimensional (2-D) site model for deriving local context, and (3) exploits the site model for region-adaptive target detection. Theoretical and empirical evidence is given to support the use of the SalphaS model for image segmentation and constant false alarm rate (CFAR) detection. Results of our algorithm on real FOPEN images collected by the Army Research Laboratory are provided. PMID:18267459
LHAPDF6: parton density access in the LHC precision era
NASA Astrophysics Data System (ADS)
Buckley, Andy; Ferrando, James; Lloyd, Stephen; Nordström, Karl; Page, Ben; Rüfenacht, Martin; Schönherr, Marek; Watt, Graeme
2015-03-01
The Fortran LHAPDF library has been a long-term workhorse in particle physics, providing standardised access to parton density functions for experimental and phenomenological purposes alike, following on from the venerable PDFLIB package. During Run 1 of the LHC, however, several fundamental limitations in LHAPDF's design have became deeply problematic, restricting the usability of the library for important physics-study procedures and providing dangerous avenues by which to silently obtain incorrect results. In this paper we present the LHAPDF 6 library, a ground-up re-engineering of the PDFLIB/LHAPDF paradigm for PDF access which removes all limits on use of concurrent PDF sets, massively reduces static memory requirements, offers improved CPU performance, and fixes fundamental bugs in multi-set access to PDF metadata. The new design, restricted for now to interpolated PDFs, uses centralised numerical routines and a powerful cascading metadata system to decouple software releases from provision of new PDF data and allow completely general parton content. More than 200 PDF sets have been migrated from LHAPDF 5 to the new universal data format, via a stringent quality control procedure. LHAPDF 6 is supported by many Monte Carlo generators and other physics programs, in some cases via a full set of compatibility routines, and is recommended for the demanding PDF access needs of LHC Run 2 and beyond.
A new approach to parton recombination in the QCD evolution equations
NASA Astrophysics Data System (ADS)
Wei Zhu
1999-06-01
Parton recombination is reconsidered in perturbation theory without using the AGK cutting rules in the leading order of the recombination. We use time-ordered perturbation theory to sum the cut diagrams, which are neglected in the GLR evolution equation. We present a set of new evolution equations including parton recombination.
Partonic Equations of State in High-Energy Nuclear Collisions atRHIC
Xu, Nu
2006-10-01
The authors discuss the recent results on equation of state for partonic matter created at RHIC. Issues of partonic collectivity for multi-strange hadrons and J/{psi} from Au + Au collisions at {radical}s{sub NN} = 200 GeV are the focus of this paper.
How large is the gluon polarization in the statistical parton distributions approach?
Soffer, Jacques; Bourrely, Claude; Buccella, Franco
2015-04-10
We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.
How large is the gluon polarization in the statistical parton distributions approach?
NASA Astrophysics Data System (ADS)
Soffer, Jacques; Bourrely, Claude; Buccella, Franco
2015-04-01
We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.
CAD Model and Visual Assisted Control System for NIF Target Area Positioners
Tekle, E A; Wilson, E F; Paik, T S
2007-10-03
The National Ignition Facility (NIF) target chamber contains precision motion control systems that reach up to 6 meters into the target chamber for handling targets and diagnostics. Systems include the target positioner, an alignment sensor, and diagnostic manipulators (collectively called positioners). Target chamber shot experiments require a variety of positioner arrangements near the chamber center to be aligned to an accuracy of 10 micrometers. Positioners are some of the largest devices in NIF, and they require careful monitoring and control in 3 dimensions to prevent interferences. The Integrated Computer Control System provides efficient and flexible multi-positioner controls. This is accomplished through advanced video-control integration incorporating remote position sensing and realtime analysis of a CAD model of target chamber devices. The control system design, the method used to integrate existing mechanical CAD models, and the offline test laboratory used to verify proper operation of the control system are described.
Tang, Jing; Aittokallio, Tero
2014-01-01
Polypharmacology has emerged as novel means in drug discovery for improving treatment response in clinical use. However, to really capitalize on the polypharmacological effects of drugs, there is a critical need to better model and understand how the complex interactions between drugs and their cellular targets contribute to drug efficacy and possible side effects. Network graphs provide a convenient modeling framework for dealing with the fact that most drugs act on cellular systems through targeting multiple proteins both through on-target and off-target binding. Network pharmacology models aim at addressing questions such as how and where in the disease network should one target to inhibit disease phenotypes, such as cancer growth, ideally leading to therapies that are less vulnerable to drug resistance and side effects by means of attacking the disease network at the systems level through synergistic and synthetic lethal interactions. Since the exponentially increasing number of potential drug target combinations makes pure experimental approach quickly unfeasible, this review depicts a number of computational models and algorithms that can effectively reduce the search space for determining the most promising combinations for experimental evaluation. Such computational-experimental strategies are geared toward realizing the full potential of multi-target treatments in different disease phenotypes. Our specific focus is on system-level network approaches to polypharmacology designs in anticancer drug discovery, where we give representative examples of how network-centric modeling may offer systematic strategies toward better understanding and even predicting the phenotypic responses to multi-target therapies.
Hydrodynamic modeling of laser interaction with micro-structured targets
NASA Astrophysics Data System (ADS)
Velechovsky, J.; Limpouch, J.; Liska, R.; Tikhonchuk, V.
2016-09-01
A model is developed for numerical simulations of laser absorption in plasmas made of porous materials, with particular interest in low-density foams. Laser absorption is treated on two spatial scales simultaneously. At the microscale, the expansion of a thin solid pore wall is modeled in one dimension and the information obtained is used in the macroscale fluid simulations for the description of the plasma homogenization behind the ionization front. This two-scale laser absorption model is implemented in the arbitrary Lagrangian–Eulerian hydrocode PALE. The numerical simulations of laser penetration into low-density foams compare favorably with published experimental data.
Hydrodynamic modeling of laser interaction with micro-structured targets
Velechovsky, Jan; Limpouch, Jiri; Liska, Richard; Tikhonchuk, Vladimir
2016-08-03
A model is developed for numerical simulations of laser absorption in plasmas made of porous materials, with particular interest in low-density foams. Laser absorption is treated on two spatial scales simultaneously. At the microscale, the expansion of a thin solid pore wall is modeled in one dimension and the information obtained is used in the macroscale fluid simulations for the description of the plasma homogenization behind the ionization front. This two-scale laser absorption model is implemented in the arbitrary Lagrangian–Eulerian hydrocode PALE. In conclusion, the numerical simulations of laser penetration into low-density foams compare favorably with published experimental data.
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sectionsmore » $$\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$$ for the $$ep\\to e^\\prime p^\\prime \\gamma$$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.« less
Jo, Hyon -Suk
2015-11-17
Unpolarized and beam-polarized four-fold cross sections $\\frac{d^4 \\sigma}{dQ^2 dx_B dt d\\phi}$ for the $ep\\to e^\\prime p^\\prime \\gamma$ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 ($Q^2,x_B,t$) bins over the widest phase space ever explored in the valence-quark region. Several models of Generalized Parton Distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD $H$, expected to be the dominant contributor to these observables. Thus, through a leading-twist extraction of Compton Form Factors, these results reveal a tomographic image of the nucleon.
Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature
Melican, Keira; Aubey, Flore; Duménil, Guillaume
2014-01-01
Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood vessels resulting in vascular leak, the development of purpuric rashes and eventual tissue necrosis. Studying the pathogenesis of this infection was previously limited by the human specificity of the bacteria, which makes in vivo models difficult. In this protocol, we describe a humanized model for this infection in which human skin, containing dermal microvessels, is grafted onto immunocompromised mice. These vessels anastomose with the mouse circulation while maintaining their human characteristics. Once introduced into this model, N. meningitidis adhere exclusively to the human vessels, resulting in extensive vascular damage, inflammation and in some cases the development of purpuric rash. This protocol describes the grafting, infection and evaluation steps of this model in the context of N. meningitidis infection. The technique may be applied to numerous human specific pathogens that infect the blood stream. PMID:24747976
The primary target model of energetic ions penetration in thin botanic samples
NASA Astrophysics Data System (ADS)
Wang, Yugang; Du, Guanghua; Xue, Jianming; Liu, Feng; Wang, Sixue; Yan, Sha; Zhao, Weijiang
2002-08-01
The ion transmission spectra of very low current MeV H + ions through two kinds of botanic samples, kidney bean slices and onion endocuticle, were carried out. The experimental spectra confirmed the botanic sample is inhomogeneous in mass density. A target model with local density approximation was suggested to describe the penetration of the energetic ions in such kind of materials. From the fitting of proton transmission spectra of two-energies, this target model was verified primarily. Including the influence of surface roughness and irradiation damage, this target model could be improved to predict the profile of penetration depth and range distribution of the energetic ions in the botanic samples.
Modeling the behavior of a light-water production reactor target rod
Sherwood, D.J.
1992-03-01
Pacific Northwest Laboratory has been conducting a series of in-reactor experiments in the Idaho National Engineering Laboratory (INEL) Advanced Test Reactor (ATR) to determine the amount of tritium released by permeation from a target rod under neutron irradiation. The model discussed in this report was developed from first principles to model the behavior of the first target rod irradiated in the ATR. The model can be used to determine predictive relationships for the amount of tritium that permeates through the target rod cladding during irradiation. The model consists of terms and equations for tritium production, gettering, partial pressure, and permeation, all of which are described in this report. The model addressed only the condition of steady state and features only a single adjustable parameter. The target rod design for producing tritium in a light-water reactor was tested first in the WC-1 in-reactor experiment. During irradiation, tritium is generated in the target rod within the ceramic lithium target material. The target rod has been engineered to limit the release of tritium to the reactor coolant during normal operations. The engineered features are a nickel-plated Zircaloy-4 getter and a barrier coating on the cladding surfaces. The ceramic target is wrapped with the getter material and the resulting ``pencils`` are inserted into the barrier coated cladding. These features of the rod are described in the report, along with the release of tritium from the ceramic target. The steady-state model could be useful for the design procedure of target rod components.
Modeling the behavior of a light-water production reactor target rod
Sherwood, D.J.
1992-03-01
Pacific Northwest Laboratory has been conducting a series of in-reactor experiments in the Idaho National Engineering Laboratory (INEL) Advanced Test Reactor (ATR) to determine the amount of tritium released by permeation from a target rod under neutron irradiation. The model discussed in this report was developed from first principles to model the behavior of the first target rod irradiated in the ATR. The model can be used to determine predictive relationships for the amount of tritium that permeates through the target rod cladding during irradiation. The model consists of terms and equations for tritium production, gettering, partial pressure, and permeation, all of which are described in this report. The model addressed only the condition of steady state and features only a single adjustable parameter. The target rod design for producing tritium in a light-water reactor was tested first in the WC-1 in-reactor experiment. During irradiation, tritium is generated in the target rod within the ceramic lithium target material. The target rod has been engineered to limit the release of tritium to the reactor coolant during normal operations. The engineered features are a nickel-plated Zircaloy-4 getter and a barrier coating on the cladding surfaces. The ceramic target is wrapped with the getter material and the resulting pencils'' are inserted into the barrier coated cladding. These features of the rod are described in the report, along with the release of tritium from the ceramic target. The steady-state model could be useful for the design procedure of target rod components.
NASA Astrophysics Data System (ADS)
Dehmollaian, Mojtaba
This thesis focuses on the application of radio waves for detection and recognition of visually obscured targets. To provide practical solutions, comprehensive forward and inverse models are needed to capture and exploit the physical phenomena involved. These models must accurately simulate wave propagation in the environment in which the target is imbedded, scattering from the target and wave interaction of the medium scatterers and the target. In this dissertation, two problems of major importance are investigated. The first problem is detection of complex targets camouflaged inside forest and the second problem pertains to imaging of building interiors and detection of targets within. In the early chapters, a hybrid target-foliage model is developed to investigate the scattering behavior of hard targets embedded inside a forest canopy. This model is composed of two parts, one for foliage and the other for hard targets. The connection between these two models that accounts for the first-order interaction between the foliage scatterers and the target is accomplished through the application of the reciprocity theorem. The foliage penetration model is based on the coherent single scattering theory, developed previously. The target scattering model is based on either exact numerical finite difference time domain technique or high frequency asymptotic iterative physical optics approximation. Having the hybrid target-foliage model, a polarization synthesis optimization method for improving signal to clutter ratio is presented, using genetic algorithms. In the later chapters, the problem of through-wall imaging using the synthetic aperture radar technique by employing ultra wideband antennas and scanning over a wide range of incidence angles is investigated. Theoretical and experimental studies on the effects of different walls on point target images are carried out and refocusing approaches are introduced to remove the wall effects and restore the image resolution
Inorganic Nanovehicle Targets Tumor in an Orthotopic Breast Cancer Model
NASA Astrophysics Data System (ADS)
Choi, Goeun; Kwon, Oh-Joon; Oh, Yeonji; Yun, Chae-Ok; Choy, Jin-Ho
2014-03-01
The clinical efficacy of conventional chemotherapeutic agent, methotrexate (MTX), can be limited by its very short plasma half-life, the drug resistance, and the high dosage required for cancer cell suppression. In this study, a new drug delivery system is proposed to overcome such limitations. To realize such a system, MTX was intercalated into layered double hydroxides (LDHs), inorganic drug delivery vehicle, through a co-precipitation route to produce a MTX-LDH nanohybrid with an average particle size of approximately 130 nm. Biodistribution studies in mice bearing orthotopic human breast tumors revealed that the tumor-to-liver ratio of MTX in the MTX-LDH-treated-group was 6-fold higher than that of MTX-treated-one after drug treatment for 2 hr. Moreover, MTX-LDH exhibited superior targeting effect resulting in high antitumor efficacy inducing a 74.3% reduction in tumor volume compared to MTX alone, and as a consequence, significant survival benefits. Annexin-V and propidium iodine dual staining and TUNEL analysis showed that MTX-LDH induced a greater degree of apoptosis than free MTX. Taken together, our data demonstrate that a new MTX-LDH nanohybrid exhibits a superior efficacy profile and improved distribution compared to MTX alone and has the potential to enhance therapeutic efficacy via inhibition of tumor proliferation and induction of apoptosis.
Inorganic Nanovehicle Targets Tumor in an Orthotopic Breast Cancer Model
Choi, Goeun; Kwon, Oh-Joon; Oh, Yeonji; Yun, Chae-Ok; Choy, Jin-Ho
2014-01-01
The clinical efficacy of conventional chemotherapeutic agent, methotrexate (MTX), can be limited by its very short plasma half-life, the drug resistance, and the high dosage required for cancer cell suppression. In this study, a new drug delivery system is proposed to overcome such limitations. To realize such a system, MTX was intercalated into layered double hydroxides (LDHs), inorganic drug delivery vehicle, through a co-precipitation route to produce a MTX-LDH nanohybrid with an average particle size of approximately 130 nm. Biodistribution studies in mice bearing orthotopic human breast tumors revealed that the tumor-to-liver ratio of MTX in the MTX-LDH-treated-group was 6-fold higher than that of MTX-treated-one after drug treatment for 2 hr. Moreover, MTX-LDH exhibited superior targeting effect resulting in high antitumor efficacy inducing a 74.3% reduction in tumor volume compared to MTX alone, and as a consequence, significant survival benefits. Annexin-V and propidium iodine dual staining and TUNEL analysis showed that MTX-LDH induced a greater degree of apoptosis than free MTX. Taken together, our data demonstrate that a new MTX-LDH nanohybrid exhibits a superior efficacy profile and improved distribution compared to MTX alone and has the potential to enhance therapeutic efficacy via inhibition of tumor proliferation and induction of apoptosis. PMID:24651154
Inorganic nanovehicle targets tumor in an orthotopic breast cancer model.
Choi, Goeun; Kwon, Oh-Joon; Oh, Yeonji; Yun, Chae-Ok; Choy, Jin-Ho
2014-01-01
The clinical efficacy of conventional chemotherapeutic agent, methotrexate (MTX), can be limited by its very short plasma half-life, the drug resistance, and the high dosage required for cancer cell suppression. In this study, a new drug delivery system is proposed to overcome such limitations. To realize such a system, MTX was intercalated into layered double hydroxides (LDHs), inorganic drug delivery vehicle, through a co-precipitation route to produce a MTX-LDH nanohybrid with an average particle size of approximately 130 nm. Biodistribution studies in mice bearing orthotopic human breast tumors revealed that the tumor-to-liver ratio of MTX in the MTX-LDH-treated-group was 6-fold higher than that of MTX-treated-one after drug treatment for 2 hr. Moreover, MTX-LDH exhibited superior targeting effect resulting in high antitumor efficacy inducing a 74.3% reduction in tumor volume compared to MTX alone, and as a consequence, significant survival benefits. Annexin-V and propidium iodine dual staining and TUNEL analysis showed that MTX-LDH induced a greater degree of apoptosis than free MTX. Taken together, our data demonstrate that a new MTX-LDH nanohybrid exhibits a superior efficacy profile and improved distribution compared to MTX alone and has the potential to enhance therapeutic efficacy via inhibition of tumor proliferation and induction of apoptosis. PMID:24651154
Hepatic or splenic targeting of carrier erythrocytes: a murine model
Zocchi, E.; Guida, L.; Benatti, U.; Canepa, M.; Borgiani, L.; Zanin, T.; De Flora, A.
1987-10-01
Carrier mouse erythrocytes, i.e., red cells, subjected to a dialysis technique involving transient hypotonic hemolysis and isotonic resealing were treated in vitro in three different ways: (a) energy depletion by exposure for 90 min at 42 degrees C; (b) desialylation by incubation with neuroaminidase; and (c) oxidative stress by incubation with H/sub 2/O/sub 2/ and NaN3. Procedure (c) afforded maximal damage, as shown by analysis of biochemical properties of the treated erythrocytes. Reinfusion in mice of the variously manipulated erythrocytes following their /sup 51/Cr labeling showed extensive fragilization as indicated by rapid clearance of radioactivity from the circulation. Moreover, both the energy-depleted and the neuraminidase-treated erythrocytes showed a preferential liver uptake, reaching 50 and 75%, respectively, within 2 h. On the other hand, exposure of erythrocytes to the oxidant stress triggered a largely splenic removal, accounting for almost 40% of the reinjected cells within 4 h. Transmission electron microscopy of liver from mice receiving energy-depleted erythrocytes demonstrated remarkable erythrocyte congestion within the sinusoids, followed by hyperactivity of Kupffer cells and by subsequent thickening of the perisinusoidal Disse space. Concomitantly, levels of serum transaminase activities were moderately increased. Each of the three procedures of manipulation of carrier erythrocytes may prove applicable under conditions where selective targeting of erythrocyte-encapsulated chemicals and drugs to either the liver or the spleen has to be achieved.
Impact modeling and prediction of attacks on cyber targets
NASA Astrophysics Data System (ADS)
Khalili, Aram; Michalk, Brian; Alford, Lee; Henney, Chris; Gilbert, Logan
2010-04-01
In most organizations, IT (information technology) infrastructure exists to support the organization's mission. The threat of cyber attacks poses risks to this mission. Current network security research focuses on the threat of cyber attacks to the organization's IT infrastructure; however, the risks to the overall mission are rarely analyzed or formalized. This connection of IT infrastructure to the organization's mission is often neglected or carried out ad-hoc. Our work bridges this gap and introduces analyses and formalisms to help organizations understand the mission risks they face from cyber attacks. Modeling an organization's mission vulnerability to cyber attacks requires a description of the IT infrastructure (network model), the organization mission (business model), and how the mission relies on IT resources (correlation model). With this information, proper analysis can show which cyber resources are of tactical importance in a cyber attack, i.e., controlling them enables a large range of cyber attacks. Such analysis also reveals which IT resources contribute most to the organization's mission, i.e., lack of control over them gravely affects the mission. These results can then be used to formulate IT security strategies and explore their trade-offs, which leads to better incident response. This paper presents our methodology for encoding IT infrastructure, organization mission and correlations, our analysis framework, as well as initial experimental results and conclusions.
Modelling Sensor and Target effects on LiDAR Waveforms
NASA Astrophysics Data System (ADS)
Rosette, J.; North, P. R.; Rubio, J.; Cook, B. D.; Suárez, J.
2010-12-01
The aim of this research is to explore the influence of sensor characteristics and interactions with vegetation and terrain properties on the estimation of vegetation parameters from LiDAR waveforms. This is carried out using waveform simulations produced by the FLIGHT radiative transfer model which is based on Monte Carlo simulation of photon transport (North, 1996; North et al., 2010). The opportunities for vegetation analysis that are offered by LiDAR modelling are also demonstrated by other authors e.g. Sun and Ranson, 2000; Ni-Meister et al., 2001. Simulations from the FLIGHT model were driven using reflectance and transmittance properties collected from the Howland Research Forest, Maine, USA in 2003 together with a tree list for a 200m x 150m area. This was generated using field measurements of location, species and diameter at breast height. Tree height and crown dimensions of individual trees were calculated using relationships established with a competition index determined for this site. Waveforms obtained by the Laser Vegetation Imaging Sensor (LVIS) were used as validation of simulations. This provided a base from which factors such as slope, laser incidence angle and pulse width could be varied. This has enabled the effect of instrument design and laser interactions with different surface characteristics to be tested. As such, waveform simulation is relevant for the development of future satellite LiDAR sensors, such as NASA’s forthcoming DESDynI mission (NASA, 2010), which aim to improve capabilities of vegetation parameter estimation. ACKNOWLEDGMENTS We would like to thank scientists at the Biospheric Sciences Branch of NASA Goddard Space Flight Center, in particular to Jon Ranson and Bryan Blair. This work forms part of research funded by the NASA DESDynI project and the UK Natural Environment Research Council (NE/F021437/1). REFERENCES NASA, 2010, DESDynI: Deformation, Ecosystem Structure and Dynamics of Ice. http
Inferring multi-target QSAR models with taxonomy-based multi-task learning
2013-01-01
Background A plethora of studies indicate that the development of multi-target drugs is beneficial for complex diseases like cancer. Accurate QSAR models for each of the desired targets assist the optimization of a lead candidate by the prediction of affinity profiles. Often, the targets of a multi-target drug are sufficiently similar such that, in principle, knowledge can be transferred between the QSAR models to improve the model accuracy. In this study, we present two different multi-task algorithms from the field of transfer learning that can exploit the similarity between several targets to transfer knowledge between the target specific QSAR models. Results We evaluated the two methods on simulated data and a data set of 112 human kinases assembled from the public database ChEMBL. The relatedness between the kinase targets was derived from the taxonomy of the humane kinome. The experiments show that multi-task learning increases the performance compared to training separate models on both types of data given a sufficient similarity between the tasks. On the kinase data, the best multi-task approach improved the mean squared error of the QSAR models of 58 kinase targets. Conclusions Multi-task learning is a valuable approach for inferring multi-target QSAR models for lead optimization. The application of multi-task learning is most beneficial if knowledge can be transferred from a similar task with a lot of in-domain knowledge to a task with little in-domain knowledge. Furthermore, the benefit increases with a decreasing overlap between the chemical space spanned by the tasks. PMID:23842210
Healthy latrine development model to achieve MDGs target
NASA Astrophysics Data System (ADS)
Soedjono, Eddy S.; Arumsari, Nurvita
2014-03-01
A case happened in Pungging sub-district was one example of low level healthy habits of East Java inhabitants. According to the data of Mojokerto district Health Service until the end of 2010, there are 219 families (or about 8% of total families in Pungging sub-district) which do not have their own latrine. Moreover, if we observe closely to their prosperity level, the percentage of disadvantaged families and prosperous level I is still adequately high about 29,54% of the total number of families in Pungging sub-district. Accordingly, comprehensive studies related to basic sanitation requirement need to be done, not only in the matter of quantity but also in the matter of quality. Furthermore, further studies on people's knowledge and understanding on healthy sanitation also needed in the effort to understand people's demand to own latrine (willingness to pay) and ability to pay. Consequently, the design of healthy latrine which agrees with people's demand and ability is needed in order to achieve the target of Open Defecation Free (ODF) in 2015. The research methodology includes literary study, data collection, data analysis, and healthy latrine design. Out of 75 respondents, only 32% of them who attended counselling program on healthy latrine and only 48% of them who have knowledge on healthy latrine, but in reality 96% of respondents stated that healthy latrine is important. Healthy latrine, according to the respondents, is a place of defecation (BAB) which has components like latrine bowl or septic tank. Estimation on WTP distribution which is divided in two categories; low category with range of willingness to pay from IDR 0 to IDR 200,000 is IDR 90,048,000. On the other hand, high category with range of willingness to pay more than IDR 1,000,000 is IDR 749,964,768. Estimation on respondents' ATP in the area of study on the sanitation maintenance service is from IDR 7,000 to IDR 30,000.
Model-based approach to real-time target detection
NASA Astrophysics Data System (ADS)
Hackett, Jay K.; Gold, Ed V.; Long, Daniel T.; Cloud, Eugene L.; Duvoisin, Herbert A.
1992-09-01
Land mine detection and extraction from infra-red (IR) scenes using real-time parallel processing is of significant interest to ground based infantry. The mine detection algorithms consist of several sub-processes to progress from raw input IR imagery to feature based mine nominations. Image enhancement is first applied; this consists of noise and sensor artifact removal. Edge grouping is used to determine the boundary of the objects. The generalized Hough Transform tuned to the land mine signature acts as a model based matched nomination filter. Once the object is found, the model is used to guide the labeling of each pixel as background, object, or object boundary. Using these labels to identify object regions, feature primitives are extracted in a high speed parallel processor. A feature based screener then compares each object's feature primitives to acceptable values and rejects all objects that do not resemble mines. This operation greatly reduces the number of objects that must be passed from a real-time parallel processor to the classifier. We will discuss details of this model- based approach, including results from actual IR field test imagery.
Hsu, Janet; Hoenicka, Janet; Muro, Silvia
2016-01-01
Purpose Delivery of therapeutics to neurons is paramount to treat neurological conditions, including many lysosomal storage disorders. However, key aspects of drug-carrier behavior in neurons are relatively unknown: the occurrence of non-canonical endocytic pathways (present in other cells); whether carriers that traverse the blood-brain barrier are, contrarily, retained within neurons; if neuron-surface receptors are accessible to bulky carriers compared to small ligands; or if there are differences regarding neuronal compartments (neuron body vs. neurites) pertaining said parameters. We have explored these questions using model polymer nanocarriers targeting intercellular adhesion molecule-1 (ICAM-1). Methods Differentiated human neuroblastoma cells were incubated with anti-ICAM-coated polystyrene nanocarriers and analyzed by fluorescence microscopy. Results ICAM-1 expression and nanocarrier binding was enhanced in altered (TNFα) vs. control conditions. While small ICAM-1 ligands (anti-ICAM) preferentially accessed the cell body, anti-ICAM nanocarriers bound with faster kinetics to neurites, yet reached similar saturation over time. Anti-ICAM nanocarriers were also endocytosed with faster kinetics and lower saturation levels in neurites. Non-classical cell adhesion molecule (CAM) endocytosis ruled uptake, and neurite-to-cell body transport was inferred. Nanocarriers trafficked to lysosomes, delivering active enzymes (dextranase) with substrate reduction in a lysosomal-storage disease model. Conclusion ICAM-1-targeting holds potential for intracellular delivery of therapeutics to neurons. PMID:25319100
The Brain-Targeted Teaching Model for 21st-Century Schools
ERIC Educational Resources Information Center
Hardiman, Mariale
2012-01-01
"The Brain-Targeted Teaching Model for 21st-Century Schools" serves as a bridge between research and practice by providing a cohesive, proven, and usable model of effective instruction. Compatible with other professional development programs, this model shows how to apply relevant research from educational and cognitive neuroscience to classroom…
ERIC Educational Resources Information Center
Thomas, Emily; Reznik, Gayle; Dawes, William
This paper argues that a typical use of regression models to target student recruitment efforts is theoretically unsound and may therefore be operationally inefficient. It presents results from a study using a predictive model to identify the prospective students on whom recruitment efforts have the greatest impact. The model uses four kinds of…
Generalized parton distributions and rapidity gap survival in exclusive diffractive pp scattering
Leonid Frankfurt; Charles Hyde-Wright; Mark Strikman; Christian Weiss
2007-03-01
We propose a new approach to the problem of rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, heavy quarkonium, Higgs boson) in double-gap exclusive diffractive pp scattering, pp-->p + (gap) + H + (gap) + p. It is based on the idea that hard and soft interactions proceed over widely different time- and distance scales and are thus approximately independent. The high-mass system is produced in a hard scattering process with exchange of two gluons between the protons. Its amplitude is calculable in terms of the gluon generalized parton distributions (GPDs) in the protons, which can be measured in J= production in exclusive ep scattering. The hard scattering process is modified by soft spectator interactions, which we calculate in a model-independent way in terms of the pp elastic scattering amplitude. Contributions from inelastic intermediate states are suppressed. A simple geometric picture of the interplay of hard and soft interactions in diffraction is obtained. The onset of the black-disk limit in pp scattering at TeV energies strongly suppresses diffraction at small impact parameters and is the main factor in determining the RGS probability. Correlations between hard and soft interactions (e.g. due to scattering from the long-range pion field of the proton, or due to possible short-range transverse correlations between partons) further decrease the RGS probability. We also investigate the dependence of the diffractive cross section on the transverse momenta of the final-state protons (''diffraction pattern''). By measuring this dependence one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton. Such studies appear to be feasible with the planned forward detectors at the LHC.
Experimental models for cellular radiation targets: LET, RBE and radioprotectors
NASA Technical Reports Server (NTRS)
Lett, J. T.; Chatterjee, A. (Principal Investigator)
1996-01-01
The topics of this presentation are: a brief review of the early research, the ideas it stimulated and the ways they are used in current efforts to explain cellular radiosensitivity; an analysis of the strengths and weaknesses of two experimental models used in vitro for simulating the induction of double strand breaks (DSB) and single strand breaks (SSB) in situ. Note that when alkali is used to denature cellular DNA for the determination of strand breaks, both overt SSB and the SSB that result from DSB in the denaturation process are recorded as total strand breaks (TSB). All information is taken from published literature.
Targeting Forest Management through Fire and Erosion Modeling
NASA Astrophysics Data System (ADS)
Elliot, William J.; Miller, Mary Ellen; MacDonald, Lee H.
2013-04-01
Forests deliver a number of ecosystem services, including clean water. When forests are disturbed by wildfire, the timing and quantity of runoff can be altered, and the quality can be severely degraded. A modeling study for about 1500 km2 in the Upper Mokelumne River Watershed in California was conducted to determine the risk of wildfire and the associated potential sediment delivery should a wildfire occur, and to calculate the potential reduction in sediment delivery that might result from fuel reduction treatments. The first step was to predict wildfire severity and probability of occurrence under current vegetation conditions with FlamMap fire prediction tool. FlamMap uses current vegetation, topography, and wind characteristics to predict the speed, flame length, and direction of a simulated flame front for each 30-m pixel. As the first step in the erosion modeling, a geospatial interface for the WEPP model (GeoWEPP) was used to delineate approximately 6-ha hillslope polygons for the study area. The flame length values from FlamMap were then aggregated for each hillslope polygon to yield a predicted fire intensity. Fire intensity and pre-fire vegetation conditions were used to estimate fire severity (either unburned, low, moderate or high). The fire severity was combined with soil properties from the STATSGO database to build the vegetation and soil files needed to run WEPP for each polygon. Eight different stochastic climates were generated to account for the weather variability within the basin. A modified batching version of GeoWEPP was used to predict the first-year post-fire sediment yield from each hillslope and subwatershed. Estimated sediment yields ranged from 0 to more than 100 Mg/ha, and were typical of observed values. The polygons that generated the greatest amount of sediment or that were critical for reducing fire spread were identified, and these were "treated" by reducing the amount of fuel available for a wildfire. The erosion associated with
Westendorff, Stephanie; Kuang, Shenbing; Taghizadeh, Bahareh; Donchin, Opher
2015-01-01
Different error signals can induce sensorimotor adaptation during visually guided reaching, possibly evoking different neural adaptation mechanisms. Here we investigate reach adaptation induced by visual target errors without perturbing the actual or sensed hand position. We analyzed the spatial generalization of adaptation to target error to compare it with other known generalization patterns and simulated our results with a neural network model trained to minimize target error independent of prediction errors. Subjects reached to different peripheral visual targets and had to adapt to a sudden fixed-amplitude displacement (“jump”) consistently occurring for only one of the reach targets. Subjects simultaneously had to perform contralateral unperturbed saccades, which rendered the reach target jump unnoticeable. As a result, subjects adapted by gradually decreasing reach errors and showed negative aftereffects for the perturbed reach target. Reach errors generalized to unperturbed targets according to a translational rather than rotational generalization pattern, but locally, not globally. More importantly, reach errors generalized asymmetrically with a skewed generalization function in the direction of the target jump. Our neural network model reproduced the skewed generalization after adaptation to target jump without having been explicitly trained to produce a specific generalization pattern. Our combined psychophysical and simulation results suggest that target jump adaptation in reaching can be explained by gradual updating of spatial motor goal representations in sensorimotor association networks, independent of learning induced by a prediction-error about the hand position. The simulations make testable predictions about the underlying changes in the tuning of sensorimotor neurons during target jump adaptation. PMID:25609106
Transverse momentum-dependent parton distribution functions in lattice QCD
Engelhardt, Michael G.; Musch, Bernhard U.; Haegler, Philipp G.; Negele, John W.; Schaefer, Andreas
2013-08-01
A fundamental structural property of the nucleon is the distribution of quark momenta, both parallel as well as perpendicular to its propagation. Experimentally, this information is accessible via selected processes such as semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process (DY), which can be parametrized in terms of transversemomentum-dependent parton distributions (TMDs). On the other hand, these distribution functions can be extracted from nucleon matrix elements of a certain class of bilocal quark operators in which the quarks are connected by a staple-shaped Wilson line serving to incorporate initial state (DY) or final state (SIDIS) interactions. A scheme for evaluating such matrix elements within lattice QCD is developed. This requires casting the calculation in a particular Lorentz frame, which is facilitated by a parametrization of the matrix elements in terms of invariant amplitudes. Exploratory results are presented for the time-reversal odd Sivers and Boer-Mulders transverse momentum shifts.
Double parton effects for jets with large rapidity separation
Szczurek, Antoni; Cisek, Anna; Maciuła, Rafal
2015-04-10
We discuss production of four jets pp → jjjjX with at least two jets with large rapidity separation in proton-proton collisions at the LHC through the mechanism of double-parton scattering (DPS). The cross section is calculated in a factorizaed approximation. Each hard subprocess is calculated in LO collinear approximation. The LO pQCD calculations are shown to give a reasonably good descritption of CMS and ATLAS data on inclusive jet production. It is shown that relative contribution of DPS is growing with increasing rapidity distance between the most remote jets, center-of-mass energy and with decreasing (mini)jet transverse momenta. We show also result for angular azimuthal dijet correlations calculated in the framework of k{sub t} -factorization approximation.
Transverse momentum-dependent parton distribution functions from lattice QCD
Michael Engelhardt, Philipp Haegler, Bernhard Musch, John Negele, Andreas Schaefer
2012-12-01
Transverse momentum-dependent parton distributions (TMDs) relevant for semi-inclusive deep inelastic scattering (SIDIS) and the Drell-Yan process can be defined in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection. Starting from such a definition, a scheme to determine TMDs in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are obtained using ensembles at the pion masses 369MeV and 518MeV, focusing in particular on the dependence of these shifts on the staple extent and a Collins-Soper-type evolution parameter quantifying proximity of the staples to the light cone.
Global NLO Analysis of Nuclear Parton Distribution Functions
Hirai, M.; Kumano, S.; Nagai, T.-H.
2008-02-21
Nuclear parton distribution functions (NPDFs) are determined by a global analysis of experimental measurements on structure-function ratios F{sub 2}{sup A}/F{sub 2}{sup A{sup '}} and Drell-Yan cross section ratios {sigma}{sub DY}{sup A}/{sigma}{sub DY}{sup A{sup '}}, and their uncertainties are estimated by the Hessian method. The NPDFs are obtained in both leading order (LO) and next-to-leading order (NLO) of {alpha}{sub s}. As a result, valence-quark distributions are relatively well determined, whereas antiquark distributions at x>0.2 and gluon distributions in the whole x region have large uncertainties. The NLO uncertainties are slightly smaller than the LO ones; however, such a NLO improvement is not as significant as the nucleonic case.
Iterative Monte Carlo analysis of spin-dependent parton distributions
NASA Astrophysics Data System (ADS)
Sato, Nobuo; Melnitchouk, W.; Kuhn, S. E.; Ethier, J. J.; Accardi, A.; Jefferson Lab Angular Momentum Collaboration
2016-04-01
We present a comprehensive new global QCD analysis of polarized inclusive deep-inelastic scattering, including the latest high-precision data on longitudinal and transverse polarization asymmetries from Jefferson Lab and elsewhere. The analysis is performed using a new iterative Monte Carlo fitting technique which generates stable fits to polarized parton distribution functions (PDFs) with statistically rigorous uncertainties. Inclusion of the Jefferson Lab data leads to a reduction in the PDF errors for the valence and sea quarks, as well as in the gluon polarization uncertainty at x ≳0.1 . The study also provides the first determination of the flavor-separated twist-3 PDFs and the d2 moment of the nucleon within a global PDF analysis.
Maneuvering target tracking algorithm based on current statistical model in three dimensional space
NASA Astrophysics Data System (ADS)
Huang, Ligang; Yan, Kang; Wang, Xiangdong
2015-07-01
This paper is mainly to solve the problems associated with maneuvering target tracking based current statistical model in three dimensional space. Firstly, a three-dimensional model of the nine state variables is presented. Then adaptive Kalman filtering algorithm is designed with the motor acceleration data mean and variance. Finally, A simulation about the adaptive Kalman filtering put forward by this thesis and the direct calculation method is given, which aim at the maneuvering target in three-dimension. The results show the good performances such as better target position, velocity and acceleration estimates brought by the proposed approach by presenting and discussing the simulation results.
Drug-target interaction prediction: databases, web servers and computational models.
Chen, Xing; Yan, Chenggang Clarence; Zhang, Xiaotian; Zhang, Xu; Dai, Feng; Yin, Jian; Zhang, Yongdong
2016-07-01
Identification of drug-target interactions is an important process in drug discovery. Although high-throughput screening and other biological assays are becoming available, experimental methods for drug-target interaction identification remain to be extremely costly, time-consuming and challenging even nowadays. Therefore, various computational models have been developed to predict potential drug-target associations on a large scale. In this review, databases and web servers involved in drug-target identification and drug discovery are summarized. In addition, we mainly introduced some state-of-the-art computational models for drug-target interactions prediction, including network-based method, machine learning-based method and so on. Specially, for the machine learning-based method, much attention was paid to supervised and semi-supervised models, which have essential difference in the adoption of negative samples. Although significant improvements for drug-target interaction prediction have been obtained by many effective computational models, both network-based and machine learning-based methods have their disadvantages, respectively. Furthermore, we discuss the future directions of the network-based drug discovery and network approach for personalized drug discovery based on personalized medicine, genome sequencing, tumor clone-based network and cancer hallmark-based network. Finally, we discussed the new evaluation validation framework and the formulation of drug-target interactions prediction problem by more realistic regression formulation based on quantitative bioactivity data. PMID:26283676
Electron structure: Shape, size, and generalized parton distributions in QED
NASA Astrophysics Data System (ADS)
Miller, Gerald A.
2014-12-01
The shape of the electron is studied using lowest-order perturbation theory. Quantities used to probe the structure of the proton—form factors, generalized parton distributions, transverse densities, Wigner distributions and the angular momentum content—are computed for the electron-photon component of the electron wave function. The influence of longitudinally polarized photons, demanded by the need for infrared regularization via a nonzero photon mass, is included. The appropriate value of the photon mass depends on experimental conditions, and consequently the size of the electron (as defined by the slope of its Dirac form factor) bound in a hydrogen atom is found to be about four times larger than when the electron is in a continuum scattering state. The shape of the electron, as determined from the transverse density and generalized parton distributions, is shown not to be round, and the continuum electron is shown to be far less round than the bound electron. An electron distribution function (analogous to the quark distribution function) is defined, and that of the bound electron is shown to be suppressed compared to that of the continuum electron. If the relative transverse momentum of the virtual electron and photon is large compared with the electron mass, the virtual electron and photon each carry nearly the total angular momentum of the physical electron (1 /2 ), with the orbital angular momentum being nearly (-1 /2 ). Including the nonzero photon mass leads to the suppression of end-point contributions to form factors. Implications for proton structure and color transparency are discussed.
Hot electron transport modelling in fast ignition relevant targets with non-Spitzer resistivity
NASA Astrophysics Data System (ADS)
Chapman, D. A.; Hughes, S. J.; Hoarty, D. J.; Swatton, D. J. R.
2010-08-01
The simple Lee-More model for electrical resistivity is implemented in the hybrid fast electron transport code THOR. The model is shown to reproduce experimental data across a wide range of temperatures using a small number of parameters. The effect of this model on the heating of simple Al targets by a short-pulse laser is studied and compared to the predictions of the classical Spitzer-Härm resistivity. The model is then used in simulations of hot electron transport experiments using buried layer targets.
Knowledge-based approach for generating target system specifications from a domain model
NASA Technical Reports Server (NTRS)
Gomaa, Hassan; Kerschberg, Larry; Sugumaran, Vijayan
1992-01-01
Several institutions in industry and academia are pursuing research efforts in domain modeling to address unresolved issues in software reuse. To demonstrate the concepts of domain modeling and software reuse, a prototype software engineering environment is being developed at George Mason University to support the creation of domain models and the generation of target system specifications. This prototype environment, which is application domain independent, consists of an integrated set of commercial off-the-shelf software tools and custom-developed software tools. This paper describes the knowledge-based tool that was developed as part of the environment to generate target system specifications from a domain model.
A Target Model Construction Algorithm for Robust Real-Time Mean-Shift Tracking
Choi, Yoo-Joo; Kim, Yong-Goo
2014-01-01
Mean-shift tracking has gained more interests, nowadays, aided by its feasibility of real-time and reliable tracker implementation. In order to reduce background clutter interference to mean-shift object tracking, this paper proposes a novel indicator function generation method. The proposed method takes advantage of two ‘a priori’ knowledge elements, which are inherent to a kernel support for initializing a target model. Based on the assured background labels, a gradient-based label propagation is performed, resulting in a number of objects differentiated from the background. Then the proposed region growing scheme picks up one largest target object near the center of the kernel support. The grown object region constitutes the proposed indicator function and this allows an exact target model construction for robust mean-shift tracking. Simulation results demonstrate the proposed exact target model could significantly enhance the robustness as well as the accuracy of mean-shift object tracking. PMID:25372619
Theory of high-energy electron scattering by composite targets
Coester, F.
1988-01-01
The emphasis of these expository lectures is on the role of relativistic invariance and the unity of the theory for medium and high energies. Sec. 2 introduces the kinematic notation and provides an elementary derivation of the general cross section. The relevant properties of the Poincare group and the transformation properties of current operators and target states are described in Sec 3. In Sec. 4 representations of target states with kinematic light-front symmetry are briefly discussed. The focus is on two applications. An impulse approximation of inclusive electron nucleus scattering at both medium and high energies. A parton model of the proton applied to deep inelastic scattering of polarized electrons by polarized protons. 19 refs.
Designing and modeling a centrifugal microfluidic device to separate target blood cells
NASA Astrophysics Data System (ADS)
Shamloo, Amir; Selahi, AmirAli; Madadelahi, Masoud
2016-03-01
The objective of this study is to design a novel and efficient portable lab-on-a-CD (LOCD) microfluidic device for separation of specific cells (target cells) using magnetic beads. In this study the results are shown for neutrophils as target cells. However, other kinds of target cells can be separated in a similar approach. The designed microfluidics can be utilized as a point of care system for neutrophil detection. This microfluidic system employs centrifugal and magnetic forces for separation. After model validation by the experimental data in the literature (that may be used as a design tool for developing centrifugo-magnetophoretic devices), two models are presented for separation of target cells using magnetic beads. The first model consists of one container in the inlet section and two containers in the outlets. Initially, the inlet container is filled with diluted blood sample which is a mixture of red blood cells (RBCs) plus neutrophils which are attached to Magnetic beads. It is shown that by using centrifugal and magnetic forces, this model can separate all neutrophils with recovery factor of ~100%. In the second model, due to excess of magnetic beads in usual experimental analysis (to ensure that all target cells are attached to them) the geometry is improved by adding a third outlet for these free magnetic beads. It is shown that at angular velocity of 45 rad s-1, recovery factor of 100% is achievable for RBCs, free magnetic beads and neutrophils as target cells.
Computational Modeling and Neuroimaging Techniques for Targeting during Deep Brain Stimulation
Sweet, Jennifer A.; Pace, Jonathan; Girgis, Fady; Miller, Jonathan P.
2016-01-01
Accurate surgical localization of the varied targets for deep brain stimulation (DBS) is a process undergoing constant evolution, with increasingly sophisticated techniques to allow for highly precise targeting. However, despite the fastidious placement of electrodes into specific structures within the brain, there is increasing evidence to suggest that the clinical effects of DBS are likely due to the activation of widespread neuronal networks directly and indirectly influenced by the stimulation of a given target. Selective activation of these complex and inter-connected pathways may further improve the outcomes of currently treated diseases by targeting specific fiber tracts responsible for a particular symptom in a patient-specific manner. Moreover, the delivery of such focused stimulation may aid in the discovery of new targets for electrical stimulation to treat additional neurological, psychiatric, and even cognitive disorders. As such, advancements in surgical targeting, computational modeling, engineering designs, and neuroimaging techniques play a critical role in this process. This article reviews the progress of these applications, discussing the importance of target localization for DBS, and the role of computational modeling and novel neuroimaging in improving our understanding of the pathophysiology of diseases, and thus paving the way for improved selective target localization using DBS. PMID:27445709
A Model for the Detection of Moving Targets in Visual Clutter Inspired by Insect Physiology
Wiederman, Steven D.; Shoemaker, Patrick A.; O'Carroll, David C.
2008-01-01
We present a computational model for target discrimination based on intracellular recordings from neurons in the fly visual system. Determining how insects detect and track small moving features, often against cluttered moving backgrounds, is an intriguing challenge, both from a physiological and a computational perspective. Previous research has characterized higher-order neurons within the fly brain, known as ‘small target motion detectors’ (STMD), that respond robustly to moving features, even when the velocity of the target is matched to the background (i.e. with no relative motion cues). We recorded from intermediate-order neurons in the fly visual system that are well suited as a component along the target detection pathway. This full-wave rectifying, transient cell (RTC) reveals independent adaptation to luminance changes of opposite signs (suggesting separate ON and OFF channels) and fast adaptive temporal mechanisms, similar to other cell types previously described. From this physiological data we have created a numerical model for target discrimination. This model includes nonlinear filtering based on the fly optics, the photoreceptors, the 1st order interneurons (Large Monopolar Cells), and the newly derived parameters for the RTC. We show that our RTC-based target detection model is well matched to properties described for the STMDs, such as contrast sensitivity, height tuning and velocity tuning. The model output shows that the spatiotemporal profile of small targets is sufficiently rare within natural scene imagery to allow our highly nonlinear ‘matched filter’ to successfully detect most targets from the background. Importantly, this model can explain this type of feature discrimination without the need for relative motion cues. PMID:18665213
Development of a target-site based regional frequency model using historical information
NASA Astrophysics Data System (ADS)
Hamdi, Yasser; Bardet, Lise; Duluc, Claire-Marie; Rebour, Vincent
2016-04-01
Nuclear power facilities in France were designed to withstand extreme environmental conditions with a very low probability of failure. Nevertheless, some exceptional surges considered as outliers are not properly addressed by classical frequency analysis models. If available data at the site of interest (target-site) is sufficiently complete on a long period and not characterized by the presence of an outlier, at-site frequency analysis can be used to estimate quantiles with acceptable uncertainties. Otherwise, regional and historical information (HI) may be used to mitigate the lack of data and the influence of the outlier by increasing its representativeness in the sample. several models have been proposed over the last years for regional extreme surges frequency analysis in France to take into account these outliers in the frequency analysis. However, these models do not give a specific weight to the target site and cannot take into account HI. The objective of the present work is to develop a regional frequency model (RFM) centered on a target-site and using HI. The neighborhood between sites is measured by a degree of physical and statistical dependence between observations (with a prior confidence level). Unlike existing models, the obtained region around the target site (and constituting the neighboring sites) is sliding from a target-site to another. In other words, the developed model assigns a region for each target site. The idea behind the construction of a frequency model favoring target sites and the principle of moving regions around these target-sites is the original key point of the developed model. A related issue regards the estimation of missed and/or ungauged surges at target-sites from those of gauged potential neighboring sites, a multiple linear regression (MLR) is used and it can be extended to other reconstitutions models. MLR analysis can be considered conclusive only if available observations at neighboring sites are informative enough
Jung, Joe; Longcope, Donald B.; Tabbara, Mazen R.
1999-05-03
A procedure has been developed to represent the loading on a penetrator and its motion during oblique penetration into geologic media. The penetrator is modeled with the explicit dynamics, finite element computer program PRONTO 3D and the coupled pressure on the penetrator is given in a new loading option based on a separate cavity expansion (CE) solution that accounts for the pressure-reduction from a nearby target free surface. The free-surface influ- ence distance is selected in a predictive manner by considering the pressure to expand a spherical cavity in a finite radius sphere of the target material. The CE/PRONTO 3D procedure allows a detailed description of the penetrator for predicting shock environments or structural failure dur- ing the entire penetration event and is sufficiently rapid to be used in design optimization. It has been evaluated by comparing its results with data from two field tests of a full-scale penetrator into frozen soil at an impact angles of 49.6 and 52.5 degrees from the horizontal. The measured penetrator rotations were 24 and 22 degrees, respectively. In the simulation, the rotation was21 degrees and predominately resulted from the pressure reduction of the free surface. Good agree- ment was also found for the penetration depth and axial and lateral acceleration at two locations in the penetrator.
NASA Astrophysics Data System (ADS)
Herschtal, A.; Foroudi, F.; Greer, P. B.; Eade, T. N.; Hindson, B. R.; Kron, T.
2012-05-01
Early approaches to characterizing errors in target displacement during a fractionated course of radiotherapy assumed that the underlying fraction-to-fraction variability in target displacement, known as the ‘treatment error’ or ‘random error’, could be regarded as constant across patients. More recent approaches have modelled target displacement allowing for differences in random error between patients. However, until recently it has not been feasible to compare the goodness of fit of alternate models of random error rigorously. This is because the large volumes of real patient data necessary to distinguish between alternative models have only very recently become available. This work uses real-world displacement data collected from 365 patients undergoing radical radiotherapy for prostate cancer to compare five candidate models for target displacement. The simplest model assumes constant random errors across patients, while other models allow for random errors that vary according to one of several candidate distributions. Bayesian statistics and Markov Chain Monte Carlo simulation of the model parameters are used to compare model goodness of fit. We conclude that modelling the random error as inverse gamma distributed provides a clearly superior fit over all alternatives considered. This finding can facilitate more accurate margin recipes and correction strategies.
A physical model eye with 3D resolution test targets for optical coherence tomography
NASA Astrophysics Data System (ADS)
Hu, Zhixiong; Liu, Wenli; Hong, Baoyu; Hao, Bingtao; Wang, Lele; Li, Jiao
2014-09-01
Optical coherence tomography (OCT) has been widely employed as non-invasive 3D imaging diagnostic instrument, particularly in the field of ophthalmology. Although OCT has been approved for use in clinic in USA, Europe and Asia, international standardization of this technology is still in progress. Validation of OCT imaging capabilities is considered extremely important to ensure its effective use in clinical diagnoses. Phantom with appropriate test targets can assist evaluate and calibrate imaging performance of OCT at both installation and throughout lifetime of the instrument. In this paper, we design and fabricate a physical model eye with 3D resolution test targets to characterize OCT imaging performance. The model eye was fabricated with transparent resin to simulate realistic ophthalmic testing environment, and most key optical elements including cornea, lens and vitreous body were realized. The test targets which mimic USAF 1951 test chart were fabricated on the fundus of the model eye by 3D printing technology. Differing from traditional two dimensional USAF 1951 test chart, a group of patterns which have different thickness in depth were fabricated. By measuring the 3D test targets, axial resolution as well as lateral resolution of an OCT system can be evaluated at the same time with this model eye. To investigate this specialized model eye, it was measured by a scientific spectral domain OCT instrument and a clinical OCT system respectively. The results demonstrate that the model eye with 3D resolution test targets have the potential of qualitatively and quantitatively validating the performance of OCT systems.
3D modelling of the electromagnetic response of geophysical targets using the FDTD method
Debroux, P.S.
1996-05-01
A publicly available and maintained electromagnetic finite-difference time domain (FDTD) code has been applied to the forward modelling of the response of 1D, 2D and 3D geophysical targets to a vertical magnetic dipole excitation. The FDTD method is used to analyze target responses in the 1 MHz to 100 MHz range, where either conduction or displacement currents may have the controlling role. The response of the geophysical target to the excitation is presented as changes in the magnetic field ellipticity. The results of the FDTD code compare favorably with previously published integral equation solutions of the response of 1D targets, and FDTD models calculated with different finite-difference cell sizes are compared to find the effect of model discretization on the solution. The discretization errors, calculated as absolute error in ellipticity, are presented for the different ground geometry models considered, and are, for the most part, below 10% of the integral equation solutions. Finally, the FDTD code is used to calculate the magnetic ellipticity response of a 2D survey and a 3D sounding of complicated geophysical targets. The response of these 2D and 3D targets are too complicated to be verified with integral equation solutions, but show the proper low- and high-frequency responses.
Human search for a target on a textured background is consistent with a stochastic model.
Clarke, Alasdair D F; Green, Patrick; Chantler, Mike J; Hunt, Amelia R
2016-05-01
Previous work has demonstrated that search for a target in noise is consistent with the predictions of the optimal search strategy, both in the spatial distribution of fixation locations and in the number of fixations observers require to find the target. In this study we describe a challenging visual-search task and compare the number of fixations required by human observers to find the target to predictions made by a stochastic search model. This model relies on a target-visibility map based on human performance in a separate detection task. If the model does not detect the target, then it selects the next saccade by randomly sampling from the distribution of saccades that human observers made. We find that a memoryless stochastic model matches human performance in this task. Furthermore, we find that the similarity in the distribution of fixation locations between human observers and the ideal observer does not replicate: Rather than making the signature doughnut-shaped distribution predicted by the ideal search strategy, the fixations made by observers are best described by a central bias. We conclude that, when searching for a target in noise, humans use an essentially random strategy, which achieves near optimal behavior due to biases in the distributions of saccades we have a tendency to make. The findings reconcile the existence of highly efficient human search performance with recent studies demonstrating clear failures of optimality in single and multiple saccade tasks. PMID:27145531
An evaluation of the PENCURV model for penetration events in complex targets.
Broyles, Todd P.
2004-07-01
Three complex target penetration scenarios are run with a model developed by the U. S. Army Engineer Waterways Experiment Station, called PENCURV. The results are compared with both test data and a Zapotec model to evaluate PENCURV's suitability for conducting broad-based scoping studies on a variety of targets to give first order solutions to the problem of G-loading. Under many circumstances, the simpler, empirically based PENCURV model compares well with test data and the much more sophisticated Zapotec model. The results suggest that, if PENCURV were enhanced to include rotational acceleration in its G-loading computations, it would provide much more accurate solutions for a wide variety of penetration problems. Data from an improved PENCURV program would allow for faster, lower cost optimization of targets, test parameters and penetration bodies as Sandia National Laboratories continues in its evaluation of the survivability requirements for earth penetrating sensors and weapons.
ERIC Educational Resources Information Center
Thompson, Bruce
2006-01-01
Value-added models, which rate schools for effectiveness while taking into account the poverty and other socioeconomic status of the students, are generating increased interest. This paper describes the use of one such model to evaluate whether school ratings changed when three new programs were introduced: the "Target Teach" curriculum alignment,…
A model for sonar interrogation of complex bottom and surface targets in shallow-water waveguides.
Giddings, Thomas E; Shirron, Joseph J
2008-04-01
Many problems of current interest in underwater acoustics involve low-frequency broadband sonar interrogation of objects near the sea surface or sea floor of a shallow-water environment. When the target is situated near the upper or lower boundary of the water column the acoustic interactions with the target objects are complicated by interactions with the nearby free surface or fluid-sediment interface, respectively. A practical numerical method to address such situations is presented. The model provides high levels of accuracy with the flexibility to handle complex, three-dimensional targets in range-independent environments. The model is demonstrated using several bottom target scenarios, with and without locally undulating seabeds. The impact of interface and boundary interactions is considered with an eye toward using the sonar return signal as the basis for acoustic imaging or spectral classification. PMID:18397010
An empirical target discharging model for direct-drive implosions on OMEGA
NASA Astrophysics Data System (ADS)
Sinenian, N.; Manuel, M. J.-E.; Frenje, J. A.; Seguin, F. H.; Li, C. K.; Petrasso, R. D.; Goncharov, V.; Delettrez, J.; Stoeckl, C.; Sangster, T. C.; Cobble, J.
2012-10-01
Capsule charging of inertial confinement fusion (ICF) targets, observed previously on OMEGA, is detrimental to achieving the high areal densities (ρR) required for ignition and gain. This is because the target potential traps energetic electrons that can preheat the fuel, raise the adiabat and degrade compression. The decay-time of this potential is therefore an important parameter for preheat calculations. A non-linear model of the electrical discharging of ICF capsules has been developed. The empirical model, which captures the essential dynamics of the target voltage decay, incorporates previous charged-particle spectroscopic and radiographic measurements of the fields. It is shown that return currents through the target support fiber have a profound effect on the voltage-decay time. Implications of these findings for inertial fusion energy (IFE) are considered. This work was supported in part by DOE, LLE and LLNL.
Onunka, Chiemela; Nnadozie, Remigius Chidozie
2013-12-01
The performance of frequency modulated continuous wave (FMCW) radar in tracking targets is presented and analysed. Obstacle detection, target tracking and radar target tracking performance models are developed and were used to investigate and to propose ways of improving the autonomous motion of unmanned surface vehicle (USV). Possible factors affecting the performance of FMCW radar in tracking targets are discussed and analysed. PMID:23853743
Advanced EMI models for survey data processing: targets detection and classification
NASA Astrophysics Data System (ADS)
Shubitidze, F.; Barrowes, B. E.; Wang, Yinlin; Shamatava, Irma; Sigman, J. B.; O'Neill, K.
2016-05-01
This paper describes procedures and approaches our team took to demonstrate the capability of advanced electromagnetic induction (EMI) forward and inverse models to perform subsurface metallic objects picking and classification at live-UXO sites from dynamic data sets. Over the past seven years, blind classification tests at live-UXO sites have revealed two main challenges: 1) consistent selection of targets for cued interrogation, (e.g., for the recent SWPG2 study, two independent performers that processed the same MetalMapper dynamic data picked different targets for cued interrogation); and 2) positioning of the cued sensor close enough to the actual cued target to accurately perform classification (particularly when multiple targets or magnetic soils are present). To overcome these problems, in this paper we introduced an innovative and robust approach for subsurface metallic targets picking and classification from dynamic data sets. This approach first inverts for target locations and polarizabilities from each dynamic data point, and then clusters the inverted locations and defines each cluster as a target/source. Finally, the method uses the extracted polarizabilities for classifying UXO from non-UXO items. The studies are done for the 2x2 TEMTADS dynamic data set collected at Camp Hale, CO. The targets picking and classification results are illustrated and validated against ground truth.
Sze, N N; Wong, S C; Lee, C Y
2014-12-01
In past several decades, many countries have set quantified road safety targets to motivate transport authorities to develop systematic road safety strategies and measures and facilitate the achievement of continuous road safety improvement. Studies have been conducted to evaluate the association between the setting of quantified road safety targets and road fatality reduction, in both the short and long run, by comparing road fatalities before and after the implementation of a quantified road safety target. However, not much work has been done to evaluate whether the quantified road safety targets are actually achieved. In this study, we used a binary logistic regression model to examine the factors - including vehicle ownership, fatality rate, and national income, in addition to level of ambition and duration of target - that contribute to a target's success. We analyzed 55 quantified road safety targets set by 29 countries from 1981 to 2009, and the results indicate that targets that are in progress and with lower level of ambitions had a higher likelihood of eventually being achieved. Moreover, possible interaction effects on the association between level of ambition and the likelihood of success are also revealed. PMID:25255417
Target Mass Corrections Revisited
W. Melnitchouk; F. Steffens
2006-03-07
We propose a new implementation of target mass corrections to nucleon structure functions which, unlike existing treatments, has the correct kinematic threshold behavior at finite Q{sup 2} in the x {yields} 1 limit. We illustrate the differences between the new approach and existing prescriptions by considering specific examples for the F{sub 2} and F{sub L} structure functions, and discuss the broader implications of our results, which call into question the notion of universal parton distribution at finite Q{sup 2}.
Albright, Brian J; Yin, Lin; Hegelich, Bjoorn M; Bowers, Kevin J; Huang, Chengkun; Fernandez, Juan C; Flippo, Kirk A; Gaillard, Sandrine; Kwan, Thomas J T; Henig, Andreas; Yan, Xue Q; Tajima, Toshi; Habs, Dieter
2009-01-01
A simple model has been derived for the expansion of a thin (up to 100s of nm thickness), solid-density target driven by an u.ltraintense laser. In this regime, new ion acceleration mechanisms, such as the Break-Out Afterburner (BOA) [1], emerge with the potential to dramatically improve energy, efficiency, and energy spread of laser-driven ion beams. Such beams have been proposed [2] as drivers for fast ignition inertial confinement fusion [3]. Analysis of kinetic simulations of the BOA shows two dislinct times that bound the period of enhanced acceleration: t{sub 1}, when the target becomes relativistically transparent to the laser, and t{sub 2}, when the target becomes classically underdense and the enhanced acceleration terminates. A silllple dynamical model for target expansion has been derived that contains both the early, one-dimensional (lD) expansion of the target as well as three-dimensional (3D) expansion of the plasma at late times, The model assumes that expansion is slab-like at the instantaneous ion sound speed and requires as input target composition, laser intensity, laser spot area, and the efficiency of laser absorption into electron thermal energy.
NASA Astrophysics Data System (ADS)
Albright, B. J.; Yin, L.; Hegelich, B. M.; Bowers, K. J.; Huang, C.; Henig, A.; Fernández, J. C.; Flippo, K. A.; Gaillard, S. A.; Kwan, T. J. T.; Yan, X. Q.; Tajima, T.; Habs, D.
2010-08-01
A simple model has been derived for expansion of a thin (up to 100s of nm thickness) target initially of solid density irradiated by an ultraintense laser. In this regime, ion acceleration mechanisms, such as the Break-Out Afterburner (BOA) [1], emerge with the potential for dramatically improved energy, efficiency, and energy spread. Ion beams have been proposed [2] as drivers for fast ignition inertial confinement fusion [3]. Analysis of kinetic simulations of the BOA shows the period of enhanced acceleration occurs between times t1, when the target becomes relativistically transparent to the laser, and t2, when the target becomes classically underdense and the enhanced acceleration terminates. A simple model for target expansion has been derived that contains early, one-dimensional (1D) expansion of the target and three-dimensional (3D) expansion at late times. The model assumes expansion is slab-like at the instantaneous ion sound speed and requires as input target composition, laser intensity, laser spot area, and the efficiency of laser absorption into electron thermal energy.
Masked target transform volume clutter metric for human observer visual search modeling
NASA Astrophysics Data System (ADS)
Moore, Richard Kirk
The Night Vision and Electronic Sensors Directorate (NVESD) develops an imaging system performance model to aid in the design and comparison of imaging systems for military use. It is intended to approximate visual task performance for a typical human observer with an imaging system of specified optical, electrical, physical, and environmental parameters. When modeling search performance, the model currently uses only target size and target-to-background contrast to describe a scene. The presence or absence of other non-target objects and textures in the scene also affect search performance, but NVESD's targeting task performance metric based time limited search model (TTP/TLS) does not currently account for them explicitly. Non-target objects in a scene that impact search performance are referred to as clutter. A universally accepted mathematical definition of clutter does not yet exist. Researchers have proposed a number of clutter metrics based on very different methods, but none account for display geometry or the varying spatial frequency sensitivity of the human visual system. After a review of the NVESD search model, properties of the human visual system, and a literature review of clutter metrics, the new masked target transform volume clutter metric will be presented. Next the results of an experiment designed to show performance variation due to clutter alone will be presented. Then, the results of three separate perception experiments using real or realistic search imagery will be used to show that the new clutter metric better models human observer search performance than the current NVESD model or any of the reviewed clutter metrics.
Polar versus Cartesian velocity models for maneuvering target tracking with IMM
NASA Astrophysics Data System (ADS)
Laneuville, Dann
This paper compares various model sets in different IMM filters for the maneuvering target tracking problem. The aim is to see whether we can improve the tracking performance of what is certainly the most widely used model set in the literature for the maneuvering target tracking problem: a Nearly Constant Velocity model and a Nearly Coordinated Turn model. Our new challenger set consists of a mixed Cartesian position and polar velocity state vector to describe the uniform motion segments and is augmented with the turn rate to obtain the second model for the maneuvering segments. This paper also gives a general procedure to discretize up to second order any non-linear continuous time model with linear diffusion. Comparative simulations on an air defence scenario with a 2D radar, show that this new approach improves significantly the tracking performance in this case.
a Positive Test for Fermi-Dirac Distributions of Quark-Partons
NASA Astrophysics Data System (ADS)
Buccella, Franco; Pisanti, Ofelia; Rosa, Luigi; Dorsner, Ilya; Santorelli, Pietro
By describing a large class of deep inelastic processes with standard parametrization for the different parton species, we check the characteristic relationship dictated by Pauli principle: broader shapes for higher first moments. Indeed, the ratios between the second and the first moments and the one between the third and the second moments for the valence partons is an increasing function of the first moment and agrees quantitatively with the values found with Fermi-Dirac distributions.
Zago, Myrka; Bosco, Gianfranco; Maffei, Vincenzo; Iosa, Marco; Ivanenko, Yuri P; Lacquaniti, Francesco
2004-04-01
Prevailing views on how we time the interception of a moving object assume that the visual inputs are informationally sufficient to estimate the time-to-contact from the object's kinematics. Here we present evidence in favor of a different view: the brain makes the best estimate about target motion based on measured kinematics and an a priori guess about the causes of motion. According to this theory, a predictive model is used to extrapolate time-to-contact from expected dynamics (kinetics). We projected a virtual target moving vertically downward on a wide screen with different randomized laws of motion. In the first series of experiments, subjects were asked to intercept this target by punching a real ball that fell hidden behind the screen and arrived in synchrony with the visual target. Subjects systematically timed their motor responses consistent with the assumption of gravity effects on an object's mass, even when the visual target did not accelerate. With training, the gravity model was not switched off but adapted to nonaccelerating targets by shifting the time of motor activation. In the second series of experiments, there was no real ball falling behind the screen. Instead the subjects were required to intercept the visual target by clicking a mousebutton. In this case, subjects timed their responses consistent with the assumption of uniform motion in the absence of forces, even when the target actually accelerated. Overall, the results are in accord with the theory that motor responses evoked by visual kinematics are modulated by a prior of the target dynamics. The prior appears surprisingly resistant to modifications based on performance errors. PMID:14627663
A Mathematical Model to Elucidate Brain Tumor Abrogation by Immunotherapy with T11 Target Structure
Chaudhuri, Swapna
2015-01-01
T11 Target structure (T11TS), a membrane glycoprotein isolated from sheep erythrocytes, reverses the immune suppressed state of brain tumor induced animals by boosting the functional status of the immune cells. This study aims at aiding in the design of more efficacious brain tumor therapies with T11 target structure. We propose a mathematical model for brain tumor (glioma) and the immune system interactions, which aims in designing efficacious brain tumor therapy. The model encompasses considerations of the interactive dynamics of glioma cells, macrophages, cytotoxic T-lymphocytes (CD8+ T-cells), TGF-β, IFN-γ and the T11TS. The system undergoes sensitivity analysis, that determines which state variables are sensitive to the given parameters and the parameters are estimated from the published data. Computer simulations were used for model verification and validation, which highlight the importance of T11 target structure in brain tumor therapy. PMID:25955428
Integrated modeling/analyses of thermal-shock effects in SNS targets
Taleyarkhan, R.P.; Haines, J.
1996-06-01
In a spallation neutron source (SNS), extremely rapid energy pulses are introduced in target materials such as mercury, lead, tungsten, uranium, etc. Shock phenomena in such systems may possibly lead to structural material damage beyond the design basis. As expected, the progression of shock waves and interaction with surrounding materials for liquid targets can be quite different from that in solid targets. The purpose of this paper is to describe ORNL`s modeling framework for `integrated` assessment of thermal-shock issues in liquid and solid target designs. This modeling framework is being developed based upon expertise developed from past reactor safety studies, especially those related to the Advanced Neutron Source (ANS) Project. Unlike previous separate-effects modeling approaches employed (for evaluating target behavior when subjected to thermal shocks), the present approach treats the overall problem in a coupled manner using state-of-the-art equations of state for materials of interest (viz., mercury, tungsten and uranium). That is, the modeling framework simultaneously accounts for localized (and distributed) compression pressure pulse generation due to transient heat deposition, the transport of this shock wave outwards, interaction with surrounding boundaries, feedback to mercury from structures, multi-dimensional reflection patterns & stress induced (possible) breakup or fracture.
Low-Order Modeling of Micro-Flier Impact with Thin Stationary Targets
NASA Astrophysics Data System (ADS)
Fry, Mark; Gonthier, Keith
2011-06-01
The impact of high-speed (500-1500 m/s), laser driven micro-fliers with thin energetic targets (10-100 μm) is being examined to characterize impact-induced heating and combustion of these materials. To guide development of experiments, a low-order (zero-dimensional) model is formulated to estimate ballistic performance for large dimensional parameter spaces in a computationally inexpensive manner. The model accounts in a simple way for both the early time system dynamics associated with wave propagation and the late time dynamics associated with target penetration and perforation. The model is currently being validated against impact data for larger scale flier-target configurations, and is being used to give predictions for micro-scale configurations. Preliminary predictions for the impact of aluminum micro-fliers with thin steel targets indicate that the ballistic behavior is sensitive to micro-flier mass and geometry. The imaging of post-impact target coupons will be used to gain insight into deformation and failure modes, and to enhance model development. This work is funded by the AFRL-RWME, Eglin AFB, Florida.
Modeling cognitive effects on visual search for targets in cluttered backgrounds
NASA Astrophysics Data System (ADS)
Snorrason, Magnus; Ruda, Harald; Hoffman, James
1998-07-01
To understand how a human operator performs visual search in complex scenes, it is necessary to take into account top- down cognitive biases in addition to bottom-up visual saliency effects. We constructed a model to elucidate the relationship between saliency and cognitive effects in the domain of visual search for distant targets in photo- realistic images of cluttered scenes. In this domain, detecting targets is difficult and requires high visual acuity. Sufficient acuity is only available near the fixation point, i.e. in the fovea. Hence, the choice of fixation points is the most important determinant of whether targets get detected. We developed a model that predicts the 2D distribution of fixation probabilities directly from an image. Fixation probabilities were computed as a function of local contrast (saliency effect) and proximity to the horizon (cognitive effect: distant targets are more likely to be found c close to the horizon). For validation, the model's predictions were compared to ensemble statistics of subjects' actual fixation locations, collected with an eye- tracker. The model's predictions correlated well with the observed data. Disabling the horizon-proximity functionality of the model significantly degraded prediction accuracy, demonstrating that cognitive effects must be accounted for when modeling visual search.
Analytic Guided-Search Model of Human Performance Accuracy in Target- Localization Search Tasks
NASA Technical Reports Server (NTRS)
Eckstein, Miguel P.; Beutter, Brent R.; Stone, Leland S.
2000-01-01
Current models of human visual search have extended the traditional serial/parallel search dichotomy. Two successful models for predicting human visual search are the Guided Search model and the Signal Detection Theory model. Although these models are inherently different, it has been difficult to compare them because the Guided Search model is designed to predict response time, while Signal Detection Theory models are designed to predict performance accuracy. Moreover, current implementations of the Guided Search model require the use of Monte-Carlo simulations, a method that makes fitting the model's performance quantitatively to human data more computationally time consuming. We have extended the Guided Search model to predict human accuracy in target-localization search tasks. We have also developed analytic expressions that simplify simulation of the model to the evaluation of a small set of equations using only three free parameters. This new implementation and extension of the Guided Search model will enable direct quantitative comparisons with human performance in target-localization search experiments and with the predictions of Signal Detection Theory and other search accuracy models.
NASA Astrophysics Data System (ADS)
Hu, Hongtao; Jing, Zhongliang; Hu, Shiqiang
2006-12-01
A novel adaptive algorithm for tracking maneuvering targets is proposed. The algorithm is implemented with fuzzy-controlled current statistic model adaptive filtering and unscented transformation. A fuzzy system allows the filter to tune the magnitude of maximum accelerations to adapt to different target maneuvers, and unscented transformation can effectively handle nonlinear system. A bearing-only tracking scenario simulation results show the proposed algorithm has a robust advantage over a wide range of maneuvers and overcomes the shortcoming of the traditional current statistic model and adaptive filtering algorithm.
An improvement of multi-attribute decision model of grey target with interval number
NASA Astrophysics Data System (ADS)
Hu, Ming-li
2013-10-01
In view of the limits of existing decision model of grey target with interval number, a new formula for normalizing decision matrix is given based on range transformation. At the same time, on the basis of the principle of TOPSIS, a new decision model of grey target is set up considering not only the distance from positive bulls eye but also from negative one. An example is given to show the application of the method, and the results are compared with other methods. The results verify the validity and practicability of the method.
Subchannel thermal-hydraulic modeling of an APT tungsten target rod bundle
Hamm, L.L.; Shadday, M.A. Jr.
1997-09-01
The planned target for the Accelerator Production of Tritium (APT) neutron source consists of an array of tungsten rod bundles through which D{sub 2}O coolant flows axially. Here, a scoping analysis of flow through an APT target rod bundle was conducted to demonstrate that lateral cross-flows are important, and therefore subchannel modeling is necessary to accurately predict thermal-hydraulic behavior under boiling conditions. A local reactor assembly code, FLOWTRAN, was modified to model axial flow along the rod bundle as flow through three concentric heated annular passages.
Optimized model of oriented-line-target detection using vertical and horizontal filters
NASA Astrophysics Data System (ADS)
Westland, Stephen; Foster, David H.
1995-08-01
A line-element target differing sufficiently in orientation from a background of line elements can be visually detected easily and quickly; orientation thresholds for such detection are lowest when the background elements are all vertical or all horizontal. A simple quantitative model of this performance was constructed from two classes of anisotropic filters, (2) nonlinear point transformation, and (3) estimation of a signal-to-noise ratio based on responses to images with and without a target. A Monte Carlo optimization procedure (simulated annealing) was used to determine the model parameter values required for providing an accurate description of psychophysical data on orientation increment thresholds.
Characteristics of Bayesian multiple model adaptive estimation for tracking airborne targets
NASA Astrophysics Data System (ADS)
Netzer, A. S.
1985-12-01
Previous studies at the Air Force Institute of Technology have led to the development of a multiple model adaptive filter (MMAF) tracking algorithm which provides significant improvements in tracker performance against highly-dynamic airborne targets over the currently used correlation trackers. A forward looking infra-red (FLIR) sensor is used to provide a target shape function to the tracking algorithm in the form of an 8 x 8 array of intensities projected onto a field of view (FOV). This target image measurement is correlated with an estimate of the target image template, to produce linear offset pseudo-measurements from the center of the FOV, which are provided as measurements to a bank of linear Kalman filters, in the multiple model adaptive filtering (MMAF) structure. The output of the MMAF provides the state estimates used in pointing the FLIR sensor, and generating the new target image estimate. This study investigates the characteristics of this algorithm in order to evaluate its performance against various target scenarios.
Modeling and simulation method of target echo energy detection in laser simulation system
NASA Astrophysics Data System (ADS)
Cheng, Ye; Lv, Pin; Sun, Quan
2015-10-01
When using numerical simulation method study laser system, modeling and simulation energy distribution of the target echo on the detector is studied in order to achieve closed-loop optical path. From the perspective of Fresnel formula, using bidirectional reflectance distribution function (BRDF) model to calculate the intensity distribution of the target reflection; calculation of light vector angle expression reflects the phase change between reflected light and incident light when light travelling in a single medium surface. Setting position parameters and attitude parameters of different components in the laser simulation system, through the calculation of geometric relationship, the energy distribution under the view of the detector is achieved. Target surface shape was respectively set for planar, spherical and cylindrical. Analyzed the influence of targets surface roughness root mean square (RMS), zenith angle and azimuth angle of the incident light to targets reflection characteristics respectively. Results show that this method can accurately achieve the detection simulation of simple geometric shape surface target in laser system.
Threshold resummation and the determination of parton distribution functions
NASA Astrophysics Data System (ADS)
Westmark, David
Precise knowledge of parton distribution functions (PDFs) is necessary to the accurate calculation of QCD observables initiated by hadrons. The deep inelastic scattering (DIS) and lepton pair production (LPP) processes are primary sources of information on PDFs. Recent global fits for PDFs have used DIS data from the large Bjorken x, moderate Q 2 region. It is known that there are large logarithms in this kinematic region that can be resummed using threshold resummation techniques. The purpose of this study is to investigate the effects of simultaneously including DIS and LPP threshold resummation in the determinations of PDFs. The analysis includes a study of the effects of the choice of resummation prescription and of current resummation methods used in the LPP rapidity and x F distributions. It is demonstrated theoretically and phenomenologically that the current resummation methods for such distributions are approximations that lose accuracy at high rapidities or xF. The unapproximated resummation formalism is extended to the MS scheme in the minimal and Borel prescriptions and used in conjunction with resummation in DIS to perform a global fit. The resultant PDF sets that correspond to two choices of resummation prescription are analyzed to determine the effect of threshold resummation on PDF fits and its theoretical uncertainties.
Energy flow along the medium-induced parton cascade
NASA Astrophysics Data System (ADS)
Blaizot, J.-P.; Mehtar-Tani, Y.
2016-05-01
We discuss the dynamics of parton cascades that develop in dense QCD matter, and contrast their properties with those of similar cascades of gluon radiation in vacuum. We argue that such cascades belong to two distinct classes that are characterized respectively by an increasing or a constant (or decreasing) branching rate along the cascade. In the former class, of which the BDMPS, medium-induced, cascade constitutes a typical example, it takes a finite time to transport a finite amount of energy to very soft quanta, while this time is essentially infinite in the latter case, to which the DGLAP cascade belongs. The medium induced cascade is accompanied by a constant flow of energy towards arbitrary soft modes, leading eventually to the accumulation of the initial energy of the leading particle at zero energy. It also exhibits scaling properties akin to wave turbulence. These properties do not show up in the cascade that develops in vacuum. There, the energy accumulates in the spectrum at smaller and smaller energy as the cascade develops, but the energy never flows all the way down to zero energy. Our analysis suggests that the way the energy is shared among the offsprings of a splitting gluon has little impact on the qualitative properties of the cascades, provided the kernel that governs the splittings is not too singular.
Deeply virtual Compton scattering and generalized parton distributions at CLAS
Niccolai, Silvia
2008-11-01
The exclusive electroproduction of real photons and mesons at high momentum transfer allows us to access the Generalized Parton Distributions (GPDs). The formalism of the GPDs provides a unified description of the hadronic structure in terms of quark and gluonic degrees of freedom. In particular, the Deeply Virtual Compton Scattering (DVCS), ep â e2p2Å , is one of the key reactions to determine the GPDs experimentally, as it is the simplest process that can be described in terms of GPDs. A dedicated experiment to study DVCS has been carried out in Hall B at Jefferson Lab. Beam-spin asymmetries, resulting from the interference of the Bethe-Heitler process and DVCS have been extracted over the widest kinematic range ever accessed for this reaction ( 1.2 < Q 2 < 3.7 (GeV/c 2, 0.09 < - t < 1.3 (GeV/c 2, 0.13 < x B < 0.46 . In this paper, the results obtained experimentally are shown and compared to GPD parametrizations.
Modeling human target acquisition in ground-to-air weapon systems
NASA Technical Reports Server (NTRS)
Phatak, A. V.; Mohr, R. L.; Vikmanis, M.; Wei, K. C.
1982-01-01
The problems associated with formulating and validating mathematical models for describing and predicting human target acquisition response are considered. In particular, the extension of the human observer model to include the acquisition phase as well as the tracking segment is presented. Relationship of the Observer model structure to the more complex Standard Optimal Control model formulation and to the simpler Transfer Function/Noise representation is discussed. Problems pertinent to structural identifiability and the form of the parameterization are elucidated. A systematic approach toward the identification of the observer acquisition model parameters from ensemble tracking error data is presented.
Lineweaver, Charles H.; Davies, Paul C.W.; Vincent, Mark D.
2014-01-01
In the atavistic model of cancer progression, tumor cell dedifferentiation is interpreted as a reversion to phylogenetically earlier capabilities. The more recently evolved capabilities are compromised first during cancer progression. This suggests a therapeutic strategy for targeting cancer: design challenges to cancer that can only be met by the recently evolved capabilities no longer functional in cancer cells. We describe several examples of this target-the-weakness strategy. Our most detailed example involves the immune system. The absence of adaptive immunity in immunosuppressed tumor environments is an irreversible weakness of cancer that can be exploited by creating a challenge that only the presence of adaptive immunity can meet. This leaves tumor cells more vulnerable than healthy tissue to pathogenic attack. Such a target-the-weakness therapeutic strategy has broad applications, and contrasts with current therapies that target the main strength of cancer: cell proliferation. PMID:25043755
The analytic model of a laser-accelerated plasma target and its stability
Khudik, V. Yi, S. A.; Siemon, C.; Shvets, G.
2014-01-15
A self-consistent kinetic theory of a laser-accelerated plasma target with distributed electron/ion densities is developed. The simplified model assumes that after an initial transition period the bulk of cold ions are uniformly accelerated by the self-consistent electric field generated by hot electrons trapped in combined ponderomotive and electrostatic potentials. Several distinct target regions (non-neutral ion tail, non-neutral electron sheath, and neutral plasma bulk) are identified and analytically described. It is shown analytically that such laser-accelerated finite-thickness target is susceptible to Rayleigh-Taylor (RT) instability. Particle-in-cell simulations of the seeded perturbations of the plasma target reveal that, for ultra-relativistic laser intensities, the growth rate of the RT instability is depressed from the analytic estimates.
Validation of a target acquisition model for active imager using perception experiments
NASA Astrophysics Data System (ADS)
Lapaz, Frédéric; Canevet, Loïc
2007-10-01
Active night vision systems based on laser diodes emitters have now reached a technology level allowing military applications. In order to predict the performance of observers using such systems, we built an analytic model including sensor, atmosphere, visualization and eye effects. The perception task has been modelled using the Targeting Task Performance metric (TTP metric) developed by R. Vollmerhausen from the Night Vision and Electronic Sensors Directorate (NVESD). Sensor and atmosphere models have been validated separately. In order to validate the whole model, two identification tests have been set up. The first set submitted to trained observers was made of hybrid images. The target to background contrast, the blur and the noise were added to armoured vehicles signatures in accordance to sensor and atmosphere models. The second set of images was made with the same targets, sensed by a real active sensor during field trials. Images were recorded, showing different vehicles, at different ranges and orientations, under different illumination and acquisition configurations. Indeed, this set of real images was built with three different types of gating: wide illumination, illumination of the background and illumination of the target. Analysis of the perception experiments results showed a good concordance between the two sets of images. The calculation of an identification criterion, related to this set of vehicles in the near infrared, gave the same results in both cases. The impact of gating on observer's performance was also evaluated.
Vapor shielding models and the energy absorbed by divertor targets during transient events
NASA Astrophysics Data System (ADS)
Skovorodin, D. I.; Pshenov, A. A.; Arakcheev, A. S.; Eksaeva, E. A.; Marenkov, E. D.; Krasheninnikov, S. I.
2016-02-01
The erosion of divertor targets caused by high heat fluxes during transients is a serious threat to ITER operation, as it is going to be the main factor determining the divertor lifetime. Under the influence of extreme heat fluxes, the surface temperature of plasma facing components can reach some certain threshold, leading to an onset of intense material evaporation. The latter results in formation of cold dense vapor and secondary plasma cloud. This layer effectively absorbs the energy of the incident plasma flow, turning it into its own kinetic and internal energy and radiating it. This so called vapor shielding is a phenomenon that may help mitigating the erosion during transient events. In particular, the vapor shielding results in saturation of energy (per unit surface area) accumulated by the target during single pulse of heat load at some level Emax. Matching this value is one of the possible tests to verify complicated numerical codes, developed to calculate the erosion rate during abnormal events in tokamaks. The paper presents three very different models of vapor shielding, demonstrating that Emax depends strongly on the heat pulse duration, thermodynamic properties, and evaporation energy of the irradiated target material. While its dependence on the other shielding details such as radiation capabilities of material and dynamics of the vapor cloud is logarithmically weak. The reason for this is a strong (exponential) dependence of the target material evaporation rate, and therefore the "strength" of vapor shield on the target surface temperature. As a result, the influence of the vapor shielding phenomena details, such as radiation transport in the vapor cloud and evaporated material dynamics, on the Emax is virtually completely masked by the strong dependence of the evaporation rate on the target surface temperature. However, the very same details define the amount of evaporated particles, needed to provide an effective shielding to the target, and
NASA Astrophysics Data System (ADS)
Thajudeen, Christopher; Hoorfar, Ahmad; Ahmad, Fauzia; Dogaru, Traian
2010-04-01
With recent advances in both algorithm and component technologies, through-the-wall sensing and imaging is emerging as an affordable sensor technology in civilian and military settings. One of the primary objectives of through-the-wall sensing systems is to detect and identify targets of interest, such as humans and cache of weapons, enclosed in building structures. Effective approaches that achieve proper target radar cross section (RCS) registration behind walls must, in general, exploit a detailed understanding of the radar phenomenology and more specifically, knowledge of the expected strength of the radar return from targets of interest. In this paper, we investigate the effects of various wall types on the received power of the target return through the use of a combined measurement and electromagnetic modeling approach. The RCS of material-exact rifle and human models are investigated in free-space using numerical electromagnetic modeling tools. A modified radar range equation, which analytically accounts for the wall effects, including multiple reflections within a given homogeneous or layered wall, is then employed in conjunction with wideband measured parameters of various common wall types, to estimate the received power versus frequency from the aforementioned targets. The proposed technique is, in principle, applicable to both bistatic and mono-static operations.
Numerical modeling for energy transport and isochoric heating in ultra-fast heated high Z target
NASA Astrophysics Data System (ADS)
Mishra, Rohini; Sentoku, Yasuhiko; Hakel, Peter; Mancini, Roberto C.
2010-11-01
Collisional Particle-in-Cell (PIC) code is an effective tool to study extreme energy density conditions achieved in intense laser-solid interactions. In the continuous process of developing PIC code, we have recently implemented models to incorporate dynamic ionizations, namely Saha and Thomas Fermi, and radiation cooling (due to Bremsstrahlung and line emissions). We have also revised the existing collision model to take into account bounded electrons in dynamically ionizing target (partially ionized target). One-dimensional PIC simulation of a gold target with new collision model shows strong local heating in a micron distance due to shorter stopping range of fast electrons, which reflects the increased collision frequency due to bound electrons. The peak temperature in the heated region drops significantly due to the radiation cooling to a level of a few hundred eV from keV. We also discuss the target Z dependence on radiation loss and two-dimensional effects such as the resistive magnetic fields in the hot electron transport in metal targets.
An Analytic Model for the Success Rate of a Robotic Actuator System in Hitting Random Targets
Bradley, Stuart
2015-01-01
Autonomous robotic systems are increasingly being used in a wide range of applications such as precision agriculture, medicine, and the military. These systems have common features which often includes an action by an “actuator” interacting with a target. While simulations and measurements exist for the success rate of hitting targets by some systems, there is a dearth of analytic models which can give insight into, and guidance on optimization, of new robotic systems. The present paper develops a simple model for estimation of the success rate for hitting random targets from a moving platform. The model has two main dimensionless parameters: the ratio of actuator spacing to target diameter; and the ratio of platform distance moved (between actuator “firings”) to the target diameter. It is found that regions of parameter space having specified high success are described by simple equations, providing guidance on design. The role of a “cost function” is introduced which, when minimized, provides optimization of design, operating, and risk mitigation costs. PMID:26610500
A model for forming airborne synthetic aperture radar images of underground targets
Doerry, A.W.
1994-01-01
Synthetic Aperture Radar (SAR) from an airborne platform has been proposed for imaging targets beneath the earth`s surface. The propagation of the radar`s energy within the ground, however, is much different than in the earth`s atmosphere. The result is signal refraction, echo delay, propagation losses, dispersion, and volumetric scattering. These all combine to make SAR image formation from an airborne platform much more challenging than a surface imaging counterpart. This report treats the ground as a lossy dispersive half-space, and presents a model for the radar echo based on measurable parameters. The model is then used to explore various imaging schemes, and image properties. Dynamic range is discussed, as is the impact of loss on dynamic range. Modified window functions are proposed to mitigate effects of sidelobes of shallow targets overwhelming deeper targets.
A model for combined targeting and tracking tasks in computer applications.
Senanayake, Ransalu; Hoffmann, Errol R; Goonetilleke, Ravindra S
2013-11-01
Current models for targeted-tracking are discussed and shown to be inadequate as a means of understanding the combined task of tracking, as in the Drury's paradigm, and having a final target to be aimed at, as in the Fitts' paradigm. It is shown that the task has to be split into components that are, in general, performed sequentially and have a movement time component dependent on the difficulty of the individual component of the task. In some cases, the task time may be controlled by the Fitts' task difficulty, and in others, it may be dominated by the Drury's task difficulty. Based on an experiment carried out that captured movement time in combinations of visually controlled and ballistic movements, a model for movement time in targeted-tracking was developed. PMID:24081679
Empirical modeling of renal motion for improved targeting during focused ultrasound surgery.
Abhilash, R H; Chauhan, Sunita
2013-05-01
Non-invasive surgery looks at ways of eliminating physical contact with the target tissues while maintaining necessary levels of accuracy. Focused Ultrasound Surgery (FUS) is one such treatment modality, which uses a tightly focused beam of high intensity ultrasound to ablate tumors in various parts of the body. For trans-abdominal access, respiration induced movement of the tissue targets remains a major issue during FUS. Respiration induced movements are known to be significant in liver and kidney. In this paper, we attempt to address this problem using non-linear prediction and modeling techniques as applicable to kidney movement patterns. Kidney movement patterns are known to be three dimensional and vastly complicated compared to movement patterns of the liver. Monitoring and quantification of the nature and extent of kidney movement is yet to be explored in depth for effective compensation and accurate targeting. Apart from the respiratory cycle, the movement of the kidney is also affected by several factors, such as the movement of the ribs, spleen and liver. Modeling of these movements is imperative for motion adaptive FUS. Since kidney movements are highly subject specific, generic statistical models cannot be used for compensation. The system latency and real-time performance of the imaging modality also induce additional parametric dependence in target tracking. In this work, we focus on empirical modeling and prediction of the kidney movement to for error analysis and computing system latency. The accuracy of existing modeling techniques is compared with a newly developed empirical model. From the study conducted in healthy volunteers, it was found that the kidney movement was complex and subject specific and could be effectively modeled using the new shape function based model. The model was further fine-tuned using Kalman filter based predictors and Adaptive Neuro-Fuzzy Inference System (ANFIS) which gave more than 85% accuracy in prediction. PMID
Comparison of Different INC Physical Models of MCNPX to Compute Spallation Neutronics of LBE Target
NASA Astrophysics Data System (ADS)
Feghhi, Seyed Amir Hossein; Gholamzadeh, Zohreh; Tenreiro, Claudio; Alipoor, Zahra
2015-04-01
Spallation particles can utilize in different fields such as neutron scattering studies, external source for burning spent fuel as well as running subcritical reactors. Different computational particle transport codes are widely used to model spallation process into the heavy targets. Among these codes, MCNPX 2.6.0 comprises various intra nuclear cascade models for spallation calculations. Impact of different intra nuclear cascade models on calculation of neutronic parameters of LBE target has been evaluated in this work. Escaped neutron yield, energy deposition and residual nuclei production in the spallation target has been calculated using the physical models. A comparison between the computational and experimental has been carried out to validate the computational data. The simulation data showed there is a good conformity between the obtained data from Bertini/Drenser and Isabel/Drenser. The data achieved by Bertini/Abla and Isabel/Abla models are close to each other for the studied parameters as well. Among the studied models, CEM showed more discrepancies with experimental and other computational data. According to the obtained data, INCL4/Drenser, INCL4/Abla and Isabel/Drenser models can meet more agreements with experimental data.
Computational Modeling of Tumor Response to Vascular-Targeting Therapies—Part I: Validation
Gevertz, Jana L.
2011-01-01
Mathematical modeling techniques have been widely employed to understand how cancer grows, and, more recently, such approaches have been used to understand how cancer can be controlled. In this manuscript, a previously validated hybrid cellular automaton model of tumor growth in a vascularized environment is used to study the antitumor activity of several vascular-targeting compounds of known efficacy. In particular, this model is used to test the antitumor activity of a clinically used angiogenesis inhibitor (both in isolation, and with a cytotoxic chemotherapeutic) and a vascular disrupting agent currently undergoing clinical trial testing. I demonstrate that the mathematical model can make predictions in agreement with preclinical/clinical data and can also be used to gain more insight into these treatment protocols. The results presented herein suggest that vascular-targeting agents, as currently administered, cannot lead to cancer eradication, although a highly efficacious agent may lead to long-term cancer control. PMID:21461361
Reaction dynamics of {sup 34-38}Mg projectile with carbon target using Glauber model
Shama, Mahesh K.; Panda, R. N.; Sharma, Manoj K.; Patra, S. K.
2015-08-28
We have studied nuclear reaction cross-sections for {sup 34-38}Mg isotopes as projectile with {sup 12}C target at projectile energy 240AMeV using Glauber model with the conjunction of densities from relativistic mean filed formalism. We found good agreement with the available experimental data. The halo status of {sup 37}Mg is also investigated.
ERIC Educational Resources Information Center
Zhang, Mo; Williamson, David M.; Breyer, F. Jay; Trapani, Catherine
2012-01-01
This article describes two separate, related studies that provide insight into the effectiveness of "e-rater" score calibration methods based on different distributional targets. In the first study, we developed and evaluated a new type of "e-rater" scoring model that was cost-effective and applicable under conditions of absent human rating and…
TARGETED DELIVERY OF INHALED PHARMACEUTICALS USING AN IN SILICO DOSIMETRY MODEL
We present an in silico dosimetry model which can be used for inhalation toxicology (risk assessment of inhaled air pollutants) and aerosol therapy ( targeted delivery of inhaled drugs). This work presents scientific and clinical advances beyond the development of the original in...
NASA Astrophysics Data System (ADS)
Sinenian, N.; J-E Manuel, M.; Frenje, J. A.; Séguin, F. H.; Li, C. K.; Petrasso, R. D.
2013-04-01
Charging of inertial confinement fusion (ICF) targets generates a potential well that traps energetic electrons within the target. Trapped electrons can preheat the fuel, raise the adiabat, degrade compression and perhaps have an effect on achieving the high areal densities (ρR) required for ignition and gain. The decay time of this potential is thus an important parameter for any calculations of preheat. A nonlinear model of electrical discharging of ICF capsules has been developed and is presented here. The empirical model, which captures the essential dynamics of the target voltage decay, incorporates previous charged-particle spectroscopic and radiographic measurements of the fields surrounding the target. On the basis of this model, it is shown that the decay time is weakly dependent on the initial voltage of the target. In addition, it is shown that currents through the target support fiber aid target discharging. Implications of these findings for inertial fusion energy targets without support fibers are discussed.
Target identification and navigation performance modeling of a passive millimeter wave imager.
Jacobs, Eddie L; Furxhi, Orges
2010-07-01
Human task performance using a passive interferometric millimeter wave imaging sensor is modeled using a task performance modeling approach developed by the U.S. Army Night Vision and Electronic Sensors Directorate. The techniques used are illustrated for an imaging system composed of an interferometric antenna array, optical upconversion, and image formation using a shortwave infrared focal plane array. Two tasks, target identification and pilotage, are modeled. The effects of sparse antenna arrays on task performance are considered. Applications of this model include system trade studies for concealed weapon identification, navigation in fog, and brownout conditions. PMID:20648126
Simulation-based sensor modeling and at-range target detection characterization with MuSES
NASA Astrophysics Data System (ADS)
Packard, Corey D.; Curran, Allen R.; Saur, Nicholas E.; Rynes, Peter L.
2015-05-01
Accurate infrared signature prediction of targets, such as humans or ground vehicles, depends primarily on the realistic prediction of physical temperatures. Thermal model development typically requires a geometric description of the target (i.e., a 3D surface mesh) along with material properties for characterizing the thermal response to simulated weather conditions. Once an accurate thermal solution has been obtained, signature predictions for an EO/IR spectral waveband can be generated. The image rendering algorithm should consider the radiative emissions, diffuse/specular reflections, and atmospheric effects to depict how an object in a natural scene would be perceived by an EO/IR sensor. The EO/IR rendering process within MuSES, developed by ThermoAnalytics, can be used to create a synthetic radiance image that predicts the energy detected by a specific sensor just prior to passing through its optics. For additional realism, blurring due to lens diffraction and noise due to variations in photon detection can also be included, via specification of sensor characteristics. Additionally, probability of detection can be obtained via the Targeting Task Performance (TTP) metric, making it possible to predict a target's at-range detectability to a particular threat sensor. In this paper, we will investigate the at-range contrast and detectability of some example targets and examine the effect of various techniques such as sub-pixel sampling and target pixel thresholding.
Fragment Impact Toolkit: A Toolkit for Modeling Fragment Generation and Impacts on Targets
NASA Astrophysics Data System (ADS)
Shevitz, Daniel
2005-07-01
In this talk we will detail the status of the Fragment Impact Toolkit. The toolkit is used to model nearby explosion problems and assess probabilities of user-specified outcomes. The toolkit offers a framework, without locking the user into any particular set of states, assumptions, or constraints. The toolkit breaks a fragment impact problem into five components, all of which are extendable: (1) source description that includes the geometry of the source; (2) fragment generation that comprises the fragmentation process, including fragment size distributions (if required) and assignment of initial conditions, such a velocity; (3) fragment flight that includes what occurs to fragments while airborne; (4) target intersection that includes specification of target geometry, position, and orientation; and (5) target consequence that includes what occurs when fragments hit a target. Two notable contributions of the toolkit are the ability to have sources that break up with position-dependent and user-specifiable size probability distributions and then impact targets of arbitrary complexity. In this paper we will show examples of how to use the toolkit and simulate targets, including airplanes and stacks of munitions.
NASA Astrophysics Data System (ADS)
Xing, Rui; Chen, Xue-Dong; Zhou, Yan-Feng; Zhang, Jue; Su, Yuan-Yuan; Qiu, Jian-Feng; Sima, Yang-Hu; Zhang, Ke-Qin; He, Yao; Xu, Shi-Qing
2016-01-01
The use of quantum dots (QDs) in biological imaging applications and targeted drug delivery is expected to increase. However, the efficiency of QDs in drug targeting needs to be improved. Here, we show that amino acids linked to CdTe QDs significantly increased the targeted transfer efficiency and biological safety in the invertebrate model Bombyx mori. Compared with bare QDs530, the transfer efficiency of Ala- and Gly-conjugated QDs (QDs530-Ala and QDs530-Gly) in circulatory system increased by 2.6 ± 0.3 and 1.5 ± 0.3 times, and increased by 7.8 ± 0.9 and 2.9 ± 0.2 times in target tissue silk glands, respectively, after 24 h of QDs exposure. Meanwhile, the amount of conjugated QDs decreased by (68.4 ± 4.4)% and (46.7 ± 9.1)% in the non-target tissue fat body, and the speed at which they entered non-target circulating blood cells significantly decreased. The resultant QDs530-Ala revealed a better structural integrity in tissues and a longer retention time in hemolymph than that of QDs530 after exposure via the dorsal vessel. On the other hand, QDs530-Ala significantly reduced the toxicity to hemocytes, silk gland, and fat body, and reduced the amount of reactive oxygen species (ROS) in tissues.
Zhu, Peican; Aliabadi, Hamidreza Montazeri; Uludağ, Hasan; Han, Jie
2016-01-01
The investigation of vulnerable components in a signaling pathway can contribute to development of drug therapy addressing aberrations in that pathway. Here, an original signaling pathway is derived from the published literature on breast cancer models. New stochastic logical models are then developed to analyze the vulnerability of the components in multiple signalling sub-pathways involved in this signaling cascade. The computational results are consistent with the experimental results, where the selected proteins were silenced using specific siRNAs and the viability of the cells were analyzed 72 hours after silencing. The genes elF4E and NFkB are found to have nearly no effect on the relative cell viability and the genes JAK2, Stat3, S6K, JUN, FOS, Myc, and Mcl1 are effective candidates to influence the relative cell growth. The vulnerabilities of some targets such as Myc and S6K are found to vary significantly depending on the weights of the sub-pathways; this will be indicative of the chosen target to require customization for therapy. When these targets are utilized, the response of breast cancers from different patients will be highly variable because of the known heterogeneities in signaling pathways among the patients. The targets whose vulnerabilities are invariably high might be more universally acceptable targets. PMID:26988076
Early recognition of lung cancer by integrin targeted imaging in K-ras mouse model.
Ermolayev, Vladimir; Mohajerani, Pouyan; Ale, Angelique; Sarantopoulos, Athanasios; Aichler, Michaela; Kayser, Gian; Walch, Axel; Ntziachristos, Vasilis
2015-09-01
Non-small cell lung cancer is characterized by slow progression and high heterogeneity of tumors. Integrins play an important role in lung cancer development and metastasis and were suggested as a tumor marker; however their role in anticancer therapy remains controversial. In this work, we demonstrate the potential of integrin-targeted imaging to recognize early lesions in transgenic mouse model of lung cancer based on spontaneous introduction of mutated human gene bearing K-ras mutation. We conducted ex vivo and fluorescence molecular tomography-X-ray computed tomography (FMT-XCT) in vivo imaging and analysis for specific targeting of early lung lesions and tumors in rodent preclinical model for lung cancer. The lesions and tumors were characterized by histology, immunofluorescence and immunohistochemistry using a panel of cancer markers. Ex vivo, the integrin-targeted fluorescent signal significantly differed between wild type lung tissue and K-ras pulmonary lesions (PL) at all ages studied. The panel of immunofluorescence experiments demonstrated that PL, which only partially show cancer cell features were detected by αvβ3-integrin targeted imaging. Human patient material analysis confirmed the specificity of target localization in different lung cancer types. Most importantly, small tumors in the lungs of 4-week-old animals could be noninvasively detected in vivo on the fluorescence channel of FMT-XCT. Our findings demonstrated αvβ3-integrin targeted fluorescent imaging to specifically detect premalignant pleural lesions in K-ras mice. Integrin targeted imaging may find application areas in preclinical research and clinical practice, such as early lung cancer diagnostics, intraoperative assistance or therapy monitoring. PMID:25450481
From drug response profiling to target addiction scoring in cancer cell models.
Yadav, Bhagwan; Gopalacharyulu, Peddinti; Pemovska, Tea; Khan, Suleiman A; Szwajda, Agnieszka; Tang, Jing; Wennerberg, Krister; Aittokallio, Tero
2015-10-01
Deconvoluting the molecular target signals behind observed drug response phenotypes is an important part of phenotype-based drug discovery and repurposing efforts. We demonstrate here how our network-based deconvolution approach, named target addiction score (TAS), provides insights into the functional importance of druggable protein targets in cell-based drug sensitivity testing experiments. Using cancer cell line profiling data sets, we constructed a functional classification across 107 cancer cell models, based on their common and unique target addiction signatures. The pan-cancer addiction correlations could not be explained by the tissue of origin, and only correlated in part with molecular and genomic signatures of the heterogeneous cancer cells. The TAS-based cancer cell classification was also shown to be robust to drug response data resampling, as well as predictive of the transcriptomic patterns in an independent set of cancer cells that shared similar addiction signatures with the 107 cancers. The critical protein targets identified by the integrated approach were also shown to have clinically relevant mutation frequencies in patients with various cancer subtypes, including not only well-established pan-cancer genes, such as PTEN tumor suppressor, but also a number of targets that are less frequently mutated in specific cancer types, including ABL1 oncoprotein in acute myeloid leukemia. An application to leukemia patient primary cell models demonstrated how the target deconvolution approach offers functional insights into patient-specific addiction patterns, such as those indicative of their receptor-type tyrosine-protein kinase FLT3 internal tandem duplication (FLT3-ITD) status and co-addiction partners, which may lead to clinically actionable, personalized drug treatment developments. To promote its application to the future drug testing studies, we have made available an open-source implementation of the TAS calculation in the form of a stand-alone R
Biochemical pathway modeling tools for drug target detection in cancer and other complex diseases.
Marin-Sanguino, Alberto; Gupta, Shailendra K; Voit, Eberhard O; Vera, Julio
2011-01-01
In the near future, computational tools and methods based on the mathematical modeling of biomedically relevant networks and pathways will be necessary for the design of therapeutic strategies that fight complex multifactorial diseases. Beyond the use of pharmacokinetic and pharmacodynamic approaches, we propose here the use of dynamic modeling as a tool for describing and analyzing the structure and responses of signaling, genetic and metabolic networks involved in such diseases. Specifically, we discuss the design and construction of meaningful models of biochemical networks, as well as tools, concepts, and strategies for using these models in the search of potential drug targets. We describe three different families of computational tools: predictive model simulations as tools for designing optimal drug profiles and doses; sensitivity analysis as a method to detect key interactions that affect critical outcomes and other characteristics of the network; and other tools integrating mathematical modeling with advanced computation and optimization for detecting potential drug targets. Furthermore, we show how potential drug targets detected with these approaches can be used in a computer-aided context to design or select new drug molecules. All concepts are illustrated with simplified examples and with actual case studies extracted from the recent literature. PMID:21187230
Optimal Strategies for Controlling Riverine Tsetse Flies Using Targets: A Modelling Study
Vale, Glyn A.; Hargrove, John W.; Lehane, Michael J.; Solano, Philippe; Torr, Stephen J.
2015-01-01
Background Tsetse flies occur in much of sub-Saharan Africa where they transmit the trypanosomes that cause the diseases of sleeping sickness in humans and nagana in livestock. One of the most economical and effective methods of tsetse control is the use of insecticide-treated screens, called targets, that simulate hosts. Targets have been ~1m2, but recently it was shown that those tsetse that occupy riverine situations, and which are the main vectors of sleeping sickness, respond well to targets only ~0.06m2. The cheapness of these tiny targets suggests the need to reconsider what intensity and duration of target deployments comprise the most cost-effective strategy in various riverine habitats. Methodology/Principal Findings A deterministic model, written in Excel spreadsheets and managed by Visual Basic for Applications, simulated the births, deaths and movement of tsetse confined to a strip of riverine vegetation composed of segments of habitat in which the tsetse population was either self-sustaining, or not sustainable unless supplemented by immigrants. Results suggested that in many situations the use of tiny targets at high density for just a few months per year would be the most cost-effective strategy for rapidly reducing tsetse densities by the ~90% expected to have a great impact on the incidence of sleeping sickness. Local elimination of tsetse becomes feasible when targets are deployed in isolated situations, or where the only invasion occurs from populations that are not self-sustaining. Conclusion/Significance Seasonal use of tiny targets deserves field trials. The ability to recognise habitat that contains tsetse populations which are not self-sustaining could improve the planning of all methods of tsetse control, against any species, in riverine, savannah or forest situations. Criteria to assist such recognition are suggested. PMID:25803871
Modeling and dynamic performance evaluation of target capture in robotic systems
Koevecses, J.; Cleghorn, W.L.; Fenton, R.G.
2000-04-01
In this paper, a dynamic system consisting of a robot manipulator and a target is analyzed. The target is considered in a general way as a dynamic subsystem having finite mass and moments of inertia (e.g., a rigid body or a second robot). The situation investigated is when the robot establishes interaction with the target in such a way that it intercepts and captures a reference element of the target. The analysis of target capture is divided into three phases in terms of time: the precapture, free motion (finite motion); the transition from free to constrained motion in the vicinity of interception and capture (impulsive motion); and the postcapture, constrained motion (finite motion). The greatest attention is paid to the analysis of the phase of transition, the impulsive motion, and dynamics of the system. Based on the use of impulsive constraints and the Jourdainian formulation of analytical dynamics, a novel approach is proposed for the dynamic modeling of target capture by a robot manipulator. The proposed approach is suitable to handle both finite and impulsive motions in a common analytical framework. Based on the dynamic model developed and using a geometric representation of the system's dynamics, a detailed analysis and a performance evaluation framework are presented for the phase of transition. Both rigid and structurally flexible models of robots are considered. For the performance evaluation analyses, two main concepts are proposed and corresponding performance measures are derived. These tools may be used in the analysis, design, and control of time-varying robotic systems. The dynamic system of a three-link robot arm capturing a rigid body is used to illustrate the material presented.
Dynamical next-to-next-to-leading order parton distributions
Jimenez-Delgado, P.; Reya, E.
2009-04-01
Utilizing recent deep inelastic scattering measurements ({sigma}{sub r},F{sub 2,3,L}) and data on hadronic dilepton production we determine at next-to-next-to-leading order (NNLO) (3-loop) of QCD the dynamical parton distributions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale (Q{sub 0}{sup 2}<1 GeV{sup 2}). These are compared with 'standard' NNLO distributions generated from positive input distributions at some fixed and higher resolution scale (Q{sub 0}{sup 2}>1 GeV{sup 2}). Although the NNLO corrections imply in both approaches an improved value of {chi}{sup 2}, typically {chi}{sub NNLO}{sup 2}{approx_equal}0.9{chi}{sub NLO}{sup 2}, present deep inelastic scattering data are still not sufficiently accurate to distinguish between NLO results and the minute NNLO effects of a few percent, despite the fact that the dynamical NNLO uncertainties are somewhat smaller than the NLO ones and both are, as expected, smaller than those of their standard counterparts. The dynamical predictions for F{sub L}(x,Q{sup 2}) become perturbatively stable already at Q{sup 2}=2-3 GeV{sup 2} where precision measurements could even delineate NNLO effects in the very small-x region. This is in contrast to the common standard approach but NNLO/NLO differences are here less distinguishable due to the larger 1{sigma} uncertainty bands. Within the dynamical approach we obtain {alpha}{sub s}(M{sub Z}{sup 2})=0.1124{+-}0.0020, whereas the somewhat less constrained standard fit gives {alpha}{sub s}(M{sub Z}{sup 2})=0.1158{+-}0.0035.
A Production System Model of Capturing Reactive Moving Targets. M.S. Thesis
NASA Technical Reports Server (NTRS)
Jagacinski, R. J.; Plamondon, B. D.; Miller, R. A.
1984-01-01
Subjects manipulated a control stick to position a cursor over a moving target that reacted with a computer-generated escape strategy. The cursor movements were described at two levels of abstraction. At the upper level, a production system described transitions among four modes of activity; rapid acquisition, close following, a predictive mode, and herding. Within each mode, differential equations described trajectory-generating mechanisms. A simulation of this two-level model captures the targets in a manner resembling the episodic time histories of human subjects.
Analytical model for interaction of short intense laser pulse with solid target
Luan, S. X.; Ma, G. J.; Yu, Wei; Yu, M. Y.; Zhang, Q. J.; Sheng, Z. M.; Murakami, M.
2011-04-15
A simple but comprehensive two-dimensional analytical model for the interaction of a normally incident short intense laser pulse with a solid-density plasma is proposed. Electron cavitation near the target surface by the laser ponderomotive force induces a strong local electrostatic charge-separation field. The cavitation makes possible mode conversion of the laser light into longitudinal electron oscillation at laser frequency, even for initial normal incidence of laser pulse. The intense charge-separation field in the cavity can significantly enhance the laser induced uxB electron oscillation at twice laser frequency to density levels even higher than that of the initial target.
Pisano, S.; Biselli, A.; Niccolai, S.; Seder, E.; Guidal, M.; Mirazita, M.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bosted, P.; Briscoe, B.; Brock, J.; Brooks, W. K.; Burkert, V. D.; Carlin, C.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crabb, D. G.; Crede, V.; D' Angelo, A.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garcon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hanretty, C.; Hattawy, M.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, X.; Jo, H. S.; Joo, K.; Joosten, S.; Keith, C. D.; Keller, D.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacCormick, M.; MacGregor, Ian J. D.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Meyer, C. A.; Mokeev, V.; Montgomery, R. A.; Moody, C. I.; Munoz Camacho, C.; Nadel-Turonski, P.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Phelps, W.; Phillips, J. J.; Pogorelko, O.; Price, J. W.; Procureur, S.; Prok, Y.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatie, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Skorodumina, I.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strauch, S.; Sytnik, V.; Tian, Ye; Tkachenko, S.; Turisini, M.; Ungaro, M.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.
2015-03-19
Single-beam, single-target, and double-spin asymmetries for hard exclusive photon production on the proton e→p→e'p'γ are presented. The data were taken at Jefferson Lab using the CLAS detector and a longitudinally polarized ^{14}NH_{3} target. The three asymmetries were measured in 165 4-dimensional kinematic bins, covering the widest kinematic range ever explored simultaneously for beam and target-polarization observables in the valence quark region. The kinematic dependences of the obtained asymmetries are discussed and compared to the predictions of models of Generalized Parton Distributions. As a result, the measurement of three DVCS spin observables at the same kinematic points allows a quasi-model-independent extraction of the imaginary parts of the H and H~ Compton Form Factors, which give insight into the electric and axial charge distributions of valence quarks in the proton.
Interacting multiple model forward filtering and backward smoothing for maneuvering target tracking
NASA Astrophysics Data System (ADS)
Nandakumaran, N.; Sutharsan, S.; Tharmarasa, R.; Lang, Tom; McDonald, Mike; Kirubarajan, T.
2009-08-01
The Interacting Multiple Model (IMM) estimator has been proven to be effective in tracking agile targets. Smoothing or retrodiction, which uses measurements beyond the current estimation time, provides better estimates of target states. Various methods have been proposed for multiple model smoothing in the literature. In this paper, a new smoothing method, which involves forward filtering followed by backward smoothing while maintaining the fundamental spirit of the IMM, is proposed. The forward filtering is performed using the standard IMM recursion, while the backward smoothing is performed using a novel interacting smoothing recursion. This backward recursion mimics the IMM estimator in the backward direction, where each mode conditioned smoother uses standard Kalman smoothing recursion. Resulting algorithm provides improved but delayed estimates of target states. Simulation studies are performed to demonstrate the improved performance with a maneuvering target scenario. The comparison with existing methods confirms the improved smoothing accuracy. This improvement results from avoiding the augmented state vector used by other algorithms. In addition, the new technique to account for model switching in smoothing is a key in improving the performance.
Modeling and production of 240Am by deuteron-induced activation of a 240Pu target
NASA Astrophysics Data System (ADS)
Finn, Erin C.; McNamara, Bruce; Greenwood, Larry; Wittman, Richard; Soderquist, Charles; Woods, Vincent; VanDevender, Brent; Metz, Lori; Friese, Judah
2015-04-01
A novel reaction pathway for production of 240Am is reported. Models of reaction cross-sections in EMPIRE II suggest that deuteron-induced activation of a 240Pu target produces maximum yields of 240Am from 11.5 MeV incident deuterons. This activation had not been previously reported in the literature. A 240Pu target was activated under the modeled optimum conditions to produce 240Am. The modeled cross-section for the 240Pu(d, 2n)240Am reaction is on the order of 20-30 mbarn, but the experimentally estimated value is 5.6 ± 0.2 mbarn. We discuss reasons for the discrepancy as well as production of other Am isotopes that contaminate the final product.
Modeling and production of 240Am by deuteron-induced activation of a 240Pu target
Finn, Erin C.; McNamara, Bruce K.; Greenwood, Lawrence R.; Wittman, Richard S.; Soderquist, Chuck Z.; Woods, Vincent T.; VanDevender, Brent A.; Metz, Lori A.; Friese, Judah I.
2015-02-01
A novel reaction pathway for production of 240Am is reported. Models of reaction cross-sections in EMPIRE II suggests that deuteron-induced activation of a 240Pu target produces maximum yields of 240Am from 11.5 MeV incident deuterons. This activation had not been previously reported in the literature. A 240Pu target was activated under the modeled optimum conditions to produce 240Am. The modeled cross-section for the 240Pu(d, 2n)240Am reaction is on the order of 20-30 mbarn, but the experimentally estimated value is 5.3 ± 0.2 mbarn. We discuss reasons for the discrepancy as well as production of other Am isotopes that contaminate the final product.
Modeling spallation reactions in tungsten and uranium targets with the Geant4 toolkit
NASA Astrophysics Data System (ADS)
Malyshkin, Yury; Pshenichnov, Igor; Mishustin, Igor; Greiner, Walter
2012-02-01
We study primary and secondary reactions induced by 600 MeV proton beams in monolithic cylindrical targets made of natural tungsten and uranium by using Monte Carlo simulations with the Geant4 toolkit [1-3]. Bertini intranuclear cascade model, Binary cascade model and IntraNuclear Cascade Liège (INCL) with ABLA model [4] were used as calculational options to describe nuclear reactions. Fission cross sections, neutron multiplicity and mass distributions of fragments for 238U fission induced by 25.6 and 62.9 MeV protons are calculated and compared to recent experimental data [5]. Time distributions of neutron leakage from the targets and heat depositions are calculated. This project is supported by Siemens Corporate Technology.
Zhang, Li; Mager, Donald E
2015-10-01
Bortezomib is a reversible proteasome inhibitor with potent antineoplastic activity that exhibits dose- and time-dependent pharmacokinetics (PK). Proteasome-mediated bortezomib disposition is proposed as the primary source of its nonlinear and apparent nonstationary PK behavior. Single intravenous (IV) doses of bortezomib (0.25 and 1 mg/kg) were administrated to BALB/c mice, with blood and tissue samples obtained over 144 h, which were analyzed by LC/MS/MS. A physiologically based pharmacokinetic (PBPK) model incorporating tissue drug-target binding was developed to test the hypothesis of proteasome-mediated bortezomib disposition. The final model reasonably captured bortezomib plasma and tissue PK profiles, and parameters were estimated with good precision. The rank-order of model estimated tissue target density correlated well with experimentally measured proteasome concentrations reported in the literature, supporting the hypothesis that binding to proteasome influences bortezomib disposition. The PBPK model was further scaled-up to humans to assess the similarity of bortezomib disposition among species. Human plasma bortezomib PK profiles following multiple IV dosing (1.3 mg/m(2)) on days 1, 4, 8, and 11 were simulated by appropriately scaling estimated mouse parameters. Simulated and observed bortezomib concentrations after multiple dosing were in good agreement, suggesting target-mediated bortezomib disposition is likely for both mice and humans. Furthermore, the model predicts that renal impairment should exert minimal influence on bortezomib exposure in humans, confirming that bortezomib dose adjustment is not necessary for patients with renal impairment. PMID:26391023
De Velasco, Marco A.; Kura, Yurie; Yoshikawa, Kazuhiro; Nishio, Kazuto; Davies, Barry R.; Uemura, Hirotsugu
2016-01-01
The PI3K/AKT pathway is frequently altered in advanced human prostate cancer mainly through the loss of functional PTEN, and presents as potential target for personalized therapy. Our aim was to determine the therapeutic potential of the pan-AKT inhibitor, AZD5363, in PTEN-deficient prostate cancer. Here we used a genetically engineered mouse (GEM) model of PTEN-deficient prostate cancer to evaluate the in vivo pharmacodynamic and antitumor activity of AZD5363 in castration-naïve and castration-resistant prostate cancer. An additional GEM model, based on the concomitant inactivation of PTEN and Trp53 (P53), was established as an aggressive model of advanced prostate cancer and was used to further evaluate clinically relevant endpoints after treatment with AZD5363. In vivo pharmacodynamic studies demonstrated that AZD5363 effectively inhibited downstream targets of AKT. AZD5363 monotherapy significantly reduced growth of tumors in castration-naïve and castration-resistant models of PTEN-deficient prostate cancer. More importantly, AZD5363 significantly delayed tumor growth and improved overall survival and progression-free survival in PTEN/P53 double knockout mice. Our findings demonstrate that AZD5363 is effective against GEM models of PTEN-deficient prostate cancer and provide lines of evidence to support further investigation into the development of treatment strategies targeting AKT for the treatment of PTEN-deficient prostate cancer. PMID:26910118
NASA Astrophysics Data System (ADS)
Tate, Jennifer A.; Kett, Warren; NDong, Christian; Griswold, Karl E.; Hoopes, P. Jack
2013-02-01
Iron oxide nanoparticle (IONP) hyperthermia is a novel therapeutic strategy currently under consideration for the treatment of various cancer types. Systemic delivery of IONP followed by non-invasive activation via a local alternating magnetic field (AMF) results in site-specific energy deposition in the IONP-containing tumor. Targeting IONP to the tumor using an antibody or antibody fragment conjugated to the surface may enhance the intratumoral deposition of IONP and is currently being pursued by many nanoparticle researchers. This strategy, however, is subject to a variety of restrictions in the in vivo environment, where other aspects of IONP design will strongly influence the biodistribution. In these studies, various targeted IONP are compared to non-targeted controls. IONP were injected into BT-474 tumor-bearing NSG mice and tissues harvested 24hrs post-injection. Results indicate no significant difference between the various targeted IONP and the non-targeted controls, suggesting the IONP were prohibitively-sized to incur tumor penetration. Additional strategies are currently being pursued in conjuncture with targeted particles to increase the intratumoral deposition.
Serial diffusion MRI to monitor and model treatment response of the targeted nanotherapy CRLX101
Ng, Thomas S.C.; Wert, David; Sohi, Hargun; Procissi, Daniel; Colcher, David; Raubitschek, Andrew A.; Jacobs, Russell E.
2013-01-01
Purpose Targeted nanotherapies are being developed to improve tumor drug delivery and enhance therapeutic response. Techniques that can predict response will facilitate clinical translation and may help define optimal treatment strategies. We evaluated the efficacy of diffusion-weighted magnetic resonance imaging to monitor early response to CRLX101 nanotherapy (formerly IT-101), and explored its potential as a therapeutic response predictor using a mechanistic model of tumor cell-proliferation. Experimental Design Diffusion MRI was serially performed following CRLX101 administration in a mouse lymphoma model. Apparent diffusion coefficients (ADC) extracted from the data were used as treatment response biomarkers. Animals treated with irinotecan (CPT-11) and saline were imaged for comparison. ADC data were also input into a mathematical model of tumor growth. Histological analysis using cleaved-caspase 3, TUNEL, Ki-67 and H&E were conducted on tumor samples for correlation with imaging results. Results CRLX101 treated tumors at day 2, 4, 7 post-treatment exhibited changes in mean ADC=16 ± 9%, 24 ± 10% 49 ± 17% and size (TV)=−5 ± 3%, −30 ± 4% and −45 ± 13% respectively. Both parameters were statistically greater than controls (p(ADC) ≤ 0.02, and p(TV) ≤ 0.01 at day 4 and 7), and noticeably greater than CPT-11 treated tumors (ADC=5 ± 5%, 14 ± 7% and 18 ± 6%, TV=−15 ± 5%, −22 ± 13% and −26 ± 8%). Model-derived parameters for cell-proliferation obtained using ADC data distinguished CRLX101 treated tumors from controls (p = 0.02). Conclusions Temporal changes in ADC specified early CRLX101 treatment response and could be used to model image-derived cell-proliferation rates following treatment. Comparisons of targeted and non-targeted treatments highlight the utility of non-invasive imaging and modeling to evaluate, monitor and predict responses to targeted nanotherapeutics. PMID:23532891
Statistical modeling of targets and clutter in single-look non-polarimetric SAR imagery
Salazar, J.S.; Hush, D.R.; Koch, M.W.; Fogler, R.J.; Hostetler, L.D.
1998-08-01
This paper presents a Generalized Logistic (gLG) distribution as a unified model for Log-domain synthetic aperture Radar (SAR) data. This model stems from a special case of the G-distribution known as the G{sup 0}-distribution. The G-distribution arises from a multiplicative SAR model and has the classical K-distribution as another special case. The G{sup 0}-distribution, however, can model extremely heterogeneous clutter regions that the k-distribution cannot model. This flexibility is preserved in the unified gLG model, which is capable of modeling non-polarimetric SAR returns from clutter as well as man-made objects. Histograms of these two types of SAR returns have opposite skewness. The flexibility of the gLG model lies in its shape and shift parameters. The shape parameter describes the differing skewness between target and clutter data while the shift parameter compensates for movements in the mean as the shape parameter changes. A Maximum Likelihood (ML) estimate of the shape parameter gives an optimal measure of the skewness of the SAR data. This measure provides a basis for an optimal target detection algorithm.
Simulation of synthetic aperture imaging ladar (SAIL) for three-dimensional target model
NASA Astrophysics Data System (ADS)
Yi, Ning; Wu, Zhen-Sen
2010-11-01
In conventional imaging laser radar, the resolution of target is constrained by the diffraction-limited, which includes the beamwidth of the laser in the target plane and the telescope's aperture. Synthetic aperture imaging Ladar (SAIL) is an imaging technique which employs aperture synthesis with coherent laser radar, the resolution is determined by the total frequency spread of the source and is independent of range, so can achieve fine resolution in long range. Ray tracing is utilized here to obtain two-dimensional scattering properties from three-dimensional geometric model of actual target, and range-doppler algorithm is used for synthetic aperture process in laser image simulation. The results show that the SAIL can support better resolution.
Unsupervised Spatial Event Detection in Targeted Domains with Applications to Civil Unrest Modeling
Zhao, Liang; Chen, Feng; Dai, Jing; Hua, Ting; Lu, Chang-Tien; Ramakrishnan, Naren
2014-01-01
Twitter has become a popular data source as a surrogate for monitoring and detecting events. Targeted domains such as crime, election, and social unrest require the creation of algorithms capable of detecting events pertinent to these domains. Due to the unstructured language, short-length messages, dynamics, and heterogeneity typical of Twitter data streams, it is technically difficult and labor-intensive to develop and maintain supervised learning systems. We present a novel unsupervised approach for detecting spatial events in targeted domains and illustrate this approach using one specific domain, viz. civil unrest modeling. Given a targeted domain, we propose a dynamic query expansion algorithm to iteratively expand domain-related terms, and generate a tweet homogeneous graph. An anomaly identification method is utilized to detect spatial events over this graph by jointly maximizing local modularity and spatial scan statistics. Extensive experiments conducted in 10 Latin American countries demonstrate the effectiveness of the proposed approach. PMID:25350136
Positron backscattering from solid targets: Modeling of scattering processes via various approaches.
Kribaa, B; Rouabah, Z; Loirec, C Le; Champion, C; Bouarissa, N
2016-08-01
Monte Carlo simulation of 1-4keV positron backscattering from semi-infinite solid targets ranging from Be (z=4) to Au (z=79) with normal angle of incidence is here reported. In our study, the elastic and inelastic scattering cross sections are modeled by using various approaches based on either a classical or a quantum mechanical treatment. Calculations of positron backscattering coefficient are then reported for the solid targets of interest. The results obtained show a fairly good agreement with the data available in the literature. The dependence of the positron backscattering coefficient versus the atomic number of the solid target of interest has been investigated. In this respect, polynomial functions are proposed which does not require any recourse to Monte Carlo calculations. PMID:27200485
NASA Astrophysics Data System (ADS)
Yan, Jun; Yu, Kegen; Wu, Lenan
2014-12-01
To mitigate the non-line-of-sight (NLOS) effect, a three-step positioning approach is proposed in this article for target tracking. The possibility of each distance measurement under line-of-sight condition is first obtained by applying the truncated triangular probability-possibility transformation associated with fuzzy modeling. Based on the calculated possibilities, the measurements are utilized to obtain intermediate position estimates using the maximum likelihood estimation (MLE), according to identified measurement condition. These intermediate position estimates are then filtered using a linear Kalman filter (KF) to produce the final target position estimates. The target motion information and statistical characteristics of the MLE results are employed in updating the KF parameters. The KF position prediction is exploited for MLE parameter initialization and distance measurement selection. Simulation results demonstrate that the proposed approach outperforms the existing algorithms in the presence of unknown NLOS propagation conditions and achieves a performance close to that when propagation conditions are perfectly known.
NASA Astrophysics Data System (ADS)
Nachtmann, O.
2014-11-01
We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell-Yan process and soft photon production in hadron-hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell-Yan reaction. Also for Higgs-boson production in pp collisions via gluon-gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell-Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.
Nachtmann, O.
2014-11-15
We review ideas on the structure of the QCD vacuum which had served as motivation for the discussion of various non-standard QCD effects in high-energy reactions in articles from 1984 to 1995. These effects include, in particular, transverse-momentum and spin correlations in the Drell–Yan process and soft photon production in hadron–hadron collisions. We discuss the relation of the approach introduced in the above-mentioned articles to the approach, developed later, using transverse-momentum-dependent parton distributions (TDMs). The latter approach is a special case of our more general one which allows for parton entanglement in high-energy reactions. We discuss signatures of parton entanglement in the Drell–Yan reaction. Also for Higgs-boson production in pp collisions via gluon–gluon annihilation effects of entanglement of the two gluons are discussed and are found to be potentially important. These effects can be looked for in the current LHC experiments. In our opinion studying parton-entanglement effects in high-energy reactions is, on the one hand, very worthwhile by itself and, on the other hand, it allows to perform quantitative tests of standard factorisation assumptions. Clearly, the experimental observation of parton-entanglement effects in the Drell–Yan reaction and/or in Higgs-boson production would have a great impact on our understanding how QCD works in high-energy collisions.
Transverse target spin asymmetries in exclusive ρ0 muoproduction
NASA Astrophysics Data System (ADS)
Schmidt, Katharina; Nowak, Wolf-Dieter
2014-06-01
COMPASS has studied exclusive production of ρ0 mesons using a 160 GeV/c muon beam and a transversely polarised NH3 target. Five single-spin and three double-spin azimuthal aymmetries were measured in dependence on Q2, xBj, or pT2. Except the sin ϕS asymmetry, obtained to be - 0.019 ± 0.008(stat.) ± 0.003(syst.), all others were found to be consistent with zero within experimental uncertainties. Phenomenological GPD-based model calculations agree well with the data and interpret the result as evidence for the existence of chiral-odd, transverse generalised parton distributions.
Mimeault, Murielle; Batra, Surinder K.
2013-01-01
The in vivo zebrafish models have recently attracted great attention in molecular oncology to investigate multiple genetic alterations associated with the development of human cancers and validate novel anticancer drug targets. Particularly, the transparent zebrafish models can be used as a xenotransplantation system to rapidly assess the tumorigenicity and metastatic behavior of cancer stem and/or progenitor cells and their progenies. Moreover, the zebrafish models have emerged as powerful tools for an in vivo testing of novel anticancer agents and nanomaterials for counteracting tumor formation and metastases and improving the efficacy of current radiation and chemotherapeutic treatments against aggressive, metastatic and lethal cancers. PMID:22903142
Coon, Valerie; Laukert, Tamara; Pedone, Carolyn A; Laterra, John; Kim, K Jin; Fults, Daniel W
2010-09-01
The use of genetically engineered mice has provided insights into the molecular pathogenesis of the pediatric brain tumor medulloblastoma and revealed promising therapeutic targets. Ectopic expression of Sonic hedgehog (Shh) in cerebellar neural progenitor cells induces medulloblastomas in mice, and coexpression of hepatocyte growth factor (HGF) enhances Shh-induced tumor formation. To determine whether Shh + HGF-driven medulloblastomas were responsive to Shh signaling blockade and whether treatment response could be enhanced by combination therapy targeting both HGF and Shh signaling pathways, we carried out a survival study in mice. We induced medulloblastomas by retrovirus-mediated expression of Shh and HGF, after which we treated the mice systemically with (a) HGF-neutralizing monoclonal antibody L2G7, (b) Shh signaling inhibitor cyclopamine, (c) Shh-neutralizing monoclonal antibody 5E1, (d) L2G7 + cyclopamine, or (e) L2G7 + 5E1. We report that monotherapy targeting either HGF signaling or Shh signaling prolonged survival and that anti-HGF therapy had a more durable response than Shh-targeted therapy. The effect of L2G7 + 5E1 combination therapy on cumulative survival was equivalent to that of L2G7 monotherapy and that of L2G7 + cyclopamine therapy was worse. The principal mechanism by which Shh- and HGF-targeted therapies inhibited tumor growth was a potent apoptotic death response in tumor cells, supplemented by a weaker suppressive effect on proliferation. Our observation that combination therapy either failed to improve or even reduced survival in mice bearing Shh + HGF-induced medulloblastomas compared with monotherapy underscores the importance of preclinical testing of molecular-targeted therapies in animal models of tumors in which the targeted pathways are known to be active. PMID:20807782
Coon, Valerie; Laukert, Tamara; Pedone, Carolyn A.; Laterra, John; Kim, K. Jin; Fults, Daniel W.
2010-01-01
The use of genetically engineered mice has provided insights into the molecular pathogenesis of the pediatric brain tumor medulloblastoma and revealed promising therapeutic targets. Ectopic expression of Sonic Hedgehog (Shh) in cerebellar neural progenitor cells induces medulloblastomas in mice, and coexpression of hepatocyte growth factor (HGF) enhances Shh-induced tumor formation. To determine whether Shh+HGF–driven medulloblastomas were responsive to Shh signaling blockade and whether treatment response could be enhanced by combination therapy targeting both HGF and Shh signaling pathways, we carried out a survival study in mice. We induced medulloblastomas by retrovirus-mediated expression of Shh and HGF, after which we treated the mice systemically with (a) HGF-neutralizing monoclonal antibody L2G7, (b) Shh signaling inhibitor cyclopamine, (c) Shh-neutralizing monoclonal antibody 5E1, (d) L2G7+cyclopamine, or (e) L2G7+5E1. We report that monotherapy targeting either HGF signaling or Shh signaling prolonged survival and that anti-HGF therapy had a more durable response than Shh-targeted therapy. The effect of L2G7+5E1 combination therapy on cumulative survival was equivalent to that of L2G7 monotherapy and that of L2G7+cyclopamine therapy was worse. The principal mechanism by which Shh- and HGF-targeted therapies inhibited tumor growth was a potent apoptotic death response in tumor cells, supplemented by a weaker suppressive effect on proliferation. Our observation that combination therapy either failed to improve or even reduced survival in mice bearing Shh+HGF induced medulloblastomas compared with monotherapy underscores the importance of preclinical testing of molecular-targeted therapies in animal models of tumors in which the targeted pathways are known to be active. PMID:20807782
Modeling of Nike Experiments on Acceleration of Planar Targets Stabilized with a Short Spike
NASA Astrophysics Data System (ADS)
Metzler, N.; Velikovich, A. L.; Gardner, J. H.
2005-10-01
A short sub-ns laser pulse (spike) produces a decelerating shock wave and a rarefaction wave immediately behind it, shaping a density gradient in the target. The following main pulse ``rides'' this graded density profile. We have demonstrated how the deceleration of the ablation front following the shock wave suppresses laser imprint and delays perturbation growth in the target [1]. We report the results of 2D numerical modeling of experiments on Nike laser at NRL, with its recently developed short-pulse capability, for a low-energy spike which does not affect the target adiabat. We studied the effect of spike on laser imprint on smooth planar targets and on the growth of perturbations imposed as single-mode ripples on the irradiated surface of the targets. For all cases, delay of the onset and/or suppression of the rate of the mass perturbation growth due to the spike are robust and significant enough to be observable on Nike. [1] N. Metzler et al., Phys. Plasmas 6, 3283 (1999); 9, 5050 (2002); 10, 1897 (2003).
Design and modeling of spectral-thermal unmixing targets for airborne hyperspectral imagery
NASA Astrophysics Data System (ADS)
Clare, Phil
2006-05-01
Techniques to determine the proportions of constituent materials within a single pixel spectrum are well documented in the reflective (0.4-2.5μm) domain. The same capability is also desirable for the thermal (7-14μm) domain, but is complicated by the thermal contributions to the measured spectral radiance. Atmospheric compensation schemes for the thermal domain have been described along with methods for estimating the spectral emissivity from a spectral radiance measurement and hence the next stage to be tackled is the unmixing of thermal spectral signatures. In order to pursue this goal it is necessary to collect data of well-calibrated targets which will expose the limits of the available techniques and enable more robust methods to be designed. This paper describes the design of a set of ground targets for an airborne hyperspectral imager, which will test the effectiveness of available methods. The set of targets include panels to explore a number of difficult scenarios such as isothermal (different materials at identical temperature), isochromal (identical materials, but at differing temperatures), thermal adjacency and thermal point sources. Practical fabrication issues for heated targets and selection of appropriate materials are described. Mathematical modelling of the experiments has enabled prediction of at-sensor measured radiances which are used to assess the design parameters. Finally, a number of useful lessons learned during the fielding of these actual targets are presented to assist those planning future trials of thermal hyperspectral sensors.
Selection between Michaelis-Menten and target-mediated drug disposition pharmacokinetic models.
Yan, Xiaoyu; Mager, Donald E; Krzyzanski, Wojciech
2010-02-01
Target-mediated drug disposition (TMDD) models have been applied to describe the pharmacokinetics of drugs whose distribution and/or clearance are affected by its target due to high binding affinity and limited capacity. The Michaelis-Menten (M-M) model has also been frequently used to describe the pharmacokinetics of such drugs. The purpose of this study is to investigate conditions for equivalence between M-M and TMDD pharmacokinetic models and provide guidelines for selection between these two approaches. Theoretical derivations were used to determine conditions under which M-M and TMDD pharmacokinetic models are equivalent. Computer simulations and model fitting were conducted to demonstrate these conditions. Typical M-M and TMDD profiles were simulated based on literature data for an anti-CD4 monoclonal antibody (TRX1) and phenytoin administered intravenously. Both models were fitted to data and goodness of fit criteria were evaluated for model selection. A case study of recombinant human erythropoietin was conducted to qualify results. A rapid binding TMDD model is equivalent to the M-M model if total target density R ( tot ) is constant, and R ( tot ) K ( D ) /(K ( D ) + C) ( 2 ) < 1 where K ( D ) represents the dissociation constant and C is the free drug concentration. Under these conditions, M-M parameters are defined as: V ( max ) = k ( int ) R ( tot ) V ( c ) and K ( m ) = K ( D ) where k ( int ) represents an internalization rate constant, and V ( c ) is the volume of the central compartment. R ( tot ) is constant if and only if k ( int ) = k ( deg,) where k ( deg ) is a degradation rate constant. If the TMDD model predictions are not sensitive to k ( int ) or k ( deg ) parameters, the condition of R ( tot ) K ( D ) /(K ( D ) + C) ( 2 ) < 1 alone can preserve the equivalence between rapid binding TMDD and M-M models. The model selection process for drugs that exhibit TMDD should involve a full mechanistic model as well as reduced models. The best model
Collaborative effects-based planning using adversary models and target set optimization
NASA Astrophysics Data System (ADS)
Pioch, Nicholas J.; Daniels, Troy; Pielech, Bradford
2004-08-01
The Strategy Development Tool (SDT), sponsored by AFRL-IFS, supports effects-based planning at multiple levels of war through three core capabilities: plan authoring, center of gravity (COG) modeling and analysis, and target system analysis. This paper describes recent extensions to all three of these capabilities. The extended plan authoring subsystem supports collaborative planning in which a user delegates elaboration of objectives to other registered users. A suite of collaboration tools allows planners to assign planning tasks, submit plan fragments, and review submitted plans, while a collaboration server transparently handles message routing and persistence. The COG modeling subsystem now includes an enhanced adversary modeling tool that provides a lightweight ontology for building temporal causal models relating enemy goals, beliefs, actions, and resources across multiple types of COGs. Users may overlay friendly interventions, analyze their impact on enemy COGs, and automatically incorporate the causal chains stemming from the best interventions into the current plan. Finally, the target system analysis subsystem has been extended with option generation tools that use network-based optimization algorithms to select candidate target set options to achieve specified effects.
Laser induced plasma on copper target, a non-equilibrium model
Oumeziane, Amina Ait Liani, Bachir; Parisse, Jean-Denis
2014-02-15
The aim of this work is to present a comprehensive numerical model for the UV laser ablation of metal targets, it focuses mainly on the prediction of laser induced plasma thresholds, the effect of the laser-plasma interaction, and the importance of the electronic non-equilibrium in the laser induced plume and its expansion in the background gas. This paper describes a set of numerical models for laser-matter interaction between 193-248 and 355 nm lasers and a copper target. Along with the thermal effects inside the material resulting from the irradiation of the latter with the pulsed laser, the laser-evaporated matter interaction and the plasma formation are thoroughly modelled. In the laser induced plume, the electronic nonequilibrium and the laser beam absorption have been investigated. Our calculations of the plasmas ignition thresholds on copper targets have been validated and compared to experimental as well as theoretical results. Comparison with experiment data indicates that our results are in good agreement with those reported in the literature. Furthermore, the inclusion of electronic non-equilibrium in our work indicated that this important process must be included in models of laser ablation and plasma plume formation.
[Passive ranging of infrared target using oxygen A-band and Elsasser model].
Li, Jin-Hua; Wang, Zhao-Ba; Wang Zhi
2014-09-01
Passive ranging method of short range and single band was developed based on target radiation and attenuation characteristic of oxygen spectrum absorption. The relation between transmittance of oxygen A band and range of measured target was analyzed. Radiation strength distribution of measured target can be obtained according to the distribution law of absorption coefficient with environmental parameters. Passive ranging mathematical model of short ranges was established using Elsasser model with Lorentz line shape based on the computational methods of band average transmittance and high-temperature gas radiation narrowband model. The range of measured object was obtained using transmittance fitting with test data calculation and theoretical model. Besides, ranging precision was corrected considering the influence of oxygen absorption with enviromental parameter. The ranging experiment platform was established. The source was a 10 watt black body, and a grating spectrometer with 17 cm(-1) resolution was used. In order to improve the light receiving efficiency, light input was collected with 23 mm calibre telescope. The test data was processed for different range in 200 m. The results show that the transmittance accuracy was better than 2.18% in short range compared to the test data with predicted value in the same conditions. PMID:25532368
Electromagnetic modeling of FOPEN targets and clutter in a lossy half-space
NASA Astrophysics Data System (ADS)
Sullivan, Anders J.
2001-08-01
There has been considerable interest in evaluating the use of a low frequency, ultra-wideband (UWB) imaging radar to detect tactical vehicles concealed by foliage. This interest stems from the fact that while high-frequency imagery has shown near-literal imaging capability for targets positioned in open areas, it cannot penetrate tree canopy effectively. However, at low frequencies, the tree canopy is effectively transparent. We examine the issues related to foliage penetrating (FOPEN) radar by first considering VHF scattering from a T-72 tank over soil using a method of moments (MoM) analysis. The MoM analysis considers arbitrary dielectric and perfectly conducting targets in a layered medium, with the lossy, dispersive layers representing the typical layered character of many soils. The solution obtained via the MoM is based on a full-wave formulation of Maxwell's equations. For the clutter, we model both tree trunks as well as a full tree model (trunk and branch structure). The tree trunk is modeled as a dielectric body of revolution (BoR), again using a MoM half-space analysis, while the 'tree' is modeled as an arbitrary dielectric target.
Targeted Proteomics-Driven Computational Modeling of Macrophage S1P Chemosensing.
Manes, Nathan P; Angermann, Bastian R; Koppenol-Raab, Marijke; An, Eunkyung; Sjoelund, Virginie H; Sun, Jing; Ishii, Masaru; Germain, Ronald N; Meier-Schellersheim, Martin; Nita-Lazar, Aleksandra
2015-10-01
Osteoclasts are monocyte-derived multinuclear cells that directly attach to and resorb bone. Sphingosine-1-phosphate (S1P)(1) regulates bone resorption by functioning as both a chemoattractant and chemorepellent of osteoclast precursors through two G-protein coupled receptors that antagonize each other in an S1P-concentration-dependent manner. To quantitatively explore the behavior of this chemosensing pathway, we applied targeted proteomics, transcriptomics, and rule-based pathway modeling using the Simmune toolset. RAW264.7 cells (a mouse monocyte/macrophage cell line) were used as model osteoclast precursors, RNA-seq was used to identify expressed target proteins, and selected reaction monitoring (SRM) mass spectrometry using internal peptide standards was used to perform absolute abundance measurements of pathway proteins. The resulting transcript and protein abundance values were strongly correlated. Measured protein abundance values, used as simulation input parameters, led to in silico pathway behavior matching in vitro measurements. Moreover, once model parameters were established, even simulated responses toward stimuli that were not used for parameterization were consistent with experimental findings. These findings demonstrate the feasibility and value of combining targeted mass spectrometry with pathway modeling for advancing biological insight. PMID:26199343
An information theoretic model of target discrimination using hyperspectral and multisensor data
NASA Astrophysics Data System (ADS)
Wadströmer, Niclas; Renhorn, Ingmar
2008-04-01
We address the problem of target discrimination using hyperspektral and multisensor data. The problem is of significance to detection and classification of low signature targets such as landmines. The problem will be described with stochastic models and by using information theoretic concepts we will derive limits to system performance in terms of probability of false alarm and probablility of detection. The stochastic model is suitable to evaluate and optimize sensor parameters and sensor configurations. We will for example investigate how much information different combinations of spectral and spatial data will give. With the stochastic model sensors with different types of characteristics can be compared and the contribution of the different sensors and configurations can be evaluated. Besides the optimization of different sensor configurations with respect to specific applications, the stochastic model will be used to evaluate different anomaly detectors. The strength of our approach is shown by examples from an analysis of measurements on a natural scene with various objects using an electro-optical hyperspectral sensor and several other sensors. We expect that our approach will give significant indications on how to choose and configure sensors for efficient and reliable target discrimination.
Syme, A M; McQuarrie, S A; Middleton, J W; Fallone, B G
2003-05-21
A simple model has been developed to investigate the dosimetry of micrometastases in the peritoneal cavity during intraperitoneal targeted liposomal radioimmunotherapy. The model is applied to free-floating tumours with radii between 0.005 cm and 0.1 cm. Tumour dose is assumed to come from two sources: free liposomes in solution in the peritoneal cavity and liposomes bound to the surface of the micrometastases. It is assumed that liposomes do not penetrate beyond the surface of the tumours and that the total amount of surface antigen does not change over the course of treatment. Integrated tumour doses are expressed as a function of biological parameters that describe the rates at which liposomes bind to and unbind from the tumour surface, the rate at which liposomes escape from the peritoneal cavity and the tumour surface antigen density. Integrated doses are translated into time-dependent tumour control probabilities (TCPs). The results of the work are illustrated in the context of a therapy in which liposomes labelled with Re-188 are targeted at ovarian cancer cells that express the surface antigen CA-125. The time required to produce a TCP of 95% is used to investigate the importance of the various parameters. The relative contributions of surface-bound radioactivity and unbound radioactivity are used to assess the conditions required for a targeted approach to provide an improvement over a non-targeted approach during intraperitoneal radiation therapy. Using Re-188 as the radionuclide, the model suggests that, for microscopic tumours, the relative importance of the surface-bound radioactivity increases with tumour size. This is evidenced by the requirement for larger antigen densities on smaller tumours to affect an improvement in the time required to produce a TCP of 95%. This is because for the smallest tumours considered, the unbound radioactivity is often capable of exerting a tumouricidal effect before the targeting agent has time to accumulate
Army Research Laboratory ultrawide-band testbed radar and comparisons of target data with models
NASA Astrophysics Data System (ADS)
Happ, Lynn; Ressler, Marc A.; Sturgess, Keith; Bennett, Matthew; Carin, Lawrence; Vitebskiey, S.
1995-06-01
Over the years, many different sensor types have been evaluated in an attempt to satisfy the need to detect and discriminate tactical and strategic targets concealed in foliage or underground. In large measure these early efforts were disappointing because of the lack of appropriate technologies. Today, by taking advantage of commercial off-the-shelf processors, an advanced analog-to-digital (A/D) converter, and lessons learned, a highly capable impulse radar has been designed and assembled to investigate an ultra-wideband (UWB) radar approach for ground penetration (GPEN) radar studies. The testbed consists of several major subsystems that are modular to allow for the evaluation of alternate approaches. The testbed radar subsystem consist of the antenna, the transmitter, the A/D converter, the processor/data storage system, the timing and control assembly, the positioning subsystem, and the operator interface computer. Many of the subassemblies exist as standard 19 inch rackmount units or as VME-compatible printed circuit assemblies. Much of the system operation is controlled by software, allowing easy modifications or other future upgrades. Data collected with this upgraded system will be used for measuring and analyzing the basic phenomenology of radar propagation through the ground and the response of targets, clutter, and targets embedded in clutter. One important aspect of basic phenomenology studies is validation of models with data. Range profiles of synthetic aperature radar (SAR) processed data from the Army Research Laboratory UWB radar is compared to 3D method of moments models for similar targets. In this paper, a mix of canonical and mine-like targets are examined and compared. Comparison between data and models shows some correlation, thus validating the need for further investigation.
A target detection model predicting field observer performance in maritime scenes
NASA Astrophysics Data System (ADS)
Culpepper, Joanne B.; Wheaton, Vivienne C.
2014-10-01
The U.S. Army's target acquisition models, the ACQUIRE and Target Task Performance (TTP) models, have been employed for many years to assess the performance of thermal infrared sensors. In recent years, ACQUIRE and the TTP models have been adapted to assess the performance of visible sensors. These adaptations have been primarily focused on the performance of an observer viewing a display device. This paper describes an implementation of the TTP model to predict field observer performance in maritime scenes. Predictions of the TTP model implementation were compared to observations of a small watercraft taken in a field trial. In this field trial 11 Australian Navy observers viewed a small watercraft in an open ocean scene. Comparisons of the observed probability of detection to predictions of the TTP model implementation showed the normalised RSS metric overestimated the probability of detection. The normalised Pixel Contrast using a literature value for V50 yielded a correlation of 0.58 between the predicted and observed probability of detection. With a measured value of N50 or V50 for the small watercraft used in this investigation, this implementation of the TTP model may yield stronger correlation with observed probability of detection.
Study of a dense, coronal thick target source with the microwave data and 3D modeling
NASA Astrophysics Data System (ADS)
Fleishman, Gregory; Xu, Yan
2015-04-01
We present a detailed 3D modeling of a dense, coronal thick target X-ray flare using the GX Simulator tool, photospheric magnetic measurements, and microwave data. The developed model offers a remarkable agreement between the synthesized and observed spectra and images in both X-ray and microwave domains, which validates the entire model. The flaring loop parameters validated via the modeling are fully consistent with those derived from the X-ray spectral fit, but do not easily agree with those derived from the fit of the X-ray image sizes computed at various energies. Specifically, the plasma density obtained in the modeling is noticeably smaller than that derived from the size fit. The performed modeling suggests that the accelerated electrons are trapped at the coronal part of the flaring loop by a turbulence, while proves that the data are clearly inconsistent with the electron magnetic trapping in the weak diffusion regime mediated by the Coulomb collisions. Thus, the modeling confirms the interpretation of the coronal thick-target sources as the sites of electron acceleration in flares.This work was supported in part by NSF grants AGS-1250374, AGS-1262772, AGS-1153424, AGS-1348513, and AGS-1408703 and NASA grants NNX14AC87G and NNX-13AG13G to New Jersey Institute of Technology.
Implications of different stopping power models on target heating simulations using HYDRA
NASA Astrophysics Data System (ADS)
Veitzer, Seth; Stoltz, Peter; Barnard, John; Henestroza, Enrique; Kerbel, Gary; Marinak, Marty
2007-11-01
Accurate numerical simulations of ion driven Warm Dense Matter experiments requires accurate models of stopping powers for targets with temperatures up to a few eV. For finite temperature targets, energy loss of beam ions is comprised of contributions from nuclear stopping, bound electron stopping, and free electron stopping. We compare two different stopping power algorithms and the implications on target heating for two different beams corresponding to the current Neutralized Drift Compression Experiment (NDCX) and proposed NDCX II experiments. The NDCX I beam has a beam energy much lower than the Bragg peak while the NDCX II beam is designed to enter the target just above the Bragg peak, and exit just below. The first stopping power algorithm is based on the classical Bethe-Bloch formulation as is currently implemented in the HYDRA simulation code. The second algorithm is based on rescaling of experimental protonic stopping powers as developed by Brandt and Kitagawa for nuclear and bound electronic stopping, and free electron stopping following the model developed by Peter and Meyer-ter-Vehn.
Molecular Inversion Probes for targeted resequencing in non-model organisms
Niedzicka, M.; Fijarczyk, A.; Dudek, K.; Stuglik, M.; Babik, W.
2016-01-01
Applications that require resequencing of hundreds or thousands of predefined genomic regions in numerous samples are common in studies of non-model organisms. However few approaches at the scale intermediate between multiplex PCR and sequence capture methods are available. Here we explored the utility of Molecular Inversion Probes (MIPs) for the medium-scale targeted resequencing in a non-model system. Markers targeting 112 bp of exonic sequence were designed from transcriptome of Lissotriton newts. We assessed performance of 248 MIP markers in a sample of 85 individuals. Among the 234 (94.4%) successfully amplified markers 80% had median coverage within one order of magnitude, indicating relatively uniform performance; coverage uniformity across individuals was also high. In the analysis of polymorphism and segregation within family, 77% of 248 tested MIPs were confirmed as single copy Mendelian markers. Genotyping concordance assessed using replicate samples exceeded 99%. MIP markers for targeted resequencing have a number of advantages: high specificity, high multiplexing level, low sample requirement, straightforward laboratory protocol, no need for preparation of genomic libraries and no ascertainment bias. We conclude that MIP markers provide an effective solution for resequencing targets of tens or hundreds of kb in any organism and in a large number of samples. PMID:27046329
Molecular Inversion Probes for targeted resequencing in non-model organisms.
Niedzicka, M; Fijarczyk, A; Dudek, K; Stuglik, M; Babik, W
2016-01-01
Applications that require resequencing of hundreds or thousands of predefined genomic regions in numerous samples are common in studies of non-model organisms. However few approaches at the scale intermediate between multiplex PCR and sequence capture methods are available. Here we explored the utility of Molecular Inversion Probes (MIPs) for the medium-scale targeted resequencing in a non-model system. Markers targeting 112 bp of exonic sequence were designed from transcriptome of Lissotriton newts. We assessed performance of 248 MIP markers in a sample of 85 individuals. Among the 234 (94.4%) successfully amplified markers 80% had median coverage within one order of magnitude, indicating relatively uniform performance; coverage uniformity across individuals was also high. In the analysis of polymorphism and segregation within family, 77% of 248 tested MIPs were confirmed as single copy Mendelian markers. Genotyping concordance assessed using replicate samples exceeded 99%. MIP markers for targeted resequencing have a number of advantages: high specificity, high multiplexing level, low sample requirement, straightforward laboratory protocol, no need for preparation of genomic libraries and no ascertainment bias. We conclude that MIP markers provide an effective solution for resequencing targets of tens or hundreds of kb in any organism and in a large number of samples. PMID:27046329
Shamay, Yosi; Golan, Moran; Tyomkin, Dalia; David, Ayelet
2016-05-10
Polymer-drug conjugates that can actively target the tumor vasculature have emerged as an attractive technology for improving the therapeutic efficacy of cytotoxic drugs. We have recently provided, for the first time, in vivo evidence showing the significant advantage of the E-selectin-targeted N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-doxorubicin conjugate, P-(Esbp)-DOX, in inhibiting primary tumor growth and preventing the formation and development of cancer metastases. Here, we describe the design of a vascular endothelial growth factor receptor (VEGFR)-1-targeted HPMA copolymer-DOX conjugate (P-(F56)-DOX) that can actively and simultaneously target different cell types in the tumor microenvironment, such as endothelial cells (ECs), bone marrow-derived cells and many human cancer cells of diverse tumor origin. The VEGFR-1-targeted copolymer was tested for its binding, internalization and in vitro cytotoxicity in ECs (bEnd.3 and cEND cells) and cancer cells (B16-F10, 3LL and HT29). The in vivo anti-cancer activity of P-(F56)-DOX was then tested in two tumor-bearing mice (TBM) models (i.e., primary Lewis lung carcinoma (3LL) tumors and B16-F10 melanoma pulmonary metastases), relative to that of the E-selectin-targeted system (P-(Esbp)-DOX) that solely targets ECs. Our results indicate that the binding and internalization profiles of the VEGFR-1-targeted copolymer were superior towards ECs as compared to cancer cells and correlated well to the level of VEGFR-1 expression in cells. Accordingly, the VEGFR-1-targeted copolymer (P-(F56)-DOX) was more toxic towards bEnd.3 cells than to cancer cells, and exhibited significantly higher cytotoxicity than did the non-targeted control copolymer. P-(F56)-DOX inhibited 3LL tumor growth and significantly prolonged the survival of mice with B16-F10 pulmonary metastases. When compared to a system that actively targets only tumor vascular ECs, P-(F56)-DOX and P-(Esbp)-DOX exhibited comparable efficacy in slowing the
Folate Receptor-Targeted Multimodality Imaging of Ovarian Cancer in a Novel Syngeneic Mouse Model
2015-01-01
A new transplantable ovarian tumor model is presented using a novel folate receptor (FR) positive, murine ovarian cancer cell line that emulates the human disease and induces widespread intraperitoneal (i.p.) tumors in immunocompetent mice within 4–8 weeks of implantation. Tumor development was monitored using a new positron emission tomography (PET) FR-targeting reporter with PET/computerized tomography (PET/CT) and fluorescence molecular tomography (FMT) using a commercial FR-targeting reporter. Conventional structural magnetic resonance imaging (MRI) was also performed. Adult female C57BL/6 mice were injected i.p. with 6 × 106 MKP-L FR+ cells. Imaging was performed weekly beginning 2 weeks after tumor induction. The albumin-binding, FR-targeting ligand cm09 was radiolabeled with the positron emitter 68Ga and used to image the tumors with a small animal PET/CT. The FR-reporter FolateRSense 680 (PerkinElmer) was used for FMT and flow cytometry. Preclinical MRI (7 T) without FR-targeting was compared with the PET and FMT molecular imaging. Tumors were visible by all three imaging modalities. PET/CT had the highest imaging sensitivity at 3–3.5 h postadministration (mean %IA/g mean > 6) and visualized tumors earlier than the other two modalities with lower kidney uptake (mean %IA/g mean < 17) than previously reported FR-targeting agents in late stage disease. FMT showed relatively low FR-targeted agent in the bladder and kidneys, but yielded the lowest anatomical image resolution. MRI produced the highest resolution images, but it was difficult to distinguish tumors from abdominal organs during early progression since a FR-targeting MRI reporter was not used. Nevertheless, there was good correlation of imaging biomarkers between the three modalities. Tumors in the mouse ovarian cancer model could be detected using FR-targeted imaging as early as 2 weeks post i.p. injection of tumor cells. An imaging protocol should combine one or more of the modalities, e
Optimization of vascular-targeting drugs in a computational model of tumor growth
NASA Astrophysics Data System (ADS)
Gevertz, Jana
2012-04-01
A biophysical tool is introduced that seeks to provide a theoretical basis for helping drug design teams assess the most promising drug targets and design optimal treatment strategies. The tool is grounded in a previously validated computational model of the feedback that occurs between a growing tumor and the evolving vasculature. In this paper, the model is particularly used to explore the therapeutic effectiveness of two drugs that target the tumor vasculature: angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs). Using sensitivity analyses, the impact of VDA dosing parameters is explored, as is the effects of administering a VDA with an AI. Further, a stochastic optimization scheme is utilized to identify an optimal dosing schedule for treatment with an AI and a chemotherapeutic. The treatment regimen identified can successfully halt simulated tumor growth, even after the cessation of therapy.
Hoshida, Yujin; Fuchs, Bryan C.; Tanabe, Kenneth K.
2013-01-01
Chronic fibrotic liver diseases such as viral hepatitis eventually develop liver cirrhosis, which causes occurrence of hepatocellular carcinoma (HCC). Given the limited therapeutic efficacy in advanced HCC, prevention of HCC development could be an effective strategy for improving patient prognosis. However, there is still no established therapy to meet the goal. Studies have elucidated a wide variety of molecular mechanisms and signaling pathways involved in HCC development. Genetically-engineered or chemically-treated experimental models of cirrhosis and HCC have been developed and shown their potential value in investigating molecular therapeutic targets and diagnostic biomarkers for HCC prevention. In this review, we overview potential targets of prevention and currently available experimental models, and discuss strategies to translate the findings into clinical practice. PMID:22873223
A mathematical model for a distributed attack on targeted resources in a computer network
NASA Astrophysics Data System (ADS)
Haldar, Kaushik; Mishra, Bimal Kumar
2014-09-01
A mathematical model has been developed to analyze the spread of a distributed attack on critical targeted resources in a network. The model provides an epidemic framework with two sub-frameworks to consider the difference between the overall behavior of the attacking hosts and the targeted resources. The analysis focuses on obtaining threshold conditions that determine the success or failure of such attacks. Considering the criticality of the systems involved and the strength of the defence mechanism involved, a measure has been suggested that highlights the level of success that has been achieved by the attacker. To understand the overall dynamics of the system in the long run, its equilibrium points have been obtained and their stability has been analyzed, and conditions for their stability have been outlined.
General or idiosyncratic item effects: What is the good target for models?
Courrieu, Pierre; Rey, Arnaud
2015-09-01
Recently, Adelman, Marquis, Sabatos-DeVito, and Estes (2013) formulated severe criticisms about approaches based on averaging item response times (RTs) over participants and associated methods for estimating the amount of item variance that models should try to account for. Their main argument was that item effects include stable idiosyncratic effects. In this comment, we provide supplementary empirical evidence that this assertion is indeed valid. However, the actual implications of this result are not those defended in Adelman et al. (2013), where there seems to be confusion about the precision of measures and the nature of target effects. Indeed, basic statistical considerations show that any arbitrary data precision level can be achieved in all cases using an appropriate number of observations per item, whereas general and idiosyncratic item effects are both targets of interest for modeling but in different objectives. (PsycINFO Database Record PMID:26348202
QCD-aware partonic jet clustering for truth-jet flavour labelling
NASA Astrophysics Data System (ADS)
Buckley, Andy; Pollard, Chris
2016-02-01
We present an algorithm for deriving partonic flavour labels to be applied to truth particle jets in Monte Carlo event simulations. The inputs to this approach are final pre-hadronisation partons, to remove dependence on unphysical details such as the order of matrix element calculation and shower generator frame recoil treatment. These are clustered using standard jet algorithms, modified to restrict the allowed pseudojet combinations to those in which tracked flavour labels are consistent with QCD and QED Feynman rules. The resulting algorithm is shown to be portable between the major families of shower generators, and largely insensitive to many possible systematic variations: it hence offers significant advantages over existing ad hoc labelling schemes. However, it is shown that contamination from multi-parton scattering simulations can disrupt the labelling results. Suggestions are made for further extension to incorporate more detailed QCD splitting function kinematics, robustness improvements, and potential uses for truth-level physics object definitions and tagging.
Electroweakino pair production at the LHC: NLO SUSY-QCD corrections and parton-shower effects
NASA Astrophysics Data System (ADS)
Baglio, Julien; Jäger, Barbara; Kesenheimer, Matthias
2016-07-01
We present a set of NLO SUSY-QCD calculations for the pair production of neutralinos and charginos at the LHC, and their matching to parton-shower programs in the framework of the POWHEG-BOX program package. The code we have developed provides a SUSY Les Houches Accord interface for setting supersymmetric input parameters. Decays of the neutralinos and charginos and parton-shower effects can be simulated with PYTHIA. To illustrate the capabilities of our program, we present phenomenological results for a representative SUSY parameter point. We find that NLO-QCD corrections increase the production rates for neutralinos and charginos significantly. The impact of parton-shower effects on distributions of the weakinos is small, but non-negligible for jet distributions.
Reinforcement Learning of Targeted Movement in a Spiking Neuronal Model of Motor Cortex
Chadderdon, George L.; Neymotin, Samuel A.; Kerr, Cliff C.; Lytton, William W.
2012-01-01
Sensorimotor control has traditionally been considered from a control theory perspective, without relation to neurobiology. In contrast, here we utilized a spiking-neuron model of motor cortex and trained it to perform a simple movement task, which consisted of rotating a single-joint “forearm” to a target. Learning was based on a reinforcement mechanism analogous to that of the dopamine system. This provided a global reward or punishment signal in response to decreasing or increasing distance from hand to target, respectively. Output was partially driven by Poisson motor babbling, creating stochastic movements that could then be shaped by learning. The virtual forearm consisted of a single segment rotated around an elbow joint, controlled by flexor and extensor muscles. The model consisted of 144 excitatory and 64 inhibitory event-based neurons, each with AMPA, NMDA, and GABA synapses. Proprioceptive cell input to this model encoded the 2 muscle lengths. Plasticity was only enabled in feedforward connections between input and output excitatory units, using spike-timing-dependent eligibility traces for synaptic credit or blame assignment. Learning resulted from a global 3-valued signal: reward (+1), no learning (0), or punishment (−1), corresponding to phasic increases, lack of change, or phasic decreases of dopaminergic cell firing, respectively. Successful learning only occurred when both reward and punishment were enabled. In this case, 5 target angles were learned successfully within 180 s of simulation time, with a median error of 8 degrees. Motor babbling allowed exploratory learning, but decreased the stability of the learned behavior, since the hand continued moving after reaching the target. Our model demonstrated that a global reinforcement signal, coupled with eligibility traces for synaptic plasticity, can train a spiking sensorimotor network to perform goal-directed motor behavior. PMID:23094042
Lescarbeau, Rebecca S; Lei, Liang; Bakken, Katrina K; Sims, Peter A; Sarkaria, Jann N; Canoll, Peter; White, Forest M
2016-06-01
Glioblastoma (GBM) is the most common malignant primary brain cancer. With a median survival of about a year, new approaches to treating this disease are necessary. To identify signaling molecules regulating GBM progression in a genetically engineered murine model of proneural GBM, we quantified phosphotyrosine-mediated signaling using mass spectrometry. Oncogenic signals, including phosphorylated ERK MAPK, PI3K, and PDGFR, were found to be increased in the murine tumors relative to brain. Phosphorylation of CDK1 pY15, associated with the G2 arrest checkpoint, was identified as the most differentially phosphorylated site, with a 14-fold increase in phosphorylation in the tumors. To assess the role of this checkpoint as a potential therapeutic target, syngeneic primary cell lines derived from these tumors were treated with MK-1775, an inhibitor of Wee1, the kinase responsible for CDK1 Y15 phosphorylation. MK-1775 treatment led to mitotic catastrophe, as defined by increased DNA damage and cell death by apoptosis. To assess the extensibility of targeting Wee1/CDK1 in GBM, patient-derived xenograft (PDX) cell lines were also treated with MK-1775. Although the response was more heterogeneous, on-target Wee1 inhibition led to decreased CDK1 Y15 phosphorylation and increased DNA damage and apoptosis in each line. These results were also validated in vivo, where single-agent MK-1775 demonstrated an antitumor effect on a flank PDX tumor model, increasing mouse survival by 1.74-fold. This study highlights the ability of unbiased quantitative phosphoproteomics to reveal therapeutic targets in tumor models, and the potential for Wee1 inhibition as a treatment approach in preclinical models of GBM. Mol Cancer Ther; 15(6); 1332-43. ©2016 AACR. PMID:27196784
Optical model analyses of galactic cosmic ray fragmentation in hydrogen targets
NASA Technical Reports Server (NTRS)
Townsend, Lawrence W.
1993-01-01
Quantum-mechanical optical model methods for calculating cross sections for the fragmentation of galactic cosmic ray nuclei by hydrogen targets are presented. The fragmentation cross sections are calculated with an abrasion-ablation collision formalism. Elemental and isotopic cross sections are estimated and compared with measured values for neon, sulfur, and calcium ions at incident energies between 400A MeV and 910A MeV. Good agreement between theory and experiment is obtained.
A State Space Model for Spatial Updating of Remembered Visual Targets during Eye Movements.
Mohsenzadeh, Yalda; Dash, Suryadeep; Crawford, J Douglas
2016-01-01
In the oculomotor system, spatial updating is the ability to aim a saccade toward a remembered visual target position despite intervening eye movements. Although this has been the subject of extensive experimental investigation, there is still no unifying theoretical framework to explain the neural mechanism for this phenomenon, and how it influences visual signals in the brain. Here, we propose a unified state-space model (SSM) to account for the dynamics of spatial updating during two types of eye movement; saccades and smooth pursuit. Our proposed model is a non-linear SSM and implemented through a recurrent radial-basis-function neural network in a dual Extended Kalman filter (EKF) structure. The model parameters and internal states (remembered target position) are estimated sequentially using the EKF method. The proposed model replicates two fundamental experimental observations: continuous gaze-centered updating of visual memory-related activity during smooth pursuit, and predictive remapping of visual memory activity before and during saccades. Moreover, our model makes the new prediction that, when uncertainty of input signals is incorporated in the model, neural population activity and receptive fields expand just before and during saccades. These results suggest that visual remapping and motor updating are part of a common visuomotor mechanism, and that subjective perceptual constancy arises in part from training the visual system on motor tasks. PMID:27242452
Sequential targeting of CFTR by BAC vectors generates a novel pig model of cystic fibrosis.
Klymiuk, N; Mundhenk, L; Kraehe, K; Wuensch, A; Plog, S; Emrich, D; Langenmayer, M C; Stehr, M; Holzinger, A; Kröner, C; Richter, A; Kessler, B; Kurome, M; Eddicks, M; Nagashima, H; Heinritzi, K; Gruber, A D; Wolf, E
2012-05-01
Cystic fibrosis (CF) is the most common lethal inherited disease in Caucasians and is caused by mutations in the CFTR gene. The disease is incurable and medical treatment is limited to the amelioration of symptoms or secondary complications. A comprehensive understanding of the disease mechanisms and the development of novel treatment options require appropriate animal models. Existing CF mouse models fail to reflect important aspects of human CF. We thus generated a CF pig model by inactivating the CFTR gene in primary porcine cells by sequential targeting using modified bacterial artificial chromosome vectors. These cells were then used to generate homozygous CFTR mutant piglets by somatic cell nuclear transfer. The homozygous CFTR mutants lack CFTR protein expression and display severe malformations in the intestine, respiratory tract, pancreas, liver, gallbladder, and male reproductive tract. These phenotypic abnormalities closely resemble both the human CF pathology as well as alterations observed in a recently published CF pig model which was generated by a different gene targeting strategy. Our new CF pig model underlines the value of the CFTR-deficient pig for gaining new insight into the disease mechanisms of CF and for the development and evaluation of new therapeutic strategies. This model will furthermore increase the availability of CF pigs to the scientific community. PMID:22170306
A State Space Model for Spatial Updating of Remembered Visual Targets during Eye Movements
Mohsenzadeh, Yalda; Dash, Suryadeep; Crawford, J. Douglas
2016-01-01
In the oculomotor system, spatial updating is the ability to aim a saccade toward a remembered visual target position despite intervening eye movements. Although this has been the subject of extensive experimental investigation, there is still no unifying theoretical framework to explain the neural mechanism for this phenomenon, and how it influences visual signals in the brain. Here, we propose a unified state-space model (SSM) to account for the dynamics of spatial updating during two types of eye movement; saccades and smooth pursuit. Our proposed model is a non-linear SSM and implemented through a recurrent radial-basis-function neural network in a dual Extended Kalman filter (EKF) structure. The model parameters and internal states (remembered target position) are estimated sequentially using the EKF method. The proposed model replicates two fundamental experimental observations: continuous gaze-centered updating of visual memory-related activity during smooth pursuit, and predictive remapping of visual memory activity before and during saccades. Moreover, our model makes the new prediction that, when uncertainty of input signals is incorporated in the model, neural population activity and receptive fields expand just before and during saccades. These results suggest that visual remapping and motor updating are part of a common visuomotor mechanism, and that subjective perceptual constancy arises in part from training the visual system on motor tasks. PMID:27242452
Partons and Jets in a Strongly-Coupled Plasma from AdS/CFT
NASA Astrophysics Data System (ADS)
Iancu, E.
2008-12-01
We give a pedagogical review of recent progress towards understanding the response of a strongly coupled plasma at finite temperature to a hard probe. The plasma is that of the N=4 supersymmetric Yang-Mills theory and the hard probe is a virtual photon, or, more precisely, an R-current. Via the gauge/gravity duality, the problem of the current interacting with the plasma is mapped onto the gravitational interaction between a Maxwell field and a black hole embedded in the AdS5×S5 geometry. The physical interpretation of the AdS/CFT results can be then reconstructed with the help of the ultraviolet/infrared correspondence. We thus deduce that, for sufficiently high energy, the photon (or any other hard probe: a quark, a gluon, or a meson) disappears into the plasma via a universal mechanism, which is medium-induced quasi-democratic parton branching: the current develops a parton cascade such that, at any step in the branching process, the energy is almost equally divided among the daughter partons. The branching rate is controlled by the plasma which acts on the coloured partons with a constant force sim T2. When reinterpreted in the plasma infinite momentum frame, the same AdS/CFT results suggest a parton picture for the plasma structure functions, in which all the partons have fallen at very small values of Bjorken's x. For a time-like current in the vacuum, quasi-democratic branching implies that there should be no jets in electron-positron annihilation at strong coupling, but only a spatially isotropic distribution of hadronic matter.
Xing, Rui; Chen, Xue-Dong; Zhou, Yan-Feng; Zhang, Jue; Su, Yuan-Yuan; Qiu, Jian-Feng; Sima, Yang-Hu; Zhang, Ke-Qin; He, Yao; Xu, Shi-Qing
2016-01-01
The use of quantum dots (QDs) in biological imaging applications and targeted drug delivery is expected to increase. However, the efficiency of QDs in drug targeting needs to be improved. Here, we show that amino acids linked to CdTe QDs significantly increased the targeted transfer efficiency and biological safety in the invertebrate model Bombyx mori. Compared with bare QDs530, the transfer efficiency of Ala- and Gly-conjugated QDs (QDs530-Ala and QDs530-Gly) in circulatory system increased by 2.6 ± 0.3 and 1.5 ± 0.3 times, and increased by 7.8 ± 0.9 and 2.9 ± 0.2 times in target tissue silk glands, respectively, after 24 h of QDs exposure. Meanwhile, the amount of conjugated QDs decreased by (68.4 ± 4.4)% and (46.7 ± 9.1)% in the non-target tissue fat body, and the speed at which they entered non-target circulating blood cells significantly decreased. The resultant QDs530-Ala revealed a better structural integrity in tissues and a longer retention time in hemolymph than that of QDs530 after exposure via the dorsal vessel. On the other hand, QDs530-Ala significantly reduced the toxicity to hemocytes, silk gland, and fat body, and reduced the amount of reactive oxygen species (ROS) in tissues. PMID:26806642
Xing, Rui; Chen, Xue-Dong; Zhou, Yan-Feng; Zhang, Jue; Su, Yuan-Yuan; Qiu, Jian-Feng; Sima, Yang-Hu; Zhang, Ke-Qin; He, Yao; Xu, Shi-Qing
2016-01-01
The use of quantum dots (QDs) in biological imaging applications and targeted drug delivery is expected to increase. However, the efficiency of QDs in drug targeting needs to be improved. Here, we show that amino acids linked to CdTe QDs significantly increased the targeted transfer efficiency and biological safety in the invertebrate model Bombyx mori. Compared with bare QDs530, the transfer efficiency of Ala- and Gly-conjugated QDs (QDs530-Ala and QDs530-Gly) in circulatory system increased by 2.6 ± 0.3 and 1.5 ± 0.3 times, and increased by 7.8 ± 0.9 and 2.9 ± 0.2 times in target tissue silk glands, respectively, after 24 h of QDs exposure. Meanwhile, the amount of conjugated QDs decreased by (68.4 ± 4.4)% and (46.7 ± 9.1)% in the non-target tissue fat body, and the speed at which they entered non-target circulating blood cells significantly decreased. The resultant QDs530-Ala revealed a better structural integrity in tissues and a longer retention time in hemolymph than that of QDs530 after exposure via the dorsal vessel. On the other hand, QDs530-Ala significantly reduced the toxicity to hemocytes, silk gland, and fat body, and reduced the amount of reactive oxygen species (ROS) in tissues. PMID:26806642
A linear-encoding model explains the variability of the target morphology in regeneration
Lobo, Daniel; Solano, Mauricio; Bubenik, George A.; Levin, Michael
2014-01-01
A fundamental assumption of today's molecular genetics paradigm is that complex morphology emerges from the combined activity of low-level processes involving proteins and nucleic acids. An inherent characteristic of such nonlinear encodings is the difficulty of creating the genetic and epigenetic information that will produce a given self-assembling complex morphology. This ‘inverse problem’ is vital not only for understanding the evolution, development and regeneration of bodyplans, but also for synthetic biology efforts that seek to engineer biological shapes. Importantly, the regenerative mechanisms in deer antlers, planarian worms and fiddler crabs can solve an inverse problem: their target morphology can be altered specifically and stably by injuries in particular locations. Here, we discuss the class of models that use pre-specified morphological goal states and propose the existence of a linear encoding of the target morphology, making the inverse problem easy for these organisms to solve. Indeed, many model organisms such as Drosophila, hydra and Xenopus also develop according to nonlinear encodings producing linear encodings of their final morphologies. We propose the development of testable models of regeneration regulation that combine emergence with a top-down specification of shape by linear encodings of target morphology, driving transformative applications in biomedicine and synthetic bioengineering. PMID:24402915
NASA Astrophysics Data System (ADS)
Azimov, D.; Bishop, R.
2012-09-01
A complete analytical integration of the kinematic and dynamic equations of motion and applications of their integrals to targeting and guidance schemes for various dynamical models of various flight vehicles are presented. The general integral of these equations consists of six independent first integrals of motion and describes a class of non-steady flight trajectories in a maneuver plane. These first integrals represent explicit relationships for time, components of position and velocity vectors, and propulsive and aerodynamic accelerations. This explicitness with respect to the problem parameters can make these relationships useful in the design of airspace trajectories, and targeting and guidance schemes. It is also shown that the equations represent a 3rd-order vector differential equation used to develop the nonlinear maneuver model of a flight vehicle, and the state estimation and prediction schemes. Similarity in the dynamical models makes the first integrals valid for re-entry vehicles and missiles. An illustrative example has shown that the general integral provides a complete set of analytical solutions for nonlinear tracking, targeting, guidance and control problems with a wide range of terminal conditions, accelerations due to propulsive thrust and aerodynamic forces.
A linear-encoding model explains the variability of the target morphology in regeneration.
Lobo, Daniel; Solano, Mauricio; Bubenik, George A; Levin, Michael
2014-03-01
A fundamental assumption of today's molecular genetics paradigm is that complex morphology emerges from the combined activity of low-level processes involving proteins and nucleic acids. An inherent characteristic of such nonlinear encodings is the difficulty of creating the genetic and epigenetic information that will produce a given self-assembling complex morphology. This 'inverse problem' is vital not only for understanding the evolution, development and regeneration of bodyplans, but also for synthetic biology efforts that seek to engineer biological shapes. Importantly, the regenerative mechanisms in deer antlers, planarian worms and fiddler crabs can solve an inverse problem: their target morphology can be altered specifically and stably by injuries in particular locations. Here, we discuss the class of models that use pre-specified morphological goal states and propose the existence of a linear encoding of the target morphology, making the inverse problem easy for these organisms to solve. Indeed, many model organisms such as Drosophila, hydra and Xenopus also develop according to nonlinear encodings producing linear encodings of their final morphologies. We propose the development of testable models of regeneration regulation that combine emergence with a top-down specification of shape by linear encodings of target morphology, driving transformative applications in biomedicine and synthetic bioengineering. PMID:24402915
Spectral Target Detection using Physics-Based Modeling and a Manifold Learning Technique
NASA Astrophysics Data System (ADS)
Albano, James A.
Identification of materials from calibrated radiance data collected by an airborne imaging spectrometer depends strongly on the atmospheric and illumination conditions at the time of collection. This thesis demonstrates a methodology for identifying material spectra using the assumption that each unique material class forms a lower-dimensional manifold (surface) in the higher-dimensional spectral radiance space and that all image spectra reside on, or near, these theoretic manifolds. Using a physical model, a manifold characteristic of the target material exposed to varying illumination and atmospheric conditions is formed. A graph-based model is then applied to the radiance data to capture the intricate structure of each material manifold, followed by the application of the commute time distance (CTD) transformation to separate the target manifold from the background. Detection algorithms are then applied in the CTD subspace. This nonlinear transformation is based on a random walk on a graph and is derived from an eigendecomposition of the pseudoinverse of the graph Laplacian matrix. This work provides a geometric interpretation of the CTD transformation, its algebraic properties, the atmospheric and illumination parameters varied in the physics-based model, and the influence the target manifold samples have on the orientation of the coordinate axes in the transformed space. This thesis concludes by demonstrating improved detection results in the CTD subspace as compared to detection in the original spectral radiance space.
Dynamic Data Driven Applications Systems (DDDAS) modeling for automatic target recognition
NASA Astrophysics Data System (ADS)
Blasch, Erik; Seetharaman, Guna; Darema, Frederica
2013-05-01
The Dynamic Data Driven Applications System (DDDAS) concept uses applications modeling, mathematical algorithms, and measurement systems to work with dynamic systems. A dynamic systems such as Automatic Target Recognition (ATR) is subject to sensor, target, and the environment variations over space and time. We use the DDDAS concept to develop an ATR methodology for multiscale-multimodal analysis that seeks to integrated sensing, processing, and exploitation. In the analysis, we use computer vision techniques to explore the capabilities and analogies that DDDAS has with information fusion. The key attribute of coordination is the use of sensor management as a data driven techniques to improve performance. In addition, DDDAS supports the need for modeling from which uncertainty and variations are used within the dynamic models for advanced performance. As an example, we use a Wide-Area Motion Imagery (WAMI) application to draw parallels and contrasts between ATR and DDDAS systems that warrants an integrated perspective. This elementary work is aimed at triggering a sequence of deeper insightful research towards exploiting sparsely sampled piecewise dense WAMI measurements - an application where the challenges of big-data with regards to mathematical fusion relationships and high-performance computations remain significant and will persist. Dynamic data-driven adaptive computations are required to effectively handle the challenges with exponentially increasing data volume for advanced information fusion systems solutions such as simultaneous target tracking and ATR.
Construction of a mouse model of factor VIII deficiency by gene targeting
Bi, L.; Lawler, A.; Gearhart, J.
1994-09-01
To develop a small animal model of hemophilia A for gene therapy experiments, we set out to construct a mouse model for factor VIII deficiency by gene targeting. First, we screened a mouse liver cDNA library using a human FVIII cDNA probe. We cloned a 2.6 Kb partial mouse factor VIII cDNA which extends from 800 base pairs of the 3{prime} end of exon 14 to the 5{prime} end of exon 26. A mouse genomic library made from strain 129 was then screened to obtain genomic fragments covering the exons desired for homologous recombination. Two genomic clones were obtained, and one covering exon 15 through 22 was used for gene targeting. To make gene targeting constructs, a 5.8 Kb genomic DNA fragment covering exons 15 to 19 of the mouse FVIII gene was subcloned, and the neo expression cassette was inserted into exons 16 and 17 separately by different strategies. These two constructs were named MFVIIIC-16 and MFVIIIC-17. The constructs were linearized and transfected into strain 129 mouse ES cells by electroporation. Factor VIII gene-knockout ES cell lines were selected by G-418 and screened by genomic Southern blots. Eight exon 16 targeted cell lines and five exon 17 targeted cell lines were obtained. Three cell lines from each construct were injected into blastocysts and surgically transferred into foster mothers. Multiple chimeric mice with 70-90% hair color derived from the ES-cell genotype were seen with both constructs. Germ line transmission of the ES-cell genotype has been obtained for the MFVIIIC-16 construct, and multiple hemophilia A carrier females have been identified. Factor VIII-deficient males will be conceived soon.
Constraints on spin-dependent parton distributions at large x from global QCD analysis
NASA Astrophysics Data System (ADS)
Jimenez-Delgado, P.; Avakian, H.; Melnitchouk, W.
2014-11-01
We investigate the behavior of spin-dependent parton distribution functions (PDFs) at large parton momentum fractions x in the context of global QCD analysis. We explore the constraints from existing deep-inelastic scattering data, and from theoretical expectations for the leading x → 1 behavior based on hard gluon exchange in perturbative QCD. Systematic uncertainties from the dependence of the PDFs on the choice of parametrization are studied by considering functional forms motivated by orbital angular momentum arguments. Finally, we quantify the reduction in the PDF uncertainties that may be expected from future high-x data from Jefferson Lab at 12 GeV.
Studies of Parton Propagation and Hadron Formation in the Space-Time Domain
Brooks, Will; Hakobyan, Hayk
2008-10-13
Over the past decade, new data from HERMES, Jefferson Lab, Fermilab, and RHIC that connect to parton propagation and hadron formation have become available. Semi-inclusive DIS on nuclei, the Drell-Yan reaction, and heavy-ion collisions all bring different kinds of information on parton propagation within a medium, while the most direct information on hadron formation comes from the DIS data. Over the next decade one can hope to begin to understand these data within a unified picture. We briefly survey the most relevant data and the common elements of the physics picture, then highlight the new Jefferson Lab data, and close with a prospective for the future.
The Drell-Yan process as a testing ground for parton distributions up to LHC
NASA Astrophysics Data System (ADS)
Basso, Eduardo; Bourrely, Claude; Pasechnik, Roman; Soffer, Jacques
2016-04-01
The Drell-Yan massive dilepton production in hadron-hadron collisions provides a unique tool, complementary to Deep Inelastic Scattering, for improving our understanding of hadronic substructure and in particular for testing parton distributions. We will consider measurements of the differential and double-differential Drell-Yan cross sections from FNAL Tevatron up to CERN LHC energies and they will be compared to the predictions of perturbative QCD calculations using most recent sets (CT14 and MMHT14) of parton distribution functions, as well as those provided by the statistical approach.
An O([alpha][sub s]) Monte Carlo for W production with parton showering
Baer, H.A.
1991-01-01
We construct an event generator for p[bar p][yields]W[sup +]X[yields]e[sup +][nu]X including complete O([alpha][sub s]) corrections, and interface with initial and final state parton showers. Problems with negative weights and with double counting higher order parton radiation are averted. We present results for W+n-jet production, and compare with results from complete tree-level calculations, and shower calculations off of the lowest order 2[yields]2 sub-process. We also compute the [sub qT](W) distribution, and compare with data.
An O({alpha}{sub s}) Monte Carlo for W production with parton showering
Baer, H.A.
1991-12-31
We construct an event generator for p{bar p}{yields}W{sup +}X{yields}e{sup +}{nu}X including complete O({alpha}{sub s}) corrections, and interface with initial and final state parton showers. Problems with negative weights and with double counting higher order parton radiation are averted. We present results for W+n-jet production, and compare with results from complete tree-level calculations, and shower calculations off of the lowest order 2{yields}2 sub-process. We also compute the {sub qT}(W) distribution, and compare with data.
nCTEQ15 - Global analysis of nuclear parton distributions with uncertainties
Kusina, A.; Jezo, T.; Clark, D. B.; Keppel, Cynthia; Lyonnet, F.; Morfin, Jorge; Olness, F. I.; Owens, Jeff; Schienbein, I.
2015-09-01
We present the first official release of the nCTEQ nuclear parton distribution functions with errors. The main addition to the previous nCTEQ PDFs is the introduction of PDF uncertainties based on the Hessian method. Another important addition is the inclusion of pion production data from RHIC that give us a handle on constraining the gluon PDF. This contribution summarizes our results from arXiv:1509.00792 and concentrates on the comparison with other groups providing nuclear parton distributions.
[Relevance of animal models in the development of compounds targeting multidrug resistant cancer].
Füredi, András; Tóth, Szilárd; Hámori, Lilla; Nagy, Veronika; Tóvári, József; Szakács, Gergely
2015-12-01
Anticancer compounds are typically identified in in vitro screens. Unfortunately, the in vitro drug sensitivity of cell lines does not reflect treatment efficiency in animal models, and neither show acceptable correlation to clinical results. While cell lines and laboratory animals can be readily "cured", the treatment of malignancies remains hampered by the multidrug resistance (MDR) of tumors. Genetically engineered mouse models (GEMMs) giving rise to spontaneous tumors offer a new possibility to characterize the evolution of drug resistance mechanisms and to target multidrug resistant cancer. PMID:26665195
Brochado, Ana Rita; Patil, Kiran Raosaheb
2014-01-01
Identification of metabolic engineering strategies for rerouting intracellular fluxes towards a desired product is often a challenging task owing to the topological and regulatory complexity of metabolic networks. Genome-scale metabolic models help tackling this complexity through systematic consideration of mass balance and reaction directionality constraints over the entire network. Here, we describe how genome-scale metabolic models can be used for identifying gene deletion targets leading to increased production of the desired product. Vanillin production in Saccharomyces cerevisiae is used as a case study throughout this chapter. PMID:24744040
NASA Astrophysics Data System (ADS)
Liu, Qing; Zhan, Yong-hong; Yang, Di; Zeng, Chang-e.
2014-11-01
In this paper, we try to find a model that can apply to predict the polarization characteristics of the targets on the ground correctly. In the first place, we give an introduction to several kinds of existing models which are divided into three categories: Empirical models are precise but occupy too much source of computer; Physical-based models can predict the phenomenon of reflection exactly but hardly get the final results; Semi-empirical models have both advantages mentioned above and avoid their disadvantages effectively. Then we make an analysis of the Priest-Germer (PG) pBRDF model, one of semi-empirical models, which is suitable for our study. The methods of parameters inversing and testing are proposed based on this model and the test system from which we can get enough data to verify the accuracy of the model is designed independently. At last, we make a simulation of the whole process of the parameters inversing based on PG pBRDF model. From the analysis of the simulation curves, we briefly know the direction we go in the following work to make an amendment.
Electroproduction in the Target Fragmentation Region
NASA Astrophysics Data System (ADS)
Avagyan, Harut
2014-09-01
The Semi-Inclusive DIS process in the Target Fragmentation Region (TFR), when the hadron is produced in the fragmentation process of the target remnants, can be described through the so-called Fracture Functions (FFs). They represent the joint probability of producing the final hadron from the target remnants, when a parton of the target nucleon is struck by the virtual photon in a hard scattering process. Like the ordinary parton distribution functions, the FFs are universal objects, thus they can be measured in one experiment at a given hard scale and then used to make predictions for other experiments, at another hard scale. Measurements of the Lambda multiplicities and polarization asymmetries in TFR, in particular, will provide information on corresponding Fracture Functions. The study of its Q2 dependence at JLab and EIC also will test the perturbative framework implied by Fracture Functions, simultaneously encoding the information on the interacting parton and on the fragmentation of the spectator system. We will present ongoing studies of electroproduction in TFR at Jefferson Lab, and proposed future measurement at upgraded JLab and Electron Ion Collider.
The last glacial termination: targets for climate modelling and proxy-based reconstructions
NASA Astrophysics Data System (ADS)
Renssen, Hans; Blockley, Simon P.; Rasmussen, Sune O.; Roche, Didier M.; Valdes, Paul J.; Nisancioglu, Kerim M.; Working Group 3 Members Of Intimate
2013-04-01
During the last glacial termination, the climate system experienced a major reorganisation, making this time interval a crucial period for our understanding of climate change. Despite a basic understanding of these changes and a reasonable level of agreement between data and model simulations, a deeper understanding of the last glacial termination remains a long standing goal: we are still faced with the dual challenge of reconstructing the climate history from incomplete and uncertain proxy data, and accurately simulating the climate history with physics-based climate models. There are, however, significant advantages in attempting to reliably integrate palaeoclimate data with model simulations, not least because it is necessary to examine the limitations of both current models and palaeoclimate records before testing possible forcing mechanisms. For the model studies, palaeodata play a crucial role, both as a source of (1) climate forcings for the modelling experiments and (2) palaeoclimate information that is required for model evaluation. Therefore, interaction between the modelling and data communities is essential. For this purpose, and with the last termination as a target, a working group has been set up within the INTIMATE (INTegration of Ice core, MArine and TErrestrial records of the last termination) COST Action (http://cost-es0907.geoenvi.org). We report on the outcome of a workshop of this working group, discussing the state of knowledge of the forcings and various aspects of climate variability during the last termination. We focus in particular on the main uncertainties in the climate signals and the forcings. We discuss the major problems that must be solved to make further progress in our understanding. This requires a joint effort of paleodata, chronology, and climate modelling communities. A number of specific targets for these communities are identified.
A Model for NAD(P)H:Quinoneoxidoreductase 1 (NQO1) Targeted Individualized Cancer Chemotherapy
Begleiter, Asher; El-Gabalawy, Nadia; Lange, Laurie; Leith, Marsha K.; Guziec, Lynn J.; Guziec, Frank S.
2009-01-01
NQO1 (NAD(P)H:quinoneoxidoreductase 1) is a reductive enzyme that is an important activator of bioreductive antitumor agents. NQO1 activity varies in individual tumors but is generally higher in tumor cells than in normal cells. NQO1 has been used as a target for tumor specific drug development. We investigated a series of bioreductive benzoquinone mustard analogs as a model for NQO1 targeted individualized cancer chemotherapy. We compared the tumor cell growth inhibitory activity of benzoquinone mustard analogs with sterically bulky groups of different size and placed at different positions on the benzoquinone ring, using tumor cell lines with different levels of NQO1. We demonstrated that functional groups of different steric size could be used to produce a series of bioreductive antitumor agents that were activated by different levels of NQO1 in tumor cells. This series of drugs could then be used to target cells with specific levels of NQO1 for growth inhibition and to avoid damage to normal cells, like bone marrow cells, that have low levels of NQO1. This approach could be used to develop new bioreductive antitumor agents for NQO1 targeted individualized cancer chemotherapy. PMID:21904446
Improvement of Hand Movement on Visual Target Tracking by Assistant Force of Model-Based Compensator
NASA Astrophysics Data System (ADS)
Ide, Junko; Sugi, Takenao; Nakamura, Masatoshi; Shibasaki, Hiroshi
Human motor control is achieved by the appropriate motor commands generating from the central nerve system. A test of visual target tracking is one of the effective methods for analyzing the human motor functions. We have previously examined a possibility for improving the hand movement on visual target tracking by additional assistant force through a simulation study. In this study, a method for compensating the human hand movement on visual target tracking by adding an assistant force was proposed. Effectiveness of the compensation method was investigated through the experiment for four healthy adults. The proposed compensator precisely improved the reaction time, the position error and the variability of the velocity of the human hand. The model-based compensator proposed in this study is constructed by using the measurement data on visual target tracking for each subject. The properties of the hand movement for different subjects can be reflected in the structure of the compensator. Therefore, the proposed method has possibility to adjust the individual properties of patients with various movement disorders caused from brain dysfunctions.
Yilmaz, L. Safak; Loy, Alexander; Wright, Erik S.; Wagner, Michael; Noguera, Daniel R.
2012-01-01
Application of high-density microarrays to the diagnostic analysis of microbial communities is challenged by the optimization of oligonucleotide probe sensitivity and specificity, as it is generally unfeasible to experimentally test thousands of probes. This study investigated the adjustment of hybridization stringency using formamide with the idea that sensitivity and specificity can be optimized during probe design if the hybridization efficiency of oligonucleotides with target and non-target molecules can be predicted as a function of formamide concentration. Sigmoidal denaturation profiles were obtained using fluorescently labeled and fragmented 16S rRNA gene amplicon of Escherichia coli as the target with increasing concentrations of formamide in the hybridization buffer. A linear free energy model (LFEM) was developed and microarray-specific nearest neighbor rules were derived. The model simulated formamide melting with a denaturant m-value that increased hybridization free energy (ΔG°) by 0.173 kcal/mol per percent of formamide added (v/v). Using the LFEM and specific probe sets, free energy rules were systematically established to predict the stability of single and double mismatches, including bulged and tandem mismatches. The absolute error in predicting the position of experimental denaturation profiles was less than 5% formamide for more than 90 percent of probes, enabling a practical level of accuracy in probe design. The potential of the modeling approach for probe design and optimization is demonstrated using a dataset including the 16S rRNA gene of Rhodobacter sphaeroides as an additional target molecule. The LFEM and thermodynamic databases were incorporated into a computational tool (ProbeMelt) that is freely available at http://DECIPHER.cee.wisc.edu. PMID:22952791
Geiger, K.; Longacre, R.; Srivastava, D.K.
1999-02-01
VNI is a general-purpose Monte-Carlo event-generator, which includes the simulation of lepton-lepton, lepton-hadron, lepton-nucleus, hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions. It uses the real-time evolution of parton cascades in conjunction with a self-consistent hadronization scheme, as well as the development of hadron cascades after hadronization. The causal evolution from a specific initial state (determined by the colliding beam particles) is followed by the time-development of the phase-space densities of partons, pre-hadronic parton clusters, and final-state hadrons, in position-space, momentum-space and color-space. The parton-evolution is described in terms of a space-time generalization of the familiar momentum-space description of multiple (semi)hard interactions in QCD, involving 2 {r_arrow} 2 parton collisions, 2 {r_arrow} 1 parton fusion processes, and 1 {r_arrow} 2 radiation processes. The formation of color-singlet pre-hadronic clusters and their decays into hadrons, on the other hand, is treated by using a spatial criterion motivated by confinement and a non-perturbative model for hadronization. Finally, the cascading of produced prehadronic clusters and of hadrons includes a multitude of 2 {r_arrow} n processes, and is modeled in parallel to the parton cascade description. This paper gives a brief review of the physics underlying VNI, as well as a detailed description of the program itself. The latter program description emphasizes easy-to-use pragmatism and explains how to use the program (including simple examples), annotates input and control parameters, and discusses output data provided by it.
NASA Astrophysics Data System (ADS)
ZEUS Collaboration; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Brock, I.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Crittenden, J.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hebbel, K.; Hillert, S.; Koch, W.; Kötz, U.; Kowalski, H.; Labes, H.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Wolf, G.; Wollmer, U.; Whitmore, J. J.; Wichmann, R.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Parenti, A.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Bodmann, B.; Gendner, N.; Holm, U.; Salehi, H.; Wick, K.; Yildirim, A.; Ziegler, A.; Carli, T.; Garfagnini, A.; Gialas, I.; Lohrmann, E.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Corriveau, F.; Padhi, S.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Y. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Große-Knetter, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Limentani, S.; Longhin, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Iannotti, L.; Oh, B. Y.; Saull, P. R. B.; Toothacker, W. S.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Plucinski, P.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, J.; Zakrzewski, J. A.; Z˙arnecki, A. F.; Adamus, M.; Deppe, O.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kçira, D.; Lammers, S.; Reeder, D. D.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.
2001-06-01
The photoproduction of prompt photons, together with an accompanying jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. A study of the effective transverse momentum,
NASA Astrophysics Data System (ADS)
Caldwell, Robert R.; Doran, Michael
2004-05-01
We perform a detailed comparison of the Wilkinson Microwave Anisotropy Probe measurements of the cosmic microwave background (CMB) temperature and polarization anisotropy with the predictions of quintessence cosmological models of dark energy. We consider a wide range of quintessence models, including a constant equation of state, a simply parametrized, time-evolving equation of state, a class of models of early quintessence, and scalar fields with an inverse-power law potential. We also provide a joint fit to the Cosmic Background Imager (CBI) and Arcminute Cosmology Bolometer Array Receiver (ACBAR) CMB data, and the type 1a supernovae. Using these select constraints we identify viable, target models which should prove useful for numerical studies of large scale structure formation, and to rapidly estimate the impact to the concordance region when new or improved observations become available.
An EMG-level muscle model for a fast arm movement to target.
Kilmer, W; Kroll, W; Congdon, V
1982-01-01
A model of human muscle action is presented for a maximally fast, large-amplitude forearm movement to target. The inputs to the model are approximately the biceps and triceps EMG envelopes over a single movement. The model's output gives the corresponding displacement angle of the forearm about a fixed elbow position as a function of time. The idea of the model is to conceive of both EMG input drives as successions of millisecond input pulses, with each pulse resulting in a muscle tension twitch. Every twitch is amplitude-scaled, parametrically-shaped, and duration-limited as a function of the muscle's contractile history thus far in the movement. The muscle tension at any time t is the sum of the residual tension levels of all twitches begun before t. The model was developed and tested with special reference to two subjects: one, according to the model dynamics, was a comparatively slow-twitch type and the other modelled as a fast-twitch type. Good agreement was found between model output and subject response data whenever the subject's EMG's were "synchronous". The model can be used to characterize each subject's responses by a suite of twitch characteristics. This will enable us to check the accepted but now suspect correlation between muscle biopsy- and performance-determined muscle twitch type. PMID:7093365
Navarro, Xavier
2016-02-01
Peripheral nerve injuries usually lead to severe loss of motor, sensory and autonomic functions in the patients. Due to the complex requirements for adequate axonal regeneration, functional recovery is often poorly achieved. Experimental models are useful to investigate the mechanisms related to axonal regeneration and tissue reinnervation, and to test new therapeutic strategies to improve functional recovery. Therefore, objective and reliable evaluation methods should be applied for the assessment of regeneration and function restitution after nerve injury in animal models. This review gives an overview of the most useful methods to assess nerve regeneration, target reinnervation and recovery of complex sensory and motor functions, their values and limitations. The selection of methods has to be adequate to the main objective of the research study, either enhancement of axonal regeneration, improving regeneration and reinnervation of target organs by different types of nerve fibres, or increasing recovery of complex sensory and motor functions. It is generally recommended to use more than one functional method for each purpose, and also to perform morphological studies of the injured nerve and the reinnervated targets. PMID:26228942
Identification of Treatment Targets in a Genetic Mouse Model of Voluntary Methamphetamine Drinking.
Phillips, T J; Mootz, J R K; Reed, C
2016-01-01
Methamphetamine has powerful stimulant and euphoric effects that are experienced as rewarding and encourage use. Methamphetamine addiction is associated with debilitating illnesses, destroyed relationships, child neglect, violence, and crime; but after many years of research, broadly effective medications have not been identified. Individual differences that may impact not only risk for developing a methamphetamine use disorder but also affect treatment response have not been fully considered. Human studies have identified candidate genes that may be relevant, but lack of control over drug history, the common use or coabuse of multiple addictive drugs, and restrictions on the types of data that can be collected in humans are barriers to progress. To overcome some of these issues, a genetic animal model comprised of lines of mice selectively bred for high and low voluntary methamphetamine intake was developed to identify risk and protective alleles for methamphetamine consumption, and identify therapeutic targets. The mu opioid receptor gene was supported as a target for genes within a top-ranked transcription factor network associated with level of methamphetamine intake. In addition, mice that consume high levels of methamphetamine were found to possess a nonfunctional form of the trace amine-associated receptor 1 (TAAR1). The Taar1 gene is within a mouse chromosome 10 quantitative trait locus for methamphetamine consumption, and TAAR1 function determines sensitivity to aversive effects of methamphetamine that may curb intake. The genes, gene interaction partners, and protein products identified in this genetic mouse model represent treatment target candidates for methamphetamine addiction. PMID:27055611
NASA Astrophysics Data System (ADS)
Namazu, Michiko; Fujimori, Shinichiro; Matsuoka, Yuzuru
In this study, a recursive dynamic Computable General Equilibrium (CGE) model which can deal with Greenhouse Gas (GHG) constraint is applied to Japan. Based on several references, Japan's emissions reduction targets are determined as 25% reduction from 1990 level by 2020 and 80% reduction from 2005 level by 2050 in this study. Several cases with different scenarios for nuclear power plant, international emissions trading, and CO2 Capture and Strage (CCS) technology are simulated using the CGE model. By comparison among the results of each case, the effects, especially economic effects are evaluated and analyzed quantitatively. The results show that the most important counter measure to achieve GHG emissions reduction targets in Japan is whether Japan joins international emissions trading or not. In a no-trading case, in which GHG emissions constraints are imposed and Japan does not participate to the trading, GHG reduction costs reach 2,560 USD/tCO2-eq,yr (2005 price) in 2050. In addition, Gross Domestic Product (GDP) decreases 3.8% compared with a counter measure case in which GHG constraints are imposed but the emissions trading is allowed. The results also show that in case Japan targets no nuclear power plants in 2050, CCS technology and emissions trading are able to make up for the gap resulted from the nuclear power decrease. About the speed of CCS technology introduction, the share of power plants with CCS technology is changed depended on the speed; however, GDP and GHG reduction costs do not affected so much.
Tuberculosis control in China: use of modelling to develop targets and policies
Wang, Lixia; Zhang, Hui; Ruan, Yunzhou; Chin, Daniel P; Dye, Christopher
2015-01-01
Abstract It is unclear if current programmes in China can achieve the post-2015 global targets for tuberculosis – 50% reduction in incidence and a 75% reduction in mortality by 2025. Chinese policy-makers need to maintain the recent decline in the prevalence of tuberculosis, while revising control policies to cope with an epidemic of drug-resistant tuberculosis and the effects of ongoing health reform. Health reforms are expected to shift patients from tuberculosis dispensaries to designated hospitals. We developed a mathematical model of tuberculosis control in China to help set appropriate targets and prioritize interventions that might be implemented in the next 10 years. This model indicates that, even under the most optimistic scenario – improved treatment in tuberculosis dispensaries, introduction of a new effective regimen for the treatment of drug-susceptible tuberculosis and optimal care of cases of multidrug-resistant tuberculosis – the current global targets for tuberculosis are unlikely to be reached. However, reductions in the incidence of multidrug-resistant tuberculosis should be feasible. We conclude that a shift of patients from tuberculosis dispensaries to designated hospitals is likely to hamper efforts at tuberculosis control if cure rates in the designated hospitals cannot be maintained at a high level. Our results can inform the planning of tuberculosis control in China. PMID:26549907
Sengers, Bram G.; McGinty, Sean; Nouri, Fatma Z.; Argungu, Maryam; Hawkins, Emma; Hadji, Aymen; Weber, Andrew; Taylor, Adam; Sepp, Armin
2016-01-01
ABSTRACT We have developed a mathematical framework for describing a bispecific monoclonal antibody interaction with two independent membrane-bound targets that are expressed on the same cell surface. The bispecific antibody in solution binds either of the two targets first, and then cross-links with the second one while on the cell surface, subject to rate-limiting lateral diffusion step within the lifetime of the monovalently engaged antibody-antigen complex. At experimental densities, only a small fraction of the free targets is expected to lie within the reach of the antibody binding sites at any time. Using ordinary differential equation and Monte Carlo simulation-based models, we validated this approach against an independently published anti-CD4/CD70 DuetMab experimental data set. As a result of dimensional reduction, the cell surface reaction is expected to be so rapid that, in agreement with the experimental data, no monovalently bound bispecific antibody binary complexes accumulate until cross-linking is complete. The dissociation of the bispecific antibody from the ternary cross-linked complex is expected to be significantly slower than that from either of the monovalently bound variants. We estimate that the effective affinity of the bivalently bound bispecific antibody is enhanced for about 4 orders of magnitude over that of the monovalently bound species. This avidity enhancement allows for the highly specific binding of anti-CD4/CD70 DuetMab to the cells that are positive for both target antigens over those that express only one or the other We suggest that the lateral diffusion of target antigens in the cell membrane also plays a key role in the avidity effect of natural antibodies and other bivalent ligands in their interactions with their respective cell surface receptors. PMID:27097222
Sengers, Bram G; McGinty, Sean; Nouri, Fatma Z; Argungu, Maryam; Hawkins, Emma; Hadji, Aymen; Weber, Andrew; Taylor, Adam; Sepp, Armin
2016-07-01
We have developed a mathematical framework for describing a bispecific monoclonal antibody interaction with two independent membrane-bound targets that are expressed on the same cell surface. The bispecific antibody in solution binds either of the two targets first, and then cross-links with the second one while on the cell surface, subject to rate-limiting lateral diffusion step within the lifetime of the monovalently engaged antibody-antigen complex. At experimental densities, only a small fraction of the free targets is expected to lie within the reach of the antibody binding sites at any time. Using ordinary differential equation and Monte Carlo simulation-based models, we validated this approach against an independently published anti-CD4/CD70 DuetMab experimental data set. As a result of dimensional reduction, the cell surface reaction is expected to be so rapid that, in agreement with the experimental data, no monovalently bound bispecific antibody binary complexes accumulate until cross-linking is complete. The dissociation of the bispecific antibody from the ternary cross-linked complex is expected to be significantly slower than that from either of the monovalently bound variants. We estimate that the effective affinity of the bivalently bound bispecific antibody is enhanced for about 4 orders of magnitude over that of the monovalently bound species. This avidity enhancement allows for the highly specific binding of anti-CD4/CD70 DuetMab to the cells that are positive for both target antigens over those that express only one or the other We suggest that the lateral diffusion of target antigens in the cell membrane also plays a key role in the avidity effect of natural antibodies and other bivalent ligands in their interactions with their respective cell surface receptors. PMID:27097222
Hassan, Syed Shah; Tiwari, Sandeep; Guimarães, Luís Carlos; Jamal, Syed Babar; Folador, Edson; Sharma, Neha Barve; de Castro Soares, Siomar; Almeida, Síntia; Ali, Amjad; Islam, Arshad; Póvoa, Fabiana Dias; de Abreu, Vinicius Augusto Carvalho; Jain, Neha; Bhattacharya, Antaripa; Juneja, Lucky; Miyoshi, Anderson; Silva, Artur; Barh, Debmalya; Turjanski, Adrian Gustavo; Azevedo, Vasco; Ferreira, Rafaela Salgado
2014-01-01
Corynebacterium pseudotuberculosis (Cp) is a pathogenic bacterium that causes caseous lymphadenitis (CLA), ulcerative lymphangitis, mastitis, and edematous to a broad spectrum of hosts, including ruminants, thereby threatening economic and dairy industries worldwide. Currently there is no effective drug or vaccine available against Cp. To identify new targets, we adopted a novel integrative strategy, which began with the prediction of the modelome (tridimensional protein structures for the proteome of an organism, generated through comparative modeling) for 15 previously sequenced C. pseudotuberculosis strains. This pan-modelomics approach identified a set of 331 conserved proteins having 95-100% intra-species sequence similarity. Next, we combined subtractive proteomics and modelomics to reveal a set of 10 Cp proteins, which may be essential for the bacteria. Of these, 4 proteins (tcsR, mtrA, nrdI, and ispH) were essential and non-host homologs (considering man, horse, cow and sheep as hosts) and satisfied all criteria of being putative targets. Additionally, we subjected these 4 proteins to virtual screening of a drug-like compound library. In all cases, molecules predicted to form favorable interactions and which showed high complementarity to the target were found among the top ranking compounds. The remaining 6 essential proteins (adk, gapA, glyA, fumC, gnd, and aspA) have homologs in the host proteomes. Their active site cavities were compared to the respective cavities in host proteins. We propose that some of these proteins can be selectively targeted using structure-based drug design approaches (SBDD). Our results facilitate the selection of C. pseudotuberculosis putative proteins for developing broad-spectrum novel drugs and vaccines. A few of the targets identified here have been validated in other microorganisms, suggesting that our modelome strategy is effective and can also be applicable to other pathogens. PMID:25573232
What can transgenic and gene-targeted mouse models teach us about salivary gland physiology?
Melvin, J E; Nguyen, H V; Evans, R L; Shull, G E
2000-12-01
Thousands of genetically modified mice have been developed since the first reports of stable expression of recombinant DNA in this species nearly 20 years ago. This mammalian model system has revolutionized the study of whole-animal, organ, and cell physiology. Transgenic and gene-targeted mice have been widely used to characterize salivary-gland-specific expression and to identify genes associated with tumorigenesis. Moreover, several of these mouse lines have proved to be useful models of salivary gland disease related to impaired immunology, i.e., Sjögren's syndrome, and disease states associated with pathogens. Despite the availability of genetically modified mice, few investigators have taken advantage of this resource to better their understanding of salivary gland function as it relates to the production of saliva. In this article, we describe the methods used to generate transgenic and gene-targeted mice and provide an overview of the advantages of and potential difficulties with these models. Finally, using these mouse models, we discuss the advances made in our understanding of the salivary gland secretion process. PMID:11842924
Modeling human echolocation of near-range targets with an audible sonar.
Kuc, Roman; Kuc, Victor
2016-02-01
Blind humans echolocate nearby targets by emitting palatal clicks and perceiving echoes that the auditory system is not able to resolve temporally. The mechanism for perceiving near-range echoes is not known. This paper models the direct mouth-to-ear signal (MES) and the echo to show that the echo enhances the high-frequency components in the composite MES/echo signal with features that allow echolocation. The mouth emission beam narrows with increasing frequency and exhibits frequency-dependent transmission notches in the backward direction toward the ears as predicted by the piston-in-sphere model. The ears positioned behind the mouth detect a MES that contains predominantly the low frequencies contained in the emission. Hence the high-frequency components in the emission that are perceived by the ears are enhanced by the echoes. A pulse/echo audible sonar verifies this model by echolocating targets from 5 cm range, where the MES and echo overlap significantly, to 55 cm. The model predicts that unambiguous ranging occurs over a limited range and that there is an optimal range that produces the highest range resolution. PMID:26936542
PROPERTIES OF 42 SOLAR-TYPE KEPLER TARGETS FROM THE ASTEROSEISMIC MODELING PORTAL
Metcalfe, T. S.; Mathur, S.; Creevey, O. L.; Doğan, G.; Christensen-Dalsgaard, J.; Karoff, C.; Trampedach, R.; Xu, H.; Bedding, T. R.; Benomar, O.; Chaplin, W. J.; Campante, T. L.; Davies, G. R.; Brown, B. P.; Buzasi, D. L.; Çelik, Z.; Cunha, M. S.; Deheuvels, S.; Derekas, A.; Mauro, M. P. Di; and others
2014-10-01
Recently the number of main-sequence and subgiant stars exhibiting solar-like oscillations that are resolved into individual mode frequencies has increased dramatically. While only a few such data sets were available for detailed modeling just a decade ago, the Kepler mission has produced suitable observations for hundreds of new targets. This rapid expansion in observational capacity has been accompanied by a shift in analysis and modeling strategies to yield uniform sets of derived stellar properties more quickly and easily. We use previously published asteroseismic and spectroscopic data sets to provide a uniform analysis of 42 solar-type Kepler targets from the Asteroseismic Modeling Portal. We find that fitting the individual frequencies typically doubles the precision of the asteroseismic radius, mass, and age compared to grid-based modeling of the global oscillation properties, and improves the precision of the radius and mass by about a factor of three over empirical scaling relations. We demonstrate the utility of the derived properties with several applications.
NASA Astrophysics Data System (ADS)
Patz, Mark David
A non-intrusive buried object classifier for a ground penetrating radar (GPR) system is developed. Various GPR data sets and the implemented processing are described. A model based inversion algorithm that utilizes correlation methodology for target classification is introduced. Experimental data was collected with a continuous wave GPR. Synthetic data was generated with a newly developed software package that implements mathematical models to predict the electromagnetic returns from an underground object. Sample targets and geometries were chosen to produce nine configurations/scenarios for analysis. The real measurement sets for each configuration and the synthetic sets for a family of similar configurations were imaged with the same state-of-the-art signal processing algorithms. The imaged results for the real data measurements were correlated with the imaged results for the synthetic data sets to produce performance measurements, thus producing a procedure that provides a non-invasive assessment of the object and medium determined by the synthetic data set that maximally correlated with the real data return. Synthetic results and experiment results showed good correlations. For the synthetic data, a mathematical model was developed for electromagnetic returns from an object shape (i.e., cylinder, parallelepiped, sphere) composed of a uniform construction (i.e., metal, wood, plastic, clay) within a uniform dielectric material (i.e., air, sand, loam, clay, water). This model was then implemented within a software package, thus providing the ability to generate simulated measurements from any combination of object, construction, and dielectric.